-<?xml version='1.0' encoding='UTF-8'?>
-<!-- This document was created with Syntext Serna Free. -->
-<chapter xmlns="http://docbook.org/ns/docbook" xmlns:xl="http://www.w3.org/1999/xlink" version="5.0" xml:lang="en-US" xml:id="lustredebugging">
- <info>
- <title xml:id="lustredebugging.title">Lustre Debugging</title>
- </info>
- <para>This chapter describes tips and information to debug Lustre, and includes the following sections:</para>
+<?xml version='1.0' encoding='UTF-8'?><chapter xmlns="http://docbook.org/ns/docbook" xmlns:xl="http://www.w3.org/1999/xlink" version="5.0" xml:lang="en-US" xml:id="lustredebugging">
+ <title xml:id="lustredebugging.title">Debugging a Lustre File System</title>
+ <para>This chapter describes tips and information to debug a Lustre file system, and includes the
+ following sections:</para>
<itemizedlist>
<listitem>
<para><xref linkend="dbdoclet.50438274_15874"/></para>
</listitem>
</itemizedlist>
<section xml:id="dbdoclet.50438274_15874">
- <title>28.1 Diagnostic and Debugging Tools</title>
+ <title><indexterm><primary>debugging</primary></indexterm>
+Diagnostic and Debugging Tools</title>
<para>A variety of diagnostic and analysis tools are available to debug issues with the Lustre software. Some of these are provided in Linux distributions, while others have been developed and are made available by the Lustre project.</para>
- <section remap="h3">
- <title>28.1.1 Lustre Debugging Tools</title>
- <para>The following in-kernel debug mechanisms are incorporated into the Lustre software:</para>
+ <section remap="h3" xml:id="section_dms_q21_kk">
+ <title><indexterm>
+ <primary>debugging</primary>
+ <secondary>tools</secondary>
+ </indexterm> Lustre Debugging Tools</title>
+ <para>The following in-kernel debug mechanisms are incorporated into the Lustre
+ software:</para>
<itemizedlist>
<listitem>
- <para><emphasis role="bold">Debug logs</emphasis> - A circular debug buffer to which Lustre internal debug messages are written (in contrast to error messages, which are printed to the syslog or console). Entries to the Lustre debug log are controlled by the mask set by <literal>/proc/sys/lnet/debug</literal>. The log size defaults to 5 MB per CPU but can be increased as a busy system will quickly overwrite 5 MB. When the buffer fills, the oldest information is discarded.</para>
+ <para xml:id="para_fkj_rld_hk"><emphasis role="bold">Debug logs</emphasis> - A circular
+ debug buffer to which Lustre internal debug messages are written (in contrast to error
+ messages, which are printed to the syslog or console). Entries to the Lustre debug log
+ are controlled by the mask set by <literal>/proc/sys/lnet/debug</literal>. The log size
+ defaults to 5 MB per CPU but can be increased as a busy system will quickly overwrite 5
+ MB. When the buffer fills, the oldest information is discarded.</para>
</listitem>
<listitem>
- <para><emphasis role="bold">Debug daemon</emphasis> - The debug daemon controls logging of debug messages.</para>
+ <para><emphasis role="bold">Debug daemon</emphasis> - The debug daemon controls logging of
+ debug messages.</para>
</listitem>
<listitem>
<para><emphasis role="bold">
<literal>/proc/sys/lnet/debug</literal>
- </emphasis> - This file contains a mask that can be used to delimit the debugging information written out to the kernel debug logs.</para>
+ </emphasis> - This file contains a mask that can be used to delimit the debugging
+ information written out to the kernel debug logs.</para>
</listitem>
</itemizedlist>
<para>The following tools are also provided with the Lustre software:</para>
<listitem>
<para><emphasis role="bold">
<literal>lctl</literal>
- </emphasis> - This tool is used with the debug_kernel option to manually dump the Lustre debugging log or post-process debugging logs that are dumped automatically. For more information about the lctl tool, see <xref linkend="dbdoclet.50438274_62472"/> and <xref linkend="dbdoclet.50438219_38274"/>.</para>
+ </emphasis> - This tool is used with the debug_kernel option to manually dump the Lustre
+ debugging log or post-process debugging logs that are dumped automatically. For more
+ information about the lctl tool, see <xref linkend="dbdoclet.50438274_62472"/> and <xref
+ linkend="dbdoclet.50438219_38274"/>.</para>
</listitem>
<listitem>
- <para><replaceable role="bold">Lustre subsystem asserts</replaceable> - A panic-style assertion (LBUG) in the kernel causes Lustre to dump the debug log to the file <literal>/tmp/lustre-log.<replaceable><timestamp></replaceable></literal> where it can be retrieved after a reboot. For more information, see <xref linkend="dbdoclet.50438198_40669"/>.</para>
+ <para>Lustre subsystem asserts - A panic-style assertion (LBUG) in the kernel causes the
+ Lustre file system to dump the debug log to the file
+ <literal>/tmp/lustre-log.<replaceable>timestamp</replaceable></literal> where it can
+ be retrieved after a reboot. For more information, see <xref
+ linkend="dbdoclet.50438198_40669"/>.</para>
</listitem>
<listitem>
<para>
- <literal><replaceable>lfs</replaceable></literal>
- - This utility provides access to the extended attributes (EAs) of a Lustre file (along with other information). For more inforamtion about lfs, see <xref linkend="dbdoclet.50438206_94597"/>.</para>
+ <literal>
+ <replaceable>lfs</replaceable>
+ </literal> - This utility provides access to the extended attributes (EAs) of a Lustre
+ file (along with other information). For more information about lfs, see <xref
+ linkend="dbdoclet.50438206_94597"/>.</para>
</listitem>
</itemizedlist>
</section>
<section remap="h3">
- <title>28.1.2 External Debugging Tools</title>
+ <title><indexterm><primary>debugging</primary><secondary>external tools</secondary></indexterm>External Debugging Tools</title>
<para>The tools described in this section are provided in the Linux kernel or are available at an external website. For information about using some of these tools for Lustre debugging, see <xref linkend="dbdoclet.50438274_23607"/> and <xref linkend="dbdoclet.50438274_80443"/>.</para>
<section remap="h4">
- <title>28.1.2.1 Tools for Administrators and Developers</title>
- <para>Some general debugging tools provided as a part of the standard Linux distro are:</para>
+ <title><indexterm><primary>debugging</primary><secondary>admin tools</secondary></indexterm>Tools for Administrators and Developers</title>
