Re: [PATCH 3/6] cpuidle: menu: Get rid of first_idx from menu_select()

Peter Zijlstra
2018-10-04T07:46:27Z

On Tue, Oct 02, 2018 at 11:44:06PM +0200, Rafael J. Wysocki wrote:
> idx = -1;
> - for (i = first_idx; i < drv->state_count; i++) {
> + for (i = 0; i < drv->state_count; i++) {
> struct cpuidle_state *s = &drv->states[i];
> struct cpuidle_state_usage *su = &dev->states_usage[i];
>
> if (s->disabled || su->disable)
> continue;
> +
> if (idx == -1)
> idx = i; /* first enabled state */
> +
> if (s->target_residency > predicted_us) {
> + /*
> + * Use a physical idle state, not busy polling, unless
> + * a timer is going to trigger really really soon.
> + */
> + if ((drv->states[idx].flags & CPUIDLE_FLAG_POLLING) &&
> + i == idx + 1 && latency_req > s->exit_latency &&
> + data->next_timer_us > max_t(unsigned int, 20,
> + s->target_residency)) {

Not new in this patch, but this is where I really noticed it; that 20,
should that not be something like: POLL_IDLE_TIME_LIMIT / NSEC_PER_USEC
?

> + idx = i;
> + break;
> + }
> if (predicted_us < TICK_USEC)
> break;
>
>