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diff --git a/lib/megaco/doc/src/megaco_performance.xml b/lib/megaco/doc/src/megaco_performance.xml new file mode 100644 index 0000000000..b34ee4f389 --- /dev/null +++ b/lib/megaco/doc/src/megaco_performance.xml @@ -0,0 +1,328 @@ +<?xml version="1.0" encoding="latin1" ?> +<!DOCTYPE chapter SYSTEM "chapter.dtd"> + +<chapter> + <header> + <copyright> + <year>2002</year><year>2009</year> + <holder>Ericsson AB. All Rights Reserved.</holder> + </copyright> + <legalnotice> + The contents of this file are subject to the Erlang Public License, + Version 1.1, (the "License"); you may not use this file except in + compliance with the License. You should have received a copy of the + Erlang Public License along with this software. If not, it can be + retrieved online at http://www.erlang.org/. + + Software distributed under the License is distributed on an "AS IS" + basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See + the License for the specific language governing rights and limitations + under the License. + + </legalnotice> + + <title>Performance comparison</title> + <prepared>Håkan Mattsson</prepared> + <responsible>Håkan Mattsson</responsible> + <docno></docno> + <approved>Håkan Mattsson</approved> + <checked></checked> + <date>2007-06-15</date> + <rev>%VSN%</rev> + <file>megaco_performance.xml</file> + </header> + + <section> + <title>Comparison of encoder/decoders</title> + <p>The Megaco/H.248 standard defines both a plain text encoding and a + binary encoding (ASN.1 BER) and we have implemented encoders and + decoders for both. We do supply a bunch of different encoding/decoding + modules and the user may in fact implement their own (like our erl_dist + module). Using a non-standard encoding format has its obvious drawbacks, + but may be useful in some configurations.</p> + + <p>We have made four different measurements of our Erlang/OTP + implementation of the Megaco/H.248 protocol stack, in order to compare + our different encoders/decoders. The result of each one is summarized + in the table below.</p> + + <p>The result above are the fastest + of these configurations for each codec. The figures presented are + the average of all used messages.</p> + + <p>For comparison, also included are performance figures + where the flex driver was built as <c>non-reentrant</c> flex + (figures within parenthesis). </p> + + <table> + <row> + <cell align="left" valign="middle"><em>Codec and config</em></cell> + <cell align="center" valign="middle"><em>Size</em></cell> + <cell align="center" valign="middle"><em>Encode</em></cell> + <cell align="center" valign="middle"><em>Decode</em></cell> + <cell align="center" valign="middle"><em>Total</em></cell> + </row> + + <!-- PRETTY --> + <row> + <cell align="left" valign="middle">pretty</cell> + <cell align="right" valign="middle">336</cell> + <cell align="right" valign="middle">22</cell> + <cell align="right" valign="middle">76</cell> + <cell align="right" valign="middle">98</cell> + </row> + <row> + <cell align="left" valign="middle">pretty [flex]</cell> + <cell align="right" valign="middle">336</cell> + <cell align="right" valign="middle">22 (22)</cell> + <cell align="right" valign="middle">41 (40)</cell> + <cell align="right" valign="middle">63 (62)</cell> + </row> + + <!-- COMPACT --> + <row> + <cell align="left" valign="middle">compact</cell> + <cell align="right" valign="middle">181</cell> + <cell align="right" valign="middle">19</cell> + <cell align="right" valign="middle">63</cell> + <cell align="right" valign="middle">82</cell> + </row> + <row> + <cell align="left" valign="middle">compact [flex]</cell> + <cell align="right" valign="middle">181</cell> + <cell align="right" valign="middle">19 (19)</cell> + <cell align="right" valign="middle">38 (36)</cell> + <cell align="right" valign="middle">57 (55)</cell> + </row> + + <!