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From:   Yosry Ahmed <yosryahmed@google.com>
Date:   Wed, 25 May 2022 13:31:42 -0700
Message-ID: <CAJD7tkb7DRK_9wtiSFPiV6zsZGYYxs_JGECODtP+pta4k4MaiA@mail.gmail.com>
Subject: Re: [PATCH] memcg: provide reclaim stats via 'memory.reclaim'
To:     Michal Hocko <mhocko@suse.com>
Cc:     Johannes Weiner <hannes@cmpxchg.org>,
        Vaibhav Jain <vaibhav@linux.ibm.com>,
        Cgroups <cgroups@vger.kernel.org>, linux-doc@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux-MM <linux-mm@kvack.org>, Tejun Heo <tj@kernel.org>,
        Zefan Li <lizefan.x@bytedance.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Vladimir Davydov <vdavydov.dev@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
        Shakeel Butt <shakeelb@google.com>,
        David Rientjes <rientjes@google.com>
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On Wed, May 25, 2022 at 1:59 AM Michal Hocko <mhocko@suse.com> wrote:
>
> On Tue 24-05-22 12:01:01, Yosry Ahmed wrote:
> > On Tue, May 24, 2022 at 4:45 AM Johannes Weiner <hannes@cmpxchg.org> wrote:
> > >
> > > On Mon, May 23, 2022 at 03:50:34PM -0700, Yosry Ahmed wrote:
> > > > I think it might be useful to have a dedicated entry in memory.stat
> > > > for proactively reclaimed memory. A case where this would be useful is
> > > > tuning and evaluating userspace proactive reclaimers. For instance, if
> > > > a userspace agent is asking the kernel to reclaim 100M, but it could
> > > > only reclaim 10M, then most probably the proactive reclaimer is not
> > > > using a good methodology to figure out how much memory do we need to
> > > > reclaim.
> > > >
> > > > IMO this is more useful, and a superset of just reading the last
> > > > reclaim request status through memory.reclaim (read stat before and
> > > > after).
> > >
> > > +1
> >
> > It might also be useful to have a breakdown of this by memory type:
> > file, anon, or shrinkers.
> >
> > It would also fit in nicely with a potential type=file/anon/shrinker
> > argument to memory.reclaim. Thoughts on this?
>
> Can we start simple and see what real usecases actually will need?

Agreed. Let's start with a single proactively reclaimed memory stat
and then add subcategories if/when needed.

> --
> Michal Hocko
> SUSE Labs