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Sender: Tejun Heo <htejun@gmail.com>
Date:   Fri, 4 Jun 2021 22:33:11 -0400
From:   Tejun Heo <tj@kernel.org>
To:     Hillf Danton <hdanton@sina.com>
Cc:     Shakeel Butt <shakeelb@google.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Muchun Song <songmuchun@bytedance.com>,
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        Andrew Morton <akpm@linux-foundation.org>,
        cgroups@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] memcg: periodically flush the memcg stats
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On Sat, Jun 05, 2021 at 09:54:21AM +0800, Hillf Danton wrote:
> The cond_resched() in cgroup_rstat_flush_locked() matches its appearence in
> your post [1]. So does unbound IMHO.

Ah yeah, this either needs CPU_INTENSIVE or UNBOUND, prolly the latter is
better.

> And the short stuff [2] looks to me like it is incorrect to queue a work
> acquiring mutex lock on to the system_wq. IOW the unbound wq is the right
> thing for any work that might sleep.

This part doesn't make sense. Blocking from per-cpu workqueue is completely
fine. What's not fine is consuming a lot of CPU cycles.

Thanks.

-- 
tejun