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authorGregory Haskins <ghaskins@novell.com>2008-01-25 21:08:09 +0100
committerIngo Molnar <mingo@elte.hu>2008-01-25 21:08:09 +0100
commite7693a362ec84bb5b6fd441d8a8b4b9d568a7a0c (patch)
tree078940540641a59aaf199695bfc6de3f062a987b /kernel/sched_idletask.c
parentsched: clean up this_rq use in kernel/sched_rt.c (diff)
downloadlinux-e7693a362ec84bb5b6fd441d8a8b4b9d568a7a0c.tar.xz
linux-e7693a362ec84bb5b6fd441d8a8b4b9d568a7a0c.zip
sched: de-SCHED_OTHER-ize the RT path
The current wake-up code path tries to determine if it can optimize the wake-up to "this_cpu" by computing load calculations. The problem is that these calculations are only relevant to SCHED_OTHER tasks where load is king. For RT tasks, priority is king. So the load calculation is completely wasted bandwidth. Therefore, we create a new sched_class interface to help with pre-wakeup routing decisions and move the load calculation as a function of CFS task's class. Signed-off-by: Gregory Haskins <ghaskins@novell.com> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched_idletask.c')
-rw-r--r--kernel/sched_idletask.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/kernel/sched_idletask.c b/kernel/sched_idletask.c
index bf9c25c15b8b..ca5374860aef 100644
--- a/kernel/sched_idletask.c
+++ b/kernel/sched_idletask.c
@@ -5,6 +5,12 @@
* handled in sched_fair.c)
*/
+#ifdef CONFIG_SMP
+static int select_task_rq_idle(struct task_struct *p, int sync)
+{
+ return task_cpu(p); /* IDLE tasks as never migrated */
+}
+#endif /* CONFIG_SMP */
/*
* Idle tasks are unconditionally rescheduled:
*/
@@ -72,6 +78,9 @@ const struct sched_class idle_sched_class = {
/* dequeue is not valid, we print a debug message there: */
.dequeue_task = dequeue_task_idle,
+#ifdef CONFIG_SMP
+ .select_task_rq = select_task_rq_idle,
+#endif /* CONFIG_SMP */
.check_preempt_curr = check_preempt_curr_idle,