Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753569AbZDNI1H (ORCPT ); Tue, 14 Apr 2009 04:27:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752152AbZDNI0v (ORCPT ); Tue, 14 Apr 2009 04:26:51 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:51002 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752011AbZDNI0u (ORCPT ); Tue, 14 Apr 2009 04:26:50 -0400 Message-ID: <49E448F6.5010506@cn.fujitsu.com> Date: Tue, 14 Apr 2009 16:27:34 +0800 From: Li Zefan User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Ingo Molnar 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 References: <49E42620.4050701@cn.fujitsu.com> <20090414080919.GB27003@elte.hu> In-Reply-To: <20090414080919.GB27003@elte.hu> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2566 Lines: 72 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 > 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' But yes the pid filter is not exposed in user-space blktrace. > But before we can lift all these limitations and can have equivalent > functionality in the generic event tracer we still need more filter > engine infrastructure work (range operators and dev_t field > support). Plus TRACE_EVENT() based blk tracepoints. > > Once we have that, the conversion will be straightforward: all > existing filter functionality of blktrace is static, so it will map > directly to new-style filter expressions. That will give us block > tracing for an arbitrary number of block devices (including the > basic mode of 'trace all block IO in the system') and a much wider > range of filtering capabilities. > > Thanks, > > 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/