From: Chris Down <chris@chrisdown.name>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.com>, Roman Gushchin <guro@fb.com>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH] mm: memcontrol: don't count limit-setting reclaim as memory pressure
Date: Tue, 28 Jul 2020 20:44:47 +0100 [thread overview]
Message-ID: <20200728194447.GB196042@chrisdown.name> (raw)
In-Reply-To: <20200728135210.379885-2-hannes@cmpxchg.org>
Johannes Weiner writes:
>When an outside process lowers one of the memory limits of a cgroup
>(or uses the force_empty knob in cgroup1), direct reclaim is performed
>in the context of the write(), in order to directly enforce the new
>limit and have it being met by the time the write() returns.
>
>Currently, this reclaim activity is accounted as memory pressure in
>the cgroup that the writer(!) belongs to. This is unexpected. It
>specifically causes problems for senpai
>(https://github.com/facebookincubator/senpai), which is an agent that
>routinely adjusts the memory limits and performs associated reclaim
>work in tens or even hundreds of cgroups running on the host. The
>cgroup that senpai is running in itself will report elevated levels of
>memory pressure, even though it itself is under no memory shortage or
>any sort of distress.
>
>Move the psi annotation from the central cgroup reclaim function to
>callsites in the allocation context, and thereby no longer count any
>limit-setting reclaim as memory pressure. If the newly set limit
>causes the workload inside the cgroup into direct reclaim, that of
>course will continue to count as memory pressure.
Seems totally reasonable, and the patch looks fine too.
>Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Chris Down <chris@chrisdown.name>
next prev parent reply other threads:[~2020-07-28 19:44 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-28 13:52 [PATCH] mm: memcontrol: don't count limit-setting reclaim as memory pressure Johannes Weiner
2020-07-28 15:03 ` Shakeel Butt
2020-07-28 18:53 ` Roman Gushchin
2020-07-28 19:44 ` Chris Down [this message]
2020-07-30 12:00 ` Michal Hocko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200728194447.GB196042@chrisdown.name \
--to=chris@chrisdown.name \
--cc=akpm@linux-foundation.org \
--cc=cgroups@vger.kernel.org \
--cc=guro@fb.com \
--cc=hannes@cmpxchg.org \
--cc=kernel-team@fb.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@suse.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).