A computer implemented method, data processing system, and computer usable program code are provided for dispatching virtual processors. A determination is made as to whether a physical processor in a set of physical processors is idle, and, if so, a determination is made as to whether an affinity map for the idle physical processor exists. Responsive to an existence of the affinity map, a determination is made as to whether a virtual processor last mapped to the idle physical processor is ready to run using the affinity map and a dispatch algorithm. Responsive to identifying a ready-to-run virtual processor whose affinity map indicates that the idle physical processor is mapped to this virtual processor in its preceding dispatch, the ready-to-run virtual processor is dispatched to the idle physical processor. Thus, memory affinity is maintained between physical and virtual processors when the memory affinity is not expired.