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<chapter>
    <header>
        <copyright>
            <year>2016</year><year>2017</year>
            <holder>Ericsson AB. All Rights Reserved.</holder>
        </copyright>
        <legalnotice>
            Licensed under the Apache License, Version 2.0 (the "License");
            you may not use this file except in compliance with the License.
            You may obtain a copy of the License at

            http://www.apache.org/licenses/LICENSE-2.0

            Unless required by applicable law or agreed to in writing, software
            distributed under the License is distributed on an "AS IS" BASIS,
            WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
            See the License for the specific language governing permissions and
            limitations under the License.
        </legalnotice>

        <title>LTTng and Erlang/OTP</title>
        <prepared></prepared>
        <responsible></responsible>
        <docno></docno>
        <approved></approved>
        <checked></checked>
        <date>2016-04-27</date>
        <rev></rev>
        <file>LTTng.xml</file>
    </header>

    <section>
        <title>Introduction</title>
        <p>The Linux Trace Toolkit: next generation is an open source system software package
            for correlated tracing of the Linux kernel, user applications and libraries. </p>
        <p>For more information, please visit <url href="http://lttng.org">http://lttng.org</url></p>
    </section>

    <section>
        <title>Building Erlang/OTP with LTTng support</title>
        <p>
            Configure and build Erlang with LTTng support:
        </p>
        <p>For LTTng to work properly with Erlang/OTP you need
            the following packages installed:</p>

      <list type="bulleted">
          <item><p>LTTng-tools: a command line interface to control tracing sessions.</p></item>
          <item><p>LTTng-UST: user space tracing library.</p></item>
      </list>

      <p>On Ubuntu this can be installed via <c>aptitude</c>:</p>

      <code type="none">$ sudo aptitude install lttng-tools liblttng-ust-dev</code>
      <p>See <url href="http://lttng.org/docs/#doc-installing-lttng">Installing LTTng</url>
          for more information on how to install LTTng on your system.</p>

      <p>After LTTng is properly installed on the system Erlang/OTP can be built with LTTng support.</p>
 

<code type="none">$ ./configure --with-dynamic-trace=lttng
$ make </code>
    </section>

    <section>
        <title>Dyntrace Tracepoints</title>
        <p>All tracepoints are in the domain of <c>org_erlang_dyntrace</c></p>
        <p>All Erlang types are the string equivalent in LTTng.</p>

        <p><em>process_spawn</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>parent : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>entry : string</c> :: Code Location. Ex. <c>"lists:sort/1"</c></item>
        </list>
        <p>
            Available through
            <seealso marker="erts:erlang#trace-3"><c>erlang:trace/3</c></seealso> with trace flag <c>procs</c> and <c>{tracer,dyntrace,[]}</c> as tracer module.
        </p>
        <p>Example:</p>
        <code type="none">process_spawn: { cpu_id = 3 }, { pid = "&lt;0.131.0&gt;", parent = "&lt;0.130.0&gt;", entry = "erlang:apply/2" }</code>

        <p><em>process_link</em></p>
        <list type="bulleted">
            <item><c>to : string</c> :: Process ID or Port ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>from : string</c> :: Process ID or Port ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>type : string</c> :: <c>"link" | "unlink"</c></item>
        </list>
        <p>
            Available through
            <seealso marker="erts:erlang#trace-3"><c>erlang:trace/3</c></seealso> with trace flag <c>procs</c> and <c>{tracer,dyntrace,[]}</c> as tracer module.
        </p>
        <p>Example:</p>
        <code type="none">process_link: { cpu_id = 3 }, { from = "&lt;0.130.0&gt;", to = "&lt;0.131.0&gt;", type = "link" }</code>


        <p><em>process_exit</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>reason : string</c> :: Exit reason. Ex. <c>"normal"</c></item>
        </list>
        <p>
            Available through
            <seealso marker="erts:erlang#trace-3"><c>erlang:trace/3</c></seealso> with trace flag <c>procs</c> and <c>{tracer,dyntrace,[]}</c> as tracer module.
        </p>
        <p>Example:</p>
        <code type="none">process_exit: { cpu_id = 3 }, { pid = "&lt;0.130.0&gt;", reason = "normal" }</code>

