[COMMON] sched: ems: Change how to select ontime target CPU

Change-Id: I2e36d26feb1858de6f8a912a9365627927f4e9f3
Signed-off-by: Daeyeong Lee <daeyeong.lee@samsung.com>

diff --git a/kernel/sched/ems/ontime.c b/kernel/sched/ems/ontime.c
index c48b7c8bdf078f57cca6919edbe9d74adbfbdbf2..37f2cf1f9ba5c5e12ba161a1874b78173c61cd86 100644 (file)
--- a/kernel/sched/ems/ontime.c
+++ b/kernel/sched/ems/ontime.c
@@ -167,17 +167,22 @@ static int
 ontime_select_target_cpu(struct task_struct *p, struct cpumask *fit_cpus)
 {
        struct cpumask candidates;
-       int cpu, min_energy_cpu = -1;
+       int cpu, energy_cpu = -1;
        int candidate_count = 0;
 
+       rcu_read_lock();
+
        cpumask_clear(&candidates);
 
        /*
         * First) Find min_util_cpu for each coregroup in fit cpus and candidate it.
         */
        for_each_cpu(cpu, fit_cpus) {
-               int i, min_util_cpu = -1;
-               unsigned long coverage_util, min_util = ULONG_MAX;
+               int i;
+               int best_cpu = -1, backup_cpu = -1;
+               unsigned int min_exit_latency = UINT_MAX;
+               unsigned long min_util = ULONG_MAX;
+               unsigned long coverage_util;
 
                if (cpu != cpumask_first(cpu_coregroup_mask(cpu)))
                        continue;
@@ -185,7 +190,6 @@ ontime_select_target_cpu(struct task_struct *p, struct cpumask *fit_cpus)
                coverage_util = capacity_orig_of(cpu) * get_coverage_ratio(cpu);
 
                for_each_cpu_and(i, cpu_coregroup_mask(cpu), cpu_active_mask) {
-                       unsigned long new_util;
 
                        if (!cpumask_test_cpu(i, tsk_cpus_allowed(p)))
                                continue;
@@ -193,23 +197,43 @@ ontime_select_target_cpu(struct task_struct *p, struct cpumask *fit_cpus)
                        if (cpu_rq(i)->ontime_migrating)
                                continue;
 
-                       new_util = task_util(p) + cpu_util_wake(i, p);
-
-                       if (new_util * 100 >= coverage_util)
-                               continue;
-
-                       if (new_util < min_util) {
-                               min_util = new_util;
-                               min_util_cpu = i;
+                       if (idle_cpu(i)) {
+                               /* 1. Find shallowest idle_cpu */
+                               struct cpuidle_state *idle = idle_get_state(cpu_rq(cpu));
+
+                               if (!idle) {
+                                       best_cpu = i;
+                                       break;
+                               }
+
+                               if (idle->exit_latency < min_exit_latency) {
+                                       min_exit_latency = idle->exit_latency;
+                                       best_cpu = i;
+                               }
+                       } else {
+                               /* 2. Find cpu that have to spare */
+                               unsigned long new_util = task_util(p) + cpu_util_wake(i, p);
+
+                               if (new_util * 100 >= coverage_util)
+                                       continue;
+
+                               if (new_util < min_util) {
+                                       min_util = new_util;
+                                       backup_cpu = i;
+                               }
                        }
                }
-
-               if (cpu_selected(min_util_cpu)) {
-                       cpumask_set_cpu(min_util_cpu, &candidates);
+               if (cpu_selected(best_cpu)) {
+                       cpumask_set_cpu(best_cpu, &candidates);
+                       candidate_count++;
+               } else if (cpu_selected(backup_cpu)) {
+                       cpumask_set_cpu(backup_cpu, &candidates);
                        candidate_count++;
                }
        }
 
+       rcu_read_unlock();
+
        /*
         * Second) Find min_energy_cpu among the candidates and return it.
         */
@@ -225,17 +249,17 @@ ontime_select_target_cpu(struct task_struct *p, struct cpumask *fit_cpus)
 
                        if (min_energy > new_energy) {
                                min_energy = new_energy;
-                               min_energy_cpu = cpu;
+                               energy_cpu = cpu;
                        }
                }
        } else if (candidate_count == 1) {
                /*
                 * If there is just one candidate, this will be min_energy_cpu.
                 */
-               min_energy_cpu = cpumask_first(&candidates);
+               energy_cpu = cpumask_first(&candidates);
        }
 
-       return min_energy_cpu;
+       return energy_cpu;
 }
 
 extern struct sched_entity *__pick_next_entity(struct sched_entity *se);