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From: "Michal Koutný" <mkoutny@suse.com>
To: Tejun Heo <tj@kernel.org>
Cc: Waiman Long <longman@redhat.com>,
	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>
Subject: Re: [PATCH v11 7/8] cgroup/cpuset: Update description of cpuset.cpus.partition in cgroup-v2.rst
Date: Tue, 14 Jun 2022 13:53:45 +0200	[thread overview]
Message-ID: <20220614115345.GA6771@blackbody.suse.cz> (raw)
In-Reply-To: <Yqd7WMFj6AEyV3Cy@slm.duckdns.org>

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On Mon, Jun 13, 2022 at 08:00:56AM -1000, Tejun Heo <tj@kernel.org> wrote:
> Yeah, I don't know why this part is different from any other errors that the
> parent can make.

It's different because a write to parent's cpuset.cpus is independent of
whether cpuset.cpus of its children are exclusive or not.
In an extreme case the children may be non-exclusive

    parent	cpuset.cpus=0-3 //   valid partition
    `- child_1	cpuset.cpus=0-1	// invalid partition
    `- child_2	cpuset.cpus=1-2 // invalid partition

but the parent can still be a valid partition (thanks to cpu no. 3 in
the example above).

Do I miss anything?

Thanks,
Michal

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WARNING: multiple messages have this Message-ID (diff)
From: "Michal Koutný" <mkoutny-IBi9RG/b67k@public.gmane.org>
To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Waiman Long <longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	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>
Subject: Re: [PATCH v11 7/8] cgroup/cpuset: Update description of cpuset.cpus.partition in cgroup-v2.rst
Date: Tue, 14 Jun 2022 13:53:45 +0200	[thread overview]
Message-ID: <20220614115345.GA6771@blackbody.suse.cz> (raw)
In-Reply-To: <Yqd7WMFj6AEyV3Cy-NiLfg/pYEd1N0TnZuCh8vA@public.gmane.org>

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On Mon, Jun 13, 2022 at 08:00:56AM -1000, Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> wrote:
> Yeah, I don't know why this part is different from any other errors that the
> parent can make.

It's different because a write to parent's cpuset.cpus is independent of
whether cpuset.cpus of its children are exclusive or not.
In an extreme case the children may be non-exclusive

    parent	cpuset.cpus=0-3 //   valid partition
    `- child_1	cpuset.cpus=0-1	// invalid partition
    `- child_2	cpuset.cpus=1-2 // invalid partition

but the parent can still be a valid partition (thanks to cpu no. 3 in
the example above).

Do I miss anything?

Thanks,
Michal

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  reply	other threads:[~2022-06-14 11:53 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-10 15:34 [PATCH v11 0/8] cgroup/cpuset: cpu partition code enhancements Waiman Long
2022-05-10 15:34 ` [PATCH v11 1/8] cgroup/cpuset: Add top_cpuset check in update_tasks_cpumask() Waiman Long
2022-05-10 15:34   ` Waiman Long
2022-05-10 15:34 ` [PATCH v11 2/8] cgroup/cpuset: Miscellaneous cleanups & add helper functions Waiman Long
2022-05-10 15:34 ` [PATCH v11 3/8] cgroup/cpuset: Allow no-task partition to have empty cpuset.cpus.effective Waiman Long
2022-06-12 17:40   ` Tejun Heo
2022-06-12 17:41     ` Tejun Heo
2022-06-13  2:53       ` Waiman Long
2022-06-13  2:55         ` Tejun Heo
2022-06-13  3:04           ` Waiman Long
2022-06-13  3:04             ` Waiman Long
2022-06-13 14:02           ` Michal Koutný
2022-06-13 14:02             ` Michal Koutný
2022-06-13 16:47             ` Waiman Long
2022-06-13 16:47               ` Waiman Long
2022-06-13 17:23               ` Tejun Heo
2022-06-13  2:50     ` Waiman Long
2022-05-10 15:34 ` [PATCH v11 4/8] cgroup/cpuset: Relax constraints to partition & cpus changes Waiman Long
2022-05-10 15:34   ` Waiman Long
2022-05-10 15:34 ` [PATCH v11 5/8] cgroup/cpuset: Add a new isolated cpus.partition type Waiman Long
2022-05-10 15:34   ` Waiman Long
2022-05-10 15:34 ` [PATCH v11 6/8] cgroup/cpuset: Show invalid partition reason string Waiman Long
2022-05-10 15:34 ` [PATCH v11 7/8] cgroup/cpuset: Update description of cpuset.cpus.partition in cgroup-v2.rst Waiman Long
2022-06-12 17:49   ` Tejun Heo
2022-06-13  3:02     ` Waiman Long
2022-06-13  3:12       ` Tejun Heo
2022-06-13  3:12         ` Tejun Heo
2022-06-13 13:18         ` Waiman Long
2022-06-13 17:06           ` Waiman Long
2022-06-13 14:24         ` Michal Koutný
2022-06-13 14:24           ` Michal Koutný
2022-06-13 17:28           ` Tejun Heo
2022-06-13 17:55             ` Michal Koutný
2022-06-13 18:00               ` Tejun Heo
2022-06-13 18:00                 ` Tejun Heo
2022-06-14 11:53                 ` Michal Koutný [this message]
2022-06-14 11:53                   ` Michal Koutný
2022-06-27 19:10                   ` Tejun Heo
2022-06-27 19:10                     ` Tejun Heo
2022-06-30 14:32                     ` Michal Koutný
2022-06-30 22:53                       ` Tejun Heo
2022-05-10 15:34 ` [PATCH v11 8/8] kselftest/cgroup: Add cpuset v2 partition root state test Waiman Long
2022-05-21 10:24   ` Muhammad Usama Anjum
2022-05-21 10:24     ` Muhammad Usama Anjum
2022-05-22  2:40     ` Waiman Long
2022-05-20 16:00 ` [PATCH v11 0/8] cgroup/cpuset: cpu partition code enhancements Sebastian Andrzej Siewior
2022-05-20 16:46   ` Waiman Long
2022-05-24 16:48     ` Sebastian Andrzej Siewior

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