PROCFS: add num_to_str() to speed up /proc/stat

file:9758b654a1bcffe27c414ef322f34cd6a8658c33 -> file:cb50cb279c6cce7194ab330c23e1c0d84883b993
--- a/fs/proc/stat.c
+++ b/fs/proc/stat.c
@@ -63,18 +63,19 @@ static int show_stat(struct seq_file *p,
}
sum += arch_irq_stat();
- seq_printf(p, "cpu %llu %llu %llu %llu %llu %llu %llu %llu %llu "
- "%llu\n",
- (unsigned long long)cputime64_to_clock_t(user),
- (unsigned long long)cputime64_to_clock_t(nice),
- (unsigned long long)cputime64_to_clock_t(system),
- (unsigned long long)cputime64_to_clock_t(idle),
- (unsigned long long)cputime64_to_clock_t(iowait),
- (unsigned long long)cputime64_to_clock_t(irq),
- (unsigned long long)cputime64_to_clock_t(softirq),
- (unsigned long long)cputime64_to_clock_t(steal),
- (unsigned long long)cputime64_to_clock_t(guest),
- (unsigned long long)cputime64_to_clock_t(guest_nice));
+ seq_puts(p, "cpu ");
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(user));
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(nice));
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(system));
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(idle));
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(iowait));
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(irq));
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(softirq));
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(steal));
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(guest));
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(guest_nice));
+ seq_putc(p, '\n');
+
for_each_online_cpu(i) {
/* Copy values here to work around gcc-2.95.3, gcc-2.96 */
@@ -89,26 +90,24 @@ static int show_stat(struct seq_file *p,
steal = kstat_cpu(i).cpustat.steal;
guest = kstat_cpu(i).cpustat.guest;
guest_nice = kstat_cpu(i).cpustat.guest_nice;
- seq_printf(p,
- "cpu%d %llu %llu %llu %llu %llu %llu %llu %llu %llu "
- "%llu\n",
- i,
- (unsigned long long)cputime64_to_clock_t(user),
- (unsigned long long)cputime64_to_clock_t(nice),
- (unsigned long long)cputime64_to_clock_t(system),
- (unsigned long long)cputime64_to_clock_t(idle),
- (unsigned long long)cputime64_to_clock_t(iowait),
- (unsigned long long)cputime64_to_clock_t(irq),
- (unsigned long long)cputime64_to_clock_t(softirq),
- (unsigned long long)cputime64_to_clock_t(steal),
- (unsigned long long)cputime64_to_clock_t(guest),
- (unsigned long long)cputime64_to_clock_t(guest_nice));
+ seq_printf(p, "cpu%d", i);
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(user));
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(nice));
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(system));
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(idle));
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(iowait));
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(irq));
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(softirq));
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(steal));
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(guest));
+ seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(guest_nice));
+ seq_putc(p, '\n');
}
seq_printf(p, "intr %llu", (unsigned long long)sum);
/* sum again ? it could be updated? */
for_each_irq_nr(j)
- seq_printf(p, " %u", kstat_irqs(j));
+ seq_put_decimal_ull(p, ' ', kstat_irqs(j));
seq_printf(p,
"\nctxt %llu\n"
@@ -125,7 +124,7 @@ static int show_stat(struct seq_file *p,
seq_printf(p, "softirq %llu", (unsigned long long)sum_softirq);
for (i = 0; i < NR_SOFTIRQS; i++)
- seq_printf(p, " %u", per_softirq_sums[i]);
+ seq_put_decimal_ull(p, ' ', per_softirq_sums[i]);
seq_putc(p, '\n');
return 0;
file:dba43c3ea3afb6605972d3a0e3eca3ac5248876e -> file:461032a00240b76849b96277cfdda77d61da558a
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -642,6 +642,39 @@ int seq_puts(struct seq_file *m, const c
}
EXPORT_SYMBOL(seq_puts);
+/*
+ * A helper routine for putting decimal numbers without rich format of printf().
