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Date: Tue, 14 Apr 2009 17:32:07 -0400
From: Theodore Tso <tytso@mit.edu>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>, Jens Axboe <jens.axboe@oracle.com>,
       LKML <linux-kernel@vger.kernel.org>,
       Steven Rostedt <rostedt@goodmis.org>,
       Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: Re: blktrace: event traces displayed wrong while ftrace blktrace
	is active
Message-ID: <20090414213207.GP955@mit.edu>
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	LKML <linux-kernel@vger.kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Arnaldo Carvalho de Melo <acme@redhat.com>
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On Tue, Apr 14, 2009 at 11:25:33PM +0200, Frederic Weisbecker wrote:
> 
> Indeed. Note that you can overwrite this default by typing:
> 
> echo context-info > trace_option
> 
> after setting bkltrace as the current tracer.

The problem with doing that is that blktrace will then display this:

    fsync-tester-27934 [001]   208.031278:     fsync-tester-27934 [001]   208.031278: 254,4    Q  WS 268392 + 8 [fsync-tester]

I think the real problem is that blk trace is displaying the standard
context-info, so it's suppressing the normal context info.  So I have
the choice on having no context information on my event trace lines,
or two copies of the context information for the block trace lines.  

:-(

I'm guessing things were done this way in order to support the old
legancy blktrace format?

						- Ted
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