+ <para>Some general debugging tools provided as a part of the standard Linux distribution
+ are:</para>
<itemizedlist>
<listitem>
<para><emphasis role="bold">
</emphasis> . <literal>syslogd</literal> prints fatal or serious messages at this log.</para>
</listitem>
<listitem>
- <para><emphasis role="bold">Crash dumps</emphasis> . On crash-dump enabled kernels, sysrq c produces a crash dump. Lustre enhances this crash dump with a log dump (the last 64 KB of the log) to the console.</para>
+ <para><emphasis role="bold">Crash dumps</emphasis> . On crash-dump enabled kernels,
+ sysrq c produces a crash dump. The Lustre software enhances this crash dump with a log
+ dump (the last 64 KB of the log) to the console.</para>
</listitem>
<listitem>
<para><emphasis role="bold">
<listitem>
<para><emphasis role="bold">
<literal>netdump</literal>
- </emphasis>. A crash dump utility from Red Hat that allows memory images to be dumped over a network to a central server for analysis. The <literal>netdump</literal> utility was replaced by <literal>kdump</literal> in RHEL 5. For more information about <literal>netdump</literal>, see <link xl:href="http://www.redhat.com/support/wpapers/redhat/netdump/">Red Hat, Inc.'s Network Console and Crash Dump Facility</link>.</para>
+ </emphasis>. A crash dump utility from Red Hat that allows memory images to be dumped
+ over a network to a central server for analysis. The <literal>netdump</literal>
+ utility was replaced by <literal>kdump</literal> in Red Hat Enterprise Linux 5. For
+ more information about <literal>netdump</literal>, see <link
+ xl:href="http://www.redhat.com/support/wpapers/redhat/netdump/">Red Hat, Inc.'s
+ Network Console and Crash Dump Facility</link>.</para>
</listitem>
+ <listitem>
+ <para><emphasis><literal>wireshark</literal> </emphasis> . A network
+ packet inspection tool that allows debugging of information that was
+ sent between the various Lustre nodes. This tool is built on top of
+ <literal>tcpdump</literal> and can read packet dumps generated by
+ it. There are plug-ins available to dissassemble the LNet and
+ Lustre protocols. They are located within the <link
+ xl:href="http://git.hpdd.intel.com/">Lustre git repository</link>
+ under <literal>lustre/contrib/wireshark/</literal>. Installation
+ instruction are included in that directory. See also <link
+ xl:href="http://www.wireshark.org/">Wireshark Website</link> for
+ more details.</para>
+ </listitem>
</itemizedlist>
</section>
<section remap="h4">
- <title>28.1.2.2 Tools for Developers</title>
- <para>The tools described in this section may be useful for debugging Lustre in a development environment.</para>
+ <title><indexterm><primary>debugging</primary><secondary>developer tools</secondary></indexterm>Tools for Developers</title>
+ <para>The tools described in this section may be useful for debugging a Lustre file system
+ in a development environment.</para>
<para>Of general interest is:</para>
<itemizedlist>
<listitem>
<para><literal>
- <replaceable role="bold">leak_finder.pl</replaceable>
- </literal> . This program provided with Lustre is useful for finding memory leaks in the code.</para>
+ <replaceable>leak_finder.pl</replaceable>
+ </literal> . This program provided with the Lustre software is useful for finding
+ memory leaks in the code.</para>
</listitem>
</itemizedlist>
<para>A virtual machine is often used to create an isolated development and test environment. Some commonly-used virtual machines are:</para>
</section>
</section>
<section xml:id="dbdoclet.50438274_23607">
- <title>28.2 Lustre Debugging Procedures</title>
+ <title><indexterm><primary>debugging</primary><secondary>procedure</secondary></indexterm>Lustre Debugging Procedures</title>
<para>The procedures below may be useful to administrators or developers debugging a Lustre files system.</para>
<section remap="h3">
- <title>28.2.1 Understanding the Lustre Debug Messaging Format</title>
- <para>Lustre debug messages are categorized by originating sybsystem, message type, and locaton in the source code. For a list of subsystems and message types, see <xref linkend="dbdoclet.50438274_57603"/>.</para>
+ <title><indexterm><primary>debugging</primary><secondary>message format</secondary></indexterm>Understanding the Lustre Debug Messaging Format</title>
+ <para>Lustre debug messages are categorized by originating subsystem, message type, and location in the source code. For a list of subsystems and message types, see <xref linkend="dbdoclet.50438274_57603"/>.</para>
<note>
- <para>For a current list of subsystems and debug message types, see <literal>lnet/include/libcfs/libcfs.h</literal> in the Lustre tree</para>
+ <para>For a current list of subsystems and debug message types, see
+ <literal>libcfs/include/libcfs/libcfs_debug.h</literal> in the Lustre software
+ tree</para>
</note>
<para>The elements of a Lustre debug message are described in <xref linkend="dbdoclet.50438274_57177"/> Format of Lustre Debug Messages.</para>
<section xml:id="dbdoclet.50438274_57603">
- <title>28.2.1.1 Lustre Debug Messages</title>
- <para>Each Lustre debug message has the tag of the subsystem it originated in, the message type, and the location in the source code. The subsystems and debug types used in Lustre are as follows:</para>
+ <title>Lustre Debug Messages</title>
+ <para>Each Lustre debug message has the tag of the subsystem it originated in, the message
+ type, and the location in the source code. The subsystems and debug types used are as
+ follows:</para>
<itemizedlist>
<listitem>
<para> Standard Subsystems:</para>
</itemizedlist>
</section>
<section xml:id="dbdoclet.50438274_57177">
- <title>28.2.1.2 Format of Lustre Debug Messages</title>
- <para>Lustre uses the <literal>CDEBUG</literal> and <literal>CERROR</literal> macros to print the debug or error messages. To print the message, the <literal>CDEBUG</literal> macro uses <literal>portals_debug_msg</literal> (<literal>portals/linux/oslib/debug.c</literal>). The message format is described below, along with an example.</para>
+ <title>Format of Lustre Debug Messages</title>
+ <para>The Lustre software uses the <literal>CDEBUG()</literal> and
+ <literal>CERROR()</literal> macros to print the debug or error messages. To print the
+ message, the <literal>CDEBUG()</literal> macro uses the function
+ <literal>libcfs_debug_msg()</literal> (<literal>libcfs/libcfs/tracefile.c</literal>).
