From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754924AbZEIJo3 (ORCPT ); Sat, 9 May 2009 05:44:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751139AbZEIJoU (ORCPT ); Sat, 9 May 2009 05:44:20 -0400 Received: from mga03.intel.com ([143.182.124.21]:57353 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751137AbZEIJoT (ORCPT ); Sat, 9 May 2009 05:44:19 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.40,320,1239001200"; d="scan'208";a="140992228" Date: Sat, 9 May 2009 17:43:16 +0800 From: Wu Fengguang To: Ingo Molnar Cc: =?utf-8?B?RnLDqWTDqXJpYw==?= Weisbecker , Steven Rostedt , Peter Zijlstra , Li Zefan , Andrew Morton , LKML , KOSAKI Motohiro , Andi Kleen , Matt Mackall , Alexey Dobriyan , "linux-mm@kvack.org" Subject: Re: [patch] tracing/mm: add page frame snapshot trace Message-ID: <20090509094316.GA5520@localhost> References: <20090508105320.316173813@intel.com> <20090508111031.020574236@intel.com> <20090508114742.GB17129@elte.hu> <20090508124433.GB15949@localhost> <20090509062758.GB21354@elte.hu> <20090509091325.GA7994@localhost> <20090509092431.GB13784@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090509092431.GB13784@elte.hu> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, May 09, 2009 at 05:24:31PM +0800, Ingo Molnar wrote: > > * Wu Fengguang wrote: > > > Hi Ingo, > > > > On Sat, May 09, 2009 at 02:27:58PM +0800, Ingo Molnar wrote: > > > > > > * Wu Fengguang wrote: > > > > > > > > So this should be done in cooperation with instrumentation > > > > > folks, while improving _all_ of Linux instrumentation in > > > > > general. Or, if you dont have the time/interest to work with us > > > > > on that, it should not be done at all. Not having the > > > > > resources/interest to do something properly is not a license to > > > > > introduce further instrumentation crap into Linux. > > > > > > > > I'd be glad to work with you on the 'object collections' ftrace > > > > interfaces. Maybe next month. For now my time have been allocated > > > > for the hwpoison work, sorry! > > > > > > No problem - our offer still stands: we are glad to help out with > > > the instrumentation side bits. We'll even write all the patches for > > > you, just please help us out with making it maximally useful to > > > _you_ :-) > > > > Thank you very much! > > > > The good fact is, 2/3 of the code and experiences can be reused. > > > > > Find below a first prototype patch written by Steve yesterday and > > > tidied up a bit by me today. It can also be tried on latest -tip: > > > > > > http://people.redhat.com/mingo/tip.git/README > > > > > > This patch adds the first version of the 'object collections' > > > instrumentation facility under /debug/tracing/objects/mm/. It has a > > > single control so far, a 'number of pages to dump' trigger file: > > > > > > To dump 1000 pages to the trace buffers, do: > > > > > > echo 1000 > /debug/tracing/objects/mm/pages/trigger > > > > > > To dump all pages to the trace buffers, do: > > > > > > echo -1 > /debug/tracing/objects/mm/pages/trigger > > > > That is not too intuitive, I'm afraid. > > This was just a first-level approximation - and it matches the usual > "0xffffffff means infinite" idiom. 8^) > How about changing it from 'trigger' to 'dump_range': That's a better name! > echo "*" > /debug/tracing/objects/mm/pages/dump_range > > being a shortcut for 'dump all'? No I'm not complaining about -1. That's even better than "*", because the latter can easily be expanded by shell ;) > And: > > echo "1000 2000" > /debug/tracing/objects/mm/pages/dump_range > > ? Now it's much more intuitive! > The '1000' is the offset where the dumping starts, and 2000 is the > size of the dump. Ah the second parameter 2000 can easily be taken as "end"..