From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id F0C82900194 for ; Thu, 23 Jun 2011 10:10:14 -0400 (EDT) Received: by bwz17 with SMTP id 17so2334711bwz.14 for ; Thu, 23 Jun 2011 07:10:11 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20110623134850.GK31593@tiehlicka.suse.cz> References: <20110616124730.d6960b8b.kamezawa.hiroyu@jp.fujitsu.com> <20110616125741.c3d6a802.kamezawa.hiroyu@jp.fujitsu.com> <20110623134850.GK31593@tiehlicka.suse.cz> Date: Thu, 23 Jun 2011 23:10:11 +0900 Message-ID: Subject: Re: [PATCH 7/7] memcg: proportional fair vicitm node selection From: Hiroyuki Kamezawa Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: KAMEZAWA Hiroyuki , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "akpm@linux-foundation.org" , "nishimura@mxp.nes.nec.co.jp" , "bsingharora@gmail.com" , Ying Han , "hannes@cmpxchg.org" 2011/6/23 Michal Hocko : > On Thu 16-06-11 12:57:41, KAMEZAWA Hiroyuki wrote: >> From 4fbd49697456c227c86f1d5b46f2cd2169bf1c5b Mon Sep 17 00:00:00 2001 >> From: KAMEZAWA Hiroyuki >> Date: Thu, 16 Jun 2011 11:25:23 +0900 >> Subject: [PATCH 7/7] memcg: proportional fair node vicitm selection >> >> commit 889976 implements a round-robin scan of numa nodes for >> LRU scanning of memcg at hitting limit. >> But, round-robin is not very good. >> >> This patch implements a proportionally fair victim selection of nodes >> rather than round-robin. The logic is fair against each node's weight. >> >> Each node's weight is calculated periodically and we build an node's >> scheduling entity as >> >> =A0 =A0 =A0total_ticket =3D 0; >> =A0 =A0 =A0for_each_node(node) >> =A0 =A0 =A0 node->ticket_start =3D =A0total_ticket; >> =A0 =A0 =A0 =A0 node->ticket_end =A0 =3D =A0total_ticket + this_node's_w= eight() >> =A0 =A0 =A0 =A0 total_ticket =3D node->ticket_end; >> >> Then, each nodes has some amounts of tickets in proportion to its own we= ight. >> >> At selecting victim, a random number is selected and the node which cont= ains >> the random number in [ticket_start, ticket_end) is selected as vicitm. >> This is a lottery scheduling algorithm. >> >> For quick search of victim, this patch uses bsearch(). >> >> Test result: >> =A0 on 8cpu box with 2 nodes. >> =A0 limit memory to be 300MB and run httpd for 4096files/600MB working s= et. >> =A0 do (normalized) random access by apache-bench and see scan_stat. >> =A0 The test makes 40960 request. and see scan_stat. >> =A0 (Because a httpd thread just use 10% cpu, the number of threads will >> =A0 =A0not be balanced between nodes. Then, file caches will not be bala= nced >> =A0 =A0between nodes.) > > Have you also tried to test with balanced nodes? I mean, is there any > measurable overhead? > Not enough yet. I checked OOM trouble this week :). I may need to make another fake_numa setup + cpuset to measurements. In usual path, new overhead is random32() and bsearch(). I'll do some. Thanks, -Kame -- 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