From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id 99E576B0047 for ; Tue, 28 Apr 2009 05:04:43 -0400 (EDT) Subject: Re: [PATCH 5/5] proc: export more page flags in /proc/kpageflags From: Pekka Enberg In-Reply-To: <20090428074031.GK27382@one.firstfloor.org> References: <20090428010907.912554629@intel.com> <20090428014920.769723618@intel.com> <20090428065507.GA2024@elte.hu> <20090428074031.GK27382@one.firstfloor.org> Date: Tue, 28 Apr 2009 12:04:44 +0300 Message-Id: <1240909484.1982.16.camel@penberg-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Andi Kleen Cc: Ingo Molnar , 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 Andi, 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 > > I think because it has zero fast path overhead and can be used > any time without enabling anything special. Yes, zero overhead is important for certain things (like CONFIG_SLUB_STATS, for example). However, putting slab allocator specific checks in fs/proc looks pretty fragile to me. It would be nice to have this under the "kmemtrace umbrella" so that there's just one place that needs to be fixed up when allocators change. Also, while you probably don't want to use tracepoints for this kind of instrumentation, you might want to look into reusing the ftrace reporting bits. 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