Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752204AbZDNIjg (ORCPT ); Tue, 14 Apr 2009 04:39:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750856AbZDNIj0 (ORCPT ); Tue, 14 Apr 2009 04:39:26 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:51884 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750746AbZDNIjZ (ORCPT ); Tue, 14 Apr 2009 04:39:25 -0400 Date: Tue, 14 Apr 2009 10:38:56 +0200 From: Ingo Molnar To: Li Zefan Cc: Steven Rostedt , Tom Zanussi , Jens Axboe , Arnaldo Carvalho de Melo , "Theodore Ts'o" , Shawn Du , LKML , linux-btrace@vger.kernel.org Subject: Re: PATCH 1/3] blktrace: support per-partition tracing Message-ID: <20090414083856.GF27003@elte.hu> References: <49E42620.4050701@cn.fujitsu.com> <20090414080919.GB27003@elte.hu> <49E448F6.5010506@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <49E448F6.5010506@cn.fujitsu.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.3 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.3 required=5.9 tests=BAYES_00,SUBJECT_FUZZY_TION autolearn=no SpamAssassin version=3.2.3 0.2 SUBJECT_FUZZY_TION Attempt to obfuscate words in Subject: -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2430 Lines: 70 * Li Zefan wrote: > Ingo Molnar wrote: > > * Li Zefan wrote: > > > >> From: Shawn Du > >> > >> Though one can specify '-d /dev/sda1' when using blktrace, it > >> still traces the whole sda. > >> > >> To support per-partition tracing, when we start tracing, we > >> initialize bt->start_lba and bt->end_lba to the start and end > >> sector of that partition. > >> > >> Note some actions are per device, thus we don't filter 0-sector > >> events. > >> > >> The original patch and discussion can be found here: > >> http://marc.info/?l=linux-btrace&m=122949374214540&w=2 > >> > >> Signed-off-by: Shawn Du > >> Signed-off-by: Li Zefan > > > > Thanks - beyond the small detail i mailed about a few minutes ago > > the series looks good: i'll queue this up in tracing/blktrace unless > > Jens has second thoughts. > > > > Lets note that this approach still has the (long existing) > > limitation that only one device can be block-traced at a time. > > > > No, both userspace blktrace and ftrace-plugin trace can trace > more than one device at a time. > > # btrace /dev/sda /dev/dm-0 > > or > > # echo 1 > /sys/block/sda/trace/enable > # echo 1 > /sys/block/dm-0/trace/enable When they are independent - but not multiple partitions at a time: [root@aldebaran ~]# echo 1 > /sys/block/sda/sda1/trace/enable [root@aldebaran ~]# echo 1 > /sys/block/sda/sda2/trace/enable -bash: echo: write error: Device or resource busy [root@aldebaran ~]# Nor did i see any "trace all block IO in the system" kind of functionality in blktrace. (or maybe there's one that i missed?) > > Furthermore, various other aspects of act_log_check() itself > > could be expressed in terms of per tracepoint filters as well: > > the PID filter field for example - which is supported in the > > ioctl ABI but currently not exposed in the user-space blktrace > > utility. Same goes for the action mask which is frequently used. > > > > Actually action mask can be specified by 'blktrace -a/-A > mask/mask_name' Yes, this is what i meant by "which is frequently used". Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/