From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752344AbZHJIgK (ORCPT ); Mon, 10 Aug 2009 04:36:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752181AbZHJIgK (ORCPT ); Mon, 10 Aug 2009 04:36:10 -0400 Received: from e28smtp02.in.ibm.com ([59.145.155.2]:58011 "EHLO e28smtp02.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752152AbZHJIgI (ORCPT ); Mon, 10 Aug 2009 04:36:08 -0400 Date: Mon, 10 Aug 2009 14:06:02 +0530 From: Balbir Singh To: KAMEZAWA Hiroyuki Cc: Andrew Morton , andi.kleen@intel.com, Prarit Bhargava , KOSAKI Motohiro , "lizf@cn.fujitsu.com" , "menage@google.com" , Pavel Emelianov , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" Subject: Re: Help Resource Counters Scale Better (v3) Message-ID: <20090810083602.GA7176@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <20090807221238.GJ9686@balbir.in.ibm.com> <39eafe409b85053081e9c6826005bb06.squirrel@webmail-b.css.fujitsu.com> <20090808060531.GL9686@balbir.in.ibm.com> <99f2a13990d68c34c76c33581949aefd.squirrel@webmail-b.css.fujitsu.com> <20090809121530.GA5833@balbir.in.ibm.com> <20090810093229.10db7185.kamezawa.hiroyu@jp.fujitsu.com> <20090810053025.GC5257@balbir.in.ibm.com> <20090810144559.ac5a3499.kamezawa.hiroyu@jp.fujitsu.com> <20090810152205.d37d8e2f.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20090810152205.d37d8e2f.kamezawa.hiroyu@jp.fujitsu.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * KAMEZAWA Hiroyuki [2009-08-10 15:22:05]: > On Mon, 10 Aug 2009 14:45:59 +0900 > KAMEZAWA Hiroyuki wrote: > > > > Do you agree? > > > > Ok. Config is enough at this stage. > > > > The last advice for merge is, it's better to show the numbers or > > ask someone who have many cpus to measure benefits. Then, Andrew can > > know how this is benefical. > > (My box has 8 cpus. But maybe your IBM collaegue has some bigger one) > > > > In my experience (in my own old trial), > > - lock contention itself is low. not high. > > - but cacheline-miss, pingpong is very very frequent. > > > > Then, this patch has some benefit logically but, in general, > > File-I/O, swapin-swapout, page-allocation/initalize etc..dominates > > the performance of usual apps. You'll have to be careful to select apps > > to measure the benfits of this patch by application performance. > > (And this is why I don't feel so much emergency as you do) > > > > Why I say "I want to see the numbers" again and again is that > this is performance improvement with _bad side effect_. > If this is an emergent trouble, and need fast-track, which requires us > "fix small problems later", plz say so. > OK... I finally got a bigger machine (24 CPUs). I ran a simple program called parallel_pagefault, which does pagefault's in parallel (runs on every other CPU) and allocates 10K pages and touches the data allocated, unmaps and repeats the process. I ran the program for 300 seconds. With the patch, I was able to fault in twice the number of pages as I was able to without the patch. I used perf tool from tools/perf in the kernel With patch Performance counter stats for '/home/balbir/parallel_pagefault': 7188177.405648 task-clock-msecs # 23.926 CPUs 423130 context-switches # 0.000 M/sec 210 CPU-migrations # 0.000 M/sec 49851597 page-faults # 0.007 M/sec 5900210219604 cycles # 820.821 M/sec 424658049425 instructions # 0.072 IPC 7867744369 cache-references # 1.095 M/sec 2882370051 cache-misses # 0.401 M/sec 300.431591843 seconds time elapsed Without Patch Performance counter stats for '/home/balbir/parallel_pagefault': 7192804.124144 task-clock-msecs # 23.937 CPUs 424691 context-switches # 0.000 M/sec 267 CPU-migrations # 0.000 M/sec 28498113 page-faults # 0.004 M/sec 5826093739340 cycles # 809.989 M/sec 408883496292 instructions # 0.070 IPC 7057079452 cache-references # 0.981 M/sec 3036086243 cache-misses # 0.422 M/sec 300.485365680 seconds time elapsed -- Balbir