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 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 (heiko.carstens@de.ibm.com)

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 (ftp://ftp.kernel.org/pub/linux/utils/util-linux/).