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From: Shakeel Butt <shakeelb@google.com>
To: Ivan Babrou <ivan@cloudflare.com>
Cc: "Daniel Dao" <dqminh@cloudflare.com>,
	kernel-team <kernel-team@cloudflare.com>,
	"Linux MM" <linux-mm@kvack.org>,
	"Johannes Weiner" <hannes@cmpxchg.org>,
	"Roman Gushchin" <guro@fb.com>, "Feng Tang" <feng.tang@intel.com>,
	"Michal Hocko" <mhocko@kernel.org>,
	"Hillf Danton" <hdanton@sina.com>,
	"Michal Koutný" <mkoutny@suse.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Linus Torvalds" <torvalds@linux-foundation.org>
Subject: Re: Regression in workingset_refault latency on 5.15
Date: Fri, 25 Feb 2022 09:22:20 -0800	[thread overview]
Message-ID: <CALvZod7_C0EXQQ0cibeQw3_G32KH0w7cWY7eigQyTLZLeoec9Q@mail.gmail.com> (raw)
In-Reply-To: <CABWYdi0=_c0VLSBj7RN+Hu9E2FwenqpF-PdLwzp1aWq0fwtmBw@mail.gmail.com>

On Fri, Feb 25, 2022 at 9:09 AM Ivan Babrou <ivan@cloudflare.com> wrote:
>
> On Fri, Feb 25, 2022 at 2:23 AM Daniel Dao <dqminh@cloudflare.com> wrote:
> > I think this looks good so far.
>
> I compared a flamegraph before to a flamegraph after (10s @ 99Hz on
> 96-core CPU evenly loaded to ~75% in both cases).
>
> Before: 1.4% spent in workingset_refault.
> After: 0.5% spent in flush_memcg_stats_dwork.
>
> The latter is all in kworkers (as expected), while the former is
> spread across IO active tasks.
>
> This seems like a great first step that should be merged on its own.
> It would be good to also do something to improve the CPU time spent in
> delayed work, if possible, as 0.5% of on-CPU time is not a negligible
> amount.

I will send the official async patch soon and I agree that we need to
improve rstat flush infrastructure as well but that would need more
thought and time.


  reply	other threads:[~2022-02-25 17:22 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-23 13:51 Regression in workingset_refault latency on 5.15 Daniel Dao
2022-02-23 15:57 ` Shakeel Butt
2022-02-23 16:00   ` Shakeel Butt
2022-02-23 17:07     ` Daniel Dao
2022-02-23 17:36       ` Shakeel Butt
2022-02-23 19:28         ` Ivan Babrou
2022-02-23 20:28           ` Shakeel Butt
2022-02-23 21:16             ` Ivan Babrou
2022-02-24 14:46               ` Daniel Dao
2022-02-24 16:58                 ` Shakeel Butt
2022-02-24 17:34                   ` Daniel Dao
2022-02-24 18:00                     ` Shakeel Butt
2022-02-24 18:52                       ` Shakeel Butt
2022-02-25 10:23                         ` Daniel Dao
2022-02-25 17:08                           ` Ivan Babrou
2022-02-25 17:22                             ` Shakeel Butt [this message]
2022-02-25 18:03                             ` Michal Koutný
2022-02-25 18:08                               ` Ivan Babrou
2022-02-28 23:09                                 ` Shakeel Butt
2022-02-28 23:34                                   ` Ivan Babrou
2022-02-28 23:43                                     ` Shakeel Butt
2022-03-02  0:48                                     ` Ivan Babrou
2022-03-02  2:50                                       ` Shakeel Butt
2022-03-02  3:40                                         ` Ivan Babrou
2022-03-02 22:33                                           ` Ivan Babrou
2022-03-03  2:32                                             ` Shakeel Butt
2022-03-03  2:35                                             ` Shakeel Butt
2022-03-04  0:21                                               ` Ivan Babrou
2022-03-04  1:05                                                 ` Shakeel Butt
2022-03-04  1:12                                                   ` Ivan Babrou
2022-03-02 11:49                                         ` Frank Hofmann
2022-03-02 15:52                                           ` Shakeel Butt
2022-03-02 10:08                                       ` Michal Koutný
2022-03-02 15:53                                         ` Shakeel Butt
2022-03-02 17:28                                           ` Ivan Babrou
2022-02-24  9:22 ` Thorsten Leemhuis
2022-04-11 10:17   ` Regression in workingset_refault latency on 5.15 #forregzbot Thorsten Leemhuis
2022-05-16 12:51     ` Thorsten Leemhuis

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