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Date:   Thu, 10 Nov 2022 15:42:43 +0100
From:   Michal =?iso-8859-1?Q?Koutn=FD?= <mkoutny@suse.com>
To:     Lu Jialin <lujialin4@huawei.com>
Cc:     Johannes Weiner <hannes@cmpxchg.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Michal Hocko <mhocko@kernel.org>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Shakeel Butt <shakeelb@google.com>,
        Muchun Song <songmuchun@bytedance.com>,
        cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org
Subject: Re: [PATCH] mm/memcontrol.c: drains percpu charge caches in
 memory.reclaim
Message-ID: <20221110144243.GA10562@blackbody.suse.cz>
References: <20221110065316.67204-1-lujialin4@huawei.com>
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Hello Jialin.

On Thu, Nov 10, 2022 at 02:53:16PM +0800, Lu Jialin <lujialin4@huawei.com> wrote:
> When user use memory.reclaim to reclaim memory, after drain percpu lru
> caches, drain percpu charge caches for given memcg stock in the hope
> of introducing more evictable pages.

Do you have any data on materialization of this hope?

IIUC, the stock is useful for batched accounting to page_counter but it
doesn't represent real pages. I.e. your change may reduce the
page_counter value but it would not release any pages. Or have I missed
a way how it helps with the reclaim?

Thanks,
Michal

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