sched: optimize task_new_fair()

due to the fact that we no longer keep the 'current' within the tree, dequeue/enqueue_entity() is useless for the 'current' in task_new_fair(). We are about to reschedule and sched_class->put_prev_task() will put the 'current' back into the tree, based on its new key. text data bss dec hex filename 24388 2734 20 27142 6a06 sched.o.before 24341 2734 20 27095 69d7 sched.o.after Signed-off-by: Dmitry Adamushko <[email protected]> Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Peter Zijlstra <[email protected]> Reviewed-by: Thomas Gleixner <[email protected]>
ashr · Oct 15, 2007 · 87fefa3 · 87fefa3
1 parent 75d4ef1
commit 87fefa3
Showing 1 changed file with 4 additions and 3 deletions.
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
@@ -972,10 +972,11 @@ static void task_new_fair(struct rq *rq, struct task_struct *p)
 
 	if (sysctl_sched_child_runs_first &&
 			curr->vruntime < se->vruntime) {
-
-		dequeue_entity(cfs_rq, curr, 0);
+		/*
+ 		 * Upon rescheduling, sched_class::put_prev_task() will place
+ 		 * 'current' within the tree based on its new key value.
+ 		 */
 		swap(curr->vruntime, se->vruntime);
-		enqueue_entity(cfs_rq, curr, 0);
 	}
 
 	update_stats_enqueue(cfs_rq, se);