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From: Waiman Long <longman@redhat.com>
To: Joel Fernandes <joel@joelfernandes.org>, Tejun Heo <tj@kernel.org>
Cc: Sonny Rao <sonnyrao@google.com>,
	linux-kernel@vger.kernel.org,
	Dmitry Shmidt <dimitrysh@google.com>,
	Amit Pundir <amit.pundir@linaro.org>,
	kernel-team@android.com, Jesse Barnes <jsbarnes@google.com>,
	vpillai@digitalocean.com, Peter Zijlstra <peterz@infradead.org>,
	Guenter Roeck <groeck@chromium.org>,
	Greg Kerr <kerrnel@google.com>,
	cgroups@vger.kernel.org, Johannes Weiner <hannes@cmpxchg.org>,
	Li Zefan <lizefan@huawei.com>
Subject: Re: [PATCH RFC] cpuset: Make cpusets get restored on hotplug
Date: Thu, 26 Mar 2020 21:26:51 -0400	[thread overview]
Message-ID: <592d4120-0b42-4607-5efd-fb2d4d29f0cc@redhat.com> (raw)
In-Reply-To: <20200326202340.GA146657@google.com>

On 3/26/20 4:23 PM, Joel Fernandes wrote:
> On Thu, Mar 26, 2020 at 04:18:59PM -0400, Tejun Heo wrote: >> On Thu, Mar 26, 2020 at 01:05:04PM -0700, Sonny Rao wrote: >>> I am
surprised if anyone actually wants this behavior, we (Chrome >>> OS) >>
>> The behavior is silly but consistent in that it doesn't allow empty
>> active cpusets and it has been like that for many many years now. >>
>>> found out about it accidentally, and then found that Android had >>>
been carrying a patch to fix it. And if it were a desirable >>> behavior
then why isn't it an option in v2? >> >> Nobody is saying it's a good
behavior (hence the change in cgroup2) >> and there are situations where
changing things like this is >> justifiable, but, here: >> >> * The
proposed change makes the interface inconsistent and does so >>
unconditionally on what is now a mostly legacy interface. >> >> * There
already is a newer version of the interface which includes >> the
desired behavior. >> >> * I forgot but as Waiman pointed out, you can
even opt-in to the >> new behavior, which is more comprehensive without
the >> inconsitencies, while staying on cgroup1. > > Thank you Tejun,
Waiman and Sonny. I confirmed the cgroup_v2_mode > option fixes cgroup
v1's broken behavior. > > We will use this mount option on our systems
to fix it.
I am glad that it works for you.

I think the problem is that the v2_mode mount option is not that well
documented. Maybe I should send a patch to add some some description
about it in cgroup-v2.rst or cgroup-v1/cpusets.rst.

Cheers,
Longman




  reply	other threads:[~2020-03-27  1:30 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-26 19:16 [PATCH RFC] cpuset: Make cpusets get restored on hotplug Joel Fernandes (Google)
2020-03-26 19:20 ` Tejun Heo
2020-03-26 19:44   ` Joel Fernandes
2020-03-26 19:48     ` Tejun Heo
2020-03-26 19:57     ` Waiman Long
2020-03-26 20:05       ` Sonny Rao
2020-03-26 20:18         ` Tejun Heo
2020-03-26 20:23           ` Joel Fernandes
2020-03-27  1:26             ` Waiman Long [this message]
2020-03-27  3:32               ` Joel Fernandes
2020-03-26 21:47         ` Waiman Long
2020-03-26 22:03           ` Sonny Rao
2021-10-26 23:58       ` Barry Song
2021-10-27  1:06         ` Waiman Long
2021-10-27  2:21           ` Barry Song
2021-10-27  2:35             ` Waiman Long
2021-10-27  2:42               ` Barry Song

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