From: Shakeel Butt <shakeelb@google.com>
To: Nico Pache <npache@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Linux MM <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Rafael Aquini <aquini@redhat.com>, Waiman Long <llong@redhat.com>,
Michal Hocko <mhocko@suse.com>,
hakavlad@inbox.lv
Subject: Re: [PATCH v3] vm_swappiness=0 should still try to avoid swapping anon memory
Date: Tue, 10 Aug 2021 15:29:14 -0700 [thread overview]
Message-ID: <CALvZod44ge5Ny8y5xpW4YUjUSAvnU0rR=b+xyMFjAt_oOUtkBg@mail.gmail.com> (raw)
In-Reply-To: <cbdbeae9-010e-ca11-eeab-44fa7d78c83a@redhat.com>
On Tue, Aug 10, 2021 at 3:16 PM Nico Pache <npache@redhat.com> wrote:
>
>
>
> On 8/10/21 5:17 PM, Shakeel Butt wrote:
> > On Tue, Aug 10, 2021 at 12:24 PM Nico Pache <npache@redhat.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?
>
>
> You're right. Just did a second pass... I misinterpreted the assignment to
> file_is_tiny. This is not the case that is causing the issue. So back to the
> SCAN_FRACT case. From my testing the refaulting still seems to be causing the
> issue; however, to your point in earlier discussions, if swappiness=0 then the
> get_scan_count *should* be 0.
> So my patch does solve the issue by preventing the shrink_list from deactivating
> the anon, but it may be hiding some other issue that is the ultimate cause.
>
Yes, I am suspecting the same. BTW which kernel version are you testing with?
next prev parent reply other threads:[~2021-08-10 22:29 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-09 22:37 [PATCH v3] vm_swappiness=0 should still try to avoid swapping anon memory Nico Pache
2021-08-10 15:27 ` Johannes Weiner
2021-08-10 19:24 ` Nico Pache
2021-08-10 21:17 ` Shakeel Butt
2021-08-10 22:16 ` Nico Pache
2021-08-10 22:29 ` Shakeel Butt [this message]
2021-08-10 21:16 ` Shakeel Butt
2021-08-10 15:37 ` Waiman Long
2022-04-19 18:11 ` Nico Pache
2022-04-19 18:46 ` Johannes Weiner
2022-04-19 19:37 ` Nico Pache
2022-04-19 23:54 ` Nico Pache
2022-04-20 14:01 ` Johannes Weiner
2022-04-20 17:34 ` Nico Pache
2022-04-20 18:44 ` Johannes Weiner
2022-04-21 16:21 ` Nico Pache
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