+ The message format is described below, along with an example.</para>
<informaltable frame="all">
<tgroup cols="2">
<colspec colname="c1" colwidth="50*"/>
<thead>
<row>
<entry>
- <para><emphasis role="bold">Parameter</emphasis></para>
+ <para><emphasis role="bold">Description</emphasis></para>
</entry>
<entry>
- <para><emphasis role="bold">Description</emphasis></para>
+ <para><emphasis role="bold">Parameter</emphasis></para>
</entry>
</row>
</thead>
</row>
<row>
<entry>
- <para> <emphasis role="bold">sec.used</emphasis></para>
+ <para> <emphasis role="bold">seconds.microseconds</emphasis></para>
</entry>
<entry>
- <para> 10818808</para>
- <para> 47.677302</para>
+ <para> 1081880847.677302</para>
</entry>
</row>
<row>
<para> <emphasis role="bold">stack size</emphasis></para>
</entry>
<entry>
- <para> 1204:</para>
+ <para> 1204</para>
</entry>
</row>
<row>
<para> <emphasis role="bold">pid</emphasis></para>
</entry>
<entry>
- <para> 2973:</para>
+ <para> 2973</para>
</entry>
</row>
<row>
<entry>
- <para> <emphasis role="bold">host pid (if uml) or zero</emphasis></para>
+ <para> <emphasis role="bold">host pid (UML only) or zero</emphasis></para>
</entry>
<entry>
- <para> 31070:</para>
+ <para> 31070</para>
</entry>
</row>
<row>
<entry>
- <para> <emphasis role="bold">(file:line #:functional())</emphasis></para>
+ <para> <emphasis role="bold">(file:line #:function_name())</emphasis></para>
</entry>
<entry>
- <para> (as_dev.c:144:create_write_buffers())</para>
+ <para> (obd_mount.c:2089:lustre_fill_super())</para>
</entry>
</row>
<row>
</informaltable>
</section>
<section remap="h4">
- <title>28.2.1.3 Lustre Debug Messages Buffer</title>
- <para>Lustre debug messages are maintained in a buffer, with the maximum buffer size specified (in MBs) by the <literal>debug_mb</literal> parameter (<literal>/proc/sys/lnet/debug_mb</literal>). The buffer is circular, so debug messages are kept until the allocated buffer limit is reached, and then the first messages are overwritten.</para>
+ <title>Lustre Debug Messages Buffer</title>
+ <para>Lustre debug messages are maintained in a buffer, with the maximum buffer size specified (in MBs) by the <literal>debug_mb</literal> parameter (<literal>lctl get_param debug_mb</literal>). The buffer is circular, so debug messages are kept until the allocated buffer limit is reached, and then the first messages are overwritten.</para>
</section>
</section>
- <section xml:id='dbdoclet.50438274_62472'>
- <title>28.2.2 Using the lctl Tool to View Debug Messages</title>
+ <section xml:id="dbdoclet.50438274_62472">
+ <title><indexterm><primary>debugging</primary><secondary>using lctl</secondary></indexterm>Using the lctl Tool to View Debug Messages</title>
<para>The <literal>lctl</literal> tool allows debug messages to be filtered based on subsystems and message types to extract information useful for troubleshooting from a kernel debug log. For a command reference, see <xref linkend="dbdoclet.50438219_38274"/>.</para>
<para>You can use <literal>lctl</literal> to:</para>
<itemizedlist>
<listitem>
<para>Obtain a list of all the types and subsystems:</para>
- <screen>lctl > debug_list <emphasis><subs | types></emphasis></screen>
+ <screen>lctl > debug_list <replaceable>subsystems|types</replaceable></screen>
</listitem>
</itemizedlist>
<itemizedlist>
<listitem>
<para>Filter the debug log:</para>
- <screen>lctl > filter <emphasis><subsystem name | debug type></emphasis></screen>
+ <screen>lctl > filter <replaceable>subsystem_name|debug_type</replaceable></screen>
</listitem>
</itemizedlist>
<note>
<itemizedlist>
<listitem>
<para>Show debug messages belonging to certain subsystem or type:</para>
- <screen>lctl > show <emphasis><subsystem name | debug type></emphasis></screen>
+ <screen>lctl > show <replaceable>subsystem_name|debug_type</replaceable></screen>
<para><literal>debug_kernel</literal> pulls the data from the kernel logs, filters it appropriately, and displays or saves it as per the specified options</para>
- <screen>lctl > debug_kernel [<emphasis>output filename</emphasis>]</screen>
+ <screen>lctl > debug_kernel [<replaceable>output filename</replaceable>]</screen>
<para>If the debugging is being done on User Mode Linux (UML), it might be useful to save the logs on the host machine so that they can be used at a later time.</para>
</listitem>
</itemizedlist>
<itemizedlist>
<listitem>
<para>Filter a log on disk, if you already have a debug log saved to disk (likely from a crash):</para>
- <screen>lctl > debug_file <emphasis><input filename></emphasis> [<emphasis>output filename</emphasis>] </screen>
+ <screen>lctl > debug_file <replaceable>input_file</replaceable> [<replaceable>output_file</replaceable>] </screen>
<para>During the debug session, you can add markers or breaks to the log for any reason:</para>
<screen>lctl > mark [marker text] </screen>
<para>The marker text defaults to the current date and time in the debug log (similar to the example shown below):</para>
<para>Debug messages displayed with <literal>lctl</literal> are also subject to the kernel debug masks; the filters are additive.</para>
</note>
<section remap="h4">
- <title>28.2.2.1 Sample <literal>lctl</literal> Run</title>
+ <title><indexterm><primary>debugging</primary><secondary>lctl example</secondary></indexterm>Sample <literal>lctl</literal> Run</title>
<para>Below is a sample run using the <literal>lctl</literal> command.</para>
<screen>bash-2.04# ./lctl
lctl > debug_kernel /tmp/lustre_logs/log_all
</section>
</section>
<section remap="h3">
- <title>28.2.3 Dumping the Buffer to a File (<literal>debug_daemon</literal>)</title>
- <para>The <literal>debug_daemon</literal> option is used by <literal>lctl</literal> to control the dumping of the <literal>debug_kernel</literal> buffer to a user-specified file. This functionality uses a kernel thread on top of <literal>debug_kernel</literal>, which works in parallel with the <literal>debug_daemon</literal> command.</para>
- <para>The <literal>debug_daemon</literal> is highly dependent on file system write speed. File system write operations may not be fast enough to flush out all of the <literal>debug_buffer</literal> if the Lustre file system is under heavy system load and continues to <literal>CDEBUG</literal> to the <literal>debug_buffer</literal>. The <literal>debug_daemon</literal> will write the message <literal>DEBUG MARKER:</literal> Trace buffer full into the <literal>debug_buffer</literal> to indicate the <literal>debug_buffer</literal> contents are overlapping before the <literal>debug_daemon</literal> flushes data to a file.</para>
- <para>Users can use <literal>lctl control</literal> to start or stop the Lustre daemon from dumping the <literal>debug_buffe</literal>r to a file. Users can also temporarily hold daemon from dumping the file. Use of the <literal>debug_daemon</literal> sub-command to <literal>lctl</literal> can provide the same function.</para>
+ <title>Dumping the Buffer to a File (<literal>debug_daemon</literal>)</title>
+ <para>The <literal>lctl debug_daemon</literal> command is used to continuously dump the <literal>debug_kernel</literal> buffer to a user-specified file. This functionality uses a kernel thread to continuously dump the messages from the kernel debug log, so that much larger debug logs can be saved over a longer time than would fit in the kernel ringbuffer.</para>
+ <para>The <literal>debug_daemon</literal> is highly dependent on file system write speed. File system write operations may not be fast enough to flush out all of the <literal>debug_buffer</literal> if the Lustre file system is under heavy system load and continues to log debug messages to the <literal>debug_buffer</literal>. The <literal>debug_daemon</literal> will write the message <literal>DEBUG MARKER: Trace buffer full</literal> into the <literal>debug_buffer</literal> to indicate the <literal>debug_buffer</literal> contents are overlapping before the <literal>debug_daemon</literal> flushes data to a file.</para>
+ <para>Users can use the <literal>lctl debug_daemon</literal> command to start or stop the Lustre daemon from dumping the <literal>debug_buffer</literal> to a file.</para>
<section remap="h4">
