147 lines
4.2 KiB
HTML
147 lines
4.2 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 CHOOM</TITLE>
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</HEAD><BODY>
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<H1>CHOOM</H1>
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Section: User Commands (1)<BR>Updated: April 2018<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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choom - display and adjust OOM-killer score.
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>choom</B>
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<B>-p</B>
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<I>pid</I>
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<P>
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<B>choom</B>
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<B>-p</B>
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<I>pid</I>
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<B>-n</B>
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<I>number</I>
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<P>
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<B>choom</B>
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<B>-n</B>
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<I>number</I>
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<I>command </I>[<I>argument</I>...]
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<P>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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The <B>choom</B> command displays and adjusts Out-Of-Memory killer score setting.
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<P>
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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="1"><B>-p</B>, <B>--pid</B> <I>pid</I>
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<DD>
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Specifies process ID.
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<DT id="2"><B>-n</B>,<B> --adjust </B><I>value</I>
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<DD>
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Specify the adjust score value.
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<DT id="3"><B>-h</B>, <B>--help</B>
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<DD>
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Display help text and exit.
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<DT id="4"><B>-V</B>, <B>--version</B>
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<DD>
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Display version information and exit.
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</DL>
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<A NAME="lbAF"> </A>
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<H2>NOTES</H2>
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Linux kernel uses the badness heuristic to select which process gets killed in
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out of memory conditions.
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<P>
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The badness heuristic assigns a value to each candidate task ranging from 0
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(never kill) to 1000 (always kill) to determine which process is targeted. The
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units are roughly a proportion along that range of allowed memory the process
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may allocate from based on an estimation of its current memory and swap use.
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For example, if a task is using all allowed memory, its badness score will be
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1000. If it is using half of its allowed memory, its score will be 500.
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<P>
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There is an additional factor included in the badness score: the current memory
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and swap usage is discounted by 3% for root processes.
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<P>
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The amount of "allowed" memory depends on the context in which the oom killer
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was called. If it is due to the memory assigned to the allocating task's cpuset
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being exhausted, the allowed memory represents the set of mems assigned to that
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cpuset. If it is due to a mempolicy's node(s) being exhausted, the allowed
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memory represents the set of mempolicy nodes. If it is due to a memory
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limit (or swap limit) being reached, the allowed memory is that configured
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limit. Finally, if it is due to the entire system being out of memory, the
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allowed memory represents all allocatable resources.
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<P>
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The adjust score value is added to the badness score before it is used to
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determine which task to kill. Acceptable values range from -1000 to +1000.
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This allows userspace to polarize the preference for oom killing either by
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always preferring a certain task or completely disabling it. The lowest
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possible value, -1000, is equivalent to disabling oom killing entirely for that
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task since it will always report a badness score of 0.
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<P>
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Setting an adjust score value of +500, for example, is roughly equivalent to
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allowing the remainder of tasks sharing the same system, cpuset, mempolicy, or
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memory controller resources to use at least 50% more memory. A value of -500,
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on the other hand, would be roughly equivalent to discounting 50% of the task's
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allowed memory from being considered as scoring against the task.
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<P>
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<A NAME="lbAG"> </A>
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<H2>AUTHORS</H2>
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<PRE>
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Karel Zak <<A HREF="mailto:kzak@redhat.com">kzak@redhat.com</A>>
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</PRE>
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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?5+proc">proc</A></B>(5)
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<A NAME="lbAI"> </A>
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<H2>AVAILABILITY</H2>
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The <B>choom</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="5"><A HREF="#lbAB">NAME</A><DD>
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<DT id="6"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="7"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="8"><A HREF="#lbAE">OPTIONS</A><DD>
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<DT id="9"><A HREF="#lbAF">NOTES</A><DD>
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<DT id="10"><A HREF="#lbAG">AUTHORS</A><DD>
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<DT id="11"><A HREF="#lbAH">SEE ALSO</A><DD>
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<DT id="12"><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: 00:05:09 GMT, March 31, 2021
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</BODY>
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</HTML>
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