Date:	Wed, 14 Jan 2015 08:24:04 +0800
From:	"Li, Aubrey" <aubrey.li@...ux.intel.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"Brown, Len" <len.brown@...el.com>,
	"alan@...ux.intel.com" <alan@...ux.intel.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v3]PM/Sleep: Timer quiesce in freeze state

Happy New Year, can you please take a look at this patch now?

Thanks,
-Aubrey

On 2014/12/9 11:01, Li, Aubrey wrote:
> The patch is based on v3.18.
> 
> Freeze is a general power saving state that processes are frozen, devices
> are suspended and CPUs are in idle state. However, when the system enters
> freeze state, there are a few timers keep ticking and hence consumes more
> power unnecessarily. The observed timer events in freeze state are:
> - tick_sched_timer
> - watchdog lockup detector
> - realtime scheduler period timer
> 
> The system power consumption in freeze state will be reduced significantly
> if we quiesce these timers.
> 
> The patch is tested on:
> - Sandybrdige-EP system, both RTC alarm and power button are able to wake
>   the system up from freeze state.
> - HP laptop EliteBook 8460p, both RTC alarm and power button are able to
>   wake the system up from freeze state.
> - Baytrail-T(ASUS_T100) platform, power button is able to wake the system
>   up from freeze state.
> 
> Suggested-by: Thomas Gleixner <tglx@...utronix.de>
> Signed-off-by: Aubrey Li <aubrey.li@...ux.intel.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> Cc: Len Brown <len.brown@...el.com>
> Cc: Alan Cox <alan@...ux.intel.com>
> ---
>  drivers/cpuidle/cpuidle.c   | 13 ++++++++
>  include/linux/clockchips.h  |  4 +++
>  include/linux/suspend.h     |  4 +++
>  include/linux/timekeeping.h |  2 ++
>  kernel/power/suspend.c      | 50 ++++++++++++++++++++++++++---
>  kernel/sched/idle.c         | 45 ++++++++++++++++++++++++++
>  kernel/softirq.c            |  5 +--
>  kernel/time/clockevents.c   | 13 ++++++++
>  kernel/time/tick-common.c   | 53 +++++++++++++++++++++++++++++++
>  kernel/time/tick-internal.h |  3 ++
>  kernel/time/timekeeping.c   | 77 +++++++++++++++++++++++++++++++++------------
>  11 files changed, 243 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
> index 125150d..b9a3ada 100644
> --- a/drivers/cpuidle/cpuidle.c
> +++ b/drivers/cpuidle/cpuidle.c
> @@ -20,6 +20,7 @@
>  #include <linux/hrtimer.h>
>  #include <linux/module.h>
>  #include <trace/events/power.h>
> +#include <linux/suspend.h>
>  
>  #include "cpuidle.h"
>  
> @@ -119,6 +120,18 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
>  	ktime_t time_start, time_end;
>  	s64 diff;
>  
> +	/*
> +	 * under the freeze scenario, the timekeeping is suspended
> +	 * as well as the clock source device, so we bypass the idle
> +	 * counter update in freeze idle
> +	 */
> +	if (in_freeze()) {
> +		entered_state = target_state->enter(dev, drv, index);
> +		if (!cpuidle_state_is_coupled(dev, drv, entered_state))
> +			local_irq_enable();
> +		return entered_state;
> +	}
> +
>  	trace_cpu_idle_rcuidle(index, dev->cpu);
>  	time_start = ktime_get();
>  
> diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h
> index 2e4cb67..d118e0b 100644
> --- a/include/linux/clockchips.h
> +++ b/include/linux/clockchips.h
> @@ -18,6 +18,9 @@ enum clock_event_nofitiers {
>  	CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
>  	CLOCK_EVT_NOTIFY_SUSPEND,
>  	CLOCK_EVT_NOTIFY_RESUME,
> +	CLOCK_EVT_NOTIFY_FREEZE_PREPARE,
