linux-kernel - Re: [RFC 0/4] Introduce unbalance proactive reclaim

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Date:   Tue, 14 Nov 2023 10:54:04 +0100
From:   Michal Hocko <mhocko@...e.com>
To:     Huan Yang <link@...o.com>
Cc:     "Huang, Ying" <ying.huang@...el.com>, Tejun Heo <tj@...nel.org>,
        Zefan Li <lizefan.x@...edance.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Jonathan Corbet <corbet@....net>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Shakeel Butt <shakeelb@...gle.com>,
        Muchun Song <muchun.song@...ux.dev>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Hildenbrand <david@...hat.com>,
        Matthew Wilcox <willy@...radead.org>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Peter Xu <peterx@...hat.com>,
        "Vishal Moola (Oracle)" <vishal.moola@...il.com>,
        Yosry Ahmed <yosryahmed@...gle.com>,
        Liu Shixin <liushixin2@...wei.com>,
        Hugh Dickins <hughd@...gle.com>, cgroups@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, opensource.kernel@...o.com
Subject: Re: [RFC 0/4] Introduce unbalance proactive reclaim

On Mon 13-11-23 16:26:00, Huan Yang wrote:
[...]
> However, considering that we need to perform proactive reclaim in batches,
> suppose that only 5% of the use-once page cache in this memcg can be
> reclaimed,
> but we need to call proactive memory reclaim step by step, such as 5%, 10%,
> 15% ... 100%.

You haven't really explained this and I have asked several times IIRC.
Why do you even need to do those batches? Why cannot you simply relly on
the memory pressure triggering the memory reclaim? Do you have any
actual numbers showing that being pro-active results in smaller
latencies or anything that would show this is actually needed?

-- 
Michal Hocko
SUSE Labs