sched: rt throttling vs no_hz

We need to teach no_hz about the rt throttling because its tick driven.

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

1 files changed, 22 insertions, 1 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 5ea2c533b432..22712b2e058a 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -442,6 +442,7 @@ struct rq {
         struct cfs_rq cfs;
         struct rt_rq rt;
         u64 rt_period_expire;
+        int rt_throttled;
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
         /* list of leaf cfs_rq on this cpu: */
@@ -594,6 +595,23 @@ static void update_rq_clock(struct rq *rq)
 #define task_rq(p)              cpu_rq(task_cpu(p))
 #define cpu_curr(cpu)           (cpu_rq(cpu)->curr)
 
+unsigned long rt_needs_cpu(int cpu)
+{
+        struct rq *rq = cpu_rq(cpu);
+        u64 delta;
+
+        if (!rq->rt_throttled)
+                return 0;
+
+        if (rq->clock > rq->rt_period_expire)
+                return 1;
+
+        delta = rq->rt_period_expire - rq->clock;
+        do_div(delta, NSEC_PER_SEC / HZ);
+
+        return (unsigned long)delta;
+}
+
 /*
  * Tunables that become constants when CONFIG_SCHED_DEBUG is off:
  */
@@ -7102,9 +7120,11 @@ static void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq)
         /* delimiter for bitsearch: */
         __set_bit(MAX_RT_PRIO, array->bitmap);
 
+#if defined CONFIG_SMP || defined CONFIG_FAIR_GROUP_SCHED
+        rt_rq->highest_prio = MAX_RT_PRIO;
+#endif
 #ifdef CONFIG_SMP
         rt_rq->rt_nr_migratory = 0;
-        rt_rq->highest_prio = MAX_RT_PRIO;
         rt_rq->overloaded = 0;
 #endif
 
@@ -7191,6 +7211,7 @@ void __init sched_init(void)
                                 &per_cpu(init_sched_rt_entity, i), i, 1);
 #endif
                 rq->rt_period_expire = 0;
+                rq->rt_throttled = 0;
 
                 for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
                         rq->cpu_load[j] = 0;