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
	      virtual 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 ker-
	      nel 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.


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/>.



Linux				   June 2012			      CHCPU(8)