[PATCH] hrtimers: add high resolution timer support
Implement high resolution timers on top of the hrtimers infrastructure and the clockevents / tick-management framework. This provides accurate timers for all hrtimer subsystem users. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: john stultz <johnstul@us.ibm.com> Cc: Roman Zippel <zippel@linux-m68k.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Thomas Gleixner
Linus Torvalds
Родитель
d40891e75f
Коммит
54cdfdb47f
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@ -609,6 +609,10 @@ and is between 256 and 4096 characters. It is defined in the file
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highmem otherwise. This also works to reduce highmem
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size on bigger boxes.
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highres= [KNL] Enable/disable high resolution timer mode.
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Valid parameters: "on", "off"
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Default: "on"
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hisax= [HW,ISDN]
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See Documentation/isdn/README.HiSax.
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@ -41,16 +41,35 @@ enum hrtimer_restart {
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};
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/*
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* Bit values to track state of the timer
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* hrtimer callback modes:
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*
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* HRTIMER_CB_SOFTIRQ: Callback must run in softirq context
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* HRTIMER_CB_IRQSAFE: Callback may run in hardirq context
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* HRTIMER_CB_IRQSAFE_NO_RESTART: Callback may run in hardirq context and
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* does not restart the timer
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* HRTIMER_CB_IRQSAFE_NO_SOFTIRQ: Callback must run in softirq context
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* Special mode for tick emultation
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*/
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enum hrtimer_cb_mode {
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HRTIMER_CB_SOFTIRQ,
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HRTIMER_CB_IRQSAFE,
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HRTIMER_CB_IRQSAFE_NO_RESTART,
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HRTIMER_CB_IRQSAFE_NO_SOFTIRQ,
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};
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/*
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* Values to track state of the timer
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*
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* Possible states:
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*
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* 0x00 inactive
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* 0x01 enqueued into rbtree
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* 0x02 callback function running
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* 0x04 callback pending (high resolution mode)
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*
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* Special case:
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* 0x03 callback function running and enqueued
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* (was requeued on another CPU)
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*
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* The "callback function running and enqueued" status is only possible on
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* SMP. It happens for example when a posix timer expired and the callback
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* queued a signal. Between dropping the lock which protects the posix timer
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@ -67,6 +86,7 @@ enum hrtimer_restart {
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#define HRTIMER_STATE_INACTIVE 0x00
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#define HRTIMER_STATE_ENQUEUED 0x01
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#define HRTIMER_STATE_CALLBACK 0x02
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#define HRTIMER_STATE_PENDING 0x04
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/**
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* struct hrtimer - the basic hrtimer structure
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@ -77,8 +97,17 @@ enum hrtimer_restart {
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* @function: timer expiry callback function
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* @base: pointer to the timer base (per cpu and per clock)
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* @state: state information (See bit values above)
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* @cb_mode: high resolution timer feature to select the callback execution
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* mode
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* @cb_entry: list head to enqueue an expired timer into the callback list
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* @start_site: timer statistics field to store the site where the timer
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* was started
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* @start_comm: timer statistics field to store the name of the process which
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* started the timer
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* @start_pid: timer statistics field to store the pid of the task which
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* started the timer
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*
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* The hrtimer structure must be initialized by init_hrtimer_#CLOCKTYPE()
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* The hrtimer structure must be initialized by hrtimer_init()
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*/
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struct hrtimer {
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struct rb_node node;
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@ -86,6 +115,10 @@ struct hrtimer {
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enum hrtimer_restart (*function)(struct hrtimer *);
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struct hrtimer_clock_base *base;
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unsigned long state;
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#ifdef CONFIG_HIGH_RES_TIMERS
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enum hrtimer_cb_mode cb_mode;
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struct list_head cb_entry;
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#endif
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};
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/**
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@ -110,6 +143,9 @@ struct hrtimer_sleeper {
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* @get_time: function to retrieve the current time of the clock
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* @get_softirq_time: function to retrieve the current time from the softirq
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* @softirq_time: the time when running the hrtimer queue in the softirq
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* @cb_pending: list of timers where the callback is pending
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* @offset: offset of this clock to the monotonic base
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* @reprogram: function to reprogram the timer event
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*/
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struct hrtimer_clock_base {
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struct hrtimer_cpu_base *cpu_base;
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@ -120,6 +156,12 @@ struct hrtimer_clock_base {
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ktime_t (*get_time)(void);
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ktime_t (*get_softirq_time)(void);
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ktime_t softirq_time;
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#ifdef CONFIG_HIGH_RES_TIMERS
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ktime_t offset;
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int (*reprogram)(struct hrtimer *t,
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struct hrtimer_clock_base *b,
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ktime_t n);
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#endif
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};
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#define HRTIMER_MAX_CLOCK_BASES 2
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@ -131,19 +173,74 @@ struct hrtimer_clock_base {
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* @lock_key: the lock_class_key for use with lockdep
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* @clock_base: array of clock bases for this cpu
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* @curr_timer: the timer which is executing a callback right now
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* @expires_next: absolute time of the next event which was scheduled
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* via clock_set_next_event()
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* @hres_active: State of high resolution mode
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* @check_clocks: Indictator, when set evaluate time source and clock
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* event devices whether high resolution mode can be
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* activated.
