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 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
       -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 decon‐
              figured.

       -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  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
       chcpu has the following return codes:

       0      success

       1      failure

       64     partial success

AUTHOR
       Heiko Carstens ⟨heiko.carstens AT de.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/⟩.



util-linux                                  July 2014                                    CHCPU(8)