From: Dave Chinner <david@fromorbit.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: peterz@infradead.org, Chris Down <chris@chrisdown.name>,
Waiman Long <longman@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Jonathan Corbet <corbet@lwn.net>,
Alexey Dobriyan <adobriyan@gmail.com>,
Ingo Molnar <mingo@kernel.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [RFC PATCH 0/8] memcg: Enable fine-grained per process memory control
Date: Thu, 20 Aug 2020 16:11:12 +1000 [thread overview]
Message-ID: <20200820061112.GA7728@dread.disaster.area> (raw)
In-Reply-To: <20200818125559.GP17456@casper.infradead.org>
On Tue, Aug 18, 2020 at 01:55:59PM +0100, Matthew Wilcox wrote:
> On Tue, Aug 18, 2020 at 12:04:44PM +0200, peterz@infradead.org wrote:
> > On Tue, Aug 18, 2020 at 10:27:37AM +0100, Chris Down wrote:
> > > peterz@infradead.org writes:
> > > > On Mon, Aug 17, 2020 at 10:08:23AM -0400, Waiman Long wrote:
> > > > > Memory controller can be used to control and limit the amount of
> > > > > physical memory used by a task. When a limit is set in "memory.high" in
> > > > > a v2 non-root memory cgroup, the memory controller will try to reclaim
> > > > > memory if the limit has been exceeded. Normally, that will be enough
> > > > > to keep the physical memory consumption of tasks in the memory cgroup
> > > > > to be around or below the "memory.high" limit.
> > > > >
> > > > > Sometimes, memory reclaim may not be able to recover memory in a rate
> > > > > that can catch up to the physical memory allocation rate. In this case,
> > > > > the physical memory consumption will keep on increasing.
> > > >
> > > > Then slow down the allocator? That's what we do for dirty pages too, we
> > > > slow down the dirtier when we run against the limits.
> > >
> > > We already do that since v5.4. I'm wondering whether Waiman's customer is
> > > just running with a too-old kernel without 0e4b01df865 ("mm, memcg: throttle
> > > allocators when failing reclaim over memory.high") backported.
> >
> > That commit is fundamentally broken, it doesn't guarantee anything.
> >
> > Please go read how the dirty throttling works (unless people wrecked
> > that since..).
>
> Of course they did.
>
> https://lore.kernel.org/linux-mm/ce7975cd-6353-3f29-b52c-7a81b1d07caa@kernel.dk/
Different thing. That's memory reclaim throttling, not dirty page
throttling. balance_dirty_pages() still works just fine as it does
not look at device congestion. page cleaning rate is accounted in
test_clear_page_writeback(), page dirtying rate is accounted
directly in balance_dirty_pages(). That feedback loop has not been
broken...
And I compeltely agree with Peter here - the control theory we
applied to the dirty throttling problem is still 100% valid and so
the algorithm still just works all these years later. I've only been
saying that allocation should use the same feedback model for
reclaim throttling since ~2011...
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2020-08-20 6:11 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-17 14:08 [RFC PATCH 0/8] memcg: Enable fine-grained per process memory control Waiman Long
2020-08-17 14:08 ` [RFC PATCH 1/8] memcg: Enable fine-grained control of over memory.high action Waiman Long
2020-08-17 14:30 ` Chris Down
2020-08-17 15:38 ` Waiman Long
2020-08-17 16:11 ` Chris Down
2020-08-17 16:44 ` Shakeel Butt
2020-08-17 16:56 ` Chris Down
2020-08-18 19:12 ` Waiman Long
2020-08-18 19:14 ` Waiman Long
2020-08-17 14:08 ` [RFC PATCH 2/8] memcg, mm: Return ENOMEM or delay if memcg_over_limit Waiman Long
2020-08-17 14:08 ` [RFC PATCH 3/8] memcg: Allow the use of task RSS memory as over-high action trigger Waiman Long
2020-08-17 14:08 ` [RFC PATCH 4/8] fs/proc: Support a new procfs memctl file Waiman Long
2020-08-17 14:08 ` [RFC PATCH 5/8] memcg: Allow direct per-task memory limit checking Waiman Long
2020-08-17 14:08 ` [RFC PATCH 6/8] memcg: Introduce additional memory control slowdown if needed Waiman Long
2020-08-17 14:08 ` [RFC PATCH 7/8] memcg: Enable logging of memory control mitigation action Waiman Long
2020-08-17 14:08 ` [RFC PATCH 8/8] memcg: Add over-high action prctl() documentation Waiman Long
2020-08-17 15:26 ` [RFC PATCH 0/8] memcg: Enable fine-grained per process memory control Michal Hocko
2020-08-17 15:55 ` Waiman Long
2020-08-17 19:26 ` Michal Hocko
2020-08-18 19:20 ` Waiman Long
2020-08-18 9:14 ` peterz
2020-08-18 9:26 ` Michal Hocko
2020-08-18 9:59 ` peterz
2020-08-18 10:05 ` Michal Hocko
2020-08-18 10:18 ` peterz
2020-08-18 10:30 ` Michal Hocko
2020-08-18 10:36 ` peterz
2020-08-18 13:49 ` Johannes Weiner
2020-08-21 19:37 ` Peter Zijlstra
2020-08-24 16:58 ` Johannes Weiner
2020-09-07 11:47 ` Chris Down
2020-09-09 11:53 ` Michal Hocko
2020-08-18 10:17 ` Chris Down
2020-08-18 10:26 ` peterz
2020-08-18 10:35 ` Chris Down
2020-08-23 2:49 ` Waiman Long
2020-08-18 9:27 ` Chris Down
2020-08-18 10:04 ` peterz
2020-08-18 12:55 ` Matthew Wilcox
2020-08-20 6:11 ` Dave Chinner [this message]
2020-08-18 19:30 ` Waiman Long
2020-08-18 19:27 ` Waiman Long
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=20200820061112.GA7728@dread.disaster.area \
--to=david@fromorbit.com \
--cc=adobriyan@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=cgroups@vger.kernel.org \
--cc=chris@chrisdown.name \
--cc=corbet@lwn.net \
--cc=hannes@cmpxchg.org \
--cc=juri.lelli@redhat.com \
--cc=linux-doc@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=longman@redhat.com \
--cc=mhocko@kernel.org \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=vdavydov.dev@gmail.com \
--cc=vincent.guittot@linaro.org \
--cc=willy@infradead.org \
/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).