Re: IDE-DMA strangeness (another one)

Rik van Riel (
Wed, 2 Dec 1998 05:21:45 +0100 (CET)

On Tue, 1 Dec 1998, Alex Buell wrote:
> On Tue, 1 Dec 1998, Rik van Riel wrote:
> > With this move I saw in improvement (hdparm -t) from 3
> > to 8.4 (!) MB/second... Now I wonder what kind of bug
> > in the Linux I/O subsystem could hold performance back
> > _that_ badly.
> Makes a lot of sense if your old IDE disk was PIO only and the newer
> IDE uses DMA.

All IDE devices in my box are DMA2 capable.

> My machine exhibited the same speedup when I swapped around my old
> PIO IDE and my spankin' new UMDA IDE hard disks. (It's stuck in DMA
> though as PIIX3 chipset doesn't support UDMA - guess I'll have to
> buy a Promise UDMA33 controller someday!)

I'm working with an (apparently buggy) PIIX mobo. It's
certainly fast enough not to be saturated by the HDs
or the CD.


Rik -- now completely used to dvorak kbd layout...
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