diff options
| author | Andrei Vagin <avagin@openvz.org> | 2018-04-11 02:31:23 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-04-11 20:28:33 +0300 |
| commit | 48dffbf82d2f17bc6dd3c2b7fd733738ea567914 (patch) | |
| tree | 40e7facfdd53bd3157622b9a03d61802b684319f /fs | |
| parent | f66406638fffe874c56e7e41106167c5235f251e (diff) | |
| download | linux-48dffbf82d2f17bc6dd3c2b7fd733738ea567914.tar.xz | |
proc: optimize single-symbol delimiters to spead up seq_put_decimal_ull
A delimiter is a string which is printed before a number. A
syngle-symbol delimiters can be printed by set_putc() and this works
faster than printing by set_puts().
== test_proc.c
int main(int argc, char **argv)
{
int n, i, fd;
char buf[16384];
n = atoi(argv[1]);
for (i = 0; i < n; i++) {
fd = open(argv[2], O_RDONLY);
if (fd < 0)
return 1;
if (read(fd, buf, sizeof(buf)) <= 0)
return 1;
close(fd);
}
return 0;
}
==
$ time ./test_proc 1000000 /proc/1/stat
== Before patch ==
real 0m3.820s
user 0m0.337s
sys 0m3.394s
== After patch ==
real 0m3.110s
user 0m0.324s
sys 0m2.700s
Link: http://lkml.kernel.org/r/20180212074931.7227-3-avagin@openvz.org
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
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/seq_file.c | 24 |
1 files changed, 12 insertions, 12 deletions
diff --git a/fs/seq_file.c b/fs/seq_file.c index 84650ad3b1bf..0677e89f3c6f 100644 --- a/fs/seq_file.c +++ b/fs/seq_file.c @@ -693,12 +693,12 @@ void seq_put_decimal_ull_width(struct seq_file *m, const char *delimiter, if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */ goto overflow; - len = strlen(delimiter); - if (m->count + len >= m->size) - goto overflow; - - memcpy(m->buf + m->count, delimiter, len); - m->count += len; + if (delimiter && delimiter[0]) { + if (delimiter[1] == 0) + seq_putc(m, delimiter[0]); + else + seq_puts(m, delimiter); + } if (!width) width = 1; @@ -782,12 +782,12 @@ void seq_put_decimal_ll(struct seq_file *m, const char *delimiter, long long num if (m->count + 3 >= m->size) /* we'll write 2 bytes at least */ goto overflow; - len = strlen(delimiter); - if (m->count + len >= m->size) - goto overflow; - - memcpy(m->buf + m->count, delimiter, len); - m->count += len; + if (delimiter && delimiter[0]) { + if (delimiter[1] == 0) + seq_putc(m, delimiter[0]); + else + seq_puts(m, delimiter); + } if (m->count + 2 >= m->size) goto overflow; |