--- a/block/Kconfig.iosched
+++ b/block/Kconfig.iosched
@@ -21,6 +21,16 @@ config IOSCHED_DEADLINE
a new point in the service tree and doing a batch of IO from there
in case of expiry.
+config IOSCHED_ROW
+ tristate "ROW I/O scheduler"
+ ---help---
+ The ROW I/O scheduler gives priority to READ requests over the
+ WRITE requests when dispatching, without starving WRITE requests.
+ Requests are kept in priority queues. Dispatching is done in a RR
+ manner when the dispatch quantum for each queue is calculated
+ according to queue priority.
+ Most suitable for mobile devices.
+
config IOSCHED_CFQ
tristate "CFQ I/O scheduler"
# If BLK_CGROUP is a module, CFQ has to be built as module.
@@ -60,6 +70,12 @@ config IOSCHED_SIO
basic merging, trying to keep a minimum overhead. It is aimed
mainly for aleatory access devices (eg: flash devices).
+config IOSCHED_ZEN
+ tristate "Zen I/O scheduler"
+ default y
+ ---help---
+ FCFS, dispatches are back-inserted, deadlines ensure fairness.
+ Should work best with devices where there is no travel delay.
choice
prompt "Default I/O scheduler"
default DEFAULT_CFQ
@@ -70,6 +86,16 @@ choice
config DEFAULT_DEADLINE
bool "Deadline" if IOSCHED_DEADLINE=y
+ config DEFAULT_ROW
+ bool "ROW" if IOSCHED_ROW=y
+ help
+ The ROW I/O scheduler gives priority to READ requests
+ over the WRITE requests when dispatching, without starving
+ WRITE requests. Requests are kept in priority queues.
+ Dispatching is done in a RR manner when the dispatch quantum
+ for each queue is defined according to queue priority.
+ Most suitable for mobile devices.
+
config DEFAULT_CFQ
bool "CFQ" if IOSCHED_CFQ=y
@@ -81,17 +107,21 @@ choice
config DEFAULT_NOOP
bool "No-op"
-
+
+ config DEFAULT_ZEN
+ bool "ZEN" if IOSCHED_ZEN=y
endchoice
config DEFAULT_IOSCHED
string
default "deadline" if DEFAULT_DEADLINE
+ default "row" if DEFAULT_ROW
default "cfq" if DEFAULT_CFQ
default "sio" if DEFAULT_SIO
default "vr" if DEFAULT_VR
default "noop" if DEFAULT_NOOP
-
+ default "zen" if DEFAULT_ZEN
+
endmenu
endif
--- a/block/Makefile
+++ b/block/Makefile
@@ -12,9 +12,11 @@ obj-$(CONFIG_BLK_CGROUP) += blk-cgroup.o
obj-$(CONFIG_BLK_DEV_THROTTLING) += blk-throttle.o
obj-$(CONFIG_IOSCHED_NOOP) += noop-iosched.o
obj-$(CONFIG_IOSCHED_DEADLINE) += deadline-iosched.o
+obj-$(CONFIG_IOSCHED_ROW) += row-iosched.o
obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o
obj-$(CONFIG_IOSCHED_SIO) += sio-iosched.o
obj-$(CONFIG_IOSCHED_VR) += vr-iosched.o
+obj-$(CONFIG_IOSCHED_ZEN) += zen-iosched.o
obj-$(CONFIG_BLOCK_COMPAT) += compat_ioctl.o
obj-$(CONFIG_BLK_DEV_INTEGRITY) += blk-integrity.o
--- /dev/null
+++ b/block/bfq-cgroup.c
@@ -0,0 +1,836 @@
+/*
+ * BFQ: CGROUPS support.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ file.
+ */
+
+#ifdef CONFIG_CGROUP_BFQIO
+static struct bfqio_cgroup bfqio_root_cgroup = {
+ .weight = BFQ_DEFAULT_GRP_WEIGHT,
+ .ioprio = BFQ_DEFAULT_GRP_IOPRIO,
+ .ioprio_class = BFQ_DEFAULT_GRP_CLASS,
+};
+
+static inline void bfq_init_entity(struct bfq_entity *entity,
+ struct bfq_group *bfqg)
+{
+ entity->weight = entity->new_weight;
+ entity->orig_weight = entity->new_weight;
+ entity->ioprio = entity->new_ioprio;
+ entity->ioprio_class = entity->new_ioprio_class;
+ entity->parent = bfqg->my_entity;
+ entity->sched_data = &bfqg->sched_data;
+}
+
+static struct bfqio_cgroup *cgroup_to_bfqio(struct cgroup *cgroup)
+{
+ return container_of(cgroup_subsys_state(cgroup, bfqio_subsys_id),
+ struct bfqio_cgroup, css);
+}
+
+/*
+ * Search the bfq_group for bfqd into the hash table (by now only a list)
+ * of bgrp. Must be called under rcu_read_lock().
+ */
+static struct bfq_group *bfqio_lookup_group(struct bfqio_cgroup *bgrp,
+ struct bfq_data *bfqd)
+{
+ struct bfq_group *bfqg;
+ struct hlist_node *n;
+ void *key;
+
+ hlist_for_each_entry_rcu(bfqg, n, &bgrp->group_data, group_node) {
+ key = rcu_dereference(bfqg->bfqd);
+ if (key == bfqd)
+ return bfqg;
+ }
+
+ return NULL;
+}
+
+static inline void bfq_group_init_entity(struct bfqio_cgroup *bgrp,
+ struct bfq_group *bfqg)
+{
+ struct bfq_entity *entity = &bfqg->entity;
+
+ entity->weight = entity->new_weight = bgrp->weight;
+ entity->orig_weight = entity->new_weight;
+ entity->ioprio = entity->new_ioprio = bgrp->ioprio;
+ entity->ioprio_class = entity->new_ioprio_class = bgrp->ioprio_class;
+ entity->ioprio_changed = 1;
+ entity->my_sched_data = &bfqg->sched_data;
+}
+
+static inline void bfq_group_set_parent(struct bfq_group *bfqg,
+ struct bfq_group *parent)
+{
+ struct bfq_entity *entity;
+
+ BUG_ON(parent == NULL);
+ BUG_ON(bfqg == NULL);
+
+ entity = &bfqg->entity;
+ entity->parent = parent->my_entity;
+ entity->sched_data = &parent->sched_data;
+}
+
+/**
+ * bfq_group_chain_alloc - allocate a chain of groups.
+ * @bfqd: queue descriptor.
+ * @cgroup: the leaf cgroup this chain starts from.
+ *
+ * Allocate a chain of groups starting from the one belonging to
+ * @cgroup up to the root cgroup. Stop if a cgroup on the chain
+ * to the root has already an allocated group on @bfqd.
+ */
+static struct bfq_group *bfq_group_chain_alloc(struct bfq_data *bfqd,
+ struct cgroup *cgroup)
+{
+ struct bfqio_cgroup *bgrp;
+ struct bfq_group *bfqg, *prev = NULL, *leaf = NULL;
+
+ for (; cgroup != NULL; cgroup = cgroup->parent) {
+ bgrp = cgroup_to_bfqio(cgroup);
+
+ bfqg = bfqio_lookup_group(bgrp, bfqd);
+ if (bfqg != NULL) {
+ /*
+ * All the cgroups in the path from there to the
+ * root must have a bfq_group for bfqd, so we don't
+ * need any more allocations.
+ */
+ break;
+ }
+
+ bfqg = kzalloc(sizeof(*bfqg), GFP_ATOMIC);
+ if (bfqg == NULL)
+ goto cleanup;
+
+ bfq_group_init_entity(bgrp, bfqg);
+ bfqg->my_entity = &bfqg->entity;
+
+ if (leaf == NULL) {
+ leaf = bfqg;
+ prev = leaf;
+ } else {
+ bfq_group_set_parent(prev, bfqg);
+ /*
+ * Build a list of allocated nodes using the bfqd
+ * filed, that is still unused and will be initialized
+ * only after the node will be connected.
+ */
+ prev->bfqd = bfqg;
+ prev = bfqg;
+ }
+ }
+
+ return leaf;
+
+cleanup:
+ while (leaf != NULL) {
+ prev = leaf;
+ leaf = leaf->bfqd;
+ kfree(prev);
+ }
+
+ return NULL;
+}
+
+/**
+ * bfq_group_chain_link - link an allocatd group chain to a cgroup hierarchy.
+ * @bfqd: the queue descriptor.
+ * @cgroup: the leaf cgroup to start from.
+ * @leaf: the leaf group (to be associated to @cgroup).
+ *
+ * Try to link a chain of groups to a cgroup hierarchy, connecting the
+ * nodes bottom-up, so we can be sure that when we find a cgroup in the
+ * hierarchy that already as a group associated to @bfqd all the nodes
+ * in the path to the root cgroup have one too.
+ *
+ * On locking: the queue lock protects the hierarchy (there is a hierarchy
+ * per device) while the bfqio_cgroup lock protects the list of groups
+ * belonging to the same cgroup.
+ */
+static void bfq_group_chain_link(struct bfq_data *bfqd, struct cgroup *cgroup,
+ struct bfq_group *leaf)
+{
+ struct bfqio_cgroup *bgrp;
+ struct bfq_group *bfqg, *next, *prev = NULL;
+ unsigned long flags;
+
+ assert_spin_locked(bfqd->queue->queue_lock);
+
+ for (; cgroup != NULL && leaf != NULL; cgroup = cgroup->parent) {
+ bgrp = cgroup_to_bfqio(cgroup);
+ next = leaf->bfqd;
+
+ bfqg = bfqio_lookup_group(bgrp, bfqd);
+ BUG_ON(bfqg != NULL);
+
+ spin_lock_irqsave(&bgrp->lock, flags);
+
+ rcu_assign_pointer(leaf->bfqd, bfqd);
+ hlist_add_head_rcu(&leaf->group_node, &bgrp->group_data);
+ hlist_add_head(&leaf->bfqd_node, &bfqd->group_list);
+
+ spin_unlock_irqrestore(&bgrp->lock, flags);
+
+ prev = leaf;
+ leaf = next;
+ }
+
+ BUG_ON(cgroup == NULL && leaf != NULL);
+ if (cgroup != NULL && prev != NULL) {
+ bgrp = cgroup_to_bfqio(cgroup);
+ bfqg = bfqio_lookup_group(bgrp, bfqd);
+ bfq_group_set_parent(prev, bfqg);
+ }
+}
+
+/**
+ * bfq_find_alloc_group - return the group associated to @bfqd in @cgroup.
+ * @bfqd: queue descriptor.
+ * @cgroup: cgroup being searched for.
+ *
+ * Return a group associated to @bfqd in @cgroup, allocating one if
+ * necessary. When a group is returned all the cgroups in the path
+ * to the root have a group associated to @bfqd.
+ *
+ * If the allocation fails, return the root group: this breaks guarantees
+ * but is a safe fallbak. If this loss becames a problem it can be
+ * mitigated using the equivalent weight (given by the product of the
+ * weights of the groups in the path from @group to the root) in the
+ * root scheduler.
+ *
+ * We allocate all the missing nodes in the path from the leaf cgroup
+ * to the root and we connect the nodes only after all the allocations
+ * have been successful.
+ */
+static struct bfq_group *bfq_find_alloc_group(struct bfq_data *bfqd,
+ struct cgroup *cgroup)
+{
+ struct bfqio_cgroup *bgrp = cgroup_to_bfqio(cgroup);
+ struct bfq_group *bfqg;
+
+ bfqg = bfqio_lookup_group(bgrp, bfqd);
+ if (bfqg != NULL)
+ return bfqg;
+
+ bfqg = bfq_group_chain_alloc(bfqd, cgroup);
+ if (bfqg != NULL)
+ bfq_group_chain_link(bfqd, cgroup, bfqg);
+ else
+ bfqg = bfqd->root_group;
+
+ return bfqg;
+}
+
+/**
+ * bfq_bfqq_move - migrate @bfqq to @bfqg.
+ * @bfqd: queue descriptor.
+ * @bfqq: the queue to move.
+ * @entity: @bfqq's entity.
+ * @bfqg: the group to move to.
+ *
+ * Move @bfqq to @bfqg, deactivating it from its old group and reactivating
+ * it on the new one. Avoid putting the entity on the old group idle tree.
+ *
+ * Must be called under the queue lock; the cgroup owning @bfqg must
+ * not disappear (by now this just means that we are called under
+ * rcu_read_lock()).
+ */
+static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ struct bfq_entity *entity, struct bfq_group *bfqg)
+{
+ int busy, resume;
+
+ busy = bfq_bfqq_busy(bfqq);
+ resume = !RB_EMPTY_ROOT(&bfqq->sort_list);
+
+ BUG_ON(resume && !entity->on_st);
+ BUG_ON(busy && !resume && entity->on_st && bfqq != bfqd->active_queue);
+
+ if (busy) {
+ BUG_ON(atomic_read(&bfqq->ref) < 2);
+
+ if (!resume)
+ bfq_del_bfqq_busy(bfqd, bfqq, 0);
+ else
+ bfq_deactivate_bfqq(bfqd, bfqq, 0);
+ } else if (entity->on_st)
+ bfq_put_idle_entity(bfq_entity_service_tree(entity), entity);
+
+ /*
+ * Here we use a reference to bfqg. We don't need a refcounter
+ * as the cgroup reference will not be dropped, so that its
+ * destroy() callback will not be invoked.
+ */
+ entity->parent = bfqg->my_entity;
+ entity->sched_data = &bfqg->sched_data;
+
+ if (busy && resume)
+ bfq_activate_bfqq(bfqd, bfqq);
+
+ if (bfqd->active_queue == NULL && !bfqd->rq_in_driver)
+ bfq_schedule_dispatch(bfqd);
+}
+
+/**
+ * __bfq_cic_change_cgroup - move @cic to @cgroup.
+ * @bfqd: the queue descriptor.
+ * @cic: the cic to move.
+ * @cgroup: the cgroup to move to.
+ *
+ * Move cic to cgroup, assuming that bfqd->queue is locked; the caller
+ * has to make sure that the reference to cgroup is valid across the call.
+ *
+ * NOTE: an alternative approach might have been to store the current
+ * cgroup in bfqq and getting a reference to it, reducing the lookup
+ * time here, at the price of slightly more complex code.
+ */
+static struct bfq_group *__bfq_cic_change_cgroup(struct bfq_data *bfqd,
+ struct cfq_io_context *cic,
+ struct cgroup *cgroup)
+{
+ struct bfq_queue *async_bfqq = cic_to_bfqq(cic, 0);
+ struct bfq_queue *sync_bfqq = cic_to_bfqq(cic, 1);
+ struct bfq_entity *entity;
+ struct bfq_group *bfqg;
+
+ bfqg = bfq_find_alloc_group(bfqd, cgroup);
+ if (async_bfqq != NULL) {
+ entity = &async_bfqq->entity;
+
+ if (entity->sched_data != &bfqg->sched_data) {
+ cic_set_bfqq(cic, NULL, 0);
+ bfq_log_bfqq(bfqd, async_bfqq,
+ "cic_change_group: %p %d",
+ async_bfqq, atomic_read(&async_bfqq->ref));
+ bfq_put_queue(async_bfqq);
+ }
+ }
+
+ if (sync_bfqq != NULL) {
+ entity = &sync_bfqq->entity;
+ if (entity->sched_data != &bfqg->sched_data)
+ bfq_bfqq_move(bfqd, sync_bfqq, entity, bfqg);
+ }
+
+ return bfqg;
+}
+
+/**
+ * bfq_cic_change_cgroup - move @cic to @cgroup.
+ * @cic: the cic being migrated.
+ * @cgroup: the destination cgroup.
+ *
+ * When the task owning @cic is moved to @cgroup, @cic is immediately
+ * moved into its new parent group.
+ */
+static void bfq_cic_change_cgroup(struct cfq_io_context *cic,
+ struct cgroup *cgroup)
+{
+ struct bfq_data *bfqd;
+ unsigned long uninitialized_var(flags);
+
+ bfqd = bfq_get_bfqd_locked(&cic->key, &flags);
+ if (bfqd != NULL &&
+ !strncmp(bfqd->queue->elevator->elevator_type->elevator_name,
+ "bfq", ELV_NAME_MAX)) {
+ __bfq_cic_change_cgroup(bfqd, cic, cgroup);
+ bfq_put_bfqd_unlock(bfqd, &flags);
+ }
+}
+
+/**
+ * bfq_cic_update_cgroup - update the cgroup of @cic.
+ * @cic: the @cic to update.
+ *
+ * Make sure that @cic is enqueued in the cgroup of the current task.
+ * We need this in addition to moving cics during the cgroup attach
+ * phase because the task owning @cic could be at its first disk
+ * access or we may end up in the root cgroup as the result of a
+ * memory allocation failure and here we try to move to the right
+ * group.
+ *
+ * Must be called under the queue lock. It is safe to use the returned
+ * value even after the rcu_read_unlock() as the migration/destruction
+ * paths act under the queue lock too. IOW it is impossible to race with
+ * group migration/destruction and end up with an invalid group as:
+ * a) here cgroup has not yet been destroyed, nor its destroy callback
+ * has started execution, as current holds a reference to it,
+ * b) if it is destroyed after rcu_read_unlock() [after current is
+ * migrated to a different cgroup] its attach() callback will have
+ * taken care of remove all the references to the old cgroup data.
+ */
+static struct bfq_group *bfq_cic_update_cgroup(struct cfq_io_context *cic)
+{
+ struct bfq_data *bfqd = cic->key;
+ struct bfq_group *bfqg;
+ struct cgroup *cgroup;
+
+ BUG_ON(bfqd == NULL);
+
+ rcu_read_lock();
+ cgroup = task_cgroup(current, bfqio_subsys_id);
+ bfqg = __bfq_cic_change_cgroup(bfqd, cic, cgroup);
+ rcu_read_unlock();
+
+ return bfqg;
+}
+
+/**
+ * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st.
+ * @st: the service tree being flushed.
+ */
+static inline void bfq_flush_idle_tree(struct bfq_service_tree *st)
+{
+ struct bfq_entity *entity = st->first_idle;
+
+ for (; entity != NULL; entity = st->first_idle)
+ __bfq_deactivate_entity(entity, 0);
+}
+
+/**
+ * bfq_reparent_leaf_entity - move leaf entity to the root_group.
+ * @bfqd: the device data structure with the root group.
+ * @entity: the entity to move.
+ */
+static inline void bfq_reparent_leaf_entity(struct bfq_data *bfqd,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ BUG_ON(bfqq == NULL);
+ bfq_bfqq_move(bfqd, bfqq, entity, bfqd->root_group);
+ return;
+}
+
+/**
+ * bfq_reparent_active_entities - move to the root group all active entities.
+ * @bfqd: the device data structure with the root group.
+ * @bfqg: the group to move from.
+ * @st: the service tree with the entities.
+ *
+ * Needs queue_lock to be taken and reference to be valid over the call.
+ */
+static inline void bfq_reparent_active_entities(struct bfq_data *bfqd,
+ struct bfq_group *bfqg,
+ struct bfq_service_tree *st)
+{
+ struct rb_root *active = &st->active;
+ struct bfq_entity *entity = NULL;
+
+ if (!RB_EMPTY_ROOT(&st->active))
+ entity = bfq_entity_of(rb_first(active));
+
+ for (; entity != NULL ; entity = bfq_entity_of(rb_first(active)))
+ bfq_reparent_leaf_entity(bfqd, entity);
+
+ if (bfqg->sched_data.active_entity != NULL)
+ bfq_reparent_leaf_entity(bfqd, bfqg->sched_data.active_entity);
+
+ return;
+}
+
+/**
+ * bfq_destroy_group - destroy @bfqg.
+ * @bgrp: the bfqio_cgroup containing @bfqg.
+ * @bfqg: the group being destroyed.
+ *
+ * Destroy @bfqg, making sure that it is not referenced from its parent.
+ */
+static void bfq_destroy_group(struct bfqio_cgroup *bgrp, struct bfq_group *bfqg)
+{
+ struct bfq_data *bfqd;
+ struct bfq_service_tree *st;
+ struct bfq_entity *entity = bfqg->my_entity;
+ unsigned long uninitialized_var(flags);
+ int i;
+
+ hlist_del(&bfqg->group_node);
+
+ /*
+ * Empty all service_trees belonging to this group before deactivating
+ * the group itself.
+ */
+ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) {
+ st = bfqg->sched_data.service_tree + i;
+
+ /*
+ * The idle tree may still contain bfq_queues belonging
+ * to exited task because they never migrated to a different
+ * cgroup from the one being destroyed now. Noone else
+ * can access them so it's safe to act without any lock.
+ */
+ bfq_flush_idle_tree(st);
+
+ /*
+ * It may happen that some queues are still active
+ * (busy) upon group destruction (if the corresponding
+ * processes have been forced to terminate). We move
+ * all the leaf entities corresponding to these queues
+ * to the root_group.
+ * Also, it may happen that the group has an entity
+ * under service, which is disconnected from the active
+ * tree: it must be moved, too.
+ * There is no need to put the sync queues, as the
+ * scheduler has taken no reference.
+ */
+ bfqd = bfq_get_bfqd_locked(&bfqg->bfqd, &flags);
+ if (bfqd != NULL) {
+ bfq_reparent_active_entities(bfqd, bfqg, st);
+ bfq_put_bfqd_unlock(bfqd, &flags);
+ }
+ BUG_ON(!RB_EMPTY_ROOT(&st->active));
+ BUG_ON(!RB_EMPTY_ROOT(&st->idle));
+ }
+ BUG_ON(bfqg->sched_data.next_active != NULL);
+ BUG_ON(bfqg->sched_data.active_entity != NULL);
+
+ /*
+ * We may race with device destruction, take extra care when
+ * dereferencing bfqg->bfqd.
+ */
+ bfqd = bfq_get_bfqd_locked(&bfqg->bfqd, &flags);
+ if (bfqd != NULL) {
+ hlist_del(&bfqg->bfqd_node);
+ __bfq_deactivate_entity(entity, 0);
+ bfq_put_async_queues(bfqd, bfqg);
+ bfq_put_bfqd_unlock(bfqd, &flags);
+ }
+ BUG_ON(entity->tree != NULL);
+
+ /*
+ * No need to defer the kfree() to the end of the RCU grace
+ * period: we are called from the destroy() callback of our
+ * cgroup, so we can be sure that noone is a) still using
+ * this cgroup or b) doing lookups in it.
+ */
+ kfree(bfqg);
+}
+
+/**
+ * bfq_disconnect_groups - diconnect @bfqd from all its groups.
+ * @bfqd: the device descriptor being exited.
+ *
+ * When the device exits we just make sure that no lookup can return
+ * the now unused group structures. They will be deallocated on cgroup
+ * destruction.
+ */
+static void bfq_disconnect_groups(struct bfq_data *bfqd)
+{
+ struct hlist_node *pos, *n;
+ struct bfq_group *bfqg;
+
+ bfq_log(bfqd, "disconnect_groups beginning") ;
+ hlist_for_each_entry_safe(bfqg, pos, n, &bfqd->group_list, bfqd_node) {
+ hlist_del(&bfqg->bfqd_node);
+
+ __bfq_deactivate_entity(bfqg->my_entity, 0);
+
+ /*
+ * Don't remove from the group hash, just set an
+ * invalid key. No lookups can race with the
+ * assignment as bfqd is being destroyed; this
+ * implies also that new elements cannot be added
+ * to the list.
+ */
+ rcu_assign_pointer(bfqg->bfqd, NULL);
+
+ bfq_log(bfqd, "disconnect_groups: put async for group %p",
+ bfqg) ;
+ bfq_put_async_queues(bfqd, bfqg);
+ }
+}
+
+static inline void bfq_free_root_group(struct bfq_data *bfqd)
+{
+ struct bfqio_cgroup *bgrp = &bfqio_root_cgroup;
+ struct bfq_group *bfqg = bfqd->root_group;
+
+ bfq_put_async_queues(bfqd, bfqg);
+
+ spin_lock_irq(&bgrp->lock);
+ hlist_del_rcu(&bfqg->group_node);
+ spin_unlock_irq(&bgrp->lock);
+
+ /*
+ * No need to synchronize_rcu() here: since the device is gone
+ * there cannot be any read-side access to its root_group.
+ */
+ kfree(bfqg);
+}
+
+static struct bfq_group *bfq_alloc_root_group(struct bfq_data *bfqd, int node)
+{
+ struct bfq_group *bfqg;
+ struct bfqio_cgroup *bgrp;
+ int i;
+
+ bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node);
+ if (bfqg == NULL)
+ return NULL;
+
+ bfqg->entity.parent = NULL;
+ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
+ bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
+
+ bgrp = &bfqio_root_cgroup;
+ spin_lock_irq(&bgrp->lock);
+ rcu_assign_pointer(bfqg->bfqd, bfqd);
+ hlist_add_head_rcu(&bfqg->group_node, &bgrp->group_data);
+ spin_unlock_irq(&bgrp->lock);
+
+ return bfqg;
+}
+
+#define SHOW_FUNCTION(__VAR) \
+static u64 bfqio_cgroup_##__VAR##_read(struct cgroup *cgroup, \
+ struct cftype *cftype) \
+{ \
+ struct bfqio_cgroup *bgrp; \
+ u64 ret; \
+ \
+ if (!cgroup_lock_live_group(cgroup)) \
+ return -ENODEV; \
+ \
+ bgrp = cgroup_to_bfqio(cgroup); \
+ spin_lock_irq(&bgrp->lock); \
+ ret = bgrp->__VAR; \
+ spin_unlock_irq(&bgrp->lock); \
+ \
+ cgroup_unlock(); \
+ \
+ return ret; \
+}
+
+SHOW_FUNCTION(weight);
+SHOW_FUNCTION(ioprio);
+SHOW_FUNCTION(ioprio_class);
+#undef SHOW_FUNCTION
+
+#define STORE_FUNCTION(__VAR, __MIN, __MAX) \
+static int bfqio_cgroup_##__VAR##_write(struct cgroup *cgroup, \
+ struct cftype *cftype, \
+ u64 val) \
+{ \
+ struct bfqio_cgroup *bgrp; \
+ struct bfq_group *bfqg; \
+ struct hlist_node *n; \
+ \
+ if (val < (__MIN) || val > (__MAX)) \
+ return -EINVAL; \
+ \
+ if (!cgroup_lock_live_group(cgroup)) \
+ return -ENODEV; \
+ \
+ bgrp = cgroup_to_bfqio(cgroup); \
+ \
+ spin_lock_irq(&bgrp->lock); \
+ bgrp->__VAR = (unsigned short)val; \
+ hlist_for_each_entry(bfqg, n, &bgrp->group_data, group_node) { \
+ bfqg->entity.new_##__VAR = (unsigned short)val; \
+ smp_wmb(); \
+ bfqg->entity.ioprio_changed = 1; \
+ } \
+ spin_unlock_irq(&bgrp->lock); \
+ \
+ cgroup_unlock(); \
+ \
+ return 0; \
+}
+
+STORE_FUNCTION(weight, BFQ_MIN_WEIGHT, BFQ_MAX_WEIGHT);
+STORE_FUNCTION(ioprio, 0, IOPRIO_BE_NR - 1);
+STORE_FUNCTION(ioprio_class, IOPRIO_CLASS_RT, IOPRIO_CLASS_IDLE);
+#undef STORE_FUNCTION
+
+static struct cftype bfqio_files[] = {
+ {
+ .name = "weight",
+ .read_u64 = bfqio_cgroup_weight_read,
+ .write_u64 = bfqio_cgroup_weight_write,
+ },
+ {
+ .name = "ioprio",
+ .read_u64 = bfqio_cgroup_ioprio_read,
+ .write_u64 = bfqio_cgroup_ioprio_write,
+ },
+ {
+ .name = "ioprio_class",
+ .read_u64 = bfqio_cgroup_ioprio_class_read,
+ .write_u64 = bfqio_cgroup_ioprio_class_write,
+ },
+};
+
+static int bfqio_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
+{
+ return cgroup_add_files(cgroup, subsys, bfqio_files,
+ ARRAY_SIZE(bfqio_files));
+}
+
+static struct cgroup_subsys_state *bfqio_create(struct cgroup_subsys *subsys,
+ struct cgroup *cgroup)
+{
+ struct bfqio_cgroup *bgrp;
+
+ if (cgroup->parent != NULL) {
+ bgrp = kzalloc(sizeof(*bgrp), GFP_KERNEL);
+ if (bgrp == NULL)
+ return ERR_PTR(-ENOMEM);
+ } else
+ bgrp = &bfqio_root_cgroup;
+
+ spin_lock_init(&bgrp->lock);
+ INIT_HLIST_HEAD(&bgrp->group_data);
+ bgrp->ioprio = BFQ_DEFAULT_GRP_IOPRIO;
+ bgrp->ioprio_class = BFQ_DEFAULT_GRP_CLASS;
+
+ return &bgrp->css;
+}
+
+/*
+ * We cannot support shared io contexts, as we have no mean to support
+ * two tasks with the same ioc in two different groups without major rework
+ * of the main cic/bfqq data structures. By now we allow a task to change
+ * its cgroup only if it's the only owner of its ioc; the drawback of this
+ * behavior is that a group containing a task that forked using CLONE_IO
+ * will not be destroyed until the tasks sharing the ioc die.
+ */
+static int bfqio_can_attach(struct cgroup_subsys *subsys, struct cgroup *cgroup,
+ struct task_struct *tsk)
+{
+ struct io_context *ioc;
+ int ret = 0;
+
+ /* task_lock() is needed to avoid races with exit_io_context() */
+ task_lock(tsk);
+ ioc = tsk->io_context;
+ if (ioc != NULL && atomic_read(&ioc->nr_tasks) > 1)
+ /*
+ * ioc == NULL means that the task is either too young or
+ * exiting: if it has still no ioc the ioc can't be shared,
+ * if the task is exiting the attach will fail anyway, no
+ * matter what we return here.
+ */
+ ret = -EINVAL;
+ task_unlock(tsk);
+
+ return ret;
+}
+
+static void bfqio_attach(struct cgroup_subsys *subsys, struct cgroup *cgroup,
+ struct cgroup *prev, struct task_struct *tsk)
+{
+ struct io_context *ioc;
+ struct cfq_io_context *cic;
+ struct hlist_node *n;
+
+ task_lock(tsk);
+ ioc = tsk->io_context;
+ if (ioc != NULL) {
+ BUG_ON(atomic_long_read(&ioc->refcount) == 0);
+ atomic_long_inc(&ioc->refcount);
+ }
+ task_unlock(tsk);
+
+ if (ioc == NULL)
+ return;
+
+ rcu_read_lock();
+ hlist_for_each_entry_rcu(cic, n, &ioc->bfq_cic_list, cic_list)
+ bfq_cic_change_cgroup(cic, cgroup);
+ rcu_read_unlock();
+
+ put_io_context(ioc);
+}
+
+static void bfqio_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
+{
+ struct bfqio_cgroup *bgrp = cgroup_to_bfqio(cgroup);
+ struct hlist_node *n, *tmp;
+ struct bfq_group *bfqg;
+
+ /*
+ * Since we are destroying the cgroup, there are no more tasks
+ * referencing it, and all the RCU grace periods that may have
+ * referenced it are ended (as the destruction of the parent
+ * cgroup is RCU-safe); bgrp->group_data will not be accessed by
+ * anything else and we don't need any synchronization.