+ * only 'unsigned long long' is supported.
+ * This routine will put one byte delimiter + number into seq_file.
+ * This routine is very quick when you show lots of numbers.
+ * In usual cases, it will be better to use seq_printf(). It's easier to read.
+ */
+int seq_put_decimal_ull(struct seq_file *m, char delimiter,
+ unsigned long long num)
+{
+ int len;
+
+ if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */
+ goto overflow;
+
+ m->buf[m->count++] = delimiter;
+
+ if (num < 10) {
+ m->buf[m->count++] = num + '0';
+ return 0;
+ }
+
+ len = num_to_str(m->buf + m->count, m->size - m->count, num);
+ if (!len)
+ goto overflow;
+ m->count += len;
+ return 0;
+overflow:
+ m->count = m->size;
+ return -1;
+}
+EXPORT_SYMBOL(seq_put_decimal_ull);
+
/**
* seq_write - write arbitrary data to buffer
* @seq: seq_file identifying the buffer to which data should be written
file:4ae54e07de83d2b970d88807f662bcfe300f2ddc -> file:a7b0914348fd0fce08ed7cb42bbe2c8fbacbf8f9
--- a/include/asm-generic/bitsperlong.h
+++ b/include/asm-generic/bitsperlong.h
@@ -28,5 +28,9 @@
#error Inconsistent word size. Check asm/bitsperlong.h
#endif
+#ifndef BITS_PER_LONG_LONG
+#define BITS_PER_LONG_LONG 64
+#endif
+
#endif /* __KERNEL__ */
#endif /* __ASM_GENERIC_BITS_PER_LONG */
file:03c0232b4169dfccf378be1420fdcec29b9c134b -> file:0ca31f888d8869995c7ff0b50109a10f97e6454d
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -121,9 +121,10 @@ int single_release(struct inode *, struc
void *__seq_open_private(struct file *, const struct seq_operations *, int);
int seq_open_private(struct file *, const struct seq_operations *, int);
int seq_release_private(struct inode *, struct file *);
+int seq_put_decimal_ull(struct seq_file *m, char delimiter,
+ unsigned long long num);
#define SEQ_START_TOKEN ((void *)1)
-
/*
* Helpers for iteration over list_head-s in seq_files
*/
file:4365df31a1d52122cd670d5ad2fe321fc887337f -> file:24d7bc8da7fedcdfcb68d5f007f1210530eb6ce5
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -134,104 +134,214 @@ int skip_atoi(const char **s)
/* Decimal conversion is by far the most typical, and is used
* for /proc and /sys data. This directly impacts e.g. top performance
* with many processes running. We optimize it for speed
- * using code from
- * http://www.cs.uiowa.edu/~jones/bcd/decimal.html
- * (with permission from the author, Douglas W. Jones). */
-
-/* Formats correctly any integer in [0,99999].
- * Outputs from one to five digits depending on input.
- * On i386 gcc 4.1.2 -O2: ~250 bytes of code. */
+ * using ideas described at <http://www.cs.uiowa.edu/~jones/bcd/divide.html>
+ * (with permission from the author, Douglas W. Jones).
