From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx108.postini.com [74.125.245.108]) by kanga.kvack.org (Postfix) with SMTP id BF8F56B00F2 for ; Mon, 19 Mar 2012 08:21:11 -0400 (EDT) Message-ID: <1332159657.18960.321.camel@twins> Subject: Re: [RFC][PATCH 00/26] sched/numa From: Peter Zijlstra Date: Mon, 19 Mar 2012 13:20:57 +0100 In-Reply-To: <4F671B90.3010209@redhat.com> References: <20120316144028.036474157@chello.nl> <4F670325.7080700@redhat.com> <1332155527.18960.292.camel@twins> <4F671B90.3010209@redhat.com> 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: Avi Kivity Cc: Linus Torvalds , Andrew Morton , Thomas Gleixner , Ingo Molnar , Paul Turner , Suresh Siddha , Mike Galbraith , "Paul E. McKenney" , Lai Jiangshan , Dan Smith , Bharata B Rao , Lee Schermerhorn , Andrea Arcangeli , Rik van Riel , Johannes Weiner , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Mon, 2012-03-19 at 13:42 +0200, Avi Kivity wrote: > It's the standard space/time tradeoff. Once solution wants more > storage, the other wants more faults. >=20 > Note scanners can use A/D bits which are cheaper than faults. I'm not convinced.. the scanner will still consume time even if the system is perfectly balanced -- it has to in order to determine this. So sure, A/D/other page table magic can make scanners faster than faults however you only need faults when you're actually going to migrate a task. Whereas you always need to scan, even in the stable state. So while the per-instance times might be in favour of scanning, I'm thinking the accumulated time is in favour of faults. -- 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