Re: [PATCH 3/3] cpuidle, ACPI: remove unused CPUIDLE_FLAG_TIME_INVALID

[Daniel Lezcano <daniel.lezcano@linaro.org>]

On 12/16/2014 07:52 AM, Len Brown wrote:
> From: Len Brown <len.brown@intel.com>
>
> CPUIDLE_FLAG_TIME_INVALID is no longer checked
> by menu or ladder cpuidle governors, so don't
> bother setting or defining it.
>
> It was originally invented to account for the fact that
> acpi_safe_halt() enables interrupts to invoke HLT.
> That would allow interrupt service routines to be included
> in the last_idle duration measurements made in cpuidle_enter_state(),
> potentially returning a duration much larger than reality.
>
> But menu and ladder can gracefully handle erroneously large duration
> intervals without checking for CPUIDLE_FLAG_TIME_INVALID.
> Further, if they don't check CPUIDLE_FLAG_TIME_INVALID, they
> can also benefit from the instances when the duration interval
> is not erroneously large.
>
> Signed-off-by: Len Brown <len.brown@intel.com>
> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>

Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>


> ---
>   drivers/acpi/processor_idle.c | 2 --
>   include/linux/cpuidle.h       | 3 ---
>   2 files changed, 5 deletions(-)
>
> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> index 4995365..87b704e 100644
> --- a/drivers/acpi/processor_idle.c
> +++ b/drivers/acpi/processor_idle.c
> @@ -985,8 +985,6 @@ static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
>   		state->flags = 0;
>   		switch (cx->type) {
>   			case ACPI_STATE_C1:
> -			if (cx->entry_method != ACPI_CSTATE_FFH)
> -				state->flags |= CPUIDLE_FLAG_TIME_INVALID;
>
>   			state->enter = acpi_idle_enter_c1;
>   			state->enter_dead = acpi_idle_play_dead;
> diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
> index a07e087..ab70f3b 100644
> --- a/include/linux/cpuidle.h
> +++ b/include/linux/cpuidle.h
> @@ -53,7 +53,6 @@ struct cpuidle_state {
>   };
>
>   /* Idle State Flags */
> -#define CPUIDLE_FLAG_TIME_INVALID	(0x01) /* is residency time measurable? */
>   #define CPUIDLE_FLAG_COUPLED	(0x02) /* state applies to multiple cpus */
>   #define CPUIDLE_FLAG_TIMER_STOP (0x04)  /* timer is stopped on this state */
>
> @@ -89,8 +88,6 @@ DECLARE_PER_CPU(struct cpuidle_device, cpuidle_dev);
>   /**
>    * cpuidle_get_last_residency - retrieves the last state's residency time
>    * @dev: the target CPU
> - *
> - * NOTE: this value is invalid if CPUIDLE_FLAG_TIME_INVALID is set
>    */
>   static inline int cpuidle_get_last_residency(struct cpuidle_device *dev)
>   {
>


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