Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759459Ab1FWOKO (ORCPT ); Thu, 23 Jun 2011 10:10:14 -0400 Received: from mail-bw0-f46.google.com ([209.85.214.46]:64901 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753547Ab1FWOKM convert rfc822-to-8bit (ORCPT ); Thu, 23 Jun 2011 10:10:12 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=SW+/LeYcVjCSWLVsCaxz0VZY69xPH0/Yx1ZwomrzDDFhgMD3l61+KLiaj81ll4boYN s0wkXeNt3XYVdn5kJXZ24I47sn5L7Az/3jipeXROZ9mrSEqUfW9Yy3zZgFYQf74SlDmH WL8pTkK4F5HNDCMfGTTZu/PmHDYDON4f2Teig= 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 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" Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2275 Lines: 57 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 >> >> ? ? ?total_ticket = 0; >> ? ? ?for_each_node(node) >> ? ? ? node->ticket_start = ?total_ticket; >> ? ? ? ? node->ticket_end ? = ?total_ticket + this_node's_weight() >> ? ? ? ? total_ticket = node->ticket_end; >> >> Then, each nodes has some amounts of tickets in proportion to its own weight. >> >> At selecting victim, a random number is selected and the node which contains >> 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: >> ? on 8cpu box with 2 nodes. >> ? limit memory to be 300MB and run httpd for 4096files/600MB working set. >> ? do (normalized) random access by apache-bench and see scan_stat. >> ? The test makes 40960 request. and see scan_stat. >> ? (Because a httpd thread just use 10% cpu, the number of threads will >> ? ?not be balanced between nodes. Then, file caches will not be balanced >> ? ?between 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 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/