86 lines
2.5 KiB
Groff
86 lines
2.5 KiB
Groff
.TH CHCPU 8 "August 2011" Linux "User Manuals"
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.SH NAME
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chcpu \- configure CPUs
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.SH SYNOPSIS
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.B chcpu
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.BR \-e | \-d | \-c | \-g " \fIcpu-list\fP"
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.br
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.B chcpu
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.BR \-p " \fImode\fP"
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.br
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.B chcpu
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.BR \-r
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.br
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.B chcpu
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.BR \-h | \-V
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.br
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.SH DESCRIPTION
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.B chcpu
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can modify the state of CPUs. It can enable or disable CPUs, scan
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for new CPUs, change the CPU dispatching mode of the underlying hypervisor,
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and request CPUs from the hypervisor (configure) or return CPUs to the
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hypervisor (deconfigure).
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Some options have a \fIcpu-list\fP argument. Use this argument to specify a
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comma-separated list of CPUs. The list can contain individual CPU addresses or
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ranges of addresses.
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For example,
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.BR 0,5,7,9-11
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makes the command applicable to the CPUs with the addresses 0, 5, 7, 9, 10, and
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11.
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.SH OPTIONS
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.TP
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.BR \-r , " \-\-rescan"
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Trigger a rescan of CPUs. Use this option on systems that do not automatically
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detect newly attached CPUs. The Linux kernel then recognizes the new CPUs.
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.TP
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.BR \-c , " \-\-configure " \fIcpu-list\fP
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Configure all specified CPUs. Configuring a CPU means that the hypervisor takes
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a CPU from the CPU pool and assigns it to the virtual hardware on which your
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kernel runs.
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.TP
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.BR \-e , " \-\-enable " \fIcpu-list\fP
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Enable all specified CPUs. Enabling a CPU means that the kernel sets it
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online. A CPU must be configured, see -c, before it can be enabled.
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.TP
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.BR \-p , " \-\-dispatch " \fImode\fP
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Set the CPU dispatching mode (polarization). This option has an effect only if
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your hardware architecture and hypervisor support CPU polarization. There are
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two modes:
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.RS
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.TP 12
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.B horizontal
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The workload is spread across all available CPUs.
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.TP 12
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.B vertical
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The workload is concentrated on few CPUs.
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.RE
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.TP
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.BR \-d , " \-\-disable " \fIcpu-list\fP
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Disable all specified CPUs. Disabling a CPU means that the kernel sets it offline.
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.TP
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.BR \-g , " \-\-deconfigure " \fIcpu-list\fP
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Deconfigure all specified CPUs. Deconfiguring a CPU means that the hypervisor
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removes the CPU from the virtual hardware on which the Linux instance runs and
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returns it to the CPU pool. A CPU must be offline, see -d, before it can be
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deconfigured.
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.TP
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.BR \-h , " \-\-help"
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Display help information and exit.
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.TP
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.BR \-V , " \-\-version"
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Display version information and exit.
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.SH AUTHOR
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.nf
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Heiko Carstens <heiko.carstens@de.ibm.com>
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.fi
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.SH COPYRIGHT
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Copyright IBM Corp. 2011
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.br
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.SH "SEE ALSO"
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.BR lscpu (1)
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.SH AVAILABILITY
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The chcpu command is part of the util-linux package and is available from
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ftp://ftp.kernel.org/pub/linux/utils/util-linux/.
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