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>

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 065a897..eb1ddeb 100644 (file)
--- 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