Re: IDE-DMA strangeness (another one)

Alex Buell (
Tue, 1 Dec 1998 16:10:08 -0500 (EST)

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.

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!)

hdparm -t reports 9.6MB/s throughput for /dev/hda although hdparm -T
reports 33MB/s throughput, I don't quite believe that one though. :o)


 /\_/\  Legalise cannabis now! 
( o.o ) Grow some cannabis today! 
 > ^ <  Peace, Love, Unity and Respect to all.

Check out Linux lo-pc3035a 2.1.130 #10 Mon Nov 30 10:49:50 EST 1998 One Intel Pentium 166MHz processor, 66.36 total bogomips, 16M RAM System library 5.4.44

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