sched: fix newidle smp group balancing

Re-compute the shares on newidle - so we can make a decision based on
recent data.
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>

kernel/sched.c

@@ -1579,6 +1579,13 @@ static void update_shares(struct sched_domain *sd)
 	walk_tg_tree(tg_nop, tg_shares_up, 0, sd);
 }
 
+static void update_shares_locked(struct rq *rq, struct sched_domain *sd)
+{
+	spin_unlock(&rq->lock);
+	update_shares(sd);
+	spin_lock(&rq->lock);
+}
+
 static void update_h_load(int cpu)
 {
 	walk_tg_tree(tg_load_down, tg_nop, cpu, NULL);
@@ -1595,6 +1602,10 @@ static inline void update_shares(struct sched_domain *sd)
 {
 }
 
+static inline void update_shares_locked(struct rq *rq, struct sched_domain *sd)
+{
+}
+
 #endif
 
 #endif
@@ -3543,6 +3554,7 @@ load_balance_newidle(int this_cpu, struct rq *this_rq, struct sched_domain *sd,
 
 	schedstat_inc(sd, lb_count[CPU_NEWLY_IDLE]);
 redo:
+	update_shares_locked(this_rq, sd);
 	group = find_busiest_group(sd, this_cpu, &imbalance, CPU_NEWLY_IDLE,
 				   &sd_idle, cpus, NULL);
 	if (!group) {
@@ -3586,6 +3598,7 @@ redo:
 	} else
 		sd->nr_balance_failed = 0;
 
+	update_shares_locked(this_rq, sd);
 	return ld_moved;
 
 out_balanced: