From: Matthew Wilcox <matthew@wil.cx>
To: Tejun Heo <htejun@gmail.com>
Cc: Grant Grundler <grundler@google.com>,
James Bottomley <James.Bottomley@hansenpartnership.com>,
linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org
Subject: Re: libata / scsi separation
Date: Wed, 10 Dec 2008 09:01:18 -0700 [thread overview]
Message-ID: <20081210160118.GX25548@parisc-linux.org> (raw)
In-Reply-To: <493FE15C.4060907@gmail.com>
On Thu, Dec 11, 2008 at 12:33:48AM +0900, Tejun Heo wrote:
> And yeap we definitely should try to do that too but I don't think
> RW_SG would be as useless as jumbo frames (much less compatibility
> problem and no loss of functionality), and the actual hardware
> overhead of issuing separate commands for each 4k segment is way
> higher than anything we do along the block and low level driver layers
> in terms of IO access, host bus and ATA (or SAS) bus overhead.
You're probably right that there's high overhead at the hardware level,
and we can't do anything about that. There is some evidence that Linux
is the limiting factor in SSD performance right now due to not being
able to get enough commands to the device.
--
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."
next prev parent reply other threads:[~2008-12-10 16:01 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-03 1:38 [PATCH] remove ide-scsi FUJITA Tomonori
2008-12-03 10:06 ` Christoph Hellwig
2008-12-03 13:31 ` Willem Riede
2008-12-03 13:55 ` Matthew Wilcox
2008-12-03 14:02 ` Alan Cox
2008-12-03 15:09 ` James Bottomley
2008-12-06 6:12 ` Pete Zaitcev
2008-12-06 14:06 ` Bartlomiej Zolnierkiewicz
2008-12-06 14:51 ` Bartlomiej Zolnierkiewicz
2008-12-06 15:06 ` Alan Cox
2008-12-06 16:29 ` Bartlomiej Zolnierkiewicz
2008-12-06 15:25 ` Willem Riede
2008-12-06 15:59 ` Bartlomiej Zolnierkiewicz
2008-12-06 17:00 ` Dan Noé
2008-12-06 21:41 ` Bartlomiej Zolnierkiewicz
2008-12-06 22:24 ` Alan Cox
2008-12-06 22:52 ` Sergei Shtylyov
2008-12-06 23:02 ` Alan Cox
2008-12-06 23:19 ` Sergei Shtylyov
2008-12-06 23:32 ` Alan Cox
2008-12-07 0:08 ` Sergei Shtylyov
2008-12-07 11:40 ` Alan Cox
2008-12-07 14:46 ` Sergei Shtylyov
2008-12-07 15:04 ` James Bottomley
2008-12-07 15:21 ` Sergei Shtylyov
2008-12-09 22:21 ` libata / scsi separation Matthew Wilcox
2008-12-09 22:38 ` James Bottomley
2008-12-10 3:37 ` Matthew Wilcox
2008-12-10 1:54 ` Tejun Heo
2008-12-10 2:29 ` Grant Grundler
2008-12-10 2:47 ` Tejun Heo
2008-12-10 3:23 ` Grant Grundler
2008-12-10 3:44 ` Tejun Heo
2008-12-10 15:24 ` Matthew Wilcox
2008-12-10 15:33 ` Tejun Heo
2008-12-10 16:01 ` Matthew Wilcox [this message]
2008-12-10 17:11 ` Grant Grundler
2008-12-10 17:21 ` Grant Grundler
2008-12-07 0:19 ` [PATCH] remove ide-scsi Sergei Shtylyov
2008-12-07 9:59 ` Sergei Shtylyov
2008-12-07 10:41 ` Sergei Shtylyov
2008-12-09 21:41 ` Matthew Wilcox
2008-12-10 17:46 ` Sergei Shtylyov
2008-12-06 23:28 ` Jeff Garzik
2008-12-06 23:42 ` Sergei Shtylyov
2008-12-06 23:48 ` Jeff Garzik
2008-12-07 3:36 ` Yinghai Lu
2008-12-07 4:17 ` Jeff Garzik
2008-12-07 5:07 ` Yinghai Lu
2008-12-07 11:00 ` Sergei Shtylyov
2008-12-09 19:59 ` Mark Lord
2008-12-09 20:07 ` Jeff Garzik
2008-12-09 21:04 ` James Bottomley
2008-12-06 23:45 ` Bartlomiej Zolnierkiewicz
2008-12-06 23:50 ` Jeff Garzik
2008-12-06 23:40 ` Bartlomiej Zolnierkiewicz
2008-12-06 23:51 ` Alan Cox
2008-12-07 0:56 ` Bartlomiej Zolnierkiewicz
2008-12-07 1:14 ` Alan Cox
2008-12-07 10:32 ` Sergei Shtylyov
2008-12-06 23:51 ` Jeff Garzik
2008-12-06 22:33 ` Al Viro
2008-12-06 23:13 ` Bartlomiej Zolnierkiewicz
2008-12-06 23:17 ` Willem Riede
2008-12-07 0:09 ` Al Viro
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