From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755254Ab2AIBt5 (ORCPT ); Sun, 8 Jan 2012 20:49:57 -0500 Received: from mail-tul01m020-f174.google.com ([209.85.214.174]:60476 "EHLO mail-tul01m020-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755093Ab2AIBtz (ORCPT ); Sun, 8 Jan 2012 20:49:55 -0500 Date: Sun, 8 Jan 2012 17:49:49 -0800 From: Tejun Heo To: Namhyung Kim Cc: axboe@kernel.dk, mingo@redhat.com, rostedt@goodmis.org, fweisbec@gmail.com, teravest@google.com, slavapestov@google.com, ctalbott@google.com, dsharp@google.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 03/11] block: block_bio_complete tracepoint was missing Message-ID: <20120109014949.GA16360@mtj.dyndns.org> References: <1325806974-23486-1-git-send-email-tj@kernel.org> <1325806974-23486-4-git-send-email-tj@kernel.org> <4F0A431E.3090106@lge.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4F0A431E.3090106@lge.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Mon, Jan 09, 2012 at 10:30:06AM +0900, Namhyung Kim wrote: > Just adding the TP unconditionally will produce duplicated (in some > sense) reports about the completion. For example, normal request > based IO reports whole request completion prior to its bio's, and > further Request and bio completions are separate events. There's nothing wrong with reporting them separately. In fact, I think they should be reported separately. >, some of nested block IO handling routines - bounced bio and > btrfs with compression, etc - call bio_endio() more than once. Also > there are cases that bio fails before it's enqueued for some reason. They are actually separate bio's being completed. I don't think trying to put extra semantics on TP itself is a good idea. In general, TP signals that such event happened with sufficient information and it's the consumers' responsibility to make sense of what's going on. BIO_CLONED/BOUNCED are there. > I have no idea about the ioblame can deal with all of such corner > cases. However it might confuse blktrace somewhat, I guess. Unless someone is doing memcpy() on bio's, ioblame should be okay. It only considers bio's which went through actual submission. > I already posted similar patch a couple of weeks ago, but didn't > receive a comment yet. [1] Please take a look this too :) I'll reply there but don't think imposing such extra logic on TP is a good idea. > After a quick glance, the ioblame seems to carry all IO accounting > info through the first bio in the request. If so, why don't you use > the request structure for that? Because there are bio based drivers which don't use requests at all. Thanks. -- tejun