181 lines
5.7 KiB
HTML
181 lines
5.7 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of CHMEM</TITLE>
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</HEAD><BODY>
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<H1>CHMEM</H1>
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Section: System Administration (8)<BR>Updated: October 2016<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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chmem - configure memory
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>chmem</B>
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[<B>-h</B>] [<B>-V</B>] [<B>-v</B>] [<B>-e</B>|<B>-d</B>]
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[<I>SIZE</I>|<I>RANGE</I>|<B>-b</B> <I>BLOCKRANGE</I>]
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[-z ZONE]
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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The chmem command sets a particular size or range of memory online or offline.
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<DL COMPACT>
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<DT id="1">-<DD>
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Specify <I>SIZE</I> as <size>[m|M|g|G]. With m or M, <size> specifies the memory
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size in MiB (1024 x 1024 bytes). With g or G, <size> specifies the memory size
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in GiB (1024 x 1024 x 1024 bytes). The default unit is MiB.
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<DT id="2">-<DD>
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Specify <I>RANGE</I> in the form 0x<start>-0x<end> as shown in the output of the
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<B>lsmem</B> command. <start> is the hexadecimal address of the first byte and <end>
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is the hexadecimal address of the last byte in the memory range.
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<DT id="3">-<DD>
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Specify <I>BLOCKRANGE</I> in the form <first>-<last> or <block> as shown in the
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output of the <B>lsmem</B> command. <first> is the number of the first memory block
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and <last> is the number of the last memory block in the memory
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range. Alternatively a single block can be specified. <I>BLOCKRANGE</I> requires
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the <B>--blocks</B> option.
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<DT id="4">-<DD>
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Specify <I>ZONE</I> as the name of a memory zone, as shown in the output of the
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<B>lsmem -o +ZONES</B> command. The output shows one or more valid memory zones
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for each memory range. If multiple zones are shown, then the memory range
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currently belongs to the first zone. By default, chmem will set memory online
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to the zone Movable, if this is among the valid zones. This default can be
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changed by specifying the <B>--zone</B> option with another valid zone.
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For memory ballooning, it is recommended to select the zone Movable for memory
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online and offline, if possible. Memory in this zone is much more likely to be
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able to be offlined again, but it cannot be used for arbitrary kernel
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allocations, only for migratable pages (e.g. anonymous and page cache pages).
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Use the <B>--help</B> option to see all available zones.
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</DL>
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<P>
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<I>SIZE</I> and <I>RANGE</I> must be aligned to the Linux memory block size, as
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shown in the output of the <B>lsmem</B> command.
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<P>
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Setting memory online can fail for various reasons. On virtualized systems it
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can fail if the hypervisor does not have enough memory left, for example
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because memory was overcommitted. Setting memory offline can fail if Linux
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cannot free the memory. If only part of the requested memory can be set online
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or offline, a message tells you how much memory was set online or offline
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instead of the requested amount.
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<P>
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When setting memory online <B>chmem</B> starts with the lowest memory block
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numbers. When setting memory offline <B>chmem</B> starts with the highest memory
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block numbers.
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<A NAME="lbAE"> </A>
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<H2>OPTIONS</H2>
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<DL COMPACT>
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<DT id="5"><B>-b</B>, <B>--blocks</B>
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<DD>
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Use a <I>BLOCKRANGE</I> parameter instead of <I>RANGE</I> or <I>SIZE</I> for the
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<B>--enable</B> and <B>--disable</B> options.
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<DT id="6"><B>-d</B>, <B>--disable</B>
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<DD>
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Set the specified <I>RANGE</I>, <I>SIZE</I>, or <I>BLOCKRANGE</I> of memory offline.
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<DT id="7"><B>-e</B>, <B>--enable</B>
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<DD>
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Set the specified <I>RANGE</I>, <I>SIZE</I>, or <I>BLOCKRANGE</I> of memory online.
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<DT id="8"><B>-z</B>, <B>--zone</B>
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<DD>
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Select the memory <I>ZONE</I> where to set the specified <I>RANGE</I>, <I>SIZE</I>,
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or <I>BLOCKRANGE</I> of memory online or offline. By default, memory will be set
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online to the zone Movable, if possible.
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<DT id="9"><B>-h</B>, <B>--help</B>
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<DD>
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Print a short help text, then exit.
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<DT id="10"><B>-v</B>, <B>--verbose</B>
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<DD>
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Verbose mode. Causes <B>chmem</B> to print debugging messages about it's
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progress.
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<DT id="11"><B>-V</B>, <B>--version</B>
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<DD>
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Print the version number, then exit.
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</DL>
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<A NAME="lbAF"> </A>
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<H2>RETURN CODES</H2>
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<B>chmem</B>
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has the following return codes:
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<DL COMPACT>
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<DT id="12"><B>0</B>
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<DD>
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success
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<DT id="13"><B>1</B>
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<DD>
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failure
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<DT id="14"><B>64</B>
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<DD>
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partial success
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</DL>
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<A NAME="lbAG"> </A>
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<H2>EXAMPLES</H2>
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<DL COMPACT>
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<DT id="15"><B>chmem --enable 1024</B>
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<DD>
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This command requests 1024 MiB of memory to be set online.
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<DT id="16"><B>chmem -e 2g</B>
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<DD>
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This command requests 2 GiB of memory to be set online.
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<DT id="17"><B>chmem --disable 0x00000000e4000000-0x00000000f3ffffff</B>
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<DD>
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This command requests the memory range starting with 0x00000000e4000000
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and ending with 0x00000000f3ffffff to be set offline.
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<DT id="18"><B>chmem -b -d 10</B>
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<DD>
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This command requests the memory block number 10 to be set offline.
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</DL>
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<A NAME="lbAH"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?1+lsmem">lsmem</A></B>(1)
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<A NAME="lbAI"> </A>
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<H2>AVAILABILITY</H2>
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The <B>chmem</B> command is part of the util-linux package and is available from
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Linux Kernel Archive
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="19"><A HREF="#lbAB">NAME</A><DD>
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<DT id="20"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="21"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="22"><A HREF="#lbAE">OPTIONS</A><DD>
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<DT id="23"><A HREF="#lbAF">RETURN CODES</A><DD>
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<DT id="24"><A HREF="#lbAG">EXAMPLES</A><DD>
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<DT id="25"><A HREF="#lbAH">SEE ALSO</A><DD>
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<DT id="26"><A HREF="#lbAI">AVAILABILITY</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:06:11 GMT, March 31, 2021
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</BODY>
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</HTML>
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