From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id 7EC566B0055 for ; Mon, 10 Aug 2009 03:42:51 -0400 (EDT) Received: from d23relay01.au.ibm.com (d23relay01.au.ibm.com [202.81.31.243]) by e23smtp09.au.ibm.com (8.14.3/8.13.1) with ESMTP id n7A7f8kJ030399 for ; Mon, 10 Aug 2009 17:41:08 +1000 Received: from d23av04.au.ibm.com (d23av04.au.ibm.com [9.190.235.139]) by d23relay01.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id n7A7gkk8450980 for ; Mon, 10 Aug 2009 17:42:48 +1000 Received: from d23av04.au.ibm.com (loopback [127.0.0.1]) by d23av04.au.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n7A7gjnl021474 for ; Mon, 10 Aug 2009 17:42:46 +1000 Date: Mon, 10 Aug 2009 13:11:34 +0530 From: Balbir Singh Subject: Re: Help Resource Counters Scale Better (v3) Message-ID: <20090810074134.GA4648@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> Sender: owner-linux-mm@kvack.org 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" List-ID: * 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. > Yes, this is an emergent trouble, I've gotten reports of the lock showing up on 16 to 64 ways. > I have no objection to this approach itself because I can't think of > something better, now. percpu-counter's error tolerance is a generic > problem and we'll have to visit this anyway. > Yes, my plan is to then later add a strict/no-strict accounting layer and allow users to choose. Keep root as non-script as we don't support limit setting on root now. -- Balbir -- 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