From: Waiman Long <llong@redhat.com>
To: Tejun Heo <tj@kernel.org>, Waiman Long <llong@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 14:46:24 -0400 [thread overview]
Message-ID: <ef02d96b-325c-87f6-a6a3-d840feefef24@redhat.com> (raw)
In-Reply-To: <YRQVFkNX5DcKixzy@slm.duckdns.org>
On 8/11/21 2:21 PM, Tejun Heo wrote:
> On Wed, Aug 11, 2021 at 02:18:17PM -0400, Waiman Long wrote:
>> I don't think that is true. A task can reside anywhere in the cgroup
>> hierarchy. I have encountered no problem moving tasks around.
> Oh, that shouldn't be happening with controllers enabled. Can you please
> share a repro?
I have done further testing. Enabling controllers won't prohibit moving
a task into a parent cgroup as long as the child cgroups have no tasks.
Once the child cgroup has task, moving another task to the parent is not
allowed (-EBUSY). Similarly if a parent cgroup has tasks, you can't put
new tasks into the child cgroup. I don't realize that we have such
constraints as I usually do my testing with a cgroup hierarchy with no
tasks initially. Anyway, a new lesson learned.
I will try to see how to address that in the patch, but the additional
check added is still valid in some special case.
Cheers,
Longman
next prev parent reply other threads:[~2021-08-11 18:46 UTC|newest]
Thread overview: 20+ 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 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
2021-08-12 22:18 ` Tejun Heo
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
2021-08-11 18:18 ` Waiman Long
2021-08-11 18:21 ` Tejun Heo
2021-08-11 18:46 ` Waiman Long [this message]
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 3:06 ` [PATCH v4 6/6] kselftest/cgroup: Add cpuset v2 partition root state test Waiman Long
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