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[PATCH] hrtimers: add high resolution timer support

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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 2007-02-16 01:28:11 -08:00 committed by Linus Torvalds
parent d40891e75f
commit 54cdfdb47f
8 changed files with 650 additions and 58 deletions
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4
Documentation/kernel-parameters.txt
View File

@ -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.

116
include/linux/hrtimer.h
View File

@ -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);

3
include/linux/interrupt.h
View File

@ -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

3
include/linux/ktime.h
View File

@ -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);

568
kernel/hrtimer.c
View File

@ -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,
},
}
};
@ -150,14 +154,6 @@ static void hrtimer_get_softirq_time(struct hrtimer_cpu_base *base)
ktime_add(xtim, tomono);
}
/*
* 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
}

2
kernel/itimer.c
View File

@ -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;
}

2
kernel/posix-timers.c
View File

@ -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;

10
kernel/time/Kconfig
View File

@ -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.