diff options
| author | Abel Wu <wuyun.wu@huawei.com> | 2020-10-13 16:48:40 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-10-13 18:38:27 -0700 |
| commit | c270cf3041a5cb7c5853d45a794309e66576493a (patch) | |
| tree | 53ec5da29e62574e8b50ce6bd1019c7e02964ad6 /mm/slub.c | |
| parent | d7cff4ded857ff7cc3e49eb39cc14df9345b9662 (diff) | |
mm/slub.c: branch optimization in free slowpath
The two conditions are mutually exclusive and gcc compiler will optimise
this into if-else-like pattern. Given that the majority of free_slowpath
is free_frozen, let's provide some hint to the compilers.
Tests (perf bench sched messaging -g 20 -l 400000, executed 10x
after reboot) are done and the summarized result:
un-patched patched
max. 192.316 189.851
min. 187.267 186.252
avg. 189.154 188.086
stdev. 1.37 0.99
Signed-off-by: Abel Wu <wuyun.wu@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Hewenliang <hewenliang4@huawei.com>
Cc: Hu Shiyuan <hushiyuan@huawei.com>
Link: http://lkml.kernel.org/r/20200813101812.1617-1-wuyun.wu@huawei.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/slub.c')
| -rw-r--r-- | mm/slub.c | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/mm/slub.c b/mm/slub.c index 6d3574013b2f..da6438bd8202 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3019,20 +3019,21 @@ static void __slab_free(struct kmem_cache *s, struct page *page, if (likely(!n)) { - /* - * If we just froze the page then put it onto the - * per cpu partial list. - */ - if (new.frozen && !was_frozen) { + if (likely(was_frozen)) { + /* + * The list lock was not taken therefore no list + * activity can be necessary. + */ + stat(s, FREE_FROZEN); + } else if (new.frozen) { + /* + * If we just froze the page then put it onto the + * per cpu partial list. + */ put_cpu_partial(s, page, 1); stat(s, CPU_PARTIAL_FREE); } - /* - * The list lock was not taken therefore no list - * activity can be necessary. - */ - if (was_frozen) - stat(s, FREE_FROZEN); + return; } |