From: Christoph Lameter <cl@linux-foundation.org>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH 2/2] mlock use lru_add_drain_all_async()
Date: Tue, 6 Oct 2009 12:27:27 -0400 (EDT) [thread overview]
Message-ID: <alpine.DEB.1.10.0910061226300.18309@gentwo.org> (raw)
In-Reply-To: <20091006114052.5FAA.A69D9226@jp.fujitsu.com>
On Tue, 6 Oct 2009, KOSAKI Motohiro wrote:
> Suppose you have 2 cpus, cpu1 is busy doing a SCHED_FIFO-99 while(1),
> cpu0 does mlock()->lru_add_drain_all(), which does
> schedule_on_each_cpu(), which then waits for all cpus to complete the
> work. Except that cpu1, which is busy with the RT task, will never run
> keventd until the RT load goes away.
>
> This is not so much an actual deadlock as a serious starvation case.
>
> Actually, mlock() doesn't need to wait to finish lru_add_drain_all().
> Thus, this patch replace it with lru_add_drain_all_async().
Ok so this will queue up lots of events for the cpu doing a RT task. If
the RT task is continuous then they will be queued there forever?
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next prev parent reply other threads:[~2009-10-06 16:33 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-06 2:40 [PATCH 1/2] Implement lru_add_drain_all_async() KOSAKI Motohiro
2009-10-06 2:41 ` [PATCH 2/2] mlock use lru_add_drain_all_async() KOSAKI Motohiro
2009-10-06 9:08 ` Peter Zijlstra
2009-10-06 10:11 ` KOSAKI Motohiro
2009-10-06 16:27 ` Christoph Lameter [this message]
2009-10-07 3:37 ` KOSAKI Motohiro
2009-10-06 22:59 ` Ying Han
2009-10-07 3:48 ` KOSAKI Motohiro
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