CHCPU(8)                    System Administration                   CHCPU(8)

NAME         top

       chcpu - configure CPUs

SYNOPSIS         top

       chcpu -c|-d|-e|-g cpu-list
       chcpu -p mode
       chcpu -r|-h|-V

DESCRIPTION         top

       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         top

       -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
              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 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

       -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
                     vertical    The workload is concentrated on few CPUs.

       -r, --rescan
              Trigger a rescan of CPUs.  After a rescan, the Linux kernel
              recognizes 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         top

       chcpu has the following return codes:

       0      success

       1      failure

       64     partial success

AUTHOR         top

       Heiko Carstens ⟨⟩

COPYRIGHT         top

       Copyright IBM Corp. 2011

SEE ALSO         top


AVAILABILITY         top

       The chcpu command is part of the util-linux package and is available
       from Linux Kernel Archive 

COLOPHON         top

       This page is part of the util-linux (a random collection of Linux
       utilities) project.  Information about the project can be found at 
       ⟨⟩.  If you have a
       bug report for this manual page, send it to  This page was obtained from the
       project's upstream Git repository 
       ⟨git://⟩ on
       2017-03-13.  If you discover any rendering problems in this HTML ver‐
       sion of the page, or you believe there is a better or more up-to-date
       source for the page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of the original man‐
       ual page), send a mail to

util-linux                        July 2014                         CHCPU(8)