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'\" t
.\" Title: chcpu
.\" Author: [see the "AUTHOR(S)" section]
.\" Generator: Asciidoctor 2.0.20
.\" Date: 2025-12-15
.\" Manual: System Administration
.\" Source: util-linux 2.41.3
.\" Language: English
.\"
.TH "CHCPU" "8" "2025-12-15" "util\-linux 2.41.3" "System Administration"
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.SH "NAME"
chcpu \- configure CPUs
.SH "SYNOPSIS"
.sp
\fBchcpu\fP \fB\-c\fP|\fB\-d\fP|\fB\-e\fP|\fB\-g\fP \fIcpu\-list\fP
.sp
\fBchcpu\fP \fB\-p\fP \fImode\fP
.sp
\fBchcpu\fP \fB\-r\fP|\fB\-h\fP|\fB\-V\fP
.SH "DESCRIPTION"
.sp
\fBchcpu\fP can modify the state of CPUs. It can enable or disable CPUs, scan for new CPUs, change the CPU dispatching \fImode\fP of the underlying hypervisor, and request CPUs from the hypervisor (configure) or return CPUs to the hypervisor (deconfigure).
.sp
Some options have a \fIcpu\-list\fP 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, \fB0,5,7,9\-11\fP makes the command applicable to the CPUs with the addresses 0, 5, 7, 9, 10, and 11.
.SH "OPTIONS"
.sp
\fB\-c\fP, \fB\-\-configure\fP \fIcpu\-list\fP
.RS 4
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.
.RE
.sp
\fB\-d\fP, \fB\-\-disable\fP \fIcpu\-list\fP
.RS 4
Disable the specified CPUs. Disabling a CPU means that the kernel sets it offline.
.RE
.sp
\fB\-e\fP, \fB\-\-enable\fP \fIcpu\-list\fP
.RS 4
Enable the specified CPUs. Enabling a CPU means that the kernel sets it online. A CPU must be configured, see \fB\-c\fP, before it can be enabled.
.RE
.sp
\fB\-g\fP, \fB\-\-deconfigure\fP \fIcpu\-list\fP
.RS 4
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 \fB\-d\fP, before it can be deconfigured.
.sp
\fBchcpu \-g\fP is not supported on IBM z/VM, CPUs are always in a configured state.
.sp
if \fBchcpu \-g\fP is supported, any \fBdisabled\fP CPUs should be \fBdeconfigured\fP to inform the hypervisor that these CPUs won\(cqt be used, avoiding potential performance penalties.
.RE
.sp
\fB\-p\fP, \fB\-\-dispatch\fP \fImode\fP
.RS 4
Set the CPU dispatching \fImode\fP (polarization). This option has an effect only if your hardware architecture and hypervisor support CPU polarization. Available \fImodes\fP are:
.sp
\fBhorizontal\fP
.RS 4
The workload is spread across all available CPUs.
.RE
.sp
\fBvertical\fP
.RS 4
The workload is concentrated on few CPUs.
.RE
.RE
.sp
\fB\-r\fP, \fB\-\-rescan\fP
.RS 4
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.
.RE
.sp
\fB\-h\fP, \fB\-\-help\fP
.RS 4
Display help text and exit.
.RE
.sp
\fB\-V\fP, \fB\-\-version\fP
.RS 4
Display version and exit.
.RE
.SH "EXIT STATUS"
.sp
\fBchcpu\fP has the following exit status values:
.sp
\fB0\fP
.RS 4
success
.RE
.sp
\fB1\fP
.RS 4
failure
.RE
.sp
\fB64\fP
.RS 4
partial success
.RE
.SH "AUTHORS"
.sp
.MTO "heiko.carstens\(atde.ibm.com" "Heiko Carstens" ""
.SH "COPYRIGHT"
.sp
Copyright IBM Corp. 2011
.SH "SEE ALSO"
.sp
\fBlscpu\fP(1)
.SH "REPORTING BUGS"
.sp
For bug reports, use the \c
.URL "https://github.com/util\-linux/util\-linux/issues" "issue tracker" "."
.SH "AVAILABILITY"
.sp
The \fBchcpu\fP command is part of the util\-linux package which can be downloaded from \c
.URL "https://www.kernel.org/pub/linux/utils/util\-linux/" "Linux Kernel Archive" "."
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