+ */
+ hlist_for_each_entry_safe(bfqg, n, tmp, &bgrp->group_data, group_node)
+ bfq_destroy_group(bgrp, bfqg);
+
+ BUG_ON(!hlist_empty(&bgrp->group_data));
+
+ kfree(bgrp);
+}
+
+struct cgroup_subsys bfqio_subsys = {
+ .name = "bfqio",
+ .create = bfqio_create,
+ .can_attach = bfqio_can_attach,
+ .attach = bfqio_attach,
+ .destroy = bfqio_destroy,
+ .populate = bfqio_populate,
+ .subsys_id = bfqio_subsys_id,
+};
+#else
+static inline void bfq_init_entity(struct bfq_entity *entity,
+ struct bfq_group *bfqg)
+{
+ entity->weight = entity->new_weight;
+ entity->orig_weight = entity->new_weight;
+ entity->ioprio = entity->new_ioprio;
+ entity->ioprio_class = entity->new_ioprio_class;
+ entity->sched_data = &bfqg->sched_data;
+}
+
+static inline struct bfq_group *
+bfq_cic_update_cgroup(struct cfq_io_context *cic)
+{
+ struct bfq_data *bfqd = cic->key;
+ return bfqd->root_group;
+}
+
+static inline void bfq_bfqq_move(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ struct bfq_entity *entity,
+ struct bfq_group *bfqg)
+{
+}
+
+static inline void bfq_disconnect_groups(struct bfq_data *bfqd)
+{
+ bfq_put_async_queues(bfqd, bfqd->root_group);
+}
+
+static inline void bfq_free_root_group(struct bfq_data *bfqd)
+{
+ kfree(bfqd->root_group);
+}
+
+static struct bfq_group *bfq_alloc_root_group(struct bfq_data *bfqd, int node)
+{
+ struct bfq_group *bfqg;
+ int i;
+
+ bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node);
+ if (bfqg == NULL)
+ return NULL;
+
+ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
+ bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
+
+ return bfqg;
+}
+#endif
--- /dev/null
+++ b/block/bfq-ioc.c
@@ -0,0 +1,382 @@
+/*
+ * BFQ: I/O context handling.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
+ */
+
+/**
+ * bfq_cic_free_rcu - deferred cic freeing.
+ * @head: RCU head of the cic to free.
+ *
+ * Free the cic containing @head and, if it was the last one and
+ * the module is exiting wake up anyone waiting for its deallocation
+ * (see bfq_exit()).
+ */
+static void bfq_cic_free_rcu(struct rcu_head *head)
+{
+ struct cfq_io_context *cic;
+
+ cic = container_of(head, struct cfq_io_context, rcu_head);
+
+ kmem_cache_free(bfq_ioc_pool, cic);
+ elv_ioc_count_dec(bfq_ioc_count);
+
+ if (bfq_ioc_gone != NULL) {
+ spin_lock(&bfq_ioc_gone_lock);
+ if (bfq_ioc_gone != NULL &&
+ !elv_ioc_count_read(bfq_ioc_count)) {
+ complete(bfq_ioc_gone);
+ bfq_ioc_gone = NULL;
+ }
+ spin_unlock(&bfq_ioc_gone_lock);
+ }
+}
+
+static void bfq_cic_free(struct cfq_io_context *cic)
+{
+ call_rcu(&cic->rcu_head, bfq_cic_free_rcu);
+}
+
+/**
+ * cic_free_func - disconnect a cic ready to be freed.
+ * @ioc: the io_context @cic belongs to.
+ * @cic: the cic to be freed.
+ *
+ * Remove @cic from the @ioc radix tree hash and from its cic list,
+ * deferring the deallocation of @cic to the end of the current RCU
+ * grace period. This assumes that __bfq_exit_single_io_context()
+ * has already been called for @cic.
+ */
+static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
+{
+ unsigned long flags;
+ unsigned long dead_key = (unsigned long) cic->key;
+
+ BUG_ON(!(dead_key & CIC_DEAD_KEY));
+
+ spin_lock_irqsave(&ioc->lock, flags);
+ radix_tree_delete(&ioc->bfq_radix_root,
+ dead_key >> CIC_DEAD_INDEX_SHIFT);
+ hlist_del_init_rcu(&cic->cic_list);
+ spin_unlock_irqrestore(&ioc->lock, flags);
+
+ bfq_cic_free(cic);
+}
+
+static void bfq_free_io_context(struct io_context *ioc)
+{
+ /*
+ * ioc->refcount is zero here, or we are called from elv_unregister(),
+ * so no more cic's are allowed to be linked into this ioc. So it
+ * should be ok to iterate over the known list, we will see all cic's
+ * since no new ones are added.
+ */
+ call_for_each_cic(ioc, cic_free_func);
+}
+
+/**
+ * __bfq_exit_single_io_context - deassociate @cic from any running task.
+ * @bfqd: bfq_data on which @cic is valid.
+ * @cic: the cic being exited.
+ *
+ * Whenever no more tasks are using @cic or @bfqd is deallocated we
+ * need to invalidate its entry in the radix tree hash table and to
+ * release the queues it refers to.
+ *
+ * Called under the queue lock.
+ */
+static void __bfq_exit_single_io_context(struct bfq_data *bfqd,
+ struct cfq_io_context *cic)
+{
+ struct io_context *ioc = cic->ioc;
+
+ list_del_init(&cic->queue_list);
+
+ /*
+ * Make sure dead mark is seen for dead queues
+ */
+ smp_wmb();
+ rcu_assign_pointer(cic->key, bfqd_dead_key(bfqd));
+
+ /*
+ * No write-side locking as no task is using @ioc (they're exited
+ * or bfqd is being deallocated.
+ */
+ rcu_read_lock();
+ if (rcu_dereference(ioc->ioc_data) == cic) {
+ rcu_read_unlock();
+ spin_lock(&ioc->lock);
+ rcu_assign_pointer(ioc->ioc_data, NULL);
+ spin_unlock(&ioc->lock);
+ } else
+ rcu_read_unlock();
+
+ if (cic->cfqq[BLK_RW_ASYNC] != NULL) {
+ bfq_exit_bfqq(bfqd, cic->cfqq[BLK_RW_ASYNC]);
+ cic->cfqq[BLK_RW_ASYNC] = NULL;
+ }
+
+ if (cic->cfqq[BLK_RW_SYNC] != NULL) {
+ bfq_exit_bfqq(bfqd, cic->cfqq[BLK_RW_SYNC]);
+ cic->cfqq[BLK_RW_SYNC] = NULL;
+ }
+}
+
+/**
+ * bfq_exit_single_io_context - deassociate @cic from @ioc (unlocked version).
+ * @ioc: the io_context @cic belongs to.
+ * @cic: the cic being exited.
+ *
+ * Take the queue lock and call __bfq_exit_single_io_context() to do the
+ * rest of the work. We take care of possible races with bfq_exit_queue()
+ * using bfq_get_bfqd_locked() (and abusing a little bit the RCU mechanism).
+ */
+static void bfq_exit_single_io_context(struct io_context *ioc,
+ struct cfq_io_context *cic)
+{
+ struct bfq_data *bfqd;
+ unsigned long uninitialized_var(flags);
+
+ bfqd = bfq_get_bfqd_locked(&cic->key, &flags);
+ if (bfqd != NULL) {
+ __bfq_exit_single_io_context(bfqd, cic);
+ bfq_put_bfqd_unlock(bfqd, &flags);
+ }
+}
+
+/**
+ * bfq_exit_io_context - deassociate @ioc from all cics it owns.
+ * @ioc: the @ioc being exited.
+ *
+ * No more processes are using @ioc we need to clean up and put the
+ * internal structures we have that belongs to that process. Loop
+ * through all its cics, locking their queues and exiting them.
+ */
+static void bfq_exit_io_context(struct io_context *ioc)
+{
+ call_for_each_cic(ioc, bfq_exit_single_io_context);
+}
+
+static struct cfq_io_context *bfq_alloc_io_context(struct bfq_data *bfqd,
+ gfp_t gfp_mask)
+{
+ struct cfq_io_context *cic;
+
+ cic = kmem_cache_alloc_node(bfq_ioc_pool, gfp_mask | __GFP_ZERO,
+ bfqd->queue->node);
+ if (cic != NULL) {
+ cic->last_end_request = jiffies;
+ INIT_LIST_HEAD(&cic->queue_list);
+ INIT_HLIST_NODE(&cic->cic_list);
+ cic->dtor = bfq_free_io_context;
+ cic->exit = bfq_exit_io_context;
+ elv_ioc_count_inc(bfq_ioc_count);
+ }
+
+ return cic;
+}
+
+/**
+ * bfq_drop_dead_cic - free an exited cic.
+ * @bfqd: bfq data for the device in use.
+ * @ioc: io_context owning @cic.
+ * @cic: the @cic to free.
+ *
+ * We drop cfq io contexts lazily, so we may find a dead one.
+ */
+static void bfq_drop_dead_cic(struct bfq_data *bfqd, struct io_context *ioc,
+ struct cfq_io_context *cic)
+{
+ unsigned long flags;
+
+ WARN_ON(!list_empty(&cic->queue_list));
+ BUG_ON(cic->key != bfqd_dead_key(bfqd));
+
+ spin_lock_irqsave(&ioc->lock, flags);
+
+ BUG_ON(ioc->ioc_data == cic);
+
+ /*
+ * With shared I/O contexts two lookups may race and drop the
+ * same cic more than one time: RCU guarantees that the storage
+ * will not be freed too early, here we make sure that we do
+ * not try to remove the cic from the hashing structures multiple
+ * times.
+ */
+ if (!hlist_unhashed(&cic->cic_list)) {
+ radix_tree_delete(&ioc->bfq_radix_root, bfqd->cic_index);
+ hlist_del_init_rcu(&cic->cic_list);
+ bfq_cic_free(cic);
+ }
+
+ spin_unlock_irqrestore(&ioc->lock, flags);
+}
+
+/**
+ * bfq_cic_lookup - search into @ioc a cic associated to @bfqd.
+ * @bfqd: the lookup key.
+ * @ioc: the io_context of the process doing I/O.
+ *
+ * If @ioc already has a cic associated to @bfqd return it, return %NULL
+ * otherwise.
+ */
+static struct cfq_io_context *bfq_cic_lookup(struct bfq_data *bfqd,
+ struct io_context *ioc)
+{
+ struct cfq_io_context *cic;
+ unsigned long flags;
+ void *k;
+
+ if (unlikely(ioc == NULL))
+ return NULL;
+
+ rcu_read_lock();
+
+ /* We maintain a last-hit cache, to avoid browsing over the tree. */
+ cic = rcu_dereference(ioc->ioc_data);
+ if (cic != NULL) {
+ k = rcu_dereference(cic->key);
+ if (k == bfqd)
+ goto out;
+ }
+
+ do {
+ cic = radix_tree_lookup(&ioc->bfq_radix_root,
+ bfqd->cic_index);
+ if (cic == NULL)
+ goto out;
+
+ k = rcu_dereference(cic->key);
+ if (unlikely(k != bfqd)) {
+ rcu_read_unlock();
+ bfq_drop_dead_cic(bfqd, ioc, cic);
+ rcu_read_lock();
+ continue;
+ }
+
+ spin_lock_irqsave(&ioc->lock, flags);
+ rcu_assign_pointer(ioc->ioc_data, cic);
+ spin_unlock_irqrestore(&ioc->lock, flags);
+ break;
+ } while (1);
+
+out:
+ rcu_read_unlock();
+
+ return cic;
+}
+
+/**
+ * bfq_cic_link - add @cic to @ioc.
+ * @bfqd: bfq_data @cic refers to.
+ * @ioc: io_context @cic belongs to.
+ * @cic: the cic to link.
+ * @gfp_mask: the mask to use for radix tree preallocations.
+ *
+ * Add @cic to @ioc, using @bfqd as the search key. This enables us to
+ * lookup the process specific cfq io context when entered from the block
+ * layer. Also adds @cic to a per-bfqd list, used when this queue is
+ * removed.
+ */
+static int bfq_cic_link(struct bfq_data *bfqd, struct io_context *ioc,
+ struct cfq_io_context *cic, gfp_t gfp_mask)
+{
+ unsigned long flags;
+ int ret;
+
+ ret = radix_tree_preload(gfp_mask);
+ if (ret == 0) {
+ cic->ioc = ioc;
+
+ /* No write-side locking, cic is not published yet. */
+ rcu_assign_pointer(cic->key, bfqd);
+
+ spin_lock_irqsave(&ioc->lock, flags);
+ ret = radix_tree_insert(&ioc->bfq_radix_root,
+ bfqd->cic_index, cic);
+ if (ret == 0)
+ hlist_add_head_rcu(&cic->cic_list, &ioc->bfq_cic_list);
+ spin_unlock_irqrestore(&ioc->lock, flags);
+
+ radix_tree_preload_end();
+
+ if (ret == 0) {
+ spin_lock_irqsave(bfqd->queue->queue_lock, flags);
+ list_add(&cic->queue_list, &bfqd->cic_list);
+ spin_unlock_irqrestore(bfqd->queue->queue_lock, flags);
+ }
+ }
+
+ if (ret != 0)
+ printk(KERN_ERR "bfq: cic link failed!\n");
+
+ return ret;
+}
+
+/**
+ * bfq_ioc_set_ioprio - signal a priority change to the cics belonging to @ioc.
+ * @ioc: the io_context changing its priority.
+ */
+static inline void bfq_ioc_set_ioprio(struct io_context *ioc)
+{
+ call_for_each_cic(ioc, bfq_changed_ioprio);
+}
+
+/**
+ * bfq_get_io_context - return the @cic associated to @bfqd in @ioc.
+ * @bfqd: the search key.
+ * @gfp_mask: the mask to use for cic allocation.
+ *
+ * Setup general io context and cfq io context. There can be several cfq
+ * io contexts per general io context, if this process is doing io to more
+ * than one device managed by cfq.
+ */
+static struct cfq_io_context *bfq_get_io_context(struct bfq_data *bfqd,
+ gfp_t gfp_mask)
+{
+ struct io_context *ioc = NULL;
+ struct cfq_io_context *cic;
+
+ might_sleep_if(gfp_mask & __GFP_WAIT);
+
+ ioc = get_io_context(gfp_mask, bfqd->queue->node);
+ if (ioc == NULL)
+ return NULL;
+
+ /* Lookup for an existing cic. */
+ cic = bfq_cic_lookup(bfqd, ioc);
+ if (cic != NULL)
+ goto out;
+
+ /* Alloc one if needed. */
+ cic = bfq_alloc_io_context(bfqd, gfp_mask);
+ if (cic == NULL)
+ goto err;
+
+ /* Link it into the ioc's radix tree and cic list. */
+ if (bfq_cic_link(bfqd, ioc, cic, gfp_mask) != 0)
+ goto err_free;
+
+out:
+ /*
+ * test_and_clear_bit() implies a memory barrier, paired with
+ * the wmb() in fs/ioprio.c, so the value seen for ioprio is the
+ * new one.
+ */
+ if (unlikely(test_and_clear_bit(IOC_BFQ_IOPRIO_CHANGED,
+ ioc->ioprio_changed)))
+ bfq_ioc_set_ioprio(ioc);
+
+ return cic;
+err_free:
+ bfq_cic_free(cic);
+err:
+ put_io_context(ioc);
+ return NULL;
+}
--- /dev/null
+++ b/block/bfq-iosched.c
@@ -0,0 +1,3061 @@
+/*
+ * BFQ, or Budget Fair Queueing, disk scheduler.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ file.
+ *
+ * BFQ is a proportional share disk scheduling algorithm based on the
+ * slice-by-slice service scheme of CFQ. But BFQ assigns budgets,
+ * measured in number of sectors, to tasks instead of time slices.
+ * The disk is not granted to the active task for a given time slice,
+ * but until it has exahusted its assigned budget. This change from
+ * the time to the service domain allows BFQ to distribute the disk
+ * bandwidth among tasks as desired, without any distortion due to
+ * ZBR, workload fluctuations or other factors. BFQ uses an ad hoc
+ * internal scheduler, called B-WF2Q+, to schedule tasks according to
+ * their budgets. Thanks to this accurate scheduler, BFQ can afford
+ * to assign high budgets to disk-bound non-seeky tasks (to boost the
+ * throughput), and yet guarantee low latencies to interactive and
+ * soft real-time applications.
+ *
+ * BFQ has been introduced in [1], where the interested reader can
+ * find an accurate description of the algorithm, the bandwidth
+ * distribution and latency guarantees it provides, plus formal proofs
+ * of all the properties. With respect to the algorithm presented in
+ * the paper, this implementation adds several little heuristics, and
+ * a hierarchical extension, based on H-WF2Q+.
+ *
+ * B-WF2Q+ is based on WF2Q+, that is described in [2], together with
+ * H-WF2Q+, while the augmented tree used to implement B-WF2Q+ with O(log N)
+ * complexity derives from the one introduced with EEVDF in [3].
+ *
+ * [1] P. Valente and F. Checconi, ``High Throughput Disk Scheduling
+ * with Deterministic Guarantees on Bandwidth Distribution,'',
+ * IEEE Transactions on Computer, May 2010.
+ *
+ * http://algo.ing.unimo.it/people/paolo/disk_sched/bfq-techreport.pdf
+ *
+ * [2] Jon C.R. Bennett and H. Zhang, ``Hierarchical Packet Fair Queueing
+ * Algorithms,'' IEEE/ACM Transactions on Networking, 5(5):675-689,
+ * Oct 1997.
+ *
+ * http://www.cs.cmu.edu/~hzhang/papers/TON-97-Oct.ps.gz
+ *
+ * [3] I. Stoica and H. Abdel-Wahab, ``Earliest Eligible Virtual Deadline
+ * First: A Flexible and Accurate Mechanism for Proportional Share
+ * Resource Allocation,'' technical report.
+ *
+ * http://www.cs.berkeley.edu/~istoica/papers/eevdf-tr-95.pdf
+ */
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+#include <linux/cgroup.h>
+#include <linux/elevator.h>
+#include <linux/jiffies.h>
+#include <linux/rbtree.h>
+#include <linux/ioprio.h>
+#include "bfq.h"
+
+/* Max number of dispatches in one round of service. */
+static const int bfq_quantum = 4;
+
+/* Expiration time of sync (0) and async (1) requests, in jiffies. */
+static const int bfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
+
+/* Maximum backwards seek, in KiB. */
+static const int bfq_back_max = 16 * 1024;
+
+/* Penalty of a backwards seek, in number of sectors. */
+static const int bfq_back_penalty = 2;
+
+/* Idling period duration, in jiffies. */
+static int bfq_slice_idle = HZ / 125;
+
+/* Default maximum budget values, in sectors and number of requests. */
+static const int bfq_default_max_budget = 16 * 1024;
+static const int bfq_max_budget_async_rq = 4;
+
+/*
+ * Async to sync throughput distribution is controlled as follows:
+ * when an async request is served, the entity is charged the number
+ * of sectors of the request, multipled by the factor below
+ */
+static const int bfq_async_charge_factor = 10;
+
+/* Default timeout values, in jiffies, approximating CFQ defaults. */
+static const int bfq_timeout_sync = HZ / 8;
+static int bfq_timeout_async = HZ / 25;
+
+struct kmem_cache *bfq_pool;
+struct kmem_cache *bfq_ioc_pool;
+
+static DEFINE_PER_CPU(unsigned long, bfq_ioc_count);
+static struct completion *bfq_ioc_gone;
+static DEFINE_SPINLOCK(bfq_ioc_gone_lock);
+
+static DEFINE_SPINLOCK(cic_index_lock);
+static DEFINE_IDA(cic_index_ida);
+
+/* Below this threshold (in ms), we consider thinktime immediate. */
+#define BFQ_MIN_TT 2
+
+/* hw_tag detection: parallel requests threshold and min samples needed. */
+#define BFQ_HW_QUEUE_THRESHOLD 4
+#define BFQ_HW_QUEUE_SAMPLES 32
+
+#define BFQQ_SEEK_THR (sector_t)(8 * 1024)
+#define BFQQ_SEEKY(bfqq) ((bfqq)->seek_mean > BFQQ_SEEK_THR)
+
+/* Min samples used for peak rate estimation (for autotuning). */
+#define BFQ_PEAK_RATE_SAMPLES 32
+
+/* Shift used for peak rate fixed precision calculations. */
+#define BFQ_RATE_SHIFT 16
+
+/*
+ * The duration of the weight raising for interactive applications is
+ * computed automatically (as default behaviour), using the following
+ * formula: duration = (R / r) * T, where r is the peak rate of the
+ * disk, and R and T are two reference parameters. In particular, R is
+ * the peak rate of a reference disk, and T is about the maximum time
+ * for starting popular large applications on that disk, under BFQ and
+ * while reading two files in parallel. Finally, BFQ uses two
+ * different pairs (R, T) depending on whether the disk is rotational
+ * or non-rotational.
+ */
+#define T_rot (msecs_to_jiffies(5500))
+#define T_nonrot (msecs_to_jiffies(2000))
+/* Next two quantities are in sectors/usec, left-shifted by BFQ_RATE_SHIFT */
+#define R_rot 17415
+#define R_nonrot 34791
+
+#define BFQ_SERVICE_TREE_INIT ((struct bfq_service_tree) \
+ { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
+
+#define RQ_CIC(rq) \
+ ((struct cfq_io_context *) (rq)->elevator_private[0])
+#define RQ_BFQQ(rq) ((rq)->elevator_private[1])
+
+static inline void bfq_schedule_dispatch(struct bfq_data *bfqd);
+
+#include "bfq-ioc.c"
+#include "bfq-sched.c"
+#include "bfq-cgroup.c"
+
+#define bfq_class_idle(bfqq) ((bfqq)->entity.ioprio_class ==\
+ IOPRIO_CLASS_IDLE)
+#define bfq_class_rt(bfqq) ((bfqq)->entity.ioprio_class ==\
+ IOPRIO_CLASS_RT)
+
+#define bfq_sample_valid(samples) ((samples) > 80)
+
+/*
+ * We regard a request as SYNC, if either it's a read or has the SYNC bit
+ * set (in which case it could also be a direct WRITE).
+ */
+static inline int bfq_bio_sync(struct bio *bio)
+{
+ if (bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC))
+ return 1;
+
+ return 0;
+}
+
+/*
+ * Scheduler run of queue, if there are requests pending and no one in the
+ * driver that will restart queueing.
+ */
+static inline void bfq_schedule_dispatch(struct bfq_data *bfqd)
+{
+ if (bfqd->queued != 0) {
+ bfq_log(bfqd, "schedule dispatch");
+ kblockd_schedule_work(bfqd->queue, &bfqd->unplug_work);
+ }
+}
+
+/*
+ * Lifted from AS - choose which of rq1 and rq2 that is best served now.
+ * We choose the request that is closesr to the head right now. Distance
+ * behind the head is penalized and only allowed to a certain extent.
+ */
+static struct request *bfq_choose_req(struct bfq_data *bfqd,
+ struct request *rq1,
+ struct request *rq2,
+ sector_t last)
+{
+ sector_t s1, s2, d1 = 0, d2 = 0;
+ unsigned long back_max;
+#define BFQ_RQ1_WRAP 0x01 /* request 1 wraps */
+#define BFQ_RQ2_WRAP 0x02 /* request 2 wraps */
+ unsigned wrap = 0; /* bit mask: requests behind the disk head? */
+
+ if (rq1 == NULL || rq1 == rq2)
+ return rq2;
+ if (rq2 == NULL)
+ return rq1;
+
+ if (rq_is_sync(rq1) && !rq_is_sync(rq2))
+ return rq1;
+ else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
+ return rq2;
+ if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
+ return rq1;
+ else if ((rq2->cmd_flags & REQ_META) && !(rq1->cmd_flags & REQ_META))
+ return rq2;
+
+ s1 = blk_rq_pos(rq1);
+ s2 = blk_rq_pos(rq2);
+
+ /*
+ * By definition, 1KiB is 2 sectors.
+ */
+ back_max = bfqd->bfq_back_max * 2;
+
+ /*
+ * Strict one way elevator _except_ in the case where we allow
+ * short backward seeks which are biased as twice the cost of a
+ * similar forward seek.
+ */
+ if (s1 >= last)
+ d1 = s1 - last;
+ else if (s1 + back_max >= last)
+ d1 = (last - s1) * bfqd->bfq_back_penalty;
+ else
+ wrap |= BFQ_RQ1_WRAP;
+
+ if (s2 >= last)
+ d2 = s2 - last;
+ else if (s2 + back_max >= last)
+ d2 = (last - s2) * bfqd->bfq_back_penalty;
+ else
+ wrap |= BFQ_RQ2_WRAP;
+
+ /* Found required data */
+
+ /*
+ * By doing switch() on the bit mask "wrap" we avoid having to
+ * check two variables for all permutations: --> faster!
+ */
+ switch (wrap) {
+ case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
+ if (d1 < d2)
+ return rq1;
+ else if (d2 < d1)
+ return rq2;
+ else {
+ if (s1 >= s2)
+ return rq1;
+ else
+ return rq2;
+ }
+
+ case BFQ_RQ2_WRAP:
+ return rq1;
+ case BFQ_RQ1_WRAP:
+ return rq2;
+ case (BFQ_RQ1_WRAP|BFQ_RQ2_WRAP): /* both rqs wrapped */
+ default:
+ /*
+ * Since both rqs are wrapped,
+ * start with the one that's further behind head
+ * (--> only *one* back seek required),
+ * since back seek takes more time than forward.
+ */
+ if (s1 <= s2)
+ return rq1;
+ else
+ return rq2;
+ }
+}
+
+static struct bfq_queue *
+bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root,
+ sector_t sector, struct rb_node **ret_parent,
+ struct rb_node ***rb_link)
+{
+ struct rb_node **p, *parent;
+ struct bfq_queue *bfqq = NULL;
+
+ parent = NULL;
+ p = &root->rb_node;
+ while (*p) {
+ struct rb_node **n;
+
+ parent = *p;
+ bfqq = rb_entry(parent, struct bfq_queue, pos_node);
+
+ /*
+ * Sort strictly based on sector. Smallest to the left,
+ * largest to the right.
+ */
+ if (sector > blk_rq_pos(bfqq->next_rq))
+ n = &(*p)->rb_right;
+ else if (sector < blk_rq_pos(bfqq->next_rq))
+ n = &(*p)->rb_left;
+ else
+ break;
+ p = n;
+ bfqq = NULL;
+ }
+
+ *ret_parent = parent;
+ if (rb_link)
+ *rb_link = p;
+
+ bfq_log(bfqd, "rq_pos_tree_lookup %llu: returning %d",
+ (long long unsigned)sector,
+ bfqq != NULL ? bfqq->pid : 0);
+
+ return bfqq;
+}
+
+static void bfq_rq_pos_tree_add(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ struct rb_node **p, *parent;
+ struct bfq_queue *__bfqq;
+
+ if (bfqq->pos_root != NULL) {
+ rb_erase(&bfqq->pos_node, bfqq->pos_root);
+ bfqq->pos_root = NULL;
+ }
+
+ if (bfq_class_idle(bfqq))
+ return;
+ if (!bfqq->next_rq)
+ return;
+
+ bfqq->pos_root = &bfqd->rq_pos_tree;
+ __bfqq = bfq_rq_pos_tree_lookup(bfqd, bfqq->pos_root,
+ blk_rq_pos(bfqq->next_rq), &parent, &p);
+ if (__bfqq == NULL) {
+ rb_link_node(&bfqq->pos_node, parent, p);
+ rb_insert_color(&bfqq->pos_node, bfqq->pos_root);
+ } else
+ bfqq->pos_root = NULL;
+}
+
+static struct request *bfq_find_next_rq(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ struct request *last)
+{
+ struct rb_node *rbnext = rb_next(&last->rb_node);
+ struct rb_node *rbprev = rb_prev(&last->rb_node);
+ struct request *next = NULL, *prev = NULL;
+
+ BUG_ON(RB_EMPTY_NODE(&last->rb_node));
+
+ if (rbprev != NULL)
+ prev = rb_entry_rq(rbprev);
+
+ if (rbnext != NULL)
+ next = rb_entry_rq(rbnext);
+ else {
+ rbnext = rb_first(&bfqq->sort_list);
+ if (rbnext && rbnext != &last->rb_node)
+ next = rb_entry_rq(rbnext);
+ }
+
+ return bfq_choose_req(bfqd, next, prev, blk_rq_pos(last));
+}
+
+static void bfq_del_rq_rb(struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+ struct bfq_data *bfqd = bfqq->bfqd;
+ const int sync = rq_is_sync(rq);
+
+ BUG_ON(bfqq->queued[sync] == 0);
+ bfqq->queued[sync]--;
+ bfqd->queued--;
+
+ elv_rb_del(&bfqq->sort_list, rq);
+
+ if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
+ if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->active_queue)
+ bfq_del_bfqq_busy(bfqd, bfqq, 1);
+ /*
+ * Remove queue from request-position tree as it is empty.
+ */
+ if (bfqq->pos_root != NULL) {
+ rb_erase(&bfqq->pos_node, bfqq->pos_root);
+ bfqq->pos_root = NULL;
+ }
+ }
+}
+
+/* see the definition of bfq_async_charge_factor for details */
+static inline unsigned long bfq_serv_to_charge(struct request *rq,
+ struct bfq_queue *bfqq)
+{
+ return blk_rq_sectors(rq) *
+ (1 + ((!bfq_bfqq_sync(bfqq)) * (bfqq->raising_coeff == 1) *
+ bfq_async_charge_factor));
+}
+
+/**
+ * bfq_updated_next_req - update the queue after a new next_rq selection.
+ * @bfqd: the device data the queue belongs to.
+ * @bfqq: the queue to update.
+ *
+ * If the first request of a queue changes we make sure that the queue
+ * has enough budget to serve at least its first request (if the
+ * request has grown). We do this because if the queue has not enough
+ * budget for its first request, it has to go through two dispatch
+ * rounds to actually get it dispatched.
+ */
+static void bfq_updated_next_req(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+ struct bfq_service_tree *st = bfq_entity_service_tree(entity);
+ struct request *next_rq = bfqq->next_rq;
+ unsigned long new_budget;
+
+ if (next_rq == NULL)
+ return;
+
+ if (bfqq == bfqd->active_queue)
+ /*
+ * In order not to break guarantees, budgets cannot be
+ * changed after an entity has been selected.
