From: Tejun Heo <tj@kernel.org> To: Waiman Long <longman@redhat.com> Cc: "Zefan Li" <lizefan.x@bytedance.com>, "Johannes Weiner" <hannes@cmpxchg.org>, "Jonathan Corbet" <corbet@lwn.net>, "Shuah Khan" <shuah@kernel.org>, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, "Andrew Morton" <akpm@linux-foundation.org>, "Roman Gushchin" <guro@fb.com>, "Phil Auld" <pauld@redhat.com>, "Peter Zijlstra" <peterz@infradead.org>, "Juri Lelli" <juri.lelli@redhat.com>, "Frederic Weisbecker" <frederic@kernel.org>, "Marcelo Tosatti" <mtosatti@redhat.com>, "Michal Koutný" <mkoutny@suse.com> Subject: Re: [PATCH v4 4/6] cgroup/cpuset: Allow non-top parent partition root to distribute out all CPUs Date: Wed, 11 Aug 2021 08:13:33 -1000 [thread overview] Message-ID: <YRQTTf+bJZ8f3O3+@slm.duckdns.org> (raw) In-Reply-To: <20210811030607.13824-5-longman@redhat.com> On Tue, Aug 10, 2021 at 11:06:05PM -0400, Waiman Long wrote: > Currently, a parent partition root cannot distribute all its CPUs to > child partition roots with no CPUs left. However in some use cases, > a management application may want to create a parent partition root as > a management unit with no task associated with it and has all its CPUs > distributed to various child partition roots dynamically according to > their needs. Leaving a cpu in the parent partition root in such a case is > now a waste. > > To accommodate such use cases, a parent partition root can now have > all its CPUs distributed to its child partition roots as long as: > 1) it is not the top cpuset; and > 2) there is no task directly associated with the parent. > > Once an empty parent partition root is formed, no new task can be moved > into it. The above are already enforced by cgroup2 core, right? No intermediate cgroup with controllers enabled can have processes. From controllers' POV, only leaves can have processes. Thanks. -- tejun
WARNING: multiple messages have this Message-ID (diff)
From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> To: Waiman Long <longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Cc: "Zefan Li" <lizefan.x-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org>, "Johannes Weiner" <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, "Jonathan Corbet" <corbet-T1hC0tSOHrs@public.gmane.org>, "Shuah Khan" <shuah-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kselftest-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, "Andrew Morton" <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, "Roman Gushchin" <guro-b10kYP2dOMg@public.gmane.org>, "Phil Auld" <pauld-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, "Peter Zijlstra" <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, "Juri Lelli" <juri.lelli-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, "Frederic Weisbecker" <frederic-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, "Marcelo Tosatti" <mtosatti-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, "Michal Koutný" <mkoutny-IBi9RG/b67k@public.gmane.org> Subject: Re: [PATCH v4 4/6] cgroup/cpuset: Allow non-top parent partition root to distribute out all CPUs Date: Wed, 11 Aug 2021 08:13:33 -1000 [thread overview] Message-ID: <YRQTTf+bJZ8f3O3+@slm.duckdns.org> (raw) In-Reply-To: <20210811030607.13824-5-longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> On Tue, Aug 10, 2021 at 11:06:05PM -0400, Waiman Long wrote: > Currently, a parent partition root cannot distribute all its CPUs to > child partition roots with no CPUs left. However in some use cases, > a management application may want to create a parent partition root as > a management unit with no task associated with it and has all its CPUs > distributed to various child partition roots dynamically according to > their needs. Leaving a cpu in the parent partition root in such a case is > now a waste. > > To accommodate such use cases, a parent partition root can now have > all its CPUs distributed to its child partition roots as long as: > 1) it is not the top cpuset; and > 2) there is no task directly associated with the parent. > > Once an empty parent partition root is formed, no new task can be moved > into it. The above are already enforced by cgroup2 core, right? No intermediate cgroup with controllers enabled can have processes. From controllers' POV, only leaves can have processes. Thanks. -- tejun
next prev parent reply other threads:[~2021-08-11 18:13 UTC|newest] Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-08-11 3:06 [PATCH-cgroup v4 0/6] cgroup/cpuset: Add new cpuset partition type & empty effecitve cpus Waiman Long 2021-08-11 3:06 ` [PATCH v4 1/6] cgroup/cpuset: Enable event notification when partition state changes Waiman Long 2021-08-11 3:06 ` Waiman Long 2021-08-11 18:04 ` Tejun Heo 2021-08-11 18:04 ` Tejun Heo 2021-08-11 3:06 ` [PATCH v4 2/6] cgroup/cpuset: Properly handle partition root tree Waiman Long 2021-08-11 18:08 ` Tejun Heo 2021-08-11 19:27 ` Waiman Long 2021-08-11 19:27 ` Waiman Long 2021-08-12 22:18 ` Tejun Heo 2021-08-12 22:18 ` Tejun Heo 2021-08-12 22:56 ` Waiman Long 2021-08-12 22:56 ` Waiman Long 2021-08-13 16:07 ` Tejun Heo 2021-08-11 3:06 ` [PATCH v4 3/6] cgroup/cpuset: Add a new isolated cpus.partition type Waiman Long 2021-08-11 3:06 ` [PATCH v4 4/6] cgroup/cpuset: Allow non-top parent partition root to distribute out all CPUs Waiman Long 2021-08-11 18:13 ` Tejun Heo [this message] 2021-08-11 18:13 ` Tejun Heo 2021-08-11 18:18 ` Waiman Long 2021-08-11 18:21 ` Tejun Heo 2021-08-11 18:21 ` Tejun Heo 2021-08-11 18:46 ` Waiman Long 2021-08-11 18:46 ` Waiman Long 2021-08-12 21:51 ` Tejun Heo 2021-08-12 21:51 ` Tejun Heo 2021-08-11 3:06 ` [PATCH v4 5/6] cgroup/cpuset: Update description of cpuset.cpus.partition in cgroup-v2.rst Waiman Long 2021-08-11 18:15 ` Tejun Heo 2021-08-11 18:19 ` Waiman Long 2021-08-11 18:19 ` Waiman Long 2021-08-11 3:06 ` [PATCH v4 6/6] kselftest/cgroup: Add cpuset v2 partition root state test Waiman Long
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