Date: Mon, 15 Jan 2007 18:36:40 -0600
From: Robert Hancock <hancockr@shaw.ca>
Subject: Re: SATA exceptions with 2.6.20-rc5
In-reply-to: <20070116002336.GB4067@kernel.dk>
To: Jens Axboe <jens.axboe@oracle.com>
Cc: Jeff Garzik <jeff@garzik.org>,
       =?ISO-8859-1?Q?Bj=F6rn_Steinbrink?= <B.Steinbrink@gmx.de>,
       linux-kernel@vger.kernel.org, htejun@gmail.com
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Jens Axboe wrote:
> On Mon, Jan 15 2007, Jeff Garzik wrote:
>> Jens Axboe wrote:
>>> I'd be surprised if the device would not obey the 7 second timeout rule
>>> that seems to be set in stone and not allow more dirty in-drive cache
>>> than it could flush out in approximately that time.
>> AFAIK Windows flush-cache timeout is 30 seconds, not 7 as with other 
>> commands...
> 
> Ok, 7 seconds for FLUSH_CACHE would have been nice for us too though, as
> it would pretty much guarentee lower latencies for random writes and
> write back caching. The concern is the barrier code, of course. I guess
> I should do some timings on potential worst case patterns some day. Alan
> may have done that sometime in the past, iirc.
> 

Note that the ATA-7 spec for FLUSH CACHE says that "This command may 
take longer than 30 s to complete."

-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/

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