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Date: Thu, 01 May 2014 00:47:25 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Daniel Lezcano <daniel.lezcano@...aro.org>
Cc: peterz@...radead.org, mingo@...e.hu, amit.kucheria@...aro.org,
linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 1/2] sched: idle: Encapsulate the code to compile it out
On Wednesday, April 30, 2014 02:01:02 PM Daniel Lezcano wrote:
> Encapsulate the large portion of cpuidle_idle_call inside another
> function so when CONFIG_CPU_IDLE=n, the code will be compiled out.
> Also that is benefitial for the clarity of the code as it removes
> a nested indentation level.
>
> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
Well, this conflicts with
https://patchwork.kernel.org/patch/4071541/
which you haven't commented on and I still want cpuidle_select() to be able to
return negative values because of
https://patchwork.kernel.org/patch/4089631/
(and I have one more patch on top of these two that requires this).
Any ideas how to resolve that?
> ---
> kernel/sched/idle.c | 161 +++++++++++++++++++++++++++------------------------
> 1 file changed, 86 insertions(+), 75 deletions(-)
>
> diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
> index b8cd302..f2f4bc9 100644
> --- a/kernel/sched/idle.c
> +++ b/kernel/sched/idle.c
> @@ -63,6 +63,90 @@ void __weak arch_cpu_idle(void)
> local_irq_enable();
> }
>
> +#ifdef CONFIG_CPU_IDLE
> +static int __cpuidle_idle_call(void)
> +{
> + struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
> + struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
> + int next_state, entered_state, ret;
> + bool broadcast;
> +
> + /*
> + * Check if the cpuidle framework is ready, otherwise fallback
> + * to the default arch specific idle method
> + */
> + ret = cpuidle_enabled(drv, dev);
> + if (ret)
> + return ret;
> +
> + /*
> + * Ask the governor to choose an idle state it thinks
> + * it is convenient to go to. There is *always* a
> + * convenient idle state
> + */
> + next_state = cpuidle_select(drv, dev);
> +
> + /*
> + * The idle task must be scheduled, it is pointless to
> + * go to idle, just update no idle residency and get
> + * out of this function
> + */
> + if (current_clr_polling_and_test()) {
> + dev->last_residency = 0;
> + entered_state = next_state;
> + local_irq_enable();
> + } else {
> + broadcast = !!(drv->states[next_state].flags &
> + CPUIDLE_FLAG_TIMER_STOP);
> +
> + if (broadcast)
> + /*
> + * Tell the time framework to switch to a
> + * broadcast timer because our local timer
> + * will be shutdown. If a local timer is used
> + * from another cpu as a broadcast timer, this
> + * call may fail if it is not available
> + */
> + ret = clockevents_notify(
> + CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
> + &dev->cpu);
> +
> + if (!ret) {
> + trace_cpu_idle_rcuidle(next_state, dev->cpu);
> +
> + /*
> + * Enter the idle state previously returned by
> + * the governor decision. This function will
> + * block until an interrupt occurs and will
> + * take care of re-enabling the local
> + * interrupts
> + */
> + entered_state = cpuidle_enter(drv, dev, next_state);
> +
> + trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
> +
> + if (broadcast)
> + clockevents_notify(
> + CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
> + &dev->cpu);
> +
> + /*
> + * Give the governor an opportunity to reflect
> + * on the outcome
> + */
> + cpuidle_reflect(dev, entered_state);
> + }
> + }
> +
> + return 0;
> +}
> +#else
> +static int inline __cpuidle_idle_call(void)
> +{
> + return -ENOSYS;
> +}
> +#endif
> +
> /**
> * cpuidle_idle_call - the main idle function
> *
> @@ -70,10 +154,7 @@ void __weak arch_cpu_idle(void)
> */
> static void cpuidle_idle_call(void)
> {
> - struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
> - struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
> - int next_state, entered_state, ret;
> - bool broadcast;
> + int ret;
>
> /*
> * Check if the idle task must be rescheduled. If it is the
> @@ -100,80 +181,10 @@ static void cpuidle_idle_call(void)
> rcu_idle_enter();
>
> /*
> - * Check if the cpuidle framework is ready, otherwise fallback
> - * to the default arch specific idle method
> - */
> - ret = cpuidle_enabled(drv, dev);
> -
> - if (!ret) {
> - /*
> - * Ask the governor to choose an idle state it thinks
> - * it is convenient to go to. There is *always* a
> - * convenient idle state
> - */
> - next_state = cpuidle_select(drv, dev);
> -
> - /*
> - * The idle task must be scheduled, it is pointless to
> - * go to idle, just update no idle residency and get
> - * out of this function
> - */
> - if (current_clr_polling_and_test()) {
> - dev->last_residency = 0;
> - entered_state = next_state;
> - local_irq_enable();
> - } else {
> - broadcast = !!(drv->states[next_state].flags &
> - CPUIDLE_FLAG_TIMER_STOP);
> -
> - if (broadcast)
> - /*
> - * Tell the time framework to switch
> - * to a broadcast timer because our
> - * local timer will be shutdown. If a
> - * local timer is used from another
> - * cpu as a broadcast timer, this call
> - * may fail if it is not available
> - */
> - ret = clockevents_notify(
> - CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
> - &dev->cpu);
> -
> - if (!ret) {
> - trace_cpu_idle_rcuidle(next_state, dev->cpu);
> -
> - /*
> - * Enter the idle state previously
> - * returned by the governor
> - * decision. This function will block
> - * until an interrupt occurs and will
> - * take care of re-enabling the local
> - * interrupts
> - */
> - entered_state = cpuidle_enter(drv, dev,
> - next_state);
> -
> - trace_cpu_idle_rcuidle(PWR_EVENT_EXIT,
> - dev->cpu);
> -
> - if (broadcast)
> - clockevents_notify(
> - CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
> - &dev->cpu);
> -
> - /*
> - * Give the governor an opportunity to reflect on the
> - * outcome
> - */
> - cpuidle_reflect(dev, entered_state);
> - }
> - }
> - }
> -
> - /*
> * We can't use the cpuidle framework, let's use the default
> * idle routine
> */
> + ret = __cpuidle_idle_call();
> if (ret)
> arch_cpu_idle();
>
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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