sched, rt: Provide means of disabling cross-cpu bandwidth sharing

Normally the RT bandwidth scheme will share bandwidth across the
entire root_domain. However sometimes its convenient to disable this
sharing for debug purposes. Provide a simple feature switch to this
end.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 4 insertions, 0 deletions

diff --git a/kernel/sched_features.h b/kernel/sched_features.h
index efa0a7b75dde..84802245abd2 100644
--- a/kernel/sched_features.h
+++ b/kernel/sched_features.h
@@ -67,3 +67,4 @@ SCHED_FEAT(NONTASK_POWER, 1)
 SCHED_FEAT(TTWU_QUEUE, 1)
 
 SCHED_FEAT(FORCE_SD_OVERLAP, 0)
+SCHED_FEAT(RT_RUNTIME_SHARE, 1)
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 056cbd2e2a27..583a1368afe6 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -560,6 +560,9 @@ static int balance_runtime(struct rt_rq *rt_rq)
 {
         int more = 0;
 
+        if (!sched_feat(RT_RUNTIME_SHARE))
+                return more;
+
         if (rt_rq->rt_time > rt_rq->rt_runtime) {
                 raw_spin_unlock(&rt_rq->rt_runtime_lock);
                 more = do_balance_runtime(rt_rq);