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<?xml version="1.0" encoding="ISO8859-1" standalone="no"?>
<!--
     The FreeBSD Documentation Project

     $FreeBSD$
-->

<chapter id="testing">
  <title>Regression and Performance Testing</title>

  <para>Regression tests are used to exercise a particular bit of the
    system to check that it works as expected, and to make sure that
    old bugs are not reintroduced.</para>

  <para>The &os; regression testing tools can be found in the &os;
    source tree in the directory <filename
      class="directory">src/tools/regression</filename>.</para>

  <section id="testing-micro-benchmark">
    <title>Micro Benchmark Checklist</title>

    <para>This section contains hints for doing proper
      micro-benchmarking on &os; or of &os; itself.</para>

    <para>It is not possible to use all of the suggestions below every
      single time, but the more used, the better the benchmark's
      ability to test small differences will be.</para>

    <itemizedlist>
      <listitem>
	<para>Disable <acronym>APM</acronym> and any other kind of
	  clock fiddling (<acronym>ACPI</acronym> ?).</para>
      </listitem>

      <listitem>
	<para>Run in single user mode.  E.g., &man.cron.8;, and other
	  daemons only add noise.  The &man.sshd.8; daemon can also
	  cause problems.  If ssh access is required during testing
	  either disable the SSHv1 key regeneration, or kill the
	  parent <command>sshd</command> daemon during the
	  tests.</para>
      </listitem>

      <listitem>
	<para>Do not run &man.ntpd.8;.</para>
      </listitem>

      <listitem>
	<para>If &man.syslog.3; events are generated, run
	  &man.syslogd.8; with an empty
	  <filename>/etc/syslogd.conf</filename>, otherwise, do not
	  run it.</para>
      </listitem>

      <listitem>
	<para>Minimize disk-I/O, avoid it entirely if possible.</para>
      </listitem>

      <listitem>
	<para>Do not mount file systems that are not needed.</para>
      </listitem>

      <listitem>
	<para>Mount <filename class="directory">/</filename>,
	  <filename class="directory">/usr</filename>, and any other
	  file system as read-only if possible.  This removes atime
	  updates to disk (etc.) from the I/O picture.</para>
      </listitem>

      <listitem>
	<para>Reinitialize the read/write test file system with
	  &man.newfs.8; and populate it from a &man.tar.1; or
	  &man.dump.8; file before every run.  Unmount and mount it
	  before starting the test.  This results in a consistent file
	  system layout.  For a worldstone test this would apply to
	  <filename class="directory">/usr/obj</filename> (just
	  reinitialize with <command>newfs</command> and mount).  To
	  get 100% reproducibility, populate the file system from a
	  &man.dd.1; file (i.e.: <command>dd
	    if=<filename>myimage</filename> of=<filename
	      class="devicefile">/dev/ad0s1h</filename>
	    bs=1m</command>)</para>
      </listitem>

      <listitem>
	<para>Use malloc backed or preloaded &man.md.4;
	  partitions.</para>
      </listitem>

      <listitem>
	<para>Reboot between individual iterations of the test, this
	  gives a more consistent state.</para>
      </listitem>

      <listitem>
	<para>Remove all non-essential device drivers from the kernel.
	  For instance if USB is not needed for the test, do not put
	  USB in the kernel.  Drivers which attach often have timeouts
	  ticking away.</para>
      </listitem>

      <listitem>
	<para>Unconfigure hardware that are not in use.  Detach disks
	  with &man.atacontrol.8; and &man.camcontrol.8; if the disks
	  are not used for the test.</para>
      </listitem>

      <listitem>
	<para>Do not configure the network unless it is being tested,
	  or wait until after the test has been performed to ship the
	  results off to another computer.</para>

	<para>If the system must be connected to a public network,
	  watch out for spikes of broadcast traffic.  Even though it
	  is hardly noticeable, it will take up CPU cycles.  Multicast
	  has similar caveats.</para>
      </listitem>

      <listitem>
	<para>Put each file system on its own disk.  This minimizes
	  jitter from head-seek optimizations.</para>
      </listitem>

      <listitem>
	<para>Minimize output to serial or VGA consoles.  Running
	  output into files gives less jitter.  (Serial consoles
	  easily become a bottleneck.)  Do not touch keyboard while
	  the test is running, even <keycap>space</keycap> or
	  <keycap>back-space</keycap> shows up in the numbers.</para>
      </listitem>

