Hi Daniel,
On 12/14/2012 02:57 PM, Daniel Lezcano wrote:
> As the power is backward sorted in the states array and we are looking for
> the state consuming the little power as possible, instead of looking from
> the beginning of the array, we look from the end. That should save us some
> iterations in the loop each time we select a state at idle time.
>
> Signed-off-by: Daniel Lezcano <daniel.lezc...@linaro.org>
> ---
> drivers/cpuidle/governors/menu.c | 12 ++++++------
> 1 files changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/cpuidle/governors/menu.c
> b/drivers/cpuidle/governors/menu.c
> index fe343a0..05b8998 100644
> --- a/drivers/cpuidle/governors/menu.c
> +++ b/drivers/cpuidle/governors/menu.c
> @@ -367,24 +367,24 @@ static int menu_select(struct cpuidle_driver *drv,
> struct cpuidle_device *dev)
> * Find the idle state with the lowest power while satisfying
> * our constraints.
> */
> - for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
> + for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--) {
> struct cpuidle_state *s = &drv->states[i];
> struct cpuidle_state_usage *su = &dev->states_usage[i];
>
> if (s->disabled || su->disable)
> continue;
> - if (s->target_residency > data->predicted_us) {
> - low_predicted = 1;
> - continue;
> - }
> if (s->exit_latency > latency_req)
> continue;
> + if (s->target_residency > data->predicted_us)
> + continue;
> if (s->exit_latency * multiplier > data->predicted_us)
> continue;
>
> + low_predicted = i - CPUIDLE_DRIVER_STATE_START;
You are altering the semantics of low_predicted, which is supposed to be
non-zero when the deepest C-state has not been chosen because its target
residency is more than the predicted residency.
It seems to me that the if block where target_residency is compared with
the predicted residency should be left as is.
> data->last_state_idx = i;
> data->exit_us = s->exit_latency;
> - }
> + break;
> + }
>
> /* not deepest C-state chosen for low predicted residency */
> if (low_predicted) {
--
Francesco
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