Operating System Support for Coexistence of Real-Time and Conventional Scheduling

  • Authors:
  • David B. Golub

  • Affiliations:
  • -

  • Venue:
  • Operating System Support for Coexistence of Real-Time and Conventional Scheduling
  • Year:
  • 1994

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Abstract

The advent of multimedia calls for new scheduling paradigms to handle the combination of time-critical and conventional applications present on many multimedia systems. The scheduler of the Mach 3.0 Microkernel has been rewritten to allow a wide spectrum of scheduling policies, from real-time through time-sharing to background, to be selected simultaneously for different tasks executing on the same processor. Scheduling policies can be set for a task or for individual threads within the task. The set of scheduling policies allowed on a processor or set of processors may be dynamically altered. Scheduling parameters can be set individually for each thread, task, or scheduling policy enabled on a processor. Each scheduling policy may have its own format for parameters; they are not limited to integer priorities. New scheduling policies may be configured into a kernel and may be ordered in any way desired. The resulting system provides enough flexibility for experimentation with new scheduling regimes, yet is efficient enough to allow a reasonable number of scheduling policies to coexist. When configured with both real-time and timesharing schedulers, the system smoothly supports both conventional and time-critical applications.