From: Jeremy Jackson <jerj@coplanar.net>
To: Tim Moore <timothymoore@bigfoot.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: UDMA 100 / PIIX4 question
Date: Mon, 19 Mar 2001 14:33:41 -0500 [thread overview]
Message-ID: <3AB65F14.26628BEF@coplanar.net> (raw)
In-Reply-To: <20010318165246Z131240-406+1417@vger.kernel.org> <3AB65C51.3DF150E5@bigfoot.com>
Tim Moore wrote:
> quintaq@yahoo.co.uk wrote:
> > I have an IBM DTLA 307030 (ATA 100 / UDMA 5) on an 815e board (Asus CUSL2), which has a PIIX4 controller.
> > ...
> > My problem is that (according to hdparm -t), I never get a better transfer rate than approximately 15.8 Mb/sec. I achieve this when DMA is enabled, - without it I fall back to about 5 Mb /sec. No amount of fiddling with other hdparm settings makes any difference.
> > ...
>
> 15MB/s for hdparm is about right.
Yes, since hdparm -t measures *SUSTAINED* transfers... the actual "head rate" of data reads from
disk surface. Only if you read *only* data that is alread in harddrive's cache will you get a speed
close to the UDMA mode of the drive/controller. The cache is around 1Mbyte, so for a split-second
re-read of some data....
>
>
> "...four IDE devices can be supported in Bus Master mode.
> PIIX4 contains support for "Ultra DMA/33" synchronous DMA
> compatible devices."
>
> http://developer.intel.com/design/intarch/techinfo/440BX/PIIX4_intro.htm
>
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next prev parent reply other threads:[~2001-03-19 19:41 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-03-18 16:53 UDMA 100 / PIIX4 question quintaq
2001-03-19 19:21 ` Tim Moore
2001-03-19 19:33 ` Jeremy Jackson [this message]
2001-03-19 20:17 ` Tim Moore
2001-03-19 22:22 ` quintaq
2001-03-20 16:11 ` Holger Lubitz
2001-03-20 17:33 ` Jeremy Jackson
2001-03-20 20:21 ` quintaq
2001-03-20 21:32 ` Mark Hahn
2001-03-21 9:56 ` quintaq
2001-03-21 16:26 ` quintaq
2001-03-21 16:38 ` Mike Dresser
2001-03-23 10:27 ` quintaq
2001-03-21 19:18 ` Tim Moore
2001-03-21 19:29 ` Andre Hedrick
2001-03-22 13:21 ` Holger Lubitz
2001-03-23 10:27 ` quintaq
2001-03-21 19:14 ` Tim Moore
2001-03-23 10:27 ` quintaq
2001-03-23 21:17 ` Tim Moore
2001-03-21 14:06 ` Holger Lubitz
2001-03-19 20:32 ` Mark Hahn
2001-03-19 21:51 ` Tim Moore
2001-03-19 19:55 ` Jeremy Jackson
2001-03-19 20:38 ` Tim Moore
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