        <p><em>process_register</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>name : string</c> :: Registered name. Ex. <c>"error_logger"</c></item>
            <item><c>type : string</c> :: <c>"register" | "unregister"</c></item>
        </list>
        <p>Example:</p>
        <code type="none">process_register: { cpu_id = 0 }, { pid = "&lt;0.128.0&gt;", name = "dyntrace_lttng_SUITE" type = "register" }</code>

        <p><em>process_scheduled</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>entry : string</c> :: Code Location. Ex. <c>"lists:sort/1"</c></item>
            <item><c>type : string</c> :: <c>"in" | "out" | "in_exiting" | "out_exiting" | "out_exited"</c></item>
        </list>
        <p>
            Available through
            <seealso marker="erts:erlang#trace-3"><c>erlang:trace/3</c></seealso> with trace flag <c>running</c> and <c>{tracer,dyntrace,[]}</c> as tracer module.
        </p>
        <p>Example:</p>
        <code type="none">process_scheduled: { cpu_id = 0 }, { pid = "&lt;0.136.0&gt;", entry = "erlang:apply/2", type = "in" }</code>


        <p><em>port_open</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>driver : string</c> :: Driver name. Ex. <c>"efile"</c></item>
            <item><c>port : string</c> :: Port ID. Ex. <c>"#Port&lt;0.1031&gt;"</c></item>
        </list>
        <p>
            Available through
            <seealso marker="erts:erlang#trace-3"><c>erlang:trace/3</c></seealso> with trace flag <c>ports</c> and <c>{tracer,dyntrace,[]}</c> as tracer module.
        </p>
        <p>Example:</p>
        <code type="none">port_open: { cpu_id = 5 }, { pid = "&lt;0.131.0&gt;", driver = "'/bin/sh -s unix:cmd'", port = "#Port&lt;0.1887&gt;" }</code>

        <p><em>port_exit</em></p>
        <list type="bulleted">
            <item><c>port : string</c> :: Port ID. Ex. <c>"#Port&lt;0.1031&gt;"</c></item>
            <item><c>reason : string</c> :: Exit reason. Ex. <c>"normal"</c></item>
        </list>
        <p>
            Available through
            <seealso marker="erts:erlang#trace-3"><c>erlang:trace/3</c></seealso> with trace flag <c>ports</c> and <c>{tracer,dyntrace,[]}</c> as tracer module.
        </p>
        <p>Example:</p>
        <code type="none">port_exit: { cpu_id = 5 }, { port = "#Port&lt;0.1887&gt;", reason = "normal" }</code>

        <p><em>port_link</em></p>
        <list type="bulleted">
            <item><c>to : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>from : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>type : string</c> :: <c>"link" | "unlink"</c></item>
        </list>
        <p>
            Available through
            <seealso marker="erts:erlang#trace-3"><c>erlang:trace/3</c></seealso> with trace flag <c>ports</c> and <c>{tracer,dyntrace,[]}</c> as tracer module.
        </p>
        <p>Example:</p>
        <code type="none">port_link: { cpu_id = 5 }, { from = "#Port&lt;0.1887&gt;", to = "&lt;0.131.0&gt;", type = "unlink" }</code>

        <p><em>port_scheduled</em></p>
        <p>
            Available through
            <seealso marker="erts:erlang#trace-3"><c>erlang:trace/3</c></seealso> with trace flag <c>running</c> and <c>{tracer,dyntrace,[]}</c> as tracer module.
        </p>
        <list type="bulleted">
            <item><c>port : string</c> :: Port ID. Ex. <c>"#Port&lt;0.1031&gt;"</c></item>
            <item><c>entry : string</c> :: Callback. Ex. <c>"open"</c></item>
            <item><c>type : string</c> :: <c>"in" | "out" | "in_exiting" | "out_exiting" | "out_exited"</c></item>
        </list>