-- PER --> + <row> + <cell align="left" valign="middle">per bin</cell> + <cell align="right" valign="middle">91</cell> + <cell align="right" valign="middle">63</cell> + <cell align="right" valign="middle">69</cell> + <cell align="right" valign="middle">132</cell> + </row> + <row> + <cell align="left" valign="middle">per bin [driver]</cell> + <cell align="right" valign="middle">91</cell> + <cell align="right" valign="middle">43</cell> + <cell align="right" valign="middle">45</cell> + <cell align="right" valign="middle">88</cell> + </row> + <row> + <cell align="left" valign="middle">per bin [native]</cell> + <cell align="right" valign="middle">91</cell> + <cell align="right" valign="middle">47</cell> + <cell align="right" valign="middle">51</cell> + <cell align="right" valign="middle">99</cell> + </row> + <row> + <cell align="left" valign="middle">per bin [driver,native]</cell> + <cell align="right" valign="middle">91</cell> + <cell align="right" valign="middle">26</cell> + <cell align="right" valign="middle">29</cell> + <cell align="right" valign="middle">55</cell> + </row> + + <!-- BER --> + <row> + <cell align="left" valign="middle">ber bin</cell> + <cell align="right" valign="middle">165</cell> + <cell align="right" valign="middle">35</cell> + <cell align="right" valign="middle">42</cell> + <cell align="right" valign="middle">77</cell> + </row> + <row> + <cell align="left" valign="middle">ber bin [driver]</cell> + <cell align="right" valign="middle">165</cell> + <cell align="right" valign="middle">35</cell> + <cell align="right" valign="middle">37</cell> + <cell align="right" valign="middle">72</cell> + </row> + <row> + <cell align="left" valign="middle">ber bin [native]</cell> + <cell align="right" valign="middle">165</cell> + <cell align="right" valign="middle">19</cell> + <cell align="right" valign="middle">26</cell> + <cell align="right" valign="middle">45</cell> + </row> + <row> + <cell align="left" valign="middle">ber bin [driver,native]</cell> + <cell align="right" valign="middle">165</cell> + <cell align="right" valign="middle">19</cell> + <cell align="right" valign="middle">20</cell> + <cell align="right" valign="middle">39</cell> + </row> + + <!-- ERLANG --> + <row> + <cell align="left" valign="middle">erl_dist</cell> + <cell align="right" valign="middle">875</cell> + <cell align="right" valign="middle">5</cell> + <cell align="right" valign="middle">10</cell> + <cell align="right" valign="middle">15</cell> + </row> + <row> + <cell align="left" valign="middle">erl_dist [megaco_compressed]</cell> + <cell align="right" valign="middle">405</cell> + <cell align="right" valign="middle">6</cell> + <cell align="right" valign="middle">7</cell> + <cell align="right" valign="middle">13</cell> + </row> + <row> + <cell align="left" valign="middle">erl_dist [compressed]</cell> + <cell align="right" valign="middle">345</cell> + <cell align="right" valign="middle">86</cell> + <cell align="right" valign="middle">21</cell> + <cell align="right" valign="middle">107</cell> + </row> + <row> + <cell align="left" valign="middle">erl_dist [megaco_compressed,compressed]</cell> + <cell align="right" valign="middle">200</cell> + <cell align="right" valign="middle">71</cell> + <cell align="right" valign="middle">12</cell> + <cell align="right" valign="middle">83</cell> + </row> + + <tcaption>Codec performance</tcaption> + </table> + </section> + + <section> + <title>System performance characteristics</title> + <p>This is primarily a way to show the effects of using the + reentrant flex scanner instead of the non-reentrant. </p> + <p>As can be seen from the figures above there is no real difference + between a non-reentrant and an reentrant flex scanner when it + comes to the decode times of an individual message. </p> + <p>The real difference is instead in system characteristics, which + is best shown with the mstone1 test. </p> + <p>When running SMP erlang on a multi-core machine the "throughput" + is significantly higher. The mstone1 test is an extreme test, + but it shows what is gained by using the reentrant flex-scanner. </p> + <image file="mstone1.gif"> + <icaption>MStone1 with mstone1.sh -d flex -s 8</icaption> + </image> + </section> + + <section> + <title>Description of encoders/decoders</title> + <p>In Appendix A of the Megaco/H.248 specification (RFC 3525), there are + about 30 messages that shows a representative call flow. We have also + added a few extra version 1, version 2 and version 3 messages. + We have used these messages as basis for our measurements. + Our figures have not been weighted in regard to how frequent + the different kinds of messages that are sent between the media + gateway and its controller.