Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932191Ab1FQJON (ORCPT ); Fri, 17 Jun 2011 05:14:13 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:45812 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757358Ab1FQJOJ (ORCPT ); Fri, 17 Jun 2011 05:14:09 -0400 Date: Fri, 17 Jun 2011 11:13:19 +0200 From: Ingo Molnar To: Andi Kleen Cc: Linus Torvalds , Peter Zijlstra , Tim Chen , Shaohua Li , Andrew Morton , Hugh Dickins , KOSAKI Motohiro , Benjamin Herrenschmidt , David Miller , Martin Schwidefsky , Russell King , Paul Mundt , Jeff Dike , Richard Weinberger , "Luck, Tony" , KAMEZAWA Hiroyuki , Mel Gorman , Nick Piggin , Namhyung Kim , "Shi, Alex" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , Thomas Gleixner , "Rafael J. Wysocki" Subject: Re: REGRESSION: Performance regressions from switching anon_vma->lock to mutex Message-ID: <20110617091319.GA11719@elte.hu> References: <1308169937.15315.88.camel@twins> <4DF91CB9.5080504@linux.intel.com> <1308172336.17300.177.camel@schen9-DESK> <1308173849.15315.91.camel@twins> <87ea4bd7-8b16-4b24-8fcb-d8e9b6f421ec@email.android.com> <4DF92FE1.5010208@linux.intel.com> <4DFA6442.9000103@linux.intel.com> <4DFA9EA4.4010904@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4DFA9EA4.4010904@linux.intel.com> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.3.1 -2.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1444 Lines: 43 * Andi Kleen wrote: > > I tried to send uli a patch to just add caching. No go. I sent > > *another* patch to at least make glibc use a sane interface (and > > the cache if it needs to fall back on /proc/stat for some legacy > > reason). We'll see what happens. > > FWIW a rerun with this modified LD_PRELOAD that does caching seems > to have the same performance as the version that does > sched_getaffinity. > > So you're right. Caching indeed helps and my assumption that the > child would only do it once was incorrect. You should have known that your assumption was wrong not just from a quick look at the strace output or a quick look at the glibc sources, but also because i pointed out the caching angle to you in the sysconf() discussion: http://lkml.org/lkml/2011/5/14/9 repeatedly: http://lkml.org/lkml/2011/5/17/149 and Denys Vlasenko pointed out the caching angle as well: http://lkml.org/lkml/2011/5/17/183 But you kept pushing for your new syscall for upstream integration, ignoring all contrary evidence and ignoring all contrary feedback, without even *once* checking where and how it would integrate into glibc ... Thanks, Ingo -- 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/