sched: use a 2-d bitmap for searching lowest-pri CPU

[linux-2.6-omap-h63xx.git] / kernel / sched_rt.c

diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index fefed39fafd8fa6b5088ea8c4179c01ddd7debab..44b06d75416ea23f345e54fc682f2665e3be0040 100644 (file)
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -391,8 +391,11 @@ void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
        WARN_ON(!rt_prio(rt_se_prio(rt_se)));
        rt_rq->rt_nr_running++;
 #if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
-       if (rt_se_prio(rt_se) < rt_rq->highest_prio)
+       if (rt_se_prio(rt_se) < rt_rq->highest_prio) {
+               struct rq *rq = rq_of_rt_rq(rt_rq);
                rt_rq->highest_prio = rt_se_prio(rt_se);
+               cpupri_set(&rq->rd->cpupri, rq->cpu, rt_se_prio(rt_se));
+       }
 #endif
 #ifdef CONFIG_SMP
        if (rt_se->nr_cpus_allowed > 1) {
@@ -416,6 +419,10 @@ void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 static inline
 void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 {
+#ifdef CONFIG_SMP
+       int highest_prio = rt_rq->highest_prio;
+#endif
+
        WARN_ON(!rt_prio(rt_se_prio(rt_se)));
        WARN_ON(!rt_rq->rt_nr_running);
        rt_rq->rt_nr_running--;
@@ -439,6 +446,11 @@ void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
                rq->rt.rt_nr_migratory--;
        }
 
+       if (rt_rq->highest_prio != highest_prio) {
+               struct rq *rq = rq_of_rt_rq(rt_rq);
+               cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio);
+       }
+
        update_rt_migration(rq_of_rt_rq(rt_rq));
 #endif /* CONFIG_SMP */
 #ifdef CONFIG_RT_GROUP_SCHED
@@ -763,73 +775,6 @@ static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu)
 
 static DEFINE_PER_CPU(cpumask_t, local_cpu_mask);
 
-static int find_lowest_cpus(struct task_struct *task, cpumask_t *lowest_mask)
-{
-       int       lowest_prio = -1;
-       int       lowest_cpu  = -1;
-       int       count       = 0;
-       int       cpu;
-
-       cpus_and(*lowest_mask, task_rq(task)->rd->online, task->cpus_allowed);
-
-       /*
-        * Scan each rq for the lowest prio.
-        */
-       for_each_cpu_mask(cpu, *lowest_mask) {
-               struct rq *rq = cpu_rq(cpu);
-
-               /* We look for lowest RT prio or non-rt CPU */
-               if (rq->rt.highest_prio >= MAX_RT_PRIO) {
-                       /*
-                        * if we already found a low RT queue
-                        * and now we found this non-rt queue
-                        * clear the mask and set our bit.
-                        * Otherwise just return the queue as is
-                        * and the count==1 will cause the algorithm
-                        * to use the first bit found.
-                        */
-                       if (lowest_cpu != -1) {
-                               cpus_clear(*lowest_mask);
-                               cpu_set(rq->cpu, *lowest_mask);
-                       }
-                       return 1;
-               }
-
-               /* no locking for now */
-               if ((rq->rt.highest_prio > task->prio)
-                   && (rq->rt.highest_prio >= lowest_prio)) {
-                       if (rq->rt.highest_prio > lowest_prio) {
-                               /* new low - clear old data */
-                               lowest_prio = rq->rt.highest_prio;
-                               lowest_cpu = cpu;
-                               count = 0;
-                       }
-                       count++;
-               } else
-                       cpu_clear(cpu, *lowest_mask);
-       }
-
-       /*
-        * Clear out all the set bits that represent
-        * runqueues that were of higher prio than
-        * the lowest_prio.
-        */
-       if (lowest_cpu > 0) {
-               /*
-                * Perhaps we could add another cpumask op to
-                * zero out bits. Like cpu_zero_bits(cpumask, nrbits);
-                * Then that could be optimized to use memset and such.
-                */
-               for_each_cpu_mask(cpu, *lowest_mask) {
-                       if (cpu >= lowest_cpu)
-                               break;
-                       cpu_clear(cpu, *lowest_mask);
-               }
-       }
-
-       return count;
-}
-
 static inline int pick_optimal_cpu(int this_cpu, cpumask_t *mask)
 {
        int first;
@@ -851,17 +796,12 @@ static int find_lowest_rq(struct task_struct *task)
        cpumask_t *lowest_mask = &__get_cpu_var(local_cpu_mask);
        int this_cpu = smp_processor_id();
        int cpu      = task_cpu(task);
-       int count    = find_lowest_cpus(task, lowest_mask);
 
-       if (!count)
-               return -1; /* No targets found */
+       if (task->rt.nr_cpus_allowed == 1)
+               return -1; /* No other targets possible */
 
-       /*
-        * There is no sense in performing an optimal search if only one
-        * target is found.
-        */
-       if (count == 1)
-               return first_cpu(*lowest_mask);
+       if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
+               return -1; /* No targets found */
 
        /*
         * At this point we have built a mask of cpus representing the
@@ -1218,6 +1158,8 @@ static void join_domain_rt(struct rq *rq)
 {
        if (rq->rt.overloaded)
                rt_set_overload(rq);
+
+       cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio);
 }
 
 /* Assumes rq->lock is held */
@@ -1225,6 +1167,8 @@ static void leave_domain_rt(struct rq *rq)
 {
        if (rq->rt.overloaded)
                rt_clear_overload(rq);
+
+       cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
 }
 
 /*