From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752624AbZDMSBM (ORCPT ); Mon, 13 Apr 2009 14:01:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752085AbZDMSA4 (ORCPT ); Mon, 13 Apr 2009 14:00:56 -0400 Received: from brick.kernel.dk ([93.163.65.50]:50282 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751649AbZDMSAz (ORCPT ); Mon, 13 Apr 2009 14:00:55 -0400 Date: Mon, 13 Apr 2009 20:00:54 +0200 From: Jens Axboe To: Li Zefan Cc: Ingo Molnar , "Theodore Ts'o" , Arnaldo Carvalho de Melo , LKML Subject: Re: [PATCH] blktrace: move trace/ dir to /sys/block/sda/ Message-ID: <20090413180054.GZ5178@kernel.dk> References: <49E31931.5000506@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <49E31931.5000506@cn.fujitsu.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 13 2009, Li Zefan wrote: > Impact: allow ftrace-plugin blktrace to trace device-mapper devices > > blktrace can't trace a single partition, so it makes no sense to > have one trace/ dir in each /sys/block/sda/sdaX. Move it to > /sys/block/sda/. > > Thus we fix an issue reported by Ted, that ftrace-plugin blktrace > can't be used to trace device-mapper devices. Perhaps I never committed that patch, but it would be trivial to do partition based blktrace tracing. It's also quite useful. So please don't go changing things to make that harder to support, it would be nicer to just add the (small) bits to support per-partition tracing. It's basically just a start/stop sector range, while some events are per-device and should just be included always. -- Jens Axboe