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* @cb_pending: Expired timers are moved from the rbtree to this
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* list in the timer interrupt. The list is processed
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* in the softirq.
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* @nr_events: Total number of timer interrupt events
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*/
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struct hrtimer_cpu_base {
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spinlock_t lock;
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struct lock_class_key lock_key;
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struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
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#ifdef CONFIG_HIGH_RES_TIMERS
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ktime_t expires_next;
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int hres_active;
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struct list_head cb_pending;
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unsigned long nr_events;
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#endif
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};
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#ifdef CONFIG_HIGH_RES_TIMERS
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struct clock_event_device;
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extern void clock_was_set(void);
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extern void hrtimer_interrupt(struct clock_event_device *dev);
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/*
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* In high resolution mode the time reference must be read accurate
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*/
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static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
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{
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return timer->base->get_time();
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}
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/*
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* The resolution of the clocks. The resolution value is returned in
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* the clock_getres() system call to give application programmers an
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* idea of the (in)accuracy of timers. Timer values are rounded up to
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* this resolution values.
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*/
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# define KTIME_HIGH_RES (ktime_t) { .tv64 = 1 }
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# define KTIME_MONOTONIC_RES KTIME_HIGH_RES
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#else
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# define KTIME_MONOTONIC_RES KTIME_LOW_RES
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/*
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* clock_was_set() is a NOP for non- high-resolution systems. The
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* time-sorted order guarantees that a timer does not expire early and
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* is expired in the next softirq when the clock was advanced.
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*/
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#define clock_was_set() do { } while (0)
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static inline void clock_was_set(void) { }
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/*
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* In non high resolution mode the time reference is taken from
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* the base softirq time variable.
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*/
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static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
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{
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return timer->base->softirq_time;
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}
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#endif
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extern ktime_t ktime_get(void);
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extern ktime_t ktime_get_real(void);
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@ -168,9 +265,7 @@ static inline int hrtimer_restart(struct hrtimer *timer)
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extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
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extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
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#ifdef CONFIG_NO_IDLE_HZ
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extern ktime_t hrtimer_get_next_event(void);
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#endif
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/*
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* A timer is active, when it is enqueued into the rbtree or the callback
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@ -181,6 +276,15 @@ static inline int hrtimer_active(const struct hrtimer *timer)
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return timer->state != HRTIMER_STATE_INACTIVE;
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}
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/*
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* Helper function to check, whether the timer is on one of the queues
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*/
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static inline int hrtimer_is_queued(struct hrtimer *timer)
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{
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return timer->state &
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(HRTIMER_STATE_ENQUEUED | HRTIMER_STATE_PENDING);
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}
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/* Forward a hrtimer so it expires after now: */
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extern unsigned long
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hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
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@ -242,6 +242,9 @@ enum
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BLOCK_SOFTIRQ,
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TASKLET_SOFTIRQ,
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SCHED_SOFTIRQ,
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#ifdef CONFIG_HIGH_RES_TIMERS
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HRTIMER_SOFTIRQ,
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#endif
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};
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/* softirq mask and active fields moved to irq_cpustat_t in
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@ -261,8 +261,7 @@ static inline s64 ktime_to_ns(const ktime_t kt)
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* idea of the (in)accuracy of timers. Timer values are rounded up to
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* this resolution values.
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*/
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#define KTIME_REALTIME_RES (ktime_t){ .tv64 = TICK_NSEC }
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#define KTIME_MONOTONIC_RES (ktime_t){ .tv64 = TICK_NSEC }
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#define KTIME_LOW_RES (ktime_t){ .tv64 = TICK_NSEC }
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/* Get the monotonic time in timespec format: */
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extern void ktime_get_ts(struct timespec *ts);
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568
kernel/hrtimer.c
568
kernel/hrtimer.c
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@ -3,7 +3,7 @@
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*
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* Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
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* Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
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* Copyright(C) 2006-2007 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
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* Copyright(C) 2006-2007 Timesys Corp., Thomas Gleixner
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*
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* High-resolution kernel timers
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*
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@ -32,13 +32,17 @@
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*/
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#include <linux/cpu.h>
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#include <linux/irq.h>
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#include <linux/module.h>
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#include <linux/percpu.h>
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#include <linux/hrtimer.h>
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#include <linux/notifier.h>
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#include <linux/syscalls.h>
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#include <linux/kallsyms.h>
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#include <linux/interrupt.h>
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#include <linux/tick.h>
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#include <linux/seq_file.h>
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#include <linux/err.h>
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#include <asm/uaccess.h>
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@ -81,7 +85,7 @@ EXPORT_SYMBOL_GPL(ktime_get_real);
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* This ensures that we capture erroneous accesses to these clock ids
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* rather than moving them into the range of valid clock id's.
