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authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>2012-03-23 15:02:54 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-23 16:58:42 -0700
commit1ac101a5d675aca2426c5cd460c73fb95acb8391 (patch)
tree5d993fde0c5e67de97c0d9ffac54163f06fc90c9 /fs
parent59a32e2ce5eb809967cac4e718bc527beca83c59 (diff)
procfs: add num_to_str() to speed up /proc/stat
== stat_check.py num = 0 with open("/proc/stat") as f: while num < 1000 : data = f.read() f.seek(0, 0) num = num + 1 == perf shows 20.39% stat_check.py [kernel.kallsyms] [k] format_decode 13.41% stat_check.py [kernel.kallsyms] [k] number 12.61% stat_check.py [kernel.kallsyms] [k] vsnprintf 10.85% stat_check.py [kernel.kallsyms] [k] memcpy 4.85% stat_check.py [kernel.kallsyms] [k] radix_tree_lookup 4.43% stat_check.py [kernel.kallsyms] [k] seq_printf This patch removes most of calls to vsnprintf() by adding num_to_str() and seq_print_decimal_ull(), which prints decimal numbers without rich functions provided by printf(). On my 8cpu box. == Before patch == [root@bluextal test]# time ./stat_check.py real 0m0.150s user 0m0.026s sys 0m0.121s == After patch == [root@bluextal test]# time ./stat_check.py real 0m0.055s user 0m0.022s sys 0m0.030s [akpm@linux-foundation.org: remove incorrect comment, use less statck in num_to_str(), move comment from .h to .c, simplify seq_put_decimal_ull()] [andrea@betterlinux.com: avoid breaking the ABI in /proc/stat] Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrea Righi <andrea@betterlinux.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Glauber Costa <glommer@parallels.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@elte.hu> Cc: Paul Turner <pjt@google.com> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/proc/stat.c55
-rw-r--r--fs/seq_file.c33
2 files changed, 60 insertions, 28 deletions
diff --git a/fs/proc/stat.c b/fs/proc/stat.c
index ac446114cd48..6a0c62d6e442 100644
--- a/fs/proc/stat.c
+++ b/fs/proc/stat.c
@@ -89,18 +89,19 @@ static int show_stat(struct seq_file *p, void *v)
}
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 */
user = kcpustat_cpu(i).cpustat[CPUTIME_USER];
@@ -113,26 +114,24 @@ static int show_stat(struct seq_file *p, void *v)
steal = kcpustat_cpu(i).cpustat[CPUTIME_STEAL];
guest = kcpustat_cpu(i).cpustat[CPUTIME_GUEST];
guest_nice = kcpustat_cpu(i).cpustat[CPUTIME_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"
@@ -149,7 +148,7 @@ static int show_stat(struct seq_file *p, void *v)
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;
diff --git a/fs/seq_file.c b/fs/seq_file.c
index aa242dc99373..7d19816c4cc9 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -644,6 +644,39 @@ int seq_puts(struct seq_file *m, const char *s)
}
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