NAME

chcpu - configure CPUs

SYNOPSIS

chcpu [-e] [-d] [-c] [-g] cpu-list
chcpu [-p] mode
chcpu -r
chcpu [-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

-r, --rescan: Trigger a rescan of CPUs. Use this option on systems that do not automatically detect newly attached CPUs. The Linux kernel then recognizes the new CPUs.
-c, --configure cpu-list: Configure all 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.
-e, --enable cpu-list: Enable all specified CPUs. Enabling a CPU means that the kernel sets it online. A CPU must be configured, see -c, before it can be enabled.
-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.

-d, --disable cpu-list: Disable all specified CPUs. Disabling a CPU means that the kernel sets it offline.
-g, --deconfigure cpu-list: Deconfigure all 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.
-h, --help: Display help information and exit.
-V, --version: Display version information and exit.

RETURN CODES

chcpu has the following return codes:

0: success
1: failure
64: partial success

AUTHOR

Heiko Carstens

COPYRIGHT

AVAILABILITY

The chcpu command is part of the util-linux package and is available from Linux Kernel Archive.