sched/fair: Fix !CONFIG_SMP kernel cpufreq governor breakage

The following commit:

  34e2c555f3e1 ("cpufreq: Add mechanism for registering utilization update callbacks")

overlooked the fact that update_load_avg(), where CFS invokes cpufreq
utilization update callbacks, becomes an empty stub on UP kernels.

In consequence, if !CONFIG_SMP, cpufreq governors are never invoked
from CFS and they do not have a chance to evaluate CPU performace
levels and update them often enough.

Needless to say, things don't work as expected then.

Fix the problem by making the !CONFIG_SMP stub of update_load_avg()
invoke cpufreq update callbacks too.

Reported-by: Steve Muckle <[email protected]>
Tested-by: Steve Muckle <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>
Acked-by: Steve Muckle <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Linux PM list <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Srinivas Pandruvada <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Viresh Kumar <[email protected]>
Fixes: 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks)
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

1 files changed, 8 insertions, 1 deletions

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 0fe30e66aff1..40748dc8ea3e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3030,7 +3030,14 @@ static int idle_balance(struct rq *this_rq);
 
 #else /* CONFIG_SMP */
 
-static inline void update_load_avg(struct sched_entity *se, int update_tg) {}
+static inline void update_load_avg(struct sched_entity *se, int not_used)
+{
+	struct cfs_rq *cfs_rq = cfs_rq_of(se);
+	struct rq *rq = rq_of(cfs_rq);
+
+	cpufreq_trigger_update(rq_clock(rq));
+}
+
 static inline void
 enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
 static inline void