Citation
Edward A. Lee. "Repeatable Timing in Software and Networks". Talk or presentation, 9, October, 2011; ESWEEK 2011 Tutorial on Time-Predictable and Composable Architectures for Dependable Embedded Systems
Taipei, Taiwan.

Abstract
All widely used software abstractions lack temporal semantics. The notion of correct execution of a program written in every widely-used programming language today does not depend on the temporal behavior of the program. But temporal behavior matters in almost all systems. Even in systems with no particular real-time requirements, timing of programs is relevant to the value delivered by programs, and in the case of concurrent programs, also affects the functionality. In systems with real-time requirements, such as most cyber-physical systems, temporal behavior affects not just the value delivered by a system but also its correctness.

In this talk, we will argue that time can and must become part of the semantics of programs for a large class of applications. To illustrate that this is both practical and useful, we will describe two recent efforts at Berkeley in the design and implementation of timing-centric software systems. On the design side, we will describe PTIDES, a programming model for distributed real-time systems. PTIDES rests on a rigorous semantics of discrete-event systems and reflects the realities in distributed real-time, where measuring the passage of time is imperfect. PTIDES enables deterministic time-sensitive distributed actions. It relies on certain assumptions about networks that are not trivial (time synchronization with bounded error and bounded latency), but which have been shown in some contexts to be achievable and economical. PTIDES is also robust to subsystem failures, and, perhaps most interestingly, provides a semantic basis for detecting such failures at the earliest possible time. On the implementation side, we will describe PRET machines, which redefine the instruction-set architecture (ISA) of a microprocessor to include temporal semantics.

Electronic downloads

• ESWEEK_RepeatableTiming_Tutorial.pdf · application/pdf · 6276 kbytes

• HTML

  Edward A. Lee. <a
  href="http://chess.eecs.berkeley.edu/pubs/865.html"
  ><i>Repeatable Timing in Software and
  Networks</i></a>, Talk or presentation,  9,
  October, 2011; ESWEEK 2011 Tutorial on Time-Predictable and
  Composable Architectures for Dependable Embedded Systems
  <br>
  Taipei, Taiwan.

• Plain text

  Edward A. Lee. "Repeatable Timing in Software and
  Networks". Talk or presentation,  9, October, 2011;
  ESWEEK 2011 Tutorial on Time-Predictable and Composable
  Architectures for Dependable Embedded Systems
  <br>
  Taipei, Taiwan.

• BibTeX

  @presentation{Lee11_RepeatableTimingInSoftwareNetworks,
      author = {Edward A. Lee},
      title = {Repeatable Timing in Software and Networks},
      day = {9},
      month = {October},
      year = {2011},
      note = {ESWEEK 2011 Tutorial on Time-Predictable and
                Composable Architectures for Dependable Embedded
                Systems
  <br>
  Taipei, Taiwan},
      abstract = {All widely used software abstractions lack
                temporal semantics. The notion of correct
                execution of a program written in every
                widely-used programming language today does not
                depend on the temporal behavior of the program.
                But temporal behavior matters in almost all
                systems. Even in systems with no particular
                real-time requirements, timing of programs is
                relevant to the value delivered by programs, and
                in the case of concurrent programs, also affects
                the functionality. In systems with real-time
                requirements, such as most cyber-physical systems,
                temporal behavior affects not just the value
                delivered by a system but also its correctness.
                <p>In this talk, we will argue that time can and
                must become part of the semantics of programs for
                a large class of applications. To illustrate that
                this is both practical and useful, we will
                describe two recent efforts at Berkeley in the
                design and implementation of timing-centric
                software systems. On the design side, we will
                describe PTIDES, a programming model for
                distributed real-time systems. PTIDES rests on a
                rigorous semantics of discrete-event systems and
                reflects the realities in distributed real-time,
                where measuring the passage of time is imperfect.
                PTIDES enables deterministic time-sensitive
                distributed actions. It relies on certain
                assumptions about networks that are not trivial
                (time synchronization with bounded error and
                bounded latency), but which have been shown in
                some contexts to be achievable and economical.
                PTIDES is also robust to subsystem failures, and,
                perhaps most interestingly, provides a semantic
                basis for detecting such failures at the earliest
                possible time. On the implementation side, we will
                describe PRET machines, which redefine the
                instruction-set architecture (ISA) of a
                microprocessor to include temporal semantics.},
      URL = {http://chess.eecs.berkeley.edu/pubs/865.html}
  }
  

Posted by Mary Stewart on 26 Oct 2011.
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