The patch titled
Subject: fs/proc/array.c: optimize render_sigset_t()
has been added to the -mm tree. Its filename is
proc-optimize-render_sigset_t.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/proc-optimize-render_sigset_t.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/proc-optimize-render_sigset_t.patch
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------------------------------------------------------
From: Andrei Vagin <avagin@xxxxxxxxxx>
Subject: fs/proc/array.c: optimize render_sigset_t()
render_sigset_t() requires about 30% of time to generate /proc/pid/status.
- 74.44% sys_read
- 74.40% vfs_read
- 74.01% __vfs_read
- 73.36% seq_read
- 72.97% proc_single_show
- 72.26% proc_pid_status
+ 29.79% render_sigset_t
+ 11.47% task_mem
+ 5.60% render_cap_t
+ 4.95% seq_printf
+ 4.28% cpuset_task_status_allowed
seq_printf is called for each symbol of a signal mask. This patch collect
a whole mask in a buffer and prints it for one call of seq_puts().
- 65.02% proc_single_show
- 63.75% proc_pid_status
+ 15.73% task_mem
+ 7.42% render_sigset_t
+ 7.39% render_cap_t
+ 6.46% cpuset_task_status_allowed
/proc/pid/status is generated 25% faster with this optimization.
Link: http://lkml.kernel.org/r/1478641048-11406-1-git-send-email-avagin@xxxxxxxxxx
Signed-off-by: Andrei Vagin <avagin@xxxxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/array.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff -puN fs/proc/array.c~proc-optimize-render_sigset_t fs/proc/array.c
--- a/fs/proc/array.c~proc-optimize-render_sigset_t
+++ a/fs/proc/array.c
@@ -232,11 +232,13 @@ static inline void task_state(struct seq
void render_sigset_t(struct seq_file *m, const char *header,
sigset_t *set)
{
- int i;
+ char buf[_NSIG / 4 + 2];
+ int i, j;
seq_puts(m, header);
i = _NSIG;
+ j = 0;
do {
int x = 0;
@@ -245,10 +247,13 @@ void render_sigset_t(struct seq_file *m,
if (sigismember(set, i+2)) x |= 2;
if (sigismember(set, i+3)) x |= 4;
if (sigismember(set, i+4)) x |= 8;
- seq_printf(m, "%x", x);
+ buf[j++] = hex_asc[x];
} while (i >= 4);
- seq_putc(m, '\n');
+ buf[j++] = '\n';
+ buf[j++] = 0;
+
+ seq_puts(m, buf);
}
static void collect_sigign_sigcatch(struct task_struct *p, sigset_t *ign,
_
Patches currently in -mm which might be from avagin@xxxxxxxxxx are
proc-optimize-render_sigset_t.patch
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