CHCPU(8) User Manuals CHCPU(8)

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 ker- nel 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.

AUTHOR Heiko Carstens

COPYRIGHT Copyright IBM Corp. 2011

SEE ALSO lscpu(1)

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

Linux June 2012 CHCPU(8)