[RFC PATCH 12/12 v2] Intercept RT scheduler

[Yuyang Du <yuyang.du@intel.com>]

We intercept load balancing to contain the load and load balancing in
the consolidated CPUs according to our consolidating mechanism.

In RT scheduler, we also skip pulling/selecting task to the idle
non-consolidated CPUs. This is pretty provocative.

Signed-off-by: Yuyang Du <yuyang.du@intel.com>
---
 kernel/sched/rt.c |   25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index bd2267a..f8141fb 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1217,6 +1217,9 @@ select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags)
 {
 	struct task_struct *curr;
 	struct rq *rq;
+#ifdef CONFIG_WORKLOAD_CONSOLIDATION
+	int do_find = 0;
+#endif
 
 	if (p->nr_cpus_allowed == 1)
 		goto out;
@@ -1230,6 +1233,11 @@ select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags)
 	rcu_read_lock();
 	curr = ACCESS_ONCE(rq->curr); /* unlocked access */
 
+#ifdef CONFIG_WORKLOAD_CONSOLIDATION
+	if (workload_consolidation_cpu_shielded(cpu))
+		do_find = 1;
+#endif
+
 	/*
 	 * If the current task on @p's runqueue is an RT task, then
 	 * try to see if we can wake this RT task up on another
@@ -1252,9 +1260,15 @@ select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags)
 	 * This test is optimistic, if we get it wrong the load-balancer
 	 * will have to sort it out.
 	 */
+#ifdef CONFIG_WORKLOAD_CONSOLIDATION
+	if (do_find || (curr && unlikely(rt_task(curr)) &&
+	    (curr->nr_cpus_allowed < 2 ||
+	     curr->prio <= p->prio))) {
+#else
 	if (curr && unlikely(rt_task(curr)) &&
 	    (curr->nr_cpus_allowed < 2 ||
 	     curr->prio <= p->prio)) {
+#endif
 		int target = find_lowest_rq(p);
 
 		if (target != -1)
@@ -1460,6 +1474,12 @@ static int find_lowest_rq(struct task_struct *task)
 	if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
 		return -1; /* No targets found */
 
+#ifdef CONFIG_WORKLOAD_CONSOLIDATION
+	workload_consolidation_nonshielded_mask(this_cpu, lowest_mask);
+	if (!cpumask_weight(lowest_mask))
+		return -1;
+#endif
+
 	/*
 	 * At this point we have built a mask of cpus representing the
 	 * lowest priority tasks in the system.  Now we want to elect
@@ -1687,6 +1707,11 @@ static int pull_rt_task(struct rq *this_rq)
 	if (likely(!rt_overloaded(this_rq)))
 		return 0;
 
+#ifdef CONFIG_WORKLOAD_CONSOLIDATION
+	if (workload_consolidation_cpu_shielded(this_cpu))
+		return 0;
+#endif
+
 	/*
 	 * Match the barrier from rt_set_overloaded; this guarantees that if we
 	 * see overloaded we must also see the rto_mask bit.
-- 
1.7.9.5