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authorCarsten Emde <C.Emde@osadl.org>2010-02-15 22:30:34 +0100
committerThomas Gleixner <tglx@linutronix.de>2010-02-21 20:20:12 +0100
commit1954630a0637ad1ec2dcfe0324a36cd243f018ee (patch)
tree2203e64b007c232a5a7f8d302572eb2c025e6054
parent28bbb2398ebbeac1d4c1fd109938441842c8f89e (diff)
sched: Run task on same cpu if idle and allowed
The current RT balancer does not consider CPU topology and may wakeup a process to run on another CPU although it might run on the current. This patch adds a check and runs the new task on the current CPU, if it - is an RT task, - is allowed to run on the current CPU, and - current is not an RT task, Signed-off-by: Carsten Emde <C.Emde@osadl.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r--kernel/sched_rt.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 7a27ef6308c0..9de5f18b92bf 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -1030,6 +1030,17 @@ static int select_task_rq_rt(struct task_struct *p, int sd_flag, int flags)
}
/*
+ * If the new task is an RT task, current is not an RT task
+ * and the new one may run on the current CPU, run it here.
+ * This avoids sending reschedule IPIs across CPUs.
+ */
+ if (unlikely(rt_task(p)) && !rt_task(rq->curr)) {
+ int cpu = smp_processor_id();
+ if (cpumask_test_cpu(cpu, &p->cpus_allowed))
+ return cpu;
+ }
+
+ /*
* Otherwise, just let it ride on the affined RQ and the
* post-schedule router will push the preempted task away
*/