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*/
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static DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
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DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
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{
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.clock_base =
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@ -89,12 +93,12 @@ static DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
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{
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.index = CLOCK_REALTIME,
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.get_time = &ktime_get_real,
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.resolution = KTIME_REALTIME_RES,
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.resolution = KTIME_LOW_RES,
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},
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{
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.index = CLOCK_MONOTONIC,
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.get_time = &ktime_get,
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.resolution = KTIME_MONOTONIC_RES,
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.resolution = KTIME_LOW_RES,
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},
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}
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};
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@ -150,14 +154,6 @@ static void hrtimer_get_softirq_time(struct hrtimer_cpu_base *base)
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ktime_add(xtim, tomono);
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}
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/*
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* Helper function to check, whether the timer is on one of the queues
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*/
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static inline int hrtimer_is_queued(struct hrtimer *timer)
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{
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return timer->state & HRTIMER_STATE_ENQUEUED;
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}
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/*
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* Helper function to check, whether the timer is running the callback
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* function
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@ -226,7 +222,7 @@ switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base)
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* completed. There is no conflict as we hold the lock until
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* the timer is enqueued.
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*/
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if (unlikely(timer->state & HRTIMER_STATE_CALLBACK))
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if (unlikely(hrtimer_callback_running(timer)))
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return base;
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/* See the comment in lock_timer_base() */
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@ -250,7 +246,7 @@ lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
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return base;
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}
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#define switch_hrtimer_base(t, b) (b)
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# define switch_hrtimer_base(t, b) (b)
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#endif /* !CONFIG_SMP */
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@ -281,9 +277,6 @@ ktime_t ktime_add_ns(const ktime_t kt, u64 nsec)
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return ktime_add(kt, tmp);
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}
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#else /* CONFIG_KTIME_SCALAR */
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# endif /* !CONFIG_KTIME_SCALAR */
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/*
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@ -308,6 +301,290 @@ unsigned long ktime_divns(const ktime_t kt, s64 div)
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}
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#endif /* BITS_PER_LONG >= 64 */
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/* High resolution timer related functions */
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#ifdef CONFIG_HIGH_RES_TIMERS
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/*
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* High resolution timer enabled ?
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*/
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static int hrtimer_hres_enabled __read_mostly = 1;
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/*
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* Enable / Disable high resolution mode
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*/
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static int __init setup_hrtimer_hres(char *str)
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{
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if (!strcmp(str, "off"))
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hrtimer_hres_enabled = 0;
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else if (!strcmp(str, "on"))
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hrtimer_hres_enabled = 1;
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else
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return 0;
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return 1;
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}
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__setup("highres=", setup_hrtimer_hres);
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/*
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* hrtimer_high_res_enabled - query, if the highres mode is enabled
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*/
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static inline int hrtimer_is_hres_enabled(void)
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{
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return hrtimer_hres_enabled;
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}
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/*
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* Is the high resolution mode active ?
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*/
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static inline int hrtimer_hres_active(void)
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{
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return __get_cpu_var(hrtimer_bases).hres_active;
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}
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/*
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* Reprogram the event source with checking both queues for the
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* next event
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* Called with interrupts disabled and base->lock held
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*/
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static void hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base)
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{
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int i;
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struct hrtimer_clock_base *base = cpu_base->clock_base;
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ktime_t expires;
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cpu_base->expires_next.tv64 = KTIME_MAX;
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for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
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struct hrtimer *timer;
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if (!base->first)
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continue;
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timer = rb_entry(base->first, struct hrtimer, node);
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expires = ktime_sub(timer->expires, base->offset);
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if (expires.tv64 < cpu_base->expires_next.tv64)
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cpu_base->expires_next = expires;
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}
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if (cpu_base->expires_next.tv64 != KTIME_MAX)
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tick_program_event(cpu_base->expires_next, 1);
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}
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/*
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* Shared reprogramming for clock_realtime and clock_monotonic
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*
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* When a timer is enqueued and expires earlier than the already enqueued
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* timers, we have to check, whether it expires earlier than the timer for
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* which the clock event device was armed.
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*
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* Called with interrupts disabled and base->cpu_base.lock held
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*/
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static int hrtimer_reprogram(struct hrtimer *timer,
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struct hrtimer_clock_base *base)
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{
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ktime_t *expires_next = &__get_cpu_var(hrtimer_bases).expires_next;
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ktime_t expires = ktime_sub(timer->expires, base->offset);
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int res;
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/*
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* When the callback is running, we do not reprogram the clock event
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* device. The timer callback is either running on a different CPU or
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* the callback is executed in the hrtimer_interupt context. The
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* reprogramming is handled either by the softirq, which called the
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* callback or at the end of the hrtimer_interrupt.
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*/
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if (hrtimer_callback_running(timer))
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return 0;
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if (expires.tv64 >= expires_next->tv64)
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return 0;
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/*
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* Clockevents returns -ETIME, when the event was in the past.
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*/
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res = tick_program_event(expires, 0);
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if (!IS_ERR_VALUE(res))
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*expires_next = expires;
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return res;
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}
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/*
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* Retrigger next event is called after clock was set
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*
|
||||
* Called with interrupts disabled via on_each_cpu()
|
||||
*/
|
||||
static void retrigger_next_event(void *arg)
|
||||
{
|
||||
struct hrtimer_cpu_base *base;
|
||||
struct timespec realtime_offset;
|
||||
unsigned long seq;
|
||||
|
||||
if (!hrtimer_hres_active())
|
||||
return;
|
||||
|
||||
do {
|
||||
seq = read_seqbegin(&xtime_lock);
|
||||
set_normalized_timespec(&realtime_offset,
|
||||
-wall_to_monotonic.tv_sec,
|
||||
-wall_to_monotonic.tv_nsec);
|
||||
} while (read_seqretry(&xtime_lock, seq));
|
||||
|
||||
base = &__get_cpu_var(hrtimer_bases);
|
||||
|
||||
/* Adjust CLOCK_REALTIME offset */
|
||||
spin_lock(&base->lock);
|
||||
base->clock_base[CLOCK_REALTIME].offset =
|
||||
timespec_to_ktime(realtime_offset);
|
||||
|
||||
hrtimer_force_reprogram(base);
|
||||
spin_unlock(&base->lock);
|
||||
}
|
||||
|
||||
/*
|
||||
* Clock realtime was set
|
||||
*
|
||||
* Change the offset of the realtime clock vs. the monotonic
|
||||
* clock.
