1. An apparatus comprising: a logically partitioned computer including a plurality of logical partitions, a first of which including a plurality of virtual processors used to schedule threads and that share at least one CPU; and a program resident in a hypervisor of the computer, wherein the program is configured to assign and dispatch the CPU to the plurality of virtual processors, the program configured to initiate a request for a yield of the CPU controlled by a yielding virtual processor, wherein the request designates a target virtual processor from among the plurality of virtual processors; and further configured to logically reassign control of the CPU from the yielding virtual processor to the target virtual processor.