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 vir-
tual 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.
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/>.
Linux June 2012 CHCPU(8)
