maxcpus - Limit the number of CPUs Linux can use at IPL

Use the maxcpus= kernel parameter to limit the number of CPUs that Linux® can use at IPL and that are online after IPL.

If the real or virtual hardware provides more than the specified number of CPUs, these surplus CPUs are initially offline. For example, if five CPUs are available, maxcpus=2 results in two online CPUs and three offline CPUs after IPL.

Offline CPUs can be set online dynamically unless the possible_cpus= parameter is set and specifies a maximum number of online CPUs that is already reached. The possible_cpus= parameter sets an absolute limit for the number of CPUs that can be online at any one time (see possible_cpus). If both maxcpus= and possible_cpus= are set, a lower value for possible_cpus= overrides maxcpus= and makes it ineffective.