# PROCESSOR_AFFINITY

New in version 3.12.

Set to a true value to ask CTest to launch the test process with CPU affinity for a fixed set of processors. If enabled and supported for the current platform, CTest will choose a set of processors to place in the CPU affinity mask when launching the test process. The number of processors in the set is determined by the `PROCESSORS` test property or the number of processors available to CTest, whichever is smaller. The set of processors chosen will be disjoint from the processors assigned to other concurrently running tests that also have the `PROCESSOR_AFFINITY` property enabled.