Re: [PATCH 6/7] KVM-GST: adjust scheduler cpu power

Peter Zijlstra
2011-06-14T10:42:27Z

On Mon, 2011-06-13 at 19:31 -0400, Glauber Costa wrote:
> @@ -1981,12 +1987,29 @@ static void update_rq_clock_task(struct rq
> *rq, s64 delta)
>
> rq->prev_irq_time += irq_delta;
> delta -= irq_delta;
> +#endif
> +#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
> + if (static_branch((&paravirt_steal_rq_enabled))) {

Why is that a different variable from the touch_steal_time() one?

> +
> + steal = paravirt_steal_clock(cpu_of(rq));
> + steal -= rq->prev_steal_time_acc;
> +
> + rq->prev_steal_time_acc += steal;

You have this addition in the wrong place, when you clip:

> + if (steal > delta)
> + steal = delta;

you just lost your steal delta, so the addition to prev_steal_time_acc
needs to be after the clip.

> + delta -= steal;
> + }
> +#endif
> +
> rq->clock_task += delta;
>
> - if (irq_delta && sched_feat(NONIRQ_POWER))
> - sched_rt_avg_update(rq, irq_delta);
> + if ((irq_delta + steal) && sched_feat(NONTASK_POWER))
> + sched_rt_avg_update(rq, irq_delta + steal);
> }