sys-utils/chcpu.8

   1 .TH CHCPU 8 "July 2014" "util-linux" "System Administration"
   2 .SH NAME
   3 chcpu \- configure CPUs
   4 .SH SYNOPSIS
   5 .B chcpu
   6 .BR \-c | \-d | \-e | \-g
   7 .I cpu-list
   8 .br
   9 .B chcpu \-p
  10 .I mode
  11 .br
  12 .B chcpu
  13 .BR \-r | \-h | \-V
  14 .SH DESCRIPTION
  15 .B chcpu
  16 can modify the state of CPUs.  It can enable or disable CPUs, scan for new
  17 CPUs, change the CPU dispatching
  18 .I mode
  19 of the underlying hypervisor, and request CPUs from the hypervisor
  20 (configure) or return CPUs to the hypervisor (deconfigure).
  21 .PP
  22 Some options have a
  23 .I cpu-list
  24 argument.  Use this argument to specify a comma-separated list of CPUs.  The
  25 list can contain individual CPU addresses or ranges of addresses.  For
  26 example,
  27 .B 0,5,7,9-11
  28 makes the command applicable to the CPUs with the addresses 0, 5, 7, 9, 10,
  29 and 11.
  30 .SH OPTIONS
  31 .TP
  32 .BR \-c , " \-\-configure " \fIcpu-list\fP
  33 Configure the specified CPUs.  Configuring a CPU means that the hypervisor
  34 takes a CPU from the CPU pool and assigns it to the virtual hardware on which
  35 your kernel runs.
  36 .TP
  37 .BR \-d , " \-\-disable " \fIcpu-list\fP
  38 Disable the specified CPUs.  Disabling a CPU means that the kernel sets it
  39 offline.
  40 .TP
  41 .BR \-e , " \-\-enable " \fIcpu-list\fP
  42 Enable the specified CPUs.  Enabling a CPU means that the kernel sets it
  43 online.  A CPU must be configured, see \fB\-c\fR, before it can be enabled.
  44 .TP
  45 .BR \-g , " \-\-deconfigure " \fIcpu-list\fP
  46 Deconfigure the specified CPUs.  Deconfiguring a CPU means that the
  47 hypervisor removes the CPU from the virtual hardware on which the Linux
  48 instance runs and returns it to the CPU pool.  A CPU must be offline, see
  49 \fB\-d\fR, before it can be deconfigured.
  50 .TP
  51 .BR \-p , " \-\-dispatch " \fImode\fP
  52 Set the CPU dispatching
  53 .I mode
  54 (polarization).  This option has an effect only if your hardware architecture
  55 and hypervisor support CPU polarization.  Available
  56 .I modes
  57 are:
  58 .RS 14
  59 .TP 12
  60 .PD 0
  61 .B horizontal
  62 The workload is spread across all available CPUs.
  63 .TP 12
  64 .B vertical
  65 The workload is concentrated on few CPUs.
  66 .RE
  67 .PD 1
  68 .TP
  69 .BR \-r , " \-\-rescan"
  70 Trigger a rescan of CPUs.  After a rescan, the Linux kernel recognizes
  71 the new CPUs.  Use this option on systems that do not
  72 automatically detect newly attached CPUs.
  73 .TP
  74 .BR \-V , " \-\-version"
  75 Display version information and exit.
  76 .TP
  77 .BR \-h , " \-\-help"
  78 Display help text and exit.
  79
  80 .SH RETURN CODES
  81 .B chcpu
  82 has the following return codes:
  83 .TP
  84 .B 0
  85 success
  86 .TP
  87 .B 1
  88 failure
  89 .TP
  90 .B 64
  91 partial success
  92 .RE
  93 .SH AUTHOR
  94 .MT heiko.carstens@de.ibm.com
  95 Heiko Carstens
  96 .ME
  97 .SH COPYRIGHT
  98 Copyright IBM Corp. 2011
  99 .br
 100 .SH "SEE ALSO"
 101 .BR lscpu (1)
 102 .SH AVAILABILITY
 103 The chcpu command is part of the util-linux package and is available from
 104 .UR https://\:www.kernel.org\:/pub\:/linux\:/utils\:/util-linux/
 105 Linux Kernel Archive
 106 .UE .