From: Johannes Weiner <hannes@cmpxchg.org>
To: Michal Hocko <mhocko@suse.com>
Cc: cuishiwei <cuishw@inspur.com>,
akpm@linux-foundation.org, axelrasmussen@google.com,
yuanchu@google.com, weixugc@google.com, david@redhat.com,
zhengqi.arch@bytedance.com, shakeel.butt@linux.dev,
lorenzo.stoakes@oracle.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] disable demotion during memory reclamation
Date: Tue, 9 Sep 2025 15:45:31 +0100 [thread overview]
Message-ID: <20250909144531.GA1474@cmpxchg.org> (raw)
In-Reply-To: <aL_aA2HKjfmwBaJ-@tiehlicka>
On Tue, Sep 09, 2025 at 09:40:51AM +0200, Michal Hocko wrote:
> On Tue 09-09-25 09:21:41, cuishiwei wrote:
> > When a memory cgroup exceeds its memory limit, the system reclaims
> > its cold memory.However, if /sys/kernel/mm/numa/demotion_enabled is
> > set to 1, memory on fast memory nodes will also be demoted to slow
> > memory nodes.
> >
> > This demotion contradicts the goal of reclaiming cold memory within
> > the memcg.At this point, demoting cold memory from fast to slow nodes
> > is pointless;it doesn't reduce the memcg's memory usage. Therefore,
> > we should set no_demotion when reclaiming memory in a memcg.
>
> We have discussed this in the past and it is my recollection that we
> have concluded that demotion is a part of proper aging and therefore it
> should be done during the limit reclaim.
Yes, thanks. This is intentional. Please see 3f1509c57b1b ("Revert
"mm/vmscan: never demote for memcg reclaim"") for more details.
next prev parent reply other threads:[~2025-09-09 14:45 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-09 1:21 [PATCH] disable demotion during memory reclamation cuishiwei
2025-09-09 1:36 ` Andrew Morton
2025-09-09 2:40 ` cuishiwei
2025-09-09 7:40 ` Michal Hocko
2025-09-09 14:45 ` Johannes Weiner [this message]
2025-09-10 6:36 ` cuishiwei
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=20250909144531.GA1474@cmpxchg.org \
--to=hannes@cmpxchg.org \
--cc=akpm@linux-foundation.org \
--cc=axelrasmussen@google.com \
--cc=cuishw@inspur.com \
--cc=david@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=lorenzo.stoakes@oracle.com \
--cc=mhocko@suse.com \
--cc=shakeel.butt@linux.dev \
--cc=weixugc@google.com \
--cc=yuanchu@google.com \
--cc=zhengqi.arch@bytedance.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.