      <listitem>
	<para>Make sure the test is long enough, but not too long.  If
	  the test is too short, timestamping is a problem.  If it is
	  too long temperature changes and drift will affect the
	  frequency of the quartz crystals in the computer.  Rule of
	  thumb: more than a minute, less than an hour.</para>
      </listitem>

      <listitem>
	<para>Try to keep the temperature as stable as possible around
	  the machine.  This affects both quartz crystals and disk
	  drive algorithms.  To get real stable clock, consider
	  stabilized clock injection.  E.g., get a OCXO + PLL, inject
	  output into clock circuits instead of motherboard xtal.
	  Contact &a.phk; for more information about this.</para>
      </listitem>

      <listitem>
	<para>Run the test at least 3 times but it is better to run
	  more than 20 times both for <quote>before</quote> and
	  <quote>after</quote> code.  Try to interleave if possible
	  (i.e.: do not run 20 times before then 20 times after), this
	  makes it possible to spot environmental effects.  Do not
	  interleave 1:1, but 3:3, this makes it possible to spot
	  interaction effects.</para>

	<para>A good pattern is: <literal>bababa{bbbaaa}*</literal>.
	  This gives hint after the first 1+1 runs (so it is possible
	  to stop the test if it goes entirely the wrong way), a
	  standard deviation after the first 3+3 (gives a good
	  indication if it is going to be worth a long run) and
	  trending and interaction numbers later on.</para>
      </listitem>

      <listitem>
	<para>Use &man.ministat.1;
	  to see if the numbers are significant.  Consider buying
	  <quote>Cartoon guide to statistics</quote> ISBN:
	  0062731025, highly recommended, if you have forgotten or
	  never learned about standard deviation and Student's
	  T.</para>
      </listitem>

      <listitem>
	<para>Do not use background &man.fsck.8; unless the test is a
	  benchmark of background <command>fsck</command>.  Also,
	  disable <varname>background_fsck</varname> in
	  <filename>/etc/rc.conf</filename> unless the benchmark is
	  not started at least 60+<quote><command>fsck</command>
	    runtime</quote> seconds after the boot, as &man.rc.8;
	  wakes up and checks if <command>fsck</command> needs to run
	  on any file systems when background <command>fsck</command>
	  is enabled.  Likewise, make sure there are no snapshots
	  lying around unless the benchmark is a test with
	  snapshots.</para>
      </listitem>

      <listitem>
	<para>If the benchmark show unexpected bad performance, check
	  for things like high interrupt volume from an unexpected
	  source.  Some versions of <acronym>ACPI</acronym> have been
	  reported to <quote>misbehave</quote> and generate excess
	  interrupts.  To help diagnose odd test results, take a few
	  snapshots of <command>vmstat -i</command> and look for
	  anything unusual.</para>
      </listitem>

      <listitem>
	<para>Make sure to be careful about optimization parameters
	  for kernel and userspace, likewise debugging.  It is easy to
	  let something slip through and realize later the test was
	  not comparing the same thing.</para>
      </listitem>

      <listitem>
	<para>Do not ever benchmark with the
	  <literal>WITNESS</literal> and <literal>INVARIANTS</literal>
	  kernel options enabled unless the test is interested to
	  benchmarking those features.  <literal>WITNESS</literal> can
	  cause 400%+ drops in performance.  Likewise, userspace
	  &man.malloc.3; parameters default differently in -CURRENT
	  from the way they ship in production releases.</para>
      </listitem>
    </itemizedlist>
  </section>

  <section id="testing-tinderbox">
    <title>The &os; Source Tinderbox</title>

    <para>The source Tinderbox consists of:</para>

    <itemizedlist>
      <listitem>
	<para>A build script, <filename>tinderbox</filename>, that
	  automates checking out a specific version of the &os; source
	  tree and building it.</para>
      </listitem>
      <listitem>
	<para>A supervisor script, <filename>tbmaster</filename>, that
	  monitors individual Tinderbox instances, logs their output,
	  and emails failure notices.</para>
      </listitem>
      <listitem>
	<para>A <acronym>CGI</acronym> script named
	  <filename>index.cgi</filename> that reads a set of tbmaster
	  logs and presents an easy-to-read <acronym>HTML</acronym>
	  summary of them.</para>
      </listitem>
      <listitem>
	<para>A set of build servers that continually test the tip of
	  the most important &os; code branches.</para>
      </listitem>
      <listitem>
	<para>A webserver that keeps a complete set of Tinderbox logs
	  and displays an up-to-date summary.</para>
      </listitem>
    </itemizedlist>

