--- mm/filemap.c
+++ mm/filemap.c
@@ -454,8 +454,8 @@ out:
}
EXPORT_SYMBOL(add_to_page_cache_locked);
-int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
- pgoff_t offset, gfp_t gfp_mask)
+int __add_to_page_cache_lru(struct page *page, struct address_space *mapping,
+ pgoff_t offset, gfp_t gfp_mask, int tail)
{
int ret;
@@ -471,12 +471,19 @@ int add_to_page_cache_lru(struct page *p
ret = add_to_page_cache(page, mapping, offset, gfp_mask);
if (ret == 0) {
if (page_is_file_cache(page))
- lru_cache_add_file(page);
+ lru_cache_add_file(page, tail);
else
lru_cache_add_anon(page);
}
return ret;
}
+
+int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
+ pgoff_t offset, gfp_t gfp_mask)
+{
+ return __add_to_page_cache_lru(page, mapping, offset, gfp_mask, 0);
+}
+
EXPORT_SYMBOL_GPL(add_to_page_cache_lru);
#ifdef CONFIG_NUMA
@@ -970,6 +977,28 @@ static void shrink_readahead_size_eio(st
ra->ra_pages /= 4;
}
+static inline int nr_mapped(void)
+{
+ return global_page_state(NR_FILE_MAPPED) +
+ global_page_state(NR_ANON_PAGES);
+}
+
+/*
+ * This examines how large in pages a file size is and returns 1 if it is
+ * more than half the unmapped ram. Avoid doing read_page_state which is
+ * expensive unless we already know it is likely to be large enough.
+ */
+static int large_isize(unsigned long nr_pages)
+{
+ if (nr_pages * 6 > vm_total_pages) {
+ unsigned long unmapped_ram = vm_total_pages - nr_mapped();
+
+ if (nr_pages * 2 > unmapped_ram)
+ return 1;
+ }
+ return 0;
+}
+
/**
* do_generic_file_read - generic file read routine
* @filp: the file to read
@@ -994,7 +1023,7 @@ static void do_generic_file_read(struct
pgoff_t prev_index;
unsigned long offset; /* offset into pagecache page */
unsigned int prev_offset;
- int error;
+ int error, tail = 0;
index = *ppos >> PAGE_CACHE_SHIFT;
prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
@@ -1005,7 +1034,7 @@ static void do_generic_file_read(struct
for (;;) {
struct page *page;
pgoff_t end_index;
- loff_t isize;
+ loff_t isize = 0;
unsigned long nr, ret;
cond_resched();
@@ -1179,8 +1208,16 @@ no_cached_page:
desc->error = -ENOMEM;
goto out;
}
- error = add_to_page_cache_lru(page, mapping,
- index, GFP_KERNEL);
+ /*
+ * If we know the file is large we add the pages read to the
+ * end of the lru as we're unlikely to be able to cache the
+ * whole file in ram so make those pages the first to be
+ * dropped if not referenced soon.
+ */
+ if (large_isize(end_index))
+ tail = 1;
+ error = __add_to_page_cache_lru(page, mapping,
+ index, GFP_KERNEL, tail);
if (error) {
page_cache_release(page);
if (error == -EEXIST)
projects / ziggy471-frankenstein-kernel.git / blobdiff