linux-kernel - Re: [PATCH 1/2] blktrace: treat flush as barrier

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Message-ID: <4DE006C5.4010906@fusionio.com>
Date:	Fri, 27 May 2011 22:17:09 +0200
From:	Jens Axboe <jaxboe@...ionio.com>
To:	Namhyung Kim <namhyung@...il.com>
CC:	Mike Snitzer <snitzer@...hat.com>,
	Christoph Hellwig <hch@...radead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH 1/2] blktrace: treat flush as barrier

On 2011-05-27 17:13, Namhyung Kim wrote:
> 2011-05-27 (금), 09:57 -0400, Mike Snitzer:
>> On Fri, May 27, 2011 at 9:12 AM, Christoph Hellwig <hch@...radead.org> wrote:
>>> On Fri, May 27, 2011 at 10:11:22PM +0900, Namhyung Kim wrote:
>>>> Since BARRIER requests have been converted to FLUSH/FUA, it would be
>>>> better for blktrace to recognize FLUSH requests as BARRIER for the
>>>> backward-compatibility IMHO.
>>>
>>> I'd rather see new flags for them.  F and U maybe?
>>
>> Somehow I'm not surprised by your F and U suggestion -- appropriate on
>> multiple levels :)
> 
> OK. I'll work on that direction.
> Thanks.

Agree on Christophs comments, we should not pretend they are the same
(since they are not). Since flush is a request on its own, F works
nicely. For FUA it's associated with a write, so F should work there too
indicating Write Fua (and easily humanly parsed as that, or Write
Flush). WU would look confusing.

-- 
Jens Axboe

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