+ */
+ return;
+
+ BUG_ON(entity->tree != &st->active);
+ BUG_ON(entity == entity->sched_data->active_entity);
+
+ new_budget = max_t(unsigned long, bfqq->max_budget,
+ bfq_serv_to_charge(next_rq, bfqq));
+ entity->budget = new_budget;
+ bfq_log_bfqq(bfqd, bfqq, "updated next rq: new budget %lu", new_budget);
+ bfq_activate_bfqq(bfqd, bfqq);
+}
+
+static inline unsigned int bfq_wrais_duration(struct bfq_data *bfqd)
+{
+ u64 dur;
+
+ if (bfqd->bfq_raising_max_time > 0)
+ return bfqd->bfq_raising_max_time;
+
+ dur = bfqd->RT_prod;
+ do_div(dur, bfqd->peak_rate);
+
+ return dur;
+}
+
+static void bfq_add_rq_rb(struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+ struct bfq_entity *entity = &bfqq->entity;
+ struct bfq_data *bfqd = bfqq->bfqd;
+ struct request *__alias, *next_rq, *prev;
+ unsigned long old_raising_coeff = bfqq->raising_coeff;
+ int idle_for_long_time = bfqq->budget_timeout +
+ bfqd->bfq_raising_min_idle_time < jiffies;
+
+ bfq_log_bfqq(bfqd, bfqq, "add_rq_rb %d", rq_is_sync(rq));
+ bfqq->queued[rq_is_sync(rq)]++;
+ bfqd->queued++;
+
+ /*
+ * Looks a little odd, but the first insert might return an alias,
+ * if that happens, put the alias on the dispatch list.
+ */
+ while ((__alias = elv_rb_add(&bfqq->sort_list, rq)) != NULL)
+ bfq_dispatch_insert(bfqd->queue, __alias);
+
+ /*
+ * Check if this request is a better next-serve candidate.
+ */
+ prev = bfqq->next_rq;
+ next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq, bfqd->last_position);
+ BUG_ON(next_rq == NULL);
+ bfqq->next_rq = next_rq;
+
+ /*
+ * Adjust priority tree position, if next_rq changes.
+ */
+ if (prev != bfqq->next_rq)
+ bfq_rq_pos_tree_add(bfqd, bfqq);
+
+ if (!bfq_bfqq_busy(bfqq)) {
+ int soft_rt = bfqd->bfq_raising_max_softrt_rate > 0 &&
+ bfqq->soft_rt_next_start < jiffies;
+ entity->budget = max_t(unsigned long, bfqq->max_budget,
+ bfq_serv_to_charge(next_rq, bfqq));
+
+ if (! bfqd->low_latency)
+ goto add_bfqq_busy;
+
+ /*
+ * If the queue is not being boosted and has been idle
+ * for enough time, start a weight-raising period
+ */
+ if(old_raising_coeff == 1 && (idle_for_long_time || soft_rt)) {
+ bfqq->raising_coeff = bfqd->bfq_raising_coeff;
+ if (idle_for_long_time)
+ bfqq->raising_cur_max_time =
+ bfq_wrais_duration(bfqd);
+ else
+ bfqq->raising_cur_max_time =
+ bfqd->bfq_raising_rt_max_time;
+ bfq_log_bfqq(bfqd, bfqq,
+ "wrais starting at %llu msec,"
+ "rais_max_time %u",
+ bfqq->last_rais_start_finish,
+ jiffies_to_msecs(bfqq->
+ raising_cur_max_time));
+ } else if (old_raising_coeff > 1) {
+ if (idle_for_long_time)
+ bfqq->raising_cur_max_time =
+ bfq_wrais_duration(bfqd);
+ else if (bfqq->raising_cur_max_time ==
+ bfqd->bfq_raising_rt_max_time &&
+ !soft_rt) {
+ bfqq->raising_coeff = 1;
+ bfq_log_bfqq(bfqd, bfqq,
+ "wrais ending at %llu msec,"
+ "rais_max_time %u",
+ bfqq->last_rais_start_finish,
+ jiffies_to_msecs(bfqq->
+ raising_cur_max_time));
+ }
+ }
+ if (old_raising_coeff != bfqq->raising_coeff)
+ entity->ioprio_changed = 1;
+add_bfqq_busy:
+ bfq_add_bfqq_busy(bfqd, bfqq);
+ } else {
+ if(bfqd->low_latency && old_raising_coeff == 1 &&
+ !rq_is_sync(rq) &&
+ bfqq->last_rais_start_finish +
+ bfqd->bfq_raising_min_inter_arr_async < jiffies) {
+ bfqq->raising_coeff = bfqd->bfq_raising_coeff;
+ bfqq->raising_cur_max_time = bfq_wrais_duration(bfqd);
+
+ entity->ioprio_changed = 1;
+ bfq_log_bfqq(bfqd, bfqq,
+ "non-idle wrais starting at %llu msec,"
+ "rais_max_time %u",
+ bfqq->last_rais_start_finish,
+ jiffies_to_msecs(bfqq->
+ raising_cur_max_time));
+ }
+ bfq_updated_next_req(bfqd, bfqq);
+ }
+
+ if(bfqd->low_latency &&
+ (old_raising_coeff == 1 || bfqq->raising_coeff == 1 ||
+ idle_for_long_time))
+ bfqq->last_rais_start_finish = jiffies;
+}
+
+static void bfq_reposition_rq_rb(struct bfq_queue *bfqq, struct request *rq)
+{
+ elv_rb_del(&bfqq->sort_list, rq);
+ bfqq->queued[rq_is_sync(rq)]--;
+ bfqq->bfqd->queued--;
+ bfq_add_rq_rb(rq);
+}
+
+static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd,
+ struct bio *bio)
+{
+ struct task_struct *tsk = current;
+ struct cfq_io_context *cic;
+ struct bfq_queue *bfqq;
+
+ cic = bfq_cic_lookup(bfqd, tsk->io_context);
+ if (cic == NULL)
+ return NULL;
+
+ bfqq = cic_to_bfqq(cic, bfq_bio_sync(bio));
+ if (bfqq != NULL) {
+ sector_t sector = bio->bi_sector + bio_sectors(bio);
+
+ return elv_rb_find(&bfqq->sort_list, sector);
+ }
+
+ return NULL;
+}
+
+static void bfq_activate_request(struct request_queue *q, struct request *rq)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+
+ bfqd->rq_in_driver++;
+ bfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
+ bfq_log(bfqd, "activate_request: new bfqd->last_position %llu",
+ (long long unsigned)bfqd->last_position);
+}
+
+static void bfq_deactivate_request(struct request_queue *q, struct request *rq)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+
+ WARN_ON(bfqd->rq_in_driver == 0);
+ bfqd->rq_in_driver--;
+}
+
+static void bfq_remove_request(struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+ struct bfq_data *bfqd = bfqq->bfqd;
+
+ if (bfqq->next_rq == rq) {
+ bfqq->next_rq = bfq_find_next_rq(bfqd, bfqq, rq);
+ bfq_updated_next_req(bfqd, bfqq);
+ }
+
+ list_del_init(&rq->queuelist);
+ bfq_del_rq_rb(rq);
+
+ if (rq->cmd_flags & REQ_META) {
+ WARN_ON(bfqq->meta_pending == 0);
+ bfqq->meta_pending--;
+ }
+}
+
+static int bfq_merge(struct request_queue *q, struct request **req,
+ struct bio *bio)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct request *__rq;
+
+ __rq = bfq_find_rq_fmerge(bfqd, bio);
+ if (__rq != NULL && elv_rq_merge_ok(__rq, bio)) {
+ *req = __rq;
+ return ELEVATOR_FRONT_MERGE;
+ }
+
+ return ELEVATOR_NO_MERGE;
+}
+
+static void bfq_merged_request(struct request_queue *q, struct request *req,
+ int type)
+{
+ if (type == ELEVATOR_FRONT_MERGE) {
+ struct bfq_queue *bfqq = RQ_BFQQ(req);
+
+ bfq_reposition_rq_rb(bfqq, req);
+ }
+}
+
+static void bfq_merged_requests(struct request_queue *q, struct request *rq,
+ struct request *next)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+
+ /*
+ * Reposition in fifo if next is older than rq.
+ */
+ if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
+ time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
+ list_move(&rq->queuelist, &next->queuelist);
+ rq_set_fifo_time(rq, rq_fifo_time(next));
+ }
+
+ if (bfqq->next_rq == next)
+ bfqq->next_rq = rq;
+
+ bfq_remove_request(next);
+}
+
+static int bfq_allow_merge(struct request_queue *q, struct request *rq,
+ struct bio *bio)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct cfq_io_context *cic;
+ struct bfq_queue *bfqq;
+
+ /* Disallow merge of a sync bio into an async request. */
+ if (bfq_bio_sync(bio) && !rq_is_sync(rq))
+ return 0;
+
+ /*
+ * Lookup the bfqq that this bio will be queued with. Allow
+ * merge only if rq is queued there.
+ */
+ cic = bfq_cic_lookup(bfqd, current->io_context);
+ if (cic == NULL)
+ return 0;
+
+ bfqq = cic_to_bfqq(cic, bfq_bio_sync(bio));
+ return bfqq == RQ_BFQQ(rq);
+}
+
+static void __bfq_set_active_queue(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ if (bfqq != NULL) {
+ bfq_mark_bfqq_must_alloc(bfqq);
+ bfq_mark_bfqq_budget_new(bfqq);
+ bfq_clear_bfqq_fifo_expire(bfqq);
+
+ bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8;
+
+ bfq_log_bfqq(bfqd, bfqq, "set_active_queue, cur-budget = %lu",
+ bfqq->entity.budget);
+ }
+
+ bfqd->active_queue = bfqq;
+}
+
+/*
+ * Get and set a new active queue for service.
+ */
+static struct bfq_queue *bfq_set_active_queue(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ if (!bfqq)
+ bfqq = bfq_get_next_queue(bfqd);
+ else
+ bfq_get_next_queue_forced(bfqd, bfqq);
+
+ __bfq_set_active_queue(bfqd, bfqq);
+ return bfqq;
+}
+
+static inline sector_t bfq_dist_from_last(struct bfq_data *bfqd,
+ struct request *rq)
+{
+ if (blk_rq_pos(rq) >= bfqd->last_position)
+ return blk_rq_pos(rq) - bfqd->last_position;
+ else
+ return bfqd->last_position - blk_rq_pos(rq);
+}
+
+/*
+ * Return true if bfqq has no request pending and rq is close enough to
+ * bfqd->last_position, or if rq is closer to bfqd->last_position than
+ * bfqq->next_rq
+ */
+static inline int bfq_rq_close(struct bfq_data *bfqd, struct request *rq)
+{
+ return bfq_dist_from_last(bfqd, rq) <= BFQQ_SEEK_THR;
+}
+
+static struct bfq_queue *bfqq_close(struct bfq_data *bfqd)
+{
+ struct rb_root *root = &bfqd->rq_pos_tree;
+ struct rb_node *parent, *node;
+ struct bfq_queue *__bfqq;
+ sector_t sector = bfqd->last_position;
+
+ if (RB_EMPTY_ROOT(root))
+ return NULL;
+
+ /*
+ * First, if we find a request starting at the end of the last
+ * request, choose it.
+ */
+ __bfqq = bfq_rq_pos_tree_lookup(bfqd, root, sector, &parent, NULL);
+ if (__bfqq != NULL)
+ return __bfqq;
+
+ /*
+ * If the exact sector wasn't found, the parent of the NULL leaf
+ * will contain the closest sector (rq_pos_tree sorted by next_request
+ * position).
+ */
+ __bfqq = rb_entry(parent, struct bfq_queue, pos_node);
+ if (bfq_rq_close(bfqd, __bfqq->next_rq))
+ return __bfqq;
+
+ if (blk_rq_pos(__bfqq->next_rq) < sector)
+ node = rb_next(&__bfqq->pos_node);
+ else
+ node = rb_prev(&__bfqq->pos_node);
+ if (node == NULL)
+ return NULL;
+
+ __bfqq = rb_entry(node, struct bfq_queue, pos_node);
+ if (bfq_rq_close(bfqd, __bfqq->next_rq))
+ return __bfqq;
+
+ return NULL;
+}
+
+/*
+ * bfqd - obvious
+ * cur_bfqq - passed in so that we don't decide that the current queue
+ * is closely cooperating with itself.
+ *
+ * We are assuming that cur_bfqq has dispatched at least one request,
+ * and that bfqd->last_position reflects a position on the disk associated
+ * with the I/O issued by cur_bfqq.
+ */
+static struct bfq_queue *bfq_close_cooperator(struct bfq_data *bfqd,
+ struct bfq_queue *cur_bfqq)
+{
+ struct bfq_queue *bfqq;
+
+ if (bfq_class_idle(cur_bfqq))
+ return NULL;
+ if (!bfq_bfqq_sync(cur_bfqq))
+ return NULL;
+ if (BFQQ_SEEKY(cur_bfqq))
+ return NULL;
+
+ /* If device has only one backlogged bfq_queue, don't search. */
+ if (bfqd->busy_queues == 1)
+ return NULL;
+
+ /*
+ * We should notice if some of the queues are cooperating, e.g.
+ * working closely on the same area of the disk. In that case,
+ * we can group them together and don't waste time idling.
+ */
+ bfqq = bfqq_close(bfqd);
+ if (bfqq == NULL || bfqq == cur_bfqq)
+ return NULL;
+
+ /*
+ * Do not merge queues from different bfq_groups.
+ */
+ if (bfqq->entity.parent != cur_bfqq->entity.parent)
+ return NULL;
+
+ /*
+ * It only makes sense to merge sync queues.
+ */
+ if (!bfq_bfqq_sync(bfqq))
+ return NULL;
+ if (BFQQ_SEEKY(bfqq))
+ return NULL;
+
+ /*
+ * Do not merge queues of different priority classes.
+ */
+ if (bfq_class_rt(bfqq) != bfq_class_rt(cur_bfqq))
+ return NULL;
+
+ return bfqq;
+}
+
+/*
+ * If enough samples have been computed, return the current max budget
+ * stored in bfqd, which is dynamically updated according to the
+ * estimated disk peak rate; otherwise return the default max budget
+ */
+static inline unsigned long bfq_max_budget(struct bfq_data *bfqd)
+{
+ if (bfqd->budgets_assigned < 194)
+ return bfq_default_max_budget;
+ else
+ return bfqd->bfq_max_budget;
+}
+
+/*
+ * Return min budget, which is a fraction of the current or default
+ * max budget (trying with 1/32)
+ */
+static inline unsigned long bfq_min_budget(struct bfq_data *bfqd)
+{
+ if (bfqd->budgets_assigned < 194)
+ return bfq_default_max_budget / 32;
+ else
+ return bfqd->bfq_max_budget / 32;
+}
+
+/*
+ * Decides whether idling should be done for given device and
+ * given active queue.
+ */
+static inline bool bfq_queue_nonrot_noidle(struct bfq_data *bfqd,
+ struct bfq_queue *active_bfqq)
+{
+ if (active_bfqq == NULL)
+ return false;
+ /*
+ * If device is SSD it has no seek penalty, disable idling; but
+ * do so only if:
+ * - device does not support queuing, otherwise we still have
+ * a problem with sync vs async workloads;
+ * - the queue is not weight-raised, to preserve guarantees.
+ */
+ return (blk_queue_nonrot(bfqd->queue) && bfqd->hw_tag &&
+ active_bfqq->raising_coeff == 1);
+}
+
+static void bfq_arm_slice_timer(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq = bfqd->active_queue;
+ struct cfq_io_context *cic;
+ unsigned long sl;
+
+ WARN_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
+
+ if (bfq_queue_nonrot_noidle(bfqd, bfqq))
+ return;
+
+ /* Idling is disabled, either manually or by past process history. */
+ if (bfqd->bfq_slice_idle == 0 || !bfq_bfqq_idle_window(bfqq))
+ return;
+
+ /* Tasks have exited, don't wait. */
+ cic = bfqd->active_cic;
+ if (cic == NULL || atomic_read(&cic->ioc->nr_tasks) == 0)
+ return;
+
+ bfq_mark_bfqq_wait_request(bfqq);
+
+ /*
+ * We don't want to idle for seeks, but we do want to allow
+ * fair distribution of slice time for a process doing back-to-back
+ * seeks. So allow a little bit of time for him to submit a new rq.
+ *
+ * To prevent processes with (partly) seeky workloads from
+ * being too ill-treated, grant them a small fraction of the
+ * assigned budget before reducing the waiting time to
+ * BFQ_MIN_TT. This happened to help reduce latency.
+ */
+ sl = bfqd->bfq_slice_idle;
+ if (bfq_sample_valid(bfqq->seek_samples) && BFQQ_SEEKY(bfqq) &&
+ bfqq->entity.service > bfq_max_budget(bfqd) / 8 &&
+ bfqq->raising_coeff == 1)
+ sl = min(sl, msecs_to_jiffies(BFQ_MIN_TT));
+ else if (bfqq->raising_coeff > 1)
+ sl = sl * 3;
+ bfqd->last_idling_start = ktime_get();
+ mod_timer(&bfqd->idle_slice_timer, jiffies + sl);
+ bfq_log(bfqd, "arm idle: %u/%u ms",
+ jiffies_to_msecs(sl), jiffies_to_msecs(bfqd->bfq_slice_idle));
+}
+
+/*
+ * Set the maximum time for the active queue to consume its
+ * budget. This prevents seeky processes from lowering the disk
+ * throughput (always guaranteed with a time slice scheme as in CFQ).
+ */
+static void bfq_set_budget_timeout(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq = bfqd->active_queue;
+ unsigned int timeout_coeff;
+ if (bfqq->raising_cur_max_time == bfqd->bfq_raising_rt_max_time)
+ timeout_coeff = 1;
+ else
+ timeout_coeff = bfqq->entity.weight / bfqq->entity.orig_weight;
+
+ bfqd->last_budget_start = ktime_get();
+
+ bfq_clear_bfqq_budget_new(bfqq);
+ bfqq->budget_timeout = jiffies +
+ bfqd->bfq_timeout[bfq_bfqq_sync(bfqq)] * timeout_coeff;
+
+ bfq_log_bfqq(bfqd, bfqq, "set budget_timeout %u",
+ jiffies_to_msecs(bfqd->bfq_timeout[bfq_bfqq_sync(bfqq)] *
+ timeout_coeff));
+}
+
+/*
+ * Move request from internal lists to the request queue dispatch list.
+ */
+static void bfq_dispatch_insert(struct request_queue *q, struct request *rq)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+
+ bfq_remove_request(rq);
+ bfqq->dispatched++;
+ elv_dispatch_sort(q, rq);
+
+ if (bfq_bfqq_sync(bfqq))
+ bfqd->sync_flight++;
+}
+
+/*
+ * Return expired entry, or NULL to just start from scratch in rbtree.
+ */
+static struct request *bfq_check_fifo(struct bfq_queue *bfqq)
+{
+ struct request *rq = NULL;
+
+ if (bfq_bfqq_fifo_expire(bfqq))
+ return NULL;
+
+ bfq_mark_bfqq_fifo_expire(bfqq);
+
+ if (list_empty(&bfqq->fifo))
+ return NULL;
+
+ rq = rq_entry_fifo(bfqq->fifo.next);
+
+ if (time_before(jiffies, rq_fifo_time(rq)))
+ return NULL;
+
+ return rq;
+}
+
+/*
+ * Must be called with the queue_lock held.
+ */
+static int bfqq_process_refs(struct bfq_queue *bfqq)
+{
+ int process_refs, io_refs;
+
+ io_refs = bfqq->allocated[READ] + bfqq->allocated[WRITE];
+ process_refs = atomic_read(&bfqq->ref) - io_refs - bfqq->entity.on_st;
+ BUG_ON(process_refs < 0);
+ return process_refs;
+}
+
+static void bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
+{
+ int process_refs, new_process_refs;
+ struct bfq_queue *__bfqq;
+
+ /*
+ * If there are no process references on the new_bfqq, then it is
+ * unsafe to follow the ->new_bfqq chain as other bfqq's in the chain
+ * may have dropped their last reference (not just their last process
+ * reference).
+ */
+ if (!bfqq_process_refs(new_bfqq))
+ return;
+
+ /* Avoid a circular list and skip interim queue merges. */
+ while ((__bfqq = new_bfqq->new_bfqq)) {
+ if (__bfqq == bfqq)
+ return;
+ new_bfqq = __bfqq;
+ }
+
+ process_refs = bfqq_process_refs(bfqq);
+ new_process_refs = bfqq_process_refs(new_bfqq);
+ /*
+ * If the process for the bfqq has gone away, there is no
+ * sense in merging the queues.
+ */
+ if (process_refs == 0 || new_process_refs == 0)
+ return;
+
+ /*
+ * Merge in the direction of the lesser amount of work.
+ */
+ if (new_process_refs >= process_refs) {
+ bfqq->new_bfqq = new_bfqq;
+ atomic_add(process_refs, &new_bfqq->ref);
+ } else {
+ new_bfqq->new_bfqq = bfqq;
+ atomic_add(new_process_refs, &bfqq->ref);
+ }
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "scheduling merge with queue %d",
+ new_bfqq->pid);
+}
+
+static inline unsigned long bfq_bfqq_budget_left(struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+ return entity->budget - entity->service;
+}
+
+static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ BUG_ON(bfqq != bfqd->active_queue);
+
+ __bfq_bfqd_reset_active(bfqd);
+
+ if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
+ bfq_del_bfqq_busy(bfqd, bfqq, 1);
+ /*
+ * overloading budget_timeout field to store when
+ * the queue remains with no backlog, used by
+ * the weight-raising mechanism
+ */
+ bfqq->budget_timeout = jiffies ;
+ }
+ else {
+ bfq_activate_bfqq(bfqd, bfqq);
+ /*
+ * Resort priority tree of potential close cooperators.
+ */
+ bfq_rq_pos_tree_add(bfqd, bfqq);
+ }
+
+ /*
+ * If this bfqq is shared between multiple processes, check
+ * to make sure that those processes are still issuing I/Os
+ * within the mean seek distance. If not, it may be time to
+ * break the queues apart again.
+ */
+ if (bfq_bfqq_coop(bfqq) && BFQQ_SEEKY(bfqq))
+ bfq_mark_bfqq_split_coop(bfqq);
+}
+
+/**
+ * __bfq_bfqq_recalc_budget - try to adapt the budget to the @bfqq behavior.
+ * @bfqd: device data.
+ * @bfqq: queue to update.
+ * @reason: reason for expiration.
+ *
+ * Handle the feedback on @bfqq budget. See the body for detailed
+ * comments.
+ */
+static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ enum bfqq_expiration reason)
+{
+ struct request *next_rq;
+ unsigned long budget, min_budget;
+
+ budget = bfqq->max_budget;
+ min_budget = bfq_min_budget(bfqd);
+
+ BUG_ON(bfqq != bfqd->active_queue);
+
+ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last budg %lu, budg left %lu",
+ bfqq->entity.budget, bfq_bfqq_budget_left(bfqq));
+ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last max_budg %lu, min budg %lu",
+ budget, bfq_min_budget(bfqd));
+ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: sync %d, seeky %d",
+ bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->active_queue));
+
+ if (bfq_bfqq_sync(bfqq)) {
+ switch (reason) {
+ /*
+ * Caveat: in all the following cases we trade latency
+ * for throughput.
+ */
+ case BFQ_BFQQ_TOO_IDLE:
+ /*
+ * This is the only case where we may reduce
+ * the budget: if there is no requets of the
+ * process still waiting for completion, then
+ * we assume (tentatively) that the timer has
+ * expired because the batch of requests of
+ * the process could have been served with a
+ * smaller budget. Hence, betting that
+ * process will behave in the same way when it
+ * becomes backlogged again, we reduce its
+ * next budget. As long as we guess right,
+ * this budget cut reduces the latency
+ * experienced by the process.
+ *
+ * However, if there are still outstanding
+ * requests, then the process may have not yet
+ * issued its next request just because it is
+ * still waiting for the completion of some of
+ * the still oustanding ones. So in this
+ * subcase we do not reduce its budget, on the
+ * contrary we increase it to possibly boost
+ * the throughput, as discussed in the
+ * comments to the BUDGET_TIMEOUT case.
+ */
+ if (bfqq->dispatched > 0) /* still oustanding reqs */
+ budget = min(budget * 2, bfqd->bfq_max_budget);
+ else {
+ if (budget > 5 * min_budget)
+ budget -= 4 * min_budget;
+ else
+ budget = min_budget;
+ }
+ break;
+ case BFQ_BFQQ_BUDGET_TIMEOUT:
+ /*
+ * We double the budget here because: 1) it
+ * gives the chance to boost the throughput if
+ * this is not a seeky process (which may have
+ * bumped into this timeout because of, e.g.,
+ * ZBR), 2) together with charge_full_budget
+ * it helps give seeky processes higher
+ * timestamps, and hence be served less
+ * frequently.
+ */
+ budget = min(budget * 2, bfqd->bfq_max_budget);
+ break;
+ case BFQ_BFQQ_BUDGET_EXHAUSTED:
+ /*
+ * The process still has backlog, and did not
+ * let either the budget timeout or the disk
+ * idling timeout expire. Hence it is not
+ * seeky, has a short thinktime and may be
+ * happy with a higher budget too. So
+ * definitely increase the budget of this good
+ * candidate to boost the disk throughput.
+ */
+ budget = min(budget * 4, bfqd->bfq_max_budget);
+ break;
+ case BFQ_BFQQ_NO_MORE_REQUESTS:
+ /*
+ * Leave the budget unchanged.
+ */
+ default:
+ return;
+ }
+ } else /* async queue */
+ /* async queues get always the maximum possible budget
+ * (their ability to dispatch is limited by
+ * @bfqd->bfq_max_budget_async_rq).
+ */
+ budget = bfqd->bfq_max_budget;
+
+ bfqq->max_budget = budget;
+
+ if (bfqd->budgets_assigned >= 194 && bfqd->bfq_user_max_budget == 0 &&
+ bfqq->max_budget > bfqd->bfq_max_budget)
+ bfqq->max_budget = bfqd->bfq_max_budget;
+
+ /*
+ * Make sure that we have enough budget for the next request.
+ * Since the finish time of the bfqq must be kept in sync with
+ * the budget, be sure to call __bfq_bfqq_expire() after the
+ * update.
+ */
+ next_rq = bfqq->next_rq;
+ if (next_rq != NULL)
+ bfqq->entity.budget = max_t(unsigned long, bfqq->max_budget,
+ bfq_serv_to_charge(next_rq, bfqq));
+ else
+ bfqq->entity.budget = bfqq->max_budget;
+
+ bfq_log_bfqq(bfqd, bfqq, "head sect: %u, new budget %lu",
+ next_rq != NULL ? blk_rq_sectors(next_rq) : 0,
+ bfqq->entity.budget);
+}
+
+static unsigned long bfq_calc_max_budget(u64 peak_rate, u64 timeout)
+{
+ unsigned long max_budget;
+
+ /*
+ * The max_budget calculated when autotuning is equal to the
+ * amount of sectors transfered in timeout_sync at the
+ * estimated peak rate.
+ */
+ max_budget = (unsigned long)(peak_rate * 1000 *
+ timeout >> BFQ_RATE_SHIFT);
+
+ return max_budget;
+}
+
+/*
+ * In addition to updating the peak rate, checks whether the process
+ * is "slow", and returns 1 if so. This slow flag is used, in addition
+ * to the budget timeout, to reduce the amount of service provided to
+ * seeky processes, and hence reduce their chances to lower the
+ * throughput. See the code for more details.
+ */
+static int bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ int compensate, enum bfqq_expiration reason)
+{
+ u64 bw, usecs, expected, timeout;
+ ktime_t delta;
+ int update = 0;
+
+ if (!bfq_bfqq_sync(bfqq) || bfq_bfqq_budget_new(bfqq))
+ return 0;
+
+ if (compensate)
+ delta = bfqd->last_idling_start;
+ else
+ delta = ktime_get();
+ delta = ktime_sub(delta, bfqd->last_budget_start);
+ usecs = ktime_to_us(delta);
+
+ /* Don't trust short/unrealistic values. */
+ if (usecs < 100 || usecs >= LONG_MAX)
+ return 0;
+
+ /*
+ * Calculate the bandwidth for the last slice. We use a 64 bit
+ * value to store the peak rate, in sectors per usec in fixed
+ * point math. We do so to have enough precision in the estimate
+ * and to avoid overflows.
+ */
+ bw = (u64)bfqq->entity.service << BFQ_RATE_SHIFT;
+ do_div(bw, (unsigned long)usecs);
+
+ timeout = jiffies_to_msecs(bfqd->bfq_timeout[BLK_RW_SYNC]);
+
+ /*
+ * Use only long (> 20ms) intervals to filter out spikes for
+ * the peak rate estimation.
+ */
+ if (usecs > 20000) {
+ if (bw > bfqd->peak_rate ||
+ (!BFQQ_SEEKY(bfqq) &&
+ reason == BFQ_BFQQ_BUDGET_TIMEOUT)) {
+ bfq_log(bfqd, "measured bw =%llu", bw);
+ /*
+ * To smooth oscillations use a low-pass filter with
+ * alpha=7/8, i.e.,
+ * new_rate = (7/8) * old_rate + (1/8) * bw
+ */
+ do_div(bw, 8);
+ bfqd->peak_rate *= 7;
+ do_div(bfqd->peak_rate, 8);
+ bfqd->peak_rate += bw;
+ update = 1;
+ bfq_log(bfqd, "new peak_rate=%llu", bfqd->peak_rate);
+ }
+
+ update |= bfqd->peak_rate_samples == BFQ_PEAK_RATE_SAMPLES - 1;
+
+ if (bfqd->peak_rate_samples < BFQ_PEAK_RATE_SAMPLES)
+ bfqd->peak_rate_samples++;
+
+ if (bfqd->peak_rate_samples == BFQ_PEAK_RATE_SAMPLES &&
+ update && bfqd->bfq_user_max_budget == 0) {
+ bfqd->bfq_max_budget =
+ bfq_calc_max_budget(bfqd->peak_rate, timeout);
+ bfq_log(bfqd, "new max_budget=%lu",
+ bfqd->bfq_max_budget);
+ }
+ }
+
+ /*
+ * If the process has been served for a too short time
+ * interval to let its possible sequential accesses prevail on
+ * the initial seek time needed to move the disk head on the
+ * first sector it requested, then give the process a chance
+ * and for the moment return false.
+ */
+ if (bfqq->entity.budget <= bfq_max_budget(bfqd) / 8)
+ return 0;
+
+ /*
+ * A process is considered ``slow'' (i.e., seeky, so that we
+ * cannot treat it fairly in the service domain, as it would
+ * slow down too much the other processes) if, when a slice
+ * ends for whatever reason, it has received service at a
+ * rate that would not be high enough to complete the budget
+ * before the budget timeout expiration.
