sched, cpuidle: Track cpuidle state index in the scheduler

The idle-state of each cpu is currently pointed to by rq->idle_state but
there isn't any information in the struct cpuidle_state that can used to
look up the idle-state energy model data stored in struct
sched_group_energy. For this purpose is necessary to store the idle
state index as well. Ideally, the idle-state data should be unified.

cc: Ingo Molnar <mingo@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>

Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>

2 files changed, 29 insertions, 0 deletions

diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 594275ed2620..f49f27cb554c 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -108,12 +108,20 @@ static int call_cpuidle(struct cpuidle_driver *drv, struct cpuidle_device *dev,
 		return -EBUSY;
 	}
 
+       /* Take note of the planned idle state. */
+        idle_set_state(this_rq(), &drv->states[next_state]);
+        idle_set_state_idx(this_rq(), next_state);
+
 	/*
 	 * Enter the idle state previously returned by the governor decision.
 	 * This function will block until an interrupt occurs and will take
 	 * care of re-enabling the local interrupts
 	 */
 	return cpuidle_enter(drv, dev, next_state);
+
+	idle_set_state(this_rq(), NULL);
+	idle_set_state_idx(this_rq(), -1);
+
 }
 
 /**
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index fcbe1a4a8dba..6a78f5c7aaba 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -703,6 +703,7 @@ struct rq {
 #ifdef CONFIG_CPU_IDLE
 	/* Must be inspected within a rcu lock section */
 	struct cpuidle_state *idle_state;
+	int idle_state_idx;
 #endif
 };
 
@@ -1332,6 +1333,17 @@ static inline struct cpuidle_state *idle_get_state(struct rq *rq)
 	WARN_ON(!rcu_read_lock_held());
 	return rq->idle_state;
 }
+
+static inline void idle_set_state_idx(struct rq *rq, int idle_state_idx)
+{
+	rq->idle_state_idx = idle_state_idx;
+}
+
+static inline int idle_get_state_idx(struct rq *rq)
+{
+	WARN_ON(!rcu_read_lock_held());
+	return rq->idle_state_idx;
+}
 #else
 static inline void idle_set_state(struct rq *rq,
 				  struct cpuidle_state *idle_state)
@@ -1342,6 +1354,15 @@ static inline struct cpuidle_state *idle_get_state(struct rq *rq)
 {
 	return NULL;
 }
+
+static inline void idle_set_state_idx(struct rq *rq, int idle_state_idx)
+{
+}
+
+static inline int idle_get_state_idx(struct rq *rq)
+{
+	return -1;
+}
 #endif
 
 extern void sysrq_sched_debug_show(void);