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Building Unreliable Systems out of Reliable Components: The Real Time Story
Edward A. Lee

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

Citation formats  
  • 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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