- <title>28.2.3.1 <literal>lctl debug_daemon</literal> Commands</title>
- <para>This section describes <literal>lctl debug_daemon</literal> commands.</para>
- <para>To initiate the <literal>debug_daemon</literal> to start dumping <literal>debug_buffer</literal> into a file., enter</para>
- <screen>$ lctl debug_daemon start [{file} {megabytes}]</screen>
- <para>The file can be a system default file, as shown in <literal>/proc/sys/lnet/debug_path</literal>. After Lustre starts, the default path is <literal>/tmp/lustre-log-$HOSTNAME</literal>. Users can specify a new filename for <literal>debug_daemon</literal> to output <literal>debug_buffer</literal>. The new file name shows up in <literal>/proc/sys/lnet/debug_path</literal>. Megabytes is the limitation of the file size in MBs.</para>
- <para>The daemon wraps around and dumps data to the beginning of the file when the output file size is over the limit of the user-specified file size. To decode the dumped file to ASCII and order the log entries by time, run:</para>
- <screen>lctl debug_file {file} > {newfile}</screen>
- <para>The output is internally sorted by the <literal>lct</literal>l command using quicksort.</para>
- <para>To completely shut down the <literal>debug_daemon</literal> operation and flush the file output, enter:</para>
- <screen>debug_daemon stop</screen>
+ <title><literal>lctl debug_daemon</literal> Commands</title>
+ <para>To initiate the <literal>debug_daemon</literal> to start dumping the <literal>debug_buffer</literal> into a file, run as the root user:</para>
+ <screen>lctl debug_daemon start <replaceable>filename</replaceable> [<replaceable>megabytes</replaceable>]</screen>
+ <para>The debug log will be written to the specified filename from the kernel. The file will be limited to the optionally specified number of megabytes.</para>
+ <para>The daemon wraps around and dumps data to the beginning of the file when the output file size is over the limit of the user-specified file size. To decode the dumped file to ASCII and sort the log entries by time, run:</para>
+ <screen>lctl debug_file <replaceable>filename</replaceable> > <replaceable>newfile</replaceable></screen>
+ <para>The output is internally sorted by the <literal>lctl</literal> command.</para>
+ <para>To stop the <literal>debug_daemon</literal> operation and flush the file output, run:</para>
+ <screen>lctl debug_daemon stop</screen>
<para>Otherwise, <literal>debug_daemon</literal> is shut down as part of the Lustre file system shutdown process. Users can restart <literal>debug_daemon</literal> by using start command after each stop command issued.</para>
- <para>This is an example using <literal>debug_daemon</literal> with the interactive mode of <literal>lctl</literal> to dump debug logs to a 10 MB file.</para>
- <screen>#~/utils/lctl</screen>
- <para>To start the daemon to dump debug_buffer into a 40 MB <literal>/tmp/dump</literal> file, enter:</para>
- <screen>lctl > debug_daemon start /trace/log 40 </screen>
- <para>To completely shut down the daemon, enter:</para>
+ <para>This is an example using <literal>debug_daemon</literal> with the interactive mode of <literal>lctl</literal> to dump debug logs to a 40 MB file.</para>
+ <screen>lctl</screen>
+ <screen>lctl > debug_daemon start /var/log/lustre.40.bin 40 </screen>
+ <screen><replaceable>run filesystem operations to debug</replaceable></screen>
<screen>lctl > debug_daemon stop </screen>
- <para>To start another daemon with an unlimited file size, enter:</para>
- <screen>lctl > debug_daemon start /tmp/unlimited </screen>
+ <screen>lctl > debug_file /var/log/lustre.bin /var/log/lustre.log</screen>
+ <para>To start another daemon with an unlimited file size, run:</para>
+ <screen>lctl > debug_daemon start /var/log/lustre.bin </screen>
<para>The text message <literal>*** End of debug_daemon trace log ***</literal> appears at the end of each output file.</para>
</section>
</section>
<section remap="h3">
- <title>28.2.4 Controlling Information Written to the Kernel Debug Log</title>
- <para>Masks are provided in <literal>/proc/sys/lnet/subsystem_debug</literal> and <literal>/proc/sys/lnet/debug</literal> to be used with the systctl command to determine what information is to be written to the debug log. The subsystem_debug mask determines the information written to the log based on the subsystem (such as iobdfilter, net, portals, or OSC). The debug mask controls information based on debug type (such as info, error, trace, or alloc).</para>
+ <title><indexterm><primary>debugging</primary><secondary>kernel debug log</secondary></indexterm>Controlling Information Written to the Kernel Debug Log</title>
+ <para>The <literal>lctl set_param subsystem_debug=<replaceable>subsystem_mask</replaceable></literal> and <literal>lctl set_param debug=<replaceable>debug_mask</replaceable></literal> are used to determine which information is written to the debug log. The subsystem_debug mask determines the information written to the log based on the functional area of the code (such as lnet, osc, or ldlm). The debug mask controls information based on the message type (such as info, error, trace, or malloc). For a complete list of possible debug masks use the <literal>lctl debug_list types</literal> command.</para>
<para>To turn off Lustre debugging completely:</para>
- <screen>sysctl -w lnet.debug=0 </screen>
+ <screen>lctl set_param debug=0 </screen>
<para>To turn on full Lustre debugging:</para>
- <screen>sysctl -w lnet.debug=-1 </screen>
- <para>To turn on logging of messages related to network communications:</para>
- <screen>sysctl -w lnet.debug=net </screen>
+ <screen>lctl set_param debug=-1 </screen>
+ <para>To list all possible debug masks:</para>
+ <screen>lctl debug_list types</screen>
+ <para>To log only messages related to network communications:</para>
+ <screen>lctl set_param debug=net </screen>
<para>To turn on logging of messages related to network communications and existing debug flags:</para>
- <screen>sysctl -w lnet.debug=+net </screen>
+ <screen>lctl set_param debug=+net </screen>
<para>To turn off network logging with changing existing flags:</para>
- <screen>sysctl -w lnet.debug=-net </screen>
- <para>The various options available to print to kernel debug logs are listed in <literal>lnet/include/libcfs/libcfs.h</literal></para>
+ <screen>lctl set_param debug=-net </screen>
+ <para>The various options available to print to kernel debug logs are listed in <literal>libcfs/include/libcfs/libcfs.h</literal></para>
</section>
<section remap="h3">
- <title>28.2.5 Troubleshooting with <literal>strace</literal></title>
+ <title><indexterm><primary>debugging</primary><secondary>using strace</secondary></indexterm>Troubleshooting with <literal>strace</literal></title>
<para>The <literal>strace</literal> utility provided with the Linux distribution enables system calls to be traced by intercepting all the system calls made by a process and recording the system call name, arguments, and return values.</para>
<para>To invoke <literal>strace</literal> on a program, enter:</para>
- <screen>$ strace <emphasis><program> <args></emphasis> </screen>
+ <screen>$ strace <replaceable>program</replaceable> <replaceable>[arguments]</replaceable> </screen>
<para>Sometimes, a system call may fork child processes. In this situation, use the <literal>-f</literal> option of <literal>strace</literal> to trace the child processes:</para>
- <screen>$ strace -f <emphasis><program> <args></emphasis> </screen>
+ <screen>$ strace -f <replaceable>program</replaceable> <replaceable>[arguments]</replaceable> </screen>
<para>To redirect the <literal>strace</literal> output to a file, enter:</para>
- <screen>$ strace -o <emphasis><filename> <program> <args></emphasis> </screen>
+ <screen>$ strace -o <replaceable>filename</replaceable> <replaceable>program</replaceable> <replaceable>[arguments]</replaceable> </screen>
<para>Use the <literal>-ff</literal> option, along with <literal>-o</literal>, to save the trace output in <literal>filename.pid</literal>, where <literal>pid</literal> is the process ID of the process being traced. Use the <literal>-ttt</literal> option to timestamp all lines in the strace output, so they can be correlated to operations in the lustre kernel debug log.</para>
