From: Tejun Heo <tj@kernel.org>
To: Roman Gushchin <guroan@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>,
cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-team@fb.com, Roman Gushchin <guro@fb.com>
Subject: Re: [PATCH v3 3/7] cgroup: protect cgroup->nr_(dying_)descendants by css_set_lock
Date: Tue, 20 Nov 2018 08:18:18 -0800 [thread overview]
Message-ID: <20181120161818.GT2509588@devbig004.ftw2.facebook.com> (raw)
In-Reply-To: <20181117003830.15344-4-guro@fb.com>
On Fri, Nov 16, 2018 at 04:38:26PM -0800, Roman Gushchin wrote:
> Now the number of descendant cgroups and the number of dying
> descendant cgroups are synchronized using the cgroup_mutex.
>
> The number of descendant cgroups will be required by the cgroup v2
> freezer, which will use it to determine if a cgroup is frozen
> (depending on total number of descendants and number of frozen
> descendants). It's not always acceptable to grab the cgroup_mutex,
> especially from quite hot paths (e.g. exit()).
>
> To avoid this, let's additionally synchronize these counters
> using the css_set_lock.
Can you change it so that writes are cgroup_mutex and css_set_lock
protected and reads can be done under either cgroup_mutex or
css_set_lock?
Thanks.
--
tejun
next prev parent reply other threads:[~2018-11-20 16:18 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-17 0:38 [PATCH v3 0/7] freezer for cgroup v2 Roman Gushchin
2018-11-17 0:38 ` [PATCH v3 1/7] cgroup: rename freezer.c into legacy_freezer.c Roman Gushchin
2018-11-17 0:38 ` [PATCH v3 2/7] cgroup: implement __cgroup_task_count() helper Roman Gushchin
2018-11-17 0:38 ` [PATCH v3 3/7] cgroup: protect cgroup->nr_(dying_)descendants by css_set_lock Roman Gushchin
2018-11-20 16:18 ` Tejun Heo [this message]
2018-11-17 0:38 ` [PATCH v3 4/7] cgroup: cgroup v2 freezer Roman Gushchin
2018-11-20 16:25 ` Tejun Heo
2018-11-20 16:33 ` Roman Gushchin
2018-11-20 16:36 ` Tejun Heo
2018-11-20 16:43 ` Roman Gushchin
2018-11-20 16:48 ` Tejun Heo
2018-11-20 17:39 ` Roman Gushchin
2018-11-20 18:05 ` Tejun Heo
2018-11-17 0:38 ` [PATCH v3 5/7] kselftests: cgroup: don't fail on cg_kill_all() error in cg_destroy() Roman Gushchin
2018-11-17 0:38 ` [PATCH v3 6/7] kselftests: cgroup: add freezer controller self-tests Roman Gushchin
2018-11-17 0:38 ` [PATCH v3 7/7] cgroup: document cgroup v2 freezer interface Roman Gushchin
2018-11-17 8:02 ` Mike Rapoport
2018-11-19 17:42 ` Roman Gushchin
2018-11-20 14:06 ` Mike Rapoport
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=20181120161818.GT2509588@devbig004.ftw2.facebook.com \
--to=tj@kernel.org \
--cc=cgroups@vger.kernel.org \
--cc=guro@fb.com \
--cc=guroan@gmail.com \
--cc=kernel-team@fb.com \
--cc=linux-kernel@vger.kernel.org \
--cc=oleg@redhat.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).