1. A method for dispatching a software thread to a logical processor in a shared processor logical partition, the method comprising: responsive to a software thread being made ready to run by an operating system, identifying a last logical processor on which the software thread was last dispatched; determining whether the last logical processor on which the software thread was dispatched is idle; responsive to a determination that the last logical processor on which the software thread was dispatched is not idle, selecting a logical processor that is idle and currently dispatched on a physical processor to the operating system and queuing the software thread to run on the selected logical processor; responsive to a determination that the last logical processor on which the software thread was dispatched is idle, determining whether the last logical processor on which the software thread was dispatched is currently dispatched on a physical processor to the operating system; responsive to a determination that the last logical processor on which the software thread was dispatched is not currently dispatched to the operating system, selecting a logical processor that is idle and currently dispatched on a physical processor to the operating system and queuing the software thread to run on the selected logical processor.