From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id D1F176B007E for ; Tue, 8 Sep 2009 10:04:44 -0400 (EDT) Received: from localhost (smtp.ultrahosting.com [127.0.0.1]) by smtp.ultrahosting.com (Postfix) with ESMTP id D293182C38A for ; Tue, 8 Sep 2009 10:05:33 -0400 (EDT) Received: from smtp.ultrahosting.com ([74.213.174.253]) by localhost (smtp.ultrahosting.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id FPYSWwUADe3b for ; Tue, 8 Sep 2009 10:05:33 -0400 (EDT) Received: from V090114053VZO-1 (unknown [74.213.171.31]) by smtp.ultrahosting.com (Postfix) with ESMTP id 0011882C3AE for ; Tue, 8 Sep 2009 10:05:28 -0400 (EDT) Date: Tue, 8 Sep 2009 10:03:42 -0400 (EDT) From: Christoph Lameter Subject: Re: [rfc] lru_add_drain_all() vs isolation In-Reply-To: <1252411520.7746.68.camel@twins> Message-ID: References: <20090908190148.0CC9.A69D9226@jp.fujitsu.com> <1252405209.7746.38.camel@twins> <20090908193712.0CCF.A69D9226@jp.fujitsu.com> <1252411520.7746.68.camel@twins> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Peter Zijlstra Cc: KOSAKI Motohiro , Mike Galbraith , Ingo Molnar , linux-mm , Oleg Nesterov , lkml List-ID: On Tue, 8 Sep 2009, Peter Zijlstra wrote: > This is about avoiding work when there is non, clearly when an > application does use the kernel it creates work. Hmmm. The lru draining in page migration is to reduce the number of pages that are not on the lru to increase the chance of page migration to be successful. A page on a per cpu list cannot be drained. Reducing the number of cpus where we perform the drain results in increased likelyhood that we cannot migrate a page because its on the per cpu lists of a cpu not covered. On the other hand if the cpu is offline then we know that it has no per cpu pages. That is why I found the idea of the OFFLINE scheduler attractive. -- 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/ . Don't email: email@kvack.org