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From: Shakeel Butt <shakeelb@google.com>
To: Daniel Dao <dqminh@cloudflare.com>
Cc: "Ivan Babrou" <ivan@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: Thu, 24 Feb 2022 10:00:55 -0800	[thread overview]
Message-ID: <CALvZod4Ln_Ny=OQW0DB7_arBnmjUaTLnYkn-H4BnSuw8XsMeFA@mail.gmail.com> (raw)
In-Reply-To: <CA+wXwBQ0jF0eKZ5x_TRUWmQ3fzV3J+SbBsLmxF0a-OmTVa25pA@mail.gmail.com>

On Thu, Feb 24, 2022 at 9:34 AM Daniel Dao <dqminh@cloudflare.com> wrote:
>
[...]
> > Thanks for testing. At the moment I am suspecting the async worker is
> > not getting the CPU. Can you share your CONFIG_HZ setting? Also can you
> > try the following patch and see if that helps otherwise keep halving the
> > delay (i.e. 2HZ -> HZ -> HZ/2 -> ...) and find at what value the issue
> > you are seeing get resolved?
>
> We have CONFIG_HZ=1000. We can try to increase the frequency of async flush, but
> that seems like a not great bandaid. Is it possible to remove
> mem_cgroup_flush_stats()
> from workingset_refault, or at least scope it down to some targeted cgroup so
> we don't need to flush from root with potentially large sets of
> cgroups to walk ?

I actually wanted to know what would be the good frequency of rstat
flushing for your workload. I am not planning to propose to change the
default frequency.

Anyways I am thinking of introducing mem_cgroup_flush_stats_asyn()
which will schedule flush_memcg_stats_dwork() without delay. Let me
prepare the patch based on 5.15-stable for you to test.


  reply	other threads:[~2022-02-24 18:01 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 [this message]
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
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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