Re: [REPORT] cfs-v4 vs sd-0.44

[Rogan Dawes <lists@dawes.za.net>]

Ingo Molnar wrote:

> static void
> yield_task_fair(struct rq *rq, struct task_struct *p, struct task_struct *p_to)
> {
>         struct rb_node *curr, *next, *first;
>         struct task_struct *p_next;
> 
>         /*
>          * yield-to support: if we are on the same runqueue then
>          * give half of our wait_runtime (if it's positive) to the other task:
>          */
>         if (p_to && p->wait_runtime > 0) {
>                 p->wait_runtime >>= 1;
>                 p_to->wait_runtime += p->wait_runtime;
>         }
> 
> the above is the basic expression of: "charge a positive bank balance". 
> 

[..]

> [note, due to the nanoseconds unit there's no rounding loss to worry 
> about.]

Surely if you divide 5 nanoseconds by 2, you'll get a rounding loss?

> 	Ingo

Rogan