+ */
+
+#if BITS_PER_LONG != 32 || BITS_PER_LONG_LONG != 64
+/* Formats correctly any integer in [0, 999999999] */
static noinline_for_stack
-char *put_dec_trunc(char *buf, unsigned q)
+char *put_dec_full9(char *buf, unsigned q)
{
- unsigned d3, d2, d1, d0;
- d1 = (q>>4) & 0xf;
- d2 = (q>>8) & 0xf;
- d3 = (q>>12);
-
- d0 = 6*(d3 + d2 + d1) + (q & 0xf);
- q = (d0 * 0xcd) >> 11;
- d0 = d0 - 10*q;
- *buf++ = d0 + '0'; /* least significant digit */
- d1 = q + 9*d3 + 5*d2 + d1;
- if (d1 != 0) {
- q = (d1 * 0xcd) >> 11;
- d1 = d1 - 10*q;
- *buf++ = d1 + '0'; /* next digit */
-
- d2 = q + 2*d2;
- if ((d2 != 0) || (d3 != 0)) {
- q = (d2 * 0xd) >> 7;
- d2 = d2 - 10*q;
- *buf++ = d2 + '0'; /* next digit */
-
- d3 = q + 4*d3;
- if (d3 != 0) {
- q = (d3 * 0xcd) >> 11;
- d3 = d3 - 10*q;
- *buf++ = d3 + '0'; /* next digit */
- if (q != 0)
- *buf++ = q + '0'; /* most sign. digit */
- }
- }
- }
+ unsigned r;
+ /* Possible ways to approx. divide by 10
+ * (x * 0x1999999a) >> 32 x < 1073741829 (multiply must be 64-bit)
+ * (x * 0xcccd) >> 19 x < 81920 (x < 262149 when 64-bit mul)
+ * (x * 0x6667) >> 18 x < 43699
+ * (x * 0x3334) >> 17 x < 16389
+ * (x * 0x199a) >> 16 x < 16389
+ * (x * 0x0ccd) >> 15 x < 16389
+ * (x * 0x0667) >> 14 x < 2739
+ * (x * 0x0334) >> 13 x < 1029
+ * (x * 0x019a) >> 12 x < 1029
+ * (x * 0x00cd) >> 11 x < 1029 shorter code than * 0x67 (on i386)
+ * (x * 0x0067) >> 10 x < 179
+ * (x * 0x0034) >> 9 x < 69 same
+ * (x * 0x001a) >> 8 x < 69 same
+ * (x * 0x000d) >> 7 x < 69 same, shortest code (on i386)
+ * (x * 0x0007) >> 6 x < 19
+ * See <http://www.cs.uiowa.edu/~jones/bcd/divide.html>
+ */
+ r = (q * (uint64_t)0x1999999a) >> 32;
+ *buf++ = (q - 10 * r) + '0'; /* 1 */
+ q = (r * (uint64_t)0x1999999a) >> 32;
+ *buf++ = (r - 10 * q) + '0'; /* 2 */
+ r = (q * (uint64_t)0x1999999a) >> 32;
+ *buf++ = (q - 10 * r) + '0'; /* 3 */
+ q = (r * (uint64_t)0x1999999a) >> 32;
+ *buf++ = (r - 10 * q) + '0'; /* 4 */
+ r = (q * (uint64_t)0x1999999a) >> 32;
+ *buf++ = (q - 10 * r) + '0'; /* 5 */
+ /* Now value is under 10000, can avoid 64-bit multiply */
+ q = (r * 0x199a) >> 16;
+ *buf++ = (r - 10 * q) + '0'; /* 6 */
+ r = (q * 0xcd) >> 11;
+ *buf++ = (q - 10 * r) + '0'; /* 7 */
+ q = (r * 0xcd) >> 11;
+ *buf++ = (r - 10 * q) + '0'; /* 8 */
+ *buf++ = q + '0'; /* 9 */
return buf;
}
-/* Same with if's removed. Always emits five digits */
+#endif
+
+/* Similar to above but do not pad with zeros.
+ * Code can be easily arranged to print 9 digits too, but our callers
+ * always call put_dec_full9() instead when the number has 9 decimal digits.
