From: Peter Zijlstra <peterz@infradead.org>
To: Christoph Lameter <cl@linux.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
Minchan Kim <minchan@kernel.org>, Mel Gorman <mgorman@suse.de>,
Johannes Weiner <hannes@cmpxchg.org>,
Rik van Riel <riel@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
tglx@linutronix.de, Ingo Molnar <mingo@redhat.com>,
Theodore Ts'o <tytso@mit.edu>
Subject: Re: Allow migration of mlocked page?
Date: Tue, 15 May 2012 16:45:15 +0200 [thread overview]
Message-ID: <1337093115.27694.51.camel@twins> (raw)
In-Reply-To: <alpine.DEB.2.00.1205150911140.6488@router.home>
On Tue, 2012-05-15 at 09:12 -0500, Christoph Lameter wrote:
> On Tue, 15 May 2012, Peter Zijlstra wrote:
>
> > So yes, page migration is a 'serious' problem, but only because the way
> > its implemented is sub-optimal.
>
> For the low-latency cases: page migration needs to be restricted to cpus
> that are allowed to run high latency tasks or restricted to a time that no
> low-latency responses are needed by the app. This means during setup or
> special processing times (maybe after some action was completed).
>
> A random compaction run can be very bad for a latency critical section.
Yes however:
1) low latency doesn't make real-time, time bounds do.
2) the latency impact of migration can be _MUCH_ improved if someone
were to care about it.
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next prev parent reply other threads:[~2012-05-15 14:45 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-11 4:37 Allow migration of mlocked page? Minchan Kim
2012-05-11 9:20 ` Peter Zijlstra
2012-05-11 16:20 ` Christoph Lameter
2012-05-11 23:24 ` KOSAKI Motohiro
2012-05-14 13:45 ` Christoph Lameter
2012-05-14 4:13 ` Minchan Kim
2012-05-14 6:56 ` Peter Zijlstra
2012-05-14 7:37 ` Minchan Kim
2012-05-14 7:45 ` Peter Zijlstra
2012-05-14 7:49 ` Peter Zijlstra
2012-05-14 7:54 ` Minchan Kim
2012-05-14 13:47 ` Christoph Lameter
2012-05-15 1:23 ` Minchan Kim
2012-05-15 11:07 ` Peter Zijlstra
2012-05-11 13:14 ` Mel Gorman
2012-05-11 23:25 ` KOSAKI Motohiro
2012-05-14 13:32 ` Mel Gorman
2012-05-14 13:51 ` Peter Zijlstra
2012-05-14 14:01 ` Christoph Lameter
2012-05-14 14:14 ` Peter Zijlstra
2012-05-14 14:43 ` Christoph Lameter
2012-05-14 22:52 ` KOSAKI Motohiro
2012-05-14 23:04 ` Roland Dreier
2012-05-15 14:27 ` Christoph Lameter
2012-05-15 1:38 ` Minchan Kim
2012-05-14 14:08 ` Peter Zijlstra
2012-05-14 23:06 ` KOSAKI Motohiro
2012-05-15 1:35 ` Minchan Kim
2012-05-14 4:25 ` Minchan Kim
2012-05-14 13:39 ` Mel Gorman
2012-05-15 2:15 ` Minchan Kim
2012-05-15 4:33 ` KOSAKI Motohiro
2012-05-15 11:06 ` Peter Zijlstra
2012-05-15 14:12 ` Christoph Lameter
2012-05-15 14:45 ` Peter Zijlstra [this message]
2012-05-15 15:11 ` Christoph Lameter
2012-05-15 14:10 ` Christoph Lameter
2012-05-15 14:09 ` Christoph Lameter
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