CHCPU(8)		     System Administration		      CHCPU(8)

NAME
       chcpu - configure CPUs

SYNOPSIS
       chcpu -c|-d|-e|-g cpu-list

       chcpu -p mode

       chcpu -r|-h|-V

DESCRIPTION
       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.

OPTIONS
       -c, --configure cpu-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, --disable cpu-list
	   Disable the specified CPUs. Disabling a CPU means that the kernel
	   sets it offline.

       -e, --enable cpu-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, --deconfigure cpu-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, --dispatch mode
	   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.

EXIT STATUS
       chcpu has the following exit status values:

       0
	   success

       1
	   failure

       64
	   partial success

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

COPYRIGHT
       Copyright IBM Corp. 2011

SEE ALSO
       lscpu(1)

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

AVAILABILITY
       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 2.41.2		  2025-09-22			      CHCPU(8)