+ */
static noinline_for_stack
-char *put_dec_full(char *buf, unsigned q)
+char *put_dec_trunc8(char *buf, unsigned r)
{
- /* BTW, if q is in [0,9999], 8-bit ints will be enough, */
- /* but anyway, gcc produces better code with full-sized ints */
- unsigned d3, d2, d1, d0;
- d1 = (q>>4) & 0xf;
- d2 = (q>>8) & 0xf;
- d3 = (q>>12);
-
- /*
- * Possible ways to approx. divide by 10
- * gcc -O2 replaces multiply with shifts and adds
- * (x * 0xcd) >> 11: 11001101 - shorter code than * 0x67 (on i386)
- * (x * 0x67) >> 10: 1100111
- * (x * 0x34) >> 9: 110100 - same
- * (x * 0x1a) >> 8: 11010 - same
- * (x * 0x0d) >> 7: 1101 - same, shortest code (on i386)
- */
- d0 = 6*(d3 + d2 + d1) + (q & 0xf);
- q = (d0 * 0xcd) >> 11;
- d0 = d0 - 10*q;
- *buf++ = d0 + '0';
- d1 = q + 9*d3 + 5*d2 + d1;
- q = (d1 * 0xcd) >> 11;
- d1 = d1 - 10*q;
- *buf++ = d1 + '0';
-
- d2 = q + 2*d2;
- q = (d2 * 0xd) >> 7;
- d2 = d2 - 10*q;
- *buf++ = d2 + '0';
-
- d3 = q + 4*d3;
- q = (d3 * 0xcd) >> 11; /* - shorter code */
- /* q = (d3 * 0x67) >> 10; - would also work */
- d3 = d3 - 10*q;
- *buf++ = d3 + '0';
- *buf++ = q + '0';
+ unsigned q;
+ /* Copy of previous function's body with added early returns */
+ q = (r * (uint64_t)0x1999999a) >> 32;
+ *buf++ = (r - 10 * q) + '0'; /* 2 */
+ if (q == 0) return buf;
+ r = (q * (uint64_t)0x1999999a) >> 32;
+ *buf++ = (q - 10 * r) + '0'; /* 3 */
+ if (r == 0) return buf;
+ q = (r * (uint64_t)0x1999999a) >> 32;
+ *buf++ = (r - 10 * q) + '0'; /* 4 */
+ if (q == 0) return buf;
+ r = (q * (uint64_t)0x1999999a) >> 32;
+ *buf++ = (q - 10 * r) + '0'; /* 5 */
+ if (r == 0) return buf;
+ q = (r * 0x199a) >> 16;
+ *buf++ = (r - 10 * q) + '0'; /* 6 */
+ if (q == 0) return buf;
+ r = (q * 0xcd) >> 11;
+ *buf++ = (q - 10 * r) + '0'; /* 7 */
+ if (r == 0) return buf;
+ q = (r * 0xcd) >> 11;
+ *buf++ = (r - 10 * q) + '0'; /* 8 */
+ if (q == 0) return buf;
+ *buf++ = q + '0'; /* 9 */
return buf;
}
-/* No inlining helps gcc to use registers better */
+/* There are two algorithms to print larger numbers.
+ * One is generic: divide by 1000000000 and repeatedly print
+ * groups of (up to) 9 digits. It's conceptually simple,
+ * but requires a (unsigned long long) / 1000000000 division.
+ *
+ * Second algorithm splits 64-bit unsigned long long into 16-bit chunks,
+ * manipulates them cleverly and generates groups of 4 decimal digits.
+ * It so happens that it does NOT require long long division.
+ *
+ * If long is > 32 bits, division of 64-bit values is relatively easy,
+ * and we will use the first algorithm.
+ * If long long is > 64 bits (strange architecture with VERY large long long),
+ * second algorithm can't be used, and we again use the first one.
+ *
+ * Else (if long is 32 bits and long long is 64 bits) we use second one.
