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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Mark Lord <lkml@rtr.ca>
Cc: bzolnier@milosz.na.pl, Lee Revell <rlrevell@joe-job.com>,
	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 16:06:57 +0100	[thread overview]
Message-ID: <1094051215.2777.15.camel@localhost.localdomain> (raw)
In-Reply-To: <4135CC9E.5060905@rtr.ca>

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.

Alan


  parent reply	other threads:[~2004-09-01 16:30 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 [this message]
2004-09-01 19:08                       ` Lee Revell
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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