The patch titled
Subject: fs/proc/array.c: slightly improve render_sigset_t
has been added to the -mm tree. Its filename is
fs-proc-arrayc-slightly-improve-render_sigset_t.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fs-proc-arrayc-slightly-improve-render_sigset_t.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fs-proc-arrayc-slightly-improve-render_sigset_t.patch
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------------------------------------------------------
From: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Subject: fs/proc/array.c: slightly improve render_sigset_t
format_decode and vsnprintf occasionally show up in perf top, so I went
looking for places that might not need the full printf power. With the
help of kprobes, I gathered some statistics on which format strings we
mostly pass to vsnprintf. On a trivial desktop workload, I hit "%x" 25%
of the time, so something apparently reads /proc/pid/status (which does
5*16 printf("%x") calls) a lot.
With this patch, reading /proc/pid/status is 30% faster according to
this microbenchmark:
char buf[4096];
int i, fd;
for (i = 0; i < 10000; ++i) {
fd = open("/proc/self/status", O_RDONLY);
read(fd, buf, sizeof(buf));
close(fd);
}
Link: http://lkml.kernel.org/r/1474410485-1305-1-git-send-email-linux@xxxxxxxxxxxxxxxxxx
Signed-off-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/array.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN fs/proc/array.c~fs-proc-arrayc-slightly-improve-render_sigset_t fs/proc/array.c
--- a/fs/proc/array.c~fs-proc-arrayc-slightly-improve-render_sigset_t
+++ a/fs/proc/array.c
@@ -245,7 +245,7 @@ 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);
+ seq_putc(m, hex_asc[x]);
} while (i >= 4);
seq_putc(m, '\n');
_
Patches currently in -mm which might be from linux@xxxxxxxxxxxxxxxxxx are
fs-proc-arrayc-slightly-improve-render_sigset_t.patch
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