Open Source Software

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 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
          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@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/.



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