diff options
| -rw-r--r-- | Documentation/kernel-parameters.txt | 4 | ||||
| -rw-r--r-- | include/linux/hrtimer.h | 116 | ||||
| -rw-r--r-- | include/linux/interrupt.h | 3 | ||||
| -rw-r--r-- | include/linux/ktime.h | 3 | ||||
| -rw-r--r-- | kernel/hrtimer.c | 568 | ||||
| -rw-r--r-- | kernel/itimer.c | 2 | ||||
| -rw-r--r-- | kernel/posix-timers.c | 2 | ||||
| -rw-r--r-- | kernel/time/Kconfig | 10 |
8 files changed, 650 insertions, 58 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 52bf1ed..abd575c 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -609,6 +609,10 @@ and is between 256 and 4096 characters. It is defined in the file highmem otherwise. This also works to reduce highmem size on bigger boxes. + highres= [KNL] Enable/disable high resolution timer mode. + Valid parameters: "on", "off" + Default: "on" + hisax= [HW,ISDN] See Documentation/isdn/README.HiSax. diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index e95c96c9..4ecd991 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -41,16 +41,35 @@ enum hrtimer_restart { }; /* - * Bit values to track state of the timer + * hrtimer callback modes: + * + * HRTIMER_CB_SOFTIRQ: Callback must run in softirq context + * HRTIMER_CB_IRQSAFE: Callback may run in hardirq context + * HRTIMER_CB_IRQSAFE_NO_RESTART: Callback may run in hardirq context and + * does not restart the timer + * HRTIMER_CB_IRQSAFE_NO_SOFTIRQ: Callback must run in softirq context + * Special mode for tick emultation + */ +enum hrtimer_cb_mode { + HRTIMER_CB_SOFTIRQ, + HRTIMER_CB_IRQSAFE, + HRTIMER_CB_IRQSAFE_NO_RESTART, + HRTIMER_CB_IRQSAFE_NO_SOFTIRQ, +}; + +/* + * Values to track state of the timer * * Possible states: * * 0x00 inactive * 0x01 enqueued into rbtree * 0x02 callback function running + * 0x04 callback pending (high resolution mode) + * + * Special case: * 0x03 callback function running and enqueued * (was requeued on another CPU) - * * The "callback function running and enqueued" status is only possible on * SMP. It happens for example when a posix timer expired and the callback * queued a signal. Between dropping the lock which protects the posix timer @@ -67,6 +86,7 @@ enum hrtimer_restart { #define HRTIMER_STATE_INACTIVE 0x00 #define HRTIMER_STATE_ENQUEUED 0x01 #define HRTIMER_STATE_CALLBACK 0x02 +#define HRTIMER_STATE_PENDING 0x04 /** * struct hrtimer - the basic hrtimer structure @@ -77,8 +97,17 @@ enum hrtimer_restart { * @function: timer expiry callback function * @base: pointer to the timer base (per cpu and per clock) * @state: state information (See bit values above) + * @cb_mode: high resolution timer feature to select the callback execution + * mode + * @cb_entry: list head to enqueue an expired timer into the callback list + * @start_site: timer statistics field to store the site where the timer + * was started + * @start_comm: timer statistics field to store the name of the process which + * started the timer + * @start_pid: timer statistics field to store the pid of the task which + * started the timer * - * The hrtimer structure must be initialized by init_hrtimer_#CLOCKTYPE() + * The hrtimer structure must be initialized by hrtimer_init() */ struct hrtimer { struct rb_node node; @@ -86,6 +115,10 @@ struct hrtimer { enum hrtimer_restart (*function)(struct hrtimer *); struct hrtimer_clock_base *base; unsigned long state; +#ifdef CONFIG_HIGH_RES_TIMERS + enum hrtimer_cb_mode cb_mode; + struct list_head cb_entry; +#endif }; /** @@ -110,6 +143,9 @@ struct hrtimer_sleeper { * @get_time: function to retrieve the current time of the clock * @get_softirq_time: function to retrieve the current time from the softirq * @softirq_time: the time when running the hrtimer queue in the softirq + * @cb_pending: list of timers where the callback is pending + * @offset: offset of this clock to the monotonic base + * @reprogram: function to reprogram the timer event */ struct hrtimer_clock_base { struct hrtimer_cpu_base *cpu_base; @@ -120,6 +156,12 @@ struct hrtimer_clock_base { ktime_t (*get_time)(void); ktime_t (*get_softirq_time)(void); ktime_t softirq_time; +#ifdef CONFIG_HIGH_RES_TIMERS + ktime_t offset; + int (*reprogram)(struct hrtimer *t, + struct hrtimer_clock_base *b, + ktime_t n); +#endif }; #define HRTIMER_MAX_CLOCK_BASES 2 @@ -131,19 +173,74 @@ struct hrtimer_clock_base { * @lock_key: the lock_class_key for use with lockdep * @clock_base: array of clock bases for this cpu * @curr_timer: the timer which is executing a callback right now + * @expires_next: absolute time of the next event which was scheduled + * via clock_set_next_event() + * @hres_active: State of high resolution mode + * @check_clocks: Indictator, when set evaluate time source and clock + * event devices whether high resolution mode can be + * activated. + * @cb_pending: Expired timers are moved from the