From: Michal Hocko <mhocko@suse.com>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Roman Gushchin <guro@fb.com>,
David Rientjes <rientjes@google.com>,
Shakeel Butt <shakeelb@google.com>,
linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] mm, oom: simplify task's refcount handling
Date: Wed, 24 Jul 2019 10:07:26 +0200 [thread overview]
Message-ID: <20190724080726.GA5584@dhcp22.suse.cz> (raw)
In-Reply-To: <d6aebef5-60f8-a61c-0564-5bb4595e8e2c@i-love.sakura.ne.jp>
On Wed 24-07-19 16:37:35, Tetsuo Handa wrote:
> On 2019/07/24 15:41, Michal Hocko wrote:
[...]
> > That being said, I do not think this patch gives any improvement.
> >
>
> This patch avoids RCU during select_bad_process().
It just shifts where the RCU is taken. Do you have any numbers to show
that this is an improvement? Basically the only potentially expensive
thing down the oom_evaluate_task that I can see is the task_lock but I
am not aware of a single report that this would be a contributor for RCU
stalls. I can be proven wrong but
> This patch allows
> possibility of doing reschedulable things there; e.g. directly reaping
> only a portion of OOM victim's memory rather than wasting CPU resource
> by spinning until MMF_OOM_SKIP is set by the OOM reaper.
We have been through direct oom reaping before and I haven't changed my
possition there. It is just too tricky to be worth it.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2019-07-24 8:07 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-24 3:54 Tetsuo Handa
2019-07-24 6:41 ` Michal Hocko
2019-07-24 7:37 ` Tetsuo Handa
2019-07-24 8:07 ` Michal Hocko [this message]
2019-07-26 3:17 ` Tetsuo Handa
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