From: <wuyun.wu@huawei.com>
To: Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
"David Rientjes" <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
"Andrew Morton" <akpm@linux-foundation.org>
Cc: <hewenliang4@huawei.com>, <hushiyuan@huawei.com>,
Abel Wu <wuyun.wu@huawei.com>,
"open list:SLAB ALLOCATOR" <linux-mm@kvack.org>,
"open list" <linux-kernel@vger.kernel.org>
Subject: [PATCH] mm/slub: branch optimization in free slowpath
Date: Thu, 13 Aug 2020 18:18:08 +0800 [thread overview]
Message-ID: <20200813101812.1617-1-wuyun.wu@huawei.com> (raw)
From: Abel Wu <wuyun.wu@huawei.com>
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>
---
mm/slub.c | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c
index 4f496ae5a820..f9182a760675 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2958,20 +2958,21 @@ 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;
}
--
2.28.0.windows.1
next reply other threads:[~2020-08-13 10:18 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-13 10:18 wuyun.wu [this message]
2020-08-13 16:47 ` [PATCH] mm/slub: branch optimization in free slowpath Christopher Lameter
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200813101812.1617-1-wuyun.wu@huawei.com \
--to=wuyun.wu@huawei.com \
--cc=akpm@linux-foundation.org \
--cc=cl@linux.com \
--cc=hewenliang4@huawei.com \
--cc=hushiyuan@huawei.com \
--cc=iamjoonsoo.kim@lge.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=penberg@kernel.org \
--cc=rientjes@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).