> +	CLOCK_EVT_NOTIFY_FREEZE,
> +	CLOCK_EVT_NOTIFY_UNFREEZE,
>  	CLOCK_EVT_NOTIFY_CPU_DYING,
>  	CLOCK_EVT_NOTIFY_CPU_DEAD,
>  };
> @@ -95,6 +98,7 @@ enum clock_event_mode {
>   */
>  struct clock_event_device {
>  	void			(*event_handler)(struct clock_event_device *);
> +	void			(*real_handler)(struct clock_event_device *);
>  	int			(*set_next_event)(unsigned long evt,
>  						  struct clock_event_device *);
>  	int			(*set_next_ktime)(ktime_t expires,
> diff --git a/include/linux/suspend.h b/include/linux/suspend.h
> index 3388c1b..86a651c 100644
> --- a/include/linux/suspend.h
> +++ b/include/linux/suspend.h
> @@ -203,6 +203,8 @@ extern void suspend_set_ops(const struct platform_suspend_ops *ops);
>  extern int suspend_valid_only_mem(suspend_state_t state);
>  extern void freeze_set_ops(const struct platform_freeze_ops *ops);
>  extern void freeze_wake(void);
> +extern bool in_freeze(void);
> +extern bool idle_should_freeze(void);
>  
>  /**
>   * arch_suspend_disable_irqs - disable IRQs for suspend
> @@ -230,6 +232,8 @@ static inline void suspend_set_ops(const struct platform_suspend_ops *ops) {}
>  static inline int pm_suspend(suspend_state_t state) { return -ENOSYS; }
>  static inline void freeze_set_ops(const struct platform_freeze_ops *ops) {}
>  static inline void freeze_wake(void) {}
> +static inline bool in_freeze(void) { return false; }
> +static inline bool idle_should_freeze(void) { return false; }
>  #endif /* !CONFIG_SUSPEND */
>  
>  /* struct pbe is used for creating lists of pages that should be restored
> diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
> index 1caa6b0..07957a9 100644
> --- a/include/linux/timekeeping.h
> +++ b/include/linux/timekeeping.h
> @@ -5,6 +5,8 @@
>  
>  void timekeeping_init(void);
>  extern int timekeeping_suspended;
> +extern void timekeeping_freeze(void);
> +extern void timekeeping_unfreeze(void);
>  
>  /*
>   * Get and set timeofday
> diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
> index c347e3c..6467fb8 100644
> --- a/kernel/power/suspend.c
> +++ b/kernel/power/suspend.c
> @@ -28,6 +28,7 @@
>  #include <linux/ftrace.h>
>  #include <trace/events/power.h>
>  #include <linux/compiler.h>
> +#include <linux/clockchips.h>
>  
>  #include "power.h"
>  
> @@ -37,7 +38,15 @@ const char *pm_states[PM_SUSPEND_MAX];
>  static const struct platform_suspend_ops *suspend_ops;
>  static const struct platform_freeze_ops *freeze_ops;
>  static DECLARE_WAIT_QUEUE_HEAD(suspend_freeze_wait_head);
> -static bool suspend_freeze_wake;
> +
> +/* freeze state machine */
> +enum freeze_state {
> +	FREEZE_STATE_NONE,      /* not in freeze */
> +	FREEZE_STATE_ENTER,     /* enter freeze */
> +	FREEZE_STATE_WAKE,      /* in freeze wakeup context */
> +};
> +
> +static enum freeze_state suspend_freeze_state;
>  
>  void freeze_set_ops(const struct platform_freeze_ops *ops)
>  {
> @@ -46,23 +55,56 @@ void freeze_set_ops(const struct platform_freeze_ops *ops)
>  	unlock_system_sleep();
>  }
>  
> +bool in_freeze(void)
> +{
> +	return (suspend_freeze_state > FREEZE_STATE_NONE);
> +}
> +EXPORT_SYMBOL_GPL(in_freeze);
> +
> +bool idle_should_freeze(void)
> +{
> +	return (suspend_freeze_state == FREEZE_STATE_ENTER);
> +}
> +EXPORT_SYMBOL_GPL(idle_should_freeze);
> +
>  static void freeze_begin(void)
>  {
> -	suspend_freeze_wake = false;
> +	suspend_freeze_state = FREEZE_STATE_NONE;
>  }
>  
>  static void freeze_enter(void)
>  {