        <p>Example:</p>
        <code type="none">port_scheduled: { cpu_id = 5 }, { pid = "#Port&lt;0.1905&gt;", entry = "close", type = "out" }</code>
        <p>
            Available through
            <seealso marker="erts:erlang#trace-3"><c>erlang:trace/3</c></seealso> with trace flag <c>running</c> and <c>{tracer,dyntrace,[]}</c> as tracer module.
        </p>
        <p><em>function_call</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>entry : string</c> :: Code Location. Ex. <c>"lists:sort/1"</c></item>
            <item><c>depth : integer</c> :: Stack depth. Ex. <c>0</c></item>
        </list>
        <p>
            Available through
            <seealso marker="erts:erlang#trace-3"><c>erlang:trace/3</c></seealso> with trace flag <c>call</c> and <c>{tracer,dyntrace,[]}</c> as tracer module.
        </p>
        <p>Example:</p>
        <code type="none">function_call: { cpu_id = 5 }, { pid = "&lt;0.145.0&gt;", entry = "dyntrace_lttng_SUITE:'-t_call/1-fun-1-'/0", depth = 0 }</code>

        <p><em>function_return</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>entry : string</c> :: Code Location. Ex. <c>"lists:sort/1"</c></item>
            <item><c>depth : integer</c> :: Stack depth. Ex. <c>0</c></item>
        </list>
        <p>
            Available through
            <seealso marker="erts:erlang#trace-3"><c>erlang:trace/3</c></seealso> with trace flag <c>call</c> or <c>return_to</c> and <c>{tracer,dyntrace,[]}</c> as tracer module.
        </p>
        <p>Example:</p>
        <code type="none">function_return: { cpu_id = 5 }, { pid = "&lt;0.145.0&gt;", entry = "dyntrace_lttng_SUITE:waiter/0", depth = 0 }</code>

        <p><em>function_exception</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>entry : string</c> :: Code Location. Ex. <c>"lists:sort/1"</c></item>
            <item><c>class : string</c> :: Error reason. Ex. <c>"error"</c></item>
        </list>
        <p>
            Available through
            <seealso marker="erts:erlang#trace-3"><c>erlang:trace/3</c></seealso> with trace flag <c>call</c> and <c>{tracer,dyntrace,[]}</c> as tracer module.
        </p>
        <p>Example:</p>
        <code type="none">function_exception: { cpu_id = 5 }, { pid = "&lt;0.144.0&gt;", entry = "t:call_exc/1", class = "error" }</code>

        <p><em>message_send</em></p>
        <list type="bulleted">
            <item><c>from : string</c> :: Process ID or Port ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>to : string</c> :: Process ID or Port ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>message : string</c> :: Message sent. Ex. <c>"{&lt;0.162.0&gt;,ok}"</c></item>
        </list>
        <p>
            Available through
            <seealso marker="erts:erlang#trace-3"><c>erlang:trace/3</c></seealso> with trace flag <c>send</c> and <c>{tracer,dyntrace,[]}</c> as tracer module.
        </p>
        <p>Example:</p>
        <code type="none">message_send: { cpu_id = 3 }, { from = "#Port&lt;0.1938&gt;", to = "&lt;0.160.0&gt;", message = "{#Port&lt;0.1938&gt;,eof}" }</code>

        <p><em>message_receive</em></p>
        <list type="bulleted">
            <item><c>to : string</c> :: Process ID or Port ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>message : string</c> :: Message received. Ex. <c>"{&lt;0.162.0&gt;,ok}"</c></item>
        </list>
        <p>
            Available through
            <seealso marker="erts:erlang#trace-3"><c>erlang:trace/3</c></seealso> with trace flag <c>'receive'</c> and <c>{tracer,dyntrace,[]}</c> as tracer module.
        </p>
        <p>Example:</p>
        <code type="none">message_receive: { cpu_id = 7 }, { to = "&lt;0.167.0&gt;", message = "{&lt;0.165.0&gt;,ok}" }</code>

