episode-58.xml

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<item xmlns:itunes="http://www.itunes.com/dtds/podcast-1.0.dtd">
  <title>Toward Leaner, Faster ovn-northd</title>
  <guests>Leonid Ryzhyk from VMware Research Group</guests>
  <description>
    <p>
      Leonid Ryzhyk is a senior researcher in the VMware Research Group.  The
      main theme of his work is applying formal methods to build better
      operating systems and networks.  Before joining VMware, Leonid received
      his PhD from University of New South Wales and NICTA.  Leonid has also
      worked as a researcher at NICTA, as a postdoc at University of Toronto
      and at Carnegie Mellon University, and as a researcher at Samsung
      Research America.
    </p>

    <p>
      In OVN, the <code>ovn-northd</code> daemon acts as an interface and a
      translator between OVN's northbound and southbound databases.  With the
      existing implementation, any change in the northbound database causes
      <code>ovn-northd</code> to do a full recomputation of the complete
      contents of the southbound database.  For a large network, this is
      slow&#8212;it can take multiple seconds of CPU time&#8212;regardless of
      the size of the change in the northbound database.  Therefore, even a
      small change, such as adding or removing a single port or a single VM,
      can take a relatively long time to be realized in the network.
    </p>

    <p>
      In this talk, Leonid presents a prototype for a solution to the problem.
      The solution implements incremental computation using a system called <a
      href="https://github.com/frankmcsherry/differential-dataflow/blob/master/differentialdataflow.pdf">Differential
      Dataflow</a>, which is based on the <a
      href="https://en.wikipedia.org/wiki/Datalog">Datalog</a> language for
      database queries.  Because Datalog is not a particularly friendly
      language for developers who are not already accustomed to it, Leonid also
      layered syntactic sugar over it called FTL, for Flow Template Language,
      which is inspired by the <a
      href="https://en.wikipedia.org/wiki/FLWOR">FLWOR</a> syntax from <a
      href="https://en.wikipedia.org/wiki/XQuery">XQuery</a>.
    </p>

    <p>
      Some of the talk is easier to follow if you view the slides (<a
      href="episode-58-slides.pdf">PDF</a>).
    </p>

    <p>
      You can contact Leonid via email at <a
      href="mailto:lryzhyk@vmware.com">lryzhyk@vmware.com</a>.
    </p>

    <p>
      Leonid previously appeared in OVS Orbit in <a href="#e44">episode 44</a>
      on the Cocoon-2 network programming system.  <a href="#e5">Episode 5</a>,
      with Teemu Koponen and Yusheng Wang, touched on related concepts with its
      coverage of the nlog language which is also based on Datalog.
    </p>

    <p class="attribution">
      OVS Orbit is produced by <a href="mailto:blp@ovn.org">Ben Pfaff</a>.  The
      intro music in this episode is <a
      href="http://dig.ccmixter.org/files/AlexBeroza/43098">Drive</a>,
      featuring cdk and DarrylJ, copyright 2013, 2016 by Alex.  The bumper
      music is <a href="http://dig.ccmixter.org/files/speck/42100">Yeah Ant</a>
      featuring Wired Ant and Javolenus, copyright 2013 by Speck.  The outro
      music is <a href="http://dig.ccmixter.org/files/Kirkoid/43005">Space
      Bazooka</a> featuring Doxen Zsigmond, copyright 2013 by Kirkoid.  All
      content is licensed under a Creative Commons <a
      href="http://creativecommons.org/licenses/by/3.0/">Attribution 3.0
      Unported (CC BY 3.0)</a> license.
    </p>
  </description>
  <pubDate>Tue, 22 May 2018 20:37:16 GMT</pubDate>
</item>