Re: [PATCH 3/6] cpuidle: menu: Get rid of first_idx from menu_select()

Daniel Lezcano
2018-10-04T14:51:17Z

On Tue, Oct 02, 2018 at 11:44:06PM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Rearrange the code in menu_select() so that the loop over idle states
> always starts from 0 and get rid of the first_idx variable.
>
> While at it, add two empty lines to separate conditional statements
> one another.
>
> No intentional behavior changes.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---

This code is becoming a bit complex to follow :/

May be I missed something, but it is not possible to enter the condition without
idx != 0, no ? (I meant the condition if ((drv->states[idx].flags &
FLAG_POLLING))

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

> drivers/cpuidle/governors/menu.c | 32 ++++++++++++++------------------
> 1 file changed, 14 insertions(+), 18 deletions(-)
>
> Index: linux-pm/drivers/cpuidle/governors/menu.c
> ===================================================================
> --- linux-pm.orig/drivers/cpuidle/governors/menu.c
> +++ linux-pm/drivers/cpuidle/governors/menu.c
> @@ -285,7 +285,6 @@ static int menu_select(struct cpuidle_dr
> struct menu_device *data = this_cpu_ptr(&menu_devices);
> int latency_req = cpuidle_governor_latency_req(dev->cpu);
> int i;
> - int first_idx;
> int idx;
> unsigned int interactivity_req;
> unsigned int expected_interval;
> @@ -348,36 +347,33 @@ static int menu_select(struct cpuidle_dr
> latency_req = interactivity_req;
> }
>
> - first_idx = 0;
> - if (drv->states[0].flags & CPUIDLE_FLAG_POLLING) {
> - struct cpuidle_state *s = &drv->states[1];
> - unsigned int polling_threshold;
> -
> - /*
> - * Default to a physical idle state, not to busy polling, unless
> - * a timer is going to trigger really really soon.
> - */
> - polling_threshold = max_t(unsigned int, 20, s->target_residency);
> - if (data->next_timer_us > polling_threshold &&
> - latency_req > s->exit_latency && !s->disabled &&
> - !dev->states_usage[1].disable)
> - first_idx = 1;
> - }
> -
> /*
> * Find the idle state with the lowest power while satisfying
> * our constraints.
> */
> idx = -1;
> - for (i = first_idx; i < drv->state_count; i++) {
> + for (i = 0; i < drv->state_count; i++) {
> struct cpuidle_state *s = &drv->states[i];
> struct cpuidle_state_usage *su = &dev->states_usage[i];
>
> if (s->disabled || su->disable)
> continue;
> +
> if (idx == -1)
> idx = i; /* first enabled state */
> +
> if (s->target_residency > predicted_us) {
> + /*
> + * Use a physical idle state, not busy polling, unless
> + * a timer is going to trigger really really soon.
> + */
> + if ((drv->states[idx].flags & CPUIDLE_FLAG_POLLING) &&
> + i == idx + 1 && latency_req > s->exit_latency &&
> + data->next_timer_us > max_t(unsigned int, 20,
> + s->target_residency)) {
> + idx = i;
> + break;
> + }
> if (predicted_us < TICK_USEC)
> break;
>
>

--

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