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authorAndrei Vagin <avagin@openvz.org>2018-04-10 16:31:23 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-11 10:28:33 -0700
commit48dffbf82d2f17bc6dd3c2b7fd733738ea567914 (patch)
tree40e7facfdd53bd3157622b9a03d61802b684319f /fs/seq_file.c
parentf66406638fffe874c56e7e41106167c5235f251e (diff)
downloadlinux-stericsson-48dffbf82d2f17bc6dd3c2b7fd733738ea567914.tar.gz
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/seq_file.c')
-rw-r--r--fs/seq_file.c24
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;