chcpu(8) - phpMan

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 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 decon-
figured.

-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 AT de.com>