Re: hdparm and DMA
On Mon, Nov 18, 2002 at 04:16:57PM +0100, Emil Pedersen wrote:
> > /dev/hda:
> > Timing buffer-cache reads: 128 MB in 0.46 seconds =278.26 MB/sec
> > Timing buffered disk reads: 64 MB in 16.12 seconds = 3.97 MB/sec
>
> THIS is ok, without dma performance is lousy, but I really don't
> understand why you can't turn it on (or get better perf when you do)!
On my system hdparm complains: "Permission denied" when I try to turn
on DMA.
My system gets a whopping 5.33Mb per second.
> > Thus all the same as before whether turned on or off. I also tried
> > setting MultiSect to max of 16 (which hdparm -i told me it could do),
> > but this didn't change things either.
> >
> > So are the read times as expected for an IDE ATA133, 7200RPM, 40GB drive?
>
> Certainly not. Bellow is what I got from my IBM 7200 rpm disk, (using
> UDMA66):
My disk gets 48Mb per second in a different system. I have a 7200 RPM
WD800 (the one with the lowsy 2M buffer).
Roger.
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