>On Tue, 11 May 1999, Andrea Arcangeli wrote:
>>
>> The reschedule_idle() in schedule_tail is there only to handle the case
>> where the `prev' task is been rescheduled due a reschedule_idle()
>> call (##).
>>
>> But if it's been rescheduled due a reschedule_idle() it means that:
>>
>> 1) there are no idle cpu in the system
>> 2) the prev task was in general the less priority one
>
>wrong. We actively _preempt_ processes on other CPUs, this means that a
If I understand well the only wrong thing I said is point (2). But if you
would read better my email I stated clearly that point (2) it not the pure
reality, but instead I said that it's a very good approximation of the
pure reality.
>preempted process has all rights to try to replace even lesser priority
>processes on other CPUs. Your problem might be that you are thinking in
You should rereadd my previous email. I never said it's useless, I have
said that it's not worthwile.
You mean that a preemted process has all rights to preempt a even lesser
priority CPU. But ask you _why_ such process is been preempted. Simply
because in general we can see it as the _less_ priority one.
Also think that the preemted task has prev->processor pointing the only
not reschedulable CPU.
>terms of dual-CPU boxes, i'm using a quad one. (btw, even on a dual box it
I am not thinking at dual-CPU I always think without limit of CPU.
>is possible to 'push' a process to another CPU, although it's not the
>common case)
I agree that it's possible (I _never_ said the opposite) but my only
comment is and was that I am not sure it's really worthwhile. I also said and
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_.
Andrea Arcangeli
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