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SubjectRe: Scheduling the highest priority task

* Martin Roehricht <ml@felicis.org> wrote:

> On 08/02/2007 05:19 PM, Ingo Molnar wrote:
> >* Martin Roehricht <ml@felicis.org> wrote:
> >
> >>That's fine with me, that within the same priority-queue any task can
> >>be chosen. But assume two tasks with highly different priorities, such
> >>as 105 and 135 are scheduled on the same processor and one of them is
> >>now to be migrated -- shouldn't be the queue with task P=105
> >>considered first for migration by this code? Both tasks would use
> >>different queues with their own linked lists, right?
> >
> >yes. What makes you believe that the lower priority one (prio 135) is
> >chosen? [ as i said before, that will only be chosen if all tasks in the
> >higher-priority queue (prio 105) are either already running on a CPU or
> >have recently run so that the cache-hot logic skips them. ]
>
> This believe is primarily based on my observations of multiple
> benchmark runs and also on your statement earlier: »in the SMP
> migration code, the 'old scheduler' indeed picks the lowest priority
> one«.

oh, sorry, that was meant to be the 'highest priority one' :-/

so i think you got it all right, i just typoed that first sentence.

Ingo
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