        <p><em>gc_minor_start</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>need : integer</c> :: Heap need. Ex. <c>2</c></item>
            <item><c>heap : integer</c> :: Young heap word size. Ex. <c>233</c></item>
            <item><c>old_heap : integer</c> :: Old heap word size. Ex. <c>233</c></item>
        </list>
        <p>
            Available through
            <seealso marker="erts:erlang#trace-3"><c>erlang:trace/3</c></seealso> with trace flag <c>garbage_collection</c> and <c>{tracer,dyntrace,[]}</c> as tracer module.
        </p>
        <p>Example:</p>
        <code type="none">gc_minor_start: { cpu_id = 0 }, { pid = "&lt;0.172.0&gt;", need = 0, heap = 610, old_heap = 0 }</code>

        <p><em>gc_minor_end</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>reclaimed : integer</c> :: Heap reclaimed. Ex. <c>2</c></item>
            <item><c>heap : integer</c> :: Young heap word size. Ex. <c>233</c></item>
            <item><c>old_heap : integer</c> :: Old heap word size. Ex. <c>233</c></item>
        </list>
        <p>
            Available through
            <seealso marker="erts:erlang#trace-3"><c>erlang:trace/3</c></seealso> with trace flag <c>garbage_collection</c> and <c>{tracer,dyntrace,[]}</c> as tracer module.
        </p>
        <p>Example:</p>
        <code type="none">gc_minor_end: { cpu_id = 0 }, { pid = "&lt;0.172.0&gt;", reclaimed = 120, heap = 1598, old_heap = 1598 }</code>

        <p><em>gc_major_start</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>need : integer</c> :: Heap need. Ex. <c>2</c></item>
            <item><c>heap : integer</c> :: Young heap word size. Ex. <c>233</c></item>
            <item><c>old_heap : integer</c> :: Old heap word size. Ex. <c>233</c></item>
        </list>
        <p>
            Available through
            <seealso marker="erts:erlang#trace-3"><c>erlang:trace/3</c></seealso> with trace flag <c>garbage_collection</c> and <c>{tracer,dyntrace,[]}</c> as tracer module.
        </p>
        <p>Example:</p>
        <code type="none">gc_major_start: { cpu_id = 0 }, { pid = "&lt;0.172.0&gt;", need = 8, heap = 2586, old_heap = 1598 }</code>

        <p><em>gc_major_end</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>reclaimed : integer</c> :: Heap reclaimed. Ex. <c>2</c></item>
            <item><c>heap : integer</c> :: Young heap word size. Ex. <c>233</c></item>
            <item><c>old_heap : integer</c> :: Old heap word size. Ex. <c>233</c></item>
        </list>
        <p>
            Available through
            <seealso marker="erts:erlang#trace-3"><c>erlang:trace/3</c></seealso> with trace flag <c>garbage_collection</c> and <c>{tracer,dyntrace,[]}</c> as tracer module.
        </p>
        <p>Example:</p>
        <code type="none">gc_major_end: { cpu_id = 0 }, { pid = "&lt;0.172.0&gt;", reclaimed = 240, heap = 4185, old_heap = 0 }</code>

    </section>

    <section>
        <title>BEAM Tracepoints</title>
        <p>All tracepoints are in the domain of <c>org_erlang_otp</c></p>
        <p>All Erlang types are the string equivalent in LTTng.</p>

        <p><em>scheduler_poll</em></p>
        <list type="bulleted">
            <item><c>scheduler : integer</c> :: Scheduler ID. Ex. <c>1</c></item>
            <item><c>runnable : integer</c> :: Runnable. Ex. <c>1</c></item>
        </list>
        <p>Example:</p>
        <code type="none">scheduler_poll: { cpu_id = 4 }, { scheduler = 1, runnable = 1 }</code>

        <p><em>driver_init</em></p>
        <list type="bulleted">
            <item><c>driver : string</c> :: Driver name. Ex. <c>"efile"</c></item>
            <item><c>major : integer</c> :: Major version. Ex. <c>3</c></item>
            <item><c>minor : integer</c> :: Minor version. Ex. <c>1</c></item>
            <item><c>flags : integer</c> :: Flags. Ex. <c>1</c></item>
        </list>
        <p>Example:</p>
        <code type="none">driver_init: { cpu_id = 2 }, { driver = "caller_drv", major = 3, minor = 3, flags = 1 }</code>

