sched: rt: fix SMP bandwidth balancing for throttled groups
Now we exceed the runtime and get throttled - the period rollover tick
will subtract the cpu quota from the runtime and check if we're below
quota. However with this cpu having a very small portion of the runtime
it will not refresh as fast as it should.
Therefore, also rebalance the runtime when we're throttled.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "Daniel K." <dk@uw.no>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 2e0ccdc..87b2e3b 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -228,6 +228,28 @@
#endif
+#ifdef CONFIG_SMP
+static int do_balance_runtime(struct rt_rq *rt_rq);
+
+static int balance_runtime(struct rt_rq *rt_rq)
+{
+ int more = 0;
+
+ if (rt_rq->rt_time > rt_rq->rt_runtime) {
+ spin_unlock(&rt_rq->rt_runtime_lock);
+ more = do_balance_runtime(rt_rq);
+ spin_lock(&rt_rq->rt_runtime_lock);
+ }
+
+ return more;
+}
+#else
+static inline int balance_runtime(struct rt_rq *rt_rq)
+{
+ return 0;
+}
+#endif
+
static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
{
int i, idle = 1;
@@ -247,6 +269,8 @@
u64 runtime;
spin_lock(&rt_rq->rt_runtime_lock);
+ if (rt_rq->rt_throttled)
+ balance_runtime(rt_rq);
runtime = rt_rq->rt_runtime;
rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
@@ -267,7 +291,7 @@
}
#ifdef CONFIG_SMP
-static int balance_runtime(struct rt_rq *rt_rq)
+static int do_balance_runtime(struct rt_rq *rt_rq)
{
struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
struct root_domain *rd = cpu_rq(smp_processor_id())->rd;
@@ -428,17 +452,10 @@
if (sched_rt_runtime(rt_rq) >= sched_rt_period(rt_rq))
return 0;
-#ifdef CONFIG_SMP
- if (rt_rq->rt_time > runtime) {
- spin_unlock(&rt_rq->rt_runtime_lock);
- balance_runtime(rt_rq);
- spin_lock(&rt_rq->rt_runtime_lock);
-
- runtime = sched_rt_runtime(rt_rq);
- if (runtime == RUNTIME_INF)
- return 0;
- }
-#endif
+ balance_runtime(rt_rq);
+ runtime = sched_rt_runtime(rt_rq);
+ if (runtime == RUNTIME_INF)
+ return 0;
if (rt_rq->rt_time > runtime) {
rt_rq->rt_throttled = 1;