+ */
+ expected = bw * 1000 * timeout >> BFQ_RATE_SHIFT;
+
+ /*
+ * Caveat: processes doing IO in the slower disk zones will
+ * tend to be slow(er) even if not seeky. And the estimated
+ * peak rate will actually be an average over the disk
+ * surface. Hence, to not be too harsh with unlucky processes,
+ * we keep a budget/3 margin of safety before declaring a
+ * process slow.
+ */
+ return expected > (4 * bfqq->entity.budget) / 3;
+}
+
+/**
+ * bfq_bfqq_expire - expire a queue.
+ * @bfqd: device owning the queue.
+ * @bfqq: the queue to expire.
+ * @compensate: if true, compensate for the time spent idling.
+ * @reason: the reason causing the expiration.
+ *
+ *
+ * If the process associated to the queue is slow (i.e., seeky), or in
+ * case of budget timeout, or, finally, if it is async, we
+ * artificially charge it an entire budget (independently of the
+ * actual service it received). As a consequence, the queue will get
+ * higher timestamps than the correct ones upon reactivation, and
+ * hence it will be rescheduled as if it had received more service
+ * than what it actually received. In the end, this class of processes
+ * will receive less service in proportion to how slowly they consume
+ * their budgets (and hence how seriously they tend to lower the
+ * throughput).
+ *
+ * In contrast, when a queue expires because it has been idling for
+ * too much or because it exhausted its budget, we do not touch the
+ * amount of service it has received. Hence when the queue will be
+ * reactivated and its timestamps updated, the latter will be in sync
+ * with the actual service received by the queue until expiration.
+ *
+ * Charging a full budget to the first type of queues and the exact
+ * service to the others has the effect of using the WF2Q+ policy to
+ * schedule the former on a timeslice basis, without violating the
+ * service domain guarantees of the latter.
+ */
+static void bfq_bfqq_expire(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ int compensate,
+ enum bfqq_expiration reason)
+{
+ int slow;
+ BUG_ON(bfqq != bfqd->active_queue);
+
+ /* Update disk peak rate for autotuning and check whether the
+ * process is slow (see bfq_update_peak_rate).
+ */
+ slow = bfq_update_peak_rate(bfqd, bfqq, compensate, reason);
+
+ /*
+ * As above explained, 'punish' slow (i.e., seeky), timed-out
+ * and async queues, to favor sequential sync workloads.
+ *
+ * Processes doing IO in the slower disk zones will tend to be
+ * slow(er) even if not seeky. Hence, since the estimated peak
+ * rate is actually an average over the disk surface, these
+ * processes may timeout just for bad luck. To avoid punishing
+ * them we do not charge a full budget to a process that
+ * succeeded in consuming at least 2/3 of its budget.
+ */
+ if (slow || (reason == BFQ_BFQQ_BUDGET_TIMEOUT &&
+ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3))
+ bfq_bfqq_charge_full_budget(bfqq);
+
+ if (bfqd->low_latency && bfqq->raising_coeff == 1)
+ bfqq->last_rais_start_finish = jiffies;
+
+ if (bfqd->low_latency && bfqd->bfq_raising_max_softrt_rate > 0) {
+ if(reason != BFQ_BFQQ_BUDGET_TIMEOUT)
+ bfqq->soft_rt_next_start =
+ jiffies +
+ HZ * bfqq->entity.service /
+ bfqd->bfq_raising_max_softrt_rate;
+ else
+ bfqq->soft_rt_next_start = -1; /* infinity */
+ }
+ bfq_log_bfqq(bfqd, bfqq,
+ "expire (%d, slow %d, num_disp %d, idle_win %d)", reason, slow,
+ bfqq->dispatched, bfq_bfqq_idle_window(bfqq));
+
+ /* Increase, decrease or leave budget unchanged according to reason */
+ __bfq_bfqq_recalc_budget(bfqd, bfqq, reason);
+ __bfq_bfqq_expire(bfqd, bfqq);
+}
+
+/*
+ * Budget timeout is not implemented through a dedicated timer, but
+ * just checked on request arrivals and completions, as well as on
+ * idle timer expirations.
+ */
+static int bfq_bfqq_budget_timeout(struct bfq_queue *bfqq)
+{
+ if (bfq_bfqq_budget_new(bfqq))
+ return 0;
+
+ if (time_before(jiffies, bfqq->budget_timeout))
+ return 0;
+
+ return 1;
+}
+
+/*
+ * If we expire a queue that is waiting for the arrival of a new
+ * request, we may prevent the fictitious timestamp backshifting that
+ * allows the guarantees of the queue to be preserved (see [1] for
+ * this tricky aspect). Hence we return true only if this condition
+ * does not hold, or if the queue is slow enough to deserve only to be
+ * kicked off for preserving a high throughput.
+*/
+static inline int bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq)
+{
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "may_budget_timeout: wr %d left %d timeout %d",
+ bfq_bfqq_wait_request(bfqq),
+ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3,
+ bfq_bfqq_budget_timeout(bfqq));
+
+ return (!bfq_bfqq_wait_request(bfqq) ||
+ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3)
+ &&
+ bfq_bfqq_budget_timeout(bfqq);
+}
+
+/*
+ * Select a queue for service. If we have a current active queue,
+ * check whether to continue servicing it, or retrieve and set a new one.
+ */
+static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq, *new_bfqq = NULL;
+ struct request *next_rq;
+ enum bfqq_expiration reason = BFQ_BFQQ_BUDGET_TIMEOUT;
+
+ bfqq = bfqd->active_queue;
+ if (bfqq == NULL)
+ goto new_queue;
+
+ bfq_log_bfqq(bfqd, bfqq, "select_queue: already active queue");
+
+ /*
+ * If another queue has a request waiting within our mean seek
+ * distance, let it run. The expire code will check for close
+ * cooperators and put the close queue at the front of the
+ * service tree. If possible, merge the expiring queue with the
+ * new bfqq.
+ */
+ new_bfqq = bfq_close_cooperator(bfqd, bfqq);
+ if (new_bfqq != NULL && bfqq->new_bfqq == NULL)
+ bfq_setup_merge(bfqq, new_bfqq);
+
+ if (bfq_may_expire_for_budg_timeout(bfqq))
+ goto expire;
+
+ next_rq = bfqq->next_rq;
+ /*
+ * If bfqq has requests queued and it has enough budget left to
+ * serve them, keep the queue, otherwise expire it.
+ */
+ if (next_rq != NULL) {
+ if (bfq_serv_to_charge(next_rq, bfqq) >
+ bfq_bfqq_budget_left(bfqq)) {
+ reason = BFQ_BFQQ_BUDGET_EXHAUSTED;
+ goto expire;
+ } else {
+ /*
+ * The idle timer may be pending because we may not
+ * disable disk idling even when a new request arrives
+ */
+ if (timer_pending(&bfqd->idle_slice_timer)) {
+ /*
+ * If we get here: 1) at least a new request
+ * has arrived but we have not disabled the
+ * timer because the request was too small,
+ * 2) then the block layer has unplugged the
+ * device, causing the dispatch to be invoked.
+ *
+ * Since the device is unplugged, now the
+ * requests are probably large enough to
+ * provide a reasonable throughput.
+ * So we disable idling.
+ */
+ bfq_clear_bfqq_wait_request(bfqq);
+ del_timer(&bfqd->idle_slice_timer);
+ }
+ if (new_bfqq == NULL)
+ goto keep_queue;
+ else
+ goto expire;
+ }
+ }
+
+ /*
+ * No requests pending. If there is no cooperator, and the active
+ * queue still has requests in flight or is idling for a new request,
+ * then keep it.
+ */
+ if (new_bfqq == NULL && (timer_pending(&bfqd->idle_slice_timer) ||
+ (bfqq->dispatched != 0 && bfq_bfqq_idle_window(bfqq) &&
+ !bfq_queue_nonrot_noidle(bfqd, bfqq)))) {
+ bfqq = NULL;
+ goto keep_queue;
+ } else if (new_bfqq != NULL && timer_pending(&bfqd->idle_slice_timer)) {
+ /*
+ * Expiring the queue because there is a close cooperator,
+ * cancel timer.
+ */
+ bfq_clear_bfqq_wait_request(bfqq);
+ del_timer(&bfqd->idle_slice_timer);
+ }
+
+ reason = BFQ_BFQQ_NO_MORE_REQUESTS;
+expire:
+ bfq_bfqq_expire(bfqd, bfqq, 0, reason);
+new_queue:
+ bfqq = bfq_set_active_queue(bfqd, new_bfqq);
+ bfq_log(bfqd, "select_queue: new queue %d returned",
+ bfqq != NULL ? bfqq->pid : 0);
+keep_queue:
+ return bfqq;
+}
+
+static void update_raising_data(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ if (bfqq->raising_coeff > 1) { /* queue is being boosted */
+ struct bfq_entity *entity = &bfqq->entity;
+
+ bfq_log_bfqq(bfqd, bfqq,
+ "raising period dur %u/%u msec, "
+ "old raising coeff %u, w %d(%d)",
+ jiffies_to_msecs(jiffies -
+ bfqq->last_rais_start_finish),
+ jiffies_to_msecs(bfqq->raising_cur_max_time),
+ bfqq->raising_coeff,
+ bfqq->entity.weight, bfqq->entity.orig_weight);
+
+ BUG_ON(bfqq != bfqd->active_queue && entity->weight !=
+ entity->orig_weight * bfqq->raising_coeff);
+ if(entity->ioprio_changed)
+ bfq_log_bfqq(bfqd, bfqq,
+ "WARN: pending prio change");
+ /*
+ * If too much time has elapsed from the beginning
+ * of this weight-raising period and process is not soft
+ * real-time, stop it
+ */
+ if (jiffies - bfqq->last_rais_start_finish >
+ bfqq->raising_cur_max_time) {
+ int soft_rt = bfqd->bfq_raising_max_softrt_rate > 0 &&
+ bfqq->soft_rt_next_start < jiffies;
+
+ bfqq->last_rais_start_finish = jiffies;
+ if (soft_rt)
+ bfqq->raising_cur_max_time =
+ bfqd->bfq_raising_rt_max_time;
+ else {
+ bfqq->raising_coeff = 1;
+ entity->ioprio_changed = 1;
+ __bfq_entity_update_weight_prio(
+ bfq_entity_service_tree(entity),
+ entity);
+ }
+ }
+ }
+}
+
+
+/*
+ * Dispatch one request from bfqq, moving it to the request queue
+ * dispatch list.
+ */
+static int bfq_dispatch_request(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ int dispatched = 0;
+ struct request *rq;
+ unsigned long service_to_charge;
+
+ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
+
+ /* Follow expired path, else get first next available. */
+ rq = bfq_check_fifo(bfqq);
+ if (rq == NULL)
+ rq = bfqq->next_rq;
+ service_to_charge = bfq_serv_to_charge(rq, bfqq);
+
+ if (service_to_charge > bfq_bfqq_budget_left(bfqq)) {
+ /*
+ * This may happen if the next rq is chosen
+ * in fifo order instead of sector order.
+ * The budget is properly dimensioned
+ * to be always sufficient to serve the next request
+ * only if it is chosen in sector order. The reason is
+ * that it would be quite inefficient and little useful
+ * to always make sure that the budget is large enough
+ * to serve even the possible next rq in fifo order.
+ * In fact, requests are seldom served in fifo order.
+ *
+ * Expire the queue for budget exhaustion, and
+ * make sure that the next act_budget is enough
+ * to serve the next request, even if it comes
+ * from the fifo expired path.
+ */
+ bfqq->next_rq = rq;
+ /*
+ * Since this dispatch is failed, make sure that
+ * a new one will be performed
+ */
+ if (!bfqd->rq_in_driver)
+ bfq_schedule_dispatch(bfqd);
+ goto expire;
+ }
+
+ /* Finally, insert request into driver dispatch list. */
+ bfq_bfqq_served(bfqq, service_to_charge);
+ bfq_dispatch_insert(bfqd->queue, rq);
+
+ update_raising_data(bfqd, bfqq);
+
+ bfq_log_bfqq(bfqd, bfqq, "dispatched %u sec req (%llu), "
+ "budg left %lu",
+ blk_rq_sectors(rq),
+ (long long unsigned)blk_rq_pos(rq),
+ bfq_bfqq_budget_left(bfqq));
+
+ dispatched++;
+
+ if (bfqd->active_cic == NULL) {
+ atomic_long_inc(&RQ_CIC(rq)->ioc->refcount);
+ bfqd->active_cic = RQ_CIC(rq);
+ }
+
+ if (bfqd->busy_queues > 1 && ((!bfq_bfqq_sync(bfqq) &&
+ dispatched >= bfqd->bfq_max_budget_async_rq) ||
+ bfq_class_idle(bfqq)))
+ goto expire;
+
+ return dispatched;
+
+expire:
+ bfq_bfqq_expire(bfqd, bfqq, 0, BFQ_BFQQ_BUDGET_EXHAUSTED);
+ return dispatched;
+}
+
+static int __bfq_forced_dispatch_bfqq(struct bfq_queue *bfqq)
+{
+ int dispatched = 0;
+
+ while (bfqq->next_rq != NULL) {
+ bfq_dispatch_insert(bfqq->bfqd->queue, bfqq->next_rq);
+ dispatched++;
+ }
+
+ BUG_ON(!list_empty(&bfqq->fifo));
+ return dispatched;
+}
+
+/*
+ * Drain our current requests. Used for barriers and when switching
+ * io schedulers on-the-fly.
+ */
+static int bfq_forced_dispatch(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq, *n;
+ struct bfq_service_tree *st;
+ int dispatched = 0;
+
+ bfqq = bfqd->active_queue;
+ if (bfqq != NULL)
+ __bfq_bfqq_expire(bfqd, bfqq);
+
+ /*
+ * Loop through classes, and be careful to leave the scheduler
+ * in a consistent state, as feedback mechanisms and vtime
+ * updates cannot be disabled during the process.
+ */
+ list_for_each_entry_safe(bfqq, n, &bfqd->active_list, bfqq_list) {
+ st = bfq_entity_service_tree(&bfqq->entity);
+
+ dispatched += __bfq_forced_dispatch_bfqq(bfqq);
+ bfqq->max_budget = bfq_max_budget(bfqd);
+
+ bfq_forget_idle(st);
+ }
+
+ BUG_ON(bfqd->busy_queues != 0);
+
+ return dispatched;
+}
+
+static int bfq_dispatch_requests(struct request_queue *q, int force)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct bfq_queue *bfqq;
+ int max_dispatch;
+
+ bfq_log(bfqd, "dispatch requests: %d busy queues", bfqd->busy_queues);
+ if (bfqd->busy_queues == 0)
+ return 0;
+
+ if (unlikely(force))
+ return bfq_forced_dispatch(bfqd);
+
+ if((bfqq = bfq_select_queue(bfqd)) == NULL)
+ return 0;
+
+ max_dispatch = bfqd->bfq_quantum;
+ if (bfq_class_idle(bfqq))
+ max_dispatch = 1;
+
+ if (!bfq_bfqq_sync(bfqq))
+ max_dispatch = bfqd->bfq_max_budget_async_rq;
+
+ if (bfqq->dispatched >= max_dispatch) {
+ if (bfqd->busy_queues > 1)
+ return 0;
+ if (bfqq->dispatched >= 4 * max_dispatch)
+ return 0;
+ }
+
+ if (bfqd->sync_flight != 0 && !bfq_bfqq_sync(bfqq))
+ return 0;
+
+ bfq_clear_bfqq_wait_request(bfqq);
+ BUG_ON(timer_pending(&bfqd->idle_slice_timer));
+
+ if (! bfq_dispatch_request(bfqd, bfqq))
+ return 0;
+
+ bfq_log_bfqq(bfqd, bfqq, "dispatched one request of %d"
+ "(max_disp %d)", bfqq->pid, max_dispatch);
+
+ return 1;
+}
+
+/*
+ * Task holds one reference to the queue, dropped when task exits. Each rq
+ * in-flight on this queue also holds a reference, dropped when rq is freed.
+ *
+ * Queue lock must be held here.
+ */
+static void bfq_put_queue(struct bfq_queue *bfqq)
+{
+ struct bfq_data *bfqd = bfqq->bfqd;
+
+ BUG_ON(atomic_read(&bfqq->ref) <= 0);
+
+ bfq_log_bfqq(bfqd, bfqq, "put_queue: %p %d", bfqq,
+ atomic_read(&bfqq->ref));
+ if (!atomic_dec_and_test(&bfqq->ref))
+ return;
+
+ BUG_ON(rb_first(&bfqq->sort_list) != NULL);
+ BUG_ON(bfqq->allocated[READ] + bfqq->allocated[WRITE] != 0);
+ BUG_ON(bfqq->entity.tree != NULL);
+ BUG_ON(bfq_bfqq_busy(bfqq));
+ BUG_ON(bfqd->active_queue == bfqq);
+
+ bfq_log_bfqq(bfqd, bfqq, "put_queue: %p freed", bfqq);
+
+ kmem_cache_free(bfq_pool, bfqq);
+}
+
+static void bfq_put_cooperator(struct bfq_queue *bfqq)
+{
+ struct bfq_queue *__bfqq, *next;
+
+ /*
+ * If this queue was scheduled to merge with another queue, be
+ * sure to drop the reference taken on that queue (and others in
+ * the merge chain). See bfq_setup_merge and bfq_merge_bfqqs.
+ */
+ __bfqq = bfqq->new_bfqq;
+ while (__bfqq) {
+ if (__bfqq == bfqq) {
+ WARN(1, "bfqq->new_bfqq loop detected.\n");
+ break;
+ }
+ next = __bfqq->new_bfqq;
+ bfq_put_queue(__bfqq);
+ __bfqq = next;
+ }
+}
+
+static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ if (bfqq == bfqd->active_queue) {
+ __bfq_bfqq_expire(bfqd, bfqq);
+ bfq_schedule_dispatch(bfqd);
+ }
+
+ bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq,
+ atomic_read(&bfqq->ref));
+
+ bfq_put_cooperator(bfqq);
+
+ bfq_put_queue(bfqq);
+}
+
+/*
+ * Update the entity prio values; note that the new values will not
+ * be used until the next (re)activation.
+ */
+static void bfq_init_prio_data(struct bfq_queue *bfqq, struct io_context *ioc)
+{
+ struct task_struct *tsk = current;
+ int ioprio_class;
+
+ if (!bfq_bfqq_prio_changed(bfqq))
+ return;
+
+ ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
+ switch (ioprio_class) {
+ default:
+ printk(KERN_ERR "bfq: bad prio %x\n", ioprio_class);
+ case IOPRIO_CLASS_NONE:
+ /*
+ * No prio set, inherit CPU scheduling settings.
+ */
+ bfqq->entity.new_ioprio = task_nice_ioprio(tsk);
+ bfqq->entity.new_ioprio_class = task_nice_ioclass(tsk);
+ break;
+ case IOPRIO_CLASS_RT:
+ bfqq->entity.new_ioprio = task_ioprio(ioc);
+ bfqq->entity.new_ioprio_class = IOPRIO_CLASS_RT;
+ break;
+ case IOPRIO_CLASS_BE:
+ bfqq->entity.new_ioprio = task_ioprio(ioc);
+ bfqq->entity.new_ioprio_class = IOPRIO_CLASS_BE;
+ break;
+ case IOPRIO_CLASS_IDLE:
+ bfqq->entity.new_ioprio_class = IOPRIO_CLASS_IDLE;
+ bfqq->entity.new_ioprio = 7;
+ bfq_clear_bfqq_idle_window(bfqq);
+ break;
+ }
+
+ bfqq->entity.ioprio_changed = 1;
+
+ /*
+ * Keep track of original prio settings in case we have to temporarily
+ * elevate the priority of this queue.
+ */
+ bfqq->org_ioprio = bfqq->entity.new_ioprio;
+ bfqq->org_ioprio_class = bfqq->entity.new_ioprio_class;
+ bfq_clear_bfqq_prio_changed(bfqq);
+}
+
+static void bfq_changed_ioprio(struct io_context *ioc,
+ struct cfq_io_context *cic)
+{
+ struct bfq_data *bfqd;
+ struct bfq_queue *bfqq, *new_bfqq;
+ struct bfq_group *bfqg;
+ unsigned long uninitialized_var(flags);
+
+ bfqd = bfq_get_bfqd_locked(&cic->key, &flags);
+ if (unlikely(bfqd == NULL))
+ return;
+
+ bfqq = cic->cfqq[BLK_RW_ASYNC];
+ if (bfqq != NULL) {
+ bfqg = container_of(bfqq->entity.sched_data, struct bfq_group,
+ sched_data);
+ new_bfqq = bfq_get_queue(bfqd, bfqg, BLK_RW_ASYNC, cic->ioc,
+ GFP_ATOMIC);
+ if (new_bfqq != NULL) {
+ cic->cfqq[BLK_RW_ASYNC] = new_bfqq;
+ bfq_log_bfqq(bfqd, bfqq,
+ "changed_ioprio: bfqq %p %d",
+ bfqq, atomic_read(&bfqq->ref));
+ bfq_put_queue(bfqq);
+ }
+ }
+
+ bfqq = cic->cfqq[BLK_RW_SYNC];
+ if (bfqq != NULL)
+ bfq_mark_bfqq_prio_changed(bfqq);
+
+ bfq_put_bfqd_unlock(bfqd, &flags);
+}
+
+static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ pid_t pid, int is_sync)
+{
+ RB_CLEAR_NODE(&bfqq->entity.rb_node);
+ INIT_LIST_HEAD(&bfqq->fifo);
+
+ atomic_set(&bfqq->ref, 0);
+ bfqq->bfqd = bfqd;
+
+ bfq_mark_bfqq_prio_changed(bfqq);
+
+ if (is_sync) {
+ if (!bfq_class_idle(bfqq))
+ bfq_mark_bfqq_idle_window(bfqq);
+ bfq_mark_bfqq_sync(bfqq);
+ }
+
+ /* Tentative initial value to trade off between thr and lat */
+ bfqq->max_budget = (2 * bfq_max_budget(bfqd)) / 3;
+ bfqq->pid = pid;
+
+ bfqq->raising_coeff = 1;
+ bfqq->last_rais_start_finish = 0;
+ bfqq->soft_rt_next_start = -1;
+}
+
+static struct bfq_queue *bfq_find_alloc_queue(struct bfq_data *bfqd,
+ struct bfq_group *bfqg,
+ int is_sync,
+ struct io_context *ioc,
+ gfp_t gfp_mask)
+{
+ struct bfq_queue *bfqq, *new_bfqq = NULL;
+ struct cfq_io_context *cic;
+
+retry:
+ cic = bfq_cic_lookup(bfqd, ioc);
+ /* cic always exists here */
+ bfqq = cic_to_bfqq(cic, is_sync);
+
+ /*
+ * Always try a new alloc if we fall back to the OOM bfqq
+ * originally, since it should just be a temporary situation.
+ */
+ if (bfqq == NULL || bfqq == &bfqd->oom_bfqq) {
+ bfqq = NULL;
+ if (new_bfqq != NULL) {
+ bfqq = new_bfqq;
+ new_bfqq = NULL;
+ } else if (gfp_mask & __GFP_WAIT) {
+ spin_unlock_irq(bfqd->queue->queue_lock);
+ new_bfqq = kmem_cache_alloc_node(bfq_pool,
+ gfp_mask | __GFP_ZERO,
+ bfqd->queue->node);
+ spin_lock_irq(bfqd->queue->queue_lock);
+ if (new_bfqq != NULL)
+ goto retry;
+ } else {
+ bfqq = kmem_cache_alloc_node(bfq_pool,
+ gfp_mask | __GFP_ZERO,
+ bfqd->queue->node);
+ }
+
+ if (bfqq != NULL) {
+ bfq_init_bfqq(bfqd, bfqq, current->pid, is_sync);
+ bfq_log_bfqq(bfqd, bfqq, "allocated");
+ } else {
+ bfqq = &bfqd->oom_bfqq;
+ bfq_log_bfqq(bfqd, bfqq, "using oom bfqq");
+ }
+
+ bfq_init_prio_data(bfqq, ioc);
+ bfq_init_entity(&bfqq->entity, bfqg);
+ }
+
+ if (new_bfqq != NULL)
+ kmem_cache_free(bfq_pool, new_bfqq);
+
+ return bfqq;
+}
+
+static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd,
+ struct bfq_group *bfqg,
+ int ioprio_class, int ioprio)
+{
+ switch (ioprio_class) {
+ case IOPRIO_CLASS_RT:
+ return &bfqg->async_bfqq[0][ioprio];
+ case IOPRIO_CLASS_BE:
+ return &bfqg->async_bfqq[1][ioprio];
+ case IOPRIO_CLASS_IDLE:
+ return &bfqg->async_idle_bfqq;
+ default:
+ BUG();
+ }
+}
+
+static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
+ struct bfq_group *bfqg, int is_sync,
+ struct io_context *ioc, gfp_t gfp_mask)
+{
+ const int ioprio = task_ioprio(ioc);
+ const int ioprio_class = task_ioprio_class(ioc);
+ struct bfq_queue **async_bfqq = NULL;
+ struct bfq_queue *bfqq = NULL;
+
+ if (!is_sync) {
+ async_bfqq = bfq_async_queue_prio(bfqd, bfqg, ioprio_class,
+ ioprio);
+ bfqq = *async_bfqq;
+ }
+
+ if (bfqq == NULL)
+ bfqq = bfq_find_alloc_queue(bfqd, bfqg, is_sync, ioc, gfp_mask);
+
+ /*
+ * Pin the queue now that it's allocated, scheduler exit will prune it.
+ */
+ if (!is_sync && *async_bfqq == NULL) {
+ atomic_inc(&bfqq->ref);
+ bfq_log_bfqq(bfqd, bfqq, "get_queue, bfqq not in async: %p, %d",
+ bfqq, atomic_read(&bfqq->ref));
+ *async_bfqq = bfqq;
+ }
+
+ atomic_inc(&bfqq->ref);
+ bfq_log_bfqq(bfqd, bfqq, "get_queue, at end: %p, %d", bfqq,
+ atomic_read(&bfqq->ref));
+ return bfqq;
+}
+
+static void bfq_update_io_thinktime(struct bfq_data *bfqd,
+ struct cfq_io_context *cic)
+{
+ unsigned long elapsed = jiffies - cic->last_end_request;
+ unsigned long ttime = min(elapsed, 2UL * bfqd->bfq_slice_idle);
+
+ cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
+ cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
+ cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
+}
+
+static void bfq_update_io_seektime(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ struct request *rq)
+{
+ sector_t sdist;
+ u64 total;
+
+ if (bfqq->last_request_pos < blk_rq_pos(rq))
+ sdist = blk_rq_pos(rq) - bfqq->last_request_pos;
+ else
+ sdist = bfqq->last_request_pos - blk_rq_pos(rq);
+
+ /*
+ * Don't allow the seek distance to get too large from the
+ * odd fragment, pagein, etc.
+ */
+ if (bfqq->seek_samples == 0) /* first request, not really a seek */
+ sdist = 0;
+ else if (bfqq->seek_samples <= 60) /* second & third seek */
+ sdist = min(sdist, (bfqq->seek_mean * 4) + 2*1024*1024);
+ else
+ sdist = min(sdist, (bfqq->seek_mean * 4) + 2*1024*64);
+
+ bfqq->seek_samples = (7*bfqq->seek_samples + 256) / 8;
+ bfqq->seek_total = (7*bfqq->seek_total + (u64)256*sdist) / 8;
+ total = bfqq->seek_total + (bfqq->seek_samples/2);
+ do_div(total, bfqq->seek_samples);
+ if (bfq_bfqq_coop(bfqq)) {
+ /*
+ * If the mean seektime increases for a (non-seeky) shared
+ * queue, some cooperator is likely to be idling too much.
+ * On the contrary, if it decreases, some cooperator has
+ * probably waked up.
+ *
+ */
+ if ((sector_t)total < bfqq->seek_mean)
+ bfq_mark_bfqq_some_coop_idle(bfqq) ;
+ else if ((sector_t)total > bfqq->seek_mean)
+ bfq_clear_bfqq_some_coop_idle(bfqq) ;
+ }
+ bfqq->seek_mean = (sector_t)total;
+
+ bfq_log_bfqq(bfqd, bfqq, "dist=%llu mean=%llu", (u64)sdist,
+ (u64)bfqq->seek_mean);
+}
+
+/*
+ * Disable idle window if the process thinks too long or seeks so much that
+ * it doesn't matter.
+ */
+static void bfq_update_idle_window(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ struct cfq_io_context *cic)
+{
+ int enable_idle;
+
+ /* Don't idle for async or idle io prio class. */
+ if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq))
+ return;
+
+ enable_idle = bfq_bfqq_idle_window(bfqq);
+
+ if (atomic_read(&cic->ioc->nr_tasks) == 0 ||
+ bfqd->bfq_slice_idle == 0 ||
+ (bfqd->hw_tag && BFQQ_SEEKY(bfqq) &&
+ bfqq->raising_coeff == 1))
+ enable_idle = 0;
+ else if (bfq_sample_valid(cic->ttime_samples)) {
+ if (cic->ttime_mean > bfqd->bfq_slice_idle &&
+ bfqq->raising_coeff == 1)
+ enable_idle = 0;
+ else
+ enable_idle = 1;
+ }
+ bfq_log_bfqq(bfqd, bfqq, "update_idle_window: enable_idle %d",
+ enable_idle);
+
+ if (enable_idle)
+ bfq_mark_bfqq_idle_window(bfqq);
+ else
+ bfq_clear_bfqq_idle_window(bfqq);
+}
+
+/*
+ * Called when a new fs request (rq) is added to bfqq. Check if there's
+ * something we should do about it.
+ */
+static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ struct request *rq)
+{
+ struct cfq_io_context *cic = RQ_CIC(rq);
+
+ if (rq->cmd_flags & REQ_META)
+ bfqq->meta_pending++;
+
+ bfq_update_io_thinktime(bfqd, cic);
+ bfq_update_io_seektime(bfqd, bfqq, rq);
+ if (bfqq->entity.service > bfq_max_budget(bfqd) / 8 ||
+ !BFQQ_SEEKY(bfqq))
+ bfq_update_idle_window(bfqd, bfqq, cic);
+
+ bfq_log_bfqq(bfqd, bfqq,
+ "rq_enqueued: idle_window=%d (seeky %d, mean %llu)",
+ bfq_bfqq_idle_window(bfqq), BFQQ_SEEKY(bfqq),
+ (long long unsigned)bfqq->seek_mean);
+
+ bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
+
+ if (bfqq == bfqd->active_queue) {
+ /*
+ * If there is just this request queued and the request
+ * is small, just exit.
