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SubjectRe: [PATCH v2 1/2] cpuidle : auto-promotion for cpuidle states
Date
Hi,

Sorry, just realised another thing I wanted to ask:

> @@ -442,6 +442,26 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
> }
> }
>
>
> +#ifdef CPUIDLE_FLAG_AUTO_PROMOTION

Why is this based on CPUIDLE_FLAG_ rather than CONFIG_CPU_IDLE_? Won't
this always be true, given that the flag is defined regardless of the
config option in the header?

> + if (drv->states[idx].flags & CPUIDLE_FLAG_AUTO_PROMOTION) {
> + /*
> + * Timeout is intended to be defined as sum of target residency
> + * of next available state, entry latency and exit latency. If
> + * time interval equal to timeout is spent in current state,
> + * and if it is a shallow lite state, we may want to auto-
> + * promote from such state.
> + */

Regards,
Daniel

> + for (i = idx + 1; i < drv->state_count; i++) {
> + if (drv->states[i].disabled ||
> + dev->states_usage[i].disable)
> + continue;
> + *timeout = drv->states[i].target_residency +
> + 2 * drv->states[i].exit_latency;
> + break;
> + }
> + }
> +#endif
> +
> return idx;
> }
>
> diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
> index 3b3947232..84d76d1ec 100644
> --- a/include/linux/cpuidle.h
> +++ b/include/linux/cpuidle.h
> @@ -72,6 +72,13 @@ struct cpuidle_state {
> #define CPUIDLE_FLAG_POLLING BIT(0) /* polling state */
> #define CPUIDLE_FLAG_COUPLED BIT(1) /* state applies to multiple cpus */
> #define CPUIDLE_FLAG_TIMER_STOP BIT(2) /* timer is stopped on this state */
> +/*
> + * State with only and only fast state bit set don't even lose user context.
> + * But such states prevent other sibling threads from thread folding benefits.
> + * And hence we don't want to stay for too long in such states and want to
> + * auto-promote from it.
> + */
> +#define CPUIDLE_FLAG_AUTO_PROMOTION BIT(3)
>
> struct cpuidle_device_kobj;
> struct cpuidle_state_kobj;
> @@ -243,7 +250,8 @@ struct cpuidle_governor {
>
> int (*select) (struct cpuidle_driver *drv,
> struct cpuidle_device *dev,
> - bool *stop_tick);
> + bool *stop_tick, unsigned long
> + *timeout);
> void (*reflect) (struct cpuidle_device *dev, int index);
> };
>
> --
> 2.17.1

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