sched: revert revert of: fair-group: SMP-nice for group scheduling

Try again..

Initial commit: 18d95a2832c1392a2d63227a7a6d433cb9f2037e
Revert: 6363ca57c76b7b83639ca8c83fc285fa26a7880e

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 80 insertions, 44 deletions

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 2e197b8e43f1..183388c4dead 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -567,10 +567,27 @@ update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
  * Scheduling class queueing methods:
  */
 
+#if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
+static void
+add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
+{
+        cfs_rq->task_weight += weight;
+}
+#else
+static inline void
+add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
+{
+}
+#endif
+
 static void
 account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
         update_load_add(&cfs_rq->load, se->load.weight);
+        if (!parent_entity(se))
+                inc_cpu_load(rq_of(cfs_rq), se->load.weight);
+        if (entity_is_task(se))
+                add_cfs_task_weight(cfs_rq, se->load.weight);
         cfs_rq->nr_running++;
         se->on_rq = 1;
         list_add(&se->group_node, &cfs_rq->tasks);
@@ -580,6 +597,10 @@ static void
 account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
         update_load_sub(&cfs_rq->load, se->load.weight);
+        if (!parent_entity(se))
+                dec_cpu_load(rq_of(cfs_rq), se->load.weight);
+        if (entity_is_task(se))
+                add_cfs_task_weight(cfs_rq, -se->load.weight);
         cfs_rq->nr_running--;
         se->on_rq = 0;
         list_del_init(&se->group_node);
@@ -1372,75 +1393,90 @@ static struct task_struct *load_balance_next_fair(void *arg)
         return __load_balance_iterator(cfs_rq, cfs_rq->balance_iterator);
 }
 
-#ifdef CONFIG_FAIR_GROUP_SCHED
-static int cfs_rq_best_prio(struct cfs_rq *cfs_rq)
+static unsigned long
+__load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
+                unsigned long max_load_move, struct sched_domain *sd,
+                enum cpu_idle_type idle, int *all_pinned, int *this_best_prio,
+                struct cfs_rq *cfs_rq)
 {
-        struct sched_entity *curr;
-        struct task_struct *p;
-
-        if (!cfs_rq->nr_running || !first_fair(cfs_rq))
-                return MAX_PRIO;
-
-        curr = cfs_rq->curr;
-        if (!curr)
-                curr = __pick_next_entity(cfs_rq);
+        struct rq_iterator cfs_rq_iterator;
 
-        p = task_of(curr);
+        cfs_rq_iterator.start = load_balance_start_fair;
+        cfs_rq_iterator.next = load_balance_next_fair;
+        cfs_rq_iterator.arg = cfs_rq;
 
-        return p->prio;
+        return balance_tasks(this_rq, this_cpu, busiest,
+                        max_load_move, sd, idle, all_pinned,
+                        this_best_prio, &cfs_rq_iterator);
 }
-#endif
 
+#ifdef CONFIG_FAIR_GROUP_SCHED
 static unsigned long
 load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
                   unsigned long max_load_move,
                   struct sched_domain *sd, enum cpu_idle_type idle,
                   int *all_pinned, int *this_best_prio)
 {
-        struct cfs_rq *busy_cfs_rq;
         long rem_load_move = max_load_move;
-        struct rq_iterator cfs_rq_iterator;
-
-        cfs_rq_iterator.start = load_balance_start_fair;
-        cfs_rq_iterator.next = load_balance_next_fair;
+        int busiest_cpu = cpu_of(busiest);
+        struct task_group *tg;
 
-        for_each_leaf_cfs_rq(busiest, busy_cfs_rq) {
-#ifdef CONFIG_FAIR_GROUP_SCHED
-                struct cfs_rq *this_cfs_rq;
+        rcu_read_lock();
+        list_for_each_entry(tg, &task_groups, list) {
                 long imbalance;
-                unsigned long maxload;
+                unsigned long this_weight, busiest_weight;
+                long rem_load, max_load, moved_load;
+
+                /*
+                 * empty group
+                 */
+                if (!aggregate(tg, sd)->task_weight)
+                        continue;
+
+                rem_load = rem_load_move * aggregate(tg, sd)->rq_weight;
+                rem_load /= aggregate(tg, sd)->load + 1;
+
+                this_weight = tg->cfs_rq[this_cpu]->task_weight;
+                busiest_weight = tg->cfs_rq[busiest_cpu]->task_weight;
 
-                this_cfs_rq = cpu_cfs_rq(busy_cfs_rq, this_cpu);
+                imbalance = (busiest_weight - this_weight) / 2;
 
-                imbalance = busy_cfs_rq->load.weight - this_cfs_rq->load.weight;
-                /* Don't pull if this_cfs_rq has more load than busy_cfs_rq */
-                if (imbalance <= 0)
+                if (imbalance < 0)
+                        imbalance = busiest_weight;
+
+                max_load = max(rem_load, imbalance);
+                moved_load = __load_balance_fair(this_rq, this_cpu, busiest,
+                                max_load, sd, idle, all_pinned, this_best_prio,
+                                tg->cfs_rq[busiest_cpu]);
+
+                if (!moved_load)
                         continue;
 
-                /* Don't pull more than imbalance/2 */
-                imbalance /= 2;
-                maxload = min(rem_load_move, imbalance);
+                move_group_shares(tg, sd, busiest_cpu, this_cpu);
 
-                *this_best_prio = cfs_rq_best_prio(this_cfs_rq);
-#else
-# define maxload rem_load_move
-#endif
-                /*
-                 * pass busy_cfs_rq argument into
-                 * load_balance_[start|next]_fair iterators
-                 */
-                cfs_rq_iterator.arg = busy_cfs_rq;
-                rem_load_move -= balance_tasks(this_rq, this_cpu, busiest,
-                                               maxload, sd, idle, all_pinned,
-                                               this_best_prio,
-                                               &cfs_rq_iterator);
+                moved_load *= aggregate(tg, sd)->load;
+                moved_load /= aggregate(tg, sd)->rq_weight + 1;
 
-                if (rem_load_move <= 0)
+                rem_load_move -= moved_load;
+                if (rem_load_move < 0)
                         break;
         }
+        rcu_read_unlock();
 
         return max_load_move - rem_load_move;
 }
+#else
+static unsigned long
+load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
+                  unsigned long max_load_move,
+                  struct sched_domain *sd, enum cpu_idle_type idle,
+                  int *all_pinned, int *this_best_prio)
+{
+        return __load_balance_fair(this_rq, this_cpu, busiest,
+                        max_load_move, sd, idle, all_pinned,
+                        this_best_prio, &busiest->cfs);
+}
+#endif
 
 static int
 move_one_task_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,