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Message-id: <45AC1E18.8030403@shaw.ca>
Date: Mon, 15 Jan 2007 18:36:40 -0600
From: Robert Hancock <hancockr@...w.ca>
To: Jens Axboe <jens.axboe@...cle.com>
Cc: Jeff Garzik <jeff@...zik.org>,
Björn Steinbrink <B.Steinbrink@....de>,
linux-kernel@...r.kernel.org, htejun@...il.com
Subject: Re: SATA exceptions with 2.6.20-rc5
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@...pamshaw.ca
Home Page: http://www.roberthancock.com/
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