Merge branch 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  hrtimer: Eliminate needless reprogramming of clock events device

1 files changed, 35 insertions, 18 deletions

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index e5d98ce50f89..6d7020490f94 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -509,13 +509,14 @@ static inline int hrtimer_hres_active(void)
  * next event
  * Called with interrupts disabled and base->lock held
  */
-static void hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base)
+static void
+hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
 {
         int i;
         struct hrtimer_clock_base *base = cpu_base->clock_base;
-        ktime_t expires;
+        ktime_t expires, expires_next;
 
-        cpu_base->expires_next.tv64 = KTIME_MAX;
+        expires_next.tv64 = KTIME_MAX;
 
         for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
                 struct hrtimer *timer;
@@ -531,10 +532,15 @@ static void hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base)
                  */
                 if (expires.tv64 < 0)
                         expires.tv64 = 0;
-                if (expires.tv64 < cpu_base->expires_next.tv64)
-                        cpu_base->expires_next = expires;
+                if (expires.tv64 < expires_next.tv64)
+                        expires_next = expires;
         }
 
+        if (skip_equal && expires_next.tv64 == cpu_base->expires_next.tv64)
+                return;
+
+        cpu_base->expires_next.tv64 = expires_next.tv64;
+
         if (cpu_base->expires_next.tv64 != KTIME_MAX)
                 tick_program_event(cpu_base->expires_next, 1);
 }
@@ -617,7 +623,7 @@ static void retrigger_next_event(void *arg)
         base->clock_base[CLOCK_REALTIME].offset =
                 timespec_to_ktime(realtime_offset);
 
-        hrtimer_force_reprogram(base);
+        hrtimer_force_reprogram(base, 0);
         spin_unlock(&base->lock);
 }
 
@@ -730,7 +736,8 @@ static int hrtimer_switch_to_hres(void)
 static inline int hrtimer_hres_active(void) { return 0; }
 static inline int hrtimer_is_hres_enabled(void) { return 0; }
 static inline int hrtimer_switch_to_hres(void) { return 0; }
-static inline void hrtimer_force_reprogram(struct hrtimer_cpu_base *base) { }
+static inline void
+hrtimer_force_reprogram(struct hrtimer_cpu_base *base, int skip_equal) { }
 static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
                                             struct hrtimer_clock_base *base,
                                             int wakeup)
@@ -873,19 +880,29 @@ static void __remove_hrtimer(struct hrtimer *timer,
                              struct hrtimer_clock_base *base,
                              unsigned long newstate, int reprogram)
 {
-        if (timer->state & HRTIMER_STATE_ENQUEUED) {
-                /*
-                 * 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);
+        if (!(timer->state & HRTIMER_STATE_ENQUEUED))
+                goto out;
+
+        /*
+         * 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);
+#ifdef CONFIG_HIGH_RES_TIMERS
+                /* Reprogram the clock event device. if enabled */
+                if (reprogram && hrtimer_hres_active()) {
+                        ktime_t expires;
+
+                        expires = ktime_sub(hrtimer_get_expires(timer),
+                                            base->offset);
+                        if (base->cpu_base->expires_next.tv64 == expires.tv64)
+                                hrtimer_force_reprogram(base->cpu_base, 1);
                 }
-                rb_erase(&timer->node, &base->active);
+#endif
         }
+        rb_erase(&timer->node, &base->active);
+out:
         timer->state = newstate;
 }