A method for calculating flow control credits includes determining a number of entries added to each of a pair of storage devices, determining a number of entries removed from each of the storage devices, calculating a difference between available space in the storage devices, and calculating a number of credits to release based on the numbers of entries added to each of the storage devices, on the numbers of entries removed from each of the storage devices, and on the difference in available space. Entries removed from one storage device are treated as an entry added to the other storage device.