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Message-ID: <58cb370e05070413472629dd58@mail.gmail.com>
Date: Mon, 4 Jul 2005 22:47:39 +0200
From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Reply-To: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
To: Al Boldi <a1426z@gawab.com>
Subject: Re: [git patches] IDE update
Cc: Ondrej Zary <linux@rainbow-software.org>,
       Linus Torvalds <torvalds@osdl.org>, linux-ide@vger.kernel.org,
       linux-kernel@vger.kernel.org
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On 7/4/05, Al Boldi <a1426z@gawab.com> wrote:
> Bartlomiej Zolnierkiewicz wrote: {
> > >
> > >>On 7/4/05, Al Boldi <a1426z@gawab.com> wrote:
> > >>Hdparm -tT gives 38mb/s in 2.4.31
> > >>Cat /dev/hda > /dev/null gives 2% user 33% sys 65% idle
> > >>
> > >>Hdparm -tT gives 28mb/s in 2.6.12
> > >>Cat /dev/hda > /dev/null gives 2% user 25% sys 0% idle 73% IOWAIT
> > >>
> > >>It feels like DMA is not being applied properly in 2.6.12.
> > >
> > > Same on 2.6.10,11,12.
> > > No errors though, only sluggish system.
> 
> What about earlier kernels?
> Please try to narrow down the problem to a specific kernel version.
> }
> 
> Don't know about 2.6.0-2.6.9, but 2.4.31 is ok.

2.4 -> 2.6 means zillions of changes.
 
> Bartlomiej,
> When you compare 2.4.31 with 2.6.12 don't you see this problem on your
> machine?

Unfortunately I've never encountered this problem on any machine.

> If you have a fast system the slowdown won't show, but your IOWAIT will be
> higher anyway!

AFAIK high iowait is a known block layer problem

> It feels like running on PIO instead of DMA.