From: Phillip Susi <psusi@cfl.rr.com>
To: David Chinner <dgc@sgi.com>
Cc: Neil Brown <neilb@suse.de>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
dm-devel@redhat.com, linux-raid@vger.kernel.org,
Jens Axboe <jens.axboe@oracle.com>,
Stefan Bader <Stefan.Bader@de.ibm.com>,
Andreas Dilger <adilger@clusterfs.com>,
Tejun Heo <htejun@gmail.com>
Subject: Re: [RFD] BIO_RW_BARRIER - what it means for devices, filesystems, and dm/md.
Date: Wed, 30 May 2007 12:45:09 -0400 [thread overview]
Message-ID: <465DAA15.3070703@cfl.rr.com> (raw)
In-Reply-To: <20070529234832.GT85884050@sgi.com>
David Chinner wrote:
>> Barrier != synchronous write,
>
> Of course. FYI, XFS only issues barriers on *async* writes.
>
> But barrier semantics - as far as they've been described by everyone
> but you indicate that the barrier write is guaranteed to be on stable
> storage when it returns.
Hrm... I may have misunderstood the perspective you were talking from.
Yes, when the bio is completed it must be on the media, but the
filesystem should issue both requests, and then really not care when
they complete. That is to say, the filesystem should not wait for block
A to finish before issuing block B; it should issue both, and use
barriers to make sure they hit the disk in the correct order.
> XFS relies on the block being stable before any other write
> goes to disk. That is the semantic that the barrier I/Os currently
> have. How that is implemented in the device is irrelevant to me,
> but if I issue a barrier I/O, I do not expect *any* I/O to be
> reordered around it.
Right... it just needs to control the order of the requests, just not
wait on one to finish before issuing the next.
next prev parent reply other threads:[~2007-05-30 16:45 UTC|newest]
Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-25 7:58 [RFD] BIO_RW_BARRIER - what it means for devices, filesystems, and dm/md Neil Brown
2007-05-25 11:15 ` David Chinner
2007-05-25 11:49 ` Jens Axboe
2007-05-25 14:49 ` Phillip Susi
2007-05-28 18:32 ` [dm-devel] " Jens Axboe
2007-05-25 13:52 ` Stefan Bader
2007-05-28 1:37 ` Neil Brown
2007-05-29 9:12 ` Stefan Bader
2007-05-25 15:11 ` Phillip Susi
2007-05-26 1:03 ` Andreas Dilger
2007-05-26 10:27 ` Tejun Heo
2007-05-28 1:30 ` Neil Brown
2007-05-28 2:45 ` David Chinner
2007-05-28 2:57 ` Neil Brown
2007-05-28 4:29 ` David Chinner
2007-05-31 0:46 ` Neil Brown
2007-05-31 0:57 ` Alasdair G Kergon
2007-05-31 1:07 ` Alasdair G Kergon
2007-05-31 1:11 ` David Chinner
2007-05-28 4:48 ` Timothy Shimmin
2007-05-29 6:45 ` Jeremy Higdon
2007-05-29 20:03 ` Phillip Susi
2007-05-29 23:48 ` David Chinner
2007-05-30 0:01 ` david
2007-05-30 6:17 ` David Chinner
2007-05-30 8:55 ` Stefan Bader
2007-05-30 16:52 ` david
2007-05-31 0:20 ` David Chinner
2007-05-31 6:26 ` Jens Axboe
2007-05-31 7:03 ` David Chinner
2007-05-31 7:06 ` Jens Axboe
2007-05-31 13:30 ` Bill Davidsen
2007-05-31 13:36 ` Jens Axboe
2007-06-01 16:04 ` Bill Davidsen
2007-06-02 14:51 ` Jens Axboe
2007-06-02 19:55 ` Bill Davidsen
2007-06-01 3:16 ` Tejun Heo
2007-06-01 8:21 ` Jens Axboe
2007-06-02 9:20 ` Tejun Heo
2007-06-02 14:34 ` Jens Axboe
2007-06-02 22:57 ` Guy Watkins
2007-06-04 7:39 ` Tejun Heo
2007-05-31 18:31 ` Phillip Susi
2007-05-31 19:00 ` Jens Axboe
2007-05-31 19:21 ` david
2007-05-31 19:40 ` Jens Axboe
2007-05-31 23:34 ` David Chinner
2007-06-01 5:59 ` Neil Brown
2007-06-01 6:11 ` Jens Axboe
2007-06-01 7:53 ` David Chinner
2007-06-01 23:56 ` Bill Davidsen
2007-05-31 18:24 ` Phillip Susi
2007-05-30 16:45 ` Phillip Susi [this message]
2007-05-30 20:27 ` [dm-devel] " Phillip Susi
2007-05-31 6:24 ` Jens Axboe
2007-05-31 18:37 ` [dm-devel] " Phillip Susi
2007-05-31 18:58 ` Jens Axboe
2007-06-02 0:04 ` Bill Davidsen
2007-05-28 9:29 ` Tejun Heo
2007-05-28 9:43 ` Alasdair G Kergon
2007-05-29 9:25 ` [dm-devel] " Stefan Bader
2007-05-29 22:05 ` Alasdair G Kergon
2007-05-30 9:12 ` [dm-devel] " Stefan Bader
2007-05-30 10:41 ` Alasdair G Kergon
2007-05-30 16:55 ` Phillip Susi
2007-05-31 11:14 ` [dm-devel] " Stefan Bader
2007-06-01 3:25 ` Tejun Heo
2007-06-01 5:55 ` david
2007-06-01 7:16 ` [dm-devel] " Tejun Heo
2007-06-01 17:07 ` Valdis.Kletnieks
2007-06-01 18:09 ` Tejun Heo
2007-07-10 18:39 ` Ric Wheeler
2007-07-10 23:40 ` Valdis.Kletnieks
2007-07-11 2:49 ` Tejun Heo
2007-07-11 22:44 ` Ric Wheeler
2007-07-12 17:34 ` Valdis.Kletnieks
2007-07-12 19:43 ` Ric Wheeler
2007-07-12 23:10 ` Guy Watkins
2007-07-13 11:30 ` Ric Wheeler
2007-07-11 2:51 ` Tejun Heo
2007-05-29 19:59 ` Phillip Susi
2007-05-31 0:22 ` Neil Brown
2007-05-30 9:35 ` Jens Axboe
2007-07-05 12:28 ` Tejun Heo
2007-07-09 12:27 ` Jens Axboe
2007-07-18 10:56 ` [PATCH] block: cosmetic changes Tejun Heo
2007-07-18 10:59 ` [PATCH] block: factor out bio_check_eod() Tejun Heo
2007-07-18 11:06 ` Jens Axboe
2007-07-18 11:18 ` Tejun Heo
2007-07-18 11:31 ` Jens Axboe
2007-07-18 11:33 ` Tejun Heo
2007-07-18 11:34 ` Jens Axboe
2007-07-18 11:41 ` Tejun Heo
2007-07-18 11:45 ` Jens Axboe
2007-07-18 11:49 ` Jens Axboe
2007-07-18 12:34 ` Tejun Heo
2007-07-18 12:31 ` Jens Axboe
2007-05-28 11:17 ` [RFD] BIO_RW_BARRIER - what it means for devices, filesystems, and dm/md Nikita Danilov
2007-05-31 3:31 ` Neil Brown
2007-05-28 14:43 ` Bill Davidsen
2007-05-31 0:37 ` Neil Brown
2007-05-31 12:28 ` Bill Davidsen
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