From: Phillip Susi <psusi@cfl.rr.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: "Jeff V. Merkey" <jmerkey@wolfmountaingroup.com>,
Max Waterman <davidmaxwaterman@fastmail.co.uk>,
linux-kernel@vger.kernel.org
Subject: Re: io performance...
Date: Wed, 18 Jan 2006 10:48:51 -0500 [thread overview]
Message-ID: <43CE6363.2020402@cfl.rr.com> (raw)
In-Reply-To: <1137576064.25819.11.camel@localhost.localdomain>
I was going to say, doesn't the kernel set the FUA bit on the write
request to push important flushes through the disk's write-back cache?
Like for filesystem journal flushes?
Alan Cox wrote:
> Not always. If you have a cache flush command and the OS knows about
> using it, or if you don't care if the data gets lost over a power
> failure (eg /tmp and swap) it makes sense to force it.
>
> The raid controller drivers that fake scsi don't always fake enough of
> scsi to report that they support cache flushes and the like. That
> doesn't mean the controller itself is neccessarily doing one thing or
> the other.
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
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> Please read the FAQ at http://www.tux.org/lkml/
>
>
>
next prev parent reply other threads:[~2006-01-18 15:49 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-16 7:35 io performance Max Waterman
2006-01-16 7:32 ` Jeff V. Merkey
2006-01-17 13:57 ` Jens Axboe
2006-01-17 19:17 ` Jeff V. Merkey
2006-01-16 8:35 ` Pekka Enberg
2006-01-17 17:06 ` Phillip Susi
2006-01-18 7:24 ` Max Waterman
2006-01-18 15:19 ` Phillip Susi
2006-01-20 5:58 ` Max Waterman
2006-01-20 13:42 ` Ian Soboroff
2006-01-25 6:36 ` Max Waterman
2006-01-25 14:19 ` Ian Soboroff
2006-01-25 13:09 ` Bernd Eckenfels
2006-01-18 3:02 ` Max Waterman
2006-01-18 4:30 ` Jeff V. Merkey
2006-01-18 5:09 ` Max Waterman
2006-01-18 4:37 ` Jeff V. Merkey
2006-01-18 7:06 ` Max Waterman
2006-01-18 9:21 ` Alan Cox
2006-01-18 15:48 ` Phillip Susi [this message]
2006-01-18 16:25 ` Bartlomiej Zolnierkiewicz
2006-01-19 0:48 ` Adrian Bunk
2006-01-19 13:18 ` Max Waterman
[not found] <5vx8f-1Al-21@gated-at.bofh.it>
[not found] ` <5wbRY-3cF-3@gated-at.bofh.it>
[not found] ` <5wdKh-5wF-15@gated-at.bofh.it>
2006-01-19 1:58 ` Robert Hancock
2006-01-19 13:14 ` Max Waterman
2006-01-19 14:08 ` Alan Cox
2006-01-20 4:09 ` Max Waterman
2006-01-20 4:27 ` Alexander Samad
2006-01-20 12:52 ` Alan Cox
-- strict thread matches above, loose matches on Subject: below --
2006-01-19 11:39 Al Boldi
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