> +	suspend_freeze_state = FREEZE_STATE_ENTER;
> +	get_online_cpus();
>  	cpuidle_use_deepest_state(true);
>  	cpuidle_resume();
> -	wait_event(suspend_freeze_wait_head, suspend_freeze_wake);
> +	clockevents_notify(CLOCK_EVT_NOTIFY_FREEZE_PREPARE, NULL);
> +	/*
> +	 * push all the CPUs into freeze idle loop
> +	 */
> +	wake_up_all_idle_cpus();
> +	printk(KERN_INFO "PM: suspend to idle\n");
> +	/*
> +	 * put the current CPU into wait queue so that this CPU
> +	 * is able to enter freeze idle loop as well
> +	 */
> +	wait_event(suspend_freeze_wait_head,
> +		(suspend_freeze_state == FREEZE_STATE_WAKE));
> +	printk(KERN_INFO "PM: resume from freeze\n");
>  	cpuidle_pause();
>  	cpuidle_use_deepest_state(false);
> +	put_online_cpus();
> +	suspend_freeze_state = FREEZE_STATE_NONE;
>  }
>  
>  void freeze_wake(void)
>  {
> -	suspend_freeze_wake = true;
> +	if (!in_freeze())
> +		return;
> +	/*
> +	 * wake freeze task up
> +	 */
> +	suspend_freeze_state = FREEZE_STATE_WAKE;
>  	wake_up(&suspend_freeze_wait_head);
>  }
>  EXPORT_SYMBOL_GPL(freeze_wake);
> diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
> index c47fce7..f28f8cb 100644
> --- a/kernel/sched/idle.c
> +++ b/kernel/sched/idle.c
> @@ -7,6 +7,7 @@
>  #include <linux/tick.h>
>  #include <linux/mm.h>
>  #include <linux/stackprotector.h>
> +#include <linux/suspend.h>
>  
>  #include <asm/tlb.h>
>  
> @@ -182,6 +183,45 @@ exit_idle:
>  }
>  
>  /*
> + * cpu idle freeze function
> + */
> +static void cpu_idle_freeze(void)
> +{
> +	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
> +	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
> +
> +	/*
> +	 * suspend tick, the last CPU suspend timekeeping
> +	 */
> +	clockevents_notify(CLOCK_EVT_NOTIFY_FREEZE, NULL);
> +	/*
> +	 * idle loop here if idle_should_freeze()
> +	 */
> +	while (idle_should_freeze()) {
> +		int next_state;
> +		/*
> +		 * interrupt must be disabled before cpu enters idle
> +		 */
> +		local_irq_disable();
> +
> +		next_state = cpuidle_select(drv, dev);
> +		if (next_state < 0) {
> +			arch_cpu_idle();
> +			continue;
> +		}
> +		/*
> +		 * cpuidle_enter will return with interrupt enabled
> +		 */
> +		cpuidle_enter(drv, dev, next_state);
> +	}
> +
> +	/*
> +	 * resume tick, the first wakeup CPU resume timekeeping
> +	 */
> +	clockevents_notify(CLOCK_EVT_NOTIFY_UNFREEZE, NULL);
> +}
> +
> +/*
>   * Generic idle loop implementation
>   *
>   * Called with polling cleared.
> @@ -208,6 +248,11 @@ static void cpu_idle_loop(void)
>  			if (cpu_is_offline(smp_processor_id()))
>  				arch_cpu_idle_dead();
>  
> +			if (idle_should_freeze()) {
> +				cpu_idle_freeze();
> +				continue;
> +			}
> +
>  			local_irq_disable();
>  			arch_cpu_idle_enter();
>  
> diff --git a/kernel/softirq.c b/kernel/softirq.c
> index 0699add..a231bf6 100644
> --- a/kernel/softirq.c
> +++ b/kernel/softirq.c
> @@ -26,6 +26,7 @@
>  #include <linux/smpboot.h>
>  #include <linux/tick.h>
>  #include <linux/irq.h>
> +#include <linux/suspend.h>
>  
>  #define CREATE_TRACE_POINTS
>  #include <trace/events/irq.h>
> @@ -321,7 +322,7 @@ asmlinkage __visible void do_softirq(void)
>  void irq_enter(void)
>  {
>  	rcu_irq_enter();
> -	if (is_idle_task(current) && !in_interrupt()) {
> +	if (is_idle_task(current) && !in_interrupt() && !in_freeze()) {
>  		/*
>  		 * Prevent raise_softirq from needlessly waking up ksoftirqd
>  		 * here, as softirq will be serviced on return from interrupt.
