sched: group scheduling, change how cpu load is calculated

This patch changes how the cpu load exerted by fair_sched_class tasks
is calculated. Load exerted by fair_sched_class tasks on a cpu is now
a summation of the group weights, rather than summation of task weights.
Weight exerted by a group on a cpu is dependent on the shares allocated
to it.

This version of patch has a minor impact on code size, but should have
no runtime/functional impact for !CONFIG_FAIR_GROUP_SCHED.

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/sched_rt.c

@@ -32,6 +32,7 @@ static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup)
 
 	list_add_tail(&p->run_list, array->queue + p->prio);
 	__set_bit(p->prio, array->bitmap);
+	inc_cpu_load(rq, p->se.load.weight);
 }
 
 /*
@@ -46,6 +47,7 @@ static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep)
 	list_del(&p->run_list);
 	if (list_empty(array->queue + p->prio))
 		__clear_bit(p->prio, array->bitmap);
+	dec_cpu_load(rq, p->se.load.weight);
 }
 
 /*