Re: [patch] CFS scheduler, -v14

[Li Yu]

Ingo Molnar wrote:
> * Li Yu <raise.sail@xxxxxxxxx> wrote:
>
>   
> > static void distribute_fair_add(struct rq *rq, s64 delta)
> > {
> >    struct task_struct *curr = rq->curr;
> >    s64 delta_fair = 0;
> >
> >    if (!(sysctl_sched_load_smoothing & 32))
> >        return;
> >
> >    if (rq->nr_running) {
> >        delta_fair = div64_s(delta, rq->nr_running);
> >        /*
> >         * The currently running task's next wait_runtime value does
> >         * not depend on the fair_clock, so fix it up explicitly:
> >         */
> >        add_wait_runtime(rq, curr, -delta_fair);
> >        rq->fair_clock -= delta_fair;
> >    }
> > }
> >
> > See this line:
> >
> >        delta_fair = div64_s(delta, rq->nr_running);
> >
> > Ingo, should we be replace "rq->nr_running" with "rq->raw_load_weight" 
> > here?
> >     
>
> that would break the code. The handling of sleep periods is basically 
> heuristics and using nr_running here appears to be 'good enough' in 
> practice.
>
>   
Thanks,  I am wrong at seeing the delta variable is represented by 
virtual time unit. if the code does as I said, the delta_fair may be too 
small to meanless.

Also, I have want to know what's real meaning of     

   add_wait_runtime(rq, curr, delta_mine - delta_exec);

in update_curr(), IMHO, it should be

   add_wait_runtime(rq, curr, delta_mine - delta_fair);

Is this just another heuristics? or my opinion is wrong again? :-)

Good luck.

- Li Yu





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