[RFCv7 PATCH 06/10] sched/fair: cpufreq_sched triggers for load balancing

[Steve Muckle]

From: Juri Lelli <juri.le...@arm.com>

As we don't trigger freq changes from {en,de}queue_task_fair() during load
balancing, we need to do explicitly so on load balancing paths.

[smuc...@linaro.org: move update_capacity_of calls so rq lock is held]

cc: Ingo Molnar <mi...@redhat.com>
cc: Peter Zijlstra <pet...@infradead.org>
Signed-off-by: Juri Lelli <juri.le...@arm.com>
Signed-off-by: Steve Muckle <smuc...@linaro.org>
---
 kernel/sched/fair.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index e7fab8f..5531513 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6107,6 +6107,10 @@ static void attach_one_task(struct rq *rq, struct 
task_struct *p)
 {
        raw_spin_lock(&rq->lock);
        attach_task(rq, p);
+       /*
+        * We want to potentially raise target_cpu's OPP.
+        */
+       update_capacity_of(cpu_of(rq));
        raw_spin_unlock(&rq->lock);
 }
 
@@ -6128,6 +6132,11 @@ static void attach_tasks(struct lb_env *env)
                attach_task(env->dst_rq, p);
        }
 
+       /*
+        * We want to potentially raise env.dst_cpu's OPP.
+        */
+       update_capacity_of(env->dst_cpu);
+
        raw_spin_unlock(&env->dst_rq->lock);
 }
 
@@ -7267,6 +7276,11 @@ more_balance:
                 * ld_moved     - cumulative load moved across iterations
                 */
                cur_ld_moved = detach_tasks(&env);
+               /*
+                * We want to potentially lower env.src_cpu's OPP.
+                */
+               if (cur_ld_moved)
+                       update_capacity_of(env.src_cpu);
 
                /*
                 * We've detached some tasks from busiest_rq. Every
@@ -7631,8 +7645,13 @@ static int active_load_balance_cpu_stop(void *data)
                schedstat_inc(sd, alb_count);
 
                p = detach_one_task(&env);
-               if (p)
+               if (p) {
                        schedstat_inc(sd, alb_pushed);
+                       /*
+                        * We want to potentially lower env.src_cpu's OPP.
+                        */
+                       update_capacity_of(env.src_cpu);
+               }
                else
                        schedstat_inc(sd, alb_failed);
        }
-- 
2.4.10