> @@ -364,7 +365,7 @@ static inline void tick_irq_exit(void)
>  
>  	/* Make sure that timer wheel updates are propagated */
>  	if ((idle_cpu(cpu) && !need_resched()) || tick_nohz_full_cpu(cpu)) {
> -		if (!in_interrupt())
> +		if (!in_interrupt() && !in_freeze())
>  			tick_nohz_irq_exit();
>  	}
>  #endif
> diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
> index 5544990..6d9a4a3 100644
> --- a/kernel/time/clockevents.c
> +++ b/kernel/time/clockevents.c
> @@ -17,6 +17,7 @@
>  #include <linux/module.h>
>  #include <linux/smp.h>
>  #include <linux/device.h>
> +#include <linux/suspend.h>
>  
>  #include "tick-internal.h"
>  
> @@ -579,6 +580,18 @@ int clockevents_notify(unsigned long reason, void *arg)
>  		tick_resume();
>  		break;
>  
> +	case CLOCK_EVT_NOTIFY_FREEZE_PREPARE:
> +		tick_freeze_prepare();
> +		break;
> +
> +	case CLOCK_EVT_NOTIFY_FREEZE:
> +		tick_freeze();
> +		break;
> +
> +	case CLOCK_EVT_NOTIFY_UNFREEZE:
> +		tick_unfreeze();
> +		break;
> +
>  	case CLOCK_EVT_NOTIFY_CPU_DEAD:
>  		tick_shutdown_broadcast_oneshot(arg);
>  		tick_shutdown_broadcast(arg);
> diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
> index 7efeedf..0bbc886 100644
> --- a/kernel/time/tick-common.c
> +++ b/kernel/time/tick-common.c
> @@ -19,6 +19,7 @@
>  #include <linux/profile.h>
>  #include <linux/sched.h>
>  #include <linux/module.h>
> +#include <linux/suspend.h>
>  
>  #include <asm/irq_regs.h>
>  
> @@ -51,6 +52,16 @@ ktime_t tick_period;
>  int tick_do_timer_cpu __read_mostly = TICK_DO_TIMER_BOOT;
>  
>  /*
> + * Tick device is per CPU device, when we freeze the timekeeping stuff, we
> + * want to freeze the tick device on all of the online CPUs.
> + *
> + * tick_freeze_target_depth is a counter used for freezing tick device, the
> + * initial value of it is online CPU number. When it is counted down to ZERO,
> + * all of the tick devices are freezed.
> + */
> +static unsigned int tick_freeze_target_depth;
> +
> +/*
>   * Debugging: see timer_list.c
>   */
>  struct tick_device *tick_get_device(int cpu)
> @@ -375,15 +386,21 @@ void tick_shutdown(unsigned int *cpup)
>  void tick_suspend(void)
>  {
>  	struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
> +	struct clock_event_device *dev = td->evtdev;
>  
> +	dev->real_handler = dev->event_handler;
> +	dev->event_handler = clockevents_handle_noop;
>  	clockevents_shutdown(td->evtdev);
>  }
>  
>  void tick_resume(void)
>  {
>  	struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
> +	struct clock_event_device *dev = td->evtdev;
>  	int broadcast = tick_resume_broadcast();
>  
> +	dev->event_handler = dev->real_handler;
> +	dev->real_handler = NULL;
>  	clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_RESUME);
>  
>  	if (!broadcast) {
> @@ -394,6 +411,42 @@ void tick_resume(void)
>  	}
>  }
>  
> +void tick_freeze_prepare(void)
> +{
> +	tick_freeze_target_depth = num_online_cpus();
> +}
> +
> +void tick_freeze(void)
> +{
> +	/*
> +	 * This is serialized against a concurrent wakeup
> +	 * via clockevents_lock
> +	 */
> +	tick_freeze_target_depth--;
> +	tick_suspend();
> +
> +	/*
> +	 * the last tick_suspend CPU suspends timekeeping
> +	 */
> +	if (!tick_freeze_target_depth)
> +		timekeeping_freeze();
> +}
> +
> +void tick_unfreeze(void)
> +{
> +	/*
> +	 * the first wakeup CPU resumes timekeeping
> +	 */
> +	if (timekeeping_suspended) {
> +		timekeeping_unfreeze();
> +		touch_softlockup_watchdog();
> +		tick_resume();
> +		hrtimers_resume();
> +	} else {
> +		tick_resume();
> +	}
> +}
> +
>  /**
>   * tick_init - initialize the tick control
>   */
> diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
> index 366aeb4..8b5bab6 100644
> --- a/kernel/time/tick-internal.h
> +++ b/kernel/time/tick-internal.h
> @@ -27,6 +27,9 @@ extern void tick_handover_do_timer(int *cpup);
>  extern void tick_shutdown(unsigned int *cpup);
>  extern void tick_suspend(void);
>  extern void tick_resume(void);
> +extern void tick_freeze_prepare(void);
> +extern void tick_freeze(void);
> +extern void tick_unfreeze(void);
>  extern bool tick_check_replacement(struct clock_event_device *curdev,
>  				   struct clock_event_device *newdev);
>  extern void tick_install_replacement(struct clock_event_device *dev);
> diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
> index ec1791f..a11065f 100644
> --- a/kernel/time/timekeeping.c
> +++ b/kernel/time/timekeeping.c
> @@ -1107,14 +1107,7 @@ void timekeeping_inject_sleeptime(struct timespec *delta)
>  	clock_was_set();
>  }
>  
> -/**
> - * timekeeping_resume - Resumes the generic timekeeping subsystem.
