From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754309AbZIHKuf (ORCPT ); Tue, 8 Sep 2009 06:50:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753778AbZIHKue (ORCPT ); Tue, 8 Sep 2009 06:50:34 -0400 Received: from brick.kernel.dk ([93.163.65.50]:37896 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753695AbZIHKue (ORCPT ); Tue, 8 Sep 2009 06:50:34 -0400 Date: Tue, 8 Sep 2009 12:50:36 +0200 From: Jens Axboe To: Wu Fengguang Cc: Minchan Kim , Andrew Morton , lkml , "lizf@cn.fujitsu.com" Subject: Re: [PATCH] trace bio queueing trial only when it occurs Message-ID: <20090908105036.GT18599@kernel.dk> References: <20090908093416.5a2f98b6.minchan.kim@barrios-desktop> <20090908005520.GA7967@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090908005520.GA7967@localhost> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 08 2009, Wu Fengguang wrote: > Minchan, > > I tend to agree with the change, but somehow confused by blkparse(1): > > Q -- queued This notes *intent* to queue i/o at the given location. No real requests exists yet. > > Li Zefan has been working on blktrace and he can tell more. The documentation details the original implementation. I'm guessing the need to move this trace hook is due to some user space tracking that gets confused, because it cannot match the queue intent with a merge or an insert. I have no problems moving the trace call. If we had a matching bio_endio trace, then I'd say moving it would lose information. But right now it doesn't. -- Jens Axboe