Citation
Edward A. Lee. "Building Unreliable Systems out of Reliable Components: The Real Time Story". Technical report, EECS Dept., University of California, Berkeley, 5, October, 2005.

Abstract
Despite considerable progress in software and hardware techniques, when embedded computing systems absolutely must meet tight timing constraints, many of the advances in computing become part of the problem rather than part of the solution. The underlying technology for computation, synchronous digital logic, easily delivers precise timing determinacy (although certain deep submicron techniques threaten even this foundation). However, advances in computer architecture and software have made it difficult or impossible to estimate or predict the execution time of software. Moreover, networking techniques introduce variability and stochastic behavior, and operating systems rely on best effort techniques. Worse, programming languages lack time in their semantics, so timing requirements are only specified indirectly. I examine the following question: "if precise timeliness in a networked embedded system is absolutely essential, what has to change?" The answer, unfortunately, is "nearly everything."

Electronic downloads

• http://www.eecs.berkeley.edu/Pubs/TechRpts/2005/EECS-2005-5.html
• http://www.embeddedcomponents.com/marketplace/enablers/berkeley/eecs/PtolemyII/. (Video presentation of similar material [registration required])
• http://chess.eecs.berkeley.edu/pubs/358.html. (Presentation of this material)

• HTML

  Edward A. Lee. <a
  href="http://chess.eecs.berkeley.edu/pubs/56.html"
  ><i>Building Unreliable Systems out of Reliable
  Components:  The Real Time Story</i></a>,
  Technical report,  EECS Dept., University of California,
  Berkeley, 5, October, 2005.

• Plain text

  Edward A. Lee. "Building Unreliable Systems out of
  Reliable Components:  The Real Time Story". Technical
  report,  EECS Dept., University of California, Berkeley, 5,
  October, 2005.

• BibTeX

  @techreport{Lee05_BuildingUnreliableSystemsOutOfReliableComponentsReal,
      author = {Edward A. Lee},
      title = {Building Unreliable Systems out of Reliable
                Components:  The Real Time Story},
      institution = {EECS Dept., University of California, Berkeley},
      number = {5},
      month = {October},
      year = {2005},
      abstract = {Despite considerable progress in software and
                hardware techniques, when embedded computing
                systems absolutely must meet tight timing
                constraints, many of the advances in computing
                become part of the problem rather than part of the
                solution. The underlying technology for
                computation, synchronous digital logic, easily
                delivers precise timing determinacy (although
                certain deep submicron techniques threaten even
                this foundation). However, advances in computer
                architecture and software have made it difficult
                or impossible to estimate or predict the execution
                time of software. Moreover, networking techniques
                introduce variability and stochastic behavior, and
                operating systems rely on best effort techniques.
                Worse, programming languages lack time in their
                semantics, so timing requirements are only
                specified indirectly. I examine the following
                question: "if precise timeliness in a networked
                embedded system is absolutely essential, what has
                to change?" The answer, unfortunately, is "nearly
                everything."},
      URL = {http://chess.eecs.berkeley.edu/pubs/56.html}
  }
  

Posted by Mary Stewart on 4 May 2006.
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