- <para>If the debugging is done in UML, save the traces on the host machine. In this example, <literal>hostfs</literal> is mounted on <literal>/r</literal>:</para>
- <screen>$ strace -o /r/tmp/vi.strace </screen>
</section>
<section remap="h3">
- <title>28.2.6 Looking at Disk Content</title>
- <para>In Lustre, the inodes on the metadata server contain extended attributes (EAs) that store information about file striping. EAs contain a list of all object IDs and their locations (that is, the OST that stores them). The <literal>lfs</literal> tool can be used to obtain this information for a given file using the <literal>getstripe</literal> subcommand. Use a corresponding <literal>lfs setstripe</literal> command to specify striping attributes for a new file or directory.</para>
- <para>The <literal>lfs getstripe</literal> utility is written in C; it takes a Lustre filename as input and lists all the objects that form a part of this file. To obtain this information for the file <literal>/mnt/lustre/frog</literal> in Lustre file system, run:</para>
- <screen>$ lfs getstripe /mnt/lustre/frog
-$
- obdix objid
- 0 17
- 1 4
-</screen>
- <para>The <literal>debugfs</literal> tool is provided in the <literal>e2fsprogs</literal> package. It can be used for interactive debugging of an <literal>ldiskfs</literal> file system. The <literal>debugfs</literal> tool can either be used to check status or modify information in the file system. In Lustre, all objects that belong to a file are stored in an underlying <literal>ldiskfs</literal> file system on the OSTs. The file system uses the object IDs as the file names. Once the object IDs are known, use the <literal>debugfs</literal> tool to obtain the attributes of all objects from different OSTs.</para>
- <para>A sample run for the <literal>/mnt/lustre/frog</literal> file used in the above example is shown here:</para>
- <screen> $ debugfs -c /tmp/ost1
- debugfs: cd O
- debugfs: cd 0 /* for files in group 0 */
- debugfs: cd d<objid % 32>
- debugfs: stat <objid> /* for getattr on object */
- debugfs: quit
-## Suppose object id is 36, then follow the steps below:
- $ debugfs /tmp/ost1
- debugfs: cd O
- debugfs: cd 0
- debugfs: cd d4 /* objid % 32 */
- debugfs: stat 36 /* for getattr on obj 4*/
- debugfs: dump 36 /tmp/obj.36 /* dump contents of obj 4 */
- debugfs: quit</screen>
+ <title><indexterm><primary>debugging</primary><secondary>disk contents</secondary></indexterm>Looking at Disk Content</title>
+ <para>In a Lustre file system, the inodes on the metadata server contain extended attributes
+ (EAs) that store information about file striping. EAs contain a list of all object IDs and
+ their locations (that is, the OST that stores them). The <literal>lfs</literal> tool can be
+ used to obtain this information for a given file using the <literal>getstripe</literal>
+ subcommand. Use a corresponding <literal>lfs setstripe</literal> command to specify striping
+ attributes for a new file or directory.</para>
+ <para>The <literal>lfs getstripe</literal> command takes a Lustre filename as input and lists
+ all the objects that form a part of this file. To obtain this information for the file
+ <literal>/mnt/testfs/frog</literal> in a Lustre file system, run:</para>
+ <screen>$ lfs getstripe /mnt/testfs/frog
+lmm_stripe_count: 2
+lmm_stripe_size: 1048576
+lmm_pattern: 1
+lmm_layout_gen: 0
+lmm_stripe_offset: 2
+ obdidx objid objid group
+ 2 818855 0xc7ea7 0
+ 0 873123 0xd52a3 0
+ </screen>
+ <para>The <literal>debugfs</literal> tool is provided in the
+ <literal>e2fsprogs</literal> package. It can be used for interactive
+ debugging of an <literal>ldiskfs</literal> file system. The
+ <literal>debugfs</literal> tool can either be used to check status or
+ modify information in the file system. In a Lustre file system, all
+ objects that belong to a file are stored in an underlying
+ <literal>ldiskfs</literal> file system on the OSTs. The file system
+ uses the object IDs as the file names. Once the object IDs are known,
+ use the <literal>debugfs</literal> tool to obtain the attributes of
+ all objects from different OSTs.</para>
+ <para>A sample run for the <literal>/mnt/testfs/frog</literal> file used
+ in the above example is shown here:</para>
+ <screen>$ debugfs -c -R "stat O/0/d$((818855 % 32))/818855" /dev/vgmyth/lvmythost2
+
+debugfs 1.41.90.wc3 (28-May-2011)
+/dev/vgmyth/lvmythost2: catastrophic mode - not reading inode or group bitmaps
+Inode: 227649 Type: regular Mode: 0666 Flags: 0x80000
+Generation: 1375019198 Version: 0x0000002f:0000728f
+User: 1000 Group: 1000 Size: 2800
+File ACL: 0 Directory ACL: 0
+Links: 1 Blockcount: 8
+Fragment: Address: 0 Number: 0 Size: 0
+ ctime: 0x4e177fe5:00000000 -- Fri Jul 8 16:08:37 2011
+ atime: 0x4d2e2397:00000000 -- Wed Jan 12 14:56:39 2011
+ mtime: 0x4e177fe5:00000000 -- Fri Jul 8 16:08:37 2011
+crtime: 0x4c3b5820:a364117c -- Mon Jul 12 12:00:00 2010
+Size of extra inode fields: 28
+Extended attributes stored in inode body:
+ fid = "08 80 24 00 00 00 00 00 28 8a e7 fc 00 00 00 00 a7 7e 0c 00 00 00 00 00
+ 00 00 00 00 00 00 00 00 " (32)
+ fid: objid=818855 seq=0 parent=[0x248008:0xfce78a28:0x0] stripe=0
+EXTENTS:
+(0):63331288
+ </screen>
</section>
<section remap="h3">
- <title>28.2.7 Finding the Lustre UUID of an OST</title>
- <para>To determine the Lustre UUID of an obdfilter disk (for example, if you mix up the cables on your OST devices or the SCSI bus numbering suddenly changes and the SCSI devices get new names), use <literal>debugfs</literal> to get the <literal>last_rcvd</literal> file.</para>
+ <title>Finding the Lustre UUID of an OST</title>
+ <para>To determine the Lustre UUID of an OST disk (for example, if you mix up the cables on your OST devices or the SCSI bus numbering suddenly changes and the SCSI devices get new names), it is possible to extract this from the last_rcvd file using debugfs:</para>
+ <screen>debugfs -c -R "dump last_rcvd /tmp/last_rcvd" /dev/sdc
+strings /tmp/last_rcvd | head -1
+myth-OST0004_UUID
+ </screen>
+ <para>It is also possible (and easier) to extract this from the file system label using the
+ <literal>dumpe2fs</literal> command:</para>
+ <screen>dumpe2fs -h /dev/sdc | grep volume
+dumpe2fs 1.41.90.wc3 (28-May-2011)
+Filesystem volume name: myth-OST0004
+ </screen>
+ <para>The debugfs and dumpe2fs commands are well documented in the <literal>debugfs(8)</literal> and <literal>dumpe2fs(8)</literal> manual pages.</para>
</section>
<section remap="h3">
- <title>28.2.8 Printing Debug Messages to the Console</title>
+ <title>Printing Debug Messages to the Console</title>
<para>To dump debug messages to the console (<literal>/var/log/messages</literal>), set the corresponding debug mask in the <literal>printk</literal> flag:</para>
- <screen>sysctl -w lnet.printk=-1 </screen>
- <para>This slows down the system dramatically. It is also possible to selectively enable or disable this capability for particular flags using:</para>
- <screen>sysctl -w lnet.printk=+vfstrace
-sysctl -w lnet.printk=-vfstrace </screen>
- <para>It is possible to disable warning, error, and console messages, though it is strongly recommended to have something like <literal>lctl debug_daemon</literal> running to capture this data to a local file system for debugging purposes.</para>
+ <screen>lctl set_param printk=-1 </screen>
+ <para>This slows down the system dramatically. It is also possible to selectively enable or disable this capability for particular flags using:<literal>lctl set_param printk=+vfstrace</literal> and <literal>lctl set_param printk=-vfstrace </literal>.</para>
+ <para>It is possible to disable warning, error, and console messages, though it is strongly recommended to have something like <literal>lctl debug_daemon</literal> running to capture this data to a local file system for failure detection purposes.</para>
</section>
<section remap="h3">
- <title>28.2.9 Tracing Lock Traffic</title>
- <para>Lustre has a specific debug type category for tracing lock traffic. Use:</para>
+ <title>Tracing Lock Traffic</title>
+ <para>The Lustre software provides a specific debug type category for tracing lock traffic.
