sched: add option whether CPU C-state is used to guide task placement

There are CPUs that don't have an obvious low power mode exit latency
penalty.  Add a new Kconfig CONFIG_SCHED_HMP_CSTATE_AWARE which controls
whether CPU C-state is used to guide task placement.

CRs-fixed: 1006303
Change-Id: Ie8dbab8e173c3a1842d922f4d1fbd8cc4221789c
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>

1 files changed, 47 insertions, 19 deletions

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index b6e638bdcd98..c0e35bc86b92 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3376,28 +3376,13 @@ next_best_cluster(struct sched_cluster *cluster, struct cpu_select_env *env,
 	return next;
 }
 
-static void update_cluster_stats(int cpu, struct cluster_cpu_stats *stats,
-					 struct cpu_select_env *env)
+#ifdef SCHED_HMP_CSTATE_AWARE
+static void __update_cluster_stats(int cpu, struct cluster_cpu_stats *stats,
+				   struct cpu_select_env *env, int cpu_cost)
 {
-	int cpu_cost, cpu_cstate;
+	int cpu_cstate;
 	int prev_cpu = env->prev_cpu;
 
-	cpu_cost = power_cost(cpu, task_load(env->p) +
-				cpu_cravg_sync(cpu, env->sync));
-	if (cpu_cost > stats->min_cost)
-		return;
-
-	if (cpu != prev_cpu && cpus_share_cache(prev_cpu, cpu)) {
-		if (stats->best_sibling_cpu_cost > cpu_cost ||
-		    (stats->best_sibling_cpu_cost == cpu_cost &&
-		     stats->best_sibling_cpu_load > env->cpu_load)) {
-
-			stats->best_sibling_cpu_cost = cpu_cost;
-			stats->best_sibling_cpu_load = env->cpu_load;
-			stats->best_sibling_cpu = cpu;
-		}
-	}
-
 	cpu_cstate = cpu_rq(cpu)->cstate;
 
 	if (env->need_idle) {
@@ -3452,6 +3437,49 @@ static void update_cluster_stats(int cpu, struct cluster_cpu_stats *stats,
 		stats->best_cpu = cpu;
 	}
 }
+#else /* SCHED_HMP_CSTATE_AWARE */
+static void __update_cluster_stats(int cpu, struct cluster_cpu_stats *stats,
+				   struct cpu_select_env *env, int cpu_cost)
+{
+	int prev_cpu = env->prev_cpu;
+
+	if (cpu != prev_cpu && cpus_share_cache(prev_cpu, cpu)) {
+		if (stats->best_sibling_cpu_cost > cpu_cost ||
+		    (stats->best_sibling_cpu_cost == cpu_cost &&
+		     stats->best_sibling_cpu_load > env->cpu_load)) {
+			stats->best_sibling_cpu_cost = cpu_cost;
+			stats->best_sibling_cpu_load = env->cpu_load;
+			stats->best_sibling_cpu = cpu;
+		}
+	}
+
+	if ((cpu_cost < stats->min_cost) ||
+	    ((stats->best_cpu != prev_cpu &&
+	      stats->min_load > env->cpu_load) || cpu == prev_cpu)) {
+		if (env->need_idle) {
+			if (idle_cpu(cpu)) {
+				stats->min_cost = cpu_cost;
+				stats->best_idle_cpu = cpu;
+			}
+		} else {
+			stats->min_cost = cpu_cost;
+			stats->min_load = env->cpu_load;
+			stats->best_cpu = cpu;
+		}
+	}
+}
+#endif
+
+static void update_cluster_stats(int cpu, struct cluster_cpu_stats *stats,
+					 struct cpu_select_env *env)
+{
+	int cpu_cost;
+
+	cpu_cost = power_cost(cpu, task_load(env->p) +
+				cpu_cravg_sync(cpu, env->sync));
+	if (cpu_cost <= stats->min_cost)
+		__update_cluster_stats(cpu, stats, env, cpu_cost);
+}
 
 static void find_best_cpu_in_cluster(struct sched_cluster *c,
 	 struct cpu_select_env *env, struct cluster_cpu_stats *stats)