From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
To: Phillip Susi <psusi@cfl.rr.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
"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 17:25:44 +0100 [thread overview]
Message-ID: <58cb370e0601180825l105d81fbk9a5e57b722255f96@mail.gmail.com> (raw)
In-Reply-To: <43CE6363.2020402@cfl.rr.com>
On 1/18/06, Phillip Susi <psusi@cfl.rr.com> wrote:
> 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?
Yes if:
* you have a disk supporting FUA
* you have kernel >= 2.6.16-rc1
* you are using SCSI (this includes libata) driver [ support for IDE driver
will be merged later when races in changing IDE settings are fixed ]
Bartlomiej
> 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.
next prev parent reply other threads:[~2006-01-18 16:25 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
2006-01-18 16:25 ` Bartlomiej Zolnierkiewicz [this message]
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
2006-01-19 11:39 Al Boldi
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