+ Use:</para>
<screen>lctl> filter all_types
lctl> show dlmtrace
-lctl> debug_kernel [filename] </screen>
+lctl> debug_kernel [<replaceable>filename</replaceable>] </screen>
+ </section>
+ <section remap="h3">
+ <title>Controlling Console Message Rate Limiting</title>
+ <para>Some console messages which are printed by Lustre are rate limited. When such messages are printed, they may be followed by a message saying "Skipped N previous similar message(s)," where N is the number of messages skipped. This rate limiting can be completely disabled by a libcfs module parameter called <literal>libcfs_console_ratelimit</literal>. To disable console message rate limiting, add this line to <literal>/etc/modprobe.d/lustre.conf</literal> and then reload Lustre modules.</para>
+ <screen>options libcfs libcfs_console_ratelimit=0</screen>
+ <para>It is also possible to set the minimum and maximum delays between rate-limited console messages using the module parameters <literal>libcfs_console_max_delay</literal> and <literal>libcfs_console_min_delay</literal>. Set these in <literal>/etc/modprobe.d/lustre.conf</literal> and then reload Lustre modules. Additional information on libcfs module parameters is available via <literal>modinfo</literal>:</para>
+ <screen>modinfo libcfs</screen>
</section>
</section>
<section xml:id="dbdoclet.50438274_80443">
- <title>28.3 Lustre Debugging for Developers</title>
- <para>The procedures in this section may be useful to developers debugging Lustre code.</para>
+ <title><indexterm><primary>debugging</primary><secondary>developers tools</secondary></indexterm>Lustre Debugging for Developers</title>
+ <para>The procedures in this section may be useful to developers debugging Lustre source
+ code.</para>
<section remap="h3">
- <title>28.3.1 Adding Debugging to the Lustre Source Code</title>
+ <title>Adding Debugging to the Lustre Source Code</title>
<para>The debugging infrastructure provides a number of macros that can be used in Lustre source code to aid in debugging or reporting serious errors.</para>
<para>To use these macros, you will need to set the <literal>DEBUG_SUBSYSTEM</literal> variable at the top of the file as shown below:</para>
<screen>#define DEBUG_SUBSYSTEM S_PORTALS</screen>
<row>
<entry>
<para> <emphasis role="bold">
- <literal>LBUG</literal>
+ <literal>LBUG()</literal>
</emphasis></para>
</entry>
<entry>
- <para>A panic-style assertion in the kernel which causes Lustre to dump its circular log to the <literal>/tmp/lustre-log</literal> file. This file can be retrieved after a reboot. LBUG freezes the thread to allow capture of the panic stack. A system reboot is needed to clear the thread.</para>
+ <para>A panic-style assertion in the kernel which causes the Lustre file system to
+ dump its circular log to the <literal>/tmp/lustre-log</literal> file. This file
+ can be retrieved after a reboot. <literal>LBUG()</literal> freezes the thread to
+ allow capture of the panic stack. A system reboot is needed to clear the
+ thread.</para>
</entry>
</row>
<row>
<entry>
<para> <emphasis role="bold">
- <literal>LASSERT</literal>
+ <literal>LASSERT()</literal>
</emphasis></para>
</entry>
<entry>
- <para>Validates a given expression as true, otherwise calls LBUG. The failed expression is printed on the console, although the values that make up the expression are not printed.</para>
+ <para>Validates a given expression as true, otherwise calls LBUG(). The failed expression is printed on the console, although the values that make up the expression are not printed.</para>
</entry>
</row>
<row>
<entry>
<para> <emphasis role="bold">
- <literal>LASSERTF</literal>
+ <literal>LASSERTF()</literal>
</emphasis></para>
</entry>
<entry>
- <para>Similar to LASSERT but allows a free-format message to be printed, like <literal>printf/printk</literal>.</para>
+ <para>Similar to <literal>LASSERT()</literal> but allows a free-format message to be printed, like <literal>printf/printk</literal>.</para>
</entry>
</row>
<row>
<entry>
<para> <emphasis role="bold">
- <literal>CDEBUG</literal>
+ <literal>CDEBUG()</literal>
</emphasis></para>
</entry>
<entry>
- <para>The basic, most commonly used debug macro that takes just one more argument than standard <literal>printf</literal> - the debug type. This message adds to the debug log with the debug mask set accordingly. Later, when a user retrieves the log for troubleshooting, they can filter based on this type.</para>
- <para><literal>CDEBUG(D_INFO, "This is my debug message: the number is %d\n", number)</literal>.</para>
+ <para>The basic, most commonly used debug macro that takes just one more argument than standard <literal>printf()</literal> - the debug type. This message adds to the debug log with the debug mask set accordingly. Later, when a user retrieves the log for troubleshooting, they can filter based on this type.</para>
+ <para><literal>CDEBUG(D_INFO, "debug message: rc=%d\n", number);</literal></para>
</entry>
</row>
<row>
<entry>
<para> <emphasis role="bold">
- <literal>CERROR</literal>
+ <literal>CDEBUG_LIMIT()</literal>
</emphasis></para>
</entry>
<entry>
- <para> Behaves similarly to <literal>CDEBUG</literal>, but unconditionally prints the message in the debug log and to the console. This is appropriate for serious errors or fatal conditions:</para>
- <para><literal>CERROR("Something very bad has happened, and the return code is %d.\n", rc);</literal></para>
+ <para> Behaves similarly to <literal>CDEBUG()</literal>, but rate limits this message when printing to the console (for <literal>D_WARN</literal>, <literal>D_ERROR</literal>, and <literal>D_CONSOLE</literal> message types. This is useful for messages that use a variable debug mask:</para>
+ <para><literal>CDEBUG(mask, "maybe bad: rc=%d\n", rc);</literal></para>
</entry>
</row>
<row>
<entry>
- <para> <emphasis role="bold"><literal>ENTRY</literal> and <literal>EXIT</literal></emphasis></para>
+ <para> <emphasis role="bold">
+ <literal>CERROR()</literal>
+ </emphasis></para>
</entry>
<entry>
- <para> Add messages to aid in call tracing (takes no arguments). When using these macros, cover all exit conditions to avoid confusion when the debug log reports that a function was entered, but never exited.</para>
+ <para>Internally using <literal>CDEBUG_LIMIT(D_ERROR, ...)</literal>, which unconditionally prints the message in the debug log and to the console. This is appropriate for serious errors or fatal conditions. Messages printed to the console are prefixed with <literal>LustreError:</literal>, and are rate-limited, to avoid flooding the console with duplicates.</para>
