Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[linux-2.6-block.git] / kernel / sched / core.c

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 956383844116ab456f8552abd4b5dcc00e09f347..3b31fc05a0f1e45be5985b860a5fde95ee969832 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3287,10 +3287,15 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
        struct task_struct *p;
 
        /*
-        * Optimization: we know that if all tasks are in
-        * the fair class we can call that function directly:
+        * Optimization: we know that if all tasks are in the fair class we can
+        * call that function directly, but only if the @prev task wasn't of a
+        * higher scheduling class, because otherwise those loose the
+        * opportunity to pull in more work from other CPUs.
         */
-       if (likely(rq->nr_running == rq->cfs.h_nr_running)) {
+       if (likely((prev->sched_class == &idle_sched_class ||
+                   prev->sched_class == &fair_sched_class) &&
+                  rq->nr_running == rq->cfs.h_nr_running)) {
+
                p = fair_sched_class.pick_next_task(rq, prev, rf);
                if (unlikely(p == RETRY_TASK))
                        goto again;