Received-SPF: pass (google.com: domain of linux-kernel+bounces-178973-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) client-ip=147.75.48.161;
Message-ID: <a0c5534a-55c6-4ca5-afe1-184fddb535c1@redhat.com>
Date: Tue, 14 May 2024 12:55:41 -0400
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH 5/6] cgroup/cpuset: optimize
 cpuset_mems_allowed_intersects()
To: Tejun Heo <tj@kernel.org>
Cc: Yury Norov <yury.norov@gmail.com>, linux-kernel@vger.kernel.org,
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
 "Paul E. McKenney" <paulmck@kernel.org>,
 "Rafael J. Wysocki" <rafael@kernel.org>,
 Anna-Maria Behnsen <anna-maria@linutronix.de>,
 Ben Segall <bsegall@google.com>,
 Daniel Bristot de Oliveira <bristot@redhat.com>,
 Dietmar Eggemann <dietmar.eggemann@arm.com>,
 Frederic Weisbecker <frederic@kernel.org>,
 Imran Khan <imran.f.khan@oracle.com>, Ingo Molnar <mingo@redhat.com>,
 Johannes Weiner <hannes@cmpxchg.org>, Juri Lelli <juri.lelli@redhat.com>,
 Leonardo Bras <leobras@redhat.com>, Mel Gorman <mgorman@suse.de>,
 Peter Zijlstra <peterz@infradead.org>, Rik van Riel <riel@surriel.com>,
 Steven Rostedt <rostedt@goodmis.org>, Thomas Gleixner <tglx@linutronix.de>,
 Valentin Schneider <vschneid@redhat.com>,
 Vincent Guittot <vincent.guittot@linaro.org>,
 Zefan Li <lizefan.x@bytedance.com>, cgroups@vger.kernel.org
References: <20240513220146.1461457-1-yury.norov@gmail.com>
 <20240513220146.1461457-6-yury.norov@gmail.com>
 <911ca229-4849-4fd2-8ae8-5ca653d8a5e3@redhat.com>
 <ZkOWRa_hFFhcbpVf@slm.duckdns.org>
Content-Language: en-US
From: Waiman Long <longman@redhat.com>
In-Reply-To: <ZkOWRa_hFFhcbpVf@slm.duckdns.org>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit


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@redhat.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