From: David Rientjes <rientjes@google.com>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
Michal Hocko <mhocko@kernel.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [patch] mm, oom: prevent soft lockup on memcg oom for UP systems
Date: Mon, 16 Mar 2020 21:09:48 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.21.2003162107580.97351@chino.kir.corp.google.com> (raw)
In-Reply-To: <202003170318.02H3IpSx047471@www262.sakura.ne.jp>
On Tue, 17 Mar 2020, Tetsuo Handa wrote:
> > if (!fatal_signal_pending(current))
> > schedule_timeout_killable(1);
> >
> > So we don't have this reliance on all other memory chargers to yield when
> > their charge fails and there is no delay for victims themselves.
>
> I see. You want below functions for environments where current thread can
> fail to resume execution for long if current thread once reschedules (e.g.
> UP kernel, many threads contended on one CPU).
>
> /*
> * Give other threads CPU time, unless current thread was already killed.
> * Used when we prefer killed threads to continue execution (in a hope that
> * killed threads terminate quickly) over giving other threads CPU time.
> */
> signed long __sched schedule_timeout_killable_expedited(signed long timeout)
> {
> if (unlikely(fatal_signal_pending(current)))
> return timeout;
> return schedule_timeout_killable(timeout);
> }
>
I simply want the
if (!fatal_signal_pending(current))
schedule_timeout_killable(1);
after dropping oom_lock because I don't know that a generic function would
be useful outside of this single place. If it becomes a regular pattern,
for whatever reason, I think we can consider a new schedule_timeout
variant.
> /*
> * Latency reduction via explicit rescheduling in places that are safe,
> * but becomes no-op if current thread was already killed. Used when we
> * prefer killed threads to continue execution (in a hope that killed
> * threads terminate quickly) over giving other threads CPU time.
> */
> int cond_resched_expedited(void)
> {
> if (unlikely(fatal_signal_pending(current)))
> return 0;
> return cond_resched();
> }
>
> >
> > [ I'll still propose my change that adds cond_resched() to
> > shrink_node_memcgs() because we can see need_resched set for a
> > prolonged period of time without scheduling. ]
>
> As long as there is schedule_timeout_killable(), I'm fine with adding
> cond_resched() in other places.
>
Sounds good, thanks Tetsuo.
next prev parent reply other threads:[~2020-03-17 4:09 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-10 21:39 [patch] mm, oom: prevent soft lockup on memcg oom for UP systems David Rientjes
2020-03-10 22:05 ` Tetsuo Handa
2020-03-10 22:55 ` David Rientjes
2020-03-11 9:34 ` Tetsuo Handa
2020-03-11 19:38 ` David Rientjes
2020-03-11 22:04 ` Tetsuo Handa
2020-03-11 22:14 ` David Rientjes
2020-03-12 0:12 ` Tetsuo Handa
2020-03-12 18:07 ` David Rientjes
2020-03-12 22:32 ` Andrew Morton
2020-03-16 9:31 ` Michal Hocko
2020-03-16 10:04 ` Tetsuo Handa
2020-03-16 10:14 ` Michal Hocko
2020-03-13 0:15 ` Tetsuo Handa
2020-03-13 22:01 ` David Rientjes
2020-03-13 23:15 ` Tetsuo Handa
2020-03-13 23:32 ` Tetsuo Handa
2020-03-16 23:59 ` David Rientjes
2020-03-17 3:18 ` Tetsuo Handa
2020-03-17 4:09 ` David Rientjes [this message]
2020-03-18 0:55 ` [patch v2] " David Rientjes
2020-03-18 9:42 ` Michal Hocko
2020-03-18 21:40 ` David Rientjes
2020-03-18 22:03 ` [patch v3] " David Rientjes
2020-03-19 7:09 ` Michal Hocko
2020-03-12 4:23 ` [patch] " Tetsuo Handa
2020-03-10 22:10 ` Michal Hocko
2020-03-10 23:02 ` David Rientjes
2020-03-11 8:27 ` Michal Hocko
2020-03-11 19:45 ` David Rientjes
2020-03-12 8:32 ` Michal Hocko
2020-03-12 18:20 ` David Rientjes
2020-03-12 20:16 ` Michal Hocko
2020-03-16 9:32 ` Michal Hocko
2020-03-11 0:18 ` Andrew Morton
2020-03-11 0:34 ` David Rientjes
2020-03-11 8:36 ` Michal Hocko
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