Pfair: add release master support.

1 files changed, 22 insertions, 3 deletions

diff --git a/litmus/sched_pfair.c b/litmus/sched_pfair.c
index 7168c77f0872..055ac623edb4 100644
--- a/litmus/sched_pfair.c
+++ b/litmus/sched_pfair.c
@@ -418,6 +418,11 @@ static void schedule_subtasks(struct pfair_cluster *cluster, quanta_t time)
         list_for_each(pos, &cluster->topology.cpus) {
                 cpu_state = from_cluster_list(pos);
                 retry = 1;
+#ifdef CONFIG_RELEASE_MASTER
+                /* skip release master */
+                if (cluster->pfair.release_master == cpu_id(cpu_state))
+                        continue;
+#endif
                 while (retry) {
                         if (pfair_higher_prio(__peek_ready(&cluster->pfair),
                                               cpu_state->linked))
@@ -588,6 +593,14 @@ static struct task_struct* pfair_schedule(struct task_struct * prev)
         int blocks;
         struct task_struct* next = NULL;
 
+#ifdef CONFIG_RELEASE_MASTER
+        /* Bail out early if we are the release master.
+         * The release master never schedules any real-time tasks.
+         */
+        if (cpu_cluster(state)->pfair.release_master == cpu_id(state))
+                return NULL;
+#endif
+
         raw_spin_lock(cpu_lock(state));
 
         if (is_realtime(prev) && get_rt_flags(prev) == RT_F_SLEEP)
@@ -628,12 +641,15 @@ static void pfair_task_new(struct task_struct * t, int on_rq, int running)
 
         prepare_release(t, cluster->pfair_time + 1);
 
+        t->rt_param.scheduled_on = NO_CPU;
+
         if (running) {
-                t->rt_param.scheduled_on = task_cpu(t);
+#ifdef CONFIG_RELEASE_MASTER
+                if (task_cpu(t) != cluster->pfair.release_master)
+#endif
+                        t->rt_param.scheduled_on = task_cpu(t);
                 __add_ready(&cluster->pfair, t);
         }
-        else
-                t->rt_param.scheduled_on = NO_CPU;
 
         check_preempt(t);
 
@@ -900,6 +916,9 @@ static long pfair_activate_plugin(void)
                 pfair_init_cluster(cluster);
                 cluster->pfair_time = now;
                 clust[i] = &cluster->topology;
+#ifdef CONFIG_RELEASE_MASTER
+                cluster->pfair.release_master = atomic_read(&release_master_cpu);
+#endif
         }
 
         for (i = 0; i < num_online_cpus(); i++)  {