From: Michal Hocko <mhocko@kernel.org>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: tj@kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org,
mgorman@suse.de, vbabka@suse.cz
Subject: Re: [PATCH] mm: Use WQ_HIGHPRI for mm_percpu_wq.
Date: Thu, 31 Aug 2017 17:25:23 +0200 [thread overview]
Message-ID: <20170831152523.nwdbjock6b6tams5@dhcp22.suse.cz> (raw)
In-Reply-To: <201708312352.CCC87558.OFMLOVtQOFJFHS@I-love.SAKURA.ne.jp>
On Thu 31-08-17 23:52:57, Tetsuo Handa wrote:
[...]
> So, this pending state seems to be caused by many concurrent allocations by !PF_WQ_WORKER
> threads consuming too much CPU time (because they only yield CPU time by many cond_resched()
> and one schedule_timeout_uninterruptible(1)) enough to keep schedule_timeout_uninterruptible(1)
> by PF_WQ_WORKER threads away for order of minutes. A sort of memory allocation dependency
> observable in the form of CPU time starvation for the worker to wake up.
I do not understand this. Why is cond_resched from the user context
insufficient to let runable kworkers to run?
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2017-08-31 15:25 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1503921210-4603-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp>
2017-08-28 12:10 ` Michal Hocko
2017-08-28 17:06 ` Tejun Heo
2017-08-28 22:15 ` Tetsuo Handa
2017-08-28 23:02 ` Tejun Heo
2017-08-28 23:09 ` Tejun Heo
2017-08-29 11:14 ` Tetsuo Handa
2017-08-29 14:38 ` Tejun Heo
2017-08-29 21:41 ` Tejun Heo
2017-08-30 13:51 ` Tetsuo Handa
2017-08-31 1:46 ` Tejun Heo
2017-08-31 14:52 ` Tetsuo Handa
2017-08-31 15:25 ` Michal Hocko [this message]
2017-08-31 22:07 ` Tetsuo Handa
2017-09-01 13:47 ` Tejun Heo
2017-09-01 14:29 ` Tetsuo Handa
2017-08-29 13:33 ` Michal Hocko
2017-08-29 14:33 ` Tejun Heo
2017-08-29 20:29 ` Tetsuo Handa
2017-08-30 6:40 ` Michal Hocko
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