From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756750AbZCYHHh (ORCPT ); Wed, 25 Mar 2009 03:07:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756115AbZCYHH3 (ORCPT ); Wed, 25 Mar 2009 03:07:29 -0400 Received: from brick.kernel.dk ([93.163.65.50]:52441 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754626AbZCYHH3 (ORCPT ); Wed, 25 Mar 2009 03:07:29 -0400 Date: Wed, 25 Mar 2009 08:07:26 +0100 From: Jens Axboe To: Li Zefan Cc: Ingo Molnar , Arnaldo Carvalho de Melo , Frederic Weisbecker , Steven Rostedt , LKML Subject: Re: [RFC][PATCH] blktrace: fix original blktrace Message-ID: <20090325070726.GD27476@kernel.dk> References: <49C99BD2.9090503@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <49C99BD2.9090503@cn.fujitsu.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 25 2009, Li Zefan wrote: > I'm wondering what we are going to do with the original blktrace which > is using relay and is used via ioctl. > > The problem is currently it's totally broken. You can use ftrace to see > the output of blktrace, but user-space blktrace is unusable. > > With this patch, both ioctl and ftrace can be used, but of course you > can't use both of them at the same time. Even if ftrace was as fast as storing huge amounts of data as blktrace, it's still of utmost importance that nothing is broken there. There are people actually USING this tracing to do real work, it's not a playground. I appreciate the efforts to unify and improve our tracing, but we must not be breaking blktrace along the way. Otherwise the whole thing goes back to block/blktrace.c, period. -- Jens Axboe