+ <para><literal>CERROR("Something bad happened: rc=%d\n", rc);</literal></para>
</entry>
</row>
<row>
<entry>
- <para> <emphasis role="bold"><literal>LDLM_DEBUG</literal> and <literal>LDLM_DEBUG_NOLOCK</literal></emphasis></para>
+ <para> <emphasis role="bold">
+ <literal>CWARN()</literal>
+ </emphasis></para>
</entry>
<entry>
- <para>Used when tracing MDS and VFS operations for locking. These macros build a thin trace that shows the protocol exchanges between nodes.</para>
+ <para> Behaves similarly to <literal>CERROR()</literal>, but prefixes the messages with <literal>Lustre:</literal>. This is appropriate for important, but not fatal conditions. Messages printed to the console are rate-limited.</para>
</entry>
</row>
<row>
<entry>
- <para> <literal>
- <replaceable role="bold">DEBUG_REQ</replaceable>
- </literal></para>
+ <para> <emphasis role="bold">
+ <literal>CNETERR()</literal>
+ </emphasis></para>
+ </entry>
+ <entry>
+ <para> Behaves similarly to <literal>CERROR()</literal>, but prints error messages for LNet if <literal>D_NETERR</literal> is set in the <literal>debug</literal> mask. This is appropriate for serious networking errors. Messages printed to the console are rate-limited.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para> <emphasis role="bold">
+ <literal>DEBUG_REQ()</literal>
+ </emphasis></para>
</entry>
<entry>
<para>Prints information about the given <literal>ptlrpc_request</literal> structure.</para>
+ <para><literal>DEBUG_REQ(D_RPCTRACE, req, ""Handled RPC: rc=%d\n", rc);</literal></para>
</entry>
</row>
<row>
<entry>
- <para> <literal>
- <replaceable role="bold">OBD_FAIL_CHECK</replaceable>
- </literal></para>
+ <para> <emphasis role="bold">
+ <literal>ENTRY</literal>
+ </emphasis></para>
</entry>
<entry>
- <para>Allows insertion of failure points into the Lustre code. This is useful to generate regression tests that can hit a very specific sequence of events. This works in conjunction with "<literal>sysctl -w lustre.fail_loc={fail_loc}</literal>" to set a specific failure point for which a given <literal>OBD_FAIL_CHECK</literal> will test.</para>
+ <para> Add messages to the entry of a function to aid in call tracing (takes no arguments). When using these macros, cover all exit conditions with a single <literal>EXIT</literal>, <literal>GOTO()</literal>, or <literal>RETURN()</literal> macro to avoid confusion when the debug log reports that a function was entered, but never exited.</para>
</entry>
</row>
<row>
<entry>
- <para> <literal>
- <replaceable role="bold">OBD_FAIL_TIMEOUT</replaceable>
- </literal></para>
+ <para> <emphasis role="bold">
+ <literal>EXIT</literal>
+ </emphasis></para>
</entry>
<entry>
- <para>Similar to <literal>OBD_FAIL_CHECK</literal>. Useful to simulate hung, blocked or busy processes or network devices. If the given <literal>fail_loc</literal> is hit, <literal>OBD_FAIL_TIMEOUT</literal> waits for the specified number of seconds.</para>
+ <para> Mark the exit of a function, to match <literal>ENTRY</literal> (takes no arguments).</para>
</entry>
</row>
<row>
<entry>
- <para> <literal>
- <replaceable role="bold">OBD_RACE</replaceable>
- </literal></para>
+ <para> <emphasis role="bold">
+ <literal>GOTO()</literal>
+ </emphasis></para>
</entry>
<entry>
- <para>Similar to <literal>OBD_FAIL_CHECK</literal>. Useful to have multiple processes execute the same code concurrently to provoke locking races. The first process to hit <literal>OBD_RACE</literal> sleeps until a second process hits <literal>OBD_RACE</literal>, then both processes continue.</para>
+ <para> Mark when code jumps via <literal>goto</literal> to the end of a function, to match <literal>ENTRY</literal>, and prints out the goto label and function return code in signed and unsigned decimal, and hexadecimal format.</para>
</entry>
</row>
<row>
<entry>
- <para> <literal>
- <replaceable role="bold">OBD_FAIL_ONCE</replaceable>
- </literal></para>
+ <para> <emphasis role="bold">
+ <literal>RETURN()</literal>
+ </emphasis></para>
</entry>
<entry>
- <para>A flag set on a <literal>lustre.fail_loc</literal> breakpoint to cause the <literal>OBD_FAIL_CHECK</literal> condition to be hit only one time. Otherwise, a <literal>fail_loc</literal> is permanent until it is cleared with "<literal>sysctl -w lustre.fail_loc=0</literal>".</para>
+ <para> Mark the exit of a function, to match <literal>ENTRY</literal>, and prints out the function return code in signed and unsigned decimal, and hexadecimal format.</para>
</entry>
</row>
<row>
<entry>
- <para><literal>
- <replaceable role="bold">OBD_FAIL_RAND</replaceable>
- </literal></para>
+ <para> <emphasis role="bold">
+ <literal>LDLM_DEBUG()</literal>
+ </emphasis></para>
+ <para> <emphasis role="bold">
+ <literal>LDLM_DEBUG_NOLOCK()</literal>
+ </emphasis></para>
</entry>
<entry>
- <para>Has <literal>OBD_FAIL_CHECK</literal> fail randomly; on average every (1 / lustre.fail_val) times.</para>
+ <para>Used when tracing LDLM locking operations. These macros build a thin trace that shows the locking requests on a node, and can also be linked across the client and server node using the printed lock handles.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para> <emphasis role="bold">
+ <literal>OBD_FAIL_CHECK()</literal>
+ </emphasis></para>
+ </entry>
+ <entry>
+ <para>Allows insertion of failure points into the Lustre source code. This is useful
+ to generate regression tests that can hit a very specific sequence of events. This
+ works in conjunction with "<literal>lctl set_param
+ fail_loc=<replaceable>fail_loc</replaceable></literal>" to set a specific
+ failure point for which a given <literal>OBD_FAIL_CHECK()</literal> will
+ test.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para> <emphasis role="bold">
+ <literal>OBD_FAIL_TIMEOUT()</literal>
+ </emphasis></para>
+ </entry>
+ <entry>
+ <para>Similar to <literal>OBD_FAIL_CHECK()</literal>. Useful to simulate hung, blocked or busy processes or network devices. If the given <literal>fail_loc</literal> is hit, <literal>OBD_FAIL_TIMEOUT()</literal> waits for the specified number of seconds.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para> <emphasis role="bold">
+ <literal>OBD_RACE()</literal>
+ </emphasis></para>
+ </entry>
+ <entry>
+ <para>Similar to <literal>OBD_FAIL_CHECK()</literal>. Useful to have multiple processes execute the same code concurrently to provoke locking races. The first process to hit <literal>OBD_RACE()</literal> sleeps until a second process hits <literal>OBD_RACE()</literal>, then both processes continue.</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para> <emphasis role="bold">
