cpuplugd - Control CPUs and memory

LPAR mode z/VM guest KVM guest

Use the cpuplugd command and a set of rules in a configuration file to dynamically enable or disable CPUs. For Linux® on z/VM®, you can also dynamically add or remove memory.

Ubuntu Server 20.04.1 provides the cpuplugd utility as a package, s390-tools-cpuplugd.

When Linux is running in an LPAR, setting a CPU offline can result in the LPAR status "Exceptions" in the HMC or SE. With one or more CPUs offline, this status does not necessarily indicate a problem.

Rules that are tailored to a particular system environment and the associated workload can increase performance. The rules can include various system load variables.

Ubuntu Server 20.04.1 automatically starts cpuplugd for you after you install the package.

Note: Do not run multiple instances of cpuplugd simultaneously.

You can start cpuplugd from the command line in two ways:

With the service utility
Through a command-line interface