sched: optimize activate_task()

optimize activate_task() by removing update_rq_clock() from it.
(and add update_rq_clock() to all callsites of activate_task() that
did not have it before.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 9 insertions, 10 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 3f5d52949990..9ccd91e5b65b 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -910,8 +910,6 @@ static int effective_prio(struct task_struct *p)
  */
 static void activate_task(struct rq *rq, struct task_struct *p, int wakeup)
 {
-        update_rq_clock(rq);
-
         if (p->state == TASK_UNINTERRUPTIBLE)
                 rq->nr_uninterruptible--;
 
@@ -1510,6 +1508,7 @@ out_set_cpu:
 
 out_activate:
 #endif /* CONFIG_SMP */
+        update_rq_clock(rq);
         activate_task(rq, p, 1);
         /*
          * Sync wakeups (i.e. those types of wakeups where the waker
@@ -2117,6 +2116,7 @@ static void pull_task(struct rq *src_rq, struct task_struct *p,
         update_rq_clock(src_rq);
         deactivate_task(src_rq, p, 0);
         set_task_cpu(p, this_cpu);
+        __update_rq_clock(this_rq);
         activate_task(this_rq, p, 0);
         /*
          * Note that idle threads have a prio of MAX_PRIO, for this test
@@ -4207,11 +4207,10 @@ recheck:
                 spin_unlock_irqrestore(&p->pi_lock, flags);
                 goto recheck;
         }
+        update_rq_clock(rq);
         on_rq = p->se.on_rq;
-        if (on_rq) {
-                update_rq_clock(rq);
+        if (on_rq)
                 deactivate_task(rq, p, 0);
-        }
         oldprio = p->prio;
         __setscheduler(rq, p, policy, param->sched_priority);
         if (on_rq) {
@@ -4969,6 +4968,7 @@ static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
         }
         set_task_cpu(p, dest_cpu);
         if (on_rq) {
+                update_rq_clock(rq_dest);
                 activate_task(rq_dest, p, 0);
                 check_preempt_curr(rq_dest, p);
         }
@@ -6623,14 +6623,13 @@ void normalize_rt_tasks(void)
                         goto out_unlock;
 #endif
 
+                update_rq_clock(rq);
                 on_rq = p->se.on_rq;
-                if (on_rq) {
-                        update_rq_clock(task_rq(p));
-                        deactivate_task(task_rq(p), p, 0);
-                }
+                if (on_rq)
+                        deactivate_task(rq, p, 0);
                 __setscheduler(rq, p, SCHED_NORMAL, 0);
                 if (on_rq) {
-                        activate_task(task_rq(p), p, 0);
+                        activate_task(rq, p, 0);
                         resched_task(rq->curr);
                 }
 #ifdef CONFIG_SMP