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Sender: Tejun Heo <htejun@gmail.com>
Date:   Wed, 25 Aug 2021 06:53:18 -1000
From:   Tejun Heo <tj@kernel.org>
To:     Nicolas Saenz Julienne <nsaenzju@redhat.com>
Cc:     cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
        lizefan.x@bytedance.com, hannes@cmpxchg.org, mtosatti@redhat.com,
        nilal@redhat.com, frederic@kernel.org, longman@redhat.com
Subject: Re: [PATCH] cgroup/cpuset: Avoid memory migration when nodemasks
 match
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References: <20210825105415.1365360-1-nsaenzju@redhat.com>
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On Wed, Aug 25, 2021 at 12:54:15PM +0200, Nicolas Saenz Julienne wrote:
> With the introduction of ee9707e8593d ("cgroup/cpuset: Enable memory
> migration for cpuset v2") attaching a process to a different cgroup will
> trigger a memory migration regardless of whether it's really needed.
> Memory migration is an expensive operation, so bypass it if the
> nodemasks passed to cpuset_migrate_mm() are equal.
> 
> Note that we're not only avoiding the migration work itself, but also a
> call to lru_cache_disable(), which triggers and flushes an LRU drain
> work on every online CPU.
> 
> Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>

Applied to cgroup/for-5.15.

Thanks.

-- 
tejun