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From: Matthew Wilcox <matthew@wil.cx>
To: Jeff Garzik <jeff@garzik.org>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Jens Axboe <jens.axboe@oracle.com>,
	rwheeler@redhat.com, snitzer@redhat.com, neilb@suse.de,
	dgilbert@interlog.com, linux-ide@vger.kernel.org,
	linux-scsi@vger.kernel.org
Subject: Re: [PATCH 5 of 8] sd: Detect non-rotational devices
Date: Thu, 23 Apr 2009 11:25:31 -0600	[thread overview]
Message-ID: <20090423172531.GQ1926@parisc-linux.org> (raw)
In-Reply-To: <49F07DAD.7080107@garzik.org>

On Thu, Apr 23, 2009 at 10:39:41AM -0400, Jeff Garzik wrote:
> Matthew Wilcox wrote:
> >On Thu, Apr 23, 2009 at 02:10:13PM +0000, James Bottomley wrote:
> >>I'm with Jeff on this one.  We had an identically similar problem with
> >>REPORT LUNS, which, today is the basis of SCSI discovery.
> >
> >Yes, REPORT LUNS is quite essential.
> >
> >It's not exactly in the same category as reporting device form factor
> >and rotational speed.  If REPORT LUNS is wrong, we're in really deep
> >trouble.  If device form factr is wrong ... umm ... nothing much happens.
> >If rotational speed is wrong, we might have a suboptimal IO pattern.
> 
> If the general attitude is "oh, that info might be wrong", why will app 
> developers bother at all?

Any info might be wrong.  SCSI drives might return the wrong thing in
EVPD b1 too.  We don't check that in the kernel, we just return it to
user space.

> >It's also fixable by udev.
> 
> By that logic we should leave it to udev to handle the ata_version <= 7 
> stuff, since that is the early adopter special case.

I'm perfectly fine with never setting this bit in the kernel and having
udev handle all cases, including checking for garbage.

-- 
Matthew Wilcox				Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."

  reply	other threads:[~2009-04-23 17:25 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-04-23  5:29 [PATCH 0 of 8] I/O topology patch kit Martin K. Petersen
2009-04-23  5:29 ` [PATCH 1 of 8] block: Expose stacked device queues in sysfs Martin K. Petersen
2009-04-23  5:29 ` Martin K. Petersen
2009-04-23  5:29 ` [PATCH 2 of 8] block: Export I/O topology for block devices and partitions Martin K. Petersen
2009-04-23 10:51   ` Jens Axboe
2009-04-23 11:49     ` Matthew Wilcox
2009-04-23 11:55       ` Jens Axboe
2009-04-23 13:22         ` Matthew Wilcox
2009-04-23 13:30           ` Matthew Wilcox
2009-04-23 13:17     ` Martin K. Petersen
2009-04-23 18:13     ` Konrad Rzeszutek
2009-04-23 18:26       ` Ric Wheeler
2009-04-23 18:44         ` Matthew Wilcox
2009-04-23 18:34       ` Martin K. Petersen
2009-04-23  5:29 ` [PATCH 3 of 8] MD: Use new topology calls to indicate alignment and I/O sizes Martin K. Petersen
2009-04-23  5:29 ` [PATCH 4 of 8] sd: Physical block size and alignment support Martin K. Petersen
2009-04-23 16:37   ` Konrad Rzeszutek
2009-04-23 18:25     ` Martin K. Petersen
2009-04-23 18:44       ` Konrad Rzeszutek
2009-04-23 19:02         ` Martin K. Petersen
2009-04-23  5:29 ` Martin K. Petersen
2009-04-23  5:29 ` [PATCH 5 of 8] sd: Detect non-rotational devices Martin K. Petersen
2009-04-23 10:52   ` Jens Axboe
2009-04-23 11:09     ` Jeff Garzik
2009-04-23 11:13       ` Jens Axboe
2009-04-23 11:22         ` Jeff Garzik
2009-04-23 11:38       ` Matthew Wilcox
2009-04-23 11:58         ` Jeff Garzik
2009-04-23 12:03           ` Jens Axboe
2009-04-23 13:16         ` Martin K. Petersen
2009-04-23 13:33           ` Jeff Garzik
2009-04-23 14:10             ` James Bottomley
2009-04-23 14:16               ` Matthew Wilcox
2009-04-23 14:39                 ` Jeff Garzik
2009-04-23 17:25                   ` Matthew Wilcox [this message]
2009-04-23 17:37                     ` James Bottomley
2009-04-23  5:29 ` [PATCH 6 of 8] sd: Block limits VPD support Martin K. Petersen
2009-04-23  5:29 ` [PATCH 7 of 8] scsi_debug: Add support for physical block exponent and alignment Martin K. Petersen
2009-04-23  5:29 ` [PATCH 8 of 8] libata: Report disk alignment and physical block size Martin K. Petersen
2009-04-23 13:46   ` Matthew Wilcox
2009-04-23 14:05     ` Martin K. Petersen
2009-04-23  5:29 ` Martin K. Petersen

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