        <p><em>driver_start</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>driver : string</c> :: Driver name. Ex. <c>"efile"</c></item>
            <item><c>port : string</c> :: Port ID. Ex. <c>"#Port&lt;0.1031&gt;"</c></item>
        </list>
        <p>Example:</p>
        <code type="none">driver_start: { cpu_id = 2 }, { pid = "&lt;0.198.0&gt;", driver = "caller_drv", port = "#Port&lt;0.3676&gt;" }</code>

        <p><em>driver_output</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>port : string</c> :: Port ID. Ex. <c>"#Port&lt;0.1031&gt;"</c></item>
            <item><c>driver : string</c> :: Driver name. Ex. <c>"efile"</c></item>
            <item><c>bytes : integer</c> :: Size of data returned. Ex. <c>82</c></item>
        </list>
        <p>Example:</p>
        <code type="none">driver_output: { cpu_id = 2 }, { pid = "&lt;0.198.0&gt;", port = "#Port&lt;0.3677&gt;", driver = "/bin/sh -s unix:cmd", bytes = 36 }</code>

        <p><em>driver_outputv</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>port : string</c> :: Port ID. Ex. <c>"#Port&lt;0.1031&gt;"</c></item>
            <item><c>driver : string</c> :: Driver name. Ex. <c>"efile"</c></item>
            <item><c>bytes : integer</c> :: Size of data returned. Ex. <c>82</c></item>
        </list>
        <p>Example:</p>
        <code type="none">driver_outputv: { cpu_id = 5 }, { pid = "&lt;0.194.0&gt;", port = "#Port&lt;0.3663&gt;", driver = "tcp_inet", bytes = 3 }</code>

        <p><em>driver_ready_input</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>port : string</c> :: Port ID. Ex. <c>"#Port&lt;0.1031&gt;"</c></item>
            <item><c>driver : string</c> :: Driver name. Ex. <c>"efile"</c></item>
        </list>
        <p>Example:</p>
        <code type="none">driver_ready_input: { cpu_id = 5 }, { pid = "&lt;0.189.0&gt;", port = "#Port&lt;0.3637&gt;", driver = "inet_gethost 4 " }</code>

        <p><em>driver_ready_output</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>port : string</c> :: Port ID. Ex. <c>"#Port&lt;0.1031&gt;"</c></item>
            <item><c>driver : string</c> :: Driver name. Ex. <c>"efile"</c></item>
        </list>
        <p>Example:</p>
        <code type="none">driver_ready_output: { cpu_id = 5 }, { pid = "&lt;0.194.0&gt;", port = "#Port&lt;0.3663&gt;", driver = "tcp_inet" }</code>

        <p><em>driver_timeout</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>port : string</c> :: Port ID. Ex. <c>"#Port&lt;0.1031&gt;"</c></item>
            <item><c>driver : string</c> :: Driver name. Ex. <c>"efile"</c></item>
        </list>
        <p>Example:</p>
        <code type="none">driver_timeout: { cpu_id = 5 }, { pid = "&lt;0.196.0&gt;", port = "#Port&lt;0.3664&gt;", driver = "tcp_inet" }</code>

        <p><em>driver_stop_select</em></p>
        <list type="bulleted">
            <item><c>driver : string</c> :: Driver name. Ex. <c>"efile"</c></item>
        </list>
        <p>Example:</p>
        <code type="none">driver_stop_select: { cpu_id = 5 }, { driver = "unknown" }</code>

        <p><em>driver_flush</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>port : string</c> :: Port ID. Ex. <c>"#Port&lt;0.1031&gt;"</c></item>
            <item><c>driver : string</c> :: Driver name. Ex. <c>"efile"</c></item>
        </list>
        <p>Example:</p>
        <code type="none">driver_flush: { cpu_id = 7 }, { pid = "&lt;0.204.0&gt;", port = "#Port&lt;0.3686&gt;", driver = "tcp_inet" }</code>

        <p><em>driver_stop</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>port : string</c> :: Port ID. Ex. <c>"#Port&lt;0.1031&gt;"</c></item>
            <item><c>driver : string</c> :: Driver name. Ex. <c>"efile"</c></item>
        </list>
        <p>Example:</p>
        <code type="none">driver_stop: { cpu_id = 5 }, { pid = "[]", port = "#Port&lt;0.3673&gt;", driver = "efile" }</code>

