Re: [patch] CFS scheduler, -v8

Ingo Molnar
2007-05-02T18:15:40Z

* William Lee Irwin III <wli@holomorphy.com> wrote:

> > There is also p->wait_runtime which is taken into account when
> > calculating p->fair_key. So if p3 had waiting in runqueue for long
> > before, it can get to run quicker than 10ms later.
>
> Virtual time is time from the task's point of view, which it has spent
> executing. ->wait_runtime is a device to subtract out time spent on
> the runqueue but not running from what would otherwise be virtual time
> to express lag, whether deliberately or coincidentally. [...]

CFS is in fact _built around_ the ->wait_runtime metric (which, as its
name suggests already, expresses the precise lag a task observes
relative to 'ideal' fair execution), so what exactly makes you suspect
that this property of the ->wait_runtime metric might be 'coincidental'?
;-)

Ingo