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From: Willy Tarreau <>
To: Alan Cox <>
Subject: Re: [PATCH 0/2] libata: implement 32-bit transfers for PIO mode
Date: Mon, 18 Feb 2008 00:08:00 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <20080217223134.1c61809b@core>

On Sun, Feb 17, 2008 at 10:31:34PM +0000, Alan Cox wrote:
> > Thus, I have implemented the 32-bit mode to bring the performance back
> > to the level of the old IDE driver. I jumped from 1.5 MB/s to 2.5 MB/s,
> > which is an important difference at this level of performance, especially
> > when large files are read. The 32-bit mode is enabled using the ioctl
> > which is already implemented but only accepts a null value.
> Excellent, that has been on my TODO list for some time and I'd only
> gotten as far as putting into the ISA/VLB drivers rather than generally
> testing.
> I'm not however sure this should be a DFLAG but should be an alernative
> ata_data_xfer method - I say that because VLB needs to wrap it and some
> controllers have quirky rules for 32bit xfers. (Also some small number of
> pre ATA disks can't handle the different timing cycles from a 32bit ISA
> I/O being redirected their way).

Do you think this can cause any trouble considering that default setting
is not changed ? However, I agree that an alternative ata_data_xfer may
make it easier to always enable it on some controllers. Or maybe we should
keep it that way (since this function checks the ioctl value) and add a
pure 32-bit function for 32-bit enabled controllers ? I would say I have
no idea, it's clearly not my domain of expertise :-/

> Alan


      reply	other threads:[~2008-02-17 23:08 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-17 21:18 Willy Tarreau
2008-02-17 21:19 ` [PATCH 1/2] libata: implement ATA_IOC_GET_IO32/ATA_IOC_SET_IO32 ioctls Willy Tarreau
2008-04-17 19:49   ` Jeff Garzik
2008-04-17 19:46     ` Willy Tarreau
2008-04-17 22:02     ` [PATCH] libata: implement support for 32-bit PIO transfers Willy Tarreau
2008-02-17 21:20 ` [PATCH 2/2] " Willy Tarreau
2008-02-17 22:32   ` Alan Cox
2008-02-17 22:31 ` [PATCH 0/2] libata: implement 32-bit transfers for PIO mode Alan Cox
2008-02-17 23:08   ` Willy Tarreau [this message]

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