@Override
  protected double getCostFromRl(BalancerRegionLoad rl) {
    return rl.getCpRequestsCount();
  }
Compute the cost of total number of coprocessor requests The more unbalanced the higher the
computed cost will be. This uses a rolling average of regionload.
hbase-balancer/src/main/java/org/apache/hadoop/hbase/master/balancer/CPRequestCostFunction.java