sched: clean up wakeup balancing, rename variables
[sfrench/cifs-2.6.git] / kernel / sched_fair.c
index 3df4d46994ca80ddc861ba44fe8f7ac24b3c50ed..2d2be02b8e3b106ee6f3379ae182a6073cd0b538 100644 (file)
@@ -175,8 +175,15 @@ static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
         * Maintain a cache of leftmost tree entries (it is frequently
         * used):
         */
-       if (leftmost)
+       if (leftmost) {
                cfs_rq->rb_leftmost = &se->run_node;
+               /*
+                * maintain cfs_rq->min_vruntime to be a monotonic increasing
+                * value tracking the leftmost vruntime in the tree.
+                */
+               cfs_rq->min_vruntime =
+                       max_vruntime(cfs_rq->min_vruntime, se->vruntime);
+       }
 
        rb_link_node(&se->run_node, parent, link);
        rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
@@ -184,8 +191,24 @@ static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
 
 static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
-       if (cfs_rq->rb_leftmost == &se->run_node)
-               cfs_rq->rb_leftmost = rb_next(&se->run_node);
+       if (cfs_rq->rb_leftmost == &se->run_node) {
+               struct rb_node *next_node;
+               struct sched_entity *next;
+
+               next_node = rb_next(&se->run_node);
+               cfs_rq->rb_leftmost = next_node;
+
+               if (next_node) {
+                       next = rb_entry(next_node,
+                                       struct sched_entity, run_node);
+                       cfs_rq->min_vruntime =
+                               max_vruntime(cfs_rq->min_vruntime,
+                                            next->vruntime);
+               }
+       }
+
+       if (cfs_rq->next == se)
+               cfs_rq->next = NULL;
 
        rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
 }
@@ -260,12 +283,8 @@ static u64 __sched_period(unsigned long nr_running)
  */
 static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
-       u64 slice = __sched_period(cfs_rq->nr_running);
-
-       slice *= se->load.weight;
-       do_div(slice, cfs_rq->load.weight);
-
-       return slice;
+       return calc_delta_mine(__sched_period(cfs_rq->nr_running),
+                              se->load.weight, &cfs_rq->load);
 }
 
 /*
@@ -303,7 +322,6 @@ __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
              unsigned long delta_exec)
 {
        unsigned long delta_exec_weighted;
-       u64 vruntime;
 
        schedstat_set(curr->exec_max, max((u64)delta_exec, curr->exec_max));
 
@@ -315,19 +333,6 @@ __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
                                                        &curr->load);
        }
        curr->vruntime += delta_exec_weighted;
-
-       /*
-        * maintain cfs_rq->min_vruntime to be a monotonic increasing
-        * value tracking the leftmost vruntime in the tree.
-        */
-       if (first_fair(cfs_rq)) {
-               vruntime = min_vruntime(curr->vruntime,
-                               __pick_next_entity(cfs_rq)->vruntime);
-       } else
-               vruntime = curr->vruntime;
-
-       cfs_rq->min_vruntime =
-               max_vruntime(cfs_rq->min_vruntime, vruntime);
 }
 
 static void update_curr(struct cfs_rq *cfs_rq)
@@ -493,7 +498,11 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
 {
        u64 vruntime;
 
-       vruntime = cfs_rq->min_vruntime;
+       if (first_fair(cfs_rq)) {
+               vruntime = min_vruntime(cfs_rq->min_vruntime,
+                               __pick_next_entity(cfs_rq)->vruntime);
+       } else
+               vruntime = cfs_rq->min_vruntime;
 
        if (sched_feat(TREE_AVG)) {
                struct sched_entity *last = __pick_last_entity(cfs_rq);
@@ -515,8 +524,10 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
 
        if (!initial) {
                /* sleeps upto a single latency don't count. */
-               if (sched_feat(NEW_FAIR_SLEEPERS))
-                       vruntime -= sysctl_sched_latency;
+               if (sched_feat(NEW_FAIR_SLEEPERS)) {
+                       vruntime -= calc_delta_fair(sysctl_sched_latency,
+                                                   &cfs_rq->load);
+               }
 
