Re: [PATCH] O12.2int for interactivity

Timothy Miller
2003-08-14T19:45:56Z

William Lee Irwin III wrote:
> On Thu, 14 Aug 2003 16:09, William Lee Irwin III wrote:
>
>>>"scale" on which scheduling events should happen, and as tasks become
>>>more cpu-bound, they have longer timeslices, so that two cpu-bound
>>>tasks of identical priority will RR very slowly and have reduced
>>>context switch overhead, but are near infinitely preemptible by more
>>>interactive or short-running tasks.
>>
>
> On Thu, Aug 14, 2003 at 04:59:33PM +1000, Con Kolivas wrote:
>
>>Actually the timeslice handed out is purely dependent on the static priority,
>>not the priority it is elevated or demoted to by the interactivity estimator.
>>However lower priority tasks (cpu bound ones if the estimator has worked
>>correctly) will always be preempted by higher priority tasks (interactive
>>ones) whenever they wake up.
>
>
> So it is; the above commentary was rather meant to suggest that the
> lengthening of timeslices in conventional arrangements did not penalize
> interactive tasks, not to imply that priority preemption was not done
> at all in the current scheduler.

If my guess from my previous email was correct (that is pri 5 gets
shorter timeslide than pri 6), then that means that tasks of higher
static priority have are penalized more than lower pri tasks for expiring.

Say a task has to run for 15ms. If it's at a priority that gives it a
10ms timeslice, then it'll expire and get demoted. If it's at a
priority that gives it a 20ms timeslice, then it'll not expire and
therefore get promoted.

Is that fair?