From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753717Ab2A3CWe (ORCPT ); Sun, 29 Jan 2012 21:22:34 -0500 Received: from LGEMRELSE6Q.lge.com ([156.147.1.121]:52771 "EHLO LGEMRELSE6Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752368Ab2A3CWd (ORCPT ); Sun, 29 Jan 2012 21:22:33 -0500 X-AuditID: 9c930179-b7bf0ae00000132b-53-4f25fee7b607 Message-ID: <4F25FEE5.5010309@gmail.com> Date: Mon, 30 Jan 2012 11:22:29 +0900 From: Namhyung Kim User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:9.0) Gecko/20111222 Thunderbird/9.0.1 MIME-Version: 1.0 Newsgroups: gmane.linux.kernel,gmane.linux.kernel.device-mapper.devel To: Tejun Heo CC: Jens Axboe , linux-kernel@vger.kernel.org, Steven Rostedt , dm-devel@redhat.com Subject: Re: [PATCH] block: add missing block_bio_complete() tracepoint References: <1327830093-12130-1-git-send-email-namhyung@gmail.com> <20120129192447.GB17211@htj.dyndns.org> <4F25F5F3.6060507@gmail.com> <20120130014703.GG17211@htj.dyndns.org> In-Reply-To: <20120130014703.GG17211@htj.dyndns.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2012-01-30 10:47 AM, Tejun Heo wrote: > On Mon, Jan 30, 2012 at 10:44:19 AM +0900, Namhyung Kim wrote: >> The userland tool cannot distinguish bounced bio from original one >> at completion TP, but it can expect there will be a duplicated >> BLK_TA_COMPLETE as it sees BLK_TA_BOUNCE for the bio before. >> >> Filtering it out from kernel side seems to hide a real information >> that (paranoid?) user might want to get, and it looks like providing >> "polcy not mechanism" IMHO. That's why I changed my mind finally. >> >> I cannot think of the downside, anyway it's not a big deal, if you >> think it's wrong choice, I'm OK to change it again. > > It's just that this patch as it stands will break the existing tools > and is likely to cause some amount of head scratching for blktrace > users upgrading to new kernel with existing userland, so yeah, I think > it should be filtered in kernel from blktrace.c. > > Thanks. > Will it break blktrace? Looking at the code, not tested though, it will just add one more 'C' line for bounced bio, and that's it? The blktrace will get way more 'C' lines for normal request based devices and it needs to be handled anyway. Am I missing something? Thanks, Namhyung