                /* ensure we never gain time by being placed backwards. */
                vruntime = max_vruntime(se->vruntime, vruntime);
@@ -616,12 +627,32 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
        se->prev_sum_exec_runtime = se->sum_exec_runtime;
 }
 
+static struct sched_entity *
+pick_next(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+       s64 diff, gran;
+
+       if (!cfs_rq->next)
+               return se;
+
+       diff = cfs_rq->next->vruntime - se->vruntime;
+       if (diff < 0)
+               return se;
+
+       gran = calc_delta_fair(sysctl_sched_wakeup_granularity, &cfs_rq->load);
+       if (diff > gran)
+               return se;
+
+       return cfs_rq->next;
+}
+
 static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
 {
        struct sched_entity *se = NULL;
 
        if (first_fair(cfs_rq)) {
                se = __pick_next_entity(cfs_rq);
+               se = pick_next(cfs_rq, se);
                set_next_entity(cfs_rq, se);
        }
 
@@ -949,23 +980,74 @@ static inline int wake_idle(int cpu, struct task_struct *p)
 #endif
 
 #ifdef CONFIG_SMP
+
+static int
+wake_affine(struct rq *rq, struct sched_domain *this_sd, struct task_struct *p,
+           int prev_cpu, int this_cpu, int sync, int idx,
+           unsigned long load, unsigned long this_load,
+           unsigned int imbalance)
+{
+       unsigned long tl = this_load;
+       unsigned long tl_per_task;
+
+       if (!(this_sd->flags & SD_WAKE_AFFINE))
+               return 0;
+
+       /*
+        * Attract cache-cold tasks on sync wakeups:
+        */
+       if (sync && !task_hot(p, rq->clock, this_sd))
+               return 1;
+
+       schedstat_inc(p, se.nr_wakeups_affine_attempts);
+       tl_per_task = cpu_avg_load_per_task(this_cpu);
+
+       /*
+        * If sync wakeup then subtract the (maximum possible)
+        * effect of the currently running task from the load
+        * of the current CPU:
+        */
+       if (sync)
+               tl -= current->se.load.weight;
+
+       if ((tl <= load && tl + target_load(prev_cpu, idx) <= tl_per_task) ||
+                       100*(tl + p->se.load.weight) <= imbalance*load) {
+               /*
+                * This domain has SD_WAKE_AFFINE and
+                * p is cache cold in this domain, and
+                * there is no bad imbalance.
+                */
+               schedstat_inc(this_sd, ttwu_move_affine);
+               schedstat_inc(p, se.nr_wakeups_affine);
+
+               return 1;
+       }
+       return 0;
+}
+
 static int select_task_rq_fair(struct task_struct *p, int sync)
 {
-       int cpu, this_cpu;
-       struct rq *rq;
        struct sched_domain *sd, *this_sd = NULL;
-       int new_cpu;
+       int prev_cpu, this_cpu, new_cpu;
+       unsigned long load, this_load;
+       unsigned int imbalance;
+       struct rq *rq;
+       int idx;
 
-       cpu      = task_cpu(p);
-       rq       = task_rq(p);
-       this_cpu = smp_processor_id();
-       new_cpu  cpu;
+       prev_cpu        = task_cpu(p);
+       rq              = task_rq(p);
+       this_cpu        = smp_processor_id();
+       new_cpu         = prev_cpu;
 
-       if (cpu == this_cpu)
+       if (prev_cpu == this_cpu)
                goto out_set_cpu;
 