    <para>The scripts are maintained and were developed by &a.des;,
      and are now written in Perl, a move on from their original
      incarnation as shell scripts.  All scripts and configuration
      files are kept in <ulink
	url="http://www.freebsd.org/cgi/cvsweb.cgi/projects/tinderbox/">/projects/tinderbox/</ulink>.</para>

    <para>For more information about the tinderbox and tbmaster
      scripts at this stage, see their respective man pages:
      tinderbox(1) and tbmaster(1).</para>

    <section>
      <title>The <filename>index.cgi</filename> Script</title>

      <para>The <filename>index.cgi</filename> script generates the
	<acronym>HTML</acronym> summary of tinderbox and tbmaster
	logs.  Although originally intended to be used as a
	<acronym>CGI</acronym> script, as indicated by its name, this
	script can also be run from the command line or from a
	&man.cron.8; job, in which case it will look for logs in the
	directory where the script is located.  It will automatically
	detect context, generating <acronym>HTTP</acronym> headers
	when it is run as a <acronym>CGI</acronym> script.  It
	conforms to <acronym>XHTML</acronym> standards and is styled
	using <acronym>CSS</acronym>.</para>

      <para>The script starts in the <function>main()</function> block
	by attempting to verify that it is running on the official
	Tinderbox website.  If it is not, a page indicating it is not
	an official website is produced, and a <acronym>URL</acronym>
	to the official site is provided.</para>

      <para>Next, it scans the log directory to get an inventory of
	configurations, branches and architectures for which log files
	exist, to avoid hard-coding a list into the script and
	potentially ending up with blank rows or columns.  This
	information is derived from the names of the log files
	matching the following pattern:</para>

      <programlisting>tinderbox-$config-$branch-$arch-$machine.{brief,full}</programlisting>

      <para>The configurations used on the official Tinderbox build
	servers are named for the branches they build.  For example,
	the <literal>releng_8</literal> configuration is used to build
	<literal>RELENG_8</literal> as well as all still-supported
	release branches.</para>

      <para>Once all of this startup procedure has been successfully
	completed, <function>do_config()</function> is called for each
	configuration.</para>

      <para>The <function>do_config()</function> function generates
	<acronym>HTML</acronym> for a single Tinderbox
	configuration.</para>

      <para>It works by first generating a header row, then iterating
	over each branch build with the specified configuration,
	producing a single row of results for each in the following
	manner:</para>

      <itemizedlist>
	<listitem>
	  <para>For each item:</para>
	  <itemizedlist>
	    <listitem>
	      <para>For each machine within that architecture:</para>
	      <itemizedlist>
		<listitem>
		  <para>If a brief log file exists, then:</para>
		  <itemizedlist>
		    <listitem>
		      <para>Call <function>success()</function> to
			detemine the outcome of the build.</para>
		    </listitem>
		    <listitem>
		      <para>Output the modification size.</para>
		    </listitem>
		    <listitem>
		      <para>Output the size of the brief log file with
			a link to the log file itself.</para>
		    </listitem>
		    <listitem>
		      <para>If a full log file also exists,
			then:</para>
		      <itemizedlist>
			<listitem>
			  <para>Output the size of the full log file
			    with a link to the log file itself.</para>
			</listitem>
		      </itemizedlist>
		    </listitem>
		  </itemizedlist>
		</listitem>
		<listitem>
		  <para>Otherwise:</para>
		  <itemizedlist>
		    <listitem>
		      <para>No output.</para>
		    </listitem>
		  </itemizedlist>
		</listitem>
	      </itemizedlist>
	    </listitem>
	  </itemizedlist>
	</listitem>
      </itemizedlist>

      <para>The <function>success()</function> function mentioned
	above scans a brief log file for the string <quote>tinderbox
	  run completed</quote> in order to determine whether the
	build was successful.</para>

      <para>Configurations and branches are sorted according to their
	branch rank.  This is computed as follows:</para>

      <itemizedlist>
	<listitem>
	  <para><literal>HEAD</literal> and <literal>CURRENT</literal>
	    have rank 9999.</para>
	</listitem>
	<listitem>
	  <para><literal>RELENG_<replaceable>x</replaceable></literal>
	    has rank <replaceable>xx</replaceable>99.</para>
	</listitem>
	<listitem>
	  <para><literal>RELENG_<replaceable>x</replaceable>_<replaceable>y</replaceable></literal>
	    has rank <replaceable>xxyy</replaceable>.</para>
	</listitem>
      </itemizedlist>

      <para>Tthis means that <literal>HEAD</literal> always ranks
	highest, and <literal>RELENG</literal> branches are ranked in
	numerical order, with each <literal>STABLE</literal> branch
	ranking higher than the release branches forked off of it.
	For instance, for &os;&nbsp;8, the order from highest to
	lowest would be:</para>

      <itemizedlist>
	<listitem>
	  <para><literal>RELENG_8</literal> (branch rank 899).</para>
	</listitem>
	<listitem>
	  <para><literal>RELENG_8_3</literal> (branch rank
	    803).</para>
	</listitem>
	<listitem>
	  <para><literal>RELENG_8_2</literal> (branch rank
	    802).</para>
	</listitem>
	<listitem>
	  <para><literal>RELENG_8_1</literal> (branch rank
	    801).</para>
	</listitem>
	<listitem>
	  <para><literal>RELENG_8_0</literal> (branch rank
	    800).</para>
	</listitem>
      </itemizedlist>

      <para>The colors that Tinderbox uses for each cell in the table
	are defined by <acronym>CSS</acronym>.  Successful builds are
	displayed with green text; unsuccessful builds are displayed
	with red text.  The color fades as time passes since the
	corresponding build, with every half an hour bringing the
	color closer to grey.</para>
    </section>

    <section>
      <title>Official Build Servers</title>

      <para>The official Tinderbox build servers are hosted by <ulink
	  url="http://www.sentex.ca">Sentex Data
	  Communications</ulink>, who also host the <ulink
	  url="http://www.freebsd.org/projects/netperf/cluster.html">&os;
	  Netperf Cluster</ulink>.</para>

      <para>Three build servers currently exist:</para>

      <para><emphasis>freebsd-current.sentex.ca</emphasis>
	builds:</para>

      <itemizedlist>
	<listitem>
	  <para><literal>HEAD</literal> for amd64, arm, i386,
	    i386/pc98, ia64, mips, powerpc, powerpc64, and sparc64,
	    which takes approximately four hours.</para>
	</listitem>
	<listitem>
	  <para><literal>RELENG_9</literal> and supported
	    9.<replaceable>X</replaceable> branches for amd64, arm,
	    i386, i386/pc98, ia64, mips, powerpc, powerpc64, and
	    sparc64, which takes approximately three and a half
	    hours.</para>
	</listitem>
      </itemizedlist>

      <para><emphasis>freebsd-stable.sentex.ca</emphasis>
	builds:</para>

      <itemizedlist>
	<listitem>
	  <para><literal>RELENG_8</literal> and supported
	    8.<replaceable>X</replaceable> branches for amd64, i386,
	    i386/pc98, ia64, mips, powerpc and sparc64, and each
	    branch takes approximately six hours.</para>
	</listitem>
      </itemizedlist>

      <para><emphasis>freebsd-legacy.sentex.ca</emphasis>
	builds:</para>

      <itemizedlist>
	<listitem>
	  <para><literal>RELENG_7</literal> and supported
	    7.<replaceable>X</replaceable> branches for amd64, i386,
	    i386/pc98, ia64, powerpc, and sparc64, and each branch
	    takes approximately three hours.</para>
	</listitem>
      </itemizedlist>
    </section>

    <section>
      <title>Official Summary Site</title>

      <para>Summaries and logs from the official build servers are
	available online at <ulink
	  url="http://tinderbox.FreeBSD.org">http://tinderbox.FreeBSD.org</ulink>,
	hosted by &a.des; and set up as follows:</para>

      <itemizedlist>
	<listitem>
	  <para>A &man.cron.8; job checks the build servers at regular
	    intervals and downloads any new log files using
	    &man.rsync.1;.</para>
	</listitem>
	<listitem>
	  <para>Apache is set up to use <filename>index.cgi</filename>
	    as <literal>DirectoryIndex</literal>.</para>
	</listitem>
	<listitem>
	  <para>A <ulink
	      url="https://www.varnish-cache.org/">Varnish</ulink>
	    instance in front of Apache ensures that
	    <filename>index.cgi</filename> does not need to run more
	    than once every two minutes.</para>
	</listitem>
      </itemizedlist>
    </section>
  </section>
</chapter>