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

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Message-ID: <4c7db101-a34f-47ff-ba64-952516cc193a@vivo.com>
Date:   Wed, 8 Nov 2023 16:26:14 +0800
From:   Huan Yang <link@...o.com>
To:     Yosry Ahmed <yosryahmed@...gle.com>, Wei Xu <weixugc@...gle.com>,
        David Rientjes <rientjes@...gle.com>
Cc:     Tejun Heo <tj@...nel.org>, Zefan Li <lizefan.x@...edance.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Jonathan Corbet <corbet@....net>,
        Michal Hocko <mhocko@...nel.org>,
        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>,
        Huang Ying <ying.huang@...el.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Peter Xu <peterx@...hat.com>,
        "Vishal Moola (Oracle)" <vishal.moola@...il.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


在 2023/11/8 16:00, Yosry Ahmed 写道:
> +Wei Xu +David Rientjes
>
> On Tue, Nov 7, 2023 at 10:59 PM Huan Yang <link@...o.com> wrote:
>> In some cases, we need to selectively reclaim file pages or anonymous
>> pages in an unbalanced manner.
>>
>> For example, when an application is pushed to the background and frozen,
>> it may not be opened for a long time, and we can safely reclaim the
>> application's anonymous pages, but we do not want to touch the file pages.
>>
>> This patchset extends the proactive reclaim interface to achieve
>> unbalanced reclamation. Users can control the reclamation tendency by
>> inputting swappiness under the original interface. Specifically, users
>> can input special values to extremely reclaim specific pages.
> I proposed this a while back:
>
> https://lore.kernel.org/linux-mm/CAJD7tkbDpyoODveCsnaqBBMZEkDvshXJmNdbk51yKSNgD7aGdg@mail.gmail.com/
Well to know this, proactive reclaim single type is usefull in our 
production too.
>
> The takeaway from the discussion was that swappiness is not the right
> way to do this. We can add separate arguments to specify types of
> memory to reclaim, as Roman suggested in that thread. I had some
> patches lying around to do that at some point, I can dig them up if
> that's helpful, but they are probably based on a very old kernel now,
> and before MGLRU landed. IIRC it wasn't very difficult, I think I
> added anon/file/shrinkers bits to struct scan_control and then plumbed
> them through to memory.reclaim.
>
>> Example:
>>          echo "1G" 200 > memory.reclaim (only reclaim anon)
>>            echo "1G" 0  > memory.reclaim (only reclaim file)
>>            echo "1G" 1  > memory.reclaim (only reclaim file)
> The type of interface here is nested-keyed, so if we add arguments
> they need to be in key=value format. Example:
>
> echo 1G swappiness=200 > memory.reclaim
Yes, this is better.
>
> As I mentioned above though, I don't think swappiness is the right way
> of doing this. Also, without swappiness, I don't think there's a v1 vs
> v2 dilemma here. memory.reclaim can work as-is in cgroup v1, it just
> needs to be exposed there.
Cgroupv1 can't use memory.reclaim, so, how to exposed it? Reclaim this by
pass memcg's ID?