From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 27EB36B003D for ; Tue, 28 Apr 2009 05:19:34 -0400 (EDT) Received: by bwz21 with SMTP id 21so510299bwz.38 for ; Tue, 28 Apr 2009 02:19:50 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20090428091508.GA21085@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> Date: Tue, 28 Apr 2009 12:19:50 +0300 Message-ID: <84144f020904280219p197d5ceag846ae9a80a76884e@mail.gmail.com> Subject: Re: [PATCH 5/5] proc: export more page flags in /proc/kpageflags From: Pekka Enberg Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org To: Ingo Molnar 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" List-ID: Hi Ingo, On Tue, 2009-04-28 at 09:40 +0200, Andi Kleen wrote: >> > > I think i have to NAK this kind of ad-hoc instrumentation of kernel >> > > internals and statistics until we clear up why such instrumentation * Pekka Enberg wrote: >> > I think because it has zero fast path overhead and can be used >> > any time without enabling anything special. On Tue, Apr 28, 2009 at 12:15 PM, Ingo Molnar wrote: > ( That's a dubious claim in any case - tracepoints are very cheap. > =A0And they could be made even cheaper and such efforts would benefit > =A0all the tracepoint users so it's a prime focus of interest. > =A0Andi is a SystemTap proponent, right? I saw him oppose pretty much > =A0everything built-in kernel tracing related. I consider that a > =A0pretty extreme position. ) 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. Pekka -- 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