+ <literal>OBD_FAIL_ONCE</literal>
+ </emphasis></para>
+ </entry>
+ <entry>
+ <para>A flag set on a <literal>fail_loc</literal> breakpoint to cause the <literal>OBD_FAIL_CHECK()</literal> condition to be hit only one time. Otherwise, a <literal>fail_loc</literal> is permanent until it is cleared with "<literal>lctl set_param fail_loc=0</literal>".</para>
+ </entry>
+ </row>
+ <row>
+ <entry>
+ <para> <emphasis role="bold">
+ <literal>OBD_FAIL_RAND</literal>
+ </emphasis></para>
+ </entry>
+ <entry>
+ <para>A flag set on a <literal>fail_loc</literal> breakpoint to cause <literal>OBD_FAIL_CHECK()</literal> to fail randomly; on average every (1 / fail_val) times.</para>
</entry>
</row>
<row>
</emphasis></para>
</entry>
<entry>
- <para>Has <literal>OBD_FAIL_CHECK</literal> succeed <literal>lustre.fail_val</literal> times, and then fail permanently or once with <literal>OBD_FAIL_ONCE</literal>.</para>
+ <para>A flag set on a <literal>fail_loc</literal> breakpoint to cause <literal>OBD_FAIL_CHECK()</literal> to succeed <literal>fail_val</literal> times, and then fail permanently or once with <literal>OBD_FAIL_ONCE</literal>.</para>
</entry>
</row>
<row>
<entry>
- <para> <literal>
- <replaceable role="bold">OBD_FAIL_SOME</replaceable>
- </literal></para>
+ <para> <emphasis role="bold">
+ <literal>OBD_FAIL_SOME</literal>
+ </emphasis></para>
</entry>
<entry>
- <para>Has <literal>OBD_FAIL_CHECK</literal> fail <literal>lustre.fail_val</literal> times, and then succeed.</para>
+ <para>A flag set on <literal>fail_loc</literal> breakpoint to cause <literal>OBD_FAIL_CHECK</literal> to fail <literal>fail_val</literal> times, and then succeed.</para>
</entry>
</row>
</tbody>
</informaltable>
</section>
<section remap="h3">
- <title>28.3.2 Accessing a <literal>ptlrpc</literal> Request History</title>
+ <title>Accessing the <literal>ptlrpc</literal> Request History</title>
<para>Each service maintains a request history, which can be useful for first occurrence troubleshooting.</para>
- <para><literal>ptlrpc</literal> is an RPC protocol layered on LNET that deals with stateful servers and has semantics and built-in support for recovery.</para>
- <para>A <literal>prlrpc</literal> request history works as follows:</para>
+ <para><literal>ptlrpc</literal> is an RPC protocol layered on LNet that deals with stateful servers and has semantics and built-in support for recovery.</para>
+ <para>The ptlrpc request history works as follows:</para>
<orderedlist>
<listitem>
<para><literal>request_in_callback()</literal> adds the new request to the service's request history.</para>
<para>When a request buffer becomes idle, it is added to the service's request buffer history list.</para>
</listitem>
<listitem>
- <para>Buffers are culled from the service's request buffer history if it has grown above</para>
- <para><literal>req_buffer_history_max</literal> and its reqs are removed from the service's request history.</para>
+ <para>Buffers are culled from the service request buffer history if it has grown above <literal>req_buffer_history_max</literal> and its reqs are removed from the service request history.</para>
</listitem>
</orderedlist>
<para>Request history is accessed and controlled using the following /proc files under the service directory:</para>
<itemizedlist>
<listitem>
- <para>
- <literal>
- req_buffer_history_len
- </literal>
- </para>
+ <para><literal>req_buffer_history_len </literal></para>
<para>Number of request buffers currently in the history</para>
</listitem>
</itemizedlist>
<itemizedlist>
<listitem>
- <para>
- <literal>
- req_buffer_history_max
- </literal>
- </para>
+ <para><literal>req_buffer_history_max </literal></para>
<para>Maximum number of request buffers to keep</para>
</listitem>
</itemizedlist>
<itemizedlist>
<listitem>
- <para>
- <literal>
- req_history
- </literal>
- </para>
+ <para><literal>req_history </literal> </para>
<para>The request history</para>
</listitem>
</itemizedlist>
<para>Requests in the history include "live" requests that are currently being handled. Each line in <literal>req_history</literal> looks like:</para>
- <screen><seq>:<target NID>:<client ID>:<xid>:<length>:<phase> <svc specific> </screen>
+ <screen><replaceable>sequence</replaceable>:<replaceable>target_NID</replaceable>:<replaceable>client_NID</replaceable>:<replaceable>cliet_xid</replaceable>:<replaceable>request_length</replaceable>:<replaceable>rpc_phase</replaceable> <replaceable>service_specific_data</replaceable> </screen>
<informaltable frame="all">
<tgroup cols="2">
<colspec colname="c1" colwidth="50*"/>
<row>
<entry>
<para> <literal>
- <replaceable role="bold">target NID</replaceable>
+ <replaceable>target NID</replaceable>
</literal></para>
</entry>
<entry>
<row>
<entry>
<para> <literal>
- <replaceable role="bold">client ID</replaceable>
+ <replaceable>client ID</replaceable>
</literal></para>
</entry>
<entry>
<row>
<entry>
<para>
- <literal><replaceable>xid</replaceable></literal>
+ <literal>
+ <replaceable>xid</replaceable>
+ </literal>
</para>
</entry>
<entry>
</informaltable>
</section>
<section remap="h3">
- <title>28.3.3 Finding Memory Leaks Using <literal>leak_finder.pl</literal></title>
+ <title><indexterm><primary>debugging</primary><secondary>memory leaks</secondary></indexterm>Finding Memory Leaks Using <literal>leak_finder.pl</literal></title>
<para>Memory leaks can occur in code when memory has been allocated and then not freed once it is no longer required. The <literal>leak_finder.pl</literal> program provides a way to find memory leaks.</para>
<para>Before running this program, you must turn on debugging to collect all <literal>malloc</literal> and free entries. Run:</para>
- <screen>sysctl -w lnet.debug=+malloc </screen>
+ <screen>lctl set_param debug=+malloc </screen>
<para>Then complete the following steps:</para>
<orderedlist>
<listitem>
-
<para>Dump the log into a user-specified log file using lctl (see <xref linkend="dbdoclet.50438274_62472"/>).</para>
+ <para>Dump the log into a user-specified log file using lctl (see <xref linkend="dbdoclet.50438274_62472"/>).</para>
</listitem>
<listitem>
<para>Run the leak finder on the newly-created log dump:</para>
- <screen>perl leak_finder.pl <ascii-logname></screen>
+ <screen>perl leak_finder.pl <replaceable>ascii-logname</replaceable></screen>
</listitem>
</orderedlist>
<para>The output is:</para>
git://git.whamcloud.com / doc / manual.git / blobdiff