Re: Linux scheduler and goodness calculation

[Davide Libenzi]

> Whilst we (on this cpu) are going through the runqueue and selecting the
> process with the highest goodness, someone else (schedule() running on
> another cpu) could be going through the entire set of processes and
> recalculating their dynamic priorities (p->counter) because schedule drops
> runqueue_lock at recalculate label in schedule(), presumably for
> performance reasons, i.e. to let another schedule() execute as soon as
> possible while we may be spending ages in for_each_task() loop.
>
> Isn't this inconsistent? This means that what is selected as "highest
> goodness" on this cpu is not necessarily the "fair value" because it is
> based on wrong values of p->counter of the tasks examined (i.e. on the
> runqueue).

The probability that it happens multiplied by the system impact bring to
zero
the effect.

Davide

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