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Message-ID: <a0c5534a-55c6-4ca5-afe1-184fddb535c1@redhat.com>
Date: Tue, 14 May 2024 12:55:41 -0400
From: Waiman Long <longman@...hat.com>
To: Tejun Heo <tj@...nel.org>
Cc: Yury Norov <yury.norov@...il.com>, linux-kernel@...r.kernel.org,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Paul E. McKenney" <paulmck@...nel.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Anna-Maria Behnsen <anna-maria@...utronix.de>,
Ben Segall <bsegall@...gle.com>,
Daniel Bristot de Oliveira <bristot@...hat.com>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Frederic Weisbecker <frederic@...nel.org>,
Imran Khan <imran.f.khan@...cle.com>, Ingo Molnar <mingo@...hat.com>,
Johannes Weiner <hannes@...xchg.org>, Juri Lelli <juri.lelli@...hat.com>,
Leonardo Bras <leobras@...hat.com>, Mel Gorman <mgorman@...e.de>,
Peter Zijlstra <peterz@...radead.org>, Rik van Riel <riel@...riel.com>,
Steven Rostedt <rostedt@...dmis.org>, Thomas Gleixner <tglx@...utronix.de>,
Valentin Schneider <vschneid@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Zefan Li <lizefan.x@...edance.com>, cgroups@...r.kernel.org
Subject: Re: [PATCH 5/6] cgroup/cpuset: optimize
cpuset_mems_allowed_intersects()
On 5/14/24 12:50, Tejun Heo wrote:
> On Tue, May 14, 2024 at 12:47:59PM -0400, Waiman Long wrote:
>>> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
>>> index 4237c8748715..47ed206d4890 100644
>>> --- a/kernel/cgroup/cpuset.c
>>> +++ b/kernel/cgroup/cpuset.c
>>> @@ -5010,6 +5010,9 @@ EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
>>> int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
>>> const struct task_struct *tsk2)
>>> {
>>> + if (tsk1 == tsk2)
>>> + return 1;
>>> +
>>> return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
>>> }
>> Reviewed-by: Waiman Long <longman@...hat.com>
> I'm not sure this is worth the added code.
Yes, I do have a second thought afterward. The only caller of
cpuset_mems_allowed_intersects() is oom_cpuset_eligible() in
mm/oom_kill.c. So I believe a better fix is to avoid calling
cpuset_mems_allowed_intersects() there if current == tsk.
Cheers,
Longman
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