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From:   "T.J. Mercier" <tjmercier@google.com>
Date:   Thu, 19 Oct 2023 09:01:43 -0700
Message-ID: <CABdmKX21QfTDXJ2o=CbATmeX1OSgB1XnM=escE7xf8gMrvMhGA@mail.gmail.com>
Subject: Re: [PATCH 0/3 RESEND] Per memcg lru_gen node stat
To:     Huan Yang <link@vivo.com>
Cc:     Yu Zhao <yuzhao@google.com>, Jonathan Corbet <corbet@lwn.net>,
        Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Michal Hocko <mhocko@kernel.org>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Shakeel Butt <shakeelb@google.com>,
        Muchun Song <muchun.song@linux.dev>,
        Peter Xu <peterx@redhat.com>,
        David Hildenbrand <david@redhat.com>,
        "T.J. Alumbaugh" <talumbau@google.com>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Ryan Roberts <ryan.roberts@arm.com>,
        Kefeng Wang <wangkefeng.wang@huawei.com>,
        Suren Baghdasaryan <surenb@google.com>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:MEMORY MANAGEMENT" <linux-mm@kvack.org>,
        "open list:CONTROL GROUP - MEMORY RESOURCE CONTROLLER (MEMCG)" 
        <cgroups@vger.kernel.org>, opensource.kernel@vivo.com
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On Wed, Oct 18, 2023 at 7:32=E2=80=AFPM Huan Yang <link@vivo.com> wrote:
> > Android can't use debugfs in production, but I
> > think we'd prefer to use memory.reclaim for eviction anyway because it
> > respects memcg limits and reclaims from slab.
> Yes, shrink control this actually can use proactive reclaim.
> >
> > So maybe it's possible to add just aging functionality specific to
> > MGLRU? It'd be nice to know how you're going to use the aging, or why
> Due to debugfs not always mount, if we want to now lrugen's info, maybe
> nice to offer a memcg's node to show per memcg's lrugen info.
> > you want this version of eviction instead of what memory.reclaim does.
>
I think Yu's inquiry was about whether you will look at the lrugen
info from the memcg file for a production use case, or just for
debugging where you don't have debugfs for some reason. Because it's a
long term commitment to add the file.