        <p><em>driver_process_exit</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>port : string</c> :: Port ID. Ex. <c>"#Port&lt;0.1031&gt;"</c></item>
            <item><c>driver : string</c> :: Driver name. Ex. <c>"efile"</c></item>
        </list>

        <p><em>driver_ready_async</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>port : string</c> :: Port ID. Ex. <c>"#Port&lt;0.1031&gt;"</c></item>
            <item><c>driver : string</c> :: Driver name. Ex. <c>"efile"</c></item>
        </list>
        <p>Example:</p>
        <code type="none">driver_ready_async: { cpu_id = 3 }, { pid = "&lt;0.181.0&gt;", port = "#Port&lt;0.3622&gt;", driver = "efile" }</code>

        <p><em>driver_call</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>port : string</c> :: Port ID. Ex. <c>"#Port&lt;0.1031&gt;"</c></item>
            <item><c>driver : string</c> :: Driver name. Ex. <c>"efile"</c></item>
            <item><c>command : integer</c> :: Command integer. Ex. <c>1</c></item>
            <item><c>bytes : integer</c> :: Size of data returned. Ex. <c>82</c></item>
        </list>
        <p>Example:</p>
        <code type="none">driver_call: { cpu_id = 2 }, { pid = "&lt;0.202.0&gt;", port = "#Port&lt;0.3676&gt;", driver = "caller_drv", command = 0, bytes = 2 }</code>

        <p><em>driver_control</em></p>
        <list type="bulleted">
            <item><c>pid : string</c> :: Process ID. Ex. <c>"&lt;0.131.0&gt;"</c></item>
            <item><c>port : string</c> :: Port ID. Ex. <c>"#Port&lt;0.1031&gt;"</c></item>
            <item><c>driver : string</c> :: Driver name. Ex. <c>"efile"</c></item>
            <item><c>command : integer</c> :: Command integer. Ex. <c>1</c></item>
            <item><c>bytes : integer</c> :: Size of data returned. Ex. <c>82</c></item>
        </list>
        <p>Example:</p>
        <code type="none">driver_control: { cpu_id = 3 }, { pid = "&lt;0.32767.8191&gt;", port = "#Port&lt;0.0&gt;", driver = "forker", command = 83, bytes = 32 }</code>

        <p><em>aio_pool_get</em></p>
        <list type="bulleted">
            <item><c>port : string</c> :: Port ID. Ex. <c>"#Port&lt;0.1031&gt;"</c></item>
            <item><c>length : integer</c> :: Async queue length. Ex. <c>0</c></item>
        </list>
        <p>Example:</p>
        <code type="none">aio_pool_get: { cpu_id = 4 }, { port = "#Port&lt;0.3614&gt;", length = 0 }</code>

        <p><em>aio_pool_put</em></p>
        <list type="bulleted">
            <item><c>port : string</c> :: Port ID. Ex. <c>"#Port&lt;0.1031&gt;"</c></item>
            <item><c>length : integer</c> :: Async queue length. Ex. <c>-1</c></item>
        </list>
        <p>Async queue length is not defined for <c>put</c> operations.</p>
        <p>Example:</p>
        <code type="none">aio_pool_put: { cpu_id = 3 }, { port = "#Port&lt;0.3614&gt;", length = -1 }</code>

