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From: Hillf Danton <hdanton@sina.com>
To: Tejun Heo <tj@kernel.org>
Cc: "Shakeel Butt" <shakeelb@google.com>,
	"Johannes Weiner" <hannes@cmpxchg.org>,
	"Muchun Song" <songmuchun@bytedance.com>,
	"Michal Hocko" <mhocko@kernel.org>,
	"Roman Gushchin" <guro@fb.com>,
	"Michal Koutný" <mkoutny@suse.com>,
	"Huang Ying" <ying.huang@intel.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	cgroups@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] memcg: periodically flush the memcg stats
Date: Sat,  5 Jun 2021 15:43:30 +0800	[thread overview]
Message-ID: <20210605074331.6952-1-hdanton@sina.com> (raw)
In-Reply-To: <YLriZxiWo+2hMI7g@slm.duckdns.org>

On Fri, 4 Jun 2021 22:33:11 -0400 Tejun Heo wrote:
>On Sat, Jun 05, 2021 at 09:54:21AM +0800, Hillf Danton wrote:
>> The cond_resched() in cgroup_rstat_flush_locked() matches its appearence in
>> your post [1]. So does unbound IMHO.
>
>Ah yeah, this either needs CPU_INTENSIVE or UNBOUND, prolly the latter is
>better.
>
>> And the short stuff [2] looks to me like it is incorrect to queue a work
>> acquiring mutex lock on to the system_wq. IOW the unbound wq is the right
>> thing for any work that might sleep.
>
>This part doesn't make sense. Blocking from per-cpu workqueue is completely
>fine. What's not fine is consuming a lot of CPU cycles.

Thanks for the light on the per-cpu workqueue - it is difficult to understand
that short stuff without it.

Hillf


      parent reply	other threads:[~2021-06-05  7:44 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-04  1:56 [PATCH 1/2] memcg: switch lruvec stats to rstat Shakeel Butt
2021-06-04  1:56 ` Shakeel Butt
2021-06-04  1:56 ` [PATCH 2/2] memcg: periodically flush the memcg stats Shakeel Butt
2021-06-04  1:56   ` Shakeel Butt
2021-06-04  1:56   ` Shakeel Butt
2021-06-04  6:18   ` Hillf Danton
2021-06-04 12:45     ` Tejun Heo
2021-06-04 12:45       ` Tejun Heo
     [not found]     ` <20210605015421.5096-1-hdanton@sina.com>
2021-06-05  2:33       ` Tejun Heo
2021-06-05  2:33         ` Tejun Heo
2021-06-05  4:45         ` Shakeel Butt
2021-06-05  4:45           ` Shakeel Butt
2021-06-05  7:43         ` Hillf Danton [this message]

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