From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx163.postini.com [74.125.245.163]) by kanga.kvack.org (Postfix) with SMTP id AD4CA6B00EB for ; Tue, 15 May 2012 10:45:26 -0400 (EDT) Message-ID: <1337093115.27694.51.camel@twins> Subject: Re: Allow migration of mlocked page? From: Peter Zijlstra Date: Tue, 15 May 2012 16:45:15 +0200 In-Reply-To: References: <4FAC9786.9060200@kernel.org> <20120511131404.GQ11435@suse.de> <4FB08920.4010001@kernel.org> <20120514133944.GF29102@suse.de> <4FB1BC3E.3070107@kernel.org> <1337079974.27694.36.camel@twins> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: quoted-printable Mime-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: KOSAKI Motohiro , Minchan Kim , Mel Gorman , Johannes Weiner , Rik van Riel , Andrew Morton , Andrea Arcangeli , KAMEZAWA Hiroyuki , "linux-mm@kvack.org" , tglx@linutronix.de, Ingo Molnar , Theodore Ts'o On Tue, 2012-05-15 at 09:12 -0500, Christoph Lameter wrote: > On Tue, 15 May 2012, Peter Zijlstra wrote: >=20 > > So yes, page migration is a 'serious' problem, but only because the way > > its implemented is sub-optimal. >=20 > 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 n= o > low-latency responses are needed by the app. This means during setup or > special processing times (maybe after some action was completed). >=20 > 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. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org