[PATCH] sched: minor cleanups

From: Nick Piggin <nickpiggin@yahoo.com.au>

Minor cleanups from Ingo's patch including task_hot (do it right in
try_to_wake_up too).

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 532d82be217df34d0ea334c92f3ceff1432f6179..e47ff84b476159c1b073be7deebb597f7b5be49d 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -597,9 +597,9 @@ struct sched_domain {
        .cache_nice_tries       = 0,                    \
        .per_cpu_gain           = 15,                   \
        .flags                  = SD_BALANCE_NEWIDLE    \
-                                | SD_WAKE_AFFINE       \
-                                | SD_WAKE_IDLE         \
-                                | SD_SHARE_CPUPOWER,   \
+                               | SD_WAKE_AFFINE        \
+                               | SD_WAKE_IDLE          \
+                               | SD_SHARE_CPUPOWER,    \
        .last_balance           = jiffies,              \
        .balance_interval       = 1,                    \
        .nr_balance_failed      = 0,                    \

diff --git a/kernel/sched.c b/kernel/sched.c
index 79b86fe0374db9b3d0b5c856703dd6d6787bdcad..71fb135006206224825b12505521d8762dd5a313 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -187,6 +187,8 @@ static inline unsigned int task_timeslice(task_t *p)
        return BASE_TIMESLICE(p);
 }
 
+#define task_hot(p, now, sd) ((now) - (p)->timestamp < (sd)->cache_hot_time)
+
 /*
  * These are the runqueue data structures:
  */
@@ -704,13 +706,11 @@ static inline int wake_idle(int cpu, task_t *p)
  */
 static int try_to_wake_up(task_t * p, unsigned int state, int sync)
 {
+       int cpu, this_cpu, success = 0;
        unsigned long flags;
-       int success = 0;
        long old_state;
        runqueue_t *rq;
-       int cpu, this_cpu;
 #ifdef CONFIG_SMP
-       unsigned long long now;
        unsigned long load, this_load;
        struct sched_domain *sd;
        int new_cpu;
@@ -753,8 +753,6 @@ static int try_to_wake_up(task_t * p, unsigned int state, int sync)
        if (load > this_load + SCHED_LOAD_SCALE*2)
                goto out_set_cpu;
 
-       now = sched_clock();
-
        /*
         * Migrate the task to the waking domain.
         * Do not violate hard affinity.
@@ -762,7 +760,7 @@ static int try_to_wake_up(task_t * p, unsigned int state, int sync)
        for_each_domain(this_cpu, sd) {
                if (!(sd->flags & SD_WAKE_AFFINE))
                        break;
-               if (rq->timestamp_last_tick - p->timestamp < sd->cache_hot_time)
+               if (task_hot(p, rq->timestamp_last_tick, sd))
                        break;
 
                if (cpu_isset(cpu, sd->span))
@@ -774,22 +772,18 @@ out_set_cpu:
        new_cpu = wake_idle(new_cpu, p);
        if (new_cpu != cpu && cpu_isset(new_cpu, p->cpus_allowed)) {
                set_task_cpu(p, new_cpu);
-               goto repeat_lock_task;
-       }
-       goto out_activate;
-
-repeat_lock_task:
-       task_rq_unlock(rq, &flags);
-       rq = task_rq_lock(p, &flags);
-       old_state = p->state;
-       if (!(old_state & state))
-               goto out;
-
-       if (p->array)
-               goto out_running;
+               task_rq_unlock(rq, &flags);
+               /* might preempt at this point */
+               rq = task_rq_lock(p, &flags);
+               old_state = p->state;
+               if (!(old_state & state))
+                       goto out;
+               if (p->array)
+                       goto out_running;
 
-       this_cpu = smp_processor_id();
-       cpu = task_cpu(p);
+               this_cpu = smp_processor_id();
+               cpu = task_cpu(p);
+       }
 
 out_activate:
 #endif /* CONFIG_SMP */
@@ -1301,7 +1295,7 @@ int can_migrate_task(task_t *p, runqueue_t *rq, int this_cpu,
        /* Aggressive migration if we've failed balancing */
        if (idle == NEWLY_IDLE ||
                        sd->nr_balance_failed < sd->cache_nice_tries) {
-               if (rq->timestamp_last_tick - p->timestamp < sd->cache_hot_time)
+               if (task_hot(p, rq->timestamp_last_tick, sd))
                        return 0;
        }
 
@@ -1319,10 +1313,9 @@ static int move_tasks(runqueue_t *this_rq, int this_cpu, runqueue_t *busiest,
                        unsigned long max_nr_move, struct sched_domain *sd,
                        enum idle_type idle)
 {
-       int idx;
-       int pulled = 0;
        prio_array_t *array, *dst_array;
        struct list_head *head, *curr;
+       int idx, pulled = 0;
        task_t *tmp;
 
        if (max_nr_move <= 0 || busiest->nr_running <= 1)
@@ -1411,10 +1404,8 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
                /* Tally up the load of all CPUs in the group */
                avg_load = 0;
                cpus_and(tmp, group->cpumask, cpu_online_map);
-               if (unlikely(cpus_empty(tmp))) {
-                       WARN_ON(1);
-                       return NULL;
-               }
+               if (unlikely(cpus_empty(tmp)))
+                       goto nextgroup;
 
                for_each_cpu_mask(i, tmp) {
                        /* Bias balancing toward cpus of our domain */