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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2012-03-23 15:02:53 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-03-23 16:58:42 -0700 |
| commit | 59a32e2ce5eb809967cac4e718bc527beca83c59 (patch) | |
| tree | 3024b71063f497c138680c36c5f7ce2dee563680 | |
| parent | b908243c549448fc0662f9cdd8d5cfe620fcdc31 (diff) | |
| download | linux-59a32e2ce5eb809967cac4e718bc527beca83c59.tar.bz2 | |
proc: speed up /proc/stat handling
On a typical 16 cpus machine, "cat /proc/stat" gives more than 4096 bytes,
and is slow :
# strace -T -o /tmp/STRACE cat /proc/stat | wc -c
5826
# grep "cpu " /tmp/STRACE
read(0, "cpu 1949310 19 2144714 12117253"..., 32768) = 5826 <0.001504>
Thats partly because show_stat() must be called twice since initial
buffer size is too small (4096 bytes for less than 32 possible cpus)
Fix this by :
1) Taking into account nr_irqs in the initial buffer sizing.
2) Using ksize() to allow better filling of initial buffer.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/proc/stat.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/fs/proc/stat.c b/fs/proc/stat.c index 121f77cfef76..ac446114cd48 100644 --- a/fs/proc/stat.c +++ b/fs/proc/stat.c @@ -157,11 +157,14 @@ static int show_stat(struct seq_file *p, void *v) static int stat_open(struct inode *inode, struct file *file) { - unsigned size = 4096 * (1 + num_possible_cpus() / 32); + unsigned size = 1024 + 128 * num_possible_cpus(); char *buf; struct seq_file *m; int res; + /* minimum size to display an interrupt count : 2 bytes */ + size += 2 * nr_irqs; + /* don't ask for more than the kmalloc() max size */ if (size > KMALLOC_MAX_SIZE) size = KMALLOC_MAX_SIZE; @@ -173,7 +176,7 @@ static int stat_open(struct inode *inode, struct file *file) if (!res) { m = file->private_data; m->buf = buf; - m->size = size; + m->size = ksize(buf); } else kfree(buf); return res; |