chcpu - configure CPUs

       Heiko Carstens <heiko.carstens@de.ibm.com>

       The chcpu command is part of the util-linux package which can be downloaded from Linux Kernel Archive
       <https://www.kernel.org/pub/linux/utils/util-linux/>.

util-linux 2.41                                    2025-02-26                                           CHCPU(8)

       Copyright IBM Corp. 2011

chcpu can modify the state of CPUs. It can enable or disable CPUs, scan for new CPUs, change the CPU
       dispatching mode of the underlying hypervisor, and request CPUs from the hypervisor (configure) or return
       CPUs to the hypervisor (deconfigure).

       Some options have a cpu-list argument. Use this argument to specify a comma-separated list of CPUs. The
       list can contain individual CPU addresses or ranges of addresses. For example, 0,5,7,9-11 makes the
       command applicable to the CPUs with the addresses 0, 5, 7, 9, 10, and 11.

chcpu has the following exit status values:

       0
           success

       1
           failure

       64
           partial success

       chcpu - configure CPUs

-c, --configurecpu-list
           Configure the specified CPUs. Configuring a CPU means that the hypervisor takes a CPU from the CPU
           pool and assigns it to the virtual hardware on which your kernel runs.

       -d, --disablecpu-list
           Disable the specified CPUs. Disabling a CPU means that the kernel sets it offline.

       -e, --enablecpu-list
           Enable the specified CPUs. Enabling a CPU means that the kernel sets it online. A CPU must be
           configured, see -c, before it can be enabled.

       -g, --deconfigurecpu-list
           Deconfigure the specified CPUs. Deconfiguring a CPU means that the hypervisor removes the CPU from
           the virtual hardware on which the Linux instance runs and returns it to the CPU pool. A CPU must be
           offline, see -d, before it can be deconfigured.

           chcpu-g is not supported on IBM z/VM, CPUs are always in a configured state.

           if chcpu-g is supported, any disabled CPUs should be deconfigured to inform the hypervisor that
           these CPUs won’t be used, avoiding potential performance penalties.

       -p, --dispatchmode
           Set the CPU dispatching mode (polarization). This option has an effect only if your hardware
           architecture and hypervisor support CPU polarization. Available modes are:

           horizontal
               The workload is spread across all available CPUs.

           vertical
               The workload is concentrated on few CPUs.

       -r, --rescan
           Trigger a rescan of CPUs. After a rescan, the Linux kernel recognizes the new CPUs. Use this option
           on systems that do not automatically detect newly attached CPUs.

       -h, --help
           Display help text and exit.

       -V, --version
           Display version and exit.

       For bug reports, use the issue tracker <https://github.com/util-linux/util-linux/issues>.

lscpu(1)

chcpu-c|-d|-e|-gcpu-listchcpu-pmodechcpu-r|-h|-V