Experiences in Implementing an Energy-Driven Task Scheduler in RT-Linux

  • Authors:
  • Vishnu Swaminathan;Charles B. Schweizer;Krishnendu Chakrabarty;Amil A. Patel

  • Affiliations:
  • -;-;-;-

  • Venue:
  • RTAS '02 Proceedings of the Eighth IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS'02)
  • Year:
  • 2002

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Abstract

Dynamic voltage scaling (DVS) is being increasingly used for power management in embedded systems. Energy is a scarce resource in embedded real-time systems and energyconsumption must be carefully balanced against real-time responsiveness. We describe our experiences in implementing an energy driven task scheduler in RT-Linux. We attempt to minimize the energy consumed by a taskset while guaranteeing that all task deadlines are met. Our algorithm, which we call LEDF, follows a greedy approach and schedules as many tasks as possible at a low CPU speed in a power-aware manner. We present simulation results onenergy savings using LEDF, and we validate our approach using the RT-Linux testbed on the AMD Athlon 4 processor. Power measurements taken on the testbed closely match the power estimates obtained using simulation. Our results show that DVS results in significant energy savings for practical real-life task sets. We also show that when CPU speeds are restricted to only a few discrete values, this approach saves more energy than currently existing methods.