From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: "Michal Koutný" <mkoutny-IBi9RG/b67k@public.gmane.org>
Cc: Waiman Long <longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
Juri Lelli <juri.lelli-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Vincent Guittot
<vincent.guittot-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
Dietmar Eggemann <dietmar.eggemann-5wv7dgnIgG8@public.gmane.org>,
Steven Rostedt <rostedt-nx8X9YLhiw1AfugRpC6u6w@public.gmane.org>,
Ben Segall <bsegall-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
Mel Gorman <mgorman-l3A5Bk7waGM@public.gmane.org>,
Daniel Bristot de Oliveira
<bristot-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Valentin Schneider
<vschneid-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Zefan Li <lizefan.x-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org>,
Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>,
cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH 2/2] cgroup: Skip subtree root in cgroup_update_dfl_csses()
Date: Thu, 28 Jul 2022 07:26:05 -1000 [thread overview]
Message-ID: <YuLGrXyXj6a2yigJ@slm.duckdns.org> (raw)
In-Reply-To: <20220728144426.GA26631-9OudH3eul5jcvrawFnH+a6VXKuFTiq87@public.gmane.org>
On Thu, Jul 28, 2022 at 04:44:26PM +0200, Michal Koutný wrote:
> On Wed, Jul 27, 2022 at 08:58:15PM -0400, Waiman Long <longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> > The cgroup_update_dfl_csses() function updates css associations when a
> > cgroup's subtree_control file is modified. Any changes made to a cgroup's
> > subtree_control file, however, will only affect its descendants but not
> > the cgroup itself.
>
> I find this correct.
>
> > So there is no point in migrating csses associated with that cgroup.
> > We can skip them instead.
>
> Alone it's not such a big win but it componds with the recent Tejun's
> threadgroup_rwsem elision.
The chance is that if you're writing to a cgroup's subtree_control, that
cgroup is gonna be empty. The only case I can think of that this would make
a difference is w/ threaded cgroups, but it does make sense.
Thanks.
--
tejun
next prev parent reply other threads:[~2022-07-28 17:26 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-28 0:58 [PATCH 1/2] cgroup/cpuset: Keep current cpus list if cpus affinity was explicitly set Waiman Long
[not found] ` <20220728005815.1715522-1-longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2022-07-28 0:58 ` [PATCH 2/2] cgroup: Skip subtree root in cgroup_update_dfl_csses() Waiman Long
[not found] ` <20220728005815.1715522-2-longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2022-07-28 14:44 ` Michal Koutný
2022-07-28 14:49 ` Waiman Long
[not found] ` <20220728144426.GA26631-9OudH3eul5jcvrawFnH+a6VXKuFTiq87@public.gmane.org>
2022-07-28 17:26 ` Tejun Heo [this message]
2022-07-28 17:27 ` Tejun Heo
2022-07-28 14:44 ` [PATCH 1/2] cgroup/cpuset: Keep current cpus list if cpus affinity was explicitly set Michal Koutný
[not found] ` <20220728144420.GA27407-9OudH3eul5jcvrawFnH+a6VXKuFTiq87@public.gmane.org>
2022-07-28 14:59 ` Waiman Long
[not found] ` <a58852b4-313a-9271-f31d-f79a91ec188b-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2022-07-28 15:23 ` Michal Koutný
[not found] ` <20220728152355.GB25894-9OudH3eul5jcvrawFnH+a6VXKuFTiq87@public.gmane.org>
2022-07-28 15:35 ` Waiman Long
2022-07-28 16:50 ` Valentin Schneider
[not found] ` <xhsmhbkt9dvwm.mognet-lVOlpLwaOlUmbyhZVYo91WPO1xz+ivuR@public.gmane.org>
2022-07-28 17:42 ` Waiman Long
2022-07-28 17:23 ` Tejun Heo
2022-07-28 18:57 ` Waiman Long
[not found] ` <1ae1cc6c-dca9-4958-6b22-24a5777c5e8d-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2022-07-28 19:02 ` Tejun Heo
[not found] ` <YuLdX7BYGvo57LNU-NiLfg/pYEd1N0TnZuCh8vA@public.gmane.org>
2022-07-28 19:21 ` Waiman Long
2022-07-28 20:44 ` Tejun Heo
2022-07-28 21:04 ` Waiman Long
[not found] ` <c470d3f7-f0f8-b8e6-4a95-7b334f0a824b-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2022-07-28 21:39 ` Tejun Heo
[not found] ` <YuMCB86fH2K3NcqM-NiLfg/pYEd1N0TnZuCh8vA@public.gmane.org>
2022-07-29 14:15 ` Valentin Schneider
[not found] ` <xhsmhy1wcc8dq.mognet-lVOlpLwaOlUmbyhZVYo91WPO1xz+ivuR@public.gmane.org>
2022-07-29 14:50 ` Waiman Long
[not found] ` <92f68392-12d2-f64a-9bb9-1a3a15f99d02-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2022-07-29 18:31 ` Waiman Long
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