|
||||
*
|
||||
* We might have to reprogram the high resolution timer interrupt. On
|
||||
* SMP we call the architecture specific code to retrigger _all_ high
|
||||
* resolution timer interrupts. On UP we just disable interrupts and
|
||||
* call the high resolution interrupt code.
|
||||
*/
|
||||
void clock_was_set(void)
|
||||
{
|
||||
/* Retrigger the CPU local events everywhere */
|
||||
on_each_cpu(retrigger_next_event, NULL, 0, 1);
|
||||
}
|
||||
|
||||
/*
|
||||
* Check, whether the timer is on the callback pending list
|
||||
*/
|
||||
static inline int hrtimer_cb_pending(const struct hrtimer *timer)
|
||||
{
|
||||
return timer->state & HRTIMER_STATE_PENDING;
|
||||
}
|
||||
|
||||
/*
|
||||
* Remove a timer from the callback pending list
|
||||
*/
|
||||
static inline void hrtimer_remove_cb_pending(struct hrtimer *timer)
|
||||
{
|
||||
list_del_init(&timer->cb_entry);
|
||||
}
|
||||
|
||||
/*
|
||||
* Initialize the high resolution related parts of cpu_base
|
||||
*/
|
||||
static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base)
|
||||
{
|
||||
base->expires_next.tv64 = KTIME_MAX;
|
||||
base->hres_active = 0;
|
||||
INIT_LIST_HEAD(&base->cb_pending);
|
||||
}
|
||||
|
||||
/*
|
||||
* Initialize the high resolution related parts of a hrtimer
|
||||
*/
|
||||
static inline void hrtimer_init_timer_hres(struct hrtimer *timer)
|
||||
{
|
||||
INIT_LIST_HEAD(&timer->cb_entry);
|
||||
}
|
||||
|
||||
/*
|
||||
* When High resolution timers are active, try to reprogram. Note, that in case
|
||||
* the state has HRTIMER_STATE_CALLBACK set, no reprogramming and no expiry
|
||||
* check happens. The timer gets enqueued into the rbtree. The reprogramming
|
||||
* and expiry check is done in the hrtimer_interrupt or in the softirq.
|
||||
*/
|
||||
static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
|
||||
struct hrtimer_clock_base *base)
|
||||
{
|
||||
if (base->cpu_base->hres_active && hrtimer_reprogram(timer, base)) {
|
||||
|
||||
/* Timer is expired, act upon the callback mode */
|
||||
switch(timer->cb_mode) {
|
||||
case HRTIMER_CB_IRQSAFE_NO_RESTART:
|
||||
/*
|
||||
* We can call the callback from here. No restart
|
||||
* happens, so no danger of recursion
|
||||
*/
|
||||
BUG_ON(timer->function(timer) != HRTIMER_NORESTART);
|
||||
return 1;
|
||||
case HRTIMER_CB_IRQSAFE_NO_SOFTIRQ:
|
||||
/*
|
||||
* This is solely for the sched tick emulation with
|
||||
* dynamic tick support to ensure that we do not
|
||||
* restart the tick right on the edge and end up with
|
||||
* the tick timer in the softirq ! The calling site
|
||||
* takes care of this.
|
||||
*/
|
||||
return 1;
|
||||
case HRTIMER_CB_IRQSAFE:
|
||||
case HRTIMER_CB_SOFTIRQ:
|
||||
/*
|
||||
* Move everything else into the softirq pending list !