+ * In this way, if the disk is being idled to wait for a new
+ * request from the active queue, we avoid unplugging the
+ * device now.
+ *
+ * By doing so, we spare the disk to be committed
+ * to serve just a small request. On the contrary, we wait for
+ * the block layer to decide when to unplug the device:
+ * hopefully, new requests will be merged to this
+ * one quickly, then the device will be unplugged
+ * and larger requests will be dispatched.
+ */
+ if (bfqq->queued[rq_is_sync(rq)] == 1 &&
+ blk_rq_sectors(rq) < 32) {
+ return;
+ }
+ if (bfq_bfqq_wait_request(bfqq)) {
+ /*
+ * If we are waiting for a request for this queue, let
+ * it rip immediately and flag that we must not expire
+ * this queue just now.
+ */
+ bfq_clear_bfqq_wait_request(bfqq);
+ del_timer(&bfqd->idle_slice_timer);
+ /*
+ * Here we can safely expire the queue, in
+ * case of budget timeout, without wasting
+ * guarantees
+ */
+ if (bfq_bfqq_budget_timeout(bfqq))
+ bfq_bfqq_expire(bfqd, bfqq, 0,
+ BFQ_BFQQ_BUDGET_TIMEOUT);
+ __blk_run_queue(bfqd->queue);
+ }
+ }
+}
+
+static void bfq_insert_request(struct request_queue *q, struct request *rq)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+
+ assert_spin_locked(bfqd->queue->queue_lock);
+ bfq_init_prio_data(bfqq, RQ_CIC(rq)->ioc);
+
+ bfq_add_rq_rb(rq);
+
+ rq_set_fifo_time(rq, jiffies + bfqd->bfq_fifo_expire[rq_is_sync(rq)]);
+ list_add_tail(&rq->queuelist, &bfqq->fifo);
+
+ bfq_rq_enqueued(bfqd, bfqq, rq);
+}
+
+static void bfq_update_hw_tag(struct bfq_data *bfqd)
+{
+ bfqd->max_rq_in_driver = max(bfqd->max_rq_in_driver,
+ bfqd->rq_in_driver);
+
+ if (bfqd->hw_tag == 1)
+ return;
+
+ /*
+ * This sample is valid if the number of outstanding requests
+ * is large enough to allow a queueing behavior. Note that the
+ * sum is not exact, as it's not taking into account deactivated
+ * requests.
+ */
+ if (bfqd->rq_in_driver + bfqd->queued < BFQ_HW_QUEUE_THRESHOLD)
+ return;
+
+ if (bfqd->hw_tag_samples++ < BFQ_HW_QUEUE_SAMPLES)
+ return;
+
+ bfqd->hw_tag = bfqd->max_rq_in_driver > BFQ_HW_QUEUE_THRESHOLD;
+ bfqd->max_rq_in_driver = 0;
+ bfqd->hw_tag_samples = 0;
+}
+
+static void bfq_completed_request(struct request_queue *q, struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+ struct bfq_data *bfqd = bfqq->bfqd;
+ const int sync = rq_is_sync(rq);
+
+ bfq_log_bfqq(bfqd, bfqq, "completed %u sects req (%d)",
+ blk_rq_sectors(rq), sync);
+
+ bfq_update_hw_tag(bfqd);
+
+ WARN_ON(!bfqd->rq_in_driver);
+ WARN_ON(!bfqq->dispatched);
+ bfqd->rq_in_driver--;
+ bfqq->dispatched--;
+
+ if (bfq_bfqq_sync(bfqq))
+ bfqd->sync_flight--;
+
+ if (sync)
+ RQ_CIC(rq)->last_end_request = jiffies;
+
+ /*
+ * If this is the active queue, check if it needs to be expired,
+ * or if we want to idle in case it has no pending requests.
+ */
+ if (bfqd->active_queue == bfqq) {
+ if (bfq_bfqq_budget_new(bfqq))
+ bfq_set_budget_timeout(bfqd);
+
+ /* Idling is disabled also for cooperation issues:
+ * 1) there is a close cooperator for the queue, or
+ * 2) the queue is shared and some cooperator is likely
+ * to be idle (in this case, by not arming the idle timer,
+ * we try to slow down the queue, to prevent the zones
+ * of the disk accessed by the active cooperators to become
+ * too distant from the zone that will be accessed by the
+ * currently idle cooperators)
+ */
+ if (bfq_may_expire_for_budg_timeout(bfqq))
+ bfq_bfqq_expire(bfqd, bfqq, 0, BFQ_BFQQ_BUDGET_TIMEOUT);
+ else if (sync &&
+ (bfqd->rq_in_driver == 0 ||
+ bfqq->raising_coeff > 1)
+ && RB_EMPTY_ROOT(&bfqq->sort_list)
+ && !bfq_close_cooperator(bfqd, bfqq)
+ && (!bfq_bfqq_coop(bfqq) ||
+ !bfq_bfqq_some_coop_idle(bfqq)))
+ bfq_arm_slice_timer(bfqd);
+ }
+
+ if (!bfqd->rq_in_driver)
+ bfq_schedule_dispatch(bfqd);
+}
+
+/*
+ * We temporarily boost lower priority queues if they are holding fs exclusive
+ * resources. They are boosted to normal prio (CLASS_BE/4).
+ */
+static void bfq_prio_boost(struct bfq_queue *bfqq)
+{
+ if (has_fs_excl()) {
+ /*
+ * Boost idle prio on transactions that would lock out other
+ * users of the filesystem
+ */
+ if (bfq_class_idle(bfqq))
+ bfqq->entity.new_ioprio_class = IOPRIO_CLASS_BE;
+ if (bfqq->entity.new_ioprio > IOPRIO_NORM)
+ bfqq->entity.new_ioprio = IOPRIO_NORM;
+ } else {
+ /*
+ * Unboost the queue (if needed)
+ */
+ bfqq->entity.new_ioprio_class = bfqq->org_ioprio_class;
+ bfqq->entity.new_ioprio = bfqq->org_ioprio;
+ }
+}
+
+static inline int __bfq_may_queue(struct bfq_queue *bfqq)
+{
+ if (bfq_bfqq_wait_request(bfqq) && bfq_bfqq_must_alloc(bfqq)) {
+ bfq_clear_bfqq_must_alloc(bfqq);
+ return ELV_MQUEUE_MUST;
+ }
+
+ return ELV_MQUEUE_MAY;
+}
+
+static int bfq_may_queue(struct request_queue *q, int rw)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct task_struct *tsk = current;
+ struct cfq_io_context *cic;
+ struct bfq_queue *bfqq;
+
+ /*
+ * Don't force setup of a queue from here, as a call to may_queue
+ * does not necessarily imply that a request actually will be queued.
+ * So just lookup a possibly existing queue, or return 'may queue'
+ * if that fails.
+ */
+ cic = bfq_cic_lookup(bfqd, tsk->io_context);
+ if (cic == NULL)
+ return ELV_MQUEUE_MAY;
+
+ bfqq = cic_to_bfqq(cic, rw_is_sync(rw));
+ if (bfqq != NULL) {
+ bfq_init_prio_data(bfqq, cic->ioc);
+ bfq_prio_boost(bfqq);
+
+ return __bfq_may_queue(bfqq);
+ }
+
+ return ELV_MQUEUE_MAY;
+}
+
+/*
+ * Queue lock held here.
+ */
+static void bfq_put_request(struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+
+ if (bfqq != NULL) {
+ const int rw = rq_data_dir(rq);
+
+ BUG_ON(!bfqq->allocated[rw]);
+ bfqq->allocated[rw]--;
+
+ put_io_context(RQ_CIC(rq)->ioc);
+
+ rq->elevator_private[0] = NULL;
+ rq->elevator_private[1] = NULL;
+
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "put_request %p, %d",
+ bfqq, atomic_read(&bfqq->ref));
+ bfq_put_queue(bfqq);
+ }
+}
+
+static struct bfq_queue *
+bfq_merge_bfqqs(struct bfq_data *bfqd, struct cfq_io_context *cic,
+ struct bfq_queue *bfqq)
+{
+ bfq_log_bfqq(bfqd, bfqq, "merging with queue %lu",
+ (long unsigned)bfqq->new_bfqq->pid);
+ cic_set_bfqq(cic, bfqq->new_bfqq, 1);
+ bfq_mark_bfqq_coop(bfqq->new_bfqq);
+ bfq_put_queue(bfqq);
+ return cic_to_bfqq(cic, 1);
+}
+
+/*
+ * Returns NULL if a new bfqq should be allocated, or the old bfqq if this
+ * was the last process referring to said bfqq.
+ */
+static struct bfq_queue *
+bfq_split_bfqq(struct cfq_io_context *cic, struct bfq_queue *bfqq)
+{
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "splitting queue");
+ if (bfqq_process_refs(bfqq) == 1) {
+ bfqq->pid = current->pid;
+ bfq_clear_bfqq_some_coop_idle(bfqq);
+ bfq_clear_bfqq_coop(bfqq);
+ bfq_clear_bfqq_split_coop(bfqq);
+ return bfqq;
+ }
+
+ cic_set_bfqq(cic, NULL, 1);
+
+ bfq_put_cooperator(bfqq);
+
+ bfq_put_queue(bfqq);
+ return NULL;
+}
+
+/*
+ * Allocate bfq data structures associated with this request.
+ */
+static int bfq_set_request(struct request_queue *q, struct request *rq,
+ gfp_t gfp_mask)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct cfq_io_context *cic;
+ const int rw = rq_data_dir(rq);
+ const int is_sync = rq_is_sync(rq);
+ struct bfq_queue *bfqq;
+ struct bfq_group *bfqg;
+ unsigned long flags;
+
+ might_sleep_if(gfp_mask & __GFP_WAIT);
+
+ cic = bfq_get_io_context(bfqd, gfp_mask);
+
+ spin_lock_irqsave(q->queue_lock, flags);
+
+ if (cic == NULL)
+ goto queue_fail;
+
+ bfqg = bfq_cic_update_cgroup(cic);
+
+new_queue:
+ bfqq = cic_to_bfqq(cic, is_sync);
+ if (bfqq == NULL || bfqq == &bfqd->oom_bfqq) {
+ bfqq = bfq_get_queue(bfqd, bfqg, is_sync, cic->ioc, gfp_mask);
+ cic_set_bfqq(cic, bfqq, is_sync);
+ } else {
+ /*
+ * If the queue was seeky for too long, break it apart.
+ */
+ if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) {
+ bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq");
+ bfqq = bfq_split_bfqq(cic, bfqq);
+ if (!bfqq)
+ goto new_queue;
+ }
+
+ /*
+ * Check to see if this queue is scheduled to merge with
+ * another closely cooperating queue. The merging of queues
+ * happens here as it must be done in process context.
+ * The reference on new_bfqq was taken in merge_bfqqs.
+ */
+ if (bfqq->new_bfqq != NULL)
+ bfqq = bfq_merge_bfqqs(bfqd, cic, bfqq);
+ }
+
+ bfqq->allocated[rw]++;
+ atomic_inc(&bfqq->ref);
+ bfq_log_bfqq(bfqd, bfqq, "set_request: bfqq %p, %d", bfqq,
+ atomic_read(&bfqq->ref));
+
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ rq->elevator_private[0] = cic;
+ rq->elevator_private[1] = bfqq;
+
+ return 0;
+
+queue_fail:
+ if (cic != NULL)
+ put_io_context(cic->ioc);
+
+ bfq_schedule_dispatch(bfqd);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ return 1;
+}
+
+static void bfq_kick_queue(struct work_struct *work)
+{
+ struct bfq_data *bfqd =
+ container_of(work, struct bfq_data, unplug_work);
+ struct request_queue *q = bfqd->queue;
+
+ spin_lock_irq(q->queue_lock);
+ __blk_run_queue(q);
+ spin_unlock_irq(q->queue_lock);
+}
+
+/*
+ * Handler of the expiration of the timer running if the active_queue
+ * is idling inside its time slice.
+ */
+static void bfq_idle_slice_timer(unsigned long data)
+{
+ struct bfq_data *bfqd = (struct bfq_data *)data;
+ struct bfq_queue *bfqq;
+ unsigned long flags;
+ enum bfqq_expiration reason;
+
+ spin_lock_irqsave(bfqd->queue->queue_lock, flags);
+
+ bfqq = bfqd->active_queue;
+ /*
+ * Theoretical race here: active_queue can be NULL or different
+ * from the queue that was idling if the timer handler spins on
+ * the queue_lock and a new request arrives for the current
+ * queue and there is a full dispatch cycle that changes the
+ * active_queue. This can hardly happen, but in the worst case
+ * we just expire a queue too early.
+ */
+ if (bfqq != NULL) {
+ bfq_log_bfqq(bfqd, bfqq, "slice_timer expired");
+ if (bfq_bfqq_budget_timeout(bfqq))
+ /*
+ * Also here the queue can be safely expired
+ * for budget timeout without wasting
+ * guarantees
+ */
+ reason = BFQ_BFQQ_BUDGET_TIMEOUT;
+ else if (bfqq->queued[0] == 0 && bfqq->queued[1] == 0)
+ /*
+ * The queue may not be empty upon timer expiration,
+ * because we may not disable the timer when the first
+ * request of the active queue arrives during
+ * disk idling
+ */
+ reason = BFQ_BFQQ_TOO_IDLE;
+ else
+ goto schedule_dispatch;
+
+ bfq_bfqq_expire(bfqd, bfqq, 1, reason);
+ }
+
+schedule_dispatch:
+ bfq_schedule_dispatch(bfqd);
+
+ spin_unlock_irqrestore(bfqd->queue->queue_lock, flags);
+}
+
+static void bfq_shutdown_timer_wq(struct bfq_data *bfqd)
+{
+ del_timer_sync(&bfqd->idle_slice_timer);
+ cancel_work_sync(&bfqd->unplug_work);
+}
+
+static inline void __bfq_put_async_bfqq(struct bfq_data *bfqd,
+ struct bfq_queue **bfqq_ptr)
+{
+ struct bfq_group *root_group = bfqd->root_group;
+ struct bfq_queue *bfqq = *bfqq_ptr;
+
+ bfq_log(bfqd, "put_async_bfqq: %p", bfqq);
+ if (bfqq != NULL) {
+ bfq_bfqq_move(bfqd, bfqq, &bfqq->entity, root_group);
+ bfq_log_bfqq(bfqd, bfqq, "put_async_bfqq: putting %p, %d",
+ bfqq, atomic_read(&bfqq->ref));
+ bfq_put_queue(bfqq);
+ *bfqq_ptr = NULL;
+ }
+}
+
+/*
+ * Release all the bfqg references to its async queues. If we are
+ * deallocating the group these queues may still contain requests, so
+ * we reparent them to the root cgroup (i.e., the only one that will
+ * exist for sure untill all the requests on a device are gone).
+ */
+static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg)
+{
+ int i, j;
+
+ for (i = 0; i < 2; i++)
+ for (j = 0; j < IOPRIO_BE_NR; j++)
+ __bfq_put_async_bfqq(bfqd, &bfqg->async_bfqq[i][j]);
+
+ __bfq_put_async_bfqq(bfqd, &bfqg->async_idle_bfqq);
+}
+
+static void bfq_exit_queue(struct elevator_queue *e)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ struct request_queue *q = bfqd->queue;
+ struct bfq_queue *bfqq, *n;
+ struct cfq_io_context *cic;
+
+ bfq_shutdown_timer_wq(bfqd);
+
+ spin_lock_irq(q->queue_lock);
+
+ while (!list_empty(&bfqd->cic_list)) {
+ cic = list_entry(bfqd->cic_list.next, struct cfq_io_context,
+ queue_list);
+ __bfq_exit_single_io_context(bfqd, cic);
+ }
+
+ BUG_ON(bfqd->active_queue != NULL);
+ list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list)
+ bfq_deactivate_bfqq(bfqd, bfqq, 0);
+
+ bfq_disconnect_groups(bfqd);
+ spin_unlock_irq(q->queue_lock);
+
+ bfq_shutdown_timer_wq(bfqd);
+
+ spin_lock(&cic_index_lock);
+ ida_remove(&cic_index_ida, bfqd->cic_index);
+ spin_unlock(&cic_index_lock);
+
+ /* Wait for cic->key accessors to exit their grace periods. */
+ synchronize_rcu();
+
+ BUG_ON(timer_pending(&bfqd->idle_slice_timer));
+
+ bfq_free_root_group(bfqd);
+ kfree(bfqd);
+}
+
+static int bfq_alloc_cic_index(void)
+{
+ int index, error;
+
+ do {
+ if (!ida_pre_get(&cic_index_ida, GFP_KERNEL))
+ return -ENOMEM;
+
+ spin_lock(&cic_index_lock);
+ error = ida_get_new(&cic_index_ida, &index);
+ spin_unlock(&cic_index_lock);
+ if (error && error != -EAGAIN)
+ return error;
+ } while (error);
+
+ return index;
+}
+
+static void *bfq_init_queue(struct request_queue *q)
+{
+ struct bfq_group *bfqg;
+ struct bfq_data *bfqd;
+ int i;
+
+ i = bfq_alloc_cic_index();
+ if (i < 0)
+ return NULL;
+
+ bfqd = kmalloc_node(sizeof(*bfqd), GFP_KERNEL | __GFP_ZERO, q->node);
+ if (bfqd == NULL)
+ return NULL;
+
+ bfqd->cic_index = i;
+
+ /*
+ * Our fallback bfqq if bfq_find_alloc_queue() runs into OOM issues.
+ * Grab a permanent reference to it, so that the normal code flow
+ * will not attempt to free it.
+ */
+ bfq_init_bfqq(bfqd, &bfqd->oom_bfqq, 1, 0);
+ atomic_inc(&bfqd->oom_bfqq.ref);
+
+ INIT_LIST_HEAD(&bfqd->cic_list);
+
+ bfqd->queue = q;
+
+ bfqg = bfq_alloc_root_group(bfqd, q->node);
+ if (bfqg == NULL) {
+ kfree(bfqd);
+ return NULL;
+ }
+
+ bfqd->root_group = bfqg;
+
+ init_timer(&bfqd->idle_slice_timer);
+ bfqd->idle_slice_timer.function = bfq_idle_slice_timer;
+ bfqd->idle_slice_timer.data = (unsigned long)bfqd;
+
+ bfqd->rq_pos_tree = RB_ROOT;
+
+ INIT_WORK(&bfqd->unplug_work, bfq_kick_queue);
+
+ INIT_LIST_HEAD(&bfqd->active_list);
+ INIT_LIST_HEAD(&bfqd->idle_list);
+
+ bfqd->hw_tag = -1;
+
+ bfqd->bfq_max_budget = bfq_default_max_budget;
+
+ bfqd->bfq_quantum = bfq_quantum;
+ bfqd->bfq_fifo_expire[0] = bfq_fifo_expire[0];
+ bfqd->bfq_fifo_expire[1] = bfq_fifo_expire[1];
+ bfqd->bfq_back_max = bfq_back_max;
+ bfqd->bfq_back_penalty = bfq_back_penalty;
+ bfqd->bfq_slice_idle = bfq_slice_idle;
+ bfqd->bfq_class_idle_last_service = 0;
+ bfqd->bfq_max_budget_async_rq = bfq_max_budget_async_rq;
+ bfqd->bfq_timeout[BLK_RW_ASYNC] = bfq_timeout_async;
+ bfqd->bfq_timeout[BLK_RW_SYNC] = bfq_timeout_sync;
+
+ bfqd->low_latency = true;
+
+ bfqd->bfq_raising_coeff = 20;
+ bfqd->bfq_raising_rt_max_time = msecs_to_jiffies(300);
+ bfqd->bfq_raising_max_time = 0;
+ bfqd->bfq_raising_min_idle_time = msecs_to_jiffies(2000);
+ bfqd->bfq_raising_min_inter_arr_async = msecs_to_jiffies(500);
+ bfqd->bfq_raising_max_softrt_rate = 7000;
+
+ /* Initially estimate the device's peak rate as the reference rate */
+ if (blk_queue_nonrot(bfqd->queue)) {
+ bfqd->RT_prod = R_nonrot * T_nonrot;
+ bfqd->peak_rate = R_nonrot;
+ } else {
+ bfqd->RT_prod = R_rot * T_rot;
+ bfqd->peak_rate = R_rot;
+ }
+
+ return bfqd;
+}
+
+static void bfq_slab_kill(void)
+{
+ if (bfq_pool != NULL)
+ kmem_cache_destroy(bfq_pool);
+ if (bfq_ioc_pool != NULL)
+ kmem_cache_destroy(bfq_ioc_pool);
+}
+
+static int __init bfq_slab_setup(void)
+{
+ bfq_pool = KMEM_CACHE(bfq_queue, 0);
+ if (bfq_pool == NULL)
+ goto fail;
+
+ bfq_ioc_pool = kmem_cache_create("bfq_io_context",
+ sizeof(struct cfq_io_context),
+ __alignof__(struct cfq_io_context),
+ 0, NULL);
+ if (bfq_ioc_pool == NULL)
+ goto fail;
+
+ return 0;
+fail:
+ bfq_slab_kill();
+ return -ENOMEM;
+}
+
+static ssize_t bfq_var_show(unsigned int var, char *page)
+{
+ return sprintf(page, "%d\n", var);
+}
+
+static ssize_t bfq_var_store(unsigned long *var, const char *page, size_t count)
+{
+ unsigned long new_val;
+ int ret = strict_strtoul(page, 10, &new_val);
+
+ if (ret == 0)
+ *var = new_val;
+
+ return count;
+}
+
+static ssize_t bfq_raising_max_time_show(struct elevator_queue *e, char *page)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ return sprintf(page, "%d\n", bfqd->bfq_raising_max_time > 0 ?
+ bfqd->bfq_raising_max_time :
+ bfq_wrais_duration(bfqd));
+}
+
+static ssize_t bfq_weights_show(struct elevator_queue *e, char *page)
+{
+ struct bfq_queue *bfqq;
+ struct bfq_data *bfqd = e->elevator_data;
+ ssize_t num_char = 0;
+
+ spin_lock_irq(bfqd->queue->queue_lock);
+
+ num_char += sprintf(page + num_char, "Active:\n");
+ list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) {
+ num_char += sprintf(page + num_char,
+ "pid%d: weight %hu, dur %d/%u\n",
+ bfqq->pid,
+ bfqq->entity.weight,
+ jiffies_to_msecs(jiffies -
+ bfqq->last_rais_start_finish),
+ jiffies_to_msecs(bfqq->raising_cur_max_time));
+ }
+ num_char += sprintf(page + num_char, "Idle:\n");
+ list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list) {
+ num_char += sprintf(page + num_char,
+ "pid%d: weight %hu, dur %d/%u\n",
+ bfqq->pid,
+ bfqq->entity.weight,
+ jiffies_to_msecs(jiffies -
+ bfqq->last_rais_start_finish),
+ jiffies_to_msecs(bfqq->raising_cur_max_time));
+ }
+
+ spin_unlock_irq(bfqd->queue->queue_lock);
+
+ return num_char;
+}
+
+#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
+static ssize_t __FUNC(struct elevator_queue *e, char *page) \
+{ \
+ struct bfq_data *bfqd = e->elevator_data; \
+ unsigned int __data = __VAR; \
+ if (__CONV) \
+ __data = jiffies_to_msecs(__data); \
+ return bfq_var_show(__data, (page)); \
+}
+SHOW_FUNCTION(bfq_quantum_show, bfqd->bfq_quantum, 0);
+SHOW_FUNCTION(bfq_fifo_expire_sync_show, bfqd->bfq_fifo_expire[1], 1);
+SHOW_FUNCTION(bfq_fifo_expire_async_show, bfqd->bfq_fifo_expire[0], 1);
+SHOW_FUNCTION(bfq_back_seek_max_show, bfqd->bfq_back_max, 0);
+SHOW_FUNCTION(bfq_back_seek_penalty_show, bfqd->bfq_back_penalty, 0);
+SHOW_FUNCTION(bfq_slice_idle_show, bfqd->bfq_slice_idle, 1);
+SHOW_FUNCTION(bfq_max_budget_show, bfqd->bfq_user_max_budget, 0);
+SHOW_FUNCTION(bfq_max_budget_async_rq_show, bfqd->bfq_max_budget_async_rq, 0);
+SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout[BLK_RW_SYNC], 1);
+SHOW_FUNCTION(bfq_timeout_async_show, bfqd->bfq_timeout[BLK_RW_ASYNC], 1);
+SHOW_FUNCTION(bfq_low_latency_show, bfqd->low_latency, 0);
+SHOW_FUNCTION(bfq_raising_coeff_show, bfqd->bfq_raising_coeff, 0);
+SHOW_FUNCTION(bfq_raising_rt_max_time_show, bfqd->bfq_raising_rt_max_time, 1);
+SHOW_FUNCTION(bfq_raising_min_idle_time_show, bfqd->bfq_raising_min_idle_time,
+ 1);
+SHOW_FUNCTION(bfq_raising_min_inter_arr_async_show,
+ bfqd->bfq_raising_min_inter_arr_async,
+ 1);
+SHOW_FUNCTION(bfq_raising_max_softrt_rate_show,
+ bfqd->bfq_raising_max_softrt_rate, 0);
+#undef SHOW_FUNCTION
+
+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
+static ssize_t \
+__FUNC(struct elevator_queue *e, const char *page, size_t count) \
+{ \
+ struct bfq_data *bfqd = e->elevator_data; \
+ unsigned long __data; \
+ int ret = bfq_var_store(&__data, (page), count); \
+ if (__data < (MIN)) \
+ __data = (MIN); \
+ else if (__data > (MAX)) \
+ __data = (MAX); \
+ if (__CONV) \
+ *(__PTR) = msecs_to_jiffies(__data); \
+ else \
+ *(__PTR) = __data; \
+ return ret; \
+}
+STORE_FUNCTION(bfq_quantum_store, &bfqd->bfq_quantum, 1, INT_MAX, 0);
+STORE_FUNCTION(bfq_fifo_expire_sync_store, &bfqd->bfq_fifo_expire[1], 1,
+ INT_MAX, 1);
+STORE_FUNCTION(bfq_fifo_expire_async_store, &bfqd->bfq_fifo_expire[0], 1,
+ INT_MAX, 1);
+STORE_FUNCTION(bfq_back_seek_max_store, &bfqd->bfq_back_max, 0, INT_MAX, 0);
+STORE_FUNCTION(bfq_back_seek_penalty_store, &bfqd->bfq_back_penalty, 1,
+ INT_MAX, 0);
+STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 1);
+STORE_FUNCTION(bfq_max_budget_async_rq_store, &bfqd->bfq_max_budget_async_rq,
+ 1, INT_MAX, 0);
+STORE_FUNCTION(bfq_timeout_async_store, &bfqd->bfq_timeout[BLK_RW_ASYNC], 0,
+ INT_MAX, 1);
+STORE_FUNCTION(bfq_raising_coeff_store, &bfqd->bfq_raising_coeff, 1,
+ INT_MAX, 0);
+STORE_FUNCTION(bfq_raising_max_time_store, &bfqd->bfq_raising_max_time, 0,
+ INT_MAX, 1);
+STORE_FUNCTION(bfq_raising_rt_max_time_store, &bfqd->bfq_raising_rt_max_time, 0,
+ INT_MAX, 1);
+STORE_FUNCTION(bfq_raising_min_idle_time_store,
+ &bfqd->bfq_raising_min_idle_time, 0, INT_MAX, 1);
+STORE_FUNCTION(bfq_raising_min_inter_arr_async_store,
+ &bfqd->bfq_raising_min_inter_arr_async, 0, INT_MAX, 1);
+STORE_FUNCTION(bfq_raising_max_softrt_rate_store,
+ &bfqd->bfq_raising_max_softrt_rate, 0, INT_MAX, 0);
+#undef STORE_FUNCTION
+
+/* do nothing for the moment */
+static ssize_t bfq_weights_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ return count;
+}
+
+static inline unsigned long bfq_estimated_max_budget(struct bfq_data *bfqd)
+{
+ u64 timeout = jiffies_to_msecs(bfqd->bfq_timeout[BLK_RW_SYNC]);
+
+ if (bfqd->peak_rate_samples >= BFQ_PEAK_RATE_SAMPLES)
+ return bfq_calc_max_budget(bfqd->peak_rate, timeout);
+ else
+ return bfq_default_max_budget;
+}
+
+static ssize_t bfq_max_budget_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ unsigned long __data;
+ int ret = bfq_var_store(&__data, (page), count);
+
+ if (__data == 0)
+ bfqd->bfq_max_budget = bfq_estimated_max_budget(bfqd);
+ else {
+ if (__data > INT_MAX)
+ __data = INT_MAX;
+ bfqd->bfq_max_budget = __data;
+ }
+
+ bfqd->bfq_user_max_budget = __data;
+
+ return ret;
+}
+
+static ssize_t bfq_timeout_sync_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ unsigned long __data;
+ int ret = bfq_var_store(&__data, (page), count);
+
+ if (__data < 1)
+ __data = 1;
+ else if (__data > INT_MAX)
+ __data = INT_MAX;
+
+ bfqd->bfq_timeout[BLK_RW_SYNC] = msecs_to_jiffies(__data);
+ if (bfqd->bfq_user_max_budget == 0)
+ bfqd->bfq_max_budget = bfq_estimated_max_budget(bfqd);
+
+ return ret;
+}
+
+static ssize_t bfq_low_latency_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ unsigned long __data;
+ int ret = bfq_var_store(&__data, (page), count);
+
+ if (__data > 1)
+ __data = 1;
+ bfqd->low_latency = __data;
+
+ return ret;
+}
+
+#define BFQ_ATTR(name) \
+ __ATTR(name, S_IRUGO|S_IWUSR, bfq_##name##_show, bfq_##name##_store)
+
+static struct elv_fs_entry bfq_attrs[] = {
+ BFQ_ATTR(quantum),
+ BFQ_ATTR(fifo_expire_sync),
+ BFQ_ATTR(fifo_expire_async),
+ BFQ_ATTR(back_seek_max),
+ BFQ_ATTR(back_seek_penalty),
+ BFQ_ATTR(slice_idle),
+ BFQ_ATTR(max_budget),
+ BFQ_ATTR(max_budget_async_rq),
+ BFQ_ATTR(timeout_sync),
+ BFQ_ATTR(timeout_async),
+ BFQ_ATTR(low_latency),
+ BFQ_ATTR(raising_coeff),
+ BFQ_ATTR(raising_max_time),
+ BFQ_ATTR(raising_rt_max_time),
+ BFQ_ATTR(raising_min_idle_time),
+ BFQ_ATTR(raising_min_inter_arr_async),
+ BFQ_ATTR(raising_max_softrt_rate),
+ BFQ_ATTR(weights),
+ __ATTR_NULL
+};
+
+static struct elevator_type iosched_bfq = {
+ .ops = {
+ .elevator_merge_fn = bfq_merge,
+ .elevator_merged_fn = bfq_merged_request,
+ .elevator_merge_req_fn = bfq_merged_requests,
+ .elevator_allow_merge_fn = bfq_allow_merge,
+ .elevator_dispatch_fn = bfq_dispatch_requests,
+ .elevator_add_req_fn = bfq_insert_request,
+ .elevator_activate_req_fn = bfq_activate_request,
+ .elevator_deactivate_req_fn = bfq_deactivate_request,
+ .elevator_completed_req_fn = bfq_completed_request,
+ .elevator_former_req_fn = elv_rb_former_request,
+ .elevator_latter_req_fn = elv_rb_latter_request,
+ .elevator_set_req_fn = bfq_set_request,
+ .elevator_put_req_fn = bfq_put_request,
+ .elevator_may_queue_fn = bfq_may_queue,
+ .elevator_init_fn = bfq_init_queue,
+ .elevator_exit_fn = bfq_exit_queue,
+ .trim = bfq_free_io_context,
+ },
+ .elevator_attrs = bfq_attrs,
+ .elevator_name = "bfq",
+ .elevator_owner = THIS_MODULE,
+};
+
+static int __init bfq_init(void)
+{
+ /*
+ * Can be 0 on HZ < 1000 setups.
