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Date: Thu, 23 Oct 2014 12:47:23 -0400 (EDT)
From: Nicolas Pitre <nicolas.pitre@...aro.org>
To: Daniel Lezcano <daniel.lezcano@...aro.org>
cc: rjw@...ysocki.net, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org, peterz@...radead.org,
linaro-kernel@...ts.linaro.org, patches@...aro.org
Subject: Re: [PATCH V2 5/5] cpuidle: menu: Move the update function before
its declaration
On Thu, 23 Oct 2014, Daniel Lezcano wrote:
> In order to prevent a pointless forward declaration, just move the function
> at the beginning of the file.
>
> This patch does not change the behavior of the governor, it is just code
> reordering.
>
> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
Acked-by: Nicolas Pitre <nico@...aro.org>
> ---
> drivers/cpuidle/governors/menu.c | 149 +++++++++++++++++++--------------------
> 1 file changed, 74 insertions(+), 75 deletions(-)
>
> diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
> index 6ae8390..0ac76b1 100644
> --- a/drivers/cpuidle/governors/menu.c
> +++ b/drivers/cpuidle/governors/menu.c
> @@ -184,7 +184,6 @@ static inline int performance_multiplier(unsigned long nr_iowaiters, unsigned lo
>
> static DEFINE_PER_CPU(struct menu_device, menu_devices);
>
> -static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev);
>
> /* This implements DIV_ROUND_CLOSEST but avoids 64 bit division */
> static u64 div_round64(u64 dividend, u32 divisor)
> @@ -192,6 +191,80 @@ static u64 div_round64(u64 dividend, u32 divisor)
> return div_u64(dividend + (divisor / 2), divisor);
> }
>
> +/**
> + * menu_update - attempts to guess what happened after entry
> + * @drv: cpuidle driver containing state data
> + * @dev: the CPU
> + */
> +static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev)
> +{
> + struct menu_device *data = &__get_cpu_var(menu_devices);
> + int last_idx = data->last_state_idx;
> + struct cpuidle_state *target = &drv->states[last_idx];
> + unsigned int measured_us;
> + unsigned int new_factor;
> +
> + /*
> + * Try to figure out how much time passed between entry to low
> + * power state and occurrence of the wakeup event.
> + *
> + * If the entered idle state didn't support residency measurements,
> + * we are basically lost in the dark how much time passed.
> + * As a compromise, assume we slept for the whole expected time.
> + *
> + * Any measured amount of time will include the exit latency.
> + * Since we are interested in when the wakeup begun, not when it
> + * was completed, we must subtract the exit latency. However, if
> + * the measured amount of time is less than the exit latency,
> + * assume the state was never reached and the exit latency is 0.
> + */
> + if (unlikely(!(target->flags & CPUIDLE_FLAG_TIME_VALID))) {
> + /* Use timer value as is */
> + measured_us = data->next_timer_us;
> +
> + } else {
> + /* Use measured value */
> + measured_us = cpuidle_get_last_residency(dev);
> +
> + /* Deduct exit latency */
> + if (measured_us > target->exit_latency)
> + measured_us -= target->exit_latency;
> +
> + /* Make sure our coefficients do not exceed unity */
> + if (measured_us > data->next_timer_us)
> + measured_us = data->next_timer_us;
> + }
> +
> + /* Update our correction ratio */
> + new_factor = data->correction_factor[data->bucket];
> + new_factor -= new_factor / DECAY;
> +
> + if (data->next_timer_us > 0 && measured_us < MAX_INTERESTING)
> + new_factor += RESOLUTION * measured_us / data->next_timer_us;
> + else
> + /*
> + * we were idle so long that we count it as a perfect
> + * prediction
> + */
> + new_factor += RESOLUTION;
> +
> + /*
> + * We don't want 0 as factor; we always want at least
> + * a tiny bit of estimated time. Fortunately, due to rounding,
> + * new_factor will stay nonzero regardless of measured_us values
> + * and the compiler can eliminate this test as long as DECAY > 1.
> + */
> + if (DECAY == 1 && unlikely(new_factor == 0))
> + new_factor = 1;
> +
> + data->correction_factor[data->bucket] = new_factor;
> +
> + /* update the repeating-pattern data */
> + data->intervals[data->interval_ptr++] = measured_us;
> + if (data->interval_ptr >= INTERVALS)
> + data->interval_ptr = 0;
> +}
> +
> /*
> * Try detecting repeating patterns by keeping track of the last 8
> * intervals, and checking if the standard deviation of that set
> @@ -378,80 +451,6 @@ static void menu_reflect(struct cpuidle_device *dev, int index)
> }
>
> /**
> - * menu_update - attempts to guess what happened after entry
> - * @drv: cpuidle driver containing state data
> - * @dev: the CPU
> - */
> -static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev)
> -{
> - struct menu_device *data = &__get_cpu_var(menu_devices);
> - int last_idx = data->last_state_idx;
> - struct cpuidle_state *target = &drv->states[last_idx];
> - unsigned int measured_us;
> - unsigned int new_factor;
> -
> - /*
> - * Try to figure out how much time passed between entry to low
> - * power state and occurrence of the wakeup event.
> - *
> - * If the entered idle state didn't support residency measurements,
> - * we are basically lost in the dark how much time passed.
> - * As a compromise, assume we slept for the whole expected time.
> - *
> - * Any measured amount of time will include the exit latency.
> - * Since we are interested in when the wakeup begun, not when it
> - * was completed, we must subtract the exit latency. However, if
> - * the measured amount of time is less than the exit latency,
> - * assume the state was never reached and the exit latency is 0.
> - */
> - if (unlikely(!(target->flags & CPUIDLE_FLAG_TIME_VALID))) {
> - /* Use timer value as is */
> - measured_us = data->next_timer_us;
> -
> - } else {
> - /* Use measured value */
> - measured_us = cpuidle_get_last_residency(dev);
> -
> - /* Deduct exit latency */
> - if (measured_us > target->exit_latency)
> - measured_us -= target->exit_latency;
> -
> - /* Make sure our coefficients do not exceed unity */
> - if (measured_us > data->next_timer_us)
> - measured_us = data->next_timer_us;
> - }
> -
> - /* Update our correction ratio */
> - new_factor = data->correction_factor[data->bucket];
> - new_factor -= new_factor / DECAY;
> -
> - if (data->next_timer_us > 0 && measured_us < MAX_INTERESTING)
> - new_factor += RESOLUTION * measured_us / data->next_timer_us;
> - else
> - /*
> - * we were idle so long that we count it as a perfect
> - * prediction
> - */
> - new_factor += RESOLUTION;
> -
> - /*
> - * We don't want 0 as factor; we always want at least
> - * a tiny bit of estimated time. Fortunately, due to rounding,
> - * new_factor will stay nonzero regardless of measured_us values
> - * and the compiler can eliminate this test as long as DECAY > 1.
> - */
> - if (DECAY == 1 && unlikely(new_factor == 0))
> - new_factor = 1;
> -
> - data->correction_factor[data->bucket] = new_factor;
> -
> - /* update the repeating-pattern data */
> - data->intervals[data->interval_ptr++] = measured_us;
> - if (data->interval_ptr >= INTERVALS)
> - data->interval_ptr = 0;
> -}
> -
> -/**
> * menu_enable_device - scans a CPU's states and does setup
> * @drv: cpuidle driver
> * @dev: the CPU
> --
> 1.9.1
>
>
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