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SubjectRe: How does on get a HD running at a descent speed
Zlatko Calusic wrote:
>
> jan gyselinck <JAN.GYSELINCK@student.kuleuven.ac.be> writes:
...
> > If anyone knows how I could get some descent speed with my HD,
> > say it (I read the list, no need to CC to me).

The original posting mentioned DOS using mode3,
but the numbers shown (240us/cycle) were slower than mode3 (180ns).

> My magic recipe is:
>
> hdparm -u1 -m16 -a16 -A1 -c1 /dev/hda
>
> Though your mileage may vary, of course.
...
> Notice how %CPU columns have lower values, even with better I/O
> throughput. Tested disk is IBM DAQA33240 (3.2GB).

The %CPU is not a meaningful measure here, though it probably
does reflect lower overall CPU usage in this example (think about it..
with an infinitely fast disk (eg. ramdrive), CPU will be 100% simply
because I/O takes no time..)

In this case, the reduced CPU is attributable to the -m16 parameter,
which basically cuts the IDE interrupt overhead down to as little
as (in this case) 1/16th that of the default setup.
--
mlord@pobox.com
The Linux IDE guy

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