+ */
+ if (bfq_slice_idle == 0)
+ bfq_slice_idle = 1;
+
+ if (bfq_timeout_async == 0)
+ bfq_timeout_async = 1;
+
+ if (bfq_slab_setup())
+ return -ENOMEM;
+
+ elv_register(&iosched_bfq);
+
+ return 0;
+}
+
+static void __exit bfq_exit(void)
+{
+ DECLARE_COMPLETION_ONSTACK(all_gone);
+ elv_unregister(&iosched_bfq);
+ bfq_ioc_gone = &all_gone;
+ /* bfq_ioc_gone's update must be visible before reading bfq_ioc_count */
+ smp_wmb();
+ if (elv_ioc_count_read(bfq_ioc_count) != 0)
+ wait_for_completion(&all_gone);
+ ida_destroy(&cic_index_ida);
+ bfq_slab_kill();
+}
+
+module_init(bfq_init);
+module_exit(bfq_exit);
+
+MODULE_AUTHOR("Fabio Checconi, Paolo Valente");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Budget Fair Queueing IO scheduler");
--- /dev/null
+++ b/block/bfq-sched.c
@@ -0,0 +1,1068 @@
+/*
+ * BFQ: Hierarchical B-WF2Q+ scheduler.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
+ */
+
+#ifdef CONFIG_CGROUP_BFQIO
+#define for_each_entity(entity) \
+ for (; entity != NULL; entity = entity->parent)
+
+#define for_each_entity_safe(entity, parent) \
+ for (; entity && ({ parent = entity->parent; 1; }); entity = parent)
+
+static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
+ int extract,
+ struct bfq_data *bfqd);
+
+static inline void bfq_update_budget(struct bfq_entity *next_active)
+{
+ struct bfq_entity *bfqg_entity;
+ struct bfq_group *bfqg;
+ struct bfq_sched_data *group_sd;
+
+ BUG_ON(next_active == NULL);
+
+ group_sd = next_active->sched_data;
+
+ bfqg = container_of(group_sd, struct bfq_group, sched_data);
+ /*
+ * bfq_group's my_entity field is not NULL only if the group
+ * is not the root group. We must not touch the root entity
+ * as it must never become an active entity.
+ */
+ bfqg_entity = bfqg->my_entity;
+ if (bfqg_entity != NULL)
+ bfqg_entity->budget = next_active->budget;
+}
+
+static int bfq_update_next_active(struct bfq_sched_data *sd)
+{
+ struct bfq_entity *next_active;
+
+ if (sd->active_entity != NULL)
+ /* will update/requeue at the end of service */
+ return 0;
+
+ /*
+ * NOTE: this can be improved in many ways, such as returning
+ * 1 (and thus propagating upwards the update) only when the
+ * budget changes, or caching the bfqq that will be scheduled
+ * next from this subtree. By now we worry more about
+ * correctness than about performance...
+ */
+ next_active = bfq_lookup_next_entity(sd, 0, NULL);
+ sd->next_active = next_active;
+
+ if (next_active != NULL)
+ bfq_update_budget(next_active);
+
+ return 1;
+}
+
+static inline void bfq_check_next_active(struct bfq_sched_data *sd,
+ struct bfq_entity *entity)
+{
+ BUG_ON(sd->next_active != entity);
+}
+#else
+#define for_each_entity(entity) \
+ for (; entity != NULL; entity = NULL)
+
+#define for_each_entity_safe(entity, parent) \
+ for (parent = NULL; entity != NULL; entity = parent)
+
+static inline int bfq_update_next_active(struct bfq_sched_data *sd)
+{
+ return 0;
+}
+
+static inline void bfq_check_next_active(struct bfq_sched_data *sd,
+ struct bfq_entity *entity)
+{
+}
+
+static inline void bfq_update_budget(struct bfq_entity *next_active)
+{
+}
+#endif
+
+/*
+ * Shift for timestamp calculations. This actually limits the maximum
+ * service allowed in one timestamp delta (small shift values increase it),
+ * the maximum total weight that can be used for the queues in the system
+ * (big shift values increase it), and the period of virtual time wraparounds.
+ */
+#define WFQ_SERVICE_SHIFT 22
+
+/**
+ * bfq_gt - compare two timestamps.
+ * @a: first ts.
+ * @b: second ts.
+ *
+ * Return @a > @b, dealing with wrapping correctly.
+ */
+static inline int bfq_gt(u64 a, u64 b)
+{
+ return (s64)(a - b) > 0;
+}
+
+static inline struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = NULL;
+
+ BUG_ON(entity == NULL);
+
+ if (entity->my_sched_data == NULL)
+ bfqq = container_of(entity, struct bfq_queue, entity);
+
+ return bfqq;
+}
+
+
+/**
+ * bfq_delta - map service into the virtual time domain.
+ * @service: amount of service.
+ * @weight: scale factor (weight of an entity or weight sum).
+ */
+static inline u64 bfq_delta(unsigned long service,
+ unsigned long weight)
+{
+ u64 d = (u64)service << WFQ_SERVICE_SHIFT;
+
+ do_div(d, weight);
+ return d;
+}
+
+/**
+ * bfq_calc_finish - assign the finish time to an entity.
+ * @entity: the entity to act upon.
+ * @service: the service to be charged to the entity.
+ */
+static inline void bfq_calc_finish(struct bfq_entity *entity,
+ unsigned long service)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ BUG_ON(entity->weight == 0);
+
+ entity->finish = entity->start +
+ bfq_delta(service, entity->weight);
+
+ if (bfqq != NULL) {
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "calc_finish: serv %lu, w %d",
+ service, entity->weight);
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "calc_finish: start %llu, finish %llu, delta %llu",
+ entity->start, entity->finish,
+ bfq_delta(service, entity->weight));
+ }
+}
+
+/**
+ * bfq_entity_of - get an entity from a node.
+ * @node: the node field of the entity.
+ *
+ * Convert a node pointer to the relative entity. This is used only
+ * to simplify the logic of some functions and not as the generic
+ * conversion mechanism because, e.g., in the tree walking functions,
+ * the check for a %NULL value would be redundant.
+ */
+static inline struct bfq_entity *bfq_entity_of(struct rb_node *node)
+{
+ struct bfq_entity *entity = NULL;
+
+ if (node != NULL)
+ entity = rb_entry(node, struct bfq_entity, rb_node);
+
+ return entity;
+}
+
+/**
+ * bfq_extract - remove an entity from a tree.
+ * @root: the tree root.
+ * @entity: the entity to remove.
+ */
+static inline void bfq_extract(struct rb_root *root,
+ struct bfq_entity *entity)
+{
+ BUG_ON(entity->tree != root);
+
+ entity->tree = NULL;
+ rb_erase(&entity->rb_node, root);
+}
+
+/**
+ * bfq_idle_extract - extract an entity from the idle tree.
+ * @st: the service tree of the owning @entity.
+ * @entity: the entity being removed.
+ */
+static void bfq_idle_extract(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct rb_node *next;
+
+ BUG_ON(entity->tree != &st->idle);
+
+ if (entity == st->first_idle) {
+ next = rb_next(&entity->rb_node);
+ st->first_idle = bfq_entity_of(next);
+ }
+
+ if (entity == st->last_idle) {
+ next = rb_prev(&entity->rb_node);
+ st->last_idle = bfq_entity_of(next);
+ }
+
+ bfq_extract(&st->idle, entity);
+
+ if (bfqq != NULL)
+ list_del(&bfqq->bfqq_list);
+}
+
+/**
+ * bfq_insert - generic tree insertion.
+ * @root: tree root.
+ * @entity: entity to insert.
+ *
+ * This is used for the idle and the active tree, since they are both
+ * ordered by finish time.
+ */
+static void bfq_insert(struct rb_root *root, struct bfq_entity *entity)
+{
+ struct bfq_entity *entry;
+ struct rb_node **node = &root->rb_node;
+ struct rb_node *parent = NULL;
+
+ BUG_ON(entity->tree != NULL);
+
+ while (*node != NULL) {
+ parent = *node;
+ entry = rb_entry(parent, struct bfq_entity, rb_node);
+
+ if (bfq_gt(entry->finish, entity->finish))
+ node = &parent->rb_left;
+ else
+ node = &parent->rb_right;
+ }
+
+ rb_link_node(&entity->rb_node, parent, node);
+ rb_insert_color(&entity->rb_node, root);
+
+ entity->tree = root;
+}
+
+/**
+ * bfq_update_min - update the min_start field of a entity.
+ * @entity: the entity to update.
+ * @node: one of its children.
+ *
+ * This function is called when @entity may store an invalid value for
+ * min_start due to updates to the active tree. The function assumes
+ * that the subtree rooted at @node (which may be its left or its right
+ * child) has a valid min_start value.
+ */
+static inline void bfq_update_min(struct bfq_entity *entity,
+ struct rb_node *node)
+{
+ struct bfq_entity *child;
+
+ if (node != NULL) {
+ child = rb_entry(node, struct bfq_entity, rb_node);
+ if (bfq_gt(entity->min_start, child->min_start))
+ entity->min_start = child->min_start;
+ }
+}
+
+/**
+ * bfq_update_active_node - recalculate min_start.
+ * @node: the node to update.
+ *
+ * @node may have changed position or one of its children may have moved,
+ * this function updates its min_start value. The left and right subtrees
+ * are assumed to hold a correct min_start value.
+ */
+static inline void bfq_update_active_node(struct rb_node *node)
+{
+ struct bfq_entity *entity = rb_entry(node, struct bfq_entity, rb_node);
+
+ entity->min_start = entity->start;
+ bfq_update_min(entity, node->rb_right);
+ bfq_update_min(entity, node->rb_left);
+}
+
+/**
+ * bfq_update_active_tree - update min_start for the whole active tree.
+ * @node: the starting node.
+ *
+ * @node must be the deepest modified node after an update. This function
+ * updates its min_start using the values held by its children, assuming
+ * that they did not change, and then updates all the nodes that may have
+ * changed in the path to the root. The only nodes that may have changed
+ * are the ones in the path or their siblings.
+ */
+static void bfq_update_active_tree(struct rb_node *node)
+{
+ struct rb_node *parent;
+
+up:
+ bfq_update_active_node(node);
+
+ parent = rb_parent(node);
+ if (parent == NULL)
+ return;
+
+ if (node == parent->rb_left && parent->rb_right != NULL)
+ bfq_update_active_node(parent->rb_right);
+ else if (parent->rb_left != NULL)
+ bfq_update_active_node(parent->rb_left);
+
+ node = parent;
+ goto up;
+}
+
+/**
+ * bfq_active_insert - insert an entity in the active tree of its group/device.
+ * @st: the service tree of the entity.
+ * @entity: the entity being inserted.
+ *
+ * The active tree is ordered by finish time, but an extra key is kept
+ * per each node, containing the minimum value for the start times of
+ * its children (and the node itself), so it's possible to search for
+ * the eligible node with the lowest finish time in logarithmic time.
+ */
+static void bfq_active_insert(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct rb_node *node = &entity->rb_node;
+
+ bfq_insert(&st->active, entity);
+
+ if (node->rb_left != NULL)
+ node = node->rb_left;
+ else if (node->rb_right != NULL)
+ node = node->rb_right;
+
+ bfq_update_active_tree(node);
+
+ if (bfqq != NULL)
+ list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list);
+}
+
+/**
+ * bfq_ioprio_to_weight - calc a weight from an ioprio.
+ * @ioprio: the ioprio value to convert.
+ */
+static unsigned short bfq_ioprio_to_weight(int ioprio)
+{
+ WARN_ON(ioprio < 0 || ioprio >= IOPRIO_BE_NR);
+ return IOPRIO_BE_NR - ioprio;
+}
+
+/**
+ * bfq_weight_to_ioprio - calc an ioprio from a weight.
+ * @weight: the weight value to convert.
+ *
+ * To preserve as mush as possible the old only-ioprio user interface,
+ * 0 is used as an escape ioprio value for weights (numerically) equal or
+ * larger than IOPRIO_BE_NR
+ */
+static unsigned short bfq_weight_to_ioprio(int weight)
+{
+ WARN_ON(weight < BFQ_MIN_WEIGHT || weight > BFQ_MAX_WEIGHT);
+ return IOPRIO_BE_NR - weight < 0 ? 0 : IOPRIO_BE_NR - weight;
+}
+
+static inline void bfq_get_entity(struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ if (bfqq != NULL) {
+ atomic_inc(&bfqq->ref);
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d",
+ bfqq, atomic_read(&bfqq->ref));
+ }
+}
+
+/**
+ * bfq_find_deepest - find the deepest node that an extraction can modify.
+ * @node: the node being removed.
+ *
+ * Do the first step of an extraction in an rb tree, looking for the
+ * node that will replace @node, and returning the deepest node that
+ * the following modifications to the tree can touch. If @node is the
+ * last node in the tree return %NULL.
+ */
+static struct rb_node *bfq_find_deepest(struct rb_node *node)
+{
+ struct rb_node *deepest;
+
+ if (node->rb_right == NULL && node->rb_left == NULL)
+ deepest = rb_parent(node);
+ else if (node->rb_right == NULL)
+ deepest = node->rb_left;
+ else if (node->rb_left == NULL)
+ deepest = node->rb_right;
+ else {
+ deepest = rb_next(node);
+ if (deepest->rb_right != NULL)
+ deepest = deepest->rb_right;
+ else if (rb_parent(deepest) != node)
+ deepest = rb_parent(deepest);
+ }
+
+ return deepest;
+}
+
+/**
+ * bfq_active_extract - remove an entity from the active tree.
+ * @st: the service_tree containing the tree.
+ * @entity: the entity being removed.
+ */
+static void bfq_active_extract(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct rb_node *node;
+
+ node = bfq_find_deepest(&entity->rb_node);
+ bfq_extract(&st->active, entity);
+
+ if (node != NULL)
+ bfq_update_active_tree(node);
+
+ if (bfqq != NULL)
+ list_del(&bfqq->bfqq_list);
+}
+
+/**
+ * bfq_idle_insert - insert an entity into the idle tree.
+ * @st: the service tree containing the tree.
+ * @entity: the entity to insert.
+ */
+static void bfq_idle_insert(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct bfq_entity *first_idle = st->first_idle;
+ struct bfq_entity *last_idle = st->last_idle;
+
+ if (first_idle == NULL || bfq_gt(first_idle->finish, entity->finish))
+ st->first_idle = entity;
+ if (last_idle == NULL || bfq_gt(entity->finish, last_idle->finish))
+ st->last_idle = entity;
+
+ bfq_insert(&st->idle, entity);
+
+ if (bfqq != NULL)
+ list_add(&bfqq->bfqq_list, &bfqq->bfqd->idle_list);
+}
+
+/**
+ * bfq_forget_entity - remove an entity from the wfq trees.
+ * @st: the service tree.
+ * @entity: the entity being removed.
+ *
+ * Update the device status and forget everything about @entity, putting
+ * the device reference to it, if it is a queue. Entities belonging to
+ * groups are not refcounted.
+ */
+static void bfq_forget_entity(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ BUG_ON(!entity->on_st);
+
+ entity->on_st = 0;
+ st->wsum -= entity->weight;
+ if (bfqq != NULL) {
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "forget_entity: %p %d",
+ bfqq, atomic_read(&bfqq->ref));
+ bfq_put_queue(bfqq);
+ }
+}
+
+/**
+ * bfq_put_idle_entity - release the idle tree ref of an entity.
+ * @st: service tree for the entity.
+ * @entity: the entity being released.
+ */
+static void bfq_put_idle_entity(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ bfq_idle_extract(st, entity);
+ bfq_forget_entity(st, entity);
+}
+
+/**
+ * bfq_forget_idle - update the idle tree if necessary.
+ * @st: the service tree to act upon.
+ *
+ * To preserve the global O(log N) complexity we only remove one entry here;
+ * as the idle tree will not grow indefinitely this can be done safely.
+ */
+static void bfq_forget_idle(struct bfq_service_tree *st)
+{
+ struct bfq_entity *first_idle = st->first_idle;
+ struct bfq_entity *last_idle = st->last_idle;
+
+ if (RB_EMPTY_ROOT(&st->active) && last_idle != NULL &&
+ !bfq_gt(last_idle->finish, st->vtime)) {
+ /*
+ * Forget the whole idle tree, increasing the vtime past
+ * the last finish time of idle entities.
+ */
+ st->vtime = last_idle->finish;
+ }
+
+ if (first_idle != NULL && !bfq_gt(first_idle->finish, st->vtime))
+ bfq_put_idle_entity(st, first_idle);
+}
+
+static struct bfq_service_tree *
+__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
+ struct bfq_entity *entity)
+{
+ struct bfq_service_tree *new_st = old_st;
+
+ if (entity->ioprio_changed) {
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ BUG_ON(old_st->wsum < entity->weight);
+ old_st->wsum -= entity->weight;
+
+ if (entity->new_weight != entity->orig_weight) {
+ entity->orig_weight = entity->new_weight;
+ entity->ioprio =
+ bfq_weight_to_ioprio(entity->orig_weight);
+ } else if (entity->new_ioprio != entity->ioprio) {
+ entity->ioprio = entity->new_ioprio;
+ entity->orig_weight =
+ bfq_ioprio_to_weight(entity->ioprio);
+ } else
+ entity->new_weight = entity->orig_weight =
+ bfq_ioprio_to_weight(entity->ioprio);
+
+ entity->ioprio_class = entity->new_ioprio_class;
+ entity->ioprio_changed = 0;
+
+ /*
+ * NOTE: here we may be changing the weight too early,
+ * this will cause unfairness. The correct approach
+ * would have required additional complexity to defer
+ * weight changes to the proper time instants (i.e.,
+ * when entity->finish <= old_st->vtime).
+ */
+ new_st = bfq_entity_service_tree(entity);
+ entity->weight = entity->orig_weight *
+ (bfqq != NULL ? bfqq->raising_coeff : 1);
+ new_st->wsum += entity->weight;
+
+ if (new_st != old_st)
+ entity->start = new_st->vtime;
+ }
+
+ return new_st;
+}
+
+/**
+ * bfq_bfqq_served - update the scheduler status after selection for service.
+ * @bfqq: the queue being served.
+ * @served: bytes to transfer.
+ *
+ * NOTE: this can be optimized, as the timestamps of upper level entities
+ * are synchronized every time a new bfqq is selected for service. By now,
+ * we keep it to better check consistency.
+ */
+static void bfq_bfqq_served(struct bfq_queue *bfqq, unsigned long served)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+ struct bfq_service_tree *st;
+
+ for_each_entity(entity) {
+ st = bfq_entity_service_tree(entity);
+
+ entity->service += served;
+ BUG_ON(entity->service > entity->budget);
+ BUG_ON(st->wsum == 0);
+
+ st->vtime += bfq_delta(served, st->wsum);
+ bfq_forget_idle(st);
+ }
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %lu secs", served);
+}
+
+/**
+ * bfq_bfqq_charge_full_budget - set the service to the entity budget.
+ * @bfqq: the queue that needs a service update.
+ *
+ * When it's not possible to be fair in the service domain, because
+ * a queue is not consuming its budget fast enough (the meaning of
+ * fast depends on the timeout parameter), we charge it a full
+ * budget. In this way we should obtain a sort of time-domain
+ * fairness among all the seeky/slow queues.
+ */
+static inline void bfq_bfqq_charge_full_budget(struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "charge_full_budget");
+
+ bfq_bfqq_served(bfqq, entity->budget - entity->service);
+}
+
+/**
+ * __bfq_activate_entity - activate an entity.
+ * @entity: the entity being activated.
+ *
+ * Called whenever an entity is activated, i.e., it is not active and one
+ * of its children receives a new request, or has to be reactivated due to
+ * budget exhaustion. It uses the current budget of the entity (and the
+ * service received if @entity is active) of the queue to calculate its
+ * timestamps.
+ */
+static void __bfq_activate_entity(struct bfq_entity *entity)
+{
+ struct bfq_sched_data *sd = entity->sched_data;
+ struct bfq_service_tree *st = bfq_entity_service_tree(entity);
+
+ if (entity == sd->active_entity) {
+ BUG_ON(entity->tree != NULL);
+ /*
+ * If we are requeueing the current entity we have
+ * to take care of not charging to it service it has
+ * not received.
+ */
+ bfq_calc_finish(entity, entity->service);
+ entity->start = entity->finish;
+ sd->active_entity = NULL;
+ } else if (entity->tree == &st->active) {
+ /*
+ * Requeueing an entity due to a change of some
+ * next_active entity below it. We reuse the old
+ * start time.
+ */
+ bfq_active_extract(st, entity);
+ } else if (entity->tree == &st->idle) {
+ /*
+ * Must be on the idle tree, bfq_idle_extract() will
+ * check for that.
+ */
+ bfq_idle_extract(st, entity);
+ entity->start = bfq_gt(st->vtime, entity->finish) ?
+ st->vtime : entity->finish;
+ } else {
+ /*
+ * The finish time of the entity may be invalid, and
+ * it is in the past for sure, otherwise the queue
+ * would have been on the idle tree.
+ */
+ entity->start = st->vtime;
+ st->wsum += entity->weight;
+ bfq_get_entity(entity);
+
+ BUG_ON(entity->on_st);
+ entity->on_st = 1;
+ }
+
+ st = __bfq_entity_update_weight_prio(st, entity);
+ bfq_calc_finish(entity, entity->budget);
+ bfq_active_insert(st, entity);
+}
+
+/**
+ * bfq_activate_entity - activate an entity and its ancestors if necessary.
+ * @entity: the entity to activate.
+ *
+ * Activate @entity and all the entities on the path from it to the root.
+ */
+static void bfq_activate_entity(struct bfq_entity *entity)
+{
+ struct bfq_sched_data *sd;
+
+ for_each_entity(entity) {
+ __bfq_activate_entity(entity);
+
+ sd = entity->sched_data;
+ if (!bfq_update_next_active(sd))
+ /*
+ * No need to propagate the activation to the
+ * upper entities, as they will be updated when
+ * the active entity is rescheduled.
+ */
+ break;
+ }
+}
+
+/**
+ * __bfq_deactivate_entity - deactivate an entity from its service tree.
+ * @entity: the entity to deactivate.
+ * @requeue: if false, the entity will not be put into the idle tree.
+ *
+ * Deactivate an entity, independently from its previous state. If the
+ * entity was not on a service tree just return, otherwise if it is on
+ * any scheduler tree, extract it from that tree, and if necessary
+ * and if the caller did not specify @requeue, put it on the idle tree.
+ *
+ * Return %1 if the caller should update the entity hierarchy, i.e.,
+ * if the entity was under service or if it was the next_active for
+ * its sched_data; return %0 otherwise.
+ */
+static int __bfq_deactivate_entity(struct bfq_entity *entity, int requeue)
+{
+ struct bfq_sched_data *sd = entity->sched_data;
+ struct bfq_service_tree *st = bfq_entity_service_tree(entity);
+ int was_active = entity == sd->active_entity;
+ int ret = 0;
+
+ if (!entity->on_st)
+ return 0;
+
+ BUG_ON(was_active && entity->tree != NULL);
+
+ if (was_active) {
+ bfq_calc_finish(entity, entity->service);
+ sd->active_entity = NULL;
+ } else if (entity->tree == &st->active)
+ bfq_active_extract(st, entity);
+ else if (entity->tree == &st->idle)
+ bfq_idle_extract(st, entity);
+ else if (entity->tree != NULL)
+ BUG();
+
+ if (was_active || sd->next_active == entity)
+ ret = bfq_update_next_active(sd);
+
+ if (!requeue || !bfq_gt(entity->finish, st->vtime))
+ bfq_forget_entity(st, entity);
+ else
+ bfq_idle_insert(st, entity);
+
+ BUG_ON(sd->active_entity == entity);
+ BUG_ON(sd->next_active == entity);
+
+ return ret;
+}
+
+/**
+ * bfq_deactivate_entity - deactivate an entity.
+ * @entity: the entity to deactivate.
+ * @requeue: true if the entity can be put on the idle tree
+ */
+static void bfq_deactivate_entity(struct bfq_entity *entity, int requeue)
+{
+ struct bfq_sched_data *sd;
+ struct bfq_entity *parent;
+
+ for_each_entity_safe(entity, parent) {
+ sd = entity->sched_data;
+
+ if (!__bfq_deactivate_entity(entity, requeue))
+ /*
+ * The parent entity is still backlogged, and
+ * we don't need to update it as it is still
+ * under service.
+ */
+ break;
+
+ if (sd->next_active != NULL)
+ /*
+ * The parent entity is still backlogged and
+ * the budgets on the path towards the root
+ * need to be updated.
+ */
+ goto update;
+
+ /*
+ * If we reach there the parent is no more backlogged and
+ * we want to propagate the dequeue upwards.
+ */
+ requeue = 1;
+ }
+
+ return;
+
+update:
+ entity = parent;
+ for_each_entity(entity) {
+ __bfq_activate_entity(entity);
+
+ sd = entity->sched_data;
+ if (!bfq_update_next_active(sd))
+ break;
+ }
+}
+
+/**
+ * bfq_update_vtime - update vtime if necessary.
+ * @st: the service tree to act upon.
+ *
+ * If necessary update the service tree vtime to have at least one
+ * eligible entity, skipping to its start time. Assumes that the
+ * active tree of the device is not empty.
+ *
+ * NOTE: this hierarchical implementation updates vtimes quite often,
+ * we may end up with reactivated tasks getting timestamps after a
+ * vtime skip done because we needed a ->first_active entity on some
+ * intermediate node.
+ */
+static void bfq_update_vtime(struct bfq_service_tree *st)
+{
+ struct bfq_entity *entry;
+ struct rb_node *node = st->active.rb_node;
+
+ entry = rb_entry(node, struct bfq_entity, rb_node);
+ if (bfq_gt(entry->min_start, st->vtime)) {
+ st->vtime = entry->min_start;
+ bfq_forget_idle(st);
+ }
+}
+
+/**
+ * bfq_first_active - find the eligible entity with the smallest finish time
+ * @st: the service tree to select from.
+ *
+ * This function searches the first schedulable entity, starting from the
+ * root of the tree and going on the left every time on this side there is
+ * a subtree with at least one eligible (start >= vtime) entity. The path
+ * on the right is followed only if a) the left subtree contains no eligible
+ * entities and b) no eligible entity has been found yet.
+ */
+static struct bfq_entity *bfq_first_active_entity(struct bfq_service_tree *st)
+{
+ struct bfq_entity *entry, *first = NULL;
+ struct rb_node *node = st->active.rb_node;
+
+ while (node != NULL) {
+ entry = rb_entry(node, struct bfq_entity, rb_node);
+left:
+ if (!bfq_gt(entry->start, st->vtime))
+ first = entry;
+
+ BUG_ON(bfq_gt(entry->min_start, st->vtime));
+
+ if (node->rb_left != NULL) {
+ entry = rb_entry(node->rb_left,
+ struct bfq_entity, rb_node);
+ if (!bfq_gt(entry->min_start, st->vtime)) {
+ node = node->rb_left;
+ goto left;
+ }
+ }
+ if (first != NULL)
+ break;
+ node = node->rb_right;
+ }
+
+ BUG_ON(first == NULL && !RB_EMPTY_ROOT(&st->active));
+ return first;
+}
+
+/**
+ * __bfq_lookup_next_entity - return the first eligible entity in @st.
+ * @st: the service tree.
+ *
+ * Update the virtual time in @st and return the first eligible entity
+ * it contains.
+ */
+static struct bfq_entity *__bfq_lookup_next_entity(struct bfq_service_tree *st,
+ bool force)
+{
+ struct bfq_entity *entity, *new_next_active = NULL;
+
+ if (RB_EMPTY_ROOT(&st->active))
+ return NULL;
+
+ bfq_update_vtime(st);
+ entity = bfq_first_active_entity(st);
+ BUG_ON(bfq_gt(entity->start, st->vtime));
+
+ /*
+ * If the chosen entity does not match with the sched_data's
+ * next_active and we are forcedly serving the IDLE priority
+ * class tree, bubble up budget update.
+ */
+ if (unlikely(force && entity != entity->sched_data->next_active)) {
+ new_next_active = entity;
+ for_each_entity(new_next_active)
+ bfq_update_budget(new_next_active);
+ }
+
+ return entity;
+}
+
+/**
+ * bfq_lookup_next_entity - return the first eligible entity in @sd.
+ * @sd: the sched_data.
+ * @extract: if true the returned entity will be also extracted from @sd.
+ *
+ * NOTE: since we cache the next_active entity at each level of the
+ * hierarchy, the complexity of the lookup can be decreased with
+ * absolutely no effort just returning the cached next_active value;
+ * we prefer to do full lookups to test the consistency of * the data
+ * structures.
+ */
+static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
+ int extract,
+ struct bfq_data *bfqd)
+{
+ struct bfq_service_tree *st = sd->service_tree;
+ struct bfq_entity *entity;
+ int i=0;
+
+ BUG_ON(sd->active_entity != NULL);
+
+ if (bfqd != NULL &&
+ jiffies - bfqd->bfq_class_idle_last_service > BFQ_CL_IDLE_TIMEOUT) {
+ entity = __bfq_lookup_next_entity(st + BFQ_IOPRIO_CLASSES - 1, true);
+ if (entity != NULL) {
+ i = BFQ_IOPRIO_CLASSES - 1;
+ bfqd->bfq_class_idle_last_service = jiffies;
+ sd->next_active = entity;
+ }
+ }
+ for (; i < BFQ_IOPRIO_CLASSES; i++) {
+ entity = __bfq_lookup_next_entity(st + i, false);
+ if (entity != NULL) {
+ if (extract) {
+ bfq_check_next_active(sd, entity);
+ bfq_active_extract(st + i, entity);
+ sd->active_entity = entity;
+ sd->next_active = NULL;
+ }
+ break;
+ }
+ }
+
+ return entity;
+}
+
+/*
+ * Get next queue for service.
