From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933733Ab2AKSI2 (ORCPT ); Wed, 11 Jan 2012 13:08:28 -0500 Received: from mail-iy0-f174.google.com ([209.85.210.174]:56027 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933586Ab2AKSIX (ORCPT ); Wed, 11 Jan 2012 13:08:23 -0500 Date: Wed, 11 Jan 2012 10:08:17 -0800 From: Tejun Heo To: axboe@kernel.dk, mingo@redhat.com, rostedt@goodmis.org, fweisbec@gmail.com, teravest@google.com, slavapestov@google.com, ctalbott@google.com, dhsharp@google.com Cc: linux-kernel@vger.kernel.org, winget@google.com, namhyung@gmail.com, Chanho Park Subject: Re: [PATCH RESEND 9/9] block, trace: implement ioblame - IO tracer with origin tracking Message-ID: <20120111180817.GJ26832@google.com> References: <1326220106-5765-1-git-send-email-tj@kernel.org> <1326220106-5765-10-git-send-email-tj@kernel.org> <20120111013212.GA6843@dhcp-172-17-108-109.mtv.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120111013212.GA6843@dhcp-172-17-108-109.mtv.corp.google.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 10, 2012 at 05:32:12PM -0800, Tejun Heo wrote: > Implement ioblame, which can attribute each IO to its origin and > export the information using a tracepoint. > > Operations which may eventually cause IOs and IO operations themselves > are identified and tracked primarily by their stack traces along with > the task and the target file (dev:ino:gen). On each IO completion, > ioblame knows why that specific IO happened and exports the > information via ioblame:ioblame_io tracepoint. > > While ioblame adds fields to a few fs and block layer objects, all > logic is well insulated inside ioblame proper and all hooking goes > through well defined tracepoints and doesn't add any significant > maintenance overhead. > > For details, please read Documentation/trace/ioblame.txt. > > -v2: Namhyung pointed out that all the information available at IO > completion can be exported via tracepoint and letting userland do > whatever it wants to do with that would be better. Stripped out > in-kernel statistics gathering. > > Now that everything is exported through tracepoint, iolog and > counters_pipe[_pipe] are unnecessary. Removed. intents_bin too > is removed. > > As data collection no longer requires polling, ioblame/intents is > updated to generate inotify IN_MODIFY event after a new intent is > created. One planned update is exporting issuer and dirtier separately. Currently dirtier, if exists, simply overrides issuer as it wasn't useful for in-kernel statistics anyway. With that gone, I think it makes much more sense to expose both of them. Thanks. -- tejun