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Message-ID: <alpine.LFD.2.11.1402111226370.17677@knanqh.ubzr>
Date: Tue, 11 Feb 2014 12:27:19 -0500 (EST)
From: Nicolas Pitre <nicolas.pitre@...aro.org>
To: Daniel Lezcano <daniel.lezcano@...aro.org>
cc: mingo@...nel.org, peterz@...radead.org, tglx@...utronix.de,
rjw@...ysocki.net, preeti@...ux.vnet.ibm.com,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/5] idle/cpuidle: Split cpuidle_idle_call main function
into smaller functions
On Tue, 11 Feb 2014, Daniel Lezcano wrote:
> In order to allow better integration between the cpuidle framework and the
> scheduler, reducing the distance between these two sub-components will
> facilitate this integration by moving part of the cpuidle code in the idle
> task file and, because idle.c is in the sched directory, we have access to
> the scheduler's private structures.
>
> This patch splits the cpuidle_idle_call main entry function into 3 calls
> to a newly added API:
> 1. select the idle state
> 2. enter the idle state
> 3. reflect the idle state
>
> The cpuidle_idle_call calls these three functions to implement the main
> idle entry function.
>
> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
Acked-by: Nicolas Pitre <nico@...aro.org>
> ---
> drivers/cpuidle/cpuidle.c | 102 ++++++++++++++++++++++++++++++++-------------
> include/linux/cpuidle.h | 14 +++++++
> 2 files changed, 87 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
> index a55e68f..172ab6a 100644
> --- a/drivers/cpuidle/cpuidle.c
> +++ b/drivers/cpuidle/cpuidle.c
> @@ -108,6 +108,71 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
> }
>
> /**
> + * cpuidle_select - ask the cpuidle framework to choose an idle state
> + *
> + * @drv: the cpuidle driver
> + * @dev: the cpuidle device
> + *
> + * Returns the index of the idle state. On error it returns:
> + * -NODEV : the cpuidle framework is not available
> + * -EBUSY : the cpuidle framework is not initialized
> + */
> +int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
> +{
> + if (off || !initialized)
> + return -ENODEV;
> +
> + if (!drv || !dev || !dev->enabled)
> + return -EBUSY;
> +
> + return cpuidle_curr_governor->select(drv, dev);
> +}
> +
> +/**
> + * cpuidle_enter - enter into the specified idle state
> + *
> + * @drv: the cpuidle driver tied with the cpu
> + * @dev: the cpuidle device
> + * @index: the index in the idle state table
> + *
> + * Returns the index in the idle state, < 0 in case of error.
> + * The error code depends on the backend driver
> + */
> +int cpuidle_enter(struct cpuidle_driver *drv, struct cpuidle_device *dev,
> + int index)
> +{
> + int entered_state;
> + bool broadcast = !!(drv->states[index].flags & CPUIDLE_FLAG_TIMER_STOP);
> +
> + if (broadcast)
> + clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu);
> +
> + if (cpuidle_state_is_coupled(dev, drv, index))
> + entered_state = cpuidle_enter_state_coupled(dev, drv, index);
> + else
> + entered_state = cpuidle_enter_state(dev, drv, index);
> +
> + if (broadcast)
> + clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu);
> +
> + return entered_state;
> +}
> +
> +/**
> + * cpuidle_reflect - tell the underlying governor what was the state
> + * we were in
> + *
> + * @dev : the cpuidle device
> + * @index: the index in the idle state table
> + *
> + */
> +void cpuidle_reflect(struct cpuidle_device *dev, int index)
> +{
> + if (cpuidle_curr_governor->reflect)
> + cpuidle_curr_governor->reflect(dev, index);
> +}
> +
> +/**
> * cpuidle_idle_call - the main idle loop
> *
> * NOTE: no locks or semaphores should be used here
> @@ -116,51 +181,30 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
> int cpuidle_idle_call(void)
> {
> struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
> - struct cpuidle_driver *drv;
> + struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
> int next_state, entered_state;
> - bool broadcast;
> -
> - if (off || !initialized)
> - return -ENODEV;
> -
> - /* check if the device is ready */
> - if (!dev || !dev->enabled)
> - return -EBUSY;
> -
> - drv = cpuidle_get_cpu_driver(dev);
>
> /* ask the governor for the next state */
> - next_state = cpuidle_curr_governor->select(drv, dev);
> + next_state = cpuidle_select(drv, dev);
> + if (next_state < 0)
> + return next_state;
> +
> if (need_resched()) {
> dev->last_residency = 0;
> /* give the governor an opportunity to reflect on the outcome */
> - if (cpuidle_curr_governor->reflect)
> - cpuidle_curr_governor->reflect(dev, next_state);
> + cpuidle_reflect(dev, next_state);
> local_irq_enable();
> return 0;
> }
>
> trace_cpu_idle_rcuidle(next_state, dev->cpu);
>
> - broadcast = !!(drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP);
> -
> - if (broadcast)
> - clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu);
> -
> - if (cpuidle_state_is_coupled(dev, drv, next_state))
> - entered_state = cpuidle_enter_state_coupled(dev, drv,
> - next_state);
> - else
> - entered_state = cpuidle_enter_state(dev, drv, next_state);
> -
> - if (broadcast)
> - clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu);
> + entered_state = cpuidle_enter(drv, dev, next_state);
>
> trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
>
> /* give the governor an opportunity to reflect on the outcome */
> - if (cpuidle_curr_governor->reflect)
> - cpuidle_curr_governor->reflect(dev, entered_state);
> + cpuidle_reflect(dev, entered_state);
>
> return 0;
> }
> diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
> index 50fcbb0..bf06f37 100644
> --- a/include/linux/cpuidle.h
> +++ b/include/linux/cpuidle.h
> @@ -119,6 +119,13 @@ struct cpuidle_driver {
>
> #ifdef CONFIG_CPU_IDLE
> extern void disable_cpuidle(void);
> +
> +extern int cpuidle_select(struct cpuidle_driver *drv,
> + struct cpuidle_device *dev);
> +extern int cpuidle_enter(struct cpuidle_driver *drv,
> + struct cpuidle_device *dev, int index);
> +extern void cpuidle_reflect(struct cpuidle_device *dev, int index);
> +
> extern int cpuidle_idle_call(void);
> extern int cpuidle_register_driver(struct cpuidle_driver *drv);
> extern struct cpuidle_driver *cpuidle_get_driver(void);
> @@ -141,6 +148,13 @@ extern int cpuidle_play_dead(void);
> extern struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev);
> #else
> static inline void disable_cpuidle(void) { }
> +static inline int cpuidle_select(struct cpuidle_driver *drv,
> + struct cpuidle_device *dev)
> +{return -ENODEV; }
> +static inline int cpuidle_enter(struct cpuidle_driver *drv,
> + struct cpuidle_device *dev, int index)
> +{return -ENODEV; }
> +static inline void cpuidle_reflect(struct cpuidle_device *dev, int index) { }
> static inline int cpuidle_idle_call(void) { return -ENODEV; }
> static inline int cpuidle_register_driver(struct cpuidle_driver *drv)
> {return -ENODEV; }
> --
> 1.7.9.5
>
--
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