From: "Michal Koutný" <mkoutny-IBi9RG/b67k@public.gmane.org>
To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Christian Brauner
<brauner-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
John Stultz <john.stultz-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
Dmitry Shmidt <dimitrysh-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH 1/3 cgroup/for-5.20] cgroup: Elide write-locking threadgroup_rwsem when updating csses on an empty subtree
Date: Tue, 26 Jul 2022 16:31:56 +0200 [thread overview]
Message-ID: <20220726143156.GA14370@blackbody.suse.cz> (raw)
In-Reply-To: <YtDvN0wJ6CKaEPN8-NiLfg/pYEd1N0TnZuCh8vA@public.gmane.org>
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Hello.
On Thu, Jul 14, 2022 at 06:38:15PM -1000, Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> wrote:
> However, if the subtree doesn't contain any tasks, there aren't gonna
> be any cgroup migrations.
Nice catch.
> This condition can be trivially detected by testing whether
> mgctx.preloaded_src_csets is empty. Elide write-locking
> threadgroup_rwsem if the subtree is empty.
This check is perhaps even more robust than, e.g. cgroup_is_populated()
due to possible zombie cases.
> kernel/cgroup/cgroup.c | 16 +++++++++++++---
> 1 file changed, 13 insertions(+), 3 deletions(-)
Reviewed-by: Michal Koutný <mkoutny-IBi9RG/b67k@public.gmane.org>
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prev parent reply other threads:[~2022-07-26 14:31 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-15 4:38 [PATCH 1/3 cgroup/for-5.20] cgroup: Elide write-locking threadgroup_rwsem when updating csses on an empty subtree Tejun Heo
[not found] ` <YtDvN0wJ6CKaEPN8-NiLfg/pYEd1N0TnZuCh8vA@public.gmane.org>
2022-07-15 4:38 ` [PATCH 2/3 cgroup/for-5.20] cgroup: Add "no" prefixed mount options Tejun Heo
[not found] ` <YtDvU4jRPSsarcNp-NiLfg/pYEd1N0TnZuCh8vA@public.gmane.org>
2022-07-15 4:39 ` [PATCH 3/3 cgroup/for-5.20] cgroup: Make !percpu threadgroup_rwsem operations optional Tejun Heo
2022-07-23 5:12 ` Tejun Heo
2022-07-23 14:28 ` [PATCH RESEND " Tejun Heo
[not found] ` <YtwFjPnCtw8ySnuv-NiLfg/pYEd1N0TnZuCh8vA@public.gmane.org>
2022-07-25 12:12 ` Oleg Nesterov
[not found] ` <20220725121208.GB28662-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2022-07-26 23:14 ` Tejun Heo
2022-07-27 17:39 ` Oleg Nesterov
2022-07-25 14:16 ` Christian Brauner
2022-07-26 14:32 ` Michal Koutný
[not found] ` <20220726143257.GA23882-9OudH3eul5jcvrawFnH+a6VXKuFTiq87@public.gmane.org>
2022-07-26 17:33 ` Tejun Heo
2022-07-26 14:32 ` [PATCH 2/3 cgroup/for-5.20] cgroup: Add "no" prefixed mount options Michal Koutný
[not found] ` <20220726143246.GA23794-9OudH3eul5jcvrawFnH+a6VXKuFTiq87@public.gmane.org>
2022-07-26 20:01 ` Tejun Heo
2022-07-26 23:30 ` Tejun Heo
[not found] ` <YuB5ICv3bXsy5Xuh-NiLfg/pYEd1N0TnZuCh8vA@public.gmane.org>
2022-07-26 23:48 ` [PATCH cgroup/for-5.20] cgroup: remove "no" prefixed mount options options Tejun Heo
[not found] ` <YuB9QXapVUy1t8TZ-NiLfg/pYEd1N0TnZuCh8vA@public.gmane.org>
2022-07-27 9:27 ` Michal Koutný
[not found] ` <20220727092715.GA1569-9OudH3eul5jcvrawFnH+a6VXKuFTiq87@public.gmane.org>
2022-07-27 17:55 ` Tejun Heo
2022-07-26 14:31 ` Michal Koutný [this message]
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