> - *
> - * This is for the generic clocksource timekeeping.
> - * xtime/wall_to_monotonic/jiffies/etc are
> - * still managed by arch specific suspend/resume code.
> - */
> -static void timekeeping_resume(void)
> +static void timekeeping_resume_compensate_time(void)
>  {
>  	struct timekeeper *tk = &tk_core.timekeeper;
>  	struct clocksource *clock = tk->tkr.clock;
> @@ -1127,9 +1120,6 @@ static void timekeeping_resume(void)
>  	read_persistent_clock(&tmp);
>  	ts_new = timespec_to_timespec64(tmp);
>  
> -	clockevents_resume();
> -	clocksource_resume();
> -
>  	raw_spin_lock_irqsave(&timekeeper_lock, flags);
>  	write_seqcount_begin(&tk_core.seq);
>  
> @@ -1186,16 +1176,9 @@ static void timekeeping_resume(void)
>  	timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
>  	write_seqcount_end(&tk_core.seq);
>  	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
> -
> -	touch_softlockup_watchdog();
> -
> -	clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
> -
> -	/* Resume hrtimers */
> -	hrtimers_resume();
>  }
>  
> -static int timekeeping_suspend(void)
> +static void timekeeping_suspend_get_time(void)
>  {
>  	struct timekeeper *tk = &tk_core.timekeeper;
>  	unsigned long flags;
> @@ -1242,11 +1225,65 @@ static int timekeeping_suspend(void)
>  	timekeeping_update(tk, TK_MIRROR);
>  	write_seqcount_end(&tk_core.seq);
>  	raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
> +}
>  
> -	clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
> +/*
> + * The following operations:
> + *	clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
> + *	clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
> + * are moved out of
> + *	timekeeping_freeze() and timekeeping_unfreeze()
> + * and, replaced by
> + *	tick_suspend() and tick_resume()
> + * and, put into:
> + *	tick_freeze() and tick_unfreeze()
> + * so we avoid clockevents_lock multiple access
> + */
> +void timekeeping_freeze(void)
> +{
> +	/*
> +	 * clockevents_lock being held
> +	 */
> +	timekeeping_suspend_get_time();
>  	clocksource_suspend();
>  	clockevents_suspend();
> +}
>  
> +void timekeeping_unfreeze(void)
> +{
> +	/*
> +	 * clockevents_lock being held
> +	 */
> +	clockevents_resume();
> +	clocksource_resume();
> +	timekeeping_resume_compensate_time();
> +}
> +
> +/**
> + * timekeeping_resume - Resumes the generic timekeeping subsystem.
> + *
> + * This is for the generic clocksource timekeeping.
> + * xtime/wall_to_monotonic/jiffies/etc are
> + * still managed by arch specific suspend/resume code.
> + */
> +static void timekeeping_resume(void)
> +{
> +	clockevents_resume();
> +	clocksource_resume();
> +	timekeeping_resume_compensate_time();
> +
> +	touch_softlockup_watchdog();
> +	clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
> +	/* Resume hrtimers */
> +	hrtimers_resume();
> +}
> +
> +static int timekeeping_suspend(void)
> +{
> +	timekeeping_suspend_get_time();
> +	clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
> +	clocksource_suspend();
> +	clockevents_suspend();
>  	return 0;
>  }
>  
> 

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