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Date: Wed, 25 Mar 2009 16:25:08 -0400
From: Ric Wheeler <rwheeler@redhat.com>
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To: Jeff Garzik <jeff@garzik.org>,
       James Bottomley <James.Bottomley@HansenPartnership.com>
CC: Ric Wheeler <rwheeler@redhat.com>, Jens Axboe <jens.axboe@oracle.com>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Theodore Tso <tytso@mit.edu>, Ingo Molnar <mingo@elte.hu>,
       Alan Cox <alan@lxorguk.ukuu.org.uk>,
       Arjan van de Ven <arjan@infradead.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>, Nick Piggin <npiggin@suse.de>,
       David Rees <drees76@gmail.com>, Jesper Krogh <jesper@krogh.cc>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Linux 2.6.29
References: <20090324093245.GA22483@elte.hu> <20090324101011.6555a0b9@lxorguk.ukuu.org.uk> <20090324103111.GA26691@elte.hu> <20090324132032.GK5814@mit.edu> <alpine.LFD.2.00.0903241053200.3032@localhost.localdomain> <20090324184549.GE32307@mit.edu> <alpine.LFD.2.00.0903241218130.3032@localhost.localdomain> <49C93AB0.6070300@garzik.org> <20090325093913.GJ27476@kernel.dk> <49CA86BD.6060205@garzik.org> <20090325194341.GB27476@kernel.dk> <49CA8ADA.3040709@redhat.com> <49CA9114.3040205@garzik.org>
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Jeff Garzik wrote:
> Ric Wheeler wrote:> And, as I am sure that you do know, to add insult 
> to injury, FLUSH_CACHE
>> is per device (not file system).
>>
>> When you issue an fsync() on a disk with multiple partitions, you 
>> will flush the data for all of its partitions from the write cache....
>
> SCSI'S SYNCHRONIZE CACHE command already accepts an (LBA, length) 
> pair.  We could make use of that.
>
> And I bet we could convince T13 to add FLUSH CACHE RANGE, if we could 
> demonstrate clear benefit.
>
>     Jeff

How well supported is this in SCSI?  Can we try it out with a commodity 
SAS drive?

Ric