chcpu

(8)

configure CPUs

Administration and privileged commands 8 optionsutil-linux 2.41-5

chcpu -c|-d|-e|-g cpu-list chcpu -p mode chcpu -r|-h|-V

Options

-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.

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.

EXIT STATUS

chcpu has the following exit status values:

success

failure

partial success

AUTHORS

Heiko Carstens heiko.carstens@de.ibm.com

COPYRIGHT

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/.