linux-kernel - Re: [PATCH v3] vm_swappiness=0 should still try to avoid swapping anon memory

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Message-ID: <CALvZod5L+cyON5qRX3eSdHbo+-H7VDQeFuYYNqpK5diCcv9OMw@mail.gmail.com>
Date:   Tue, 10 Aug 2021 14:17:50 -0700
From:   Shakeel Butt <shakeelb@...gle.com>
To:     Nico Pache <npache@...hat.com>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Linux MM <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Rafael Aquini <aquini@...hat.com>,
        Waiman Long <llong@...hat.com>, Michal Hocko <mhocko@...e.com>,
        hakavlad@...ox.lv
Subject: Re: [PATCH v3] vm_swappiness=0 should still try to avoid swapping
 anon memory

On Tue, Aug 10, 2021 at 12:24 PM Nico Pache <npache@...hat.com> wrote:
>
>
[...]
> >
> > I'm wondering how you're getting anon scans with swappiness=0. If you
> > look at get_scan_count(), SCAN_FRACT with swappines=0 should always
> > result in ap = fraction[0] = 0, which never yields any anon scan
> > targets. So I'm thinking you're running into sc->file_is_tiny
> > situations, meaning remaining file pages alone are not enough to
> > restore watermarks anymore. Is that possible?
>
> Yes DEACTIVATE_ANON is enabling the file_is_tiny case in shrink_node(). That is what im trying to prevent in the swappiness=0 case.
>

Can you please explain how DEACTIVATE_ANON is enabling the file_is_tiny case?