+ */
+static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd)
+{
+ struct bfq_entity *entity = NULL;
+ struct bfq_sched_data *sd;
+ struct bfq_queue *bfqq;
+
+ BUG_ON(bfqd->active_queue != NULL);
+
+ if (bfqd->busy_queues == 0)
+ return NULL;
+
+ sd = &bfqd->root_group->sched_data;
+ for (; sd != NULL; sd = entity->my_sched_data) {
+ entity = bfq_lookup_next_entity(sd, 1, bfqd);
+ BUG_ON(entity == NULL);
+ entity->service = 0;
+ }
+
+ bfqq = bfq_entity_to_bfqq(entity);
+ BUG_ON(bfqq == NULL);
+
+ return bfqq;
+}
+
+/*
+ * Forced extraction of the given queue.
+ */
+static void bfq_get_next_queue_forced(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity;
+ struct bfq_sched_data *sd;
+
+ BUG_ON(bfqd->active_queue != NULL);
+
+ entity = &bfqq->entity;
+ /*
+ * Bubble up extraction/update from the leaf to the root.
+ */
+ for_each_entity(entity) {
+ sd = entity->sched_data;
+ bfq_update_budget(entity);
+ bfq_update_vtime(bfq_entity_service_tree(entity));
+ bfq_active_extract(bfq_entity_service_tree(entity), entity);
+ sd->active_entity = entity;
+ sd->next_active = NULL;
+ entity->service = 0;
+ }
+
+ return;
+}
+
+static void __bfq_bfqd_reset_active(struct bfq_data *bfqd)
+{
+ if (bfqd->active_cic != NULL) {
+ put_io_context(bfqd->active_cic->ioc);
+ bfqd->active_cic = NULL;
+ }
+
+ bfqd->active_queue = NULL;
+ del_timer(&bfqd->idle_slice_timer);
+}
+
+static void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ int requeue)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+
+ if (bfqq == bfqd->active_queue)
+ __bfq_bfqd_reset_active(bfqd);
+
+ bfq_deactivate_entity(entity, requeue);
+}
+
+static void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+
+ bfq_activate_entity(entity);
+}
+
+/*
+ * Called when the bfqq no longer has requests pending, remove it from
+ * the service tree.
+ */
+static void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ int requeue)
+{
+ BUG_ON(!bfq_bfqq_busy(bfqq));
+ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
+
+ bfq_log_bfqq(bfqd, bfqq, "del from busy");
+
+ bfq_clear_bfqq_busy(bfqq);
+
+ BUG_ON(bfqd->busy_queues == 0);
+ bfqd->busy_queues--;
+
+ bfq_deactivate_bfqq(bfqd, bfqq, requeue);
+}
+
+/*
+ * Called when an inactive queue receives a new request.
+ */
+static void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ BUG_ON(bfq_bfqq_busy(bfqq));
+ BUG_ON(bfqq == bfqd->active_queue);
+
+ bfq_log_bfqq(bfqd, bfqq, "add to busy");
+
+ bfq_activate_bfqq(bfqd, bfqq);
+
+ bfq_mark_bfqq_busy(bfqq);
+ bfqd->busy_queues++;
+}
--- /dev/null
+++ b/block/bfq.h
@@ -0,0 +1,597 @@
+/*
+ * BFQ-v5r1 for 3.0: data structures and common functions prototypes.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
+ */
+
+#ifndef _BFQ_H
+#define _BFQ_H
+
+#include <linux/blktrace_api.h>
+#include <linux/hrtimer.h>
+#include <linux/ioprio.h>
+#include <linux/rbtree.h>
+
+#define BFQ_IOPRIO_CLASSES 3
+#define BFQ_CL_IDLE_TIMEOUT HZ/5
+
+#define BFQ_MIN_WEIGHT 1
+#define BFQ_MAX_WEIGHT 1000
+
+#define BFQ_DEFAULT_GRP_WEIGHT 10
+#define BFQ_DEFAULT_GRP_IOPRIO 0
+#define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE
+
+struct bfq_entity;
+
+/**
+ * struct bfq_service_tree - per ioprio_class service tree.
+ * @active: tree for active entities (i.e., those backlogged).
+ * @idle: tree for idle entities (i.e., those not backlogged, with V <= F_i).
+ * @first_idle: idle entity with minimum F_i.
+ * @last_idle: idle entity with maximum F_i.
+ * @vtime: scheduler virtual time.
+ * @wsum: scheduler weight sum; active and idle entities contribute to it.
+ *
+ * Each service tree represents a B-WF2Q+ scheduler on its own. Each
+ * ioprio_class has its own independent scheduler, and so its own
+ * bfq_service_tree. All the fields are protected by the queue lock
+ * of the containing bfqd.
+ */
+struct bfq_service_tree {
+ struct rb_root active;
+ struct rb_root idle;
+
+ struct bfq_entity *first_idle;
+ struct bfq_entity *last_idle;
+
+ u64 vtime;
+ unsigned long wsum;
+};
+
+/**
+ * struct bfq_sched_data - multi-class scheduler.
+ * @active_entity: entity under service.
+ * @next_active: head-of-the-line entity in the scheduler.
+ * @service_tree: array of service trees, one per ioprio_class.
+ *
+ * bfq_sched_data is the basic scheduler queue. It supports three
+ * ioprio_classes, and can be used either as a toplevel queue or as
+ * an intermediate queue on a hierarchical setup.
+ * @next_active points to the active entity of the sched_data service
+ * trees that will be scheduled next.
+ *
+ * The supported ioprio_classes are the same as in CFQ, in descending
+ * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE.
+ * Requests from higher priority queues are served before all the
+ * requests from lower priority queues; among requests of the same
+ * queue requests are served according to B-WF2Q+.
+ * All the fields are protected by the queue lock of the containing bfqd.
+ */
+struct bfq_sched_data {
+ struct bfq_entity *active_entity;
+ struct bfq_entity *next_active;
+ struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES];
+};
+
+/**
+ * struct bfq_entity - schedulable entity.
+ * @rb_node: service_tree member.
+ * @on_st: flag, true if the entity is on a tree (either the active or
+ * the idle one of its service_tree).
+ * @finish: B-WF2Q+ finish timestamp (aka F_i).
+ * @start: B-WF2Q+ start timestamp (aka S_i).
+ * @tree: tree the entity is enqueued into; %NULL if not on a tree.
+ * @min_start: minimum start time of the (active) subtree rooted at
+ * this entity; used for O(log N) lookups into active trees.
+ * @service: service received during the last round of service.
+ * @budget: budget used to calculate F_i; F_i = S_i + @budget / @weight.
+ * @weight: weight of the queue
+ * @parent: parent entity, for hierarchical scheduling.
+ * @my_sched_data: for non-leaf nodes in the cgroup hierarchy, the
+ * associated scheduler queue, %NULL on leaf nodes.
+ * @sched_data: the scheduler queue this entity belongs to.
+ * @ioprio: the ioprio in use.
+ * @new_weight: when a weight change is requested, the new weight value.
+ * @orig_weight: original weight, used to implement weight boosting
+ * @new_ioprio: when an ioprio change is requested, the new ioprio value.
+ * @ioprio_class: the ioprio_class in use.
+ * @new_ioprio_class: when an ioprio_class change is requested, the new
+ * ioprio_class value.
+ * @ioprio_changed: flag, true when the user requested a weight, ioprio or
+ * ioprio_class change.
+ *
+ * A bfq_entity is used to represent either a bfq_queue (leaf node in the
+ * cgroup hierarchy) or a bfq_group into the upper level scheduler. Each
+ * entity belongs to the sched_data of the parent group in the cgroup
+ * hierarchy. Non-leaf entities have also their own sched_data, stored
+ * in @my_sched_data.
+ *
+ * Each entity stores independently its priority values; this would
+ * allow different weights on different devices, but this
+ * functionality is not exported to userspace by now. Priorities and
+ * weights are updated lazily, first storing the new values into the
+ * new_* fields, then setting the @ioprio_changed flag. As soon as
+ * there is a transition in the entity state that allows the priority
+ * update to take place the effective and the requested priority
+ * values are synchronized.
+ *
+ * Unless cgroups are used, the weight value is calculated from the
+ * ioprio to export the same interface as CFQ. When dealing with
+ * ``well-behaved'' queues (i.e., queues that do not spend too much
+ * time to consume their budget and have true sequential behavior, and
+ * when there are no external factors breaking anticipation) the
+ * relative weights at each level of the cgroups hierarchy should be
+ * guaranteed. All the fields are protected by the queue lock of the
+ * containing bfqd.
+ */
+struct bfq_entity {
+ struct rb_node rb_node;
+
+ int on_st;
+
+ u64 finish;
+ u64 start;
+
+ struct rb_root *tree;
+
+ u64 min_start;
+
+ unsigned long service, budget;
+ unsigned short weight, new_weight;
+ unsigned short orig_weight;
+
+ struct bfq_entity *parent;
+
+ struct bfq_sched_data *my_sched_data;
+ struct bfq_sched_data *sched_data;
+
+ unsigned short ioprio, new_ioprio;
+ unsigned short ioprio_class, new_ioprio_class;
+
+ int ioprio_changed;
+};
+
+struct bfq_group;
+
+/**
+ * struct bfq_queue - leaf schedulable entity.
+ * @ref: reference counter.
+ * @bfqd: parent bfq_data.
+ * @new_bfqq: shared bfq_queue if queue is cooperating with
+ * one or more other queues.
+ * @pos_node: request-position tree member (see bfq_data's @rq_pos_tree).
+ * @pos_root: request-position tree root (see bfq_data's @rq_pos_tree).
+ * @sort_list: sorted list of pending requests.
+ * @next_rq: if fifo isn't expired, next request to serve.
+ * @queued: nr of requests queued in @sort_list.
+ * @allocated: currently allocated requests.
+ * @meta_pending: pending metadata requests.
+ * @fifo: fifo list of requests in sort_list.
+ * @entity: entity representing this queue in the scheduler.
+ * @max_budget: maximum budget allowed from the feedback mechanism.
+ * @budget_timeout: budget expiration (in jiffies).
+ * @dispatched: number of requests on the dispatch list or inside driver.
+ * @org_ioprio: saved ioprio during boosted periods.
+ * @org_ioprio_class: saved ioprio_class during boosted periods.
+ * @flags: status flags.
+ * @bfqq_list: node for active/idle bfqq list inside our bfqd.
+ * @seek_samples: number of seeks sampled
+ * @seek_total: sum of the distances of the seeks sampled
+ * @seek_mean: mean seek distance
+ * @last_request_pos: position of the last request enqueued
+ * @pid: pid of the process owning the queue, used for logging purposes.
+ * @last_rais_start_time: last (idle -> weight-raised) transition attempt
+ * @raising_cur_max_time: current max raising time for this queue
+ *
+ * A bfq_queue is a leaf request queue; it can be associated to an io_context
+ * or more (if it is an async one). @cgroup holds a reference to the
+ * cgroup, to be sure that it does not disappear while a bfqq still
+ * references it (mostly to avoid races between request issuing and task
+ * migration followed by cgroup distruction).
+ * All the fields are protected by the queue lock of the containing bfqd.
+ */
+struct bfq_queue {
+ atomic_t ref;
+ struct bfq_data *bfqd;
+
+ /* fields for cooperating queues handling */
+ struct bfq_queue *new_bfqq;
+ struct rb_node pos_node;
+ struct rb_root *pos_root;
+
+ struct rb_root sort_list;
+ struct request *next_rq;
+ int queued[2];
+ int allocated[2];
+ int meta_pending;
+ struct list_head fifo;
+
+ struct bfq_entity entity;
+
+ unsigned long max_budget;
+ unsigned long budget_timeout;
+
+ int dispatched;
+
+ unsigned short org_ioprio;
+ unsigned short org_ioprio_class;
+
+ unsigned int flags;
+
+ struct list_head bfqq_list;
+
+ unsigned int seek_samples;
+ u64 seek_total;
+ sector_t seek_mean;
+ sector_t last_request_pos;
+
+ pid_t pid;
+
+ /* weight-raising fields */
+ unsigned int raising_cur_max_time;
+ u64 last_rais_start_finish, soft_rt_next_start;
+ unsigned int raising_coeff;
+};
+
+/**
+ * struct bfq_data - per device data structure.
+ * @queue: request queue for the managed device.
+ * @root_group: root bfq_group for the device.
+ * @rq_pos_tree: rbtree sorted by next_request position,
+ * used when determining if two or more queues
+ * have interleaving requests (see bfq_close_cooperator).
+ * @busy_queues: number of bfq_queues containing requests (including the
+ * queue under service, even if it is idling).
+ * @queued: number of queued requests.
+ * @rq_in_driver: number of requests dispatched and waiting for completion.
+ * @sync_flight: number of sync requests in the driver.
+ * @max_rq_in_driver: max number of reqs in driver in the last @hw_tag_samples
+ * completed requests .
+ * @hw_tag_samples: nr of samples used to calculate hw_tag.
+ * @hw_tag: flag set to one if the driver is showing a queueing behavior.
+ * @budgets_assigned: number of budgets assigned.
+ * @idle_slice_timer: timer set when idling for the next sequential request
+ * from the queue under service.
+ * @unplug_work: delayed work to restart dispatching on the request queue.
+ * @active_queue: bfq_queue under service.
+ * @active_cic: cfq_io_context (cic) associated with the @active_queue.
+ * @last_position: on-disk position of the last served request.
+ * @last_budget_start: beginning of the last budget.
+ * @last_idling_start: beginning of the last idle slice.
+ * @peak_rate: peak transfer rate observed for a budget.
+ * @peak_rate_samples: number of samples used to calculate @peak_rate.
+ * @bfq_max_budget: maximum budget allotted to a bfq_queue before rescheduling.
+ * @cic_index: use small consequent indexes as radix tree keys to reduce depth
+ * @cic_list: list of all the cics active on the bfq_data device.
+ * @group_list: list of all the bfq_groups active on the device.
+ * @active_list: list of all the bfq_queues active on the device.
+ * @idle_list: list of all the bfq_queues idle on the device.
+ * @bfq_quantum: max number of requests dispatched per dispatch round.
+ * @bfq_fifo_expire: timeout for async/sync requests; when it expires
+ * requests are served in fifo order.
+ * @bfq_back_penalty: weight of backward seeks wrt forward ones.
+ * @bfq_back_max: maximum allowed backward seek.
+ * @bfq_slice_idle: maximum idling time.
+ * @bfq_user_max_budget: user-configured max budget value (0 for auto-tuning).
+ * @bfq_max_budget_async_rq: maximum budget (in nr of requests) allotted to
+ * async queues.
+ * @bfq_timeout: timeout for bfq_queues to consume their budget; used to
+ * to prevent seeky queues to impose long latencies to well
+ * behaved ones (this also implies that seeky queues cannot
+ * receive guarantees in the service domain; after a timeout
+ * they are charged for the whole allocated budget, to try
+ * to preserve a behavior reasonably fair among them, but
+ * without service-domain guarantees).
+ * @bfq_raising_coeff: Maximum factor by which the weight of a boosted
+ * queue is multiplied
+ * @bfq_raising_max_time: maximum duration of a weight-raising period (jiffies)
+ * @bfq_raising_rt_max_time: maximum duration for soft real-time processes
+ * @bfq_raising_min_idle_time: minimum idle period after which weight-raising
+ * may be reactivated for a queue (in jiffies)
+ * @bfq_raising_min_inter_arr_async: minimum period between request arrivals
+ * after which weight-raising may be
+ * reactivated for an already busy queue
+ * (in jiffies)
+ * @bfq_raising_max_softrt_rate: max service-rate for a soft real-time queue,
+ * sectors per seconds
+ * @RT_prod: cached value of the product R*T used for computing the maximum
+ * duration of the weight raising automatically
+ * @oom_bfqq: fallback dummy bfqq for extreme OOM conditions
+ *
+ * All the fields are protected by the @queue lock.
+ */
+struct bfq_data {
+ struct request_queue *queue;
+
+ struct bfq_group *root_group;
+
+ struct rb_root rq_pos_tree;
+
+ int busy_queues;
+ int queued;
+ int rq_in_driver;
+ int sync_flight;
+
+ int max_rq_in_driver;
+ int hw_tag_samples;
+ int hw_tag;
+
+ int budgets_assigned;
+
+ struct timer_list idle_slice_timer;
+ struct work_struct unplug_work;
+
+ struct bfq_queue *active_queue;
+ struct cfq_io_context *active_cic;
+
+ sector_t last_position;
+
+ ktime_t last_budget_start;
+ ktime_t last_idling_start;
+ int peak_rate_samples;
+ u64 peak_rate;
+ unsigned long bfq_max_budget;
+
+ unsigned int cic_index;
+ struct list_head cic_list;
+ struct hlist_head group_list;
+ struct list_head active_list;
+ struct list_head idle_list;
+
+ unsigned int bfq_quantum;
+ unsigned int bfq_fifo_expire[2];
+ unsigned int bfq_back_penalty;
+ unsigned int bfq_back_max;
+ unsigned int bfq_slice_idle;
+ u64 bfq_class_idle_last_service;
+
+ unsigned int bfq_user_max_budget;
+ unsigned int bfq_max_budget_async_rq;
+ unsigned int bfq_timeout[2];
+
+ bool low_latency;
+
+ /* parameters of the low_latency heuristics */
+ unsigned int bfq_raising_coeff;
+ unsigned int bfq_raising_max_time;
+ unsigned int bfq_raising_rt_max_time;
+ unsigned int bfq_raising_min_idle_time;
+ unsigned int bfq_raising_min_inter_arr_async;
+ unsigned int bfq_raising_max_softrt_rate;
+ u64 RT_prod;
+
+ struct bfq_queue oom_bfqq;
+};
+
+enum bfqq_state_flags {
+ BFQ_BFQQ_FLAG_busy = 0, /* has requests or is under service */
+ BFQ_BFQQ_FLAG_wait_request, /* waiting for a request */
+ BFQ_BFQQ_FLAG_must_alloc, /* must be allowed rq alloc */
+ BFQ_BFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
+ BFQ_BFQQ_FLAG_idle_window, /* slice idling enabled */
+ BFQ_BFQQ_FLAG_prio_changed, /* task priority has changed */
+ BFQ_BFQQ_FLAG_sync, /* synchronous queue */
+ BFQ_BFQQ_FLAG_budget_new, /* no completion with this budget */
+ BFQ_BFQQ_FLAG_coop, /* bfqq is shared */
+ BFQ_BFQQ_FLAG_split_coop, /* shared bfqq will be splitted */
+ BFQ_BFQQ_FLAG_some_coop_idle, /* some cooperator is inactive */
+};
+
+#define BFQ_BFQQ_FNS(name) \
+static inline void bfq_mark_bfqq_##name(struct bfq_queue *bfqq) \
+{ \
+ (bfqq)->flags |= (1 << BFQ_BFQQ_FLAG_##name); \
+} \
+static inline void bfq_clear_bfqq_##name(struct bfq_queue *bfqq) \
+{ \
+ (bfqq)->flags &= ~(1 << BFQ_BFQQ_FLAG_##name); \
+} \
+static inline int bfq_bfqq_##name(const struct bfq_queue *bfqq) \
+{ \
+ return ((bfqq)->flags & (1 << BFQ_BFQQ_FLAG_##name)) != 0; \
+}
+
+BFQ_BFQQ_FNS(busy);
+BFQ_BFQQ_FNS(wait_request);
+BFQ_BFQQ_FNS(must_alloc);
+BFQ_BFQQ_FNS(fifo_expire);
+BFQ_BFQQ_FNS(idle_window);
+BFQ_BFQQ_FNS(prio_changed);
+BFQ_BFQQ_FNS(sync);
+BFQ_BFQQ_FNS(budget_new);
+BFQ_BFQQ_FNS(coop);
+BFQ_BFQQ_FNS(split_coop);
+BFQ_BFQQ_FNS(some_coop_idle);
+#undef BFQ_BFQQ_FNS
+
+/* Logging facilities. */
+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \
+ blk_add_trace_msg((bfqd)->queue, "bfq%d " fmt, (bfqq)->pid, ##args)
+
+#define bfq_log(bfqd, fmt, args...) \
+ blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
+
+/* Expiration reasons. */
+enum bfqq_expiration {
+ BFQ_BFQQ_TOO_IDLE = 0, /* queue has been idling for too long */
+ BFQ_BFQQ_BUDGET_TIMEOUT, /* budget took too long to be used */
+ BFQ_BFQQ_BUDGET_EXHAUSTED, /* budget consumed */
+ BFQ_BFQQ_NO_MORE_REQUESTS, /* the queue has no more requests */
+};
+
+#ifdef CONFIG_CGROUP_BFQIO
+/**
+ * struct bfq_group - per (device, cgroup) data structure.
+ * @entity: schedulable entity to insert into the parent group sched_data.
+ * @sched_data: own sched_data, to contain child entities (they may be
+ * both bfq_queues and bfq_groups).
+ * @group_node: node to be inserted into the bfqio_cgroup->group_data
+ * list of the containing cgroup's bfqio_cgroup.
+ * @bfqd_node: node to be inserted into the @bfqd->group_list list
+ * of the groups active on the same device; used for cleanup.
+ * @bfqd: the bfq_data for the device this group acts upon.
+ * @async_bfqq: array of async queues for all the tasks belonging to
+ * the group, one queue per ioprio value per ioprio_class,
+ * except for the idle class that has only one queue.
+ * @async_idle_bfqq: async queue for the idle class (ioprio is ignored).
+ * @my_entity: pointer to @entity, %NULL for the toplevel group; used
+ * to avoid too many special cases during group creation/migration.
+ *
+ * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
+ * there is a set of bfq_groups, each one collecting the lower-level
+ * entities belonging to the group that are acting on the same device.
+ *
+ * Locking works as follows:
+ * o @group_node is protected by the bfqio_cgroup lock, and is accessed
+ * via RCU from its readers.
+ * o @bfqd is protected by the queue lock, RCU is used to access it
+ * from the readers.
+ * o All the other fields are protected by the @bfqd queue lock.
+ */
+struct bfq_group {
+ struct bfq_entity entity;
+ struct bfq_sched_data sched_data;
+
+ struct hlist_node group_node;
+ struct hlist_node bfqd_node;
+
+ void *bfqd;
+
+ struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
+ struct bfq_queue *async_idle_bfqq;
+
+ struct bfq_entity *my_entity;
+};
+
+/**
+ * struct bfqio_cgroup - bfq cgroup data structure.
+ * @css: subsystem state for bfq in the containing cgroup.
+ * @weight: cgroup weight.
+ * @ioprio: cgroup ioprio.
+ * @ioprio_class: cgroup ioprio_class.
+ * @lock: spinlock that protects @ioprio, @ioprio_class and @group_data.
+ * @group_data: list containing the bfq_group belonging to this cgroup.
+ *
+ * @group_data is accessed using RCU, with @lock protecting the updates,
+ * @ioprio and @ioprio_class are protected by @lock.
+ */
+struct bfqio_cgroup {
+ struct cgroup_subsys_state css;
+
+ unsigned short weight, ioprio, ioprio_class;
+
+ spinlock_t lock;
+ struct hlist_head group_data;
+};
+#else
+struct bfq_group {
+ struct bfq_sched_data sched_data;
+
+ struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
+ struct bfq_queue *async_idle_bfqq;
+};
+#endif
+
+static inline struct bfq_service_tree *
+bfq_entity_service_tree(struct bfq_entity *entity)
+{
+ struct bfq_sched_data *sched_data = entity->sched_data;
+ unsigned int idx = entity->ioprio_class - 1;
+
+ BUG_ON(idx >= BFQ_IOPRIO_CLASSES);
+ BUG_ON(sched_data == NULL);
+
+ return sched_data->service_tree + idx;
+}
+
+static inline struct bfq_queue *cic_to_bfqq(struct cfq_io_context *cic,
+ int is_sync)
+{
+ return cic->cfqq[!!is_sync];
+}
+
+static inline void cic_set_bfqq(struct cfq_io_context *cic,
+ struct bfq_queue *bfqq, int is_sync)
+{
+ cic->cfqq[!!is_sync] = bfqq;
+}
+
+static inline void call_for_each_cic(struct io_context *ioc,
+ void (*func)(struct io_context *,
+ struct cfq_io_context *))
+{
+ struct cfq_io_context *cic;
+ struct hlist_node *n;
+
+ rcu_read_lock();
+ hlist_for_each_entry_rcu(cic, n, &ioc->bfq_cic_list, cic_list)
+ func(ioc, cic);
+ rcu_read_unlock();
+}
+
+#define CIC_DEAD_KEY 1ul
+#define CIC_DEAD_INDEX_SHIFT 1
+
+static inline void *bfqd_dead_key(struct bfq_data *bfqd)
+{
+ return (void *)(bfqd->cic_index << CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY);
+}
+
+/**
+ * bfq_get_bfqd_locked - get a lock to a bfqd using a RCU protected pointer.
+ * @ptr: a pointer to a bfqd.
+ * @flags: storage for the flags to be saved.
+ *
+ * This function allows cic->key and bfqg->bfqd to be protected by the
+ * queue lock of the bfqd they reference; the pointer is dereferenced
+ * under RCU, so the storage for bfqd is assured to be safe as long
+ * as the RCU read side critical section does not end. After the
+ * bfqd->queue->queue_lock is taken the pointer is rechecked, to be
+ * sure that no other writer accessed it. If we raced with a writer,
+ * the function returns NULL, with the queue unlocked, otherwise it
+ * returns the dereferenced pointer, with the queue locked.
+ */
+static inline struct bfq_data *bfq_get_bfqd_locked(void **ptr,
+ unsigned long *flags)
+{
+ struct bfq_data *bfqd;
+
+ rcu_read_lock();
+ bfqd = rcu_dereference(*(struct bfq_data **)ptr);
+
+ if (bfqd != NULL && !((unsigned long) bfqd & CIC_DEAD_KEY)) {
+ spin_lock_irqsave(bfqd->queue->queue_lock, *flags);
+ if (*ptr == bfqd)
+ goto out;
+ spin_unlock_irqrestore(bfqd->queue->queue_lock, *flags);
+ }
+
+ bfqd = NULL;
+out:
+ rcu_read_unlock();
+ return bfqd;
+}
+
+static inline void bfq_put_bfqd_unlock(struct bfq_data *bfqd,
+ unsigned long *flags)
+{
+ spin_unlock_irqrestore(bfqd->queue->queue_lock, *flags);
+}
+
+static void bfq_changed_ioprio(struct io_context *ioc,
+ struct cfq_io_context *cic);
+static void bfq_put_queue(struct bfq_queue *bfqq);
+static void bfq_dispatch_insert(struct request_queue *q, struct request *rq);
+static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
+ struct bfq_group *bfqg, int is_sync,
+ struct io_context *ioc, gfp_t gfp_mask);
+static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
+static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
+#endif
--- /dev/null
+++ b/block/row-iosched.c
@@ -0,0 +1,694 @@
+/*
+ * ROW (Read Over Write) I/O scheduler.
+ *
+ * Copyright (c) 2012, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+/* See Documentation/block/row-iosched.txt */
+
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/blkdev.h>
+#include <linux/elevator.h>
+#include <linux/bio.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/compiler.h>
+#include <linux/blktrace_api.h>
+#include <linux/jiffies.h>
+
+/*
+ * enum row_queue_prio - Priorities of the ROW queues
+ *
+ * This enum defines the priorities (and the number of queues)
+ * the requests will be disptributed to. The higher priority -
+ * the bigger is the dispatch quantum given to that queue.
+ * ROWQ_PRIO_HIGH_READ - is the higher priority queue.
+ *
+ */
+enum row_queue_prio {
+ ROWQ_PRIO_HIGH_READ = 0,
+ ROWQ_PRIO_REG_READ,
+ ROWQ_PRIO_HIGH_SWRITE,
+ ROWQ_PRIO_REG_SWRITE,
+ ROWQ_PRIO_REG_WRITE,
+ ROWQ_PRIO_LOW_READ,
+ ROWQ_PRIO_LOW_SWRITE,
+ ROWQ_MAX_PRIO,
+};
+
+/* Flags indicating whether idling is enabled on the queue */
+static const bool queue_idling_enabled[] = {
+ true, /* ROWQ_PRIO_HIGH_READ */
+ true, /* ROWQ_PRIO_REG_READ */
+ false, /* ROWQ_PRIO_HIGH_SWRITE */
+ false, /* ROWQ_PRIO_REG_SWRITE */
+ false, /* ROWQ_PRIO_REG_WRITE */
+ false, /* ROWQ_PRIO_LOW_READ */
+ false, /* ROWQ_PRIO_LOW_SWRITE */
+};
+
+/* Default values for row queues quantums in each dispatch cycle */
+static const int queue_quantum[] = {
+ 100, /* ROWQ_PRIO_HIGH_READ */
+ 100, /* ROWQ_PRIO_REG_READ */
+ 2, /* ROWQ_PRIO_HIGH_SWRITE */
+ 1, /* ROWQ_PRIO_REG_SWRITE */
+ 1, /* ROWQ_PRIO_REG_WRITE */
+ 1, /* ROWQ_PRIO_LOW_READ */
+ 1 /* ROWQ_PRIO_LOW_SWRITE */
+};
+
+/* Default values for idling on read queues */
+#define ROW_IDLE_TIME_MSEC 5 /* msec */
+#define ROW_READ_FREQ_MSEC 20 /* msec */
+
+/**
+ * struct rowq_idling_data - parameters for idling on the queue
+ * @last_insert_time: time the last request was inserted
+ * to the queue
+ * @begin_idling: flag indicating wether we should idle
+ *
+ */
+struct rowq_idling_data {
+ ktime_t last_insert_time;
+ bool begin_idling;
+};
+
+/**
+ * struct row_queue - requests grouping structure
+ * @rdata: parent row_data structure
+ * @fifo: fifo of requests
+ * @prio: queue priority (enum row_queue_prio)
+ * @nr_dispatched: number of requests already dispatched in
+ * the current dispatch cycle
+ * @slice: number of requests to dispatch in a cycle
+ * @idle_data: data for idling on queues
+ *
+ */
+struct row_queue {
+ struct row_data *rdata;
+ struct list_head fifo;
+ enum row_queue_prio prio;
+
+ unsigned int nr_dispatched;
+ unsigned int slice;
+
+ /* used only for READ queues */
+ struct rowq_idling_data idle_data;
+};
+
+/**
+ * struct idling_data - data for idling on empty rqueue
+ * @idle_time: idling duration (jiffies)
+ * @freq: min time between two requests that
+ * triger idling (msec)
+ * @idle_work: pointer to struct delayed_work
+ *
+ */
+struct idling_data {
+ unsigned long idle_time;
+ u32 freq;
+
+ struct workqueue_struct *idle_workqueue;
+ struct delayed_work idle_work;
+};
+
+/**
+ * struct row_queue - Per block device rqueue structure
+ * @dispatch_queue: dispatch rqueue
+ * @row_queues: array of priority request queues with
+ * dispatch quantum per rqueue
+ * @curr_queue: index in the row_queues array of the
+ * currently serviced rqueue
+ * @read_idle: data for idling after READ request
+ * @nr_reqs: nr_reqs[0] holds the number of all READ requests in
+ * scheduler, nr_reqs[1] holds the number of all WRITE
+ * requests in scheduler
+ * @cycle_flags: used for marking unserved queueus
+ *
+ */
+struct row_data {
+ struct request_queue *dispatch_queue;
+
+ struct {
+ struct row_queue rqueue;
+ int disp_quantum;
+ } row_queues[ROWQ_MAX_PRIO];
+
+ enum row_queue_prio curr_queue;
+
+ struct idling_data read_idle;
+ unsigned int nr_reqs[2];
+
+ unsigned int cycle_flags;
+};
+
+#define RQ_ROWQ(rq) ((struct row_queue *) ((rq)->elevator_private[0]))
+
+#define row_log(q, fmt, args...) \
+ blk_add_trace_msg(q, "%s():" fmt , __func__, ##args)
+#define row_log_rowq(rdata, rowq_id, fmt, args...) \
+ blk_add_trace_msg(rdata->dispatch_queue, "rowq%d " fmt, \
+ rowq_id, ##args)
+
+static inline void row_mark_rowq_unserved(struct row_data *rd,
+ enum row_queue_prio qnum)
+{
+ rd->cycle_flags |= (1 << qnum);
+}
+
+static inline void row_clear_rowq_unserved(struct row_data *rd,
+ enum row_queue_prio qnum)
+{
+ rd->cycle_flags &= ~(1 << qnum);
+}
+
+static inline int row_rowq_unserved(struct row_data *rd,
+ enum row_queue_prio qnum)
+{
+ return rd->cycle_flags & (1 << qnum);
+}
+
+/******************** Static helper functions ***********************/
+/*
+ * kick_queue() - Wake up device driver queue thread
+ * @work: pointer to struct work_struct
+ *
+ * This is a idling delayed work function. It's purpose is to wake up the
+ * device driver in order for it to start fetching requests.
