Messages in this thread Patch in this message | | | From | Andrei Vagin <> | Subject | [PATCH] proc: optimize render_sigset_t() | Date | Tue, 8 Nov 2016 13:37:28 -0800 |
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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.
Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrei Vagin <avagin@openvz.org> --- fs/proc/array.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/fs/proc/array.c b/fs/proc/array.c index 81818ad..0190c3e 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -232,11 +232,13 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, 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, const char *header, 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, -- 2.7.4
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