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>

diff --git a/kernel/sched.c b/kernel/sched.c
index 3f5d529..9ccd91e 100644 (file)
--- 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