1. An apparatus, comprising: a pool of shared processing units; and a hypervisor, wherein the hypervisor assigns one or more processing units from the pool of shared processing units to a plurality of partitions in a shared processor logical partitioned environment; wherein a given partition within the plurality of partitions is configured to run an instance of an operating system; wherein the instance of the operating system identifies a processor percentage, wherein the processor percentage is a percentage of a physical processing unit used by the given partition, wherein the instance of the operating system is assigned a number of virtual processors, and wherein identifying the processor percentage comprises calculating a processor percentage per virtual processor to form a per-virtual-processor percentage; wherein the instance of the operating system adjusts a previously assigned time slice based on the processor percentage to form an adjusted time slice, wherein adjusting the previously assigned time slice comprises multiplying a value of the previously assigned time slice by the per-virtual-processor percentage, and wherein the instance of the operating system allots the adjusted time slice to a thread running in the instance of the operating system.