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SubjectRe: [patch] new scheduler
Date
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Rik van Riel wrote:
>
> No. Interactive processes that don't use up their time slice
> before jiffies reaches p->defer will get their time slice
> fully reinstated in wake_up_process().

Ah, but this is bad.

On SunOS, I had a program that did:

for (i=0;i<SOMELARGECONSTANT;i++) {
do_something ();
if (i % SOMECONSTANT == 0) usleep (10);
}

The constant would be tuned to fill about 80 or 90% of a timer
tick. The program would run for 2.5 times as much real-time compared
to when the "usleep" wasn't there, but it would get accounted for less
than 10% of the original CPU time!

If I understand you correctly, when I'm competing with another batch
process for CPU, I'd normally get only 50% of the CPU. With your patch
I could now boost that to 80 or 90% by giving up the CPU (usleep) just
before my timeslice is over?

Roger.


--
** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2137555 **
*-- BitWizard writes Linux device drivers for any device you may have! --*
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