linux-kernel - Re: [PATCH 7/7] Cpuidle: poll state can measure residency

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Message-ID: <530C76E7.8090607@linaro.org>
Date:	Tue, 25 Feb 2014 11:56:39 +0100
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	Tuukka Tikkanen <tuukka.tikkanen@...aro.org>,
	linux-pm@...r.kernel.org, rjw@...ysocki.net
CC:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 7/7] Cpuidle: poll state can measure residency

On 02/24/2014 07:29 AM, Tuukka Tikkanen wrote:
> For some platforms, a poll state is inserted in the cpuidle driver states.
> The flags for the state do not indicate that timekeeping is not affected.
> As the state does not do anything apart from calling cpu_relax(), the
> times returned by ktime_get should remain valid. Add the missing flag.

Yes, but it is done with the interrupt enabled, so the interrupt handler 
+ softirq handler times will be accounted in the residency time.

I am not sure adding this flag is good.

> Signed-off-by: Tuukka Tikkanen <tuukka.tikkanen@...aro.org>
> ---
>   drivers/cpuidle/driver.c |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c
> index 06dbe7c..136d6a2 100644
> --- a/drivers/cpuidle/driver.c
> +++ b/drivers/cpuidle/driver.c
> @@ -209,7 +209,7 @@ static void poll_idle_init(struct cpuidle_driver *drv)
>   	state->exit_latency = 0;
>   	state->target_residency = 0;
>   	state->power_usage = -1;
> -	state->flags = 0;
> +	state->flags = CPUIDLE_FLAG_TIME_VALID;
>   	state->enter = poll_idle;
>   	state->disabled = false;
>   }
>


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