From: Lee Revell <rlrevell@joe-job.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Mark Lord <lkml@rtr.ca>,
bzolnier@milosz.na.pl, Greg Stark <gsstark@mit.edu>,
Denis Vlasenko <vda@port.imtp.ilyichevsk.odessa.ua>,
Todd Poynor <tpoynor@mvista.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
tim.bird@am.sony.com, dsingleton@mvista.com
Subject: Re: [PATCH] Configure IDE probe delays
Date: Wed, 01 Sep 2004 15:08:39 -0400 [thread overview]
Message-ID: <1094065718.1970.39.camel@krustophenia.net> (raw)
In-Reply-To: <1094051215.2777.15.camel@localhost.localdomain>
On Wed, 2004-09-01 at 11:06, Alan Cox wrote:
> On Mer, 2004-09-01 at 14:20, Mark Lord wrote:
> > LBA48 is only needed when (1) the sector count is greater than 256,
> > and/or (2) the ending sector number >= (1<<28).
>
> I've played with this a bit and in the -ac IDE code it can drop back
> to LBA28 for devices that are small enough not to need LBA48 when the
> controller only supports PIO for LBA48 modes (eg some ALi) as 2.4-ac
> did.
>
> > I regularly include this optimisation in the drivers I have been
> > working on since LBA48 first appeared.
>
> It isn't always a win. You get cut down to 256 sectors per I/O which for
> some workloads has a cost and you need to factor that into the command
> issue choice as well as the last sector number being accessed.
>
I have never been able to measure a decrease in disk throughput in any
disk benchmark with 256 sectors per I/O vs. 1024. This is a modestly
powered desktop with a single drive though. What kinds of workloads
would you expect to be affected by this?
Lee
next prev parent reply other threads:[~2004-09-01 19:08 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-07-30 19:11 [PATCH] Configure IDE probe delays Todd Poynor
2004-07-30 21:36 ` Lee Revell
2004-07-30 22:35 ` Alan Cox
2004-07-31 0:12 ` Lee Revell
[not found] ` <200407311434.59604.vda@port.imtp.ilyichevsk.odessa.ua>
2004-07-31 18:00 ` Lee Revell
2004-08-27 17:45 ` Greg Stark
2004-08-27 17:53 ` Lee Revell
2004-08-27 18:05 ` Bartlomiej Zolnierkiewicz
2004-08-27 18:08 ` Lee Revell
2004-08-27 18:59 ` Bartlomiej Zolnierkiewicz
2004-09-01 13:20 ` Mark Lord
2004-09-01 14:43 ` Jeff Garzik
2004-09-01 15:30 ` Mark Lord
2004-09-01 15:36 ` Mark Lord
2004-09-01 19:36 ` Lee Revell
2004-09-01 18:42 ` Alan Cox
2004-09-01 15:06 ` Alan Cox
2004-09-01 19:08 ` Lee Revell [this message]
2004-09-02 16:04 ` Mark Lord
2004-09-01 15:40 ` Bartlomiej Zolnierkiewicz
2004-07-31 18:06 ` Lee Revell
2004-07-31 19:35 ` Alan Cox
2004-07-31 21:35 ` Lee Revell
2004-07-31 21:44 ` Jeff Garzik
2004-07-31 22:12 ` Lee Revell
2004-08-04 17:30 ` Anthony de Boer
2004-08-05 21:39 ` Tim Bird
2004-07-31 0:54 ` Jeff Garzik
2004-08-03 17:47 ` Mark Lord
2004-08-06 15:48 ` Jeff Garzik
2004-08-06 19:29 ` Tim Bird
2004-08-06 20:46 ` Todd Poynor
2004-08-02 21:56 ` Tim Bird
2004-08-02 21:01 ` Alan Cox
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