[RFC PATCH 04/12 v2] CPU ConCurrency tracking

[Yuyang Du]

CC can only be modified when enqueue and dequeue the CPU rq. And we also
track it in scheduler tick and idle enter/exit in case we may not have
enqueue and dequeue for a long time.

Therefore, we track CC in and only in these four points:

1. dequeue
2. enqueue
3. scheduler tick
4. idle enter and exit

TODO: use existing load tracking framework

Signed-off-by: Yuyang Du <yuyang.du@xxxxxxxxx>
---
 kernel/sched/core.c |    3 +++
 kernel/sched/fair.c |    2 ++
 2 files changed, 5 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 7958a47..0236455 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -767,6 +767,7 @@ static void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
 	update_rq_clock(rq);
 	sched_info_queued(rq, p);
 	p->sched_class->enqueue_task(rq, p, flags);
+	update_cpu_concurrency(rq);
 }
 
 static void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
@@ -774,6 +775,7 @@ static void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
 	update_rq_clock(rq);
 	sched_info_dequeued(rq, p);
 	p->sched_class->dequeue_task(rq, p, flags);
+	update_cpu_concurrency(rq);
 }
 
 void activate_task(struct rq *rq, struct task_struct *p, int flags)
@@ -2428,6 +2430,7 @@ void scheduler_tick(void)
 	update_rq_clock(rq);
 	curr->sched_class->task_tick(rq, curr, 0);
 	update_cpu_load_active(rq);
+	update_cpu_concurrency(rq);
 	raw_spin_unlock(&rq->lock);
 
 	perf_event_task_tick();
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7570dd9..e7153ff 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2563,6 +2563,7 @@ static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq,
 void idle_enter_fair(struct rq *this_rq)
 {
 	update_rq_runnable_avg(this_rq, 1);
+	update_cpu_concurrency(this_rq);
 }
 
 /*
@@ -2573,6 +2574,7 @@ void idle_enter_fair(struct rq *this_rq)
 void idle_exit_fair(struct rq *this_rq)
 {
 	update_rq_runnable_avg(this_rq, 0);
+	update_cpu_concurrency(this_rq);
 }
 
 static int idle_balance(struct rq *this_rq);
-- 
1.7.9.5

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