From: Michal Hocko <mhocko@suse.com>
To: "Michal Koutný" <mkoutny@suse.com>
Cc: Yosry Ahmed <yosryahmed@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Shakeel Butt <shakeelb@google.com>,
Muchun Song <muchun.song@linux.dev>,
Ivan Babrou <ivan@cloudflare.com>, Tejun Heo <tj@kernel.org>,
Waiman Long <longman@redhat.com>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 3/4] mm: memcg: let non-unified root stats flushes help unified flushes
Date: Mon, 4 Sep 2023 17:41:10 +0200 [thread overview]
Message-ID: <ZPX6luPGqypp68+L@dhcp22.suse.cz> (raw)
In-Reply-To: <6tne52ip62ucev7nmnim3m7fhcydnwcytyxynrlxxgaf4cbqea@r4hec425izap>
On Mon 04-09-23 17:29:14, Michal Koutny wrote:
> Hello.
>
> On Mon, Sep 04, 2023 at 04:50:15PM +0200, Michal Hocko <mhocko@suse.com> wrote:
> > I have hard time to follow why we really want/need this. Does this cause
> > any observable changes to the behavior?
>
> Behavior change depends on how much userspace triggers the root memcg
> flush, from nothing to effectively offloading flushing to userspace tasks.
> (Theory^^^)
>
> It keeps stats_flush_threshold up to date representing global error
> estimate so that error-tolerant readers may save their time and it keeps
> the reasoning about the stats_flush_threshold effect simple.
So it also creates an undocumented but userspace visible behavior.
Something that userspace might start depending on, right?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2023-09-04 15:41 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-31 16:56 [PATCH v4 0/4] memcg: non-unified flushing for userspace stats Yosry Ahmed
2023-08-31 16:56 ` [PATCH v4 1/4] mm: memcg: properly name and document unified stats flushing Yosry Ahmed
2023-09-04 14:44 ` Michal Hocko
2023-09-05 15:55 ` Yosry Ahmed
2023-08-31 16:56 ` [PATCH v4 2/4] mm: memcg: add a helper for non-unified " Yosry Ahmed
2023-09-04 14:45 ` Michal Hocko
2023-08-31 16:56 ` [PATCH v4 3/4] mm: memcg: let non-unified root stats flushes help unified flushes Yosry Ahmed
2023-09-04 14:50 ` Michal Hocko
2023-09-04 15:29 ` Michal Koutný
2023-09-04 15:41 ` Michal Hocko [this message]
2023-09-05 14:10 ` Michal Koutný
2023-09-05 15:54 ` Yosry Ahmed
2023-09-05 16:07 ` Michal Koutný
2023-09-12 11:03 ` Michal Hocko
2023-08-31 16:56 ` [PATCH v4 4/4] mm: memcg: use non-unified stats flushing for userspace reads Yosry Ahmed
2023-09-04 15:15 ` Michal Hocko
2023-09-05 15:57 ` Yosry Ahmed
2023-09-08 0:52 ` Wei Xu
2023-09-08 1:02 ` Ivan Babrou
2023-09-08 1:11 ` Yosry Ahmed
2023-09-11 13:11 ` Michal Hocko
2023-09-11 19:15 ` Wei Xu
2023-09-11 19:34 ` Michal Hocko
2023-09-11 20:01 ` Wei Xu
2023-09-11 20:21 ` Tejun Heo
2023-09-11 20:28 ` Yosry Ahmed
2023-09-12 11:03 ` Michal Hocko
2023-09-12 11:09 ` Yosry Ahmed
2023-08-31 17:18 ` [PATCH v4 0/4] memcg: non-unified flushing for userspace stats Waiman Long
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