|
||||
*/
|
||||
list_add_tail(&timer->cb_entry,
|
||||
&base->cpu_base->cb_pending);
|
||||
timer->state = HRTIMER_STATE_PENDING;
|
||||
raise_softirq(HRTIMER_SOFTIRQ);
|
||||
return 1;
|
||||
default:
|
||||
BUG();
|
||||
}
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
||||
/*
|
||||
* Switch to high resolution mode
|
||||
*/
|
||||
static void hrtimer_switch_to_hres(void)
|
||||
{
|
||||
struct hrtimer_cpu_base *base = &__get_cpu_var(hrtimer_bases);
|
||||
unsigned long flags;
|
||||
|
||||
if (base->hres_active)
|
||||
return;
|
||||
|
||||
local_irq_save(flags);
|
||||
|
||||
if (tick_init_highres()) {
|
||||
local_irq_restore(flags);
|
||||
return;
|
||||
}
|
||||
base->hres_active = 1;
|
||||
base->clock_base[CLOCK_REALTIME].resolution = KTIME_HIGH_RES;
|
||||
base->clock_base[CLOCK_MONOTONIC].resolution = KTIME_HIGH_RES;
|
||||
|
||||
tick_setup_sched_timer();
|
||||
|
||||
/* "Retrigger" the interrupt to get things going */
|
||||
retrigger_next_event(NULL);
|
||||
local_irq_restore(flags);
|
||||
printk(KERN_INFO "Switched to high resolution mode on CPU %d\n",
|
||||
smp_processor_id());
|
||||
}
|
||||
|
||||
#else
|
||||
|
||||
static inline int hrtimer_hres_active(void) { return 0; }
|
||||
static inline int hrtimer_is_hres_enabled(void) { return 0; }
|
||||
static inline void hrtimer_switch_to_hres(void) { }
|
||||
static inline void hrtimer_force_reprogram(struct hrtimer_cpu_base *base) { }
|
||||
static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
|
||||
struct hrtimer_clock_base *base)
|
||||
{
|
||||
return 0;
|
||||
}
|
||||
static inline int hrtimer_cb_pending(struct hrtimer *timer) { return 0; }
|
||||
static inline void hrtimer_remove_cb_pending(struct hrtimer *timer) { }
|
||||
static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) { }
|
||||
static inline void hrtimer_init_timer_hres(struct hrtimer *timer) { }
|
||||
|
||||
#endif /* CONFIG_HIGH_RES_TIMERS */
|
||||
|
||||
/*
|
||||
* Counterpart to lock_timer_base above:
|
||||
*/
|
||||
|
|
@ -365,7 +642,7 @@ hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
|
|||
* red black tree is O(log(n)). Must hold the base lock.
|
||||
*/
|
||||
static void enqueue_hrtimer(struct hrtimer *timer,
|
||||
struct hrtimer_clock_base *base)
|
||||
struct hrtimer_clock_base *base, int reprogram)
|
||||
{
|
||||
struct rb_node **link = &base->active.rb_node;
|
||||
struct rb_node *parent = NULL;
|
||||
|
|
@ -391,6 +668,22 @@ static void enqueue_hrtimer(struct hrtimer *timer,
|
|||
* Insert the timer to the rbtree and check whether it
|
||||
* replaces the first pending timer
|
||||
*/
|
||||
if (!base->first || timer->expires.tv64 <
|
||||
rb_entry(base->first, struct hrtimer, node)->expires.tv64) {
|
||||
/*
|
||||
* Reprogram the clock event device. When the timer is already
|
||||
* expired hrtimer_enqueue_reprogram has either called the
|
||||
* callback or added it to the pending list and raised the
|
||||
* softirq.
|
||||
*
|
||||
* This is a NOP for !HIGHRES
|
||||
*/
|
||||
if (reprogram && hrtimer_enqueue_reprogram(timer, base))
|
||||
return;
|
||||
|
||||
base->first = &timer->node;
|
||||
}
|
||||
|
||||
rb_link_node(&timer->node, parent, link);
|
||||
rb_insert_color(&timer->node, &base->active);
|
||||
/*
|
||||
|
|
@ -398,28 +691,38 @@ static void enqueue_hrtimer(struct hrtimer *timer,
|
|||
* state of a possibly running callback.
|
||||
*/
|
||||
timer->state |= HRTIMER_STATE_ENQUEUED;
|
||||
|
||||
if (!base->first || timer->expires.tv64 <
|
||||
rb_entry(base->first, struct hrtimer, node)->expires.tv64)
|
||||
base->first = &timer->node;
|
||||
}
|
||||
|
||||
/*
|
||||
* __remove_hrtimer - internal function to remove a timer
|
||||
*
|
||||
* Caller must hold the base lock.
|
||||
*
|
||||
* High resolution timer mode reprograms the clock event device when the
|
||||
* timer is the one which expires next. The caller can disable this by setting
|
||||
* reprogram to zero. This is useful, when the context does a reprogramming
|
||||
* anyway (e.g. timer interrupt)
|
||||
*/
|
||||
static void __remove_hrtimer(struct hrtimer *timer,
|
||||
struct hrtimer_clock_base *base,
|
||||
unsigned long newstate)
|
||||
unsigned long newstate, int reprogram)
|
||||
{
|
||||
/*
|
||||
* Remove the timer from the rbtree and replace the
|
||||
* first entry pointer if necessary.
|
||||
*/
|
||||
if (base->first == &timer->node)
|
||||
base->first = rb_next(&timer->node);
|
||||
rb_erase(&timer->node, &base->active);
|
||||
/* High res. callback list. NOP for !HIGHRES */
|
||||
if (hrtimer_cb_pending(timer))
|
||||
hrtimer_remove_cb_pending(timer);
|
||||
else {
|
||||
/*
|
||||
* Remove the timer from the rbtree and replace the
|
||||
* first entry pointer if necessary.
