From: Thomas Gleixner add the core bits of high-res timers support. the design makes use of the existing hrtimers subsystem which manages a per-CPU and per-clock tree of timers, and the clockevents framework, which provides a standard API to request programmable clock events from. The core code does not have to know about the clock details - it makes use of clockevents_set_next_event(). the code also provides dyntick functionality: it is implemented via a per-cpu sched_tick hrtimer that is set to HZ frequency, but which is reprogrammed to a longer timeout before going idle, and reprogrammed to HZ again once the CPU goes busy again. (If an non-timer IRQ hits the idle task then it will process jiffies before calling the IRQ code.) the impact to non-high-res architectures is intended to be minimal. Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar -- include/linux/hrtimer.h | 70 +++++ include/linux/interrupt.h | 5 include/linux/ktime.h | 3 kernel/hrtimer.c | 576 ++++++++++++++++++++++++++++++++++++++++++++-- kernel/itimer.c | 2 kernel/posix-timers.c | 2 kernel/time/Kconfig | 22 + kernel/timer.c | 1 8 files changed, 649 insertions(+), 32 deletions(-) Index: linux-2.6.18-mm2/include/linux/hrtimer.h =================================================================== --- linux-2.6.18-mm2.orig/include/linux/hrtimer.h 2006-09-30 01:41:17.000000000 +0200 +++ linux-2.6.18-mm2/include/linux/hrtimer.h 2006-09-30 01:41:18.000000000 +0200 @@ -17,6 +17,7 @@ #include #include +#include #include #include #include @@ -34,9 +35,17 @@ enum hrtimer_restart { HRTIMER_RESTART, }; +enum hrtimer_cb_mode { + HRTIMER_CB_SOFTIRQ, + HRTIMER_CB_IRQSAFE, + HRTIMER_CB_IRQSAFE_NO_RESTART, + HRTIMER_CB_IRQSAFE_NO_SOFTIRQ, +}; + #define HRTIMER_INACTIVE 0x00 #define HRTIMER_ACTIVE 0x01 #define HRTIMER_CALLBACK 0x02 +#define HRTIMER_PENDING 0x04 struct hrtimer_clock_base; @@ -49,6 +58,10 @@ struct hrtimer_clock_base; * @function: timer expiry callback function * @base: pointer to the timer base (per cpu and per clock) * + * @mode: high resolution timer feature to allow executing the + * callback in the hardirq context (wakeups) + * @cb_entry: list head to enqueue an expired timer into the callback list + * * The hrtimer structure must be initialized by init_hrtimer_#CLOCKTYPE() */ struct hrtimer { @@ -57,6 +70,10 @@ struct hrtimer { int (*function)(struct hrtimer *); struct hrtimer_clock_base *base; unsigned long state; +#ifdef CONFIG_HIGH_RES_TIMERS + int cb_mode; + struct list_head cb_entry; +#endif }; /** @@ -83,6 +100,9 @@ struct hrtimer_cpu_base; * @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; @@ -93,6 +113,12 @@ 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 @@ -108,17 +134,53 @@ 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; + unsigned long check_clocks; + struct list_head cb_pending; + struct hrtimer sched_timer; + struct pt_regs *sched_regs; + unsigned long events; +#endif }; +#ifdef CONFIG_HIGH_RES_TIMERS + +extern void hrtimer_clock_notify(void); +extern void clock_was_set(void); +extern void hrtimer_interrupt(struct pt_regs *regs); + +# define hrtimer_cb_get_time(t) (t)->base->get_time() +# define hrtimer_hres_active (__get_cpu_var(hrtimer_bases).hres_active) +/* + * 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 = CONFIG_HIGH_RES_RESOLUTION } +# 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) -#define hrtimer_clock_notify() do { } while (0) -extern ktime_t ktime_get(void); -extern ktime_t