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<H1>CHCPU</H1>
Section: System Administration (8)<BR>Updated: July 2014<BR><A HREF="#index">Index</A>
<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
<A NAME="lbAB">&nbsp;</A>
<H2>NAME</H2>
chcpu - configure CPUs
<A NAME="lbAC">&nbsp;</A>
<H2>SYNOPSIS</H2>
<B>chcpu</B>
<B>-c</B>|<B>-d</B>|<B>-e</B>|<B>-g</B>
<I>cpu-list</I>
<BR>
<B>chcpu -p</B>
<I>mode</I>
<BR>
<B>chcpu</B>
<B>-r</B>|<B>-h</B>|<B>-V</B>
<A NAME="lbAD">&nbsp;</A>
<H2>DESCRIPTION</H2>
<B>chcpu</B>
can modify the state of CPUs. It can enable or disable CPUs, scan for new
CPUs, change the CPU dispatching
<I>mode</I>
of the underlying hypervisor, and request CPUs from the hypervisor
(configure) or return CPUs to the hypervisor (deconfigure).
<P>
Some options have a
<I>cpu-list</I>
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,
<B>0,5,7,9-11</B>
makes the command applicable to the CPUs with the addresses 0, 5, 7, 9, 10,
and 11.
<A NAME="lbAE">&nbsp;</A>
<H2>OPTIONS</H2>
<DL COMPACT>
<DT id="1"><B>-c</B>,<B> --configure </B><I>cpu-list</I>
<DD>
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.
<DT id="2"><B>-d</B>,<B> --disable </B><I>cpu-list</I>
<DD>
Disable the specified CPUs. Disabling a CPU means that the kernel sets it
offline.
<DT id="3"><B>-e</B>,<B> --enable </B><I>cpu-list</I>
<DD>
Enable the specified CPUs. Enabling a CPU means that the kernel sets it
online. A CPU must be configured, see <B>-c</B>, before it can be enabled.
<DT id="4"><B>-g</B>,<B> --deconfigure </B><I>cpu-list</I>
<DD>
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
<B>-d</B>, before it can be deconfigured.
<DT id="5"><B>-p</B>,<B> --dispatch </B><I>mode</I>
<DD>
Set the CPU dispatching
<I>mode</I>
(polarization). This option has an effect only if your hardware architecture
and hypervisor support CPU polarization. Available
<I>modes</I>
are:
<DL COMPACT><DT id="6"><DD>
<DL COMPACT>
<DT id="7">
<DD>
<B>horizontal</B>
The workload is spread across all available CPUs.
<DT id="8"><B>vertical</B>
<DD>
The workload is concentrated on few CPUs.
</DL>
</DL>
<DT id="9"><B>-r</B>,<B> --rescan</B>
<DD>
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.
<DT id="10"><B>-V</B>,<B> --version</B>
<DD>
Display version information and exit.
<DT id="11"><B>-h</B>,<B> --help</B>
<DD>
Display help text and exit.
<P>
</DL>
<A NAME="lbAF">&nbsp;</A>
<H2>RETURN CODES</H2>
<B>chcpu</B>
has the following return codes:
<DL COMPACT>
<DT id="12"><B>0</B>
<DD>
success
<DT id="13"><B>1</B>
<DD>
failure
<DT id="14"><B>64</B>
<DD>
partial success
</DL>
<A NAME="lbAG">&nbsp;</A>
<H2>AUTHOR</H2>
Heiko Carstens
<A NAME="lbAH">&nbsp;</A>
<H2>COPYRIGHT</H2>
Copyright IBM Corp. 2011
<BR>
<A NAME="lbAI">&nbsp;</A>
<H2>SEE ALSO</H2>
<B><A HREF="/cgi-bin/man/man2html?1+lscpu">lscpu</A></B>(1)
<A NAME="lbAJ">&nbsp;</A>
<H2>AVAILABILITY</H2>
The chcpu command is part of the util-linux package and is available from
Linux Kernel Archive
<P>
<HR>
<A NAME="index">&nbsp;</A><H2>Index</H2>
<DL>
<DT id="15"><A HREF="#lbAB">NAME</A><DD>
<DT id="16"><A HREF="#lbAC">SYNOPSIS</A><DD>
<DT id="17"><A HREF="#lbAD">DESCRIPTION</A><DD>
<DT id="18"><A HREF="#lbAE">OPTIONS</A><DD>
<DT id="19"><A HREF="#lbAF">RETURN CODES</A><DD>
<DT id="20"><A HREF="#lbAG">AUTHOR</A><DD>
<DT id="21"><A HREF="#lbAH">COPYRIGHT</A><DD>
<DT id="22"><A HREF="#lbAI">SEE ALSO</A><DD>
<DT id="23"><A HREF="#lbAJ">AVAILABILITY</A><DD>
</DL>
<HR>
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