From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: tj@kernel.org
Cc: mhocko@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: Fri, 1 Sep 2017 23:29:19 +0900 [thread overview]
Message-ID: <201709012329.EJF00526.MFFQtOVJFHOSLO@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <20170901134748.GC1599492@devbig577.frc2.facebook.com>
Tejun Heo wrote:
> On Fri, Sep 01, 2017 at 07:07:25AM +0900, Tetsuo Handa wrote:
> > cond_resched() from !PF_WQ_WORKER threads is sufficient for PF_WQ_WORKER threads to run.
> > But cond_resched() is not sufficient for rescuer threads to start processing a pending work.
> > An explicit scheduling (e.g. schedule_timeout_*()) by PF_WQ_WORKER threads is needed for
> > rescuer threads to start processing a pending work.
>
> I'm not even sure this is the case. Unless I'm mistaken, in your
> workqueue dumps, the available workers couldn't even leave idle which
> means that they likely didn't get scheduled at all. It looks like
> genuine multi minute starvation by competing direct reclaims. What's
> the load number like while these events are in progress?
I don't know the load number because the system is unresponsive due to global
OOM. All information I can collect is via printk() from SysRq. But I guess that
it is genuine multi minute starvation by competing direct reclaims, for
I ran 1024 threads on 4 or 8 CPUs / 4GB RAM / no swap in order to test heavy
memory pressure situation where WQ_MEM_RECLAIM mm_percpu_wq work will stay
pending when I check for SysRq-t.
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next prev parent reply other threads:[~2017-09-01 14:29 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 ` [PATCH] mm: Use WQ_HIGHPRI for mm_percpu_wq 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
2017-08-31 22:07 ` Tetsuo Handa
2017-09-01 13:47 ` Tejun Heo
2017-09-01 14:29 ` Tetsuo Handa [this message]
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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