hrtimer: speedup hrtimer_enqueue

Speedup hrtimer_enqueue by evaluating the rbtree insertion result.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 4 deletions

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 065a8978662..eb1ddebd2c0 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -686,6 +686,7 @@ static void enqueue_hrtimer(struct hrtimer *timer,
         struct rb_node **link = &base->active.rb_node;
         struct rb_node *parent = NULL;
         struct hrtimer *entry;
+        int leftmost = 1;
 
         /*
          * Find the right place in the rbtree:
@@ -697,18 +698,19 @@ static void enqueue_hrtimer(struct hrtimer *timer,
                  * We dont care about collisions. Nodes with
                  * the same expiry time stay together.
                  */
-                if (timer->expires.tv64 < entry->expires.tv64)
+                if (timer->expires.tv64 < entry->expires.tv64) {
                         link = &(*link)->rb_left;
-                else
+                } else {
                         link = &(*link)->rb_right;
+                        leftmost = 0;
+                }
         }
 
         /*
          * 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 (leftmost) {
                 /*
                  * Reprogram the clock event device. When the timer is already
                  * expired hrtimer_enqueue_reprogram has either called the