rbtree to this + * list in the timer interrupt. The list is processed + * in the softirq. + * @nr_events: Total number of timer interrupt events */ struct hrtimer_cpu_base { spinlock_t lock; struct lock_class_key lock_key; struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES]; +#ifdef CONFIG_HIGH_RES_TIMERS + ktime_t expires_next; + int hres_active; + struct list_head cb_pending; + unsigned long nr_events; +#endif }; +#ifdef CONFIG_HIGH_RES_TIMERS +struct clock_event_device; + +extern void clock_was_set(void); +extern void hrtimer_interrupt(struct clock_event_device *dev); + +/* + * In high resolution mode the time reference must be read accurate + */ +static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer) +{ + return timer->base->get_time(); +} + +/* + * The resolution of the clocks. The resolution value is returned in + * the clock_getres() system call to give application programmers an + * idea of the (in)accuracy of timers. Timer values are rounded up to + * this resolution values. + */ +# define KTIME_HIGH_RES (ktime_t) { .tv64 = 1 } +# define KTIME_MONOTONIC_RES KTIME_HIGH_RES + +#else + +# define KTIME_MONOTONIC_RES KTIME_LOW_RES + /* * clock_was_set() is a NOP for non- high-resolution systems. The * time-sorted order guarantees that a timer does not expire early and * is expired in the next softirq when the clock was advanced. */ -#define clock_was_set() do { } while (0) +static inline void clock_was_set(void) { } + +/* + * In non high resolution mode the time reference is taken from + * the base softirq time variable. + */ +static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer) +{ + return timer->base->softirq_time; +} + +#endif + extern ktime_t ktime_get(void); extern ktime_t ktime_get_real(void); @@ -168,9 +265,7 @@ static inline int hrtimer_restart(struct hrtimer *timer) extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer); extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp); -#ifdef CONFIG_NO_IDLE_HZ extern ktime_t hrtimer_get_next_event(void); -#endif /* * A timer is active, when it is enqueued into the rbtree or the callback @@ -181,6 +276,15 @@ static inline int hrtimer_active(const struct hrtimer *timer) return timer->state != HRTIMER_STATE_INACTIVE; } +/* + * Helper function to check, whether the timer is on one of the queues + */ +static inline int hrtimer_is_queued(struct hrtimer *timer) +{ + return timer->state & + (HRTIMER_STATE_ENQUEUED | HRTIMER_STATE_PENDING); +} + /* Forward a hrtimer so it expires after now: */ extern unsigned long hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval); diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index 690113d..e5ea141 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -242,6 +242,9 @@ enum BLOCK_SOFTIRQ, TASKLET_SOFTIRQ, SCHED_SOFTIRQ, +#ifdef CONFIG_HIGH_RES_TIMERS + HRTIMER_SOFTIRQ, +#endif }; /* softirq mask and active fields moved to irq_cpustat_t in diff --git a/include/linux/ktime.h b/include/linux/ktime.h index 7444a63..c68c7ac 100644 --- a/include/linux/ktime.h +++ b/include/linux/ktime.h @@ -261,8 +261,7 @@ static inline s64 ktime_to_ns(const ktime_t kt) * idea of the (in)accuracy of timers. Timer values are rounded up to * this resolution values. */ -#define KTIME_REALTIME_RES (ktime_t){ .tv64 = TICK_NSEC } -#define KTIME_MONOTONIC_RES (ktime_t){ .tv64 = TICK_NSEC } +#define KTIME_LOW_RES (ktime_t){ .tv64 = TICK_NSEC } /* Get the monotonic time in timespec format: */ extern void ktime_get_ts(struct timespec *ts); diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index e04ef38..62aad8e 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -3,7 +3,7 @@ * * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de> * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar - * Copyright(C) 2006-2007 Timesys Corp., Thomas Gleixner <tglx@timesys.com> + * Copyright(C) 2006-2007 Timesys Corp., Thomas Gleixner * * High-resolution kernel timers * @@ -32,13 +32,17 @@ */ #include <linux/cpu.h> +#include <linux/irq.h> #include <linux/module.h> #include <linux/percpu.h> #include <linux/hrtimer.h> #include <linux/notifier.h> #include <linux/syscalls.h> +#include <linux/kallsyms.h> #include <linux/interrupt.h> #include <linux/tick.h> +#include <linux/seq_file.h> +#include <linux/err.h> #include <asm/uaccess.h> @@ -81,7 +85,7 @@ EXPORT_SYMBOL_GPL(ktime_get_real); * This ensures that we capture erroneous accesses to these clock ids * rather than moving them into the range of valid clock id's. */ -static DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) = +DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) = { .clock_base = @@ -89,12 +93,12 @@ static DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) = { .index = CLOCK_REALTIME, .get_time = &ktime_get_real, - .resolution = KTIME_REALTIME_RES, + .resolution = KTIME_LOW_RES, }, { .index = CLOCK_MONOTONIC, .get_time = &ktime_get, - .resolution = KTIME_MONOTONIC_RES, + .resolution = KTIME_LOW_RES, }, } }; @@ -151,14 +155,6 @@ static void hrtimer_get_softirq_time(struct hrtimer_cpu_base *base) } /* - * Helper function to check, whether the timer is on one of the queues - */ -static inline int hrtimer_is_queued(struct hrtimer *timer) -{ - return timer->state & HRTIMER_STATE_ENQUEUED; -} - -/* * Helper function to check, whether the timer is running the callback * function */ @@ -226,7 +222,7 @@ switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base) * completed. There is no conflict as we hold the lock until * the timer is enqueued. */ - if (unlikely(timer->state & HRTIMER_STATE_CALLBACK)) + if (unlikely(hrtimer_callback_running(timer))) return base; /* See the comment in lock_timer_base() */ @@ -250,7 +246,7 @@ lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags) return base; } -#define switch_hrtimer_base(t, b) (b) +# define switch_hrtimer_base(t, b) (b) #endif /* !CONFIG_SMP */ @@ -281,9 +277,6 @@ ktime_t ktime_add_ns(const ktime_t kt, u64 nsec) return ktime_add(kt, tmp); } - -#else /* CONFIG_KTIME_SCALAR */ - # endif /* !CONFIG_KTIME_SCALAR */ /* @@ -308,6 +301,290 @@ unsigned long ktime_divns(const ktime_t kt, s64 div) } #endif /* BITS_PER_LONG >= 64 */ +/* High resolution timer related functions */ +#ifdef CONFIG_HIGH_RES_TIMERS + +/* + * High resolution timer enabled ? + */ +static int hrtimer_hres_enabled __read_mostly = 1; + +/* + * Enable / Disable high resolution mode + */ +static int __init setup_hrtimer_hres(char *str) +{ + if (!strcmp(str, "off")) + hrtimer_hres_enabled = 0; + else if (!strcmp(str, "on")) + hrtimer_hres_enabled = 1; + else + return 0; + return 1; +} + +__setup("highres=", setup_hrtimer_hres); + +/* + * hrtimer_high_res_enabled - query, if the highres mode is enabled + */ +static inline int hrtimer_is_hres_enabled(void) +{ + return hrtimer_hres_enabled; +} + +/* + * Is the high resolution mode active ? + */ +static inline int hrtimer_hres_active(void) +{ + return __get_cpu_var(hrtimer_bases).hres_active; +} + +/* + * Reprogram the event source with checking both queues for the + * next event + * Called with interrupts disabled and base->lock held + */ +static void hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base) +{ + int i; + struct hrtimer_clock_base *base = cpu_base->clock_base; + ktime_t expires; + + cpu_base->expires_next.tv64 = KTIME_MAX; + + for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) { + struct hrtimer *timer; + + if (!base->first) + continue; + timer = rb_entry(base->first, struct hrtimer, node); + expires = ktime_sub(timer->expires, base->offset); + if (expires.tv64 < cpu_base->expires_next.tv64) + cpu_base->expires_next = expires; + } + + if (cpu_base->expires_next.tv64 != KTIME_MAX) + tick_program_event(cpu_base->expires_next, 1); +} + +/* + * Shared reprogramming for clock_realtime and clock_monotonic + * + * When a timer is enqueued and expires earlier than the already enqueued + * timers, we have to check, whether it expires earlier than the timer for + * which the clock event device was armed. + * + * Called with interrupts disabled and base->cpu_base.lock held + */ +static int hrtimer_reprogram(struct hrtimer *timer, + struct hrtimer_clock_base *base) +{ + ktime_t *expires_next = &__get_cpu_var(hrtimer_bases).expires_next; + ktime_t expires = ktime_sub(timer->expires, base->offset); + int res; + + /* + * When the callback is running, we do not reprogram the clock event + * device. The timer callback is either running on a different CPU or + * the callback is executed in the hrtimer_interupt context. The + * reprogramming is handled either by the softirq, which called the + * callback or at the end of the hrtimer_interrupt. + */ + if (hrtimer_callback_running(timer)) + return 0; + + if (expires.tv64 >= expires_next->tv64) + return 0; + + /* + * Clockevents returns -ETIME, when the event was in the past. + */ + res = tick_program_event(expires, 0); + if (!IS_ERR_VALUE(res)) + *expires_next = expires; + return res; +} + + +/* + * Retrigger next event is called after clock was set + * + * 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 } diff --git a/kernel/itimer.c b/kernel/itimer.c index 9cefe1d..4fc6c0c 100644 --- a/kernel/itimer.c +++ b/kernel/itimer.c @@ -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; } diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index 210f462..44318ca 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -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; diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig index 9ec54eb..f663511 100644 --- a/kernel/time/Kconfig +++ b/kernel/time/Kconfig @@ -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. + |