|
||||
*/
|
||||
if (base->first == &timer->node) {
|
||||
base->first = rb_next(&timer->node);
|
||||
/* Reprogram the clock event device. if enabled */
|
||||
if (reprogram && hrtimer_hres_active())
|
||||
hrtimer_force_reprogram(base->cpu_base);
|
||||
}
|
||||
rb_erase(&timer->node, &base->active);
|
||||
}
|
||||
timer->state = newstate;
|
||||
}
|
||||
|
||||
|
|
@ -430,7 +733,19 @@ static inline int
|
|||
remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base)
|
||||
{
|
||||
if (hrtimer_is_queued(timer)) {
|
||||
__remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE);
|
||||
int reprogram;
|
||||
|
||||
/*
|
||||
* Remove the timer and force reprogramming when high
|
||||
* resolution mode is active and the timer is on the current
|
||||
* CPU. If we remove a timer on another CPU, reprogramming is
|
||||
* skipped. The interrupt event on this CPU is fired and
|
||||
* reprogramming happens in the interrupt handler. This is a
|
||||
* rare case and less expensive than a smp call.
|
||||
*/
|
||||
reprogram = base->cpu_base == &__get_cpu_var(hrtimer_bases);
|
||||
__remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE,
|
||||
reprogram);
|
||||
return 1;
|
||||
}
|
||||
return 0;
|
||||
|
|
@ -476,7 +791,7 @@ hrtimer_start(struct hrtimer *timer, ktime_t tim, const enum hrtimer_mode mode)
|
|||
}
|
||||
timer->expires = tim;
|
||||
|
||||
enqueue_hrtimer(timer, new_base);
|
||||
enqueue_hrtimer(timer, new_base, base == new_base);
|
||||
|
||||
unlock_hrtimer_base(timer, &flags);
|
||||
|
||||
|
|
@ -567,17 +882,19 @@ ktime_t hrtimer_get_next_event(void)
|
|||
|
||||
spin_lock_irqsave(&cpu_base->lock, flags);
|
||||
|
||||
for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
|
||||
struct hrtimer *timer;
|
||||
if (!hrtimer_hres_active()) {
|
||||
for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
|
||||
struct hrtimer *timer;
|
||||
|
||||
if (!base->first)
|
||||
continue;
|
||||
if (!base->first)
|
||||
continue;
|
||||
|
||||
timer = rb_entry(base->first, struct hrtimer, node);
|
||||
delta.tv64 = timer->expires.tv64;
|
||||
delta = ktime_sub(delta, base->get_time());
|
||||
if (delta.tv64 < mindelta.tv64)
|
||||
mindelta.tv64 = delta.tv64;
|
||||
timer = rb_entry(base->first, struct hrtimer, node);
|
||||
delta.tv64 = timer->expires.tv64;
|
||||
delta = ktime_sub(delta, base->get_time());
|
||||
if (delta.tv64 < mindelta.tv64)
|
||||
mindelta.tv64 = delta.tv64;
|
||||
}
|
||||
}
|
||||
|
||||
spin_unlock_irqrestore(&cpu_base->lock, flags);
|
||||
|
|
@ -607,6 +924,7 @@ void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
|
|||
clock_id = CLOCK_MONOTONIC;
|
||||
|
||||
timer->base = &cpu_base->clock_base[clock_id];
|
||||
hrtimer_init_timer_hres(timer);
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(hrtimer_init);
|
||||
|
||||
|
|
@ -629,6 +947,139 @@ int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp)
|
|||
}
|
||||
EXPORT_SYMBOL_GPL(hrtimer_get_res);
|
||||
|
||||
#ifdef CONFIG_HIGH_RES_TIMERS
|
||||
|
||||
/*
|
||||
* High resolution timer interrupt
|
||||
* Called with interrupts disabled
|
||||
*/
|
||||
void hrtimer_interrupt(struct clock_event_device *dev)
|
||||
{
|
||||
struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
|
||||
struct hrtimer_clock_base *base;
|
||||
ktime_t expires_next, now;
|
||||
int i, raise = 0;
|
||||
|
||||
BUG_ON(!cpu_base->hres_active);
|
||||
cpu_base->nr_events++;
|
||||
dev->next_event.tv64 = KTIME_MAX;
|
||||
|
||||
retry:
|
||||
now = ktime_get();
|
||||
|
||||
expires_next.tv64 = KTIME_MAX;
|
||||
|
||||
base = cpu_base->clock_base;
|
||||
|
||||
for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
|
||||
ktime_t basenow;
|
||||
struct rb_node *node;
|
||||
|
||||
spin_lock(&cpu_base->lock);
|
||||
|
||||
basenow = ktime_add(now, base->offset);
|
||||
|
||||
while ((node = base->first)) {
|
||||
struct hrtimer *timer;
|
||||
|
||||
timer = rb_entry(node, struct hrtimer, node);
|
||||
|
||||
if (basenow.tv64 < timer->expires.tv64) {
|
||||
ktime_t expires;
|
||||
|
||||
expires = ktime_sub(timer->expires,
|
||||
base->offset);
|
||||
if (expires.tv64 < expires_next.tv64)
|
||||
expires_next = expires;
|
||||
break;
|
||||
}
|
||||
|
||||
/* Move softirq callbacks to the pending list */
|
||||
if (timer->cb_mode == HRTIMER_CB_SOFTIRQ) {
|
||||
__remove_hrtimer(timer, base,
|
||||
HRTIMER_STATE_PENDING, 0);
|
||||
list_add_tail(&timer->cb_entry,
|
||||
&base->cpu_base->cb_pending);
|
||||
raise = 1;
|
||||
continue;
|
||||
}
|
||||
|
||||
__remove_hrtimer(timer, base,
|
||||
HRTIMER_STATE_CALLBACK, 0);
|
||||
|
||||
/*
|
||||
* Note: We clear the CALLBACK bit after
|
||||
* enqueue_hrtimer to avoid reprogramming of
|
||||
* the event hardware. This happens at the end
|
||||
* of this function anyway.