+ *
+ */
+static void kick_queue(struct work_struct *work)
+{
+ struct delayed_work *idle_work = to_delayed_work(work);
+ struct idling_data *read_data =
+ container_of(idle_work, struct idling_data, idle_work);
+ struct row_data *rd =
+ container_of(read_data, struct row_data, read_idle);
+
+ row_log_rowq(rd, rd->curr_queue, "Performing delayed work");
+ /* Mark idling process as done */
+ rd->row_queues[rd->curr_queue].rqueue.idle_data.begin_idling = false;
+
+ if (!(rd->nr_reqs[0] + rd->nr_reqs[1]))
+ row_log(rd->dispatch_queue, "No requests in scheduler");
+ else {
+ spin_lock_irq(rd->dispatch_queue->queue_lock);
+ __blk_run_queue(rd->dispatch_queue);
+ spin_unlock_irq(rd->dispatch_queue->queue_lock);
+ }
+}
+
+/*
+ * row_restart_disp_cycle() - Restart the dispatch cycle
+ * @rd: pointer to struct row_data
+ *
+ * This function restarts the dispatch cycle by:
+ * - Setting current queue to ROWQ_PRIO_HIGH_READ
+ * - For each queue: reset the number of requests dispatched in
+ * the cycle
+ */
+static inline void row_restart_disp_cycle(struct row_data *rd)
+{
+ int i;
+
+ for (i = 0; i < ROWQ_MAX_PRIO; i++)
+ rd->row_queues[i].rqueue.nr_dispatched = 0;
+
+ rd->curr_queue = ROWQ_PRIO_HIGH_READ;
+ row_log(rd->dispatch_queue, "Restarting cycle");
+}
+
+static inline void row_get_next_queue(struct row_data *rd)
+{
+ rd->curr_queue++;
+ if (rd->curr_queue == ROWQ_MAX_PRIO)
+ row_restart_disp_cycle(rd);
+}
+
+/******************* Elevator callback functions *********************/
+
+/*
+ * row_add_request() - Add request to the scheduler
+ * @q: requests queue
+ * @rq: request to add
+ *
+ */
+static void row_add_request(struct request_queue *q,
+ struct request *rq)
+{
+ struct row_data *rd = (struct row_data *)q->elevator->elevator_data;
+ struct row_queue *rqueue = RQ_ROWQ(rq);
+
+ list_add_tail(&rq->queuelist, &rqueue->fifo);
+ rd->nr_reqs[rq_data_dir(rq)]++;
+ rq_set_fifo_time(rq, jiffies); /* for statistics*/
+
+ if (queue_idling_enabled[rqueue->prio]) {
+ if (delayed_work_pending(&rd->read_idle.idle_work))
+ (void)cancel_delayed_work(
+ &rd->read_idle.idle_work);
+ if (ktime_to_ms(ktime_sub(ktime_get(),
+ rqueue->idle_data.last_insert_time)) <
+ rd->read_idle.freq) {
+ rqueue->idle_data.begin_idling = true;
+ row_log_rowq(rd, rqueue->prio, "Enable idling");
+ } else {
+ rqueue->idle_data.begin_idling = false;
+ row_log_rowq(rd, rqueue->prio, "Disable idling");
+ }
+
+ rqueue->idle_data.last_insert_time = ktime_get();
+ }
+ row_log_rowq(rd, rqueue->prio, "added request");
+}
+
+/*
+ * row_remove_request() - Remove given request from scheduler
+ * @q: requests queue
+ * @rq: request to remove
+ *
+ */
+static void row_remove_request(struct request_queue *q,
+ struct request *rq)
+{
+ struct row_data *rd = (struct row_data *)q->elevator->elevator_data;
+
+ rq_fifo_clear(rq);
+ rd->nr_reqs[rq_data_dir(rq)]--;
+}
+
+/*
+ * row_dispatch_insert() - move request to dispatch queue
+ * @rd: pointer to struct row_data
+ *
+ * This function moves the next request to dispatch from
+ * rd->curr_queue to the dispatch queue
+ *
+ */
+static void row_dispatch_insert(struct row_data *rd)
+{
+ struct request *rq;
+
+ rq = rq_entry_fifo(rd->row_queues[rd->curr_queue].rqueue.fifo.next);
+ row_remove_request(rd->dispatch_queue, rq);
+ elv_dispatch_add_tail(rd->dispatch_queue, rq);
+ rd->row_queues[rd->curr_queue].rqueue.nr_dispatched++;
+ row_clear_rowq_unserved(rd, rd->curr_queue);
+ row_log_rowq(rd, rd->curr_queue, " Dispatched request nr_disp = %d",
+ rd->row_queues[rd->curr_queue].rqueue.nr_dispatched);
+}
+
+/*
+ * row_choose_queue() - choose the next queue to dispatch from
+ * @rd: pointer to struct row_data
+ *
+ * Updates rd->curr_queue. Returns 1 if there are requests to
+ * dispatch, 0 if there are no requests in scheduler
+ *
+ */
+static int row_choose_queue(struct row_data *rd)
+{
+ int prev_curr_queue = rd->curr_queue;
+
+ if (!(rd->nr_reqs[0] + rd->nr_reqs[1])) {
+ row_log(rd->dispatch_queue, "No more requests in scheduler");
+ return 0;
+ }
+
+ row_get_next_queue(rd);
+
+ /*
+ * Loop over all queues to find the next queue that is not empty.
+ * Stop when you get back to curr_queue
+ */
+ while (list_empty(&rd->row_queues[rd->curr_queue].rqueue.fifo)
+ && rd->curr_queue != prev_curr_queue) {
+ /* Mark rqueue as unserved */
+ row_mark_rowq_unserved(rd, rd->curr_queue);
+ row_get_next_queue(rd);
+ }
+
+ return 1;
+}
+
+/*
+ * row_dispatch_requests() - selects the next request to dispatch
+ * @q: requests queue
+ * @force: ignored
+ *
+ * Return 0 if no requests were moved to the dispatch queue.
+ * 1 otherwise
+ *
+ */
+static int row_dispatch_requests(struct request_queue *q, int force)
+{
+ struct row_data *rd = (struct row_data *)q->elevator->elevator_data;
+ int ret = 0, currq, i;
+
+ currq = rd->curr_queue;
+
+ /*
+ * Find the first unserved queue (with higher priority then currq)
+ * that is not empty
+ */
+ for (i = 0; i < currq; i++) {
+ if (row_rowq_unserved(rd, i) &&
+ !list_empty(&rd->row_queues[i].rqueue.fifo)) {
+ row_log_rowq(rd, currq,
+ " Preemting for unserved rowq%d", i);
+ rd->curr_queue = i;
+ row_dispatch_insert(rd);
+ ret = 1;
+ goto done;
+ }
+ }
+
+ if (rd->row_queues[currq].rqueue.nr_dispatched >=
+ rd->row_queues[currq].disp_quantum) {
+ rd->row_queues[currq].rqueue.nr_dispatched = 0;
+ row_log_rowq(rd, currq, "Expiring rqueue");
+ ret = row_choose_queue(rd);
+ if (ret)
+ row_dispatch_insert(rd);
+ goto done;
+ }
+
+ /* Dispatch from curr_queue */
+ if (list_empty(&rd->row_queues[currq].rqueue.fifo)) {
+ /* check idling */
+ if (delayed_work_pending(&rd->read_idle.idle_work)) {
+ if (force) {
+ (void)cancel_delayed_work(
+ &rd->read_idle.idle_work);
+ row_log_rowq(rd, currq,
+ "Canceled delayed work - forced dispatch");
+ } else {
+ row_log_rowq(rd, currq,
+ "Delayed work pending. Exiting");
+ goto done;
+ }
+ }
+
+ if (!force && queue_idling_enabled[currq] &&
+ rd->row_queues[currq].rqueue.idle_data.begin_idling) {
+ if (!queue_delayed_work(rd->read_idle.idle_workqueue,
+ &rd->read_idle.idle_work,
+ rd->read_idle.idle_time)) {
+ row_log_rowq(rd, currq,
+ "Work already on queue!");
+ pr_err("ROW_BUG: Work already on queue!");
+ } else
+ row_log_rowq(rd, currq,
+ "Scheduled delayed work. exiting");
+ goto done;
+ } else {
+ row_log_rowq(rd, currq,
+ "Currq empty. Choose next queue");
+ ret = row_choose_queue(rd);
+ if (!ret)
+ goto done;
+ }
+ }
+
+ ret = 1;
+ row_dispatch_insert(rd);
+
+done:
+ return ret;
+}
+
+/*
+ * row_init_queue() - Init scheduler data structures
+ * @q: requests queue
+ *
+ * Return pointer to struct row_data to be saved in elevator for
+ * this dispatch queue
+ *
+ */
+static void *row_init_queue(struct request_queue *q)
+{
+
+ struct row_data *rdata;
+ int i;
+
+ rdata = kmalloc_node(sizeof(*rdata),
+ GFP_KERNEL | __GFP_ZERO, q->node);
+ if (!rdata)
+ return NULL;
+
+ for (i = 0; i < ROWQ_MAX_PRIO; i++) {
+ INIT_LIST_HEAD(&rdata->row_queues[i].rqueue.fifo);
+ rdata->row_queues[i].disp_quantum = queue_quantum[i];
+ rdata->row_queues[i].rqueue.rdata = rdata;
+ rdata->row_queues[i].rqueue.prio = i;
+ rdata->row_queues[i].rqueue.idle_data.begin_idling = false;
+ rdata->row_queues[i].rqueue.idle_data.last_insert_time =
+ ktime_set(0, 0);
+ }
+
+ /*
+ * Currently idling is enabled only for READ queues. If we want to
+ * enable it for write queues also, note that idling frequency will
+ * be the same in both cases
+ */
+ rdata->read_idle.idle_time = msecs_to_jiffies(ROW_IDLE_TIME_MSEC);
+ /* Maybe 0 on some platforms */
+ if (!rdata->read_idle.idle_time)
+ rdata->read_idle.idle_time = 1;
+ rdata->read_idle.freq = ROW_READ_FREQ_MSEC;
+ rdata->read_idle.idle_workqueue = alloc_workqueue("row_idle_work",
+ WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
+ if (!rdata->read_idle.idle_workqueue)
+ panic("Failed to create idle workqueue\n");
+ INIT_DELAYED_WORK(&rdata->read_idle.idle_work, kick_queue);
+
+ rdata->curr_queue = ROWQ_PRIO_HIGH_READ;
+ rdata->dispatch_queue = q;
+
+ rdata->nr_reqs[READ] = rdata->nr_reqs[WRITE] = 0;
+
+ return rdata;
+}
+
+/*
+ * row_exit_queue() - called on unloading the RAW scheduler
+ * @e: poiner to struct elevator_queue
+ *
+ */
+static void row_exit_queue(struct elevator_queue *e)
+{
+ struct row_data *rd = (struct row_data *)e->elevator_data;
+ int i;
+
+ for (i = 0; i < ROWQ_MAX_PRIO; i++)
+ BUG_ON(!list_empty(&rd->row_queues[i].rqueue.fifo));
+ (void)cancel_delayed_work_sync(&rd->read_idle.idle_work);
+ BUG_ON(delayed_work_pending(&rd->read_idle.idle_work));
+ destroy_workqueue(rd->read_idle.idle_workqueue);
+ kfree(rd);
+}
+
+/*
+ * row_merged_requests() - Called when 2 requests are merged
+ * @q: requests queue
+ * @rq: request the two requests were merged into
+ * @next: request that was merged
+ */
+static void row_merged_requests(struct request_queue *q, struct request *rq,
+ struct request *next)
+{
+ struct row_queue *rqueue = RQ_ROWQ(next);
+
+ list_del_init(&next->queuelist);
+
+ rqueue->rdata->nr_reqs[rq_data_dir(rq)]--;
+}
+
+/*
+ * get_queue_type() - Get queue type for a given request
+ *
+ * This is a helping function which purpose is to determine what
+ * ROW queue the given request should be added to (and
+ * dispatched from leter on)
+ *
+ * TODO: Right now only 3 queues are used REG_READ, REG_WRITE
+ * and REG_SWRITE
+ */
+static enum row_queue_prio get_queue_type(struct request *rq)
+{
+ const int data_dir = rq_data_dir(rq);
+ const bool is_sync = rq_is_sync(rq);
+
+ if (data_dir == READ)
+ return ROWQ_PRIO_REG_READ;
+ else if (is_sync)
+ return ROWQ_PRIO_REG_SWRITE;
+ else
+ return ROWQ_PRIO_REG_WRITE;
+}
+
+/*
+ * row_set_request() - Set ROW data structures associated with this request.
+ * @q: requests queue
+ * @rq: pointer to the request
+ * @gfp_mask: ignored
+ *
+ */
+static int
+row_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
+{
+ struct row_data *rd = (struct row_data *)q->elevator->elevator_data;
+ unsigned long flags;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ rq->elevator_private[0] =
+ (void *)(&rd->row_queues[get_queue_type(rq)]);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ return 0;
+}
+
+/********** Helping sysfs functions/defenitions for ROW attributes ******/
+static ssize_t row_var_show(int var, char *page)
+{
+ return snprintf(page, 100, "%d\n", var);
+}
+
+static ssize_t row_var_store(int *var, const char *page, size_t count)
+{
+ int err;
+ err = kstrtoul(page, 10, (unsigned long *)var);
+
+ return count;
+}
+
+#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
+static ssize_t __FUNC(struct elevator_queue *e, char *page) \
+{ \
+ struct row_data *rowd = e->elevator_data; \
+ int __data = __VAR; \
+ if (__CONV) \
+ __data = jiffies_to_msecs(__data); \
+ return row_var_show(__data, (page)); \
+}
+SHOW_FUNCTION(row_hp_read_quantum_show,
+ rowd->row_queues[ROWQ_PRIO_HIGH_READ].disp_quantum, 0);
+SHOW_FUNCTION(row_rp_read_quantum_show,
+ rowd->row_queues[ROWQ_PRIO_REG_READ].disp_quantum, 0);
+SHOW_FUNCTION(row_hp_swrite_quantum_show,
+ rowd->row_queues[ROWQ_PRIO_HIGH_SWRITE].disp_quantum, 0);
+SHOW_FUNCTION(row_rp_swrite_quantum_show,
+ rowd->row_queues[ROWQ_PRIO_REG_SWRITE].disp_quantum, 0);
+SHOW_FUNCTION(row_rp_write_quantum_show,
+ rowd->row_queues[ROWQ_PRIO_REG_WRITE].disp_quantum, 0);
+SHOW_FUNCTION(row_lp_read_quantum_show,
+ rowd->row_queues[ROWQ_PRIO_LOW_READ].disp_quantum, 0);
+SHOW_FUNCTION(row_lp_swrite_quantum_show,
+ rowd->row_queues[ROWQ_PRIO_LOW_SWRITE].disp_quantum, 0);
+SHOW_FUNCTION(row_read_idle_show, rowd->read_idle.idle_time, 1);
+SHOW_FUNCTION(row_read_idle_freq_show, rowd->read_idle.freq, 0);
+#undef SHOW_FUNCTION
+
+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
+static ssize_t __FUNC(struct elevator_queue *e, \
+ const char *page, size_t count) \
+{ \
+ struct row_data *rowd = e->elevator_data; \
+ int __data; \
+ int ret = row_var_store(&__data, (page), count); \
+ if (__CONV) \
+ __data = (int)msecs_to_jiffies(__data); \
+ if (__data < (MIN)) \
+ __data = (MIN); \
+ else if (__data > (MAX)) \
+ __data = (MAX); \
+ *(__PTR) = __data; \
+ return ret; \
+}
+STORE_FUNCTION(row_hp_read_quantum_store,
+&rowd->row_queues[ROWQ_PRIO_HIGH_READ].disp_quantum, 1, INT_MAX, 0);
+STORE_FUNCTION(row_rp_read_quantum_store,
+ &rowd->row_queues[ROWQ_PRIO_REG_READ].disp_quantum,
+ 1, INT_MAX, 0);
+STORE_FUNCTION(row_hp_swrite_quantum_store,
+ &rowd->row_queues[ROWQ_PRIO_HIGH_SWRITE].disp_quantum,
+ 1, INT_MAX, 0);
+STORE_FUNCTION(row_rp_swrite_quantum_store,
+ &rowd->row_queues[ROWQ_PRIO_REG_SWRITE].disp_quantum,
+ 1, INT_MAX, 0);
+STORE_FUNCTION(row_rp_write_quantum_store,
+ &rowd->row_queues[ROWQ_PRIO_REG_WRITE].disp_quantum,
+ 1, INT_MAX, 0);
+STORE_FUNCTION(row_lp_read_quantum_store,
+ &rowd->row_queues[ROWQ_PRIO_LOW_READ].disp_quantum,
+ 1, INT_MAX, 0);
+STORE_FUNCTION(row_lp_swrite_quantum_store,
+ &rowd->row_queues[ROWQ_PRIO_LOW_SWRITE].disp_quantum,
+ 1, INT_MAX, 1);
+STORE_FUNCTION(row_read_idle_store, &rowd->read_idle.idle_time, 1, INT_MAX, 1);
+STORE_FUNCTION(row_read_idle_freq_store, &rowd->read_idle.freq, 1, INT_MAX, 0);
+
+#undef STORE_FUNCTION
+
+#define ROW_ATTR(name) \
+ __ATTR(name, S_IRUGO|S_IWUSR, row_##name##_show, \
+ row_##name##_store)
+
+static struct elv_fs_entry row_attrs[] = {
+ ROW_ATTR(hp_read_quantum),
+ ROW_ATTR(rp_read_quantum),
+ ROW_ATTR(hp_swrite_quantum),
+ ROW_ATTR(rp_swrite_quantum),
+ ROW_ATTR(rp_write_quantum),
+ ROW_ATTR(lp_read_quantum),
+ ROW_ATTR(lp_swrite_quantum),
+ ROW_ATTR(read_idle),
+ ROW_ATTR(read_idle_freq),
+ __ATTR_NULL
+};
+
+static struct elevator_type iosched_row = {
+ .ops = {
+ .elevator_merge_req_fn = row_merged_requests,
+ .elevator_dispatch_fn = row_dispatch_requests,
+ .elevator_add_req_fn = row_add_request,
+ .elevator_former_req_fn = elv_rb_former_request,
+ .elevator_latter_req_fn = elv_rb_latter_request,
+ .elevator_set_req_fn = row_set_request,
+ .elevator_init_fn = row_init_queue,
+ .elevator_exit_fn = row_exit_queue,
+ },
+
+ .elevator_attrs = row_attrs,
+ .elevator_name = "row",
+ .elevator_owner = THIS_MODULE,
+};
+
+static int __init row_init(void)
+{
+ elv_register(&iosched_row);
+ return 0;
+}
+
+static void __exit row_exit(void)
+{
+ elv_unregister(&iosched_row);
+}
+
+module_init(row_init);
+module_exit(row_exit);
+
+MODULE_LICENSE("GPLv2");
+MODULE_DESCRIPTION("Read Over Write IO scheduler");
--- /dev/null
+++ b/block/zen-iosched.c
@@ -0,0 +1,277 @@
+/*
+ * Zen IO scheduler
+ * Primarily based on Noop, deadline, and SIO IO schedulers.
+ *
+ * Copyright (C) 2012 Brandon Berhent <bbedward@gmail.com>
+ *
+ * FCFS, dispatches are back-inserted, deadlines ensure fairness.
+ * Should work best with devices where there is no travel delay.
+ */
+#include <linux/blkdev.h>
+#include <linux/elevator.h>
+#include <linux/bio.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+
+enum zen_data_dir { ASYNC, SYNC };
+
+static const int sync_expire = HZ / 4; /* max time before a sync is submitted. */
+static const int async_expire = 2 * HZ; /* ditto for async, these limits are SOFT! */
+static const int fifo_batch = 1;
+
+struct zen_data {
+ /* Runtime Data */
+ /* Requests are only present on fifo_list */
+ struct list_head fifo_list[2];
+
+ unsigned int batching; /* number of sequential requests made */
+
+ /* tunables */
+ int fifo_expire[2];
+ int fifo_batch;
+};
+
+static inline struct zen_data *
+zen_get_data(struct request_queue *q) {
+ return q->elevator->elevator_data;
+}
+
+static void zen_dispatch(struct zen_data *, struct request *);
+
+static void
+zen_merged_requests(struct request_queue *q, struct request *rq,
+ struct request *next)
+{
+ /*
+ * if next expires before rq, assign its expire time to arq
+ * and move into next position (next will be deleted) in fifo
+ */
+ if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist)) {
+ if (time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
+ list_move(&rq->queuelist, &next->queuelist);
+ rq_set_fifo_time(rq, rq_fifo_time(next));
+ }
+ }
+
+ /* next request is gone */
+ rq_fifo_clear(next);
+}
+
+static void zen_add_request(struct request_queue *q, struct request *rq)
+{
+ struct zen_data *zdata = zen_get_data(q);
+ const int dir = rq_data_dir(rq);
+
+ if (zdata->fifo_expire[dir]) {
+ rq_set_fifo_time(rq, jiffies + zdata->fifo_expire[dir]);
+ list_add_tail(&rq->queuelist, &zdata->fifo_list[dir]);
+ }
+}
+
+static void zen_dispatch(struct zen_data *zdata, struct request *rq)
+{
+ /* Remove request from list and dispatch it */
+ rq_fifo_clear(rq);
+ elv_dispatch_add_tail(rq->q, rq);
+
+ /* Increment # of sequential requests */
+ zdata->batching++;
+}
+
+/*
+ * get the first expired request in direction ddir
+ */
+static struct request *
+zen_expired_request(struct zen_data *zdata, int ddir)
+{
+ struct request *rq;
+
+ if (list_empty(&zdata->fifo_list[ddir]))
+ return NULL;
+
+ rq = rq_entry_fifo(zdata->fifo_list[ddir].next);
+ if (time_after(jiffies, rq_fifo_time(rq)))
+ return rq;
+
+ return NULL;
+}
+
+/*
+ * zen_check_fifo returns 0 if there are no expired requests on the fifo,
+ * otherwise it returns the next expired request
+ */
+static struct request *
+zen_check_fifo(struct zen_data *zdata)
+{
+ struct request *rq_sync = zen_expired_request(zdata, SYNC);
+ struct request *rq_async = zen_expired_request(zdata, ASYNC);
+
+ if (rq_async && rq_sync) {
+ if (time_after(rq_fifo_time(rq_async), rq_fifo_time(rq_sync)))
+ return rq_sync;
+ } else if (rq_sync) {
+ return rq_sync;
+ } else if (rq_async) {
+ return rq_async;
+ }
+
+ return 0;
+}
+
+static struct request *
+zen_choose_request(struct zen_data *zdata)
+{
+ /*
+ * Retrieve request from available fifo list.
+ * Synchronous requests have priority over asynchronous.
+ */
+ if (!list_empty(&zdata->fifo_list[SYNC]))
+ return rq_entry_fifo(zdata->fifo_list[SYNC].next);
+ if (!list_empty(&zdata->fifo_list[ASYNC]))
+ return rq_entry_fifo(zdata->fifo_list[ASYNC].next);
+
+ return NULL;
+}
+
+static int zen_dispatch_requests(struct request_queue *q, int force)
+{
+ struct zen_data *zdata = zen_get_data(q);
+ struct request *rq = NULL;
+
+ /* Check for and issue expired requests */
+ if (zdata->batching > zdata->fifo_batch) {
+ zdata->batching = 0;
+ rq = zen_check_fifo(zdata);
+ }
+
+ if (!rq) {
+ rq = zen_choose_request(zdata);
+ if (!rq)
+ return 0;
+ }
+
+ zen_dispatch(zdata, rq);
+
+ return 1;
+}
+
+static void *zen_init_queue(struct request_queue *q)
+{
+ struct zen_data *zdata;
+
+ zdata = kmalloc_node(sizeof(*zdata), GFP_KERNEL, q->node);
+ if (!zdata)
+ return NULL;
+ INIT_LIST_HEAD(&zdata->fifo_list[SYNC]);
+ INIT_LIST_HEAD(&zdata->fifo_list[ASYNC]);
+ zdata->fifo_expire[SYNC] = sync_expire;
+ zdata->fifo_expire[ASYNC] = async_expire;
+ zdata->fifo_batch = fifo_batch;
+ return zdata;
+}
+
+static void zen_exit_queue(struct elevator_queue *e)
+{
+ struct zen_data *zdata = e->elevator_data;
+
+ BUG_ON(!list_empty(&zdata->fifo_list[SYNC]));
+ BUG_ON(!list_empty(&zdata->fifo_list[ASYNC]));
+ kfree(zdata);
+}
+
+/* Sysfs */
+static ssize_t
+zen_var_show(int var, char *page)
+{
+ return sprintf(page, "%d\n", var);
+}
+
+static ssize_t
+zen_var_store(int *var, const char *page, size_t count)
+{
+ *var = simple_strtol(page, NULL, 10);
+ return count;
+}
+
+#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
+static ssize_t __FUNC(struct elevator_queue *e, char *page) \
+{ \
+ struct zen_data *zdata = e->elevator_data; \
+ int __data = __VAR; \
+ if (__CONV) \
+ __data = jiffies_to_msecs(__data); \
+ return zen_var_show(__data, (page)); \
+}
+SHOW_FUNCTION(zen_sync_expire_show, zdata->fifo_expire[SYNC], 1);
+SHOW_FUNCTION(zen_async_expire_show, zdata->fifo_expire[ASYNC], 1);
+SHOW_FUNCTION(zen_fifo_batch_show, zdata->fifo_batch, 0);
+#undef SHOW_FUNCTION
+
+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
+static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
+{ \
+ struct zen_data *zdata = e->elevator_data; \
+ int __data; \
+ int ret = zen_var_store(&__data, (page), count); \
+ if (__data < (MIN)) \
+ __data = (MIN); \
+ else if (__data > (MAX)) \
+ __data = (MAX); \
+ if (__CONV) \
+ *(__PTR) = msecs_to_jiffies(__data); \
+ else \
+ *(__PTR) = __data; \
+ return ret; \
+}
+STORE_FUNCTION(zen_sync_expire_store, &zdata->fifo_expire[SYNC], 0, INT_MAX, 1);
+STORE_FUNCTION(zen_async_expire_store, &zdata->fifo_expire[ASYNC], 0, INT_MAX, 1);
+STORE_FUNCTION(zen_fifo_batch_store, &zdata->fifo_batch, 0, INT_MAX, 0);
+#undef STORE_FUNCTION
+
+#define DD_ATTR(name) \
+ __ATTR(name, S_IRUGO|S_IWUSR, zen_##name##_show, \
+ zen_##name##_store)
+
+static struct elv_fs_entry zen_attrs[] = {
+ DD_ATTR(sync_expire),
+ DD_ATTR(async_expire),
+ DD_ATTR(fifo_batch),
+ __ATTR_NULL
+};
+
+static struct elevator_type iosched_zen = {
+ .ops = {
+ .elevator_merge_req_fn = zen_merged_requests,
+ .elevator_dispatch_fn = zen_dispatch_requests,
+ .elevator_add_req_fn = zen_add_request,
+ .elevator_former_req_fn = elv_rb_former_request,
+ .elevator_latter_req_fn = elv_rb_latter_request,
+ .elevator_init_fn = zen_init_queue,
+ .elevator_exit_fn = zen_exit_queue,
+ },
+ .elevator_attrs = zen_attrs,
+ .elevator_name = "zen",
+ .elevator_owner = THIS_MODULE,
+};
+
+static int __init zen_init(void)
+{
+ elv_register(&iosched_zen);
+
+ return 0;
+}
+
+static void __exit zen_exit(void)
+{
+ elv_unregister(&iosched_zen);
+}
+
+module_init(zen_init);
+module_exit(zen_exit);
+
+
+MODULE_AUTHOR("Brandon Berhent");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Zen IO scheduler");
+MODULE_VERSION("1.0");
--- /dev/null
+++ b/include/linux/slide2wake.h
@@ -0,0 +1,5 @@
+extern void slide2wake_setdev(struct input_dev *input_device);
+extern void slide2wake_change(unsigned int val);
+extern bool s2w_enabled;
+extern bool s2w_enabled_plug;
+extern bool s2w_prox_near;
projects / ziggy471-sgs3-jb.git / commitdiff