+       /*
+        * 'this_sd' is the first domain that both
+        * this_cpu and prev_cpu are present in:
+        */
        for_each_domain(this_cpu, sd) {
-               if (cpu_isset(cpu, sd->span)) {
+               if (cpu_isset(prev_cpu, sd->span)) {
                        this_sd = sd;
                        break;
                }
@@ -977,67 +1059,40 @@ static int select_task_rq_fair(struct task_struct *p, int sync)
        /*
         * Check for affine wakeup and passive balancing possibilities.
         */
-       if (this_sd) {
-               int idx = this_sd->wake_idx;
-               unsigned int imbalance;
-               unsigned long load, this_load;
-
-               imbalance = 100 + (this_sd->imbalance_pct - 100) / 2;
-
-               load = source_load(cpu, idx);
-               this_load = target_load(this_cpu, idx);
-
-               new_cpu = this_cpu; /* Wake to this CPU if we can */
-
-               if (this_sd->flags & SD_WAKE_AFFINE) {
-                       unsigned long tl = this_load;
-                       unsigned long tl_per_task;
-
-                       /*
-                        * Attract cache-cold tasks on sync wakeups:
-                        */
-                       if (sync && !task_hot(p, rq->clock, this_sd))
-                               goto out_set_cpu;
-
-                       schedstat_inc(p, se.nr_wakeups_affine_attempts);
-                       tl_per_task = cpu_avg_load_per_task(this_cpu);
-
-                       /*
-                        * If sync wakeup then subtract the (maximum possible)
-                        * effect of the currently running task from the load
-                        * of the current CPU:
-                        */
-                       if (sync)
-                               tl -= current->se.load.weight;
-
-                       if ((tl <= load &&
-                               tl + target_load(cpu, idx) <= tl_per_task) ||
-                              100*(tl + p->se.load.weight) <= imbalance*load) {
-                               /*
-                                * This domain has SD_WAKE_AFFINE and
-                                * p is cache cold in this domain, and
-                                * there is no bad imbalance.
-                                */
-                               schedstat_inc(this_sd, ttwu_move_affine);
-                               schedstat_inc(p, se.nr_wakeups_affine);
-                               goto out_set_cpu;
-                       }
-               }
+       if (!this_sd)
+               goto out_keep_cpu;
 
-               /*
-                * Start passive balancing when half the imbalance_pct
-                * limit is reached.
-                */
-               if (this_sd->flags & SD_WAKE_BALANCE) {
-                       if (imbalance*this_load <= 100*load) {
-                               schedstat_inc(this_sd, ttwu_move_balance);
-                               schedstat_inc(p, se.nr_wakeups_passive);
-                               goto out_set_cpu;
-                       }
+       idx = this_sd->wake_idx;
+
+       imbalance = 100 + (this_sd->imbalance_pct - 100) / 2;
+
+       load = source_load(prev_cpu, idx);
+       this_load = target_load(this_cpu, idx);
+
+       new_cpu = this_cpu; /* Wake to this CPU if we can */
+
+       if (wake_affine(rq, this_sd, p, prev_cpu, this_cpu, sync, idx,
+                                    load, this_load, imbalance))
+               goto out_set_cpu;
+
+       /*
+        * Start passive balancing when half the imbalance_pct
+        * limit is reached.
+        */
+       if (this_sd->flags & SD_WAKE_BALANCE) {
+               if (imbalance*this_load <= 100*load) {
+                       schedstat_inc(this_sd, ttwu_move_balance);
+                       schedstat_inc(p, se.nr_wakeups_passive);
+                       goto out_set_cpu;
                }
        }
 
-       new_cpu = cpu; /* Could not wake to this_cpu. Wake to cpu instead */
+out_keep_cpu:
+       /*
+        * Could not wake to this_cpu.
+        * Wake to the previous cpu instead:
+        */
+       new_cpu = prev_cpu;
 out_set_cpu:
        return wake_idle(new_cpu, p);
 }
@@ -1060,6 +1115,9 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
                resched_task(curr);
                return;
        }
+
+       cfs_rq_of(pse)->next = pse;
+
        /*
         * Batch tasks do not preempt (their preemption is driven by
         * the tick):
@@ -1353,6 +1411,16 @@ static void set_curr_task_fair(struct rq *rq)
                set_next_entity(cfs_rq_of(se), se);
 }
 
+#ifdef CONFIG_FAIR_GROUP_SCHED
+static void moved_group_fair(struct task_struct *p)
+{
+       struct cfs_rq *cfs_rq = task_cfs_rq(p);
+
+       update_curr(cfs_rq);
+       place_entity(cfs_rq, &p->se, 1);
+}
+#endif
+
 /*
  * All the scheduling class methods:
  */
@@ -1381,6 +1449,10 @@ static const struct sched_class fair_sched_class = {
 
        .prio_changed           = prio_changed_fair,
        .switched_to            = switched_to_fair,
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+       .moved_group            = moved_group_fair,
+#endif
 };
 
 #ifdef CONFIG_SCHED_DEBUG