From e7693a362ec84bb5b6fd441d8a8b4b9d568a7a0c Mon Sep 17 00:00:00 2001 From: Gregory Haskins Date: Fri, 25 Jan 2008 21:08:09 +0100 Subject: 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 Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar --- kernel/sched_idletask.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'kernel/sched_idletask.c') diff --git a/kernel/sched_idletask.c b/kernel/sched_idletask.c index bf9c25c15b8..ca5374860ae 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, -- cgit v1.2.3-18-g5258