Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756886AbZD1Ja2 (ORCPT ); Tue, 28 Apr 2009 05:30:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755404AbZD1JaM (ORCPT ); Tue, 28 Apr 2009 05:30:12 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:59906 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755238AbZD1JaL (ORCPT ); Tue, 28 Apr 2009 05:30:11 -0400 Date: Tue, 28 Apr 2009 11:29:18 +0200 From: Ingo Molnar To: Pekka Enberg Cc: Andi Kleen , Wu Fengguang , Steven Rostedt , =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker , Larry Woodman , Peter Zijlstra , Eduard - Gabriel Munteanu , Andrew Morton , LKML , KOSAKI Motohiro , Matt Mackall , Alexey Dobriyan , "linux-mm@kvack.org" Subject: Re: [PATCH 5/5] proc: export more page flags in /proc/kpageflags Message-ID: <20090428092918.GC21085@elte.hu> References: <20090428010907.912554629@intel.com> <20090428014920.769723618@intel.com> <20090428065507.GA2024@elte.hu> <20090428074031.GK27382@one.firstfloor.org> <1240909484.1982.16.camel@penberg-laptop> <20090428091508.GA21085@elte.hu> <84144f020904280219p197d5ceag846ae9a80a76884e@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <84144f020904280219p197d5ceag846ae9a80a76884e@mail.gmail.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian 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: 1128 Lines: 29 * Pekka Enberg wrote: > I have no idea how expensive tracepoints are but I suspect they > don't make too much sense for this particular scenario. After all, > kmemtrace is mainly interested in _allocation patterns_ whereas > this patch seems to be more interested in "memory layout" type of > things. My point is that the allocation patterns can be derived from dynamic events. We can build a map of everything if we know all the events that led up to it. Doing: echo 3 > /proc/sys/vm/drop_caches will clear 99% of the memory allocations, so we can build a new map from scratch just about anytime. (and if boot allocations are interesting they can be traced too) _And_ via this angle we'll also have access to the dynamic events, in a different 'view' of the same tracepoints - which is obviously very useful for different purposes. 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/