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SubjectRe: [patch] new scheduler

On Tue, 11 May 1999, Andrea Arcangeli wrote:

> >not necesserily, it might as well just be replaced by a RT process ...
>
> If the `prev' process is RT and the `prev' task is been preemted it means
> that all other CPUs are just running RT task too. So it wouldn't be
> worthwhile again.

Just think about it for a second: if you preempt a RT task with another RT
task (yes this is possible, and yes, this is a RL example), then we
immediately want to 'push' that RT task to another CPU. Also there are
other, non-RT cases where 'pushing' a process to another processor makes
sense. (just think about different static process priorities for a second)

> >> I repeat that as global design I prefer to have such call in schedule_tail
> >> even if according to me it's only a performance _hit_.
^^^^^^^^^^^^^^^^^^^^
> >
> >it is not a performance hit at all because most processes reschedule
> >'voluntarily', ie. they get removed from the runqueue.
>
> I just said you that in such case the call is not needed. [...]

then why do you say it's a performance hit? It's something we need for
correctness, it doesnt affect the common case, where is your problem?

-- mingo


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