Re: [PATCH v3]PM/Sleep: Timer quiesce in freeze state
From: Li, Aubrey
Date: Tue Jan 13 2015 - 19:24:16 EST
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@xxxxxxxxxxxxx>
> Signed-off-by: Aubrey Li <aubrey.li@xxxxxxxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> Cc: Len Brown <len.brown@xxxxxxxxx>
> Cc: Alan Cox <alan@xxxxxxxxxxxxxxx>
> ---
> 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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