CHCPU(8) System Administration CHCPU(8)
NAME
chcpu - configure CPUs
SYNOPSIS
chcpu -c|-d|-e|-g cpu-list
chcpu -p mode
chcpu -r|-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 ad-
dresses or ranges of addresses. For example, 0,5,7,9-11 makes the com-
mand applicable to the CPUs with the addresses 0, 5, 7, 9, 10, and 11.
OPTIONS
-c, --configure cpu-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, --disable cpu-list
Disable the specified CPUs. Disabling a CPU means that the ker-
nel sets it offline.
-e, --enable cpu-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, --deconfigure cpu-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.
-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.
-r, --rescan
Trigger a rescan of CPUs. After a rescan, the Linux kernel rec-
ognizes the new CPUs. Use this option on systems that do not
automatically detect newly attached CPUs.
-V, --version
Display version information and exit.
-h, --help
Display help text 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 <https://www.kernel.org/pub/linux/utils/util-
linux/>.
util-linux July 2014 CHCPU(8)