Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934108Ab1EOWec (ORCPT ); Sun, 15 May 2011 18:34:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59229 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934091Ab1EOWeb (ORCPT ); Sun, 15 May 2011 18:34:31 -0400 Message-ID: <4DD054EF.4020300@redhat.com> Date: Sun, 15 May 2011 18:34:23 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.15) Gecko/20110307 Fedora/3.1.9-0.38.b3pre.fc13 Lightning/1.0b3pre Thunderbird/3.1.9 MIME-Version: 1.0 To: KOSAKI Motohiro CC: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, kamezawa.hiroyu@jp.fujitsu.com, minchan.kim@gmail.com Subject: Re: [PATCH 3/3] vmscan: implement swap token priority decay References: <4DCD1824.1060801@jp.fujitsu.com> <4DCD1913.2090200@jp.fujitsu.com> In-Reply-To: <4DCD1913.2090200@jp.fujitsu.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1215 Lines: 30 On 05/13/2011 07:42 AM, KOSAKI Motohiro wrote: > While testing for memcg aware swap token, I observed a swap token > was often grabbed an intermittent running process (eg init, auditd) > and they never release a token. > > Why? Currently, swap toke priority is only decreased at page fault > path. Then, if the process sleep immediately after to grab swap > token, their swap token priority never be decreased. That makes > obviously undesired result. > > This patch implement very poor (and lightweight) priority decay > mechanism. It only be affect to the above corner case and doesn't > change swap tendency workload performance (eg multi process qsbench > load) Ohhh, good catch. The original swap token algorithm did not have this problem, and I never caught the fact that the replacement (which is better in many ways) does... > Signed-off-by: KOSAKI Motohiro Reviewed-by: Rik van Riel -- All rights reversed -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/