Some operations on G1DirtyCardQueueSets are not really generic operations on any DCQS. Rather, they are really associated with the queue set in the barrier set. Similarly for SATBMarkQueueSets. An indicator that an operation probably isn't really be a generic qset operation is the use thread iteration in the implementation of the operation. Some of these operations ought to be moved to the barrier set. There might be static helpers on the qset classes though.