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SubjectRe: Scheduling: interactive problems still there in 129
On Fri, 20 Nov 1998, Neil Conway wrote:

> This has been mentioned by many people so far (I seem to recall even
> seeing patches) but is still there in 129.

[SNIP]

> Now on a 2.1.129 SMP machine (2 cpus) I run two copies of the same
> CPU hog. Now my key-holding down gets lots of pauses, some short,
> some quite long (like the odd one is 100's of milliseconds)
> (measured by eye :-)).
>
> when I run say 3 CPU hogs on a 2 CPU machine, each of which needs
> say 1 minute of CPU time, and I start them maybe 2 seconds apart, I
> get the weird effect that the first one to start gets CONSISTENTLY
> more CPU time than the others

I guess I should fix reschedule_idle() to fix this.
I'll get working on this ASAP and I even have an
idea on how to fix the problem relatively inexpensively.

Note the /relatively/, since cache locality is quite
important when we want to achieve scalable SMP. To
properly implement things, we also need to take in
account things like the time the program left the
run queue, so I'll probably fix things in the context
of my scheduler_bigpatch...

> I presume this implies a sorting problem in the scheduler code ?

The current version of my scheduler_bigpatch doesn't
fix the reschedule_idle() thing, but it does contain
some other (more generic) fixes that should help you
with your problem.

cheers,

Rik -- slowly getting used to dvorak kbd layout...
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