Re: [PATCH] scheduler cleanup
Artur Skawina (skawina@geocities.com)
Wed, 13 Oct 1999 04:33:29 +0100
Andrea Arcangeli wrote:
>
> I had a fast look at the patch and one thing looks obviously wrong:
>
> + * A thread calling sched_yield() wants to give up its timeslice and let
> + * other equal priority threads to run.
> + * We optimize by ignoring the request completely when the number of
> + * currently runnable processes is <= the number of available CPUs.
>
> You can't expect the other running tasks to reschedule idle CPUs as they
> may be very fast tasks that needs to run on your CPU as they don't want to
> trash the CPU cache. So you must _always_ reschedule if SCHED_YIELD is
> asked.
hmm, while the check certainly isn't necessary (it's supposed to help
in pathological situations when sys_sched_yield() is needlessly called,
and mainly reduce lock contention), i don't see the problem...
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