Deficit round robin (DRR) is a modified weighted round robin scheduling discipline. It can handle packets of variable size without knowing their mean size. WRR serves every nonempty queue whereas DRR serves packets at the head of every nonempty queue which deficit counter is greater than the packet's size. If it's lower then deficit counter is increased by some given value called quantum. Deficit counter is decreased by the size of packets being served.

See also: scheduling disciplines