        <p><em>carrier_create</em></p>
        <list type="bulleted">
            <item><c>type : string</c> :: Carrier type. Ex. <c>"ets_alloc"</c></item>
            <item><c>instance : integer</c> :: Allocator instance. Ex. <c>1</c></item>
            <item><c>size : integer</c> :: Carrier size. Ex. <c>262144</c></item>
            <item><c>mbc_carriers : integer</c> :: Number of multiblock carriers in instance. Ex. <c>3</c></item>
            <item><c>mbc_carriers_size : integer</c> :: Total size of multiblock blocks carriers in instance. Ex. <c>1343488</c></item>
            <item><c>mbc_blocks : integer</c> :: Number of multiblock blocks in instance. Ex. <c>122</c></item>
            <item><c>mbc_blocks_size : integer</c> :: Total size of all multiblock blocks in instance. Ex. <c>285296</c></item>
            <item><c>sbc_carriers : integer</c> :: Number of singleblock carriers in instance. Ex. <c>1</c></item>
            <item><c>sbc_carriers_size : integer</c> :: Total size of singleblock blocks carriers in instance. Ex. <c>1343488</c></item>
            <item><c>sbc_blocks : integer</c> :: Number of singleblocks in instance. Ex. <c>1</c></item>
            <item><c>sbc_blocks_size : integer</c> :: Total size of all singleblock blocks in instance. Ex. <c>285296</c></item>

        </list>
        <p>Example:</p>
        <code type="none">carrier_create: { cpu_id = 2 }, { type = "ets_alloc", instance = 7, size = 2097152, mbc_carriers = 4, mbc_carriers_size = 3440640, mbc_blocks = 526, mbc_blocks_size = 1278576, sbc_carriers = 0, sbc_carriers_size = 0, sbc_blocks = 0, sbc_blocks_size = 0 }</code>

        <p><em>carrier_destroy</em></p>
        <list type="bulleted">
            <item><c>type : string</c> :: Carrier type. Ex. <c>"ets_alloc"</c></item>
            <item><c>instance : integer</c> :: Allocator instance. Ex. <c>1</c></item>
            <item><c>size : integer</c> :: Carrier size. Ex. <c>262144</c></item>
            <item><c>mbc_carriers : integer</c> :: Number of multiblock carriers in instance. Ex. <c>3</c></item>
            <item><c>mbc_carriers_size : integer</c> :: Total size of multiblock blocks carriers in instance. Ex. <c>1343488</c></item>
            <item><c>mbc_blocks : integer</c> :: Number of multiblock blocks in instance. Ex. <c>122</c></item>
            <item><c>mbc_blocks_size : integer</c> :: Total size of all multiblock blocks in instance. Ex. <c>285296</c></item>
            <item><c>sbc_carriers : integer</c> :: Number of singleblock carriers in instance. Ex. <c>1</c></item>
            <item><c>sbc_carriers_size : integer</c> :: Total size of singleblock blocks carriers in instance. Ex. <c>1343488</c></item>
            <item><c>sbc_blocks : integer</c> :: Number of singleblocks in instance. Ex. <c>1</c></item>
            <item><c>sbc_blocks_size : integer</c> :: Total size of all singleblock blocks in instance. Ex. <c>285296</c></item>

        </list>
        <p>Example:</p>
        <code type="none">carrier_destroy: { cpu_id = 6 }, { type = "ets_alloc", instance = 7, size = 262144, mbc_carriers = 3, mbc_carriers_size = 3178496, mbc_blocks = 925, mbc_blocks_size = 2305336, sbc_carriers = 0, sbc_carriers_size = 0, sbc_blocks = 0, sbc_blocks_size = 0 }</code>

        <p><em>carrier_pool_put</em></p>
        <list type="bulleted">
            <item><c>type : string</c> :: Carrier type. Ex. <c>"ets_alloc"</c></item>
            <item><c>instance : integer</c> :: Allocator instance. Ex. <c>1</c></item>
            <item><c>size : integer</c> :: Carrier size. Ex. <c>262144</c></item>
        </list>
        <p>Example:</p>
        <code type="none">carrier_pool_put: { cpu_id = 3 }, { type = "ets_alloc", instance = 5, size = 1048576 }</code>

        <p><em>carrier_pool_get</em></p>
        <list type="bulleted">
            <item><c>type : string</c> :: Carrier type. Ex. <c>"ets_alloc"</c></item>
            <item><c>instance : integer</c> :: Allocator instance. Ex. <c>1</c></item>
            <item><c>size : integer</c> :: Carrier size. Ex. <c>262144</c></item>
        </list>
        <p>Example:</p>
        <code type="none">carrier_pool_get: { cpu_id = 7 }, { type = "ets_alloc", instance = 4, size = 3208 }</code>
    </section>

