CPUCTL(8) BSD System Manager's Manual CPUCTL(8)NAME
cpuctl -- program to control CPUs
cpuctl command [arguments]
The cpuctl command can be used to control and inspect the state of CPUs in the system.
The first argument, command, specifies the action to take. Valid commands are:
identify cpu Output information on the specified CPU's features and capabilities. Not available on all architectures.
list For each CPU in the system, display the current state and time of the last state change.
offline cpuno Set the specified CPU off line.
Unbound LWPs (lightweight processes) will not be executed on the CPU while it is off line. Bound LWPs will continue to be
executed on the CPU, and device interrupts routed to the CPU will continue to be handled. A future release of the system
may allow device interrupts to be re-routed away from individual CPUs.
At least one CPU in the system must remain on line.
online cpuno Set the specified CPU on line, making it available to run unbound LWPs.
ucode [file] This applies the microcode patch on all CPUs. The default filename is used if no filename is specified. The identify com-
mand prints the installed version on that CPU. On success the identify command show different ucode versions before and
after this command.
/dev/cpuctl control device
The directory to install the microcode file for AMD CPUs into. The default filename is microcode_amd.bin for CPU families 0x10
to 0x14. The default filename is microcode_amd_famXXh.bin where XX is the CPU family starting with 15 (hex). Get it from
cpuctl identify 0
and you should see something like this:
cpu0: UCode version: 0x1000080
After applying the microcode patch with
you can see with
cpuctl identify 0
that the patch got applied:
cpu0: UCode version: 0x1000083
SEE ALSO psrset(8), schedctl(8)HISTORY
The cpuctl command first appeared in NetBSD 5.0.
BSD January 13, 2012 BSD
Check Out this Related Man Page
CHCPU(8) System Administration CHCPU(8)NAME
chcpu - configure CPUs
chcpu -c|-d|-e|-g cpu-list
chcpu -p mode
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
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 vir-
tual hardware on which your kernel runs.
-d, --disable cpu-list
Disable the specified CPUs. Disabling a CPU means that the kernel 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
-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.
Trigger a rescan of CPUs. After a rescan, the Linux kernel recognizes the new CPUs. Use this option on systems that do not auto-
matically detect newly attached CPUs.
Display version information and exit.
Display help text and exit.
chcpu has the following return codes:
64 partial success
Heiko Carstens <email@example.com>
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 July 2014 CHCPU(8)