|
||||
*/
|
||||
if (timer->function(timer) != HRTIMER_NORESTART) {
|
||||
BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
|
||||
enqueue_hrtimer(timer, base, 0);
|
||||
}
|
||||
timer->state &= ~HRTIMER_STATE_CALLBACK;
|
||||
}
|
||||
spin_unlock(&cpu_base->lock);
|
||||
base++;
|
||||
}
|
||||
|
||||
cpu_base->expires_next = expires_next;
|
||||
|
||||
/* Reprogramming necessary ? */
|
||||
if (expires_next.tv64 != KTIME_MAX) {
|
||||
if (tick_program_event(expires_next, 0))
|
||||
goto retry;
|
||||
}
|
||||
|
||||
/* Raise softirq ? */
|
||||
if (raise)
|
||||
raise_softirq(HRTIMER_SOFTIRQ);
|
||||
}
|
||||
|
||||
static void run_hrtimer_softirq(struct softirq_action *h)
|
||||
{
|
||||
struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
|
||||
|
||||
spin_lock_irq(&cpu_base->lock);
|
||||
|
||||
while (!list_empty(&cpu_base->cb_pending)) {
|
||||
enum hrtimer_restart (*fn)(struct hrtimer *);
|
||||
struct hrtimer *timer;
|
||||
int restart;
|
||||
|
||||
timer = list_entry(cpu_base->cb_pending.next,
|
||||
struct hrtimer, cb_entry);
|
||||
|
||||
fn = timer->function;
|
||||
__remove_hrtimer(timer, timer->base, HRTIMER_STATE_CALLBACK, 0);
|
||||
spin_unlock_irq(&cpu_base->lock);
|
||||
|
||||
restart = fn(timer);
|
||||
|
||||
spin_lock_irq(&cpu_base->lock);
|
||||
|
||||
timer->state &= ~HRTIMER_STATE_CALLBACK;
|
||||
if (restart == HRTIMER_RESTART) {
|
||||
BUG_ON(hrtimer_active(timer));
|
||||
/*
|
||||
* Enqueue the timer, allow reprogramming of the event
|
||||
* device
|
||||
*/
|
||||
enqueue_hrtimer(timer, timer->base, 1);
|
||||
} else if (hrtimer_active(timer)) {
|
||||
/*
|
||||
* If the timer was rearmed on another CPU, reprogram
|
||||
* the event device.
|
||||
*/
|
||||
if (timer->base->first == &timer->node)
|
||||
hrtimer_reprogram(timer, timer->base);
|
||||
}
|
||||
}
|
||||
spin_unlock_irq(&cpu_base->lock);
|
||||
}
|
||||
|
||||
#endif /* CONFIG_HIGH_RES_TIMERS */
|
||||
|
||||
/*
|
||||
* Expire the per base hrtimer-queue:
|
||||
*/
|
||||
|
|
@ -656,7 +1107,7 @@ static inline void run_hrtimer_queue(struct hrtimer_cpu_base *cpu_base,
|
|||
break;
|
||||
|
||||
fn = timer->function;
|
||||
__remove_hrtimer(timer, base, HRTIMER_STATE_CALLBACK);
|
||||
__remove_hrtimer(timer, base, HRTIMER_STATE_CALLBACK, 0);
|
||||
spin_unlock_irq(&cpu_base->lock);
|
||||
|
||||
restart = fn(timer);
|
||||
|
|
@ -666,7 +1117,7 @@ static inline void run_hrtimer_queue(struct hrtimer_cpu_base *cpu_base,
|
|||
timer->state &= ~HRTIMER_STATE_CALLBACK;
|
||||
if (restart != HRTIMER_NORESTART) {
|
||||
BUG_ON(hrtimer_active(timer));
|
||||
enqueue_hrtimer(timer, base);
|
||||
enqueue_hrtimer(timer, base, 0);
|
||||
}
|
||||
}
|
||||
spin_unlock_irq(&cpu_base->lock);
|
||||
|
|
@ -674,12 +1125,19 @@ static inline void run_hrtimer_queue(struct hrtimer_cpu_base *cpu_base,
|
|||
|
||||
/*
|
||||
* Called from timer softirq every jiffy, expire hrtimers:
|
||||
*
|
||||
* For HRT its the fall back code to run the softirq in the timer
|
||||
* softirq context in case the hrtimer initialization failed or has
|
||||
* not been done yet.
|
||||
*/
|
||||
void hrtimer_run_queues(void)
|
||||
{
|
||||
struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
|
||||
int i;
|
||||
|
||||
if (hrtimer_hres_active())
|
||||
return;
|
||||
|
||||
/*
|
||||
* This _is_ ugly: We have to check in the softirq context,
|
||||
* whether we can switch to highres and / or nohz mode. The
|
||||
|
|
@ -688,7 +1146,8 @@ void hrtimer_run_queues(void)
|
|||
* check bit in the tick_oneshot code, otherwise we might
|
||||
* deadlock vs. xtime_lock.
