Shared central processors

LPs can share CPs with other LPs. A sharing LP does not have exclusive use of the physical cores. There is no correspondence between the logical cores in a sharing LP and the physical cores on which the logical cores are dispatched (except on a one-way CPC). A logical core can be dispatched on any physical core and, on successive dispatches, the logical core can be dispatched on different physical cores.

The number of CPs available for use by sharing LPs is determined by adding the number of CPs already assigned to active, dedicated LPs and subtracting that sum from the total number of physical cores available.

The total of all logical cores for all sharing LPs can be larger than the number of physical cores serving the sharing LPs. For example, if four LPs are active on a six-way CPC and each LP is defined to have four CPs, the total number of online logical cores is 16.

For coupling facility considerations, see Processor considerations for coupling facility LPs.

Use the Customize/Delete Activation Profiles task to open a reset or image profile to define shared CPs for an LP. The Dedicated processors check box is located in the Logical processor assignment group box on the Processor page for the LP.