ktime_get_real(void); +# define clock_was_set() do { } while (0) +# define hrtimer_clock_notify() do { } while (0) + +# define hrtimer_cb_get_time(t) (t)->base->softirq_time +# define hrtimer_hres_active 0 + +#endif + + extern ktime_t ktime_get(void); + extern ktime_t ktime_get_real(void); /* Exported timer functions: */ Index: linux-2.6.18-mm2/include/linux/interrupt.h =================================================================== --- linux-2.6.18-mm2.orig/include/linux/interrupt.h 2006-09-30 01:41:11.000000000 +0200 +++ linux-2.6.18-mm2/include/linux/interrupt.h 2006-09-30 01:41:18.000000000 +0200 @@ -235,7 +235,10 @@ enum NET_TX_SOFTIRQ, NET_RX_SOFTIRQ, BLOCK_SOFTIRQ, - TASKLET_SOFTIRQ + TASKLET_SOFTIRQ, +#ifdef CONFIG_HIGH_RES_TIMERS + HRTIMER_SOFTIRQ, +#endif }; /* softirq mask and active fields moved to irq_cpustat_t in Index: linux-2.6.18-mm2/include/linux/ktime.h =================================================================== --- linux-2.6.18-mm2.orig/include/linux/ktime.h 2006-09-30 01:41:11.000000000 +0200 +++ linux-2.6.18-mm2/include/linux/ktime.h 2006-09-30 01:41:18.000000000 +0200 @@ -261,8 +261,7 @@ static inline u64 ktime_to_ns(const ktim * 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); Index: linux-2.6.18-mm2/kernel/hrtimer.c =================================================================== --- linux-2.6.18-mm2.orig/kernel/hrtimer.c 2006-09-30 01:41:17.000000000 +0200 +++ linux-2.6.18-mm2/kernel/hrtimer.c 2006-09-30 01:41:18.000000000 +0200 @@ -37,7 +37,11 @@ #include #include #include +#include #include +#include +#include +#include #include @@ -80,7 +84,7 @@ 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 = @@ -88,12 +92,12 @@ static DEFINE_PER_CPU(struct hrtimer_cpu { .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, }, } }; @@ -227,7 +231,7 @@ lock_hrtimer_base(const struct hrtimer * return base; } -#define switch_hrtimer_base(t, b) (b) +# define switch_hrtimer_base(t, b) (b) #endif /* !CONFIG_SMP */ @@ -258,9 +262,6 @@ ktime_t ktime_add_ns(const ktime_t kt, u return ktime_add(kt, tmp); } - -#else /* CONFIG_KTIME_SCALAR */ - # endif /* !CONFIG_KTIME_SCALAR */ /* @@ -288,11 +289,366 @@ static unsigned long ktime_divns(const k # define ktime_divns(kt, div) (unsigned long)((kt).tv64 / (div)) #endif /* BITS_PER_LONG >= 64 */ +/* High resolution timer related functions */ +#ifdef CONFIG_HIGH_RES_TIMERS + +static ktime_t last_jiffies_update; + +/* + * Reprogramm 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 = HRTIMER_MAX_CLOCK_BASES; i ; 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) + clockevents_set_next_event(cpu_base->expires_next, 1); +} + +/* + * Shared reprogramming for clock_realtime and clock_monotonic + * + * When a new expires first timer is enqueued, we have + * to check, whether it expires earlier than the timer + * for which the hrt time source 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; + + /* Callback running on another CPU ? */ + if (timer->state & HRTIMER_CALLBACK) + return 0; + + if (expires.tv64 >= expires_next->tv64) + return 0; + + res = clockevents_set_next_event(expires, 0); + if (!res) + *expires_next = expires; + return res; +} + + +/* + * Retrigger next event is called after clock was set + */ +static void retrigger_next_event(void *arg) +{ + struct hrtimer_cpu_base *base; + struct timespec realtime_offset; + unsigned long flags, seq; + + 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 = &per_cpu(hrtimer_bases, smp_processor_id()); + + /* Adjust