aosp-ack-5.4-find_energy_efficient_cpu.diff

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 54b5dd8dd46d..3cc3e76de129 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6457,8 +6457,11 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu, int sy
 			if (cpu_cap < uclamp_task_util(p))
 				continue;
 
+			if (prefer_idle)
+				goto find_best_idle;
+
 			/* Always use prev_cpu as a candidate. */
-			if (!prefer_idle && cpu == prev_cpu) {
+			if (cpu == prev_cpu) {
 				prev_energy = compute_energy(p, prev_cpu, head);
 				best_energy = min(best_energy, prev_energy);
 				continue;
@@ -6474,8 +6477,9 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu, int sy
 				max_spare_cap_cpu = cpu;
 			}
 
-			if (!prefer_idle)
-				continue;
+		find_best_idle:
+
+			/* Add comments here to explain the policy */
 
 			if (idle_cpu(cpu)) {
 				cpu_cap = capacity_orig_of(cpu);
@@ -6484,22 +6488,30 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu, int sy
 				if (!boosted && cpu_cap > target_cap)
 					continue;
 				idle = idle_get_state(cpu_rq(cpu));
-				if (idle && idle->exit_latency > min_exit_lat &&
-						cpu_cap == target_cap)
-					continue;
-
-				if (idle)
+				if (idle) {
+					if (idle->exit_latency > min_exit_lat &&
+					    cpu_cap == target_cap) {
+						continue;
+					}
 					min_exit_lat = idle->exit_latency;
+				}
 				target_cap = cpu_cap;
 				best_idle_cpu = cpu;
-			} else if (spare_cap > highest_spare_cap) {
+				continue;
+			}
+
+			spare_cap = cpu_cap - util;
+			if (spare_cap > highest_spare_cap) {
 				highest_spare_cap = spare_cap;
 				highest_spare_cap_cpu = cpu;
 			}
 		}
 
+		if (prefer_idle)
+			continue;
+
 		/* Evaluate the energy impact of using this CPU. */
-		if (!prefer_idle && max_spare_cap_cpu >= 0) {
+		if (max_spare_cap_cpu >= 0) {
 			cur_energy = compute_energy(p, max_spare_cap_cpu, head);
 			if (cur_energy < best_energy) {
 				best_energy = cur_energy;