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

From: Jens Axboe
Date: Fri May 27 2011 - 16:17:19 EST


On 2011-05-27 17:13, Namhyung Kim wrote:
> 2011-05-27 (ê), 09:57 -0400, Mike Snitzer:
>> On Fri, May 27, 2011 at 9:12 AM, Christoph Hellwig <hch@xxxxxxxxxxxxx> 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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