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Date: Wed, 10 Jun 2009 09:01:27 -0400
From: Theodore Tso <tytso@mit.edu>
To: =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
       linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
       Minchan Kim <minchan.kim@gmail.com>, Mel Gorman <mel@csn.ul.ie>,
       Christoph Hellwig <hch@infradead.org>, Rik van Riel <riel@redhat.com>,
       Pekka Enberg <penberg@cs.helsinki.fi>,
       Peter Zijlstra <peterz@infradead.org>,
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       KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
       Jason Baron <jbaron@redhat.com>, Jiaying Zhang <jiayingz@google.com>,
       Tom Zanussi <tzanussi@gmail.com>,
       Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Subject: Re: [PATCH 00/11] [GIT PULL] more updates for the tag format
Message-ID: <20090610130127.GA6647@mit.edu>
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On Wed, Jun 10, 2009 at 01:11:40PM +0200, Fr?d?ric Weisbecker wrote:
> Well, indeed I had worries, but I discussed about it with Steven and
> now I actually
> think this new tag format is much more powerful than printf style.
> It brings a cleaner, and much higher level way to control the data exports.
> 
> But it would be nice to read some opinions from end users (end
> developers) of TRACE_EVENT().

Maybe I'm missing something, but looks like the this new format, while
simpler and easier to read, doesn't have support for using a more
complicated C expression as a printk argument.  For example:

	TP_printk("dev %s ino %lu mode %d uid %u gid %u blocks %llu",
		  jbd2_dev_to_name(__entry->dev), __entry->ino, __entry->mode,
		  __entry->uid, __entry->gid, __entry->blocks)

How should I handle the "jbd2_dev_to_name(__entry->dev)" argument to
TP_printk?  The whole point of calling jbd2_dev_to_name() at TP_printk
time is to not bloat the ring buffer with a 32 byte devname.

     	       	     	      	     	  - Ted
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