|
||||
*/
|
||||
tick_check_oneshot_change(1);
|
||||
if (tick_check_oneshot_change(!hrtimer_is_hres_enabled()))
|
||||
hrtimer_switch_to_hres();
|
||||
|
||||
hrtimer_get_softirq_time(cpu_base);
|
||||
|
||||
|
|
@ -716,6 +1175,9 @@ void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, struct task_struct *task)
|
|||
{
|
||||
sl->timer.function = hrtimer_wakeup;
|
||||
sl->task = task;
|
||||
#ifdef CONFIG_HIGH_RES_TIMERS
|
||||
sl->timer.cb_mode = HRTIMER_CB_IRQSAFE_NO_RESTART;
|
||||
#endif
|
||||
}
|
||||
|
||||
static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
|
||||
|
|
@ -726,7 +1188,8 @@ static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mod
|
|||
set_current_state(TASK_INTERRUPTIBLE);
|
||||
hrtimer_start(&t->timer, t->timer.expires, mode);
|
||||
|
||||
schedule();
|
||||
if (likely(t->task))
|
||||
schedule();
|
||||
|
||||
hrtimer_cancel(&t->timer);
|
||||
mode = HRTIMER_MODE_ABS;
|
||||
|
|
@ -831,6 +1294,7 @@ static void __devinit init_hrtimers_cpu(int cpu)
|
|||
for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++)
|
||||
cpu_base->clock_base[i].cpu_base = cpu_base;
|
||||
|
||||
hrtimer_init_hres(cpu_base);
|
||||
}
|
||||
|
||||
#ifdef CONFIG_HOTPLUG_CPU
|
||||
|
|
@ -843,10 +1307,13 @@ static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
|
|||
|
||||
while ((node = rb_first(&old_base->active))) {
|
||||
timer = rb_entry(node, struct hrtimer, node);
|
||||
BUG_ON(timer->state & HRTIMER_STATE_CALLBACK);
|
||||
__remove_hrtimer(timer, old_base, HRTIMER_STATE_INACTIVE);
|
||||
BUG_ON(hrtimer_callback_running(timer));
|
||||
__remove_hrtimer(timer, old_base, HRTIMER_STATE_INACTIVE, 0);
|
||||
timer->base = new_base;
|
||||
enqueue_hrtimer(timer, new_base);
|
||||
/*
|
||||
* Enqueue the timer. Allow reprogramming of the event device
|
||||
*/
|
||||
enqueue_hrtimer(timer, new_base, 1);
|
||||
}
|
||||
}
|
||||
|
||||
|
|
@ -859,6 +1326,8 @@ static void migrate_hrtimers(int cpu)
|
|||
old_base = &per_cpu(hrtimer_bases, cpu);
|
||||
new_base = &get_cpu_var(hrtimer_bases);
|
||||
|
||||
tick_cancel_sched_timer(cpu);
|
||||
|
||||
local_irq_disable();
|
||||
|
||||
spin_lock(&new_base->lock);
|
||||
|
|
@ -910,5 +1379,8 @@ void __init hrtimers_init(void)
|
|||
hrtimer_cpu_notify(&hrtimers_nb, (unsigned long)CPU_UP_PREPARE,
|
||||
(void *)(long)smp_processor_id());
|
||||
register_cpu_notifier(&hrtimers_nb);
|
||||
#ifdef CONFIG_HIGH_RES_TIMERS
|
||||
open_softirq(HRTIMER_SOFTIRQ, run_hrtimer_softirq, NULL);
|
||||
#endif
|
||||
}
|
||||
|
||||
|
|
|
|||
|
|
@ -136,7 +136,7 @@ enum hrtimer_restart it_real_fn(struct hrtimer *timer)
|
|||
send_group_sig_info(SIGALRM, SEND_SIG_PRIV, sig->tsk);
|
||||
|
||||
if (sig->it_real_incr.tv64 != 0) {
|
||||
hrtimer_forward(timer, timer->base->softirq_time,
|
||||
hrtimer_forward(timer, hrtimer_cb_get_time(timer),
|
||||
sig->it_real_incr);
|
||||
return HRTIMER_RESTART;
|
||||
}
|
||||
|
|
|
|||
|
|
@ -356,7 +356,7 @@ static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
|
|||
if (timr->it.real.interval.tv64 != 0) {
|
||||
timr->it_overrun +=
|
||||
hrtimer_forward(timer,
|
||||
timer->base->softirq_time,
|
||||
hrtimer_cb_get_time(timer),
|
||||
timr->it.real.interval);
|
||||
ret = HRTIMER_RESTART;
|
||||
++timr->it_requeue_pending;
|
||||
|
|
|
|||
|
|
@ -13,3 +13,13 @@ config NO_HZ
|
|||
This option enables a tickless system: timer interrupts will
|
||||
only trigger on an as-needed basis both when the system is
|
||||
busy and when the system is idle.
|
||||
|
||||
config HIGH_RES_TIMERS
|
||||
bool "High Resolution Timer Support"
|
||||
depends on GENERIC_TIME && GENERIC_CLOCKEVENTS
|
||||
select TICK_ONESHOT
|
||||
help
|
||||
This option enables high resolution timer support. If your
|
||||
hardware is not capable then this option only increases
|
||||
the size of the kernel image.
|
||||
|
||||
|
|
|
|||
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