CLOCK_REALTIME offset */ + spin_lock_irqsave(&base->lock, flags); + base->clock_base[CLOCK_REALTIME].offset = + timespec_to_ktime(realtime_offset); + + hrtimer_force_reprogram(base); + spin_unlock_irqrestore(&base->lock, flags); +} + +/* + * 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) +{ + preempt_disable(); + if (hrtimer_hres_active) { + retrigger_next_event(NULL); + + if (smp_call_function(retrigger_next_event, NULL, 1, 1)) + BUG(); + } + preempt_enable(); +} + +/** + * hrtimer_clock_notify - A clock source or a clock event has been installed + * + * Notify the per cpu softirqs to recheck the clock sources and events + */ +void hrtimer_clock_notify(void) +{ + int i; + + for (i = 0; i < NR_CPUS; i++) + set_bit(0, &per_cpu(hrtimer_bases, i).check_clocks); +} + + +static const ktime_t nsec_per_hz = { .tv64 = NSEC_PER_SEC / HZ }; + +/* + * We switched off the global tick source when switching to high resolution + * mode. Update jiffies64. + * + * Must be called with interrupts disabled ! + * + * FIXME: We need a mechanism to assign the update to a CPU. In principle this + * is not hard, but when dynamic ticks come into play it starts to be. We don't + * want to wake up a complete idle cpu just to update jiffies, so we need + * something more intellegent than a mere "do this only on CPUx". + */ +static void update_jiffies64(ktime_t now) +{ + ktime_t delta; + + write_seqlock(&xtime_lock); + + delta = ktime_sub(now, last_jiffies_update); + if (delta.tv64 >= nsec_per_hz.tv64) { + + unsigned long orun = 1; + + delta = ktime_sub(delta, nsec_per_hz); + last_jiffies_update = ktime_add(last_jiffies_update, + nsec_per_hz); + + /* Slow path for long timeouts */ + if (unlikely(delta.tv64 >= nsec_per_hz.tv64)) { + s64 incr = ktime_to_ns(nsec_per_hz); + orun = ktime_divns(delta, incr); + + last_jiffies_update = ktime_add_ns(last_jiffies_update, + incr * orun); + jiffies_64 += orun; + orun++; + } + do_timer(orun); + } + write_sequnlock(&xtime_lock); +} + +/* + * We rearm the timer until we get disabled by the idle code + */ +static int hrtimer_sched_tick(struct hrtimer *timer) +{ + unsigned long flags; + struct hrtimer_cpu_base *cpu_base = + container_of(timer, struct hrtimer_cpu_base, sched_timer); + + local_irq_save(flags); + /* + * Do not call, when we are not in irq context and have + * no valid regs pointer + */ + if (cpu_base->sched_regs) { + update_process_times(user_mode(cpu_base->sched_regs)); + profile_tick(CPU_PROFILING, cpu_base->sched_regs); + } + + hrtimer_forward(timer, hrtimer_cb_get_time(timer), nsec_per_hz); + local_irq_restore(flags); + + return HRTIMER_RESTART; +} + +/* + * A change in the clock source or clock events was detected. + * Check the clock source and the events, whether we can switch to + * high resolution mode or not. + * + * TODO: Handle the removal of clock sources / events + */ +static void hrtimer_check_clocks(void) +{ + struct hrtimer_cpu_base *base = &__get_cpu_var(hrtimer_bases); + unsigned long flags; + ktime_t now; + + if (!test_and_clear_bit(0, &base->check_clocks)) + return; + + if (!timekeeping_is_continuous()) + return; + + if (!clockevents_next_event_available()) + return; + + local_irq_save(flags); + + if (base->hres_active) { + local_irq_restore(flags); + return; + } + + now = ktime_get(); + if (clockevents_init_next_event()) { + 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; + + /* Did we start the jiffies update yet ? */ + if (last_jiffies_update.tv64 == 0) { + write_seqlock(&xtime_lock); + last_jiffies_update = now; + write_sequnlock(&xtime_lock); + } + + /* + * Emulate tick processing via per-CPU hrtimers: + */ + hrtimer_init(&base->sched_timer, CLOCK_MONOTONIC, HRTIMER_REL); + base->sched_timer.function = hrtimer_sched_tick; + base->sched_timer.cb_mode = HRTIMER_CB_IRQSAFE_NO_SOFTIRQ; + hrtimer_start(&base->sched_timer, nsec_per_hz, HRTIMER_REL); + + /* "Retrigger" the interrupt to get things going */ + retrigger_next_event(NULL); + local_irq_restore(flags); + printk(KERN_INFO "hrtimers: Switched to high resolution mode CPU %d\n", + smp_processor_id()); +} + +static inline int hrtimer_cb_pending(const struct hrtimer *timer) +{ + return !list_empty(&timer->cb_entry); +} + +static inline void hrtimer_remove_cb_pending(struct hrtimer *timer) +{ + list_del_init(&timer->cb_entry); +} + +static inline void hrtimer_add_cb_pending(struct hrtimer *timer, + struct hrtimer_clock_base *base) +{ + list_add_tail(&timer->cb_entry, &base->cpu_base->cb_pending); + timer->state = HRTIMER_PENDING; +} + +static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) +{ + base->expires_next.tv64 = KTIME_MAX; + set_bit(0, &base->check_clocks); + base->hres_active = 0; + INIT_LIST_HEAD(&base->cb_pending); +} + +static inline void hrtimer_init_timer_hres(struct hrtimer *timer) +{ + INIT_LIST_HEAD(&timer->cb_entry); +} + +static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer, + struct hrtimer_clock_base *base) +{ + /* + * When High resolution timers are active try to reprogram. Note, that + * in case the state has HRTIMER_CALLBACK set, no reprogramming and no + * expiry check happens. The timer gets enqueued into the rbtree and + * the reprogramming / expiry check is done in the hrtimer_interrupt or + * in the softirq. + */ + if (hrtimer_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 ! + */ + hrtimer_add_cb_pending(timer, base); + raise_softirq(HRTIMER_SOFTIRQ); + return 1; + default: + BUG(); + } + } + return 0; +} + +static inline void hrtimer_resume_jiffie_update(void) +{ + unsigned long flags; + ktime_t now = ktime_get(); + + write_seqlock_irqsave(&xtime_lock, flags); + last_jiffies_update = now; + write_sequnlock_irqrestore(&xtime_lock, flags); +} + +#else + +# define hrtimer_hres_active 0 +# define hrtimer_check_clocks() do { } while (0) +# define hrtimer_enqueue_reprogram(t,b) 0 +# define hrtimer_force_reprogram(b) do { } while (0) +# define hrtimer_cb_pending(t) 0 +# define hrtimer_remove_cb_pending(t) do { } while (0) +# define hrtimer_init_hres(c) do { } while (0) +# define hrtimer_init_timer_hres(t) do { } while (0) +# define hrtimer_resume_jiffie_update() do { } while (0) + +#endif /* CONFIG_HIGH_RES_TIMERS */ + /* * Timekeeping resumed notification */ void hrtimer_notify_resume(void) { + hrtimer_resume_jiffie_update(); clockevents_resume_events(); clock_was_set(); } @@ -380,13 +736,18 @@ static void enqueue_hrtimer(struct hrtim * 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) { + + if (hrtimer_enqueue_reprogram(timer, base)) + return; + + base->first = &timer->node; + } + rb_link_node(&timer->node, parent, link); rb_insert_color(&timer->node, &base->active); timer->state |= HRTIMER_ACTIVE; - - if (!base->first || timer->expires.tv64 < - rb_entry(base->first, struct hrtimer, node)->expires.tv64) - base->first = &timer->node; } /* @@ -396,15 +757,23 @@ static void enqueue_hrtimer(struct hrtim */ 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); + if (reprogram && hrtimer_hres_active) + hrtimer_force_reprogram(base->cpu_base); + } + rb_erase(&timer->node, &base->active); + } timer->state = newstate; } @@ -415,7 +784,11 @@ static inline int remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base) { if (hrtimer_active(timer)) { - __remove_hrtimer(timer, base, HRTIMER_INACTIVE); + /* + * Remove the timer and force reprogramming when high + * resolution mode is active + */ + __remove_hrtimer(timer, base, HRTIMER_INACTIVE, 1); return 1; } return 0; @@ -550,6 +923,13 @@ ktime_t hrtimer_get_next_event(void) unsigned long flags; int i; + /* + * In high-res mode we dont need to get the next high-res + * event on a tickless system: + */ + if (hrtimer_hres_active) + return mindelta; + spin_lock_irqsave(&cpu_base->lock, flags); for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) { @@ -592,6 +972,7 @@ void hrtimer_init(struct hrtimer *timer, clock_id = CLOCK_MONOTONIC; timer->base = &cpu_base->clock_base[clock_id]; + hrtimer_init_timer_hres(timer); } EXPORT_SYMBOL_GPL(hrtimer_init); @@ -614,6 +995,138 @@ int hrtimer_get_res(const clockid_t whic } EXPORT_SYMBOL_GPL(hrtimer_get_res); +#ifdef CONFIG_HIGH_RES_TIMERS + +/* + * High resolution timer interrupt + * Called with interrupts disabled + */ +void hrtimer_interrupt(struct pt_regs *regs) +{ + struct hrtimer_clock_base *base; + ktime_t expires_next, now; + int i, raise = 0, cpu = smp_processor_id(); + struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu); + + BUG_ON(!cpu_base->hres_active); + + /* Store the regs for an possible sched_timer callback */ + cpu_base->sched_regs = regs; + cpu_base->events++; + + retry: + now = ktime_get(); + + /* Check, if the jiffies need an update */ + update_jiffies64(now); + + 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_PENDING, 0); + hrtimer_add_cb_pending(timer, base); + raise = 1; + continue; + } + + __remove_hrtimer(timer, base, HRTIMER_CALLBACK, 0); + + if (timer->function(timer) != HRTIMER_NORESTART) { + BUG_ON(timer->state != HRTIMER_CALLBACK); + /* + * state == HRTIMER_CALLBACK prevents + * reprogramming. We do this when we break out + * of the loop ! + */ + enqueue_hrtimer(timer, base); + } + timer->state &= ~HRTIMER_CALLBACK; + } + spin_unlock(&cpu_base->lock); + base++; + } + + cpu_base->expires_next = expires_next; + + /* Reprogramming necessary ? */ + if (expires_next.tv64 != KTIME_MAX) { + if (clockevents_set_next_event(expires_next, 0)) + goto retry; + } + + /* Invalidate regs */ + cpu_base->sched_regs = NULL; + + /* Raise softirq ? */ + if (raise) + raise_softirq(HRTIMER_SOFTIRQ); +} + +static void run_hrtimer_softirq(struct softirq_action *h) +{ + struct hrtimer_cpu_base *cpu_base; + + cpu_base = &per_cpu(hrtimer_bases, smp_processor_id()); + + spin_lock_irq(&cpu_base->lock); + + while (!list_empty(&cpu_base->cb_pending)) { + struct hrtimer *timer; + int (*fn)(struct hrtimer *); + int restart; + + timer = list_entry(cpu_base->cb_pending.next, + struct hrtimer, cb_entry); + + fn = timer->function; + __remove_hrtimer(timer, timer->base, HRTIMER_CALLBACK, 0); + spin_unlock_irq(&cpu_base->lock); + + restart = fn(timer); + + spin_lock_irq(&cpu_base->lock); + + timer->state &= ~HRTIMER_CALLBACK; + if (restart == HRTIMER_RESTART) { + BUG_ON(hrtimer_active(timer)); + enqueue_hrtimer(timer, timer->base); + } else if (hrtimer_active(timer)) { + /* Timer was rearmed on another CPU: */ + 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: */ @@ -641,7 +1154,7 @@ static inline void run_hrtimer_queue(str break; fn = timer->function; - __remove_hrtimer(timer, base, HRTIMER_CALLBACK); + __remove_hrtimer(timer, base, HRTIMER_CALLBACK, 0); spin_unlock_irq(&cpu_base->lock); restart = fn(timer); @@ -659,12 +1172,21 @@ static inline void run_hrtimer_queue(str /* * 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; + hrtimer_check_clocks(); + + if (hrtimer_hres_active) + return; + hrtimer_get_softirq_time(cpu_base); for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) @@ -691,6 +1213,9 @@ void hrtimer_init_sleeper(struct hrtimer { 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) @@ -701,7 +1226,8 @@ static int __sched do_nanosleep(struct h 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_ABS; @@ -806,6 +1332,7 @@ static void __devinit init_hrtimers_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 @@ -819,7 +1346,7 @@ static void migrate_hrtimer_list(struct while ((node = rb_first(&old_base->active))) { timer = rb_entry(node, struct hrtimer, node); BUG_ON(timer->state & HRTIMER_CALLBACK); - __remove_hrtimer(timer, old_base, HRTIMER_INACTIVE); + __remove_hrtimer(timer, old_base, HRTIMER_INACTIVE, 0); timer->base = new_base; enqueue_hrtimer(timer, new_base); } @@ -884,5 +1411,8 @@ 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 } Index: linux-2.6.18-mm2/kernel/itimer.c =================================================================== --- linux-2.6.18-mm2.orig/kernel/itimer.c 2006-09-30 01:41:11.000000000 +0200 +++ linux-2.6.18-mm2/kernel/itimer.c 2006-09-30 01:41:18.000000000 +0200 @@ -136,7 +136,7 @@ int 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; } Index: linux-2.6.18-mm2/kernel/posix-timers.c =================================================================== --- linux-2.6.18-mm2.orig/kernel/posix-timers.c 2006-09-30 01:41:11.000000000 +0200 +++ linux-2.6.18-mm2/kernel/posix-timers.c 2006-09-30 01:41:18.000000000 +0200 @@ -356,7 +356,7 @@ static int posix_timer_fn(struct hrtimer 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; Index: linux-2.6.18-mm2/kernel/time/Kconfig =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ linux-2.6.18-mm2/kernel/time/Kconfig 2006-09-30 01:41:18.000000000 +0200 @@ -0,0 +1,22 @@ +# +# Timer subsystem related configuration options +# +config HIGH_RES_TIMERS + bool "High Resolution Timer Support" + depends on GENERIC_TIME + 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. + +config HIGH_RES_RESOLUTION + int "High Resolution Timer resolution (nanoseconds)" + depends on HIGH_RES_TIMERS + default 1000 + help + This sets the resolution in nanoseconds of the high resolution + timers. Too fine a resolution (small a number) will usually + not be observable due to normal system latencies. For an + 800 MHz processor about 10,000 (10 microseconds) is recommended as a + finest resolution. If you don't need that sort of resolution, + larger values may generate less overhead. Index: linux-2.6.18-mm2/kernel/timer.c =================================================================== --- linux-2.6.18-mm2.orig/kernel/timer.c 2006-09-30 01:41:16.000000000 +0200 +++ linux-2.6.18-mm2/kernel/timer.c 2006-09-30 01:41:18.000000000 +0200 @@ -1022,6 +1022,7 @@ static void update_wall_time(void) if (change_clocksource()) { clock->error = 0; clock->xtime_nsec = 0; + hrtimer_clock_notify(); clocksource_calculate_interval(clock, tick_nsec); } } -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/