1CHCPU(8)                         User Manuals                         CHCPU(8)
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NAME

6       chcpu - configure CPUs
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SYNOPSIS

9       chcpu [-e] [-d] [-c] [-g] cpu-list
10       chcpu [-p] mode
11       chcpu -r
12       chcpu [-h] [-V]
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DESCRIPTION

15       chcpu  can  modify  the  state of CPUs.  It can enable or disable CPUs,
16       scan for new CPUs, change the CPU dispatching mode  of  the  underlying
17       hypervisor,  and request CPUs from the hypervisor (configure) or return
18       CPUs to the hypervisor (deconfigure).
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20       Some options have a cpu-list argument.  Use this argument to specify  a
21       comma-separated  list  of  CPUs.   The  list can contain individual CPU
22       addresses or ranges of addresses.  For example,  0,5,7,9-11  makes  the
23       command  applicable  to the CPUs with the addresses 0, 5, 7, 9, 10, and
24       11.
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OPTIONS

27       -r, --rescan
28              Trigger a rescan of CPUs.  Use this option on  systems  that  do
29              not  automatically detect newly attached CPUs.  The Linux kernel
30              then recognizes the new CPUs.
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32       -c, --configure cpu-list
33              Configure all specified CPUs.  Configuring a CPU means that  the
34              hypervisor  takes  a CPU from the CPU pool and assigns it to the
35              virtual hardware on which your kernel runs.
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37       -e, --enable cpu-list
38              Enable all specified CPUs.  Enabling a CPU means that the kernel
39              sets it online.  A CPU must be configured, see -c, before it can
40              be enabled.
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42       -p, --dispatch mode
43              Set the CPU dispatching mode (polarization).  This option has an
44              effect only if your hardware architecture and hypervisor support
45              CPU polarization.  Available modes are:
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47                     horizontal  The workload is spread across  all  available
48                                 CPUs.
49                     vertical    The workload is concentrated on few CPUs.
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51       -d, --disable cpu-list
52              Disable all specified CPUs.  Disabling a CPU means that the ker‐
53              nel sets it offline.
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55       -g, --deconfigure cpu-list
56              Deconfigure all specified CPUs.  Deconfiguring a CPU means  that
57              the  hypervisor  removes  the  CPU  from the virtual hardware on
58              which the Linux instance runs and returns it to the CPU pool.  A
59              CPU must be offline, see -d, before it can be deconfigured.
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61       -h, --help
62              Display help information and exit.
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64       -V, --version
65              Display version information and exit.
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RETURN CODES

69       chcpu has the following return codes:
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71       0      success
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73       1      failure
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75       64     partial success
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AUTHOR

78       Heiko Carstens ⟨heiko.carstens@de.ibm.com⟩
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81       Copyright IBM Corp. 2011
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SEE ALSO

84       lscpu(1)
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AVAILABILITY

87       The  chcpu  command  is part of the util-linux package and is available
88       from Linux Kernel  Archive  ⟨ftp://ftp.kernel.org/pub/linux/utils/util-
89       linux/⟩.
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93Linux                              June 2012                          CHCPU(8)
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