Citation
Silviu Craciunas. "Programmable Temporal Isolation for Real-Time Systems". Talk or presentation, 30, November, 2010.

Abstract
We introduce a novel scheduling paradigm for hard real-time uniprocessor systems, called Variable-bandwidth Server (VBS), that enables adaptation of software processes to varying real-time constraints while maintaining temporal isolation. In the VBS process model, processes are sequences of individual actions with an action being a given piece of process code. Processes and actions are temporally isolated from one another in the sense that the variance in response times of the same action of a given process is bounded independently of any other concurrently running processes in the system. As the variance of action response times is also influenced by the scheduler overhead, we introduce a framework for overhead accounting in VBS-scheduled systems. Overhead introduced by the scheduling algorithm may be accounted for either by decreasing process execution speed to maintain CPU utilization, or by increasing CPU utilization to maintain process execution speed. Both methods can be combined by handling an arbitrary fraction of the total scheduler overhead with one method and the rest with the other. We also show that it is possible to reduce CPU power consumption with VBS by CPU voltage and frequency scaling. Scaling to lower frequencies is possible whenever there is CPU slack in the system. We propose a frequency-scaling VBS algorithm that exploits CPU slack to minimize operating frequencies with maximal CPU utilization while maintaining temporal isolation. This may lead to improvements in power consumption while hiding the real-time effects of frequency scaling. Additionally, we present more advanced methods with which additional power may be saved by redistributing computation time of individual process actions if the system has knowledge of future events.

Electronic downloads

• silviu_talk2010.pdf · application/pdf · 11221 kbytes

• HTML

  Silviu Craciunas. <a
  href="http://chess.eecs.berkeley.edu/pubs/789.html"
  ><i>Programmable Temporal Isolation for Real-Time
  Systems</i></a>, Talk or presentation,  30,
  November, 2010.

• Plain text

  Silviu Craciunas. "Programmable Temporal Isolation for
  Real-Time Systems". Talk or presentation,  30,
  November, 2010.

• BibTeX

  @presentation{Craciunas10_ProgrammableTemporalIsolationForRealTimeSystems,
      author = {Silviu Craciunas},
      title = {Programmable Temporal Isolation for Real-Time
                Systems},
      day = {30},
      month = {November},
      year = {2010},
      abstract = {We introduce a novel scheduling paradigm for hard
                real-time uniprocessor systems, called
                Variable-bandwidth Server (VBS), that enables
                adaptation of software processes to varying
                real-time constraints while maintaining temporal
                isolation. In the VBS process model, processes are
                sequences of individual actions with an action
                being a given piece of process code. Processes and
                actions are temporally isolated from one another
                in the sense that the variance in response times
                of the same action of a given process is bounded
                independently of any other concurrently running
                processes in the system. As the variance of action
                response times is also influenced by the scheduler
                overhead, we introduce a framework for overhead
                accounting in VBS-scheduled systems. Overhead
                introduced by the scheduling algorithm may be
                accounted for either by decreasing process
                execution speed to maintain CPU utilization, or by
                increasing CPU utilization to maintain process
                execution speed. Both methods can be combined by
                handling an arbitrary fraction of the total
                scheduler overhead with one method and the rest
                with the other. We also show that it is possible
                to reduce CPU power consumption with VBS by CPU
                voltage and frequency scaling. Scaling to lower
                frequencies is possible whenever there is CPU
                slack in the system. We propose a
                frequency-scaling VBS algorithm that exploits CPU
                slack to minimize operating frequencies with
                maximal CPU utilization while maintaining temporal
                isolation. This may lead to improvements in power
                consumption while hiding the real-time effects of
                frequency scaling. Additionally, we present more
                advanced methods with which additional power may
                be saved by redistributing computation time of
                individual process actions if the system has
                knowledge of future events.},
      URL = {http://chess.eecs.berkeley.edu/pubs/789.html}
  }
  

Posted by Jan Reineke on 1 Dec 2010.
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