+ */
+
+#if BITS_PER_LONG != 32 || BITS_PER_LONG_LONG != 64
+
+/* First algorithm: generic */
+
+static
+char *put_dec(char *buf, unsigned long long n)
+{
+ if (n >= 100*1000*1000) {
+ while (n >= 1000*1000*1000)
+ buf = put_dec_full9(buf, do_div(n, 1000*1000*1000));
+ if (n >= 100*1000*1000)
+ return put_dec_full9(buf, n);
+ }
+ return put_dec_trunc8(buf, n);
+}
+
+#else
+
+/* Second algorithm: valid only for 64-bit long longs */
+
static noinline_for_stack
-char *put_dec(char *buf, unsigned long long num)
+char *put_dec_full4(char *buf, unsigned q)
{
- while (1) {
- unsigned rem;
- if (num < 100000)
- return put_dec_trunc(buf, num);
- rem = do_div(num, 100000);
- buf = put_dec_full(buf, rem);
+ unsigned r;
+ r = (q * 0xcccd) >> 19;
+ *buf++ = (q - 10 * r) + '0';
+ q = (r * 0x199a) >> 16;
+ *buf++ = (r - 10 * q) + '0';
+ r = (q * 0xcd) >> 11;
+ *buf++ = (q - 10 * r) + '0';
+ *buf++ = r + '0';
+ return buf;
+}
+
+/* Based on code by Douglas W. Jones found at
+ * <http://www.cs.uiowa.edu/~jones/bcd/decimal.html#sixtyfour>
+ * (with permission from the author).
+ * Performs no 64-bit division and hence should be fast on 32-bit machines.
+ */
+static
+char *put_dec(char *buf, unsigned long long n)
+{
+ uint32_t d3, d2, d1, q, h;
+
+ if (n < 100*1000*1000)
+ return put_dec_trunc8(buf, n);
+
+ d1 = ((uint32_t)n >> 16); /* implicit "& 0xffff" */
+ h = (n >> 32);
+ d2 = (h ) & 0xffff;
+ d3 = (h >> 16); /* implicit "& 0xffff" */
+
+ q = 656 * d3 + 7296 * d2 + 5536 * d1 + ((uint32_t)n & 0xffff);
+
+ buf = put_dec_full4(buf, q % 10000);
+ q = q / 10000;
+
+ d1 = q + 7671 * d3 + 9496 * d2 + 6 * d1;
+ buf = put_dec_full4(buf, d1 % 10000);
+ q = d1 / 10000;
+
+ d2 = q + 4749 * d3 + 42 * d2;
+ buf = put_dec_full4(buf, d2 % 10000);
+ q = d2 / 10000;
+
+ d3 = q + 281 * d3;
+ if (!d3)
+ goto done;
+ buf = put_dec_full4(buf, d3 % 10000);
+ q = d3 / 10000;
+ if (!q)
+ goto done;
+ buf = put_dec_full4(buf, q);
+done:
+ while (buf[-1] == '0')
+ --buf;
+
+ return buf;
+}
+
+#endif
+
+/*
+ * Convert passed number to decimal string.
+ * Returns the length of string. On buffer overflow, returns 0.
+ *
+ * If speed is not important, use snprintf(). It's easy to read the code.
+ */
+int num_to_str(char *buf, int size, unsigned long long num)
+{
+ char tmp[sizeof(num) * 3];
+ int idx, len;
+
+ /* put_dec() may work incorrectly for num = 0 (generate "", not "0") */
+ if (num <= 9) {
+ tmp[0] = '0' + num;
+ len = 1;
+ } else {
+ len = put_dec(tmp, num) - tmp;
}
+
+ if (len > size)
+ return 0;
+ for (idx = 0; idx < len; ++idx)
+ buf[idx] = tmp[len - idx - 1];
+ return len;
}
#define ZEROPAD 1 /* pad with zero */
@@ -314,8 +424,8 @@ char *number(char *buf, char *end, unsig
/* generate full string in tmp[], in reverse order */
i = 0;
- if (num == 0)
- tmp[i++] = '0';
+ if (num < spec.base)
+ tmp[i++] = digits[num] | locase;
/* Generic code, for any base:
else do {
tmp[i++] = (digits[do_div(num,base)] | locase);
@@ -609,7 +719,7 @@ char *ip4_string(char *p, const u8 *addr
}
for (i = 0; i < 4; i++) {
char temp[3]; /* hold each IP quad in reverse order */
- int digits = put_dec_trunc(temp, addr[index]) - temp;
+ int digits = put_dec_trunc8(temp, addr[index]) - temp;
if (leading_zeros) {
if (digits < 3)
*p++ = '0';