</p> + <p>The test compares the following encoder/decoders:</p> + <list type="bulleted"> + <item> + <p><em>pretty</em> - pretty printed text. In the text encoding, + the protocol stack implementors have the choice of using a + mix of short and long keywords. It is also possible to add + white spaces to improve readability. The pretty text encoding + utilizes long keywords and an indentation style like the + text examples in the Megaco/H.248 specification.</p> + </item> + <item> + <p><em>compact</em> - the compact text encoding uses the shortest + possible keywords and no optional white spaces.</p> + </item> + <item> + <p><em>ber</em> - ASN.1 BER.</p> + </item> + <item> + <p><em>per</em> - ASN.1 PER. Not standardized as a valid + Megaco/H.248 encoding, but included for the matter of completeness + as its encoding is extremely compact.</p> + </item> + <item> + <p><em>erl_dist</em> - Erlang's native distribution format. Not + standardized as a valid Megaco/H.248 encoding, but included + as a reference due to its well known performance characteristics. + Erlang is a dynamically typed language and any Erlang data + structure may be serialized to the erl_dist format by using + built-in functions.</p> + </item> + </list> + <p>The actual encoded messages have been collected in one directory per + encoding type, containing one file per encoded message.</p> + <p>Here follows an example of a text message to give a feeling of the + difference between the pretty and compact versions of text messages. + First the pretty printed, well indented version with long keywords:</p> + <p></p> + <pre> +MEGACO/1 [124.124.124.222] + Transaction = 9998 { + Context = - { + ServiceChange = ROOT { + \011Services { + \011 Method = Restart, + \011 ServiceChangeAddress = 55555, + \011 Profile = ResGW/1, + \011 Reason = "901 MG Cold Boot" + \011} + } + } + } </pre> + <p>Then the compact text version without indentation and with short + keywords:</p> + <pre> +!/1 [124.124.124.222] T=9998{ + C=-{SC=ROOT{SV{MT=RS,AD=55555,PF=ResGW/1,RE="901 MG Cold Boot"}}}} </pre> + </section> + + <section> + <title>Setup</title> + <p>The measurements has been performed on a + Dell PowerEdge 1950iii with + 2* Intel Xeon L5430 @ 2.66 GHz, with 8 GB memory and + running SLES 10 SP2 x86_64, kernel 2.6.16.60-0.34-smp. + Software versions was open source OTP R13B and megaco-3.11.</p> + </section> + + <section> + <title>Summary</title> + <p>In our measurements we have seen that there are no significant + differences in message sizes between ASN.1 BER and the compact + text format. Some care should be taken when using the pretty text + style (which is used in all the examples included in the protocol + specification and preferred during debugging sessions) since the + messages can then be quite large. If the message size really is a + serious issue, our per encoder should be used, as the ASN.1 PER + format is much more compact than all the other alternatives. Its + major drawback is that it is has not been approved as a valid + Megaco/H.248 message encoding.</p> + + <p>When it comes to pure encode/decode performance, it turns out that:</p> + <list type="bulleted"> + <item> + <p>our fastest binary encoder (ber) is about equal + to our fastest text encoder (compact). </p> + </item> + <item> + <p>our fastest binary decoder (ber) is about 47% (44%) faster than our + fastest text decoder (compact). </p> + </item> + </list> + + <p>If the pure encode/decode performance really is a serious issue, our + erl_dist encoder could be used, as the encoding/decoding of the + erlang distribution format is much faster than all the other + alternatives. Its major drawback is that it is has not been approved + as a valid Megaco/H.248 message encoding.</p> + + <p>There is no performance advantage of building (and using) a + non-reentrant flex scanner over a reentrant flex scanner (if flex + supports building such a scanner). </p> + + <note> + <p>Please, observe that these performance figures are related to our + implementation in Erlang/OTP. Measurements of other implementations + using other tools and techniques may of course result in other + figures. </p> + </note> + </section> +</chapter> + |