    <section>
        <title>Example of process tracing</title>
    <p>An example of process tracing of <c>os_mon</c> and friends.</p>

    <p>Clean start of lttng in a bash shell.</p>

    <pre>$ lttng create erlang-demo
Spawning a session daemon
Session erlang-demo created.
Traces will be written in /home/egil/lttng-traces/erlang-demo-20160526-165920</pre>

     <p>Start an Erlang node with lttng enabled.</p>

     <pre>$ erl
Erlang/OTP 19 [erts-8.0] [source-4d7b24d] [64-bit] [smp:8:8] [async-threads:10] [hipe] [kernel-poll:false] [lttng]

Eshell V8.0  (abort with ^G)
1></pre>

     <p>Load the <c>dyntrace</c> module.</p>

     <pre>1> <input>l(dyntrace).</input>
{module,dyntrace}</pre>

     <p>All tracepoints via dyntrace are now visibile and can be listed through <c>lttng list -u</c>.</p>

     <p>Enable the process_register LTTng tracepoint for Erlang.</p>

     <pre>$ lttng enable-event -u org_erlang_dyntrace:process_register
UST event org_erlang_dyntrace:process_register created in channel channel0</pre>

     <p>Enable process tracing for new processes and use <c>dyntrace</c> as tracer backend.</p>

     <pre>2> <input>erlang:trace(new,true,[procs,{tracer,dyntrace,[]}]).</input>
0</pre>

     <p>Start LTTng tracing.</p>

     <pre>$ lttng start
Tracing started for session erlang-demo</pre>

     <p>Start the <c>os_mon</c> application in Erlang.</p>

     <pre>3> <input>application:ensure_all_started(os_mon).</input>
{ok,[sasl,os_mon]}</pre>

     <p>Stop LTTng tracing and view the result.</p>

     <pre>$ lttng stop
Tracing stopped for session erlang-demo
$ lttng view
[17:20:42.561168759] (+?.?????????) elxd1168lx9 org_erlang_dyntrace:process_register: \
    { cpu_id = 5 }, { pid = "&lt;0.66.0&gt;", name = "sasl_sup", type = "register" }
[17:20:42.561215519] (+0.000046760) elxd1168lx9 org_erlang_dyntrace:process_register: \
    { cpu_id = 5 }, { pid = "&lt;0.67.0&gt;", name = "sasl_safe_sup", type = "register" }
[17:20:42.562149024] (+0.000933505) elxd1168lx9 org_erlang_dyntrace:process_register: \
    { cpu_id = 5 }, { pid = "&lt;0.68.0&gt;", name = "alarm_handler", type = "register" }
[17:20:42.571035803] (+0.008886779) elxd1168lx9 org_erlang_dyntrace:process_register: \
    { cpu_id = 5 }, { pid = "&lt;0.69.0&gt;", name = "release_handler", type = "register" }
[17:20:42.574939868] (+0.003904065) elxd1168lx9 org_erlang_dyntrace:process_register: \
    { cpu_id = 5 }, { pid = "&lt;0.74.0&gt;", name = "os_mon_sup", type = "register" }
[17:20:42.576818712] (+0.001878844) elxd1168lx9 org_erlang_dyntrace:process_register: \
    { cpu_id = 5 }, { pid = "&lt;0.75.0&gt;", name = "disksup", type = "register" }
[17:20:42.580032013] (+0.003213301) elxd1168lx9 org_erlang_dyntrace:process_register: \
    { cpu_id = 5 }, { pid = "&lt;0.76.0&gt;", name = "memsup", type = "register" }
[17:20:42.583046339] (+0.003014326) elxd1168lx9 org_erlang_dyntrace:process_register: \
    { cpu_id = 5 }, { pid = "&lt;0.78.0&gt;", name = "cpu_sup", type = "register" }
[17:20:42.586206242] (+0.003159903) elxd1168lx9 org_erlang_dyntrace:process_register: \
    { cpu_id = 5 }, { pid = "&lt;0.82.0&gt;", name = "timer_server", type = "register" }</pre>
    </section>
</chapter>
