A standby-sparing technique with low energy-overhead for fault-tolerant hard real-time systems

ABSTRACT

Time redundancy (rollback-recovery) and hardware redundancy are commonly used in real-time systems to achieve fault tolerance. From an energy consumption point of view, time redundancy is generally more preferable than hardware redundancy. However, hard real-time systems often use hardware redundancy to meet high reliability requirements of safety-critical applications. In this paper we propose a hardware-redundancy technique with low energy-overhead for hard real-time systems. The proposed technique is based on standby-sparing, where the system is composed of a primary unit and a spare. Through analytical models, we have developed an online energy-management method which uses a slack reclamation scheme to reduce the energy consumption of both the primary and spare units. In this method, dynamic voltage scaling (DVS) is used for the primary unit and dynamic power management (DPM) is used for the spare. We conducted several experiments to compare the proposed system with a fault-tolerant real-time system which uses time redundancy for fault tolerance and DVS with slack reclamation for low energy consumption. The results show that for relaxed time constraints, the proposed system provides up to 24% energy saving as compared to the time-redundancy system. For tight deadlines when the time-redundancy system can tolerate no faults, the proposed system preserves its fault-tolerance but with about 32% more energy consumption.

REFERENCES

• 1: V. Izosimov, P. Pop, P. Eles, and Z. Peng, "Scheduling of Fault-Tolerant Embedded Systems with Soft and Hard Timing Constraints", in Proc. Design, Automation and Test in Europe (DATE '08), pp. 915--920, March 2008.
• 2: R. Melhem, D. Mosse, and E. Elnozahy, "The interplay of power management and fault recovery in real-time systems," IEEE Trans. Computers, vol. 53, no. 2, pp. 217--231, 2004.
• 3: Y. Zhang and K. Chakrabarty, "Dynamic adaptation for fault tolerance and power management in embedded real-time systems," ACM Tran. Embedded Computing Systems, vol. 3, no. 2, pp. 336--360, 2004.
• 4: F. Liberato, R. Melhem, and D. Mosse, "Tolerance to multiple transient faults for aperiodic tasks in hard real-time systems," IEEE Trans. Computers, vol. 49, no. 9, pp. 906--914, 2000.
• 5: P. Eles, V. Izosimov, P. Pop, and Z. Peng, "Synthesis of Fault-Tolerant Embedded Systems", in Proc. Design, Automation and Test in Europe (DATE '08), pp. 1117--1122, March 2008.
• 6: A. Ejlali, B.M. Al-Hashimi, M.T. Schmitz, P. Rosinger, and S.G. Miremadi, "Combined Time and Information Redundancy for SEU-Tolerance in Energy-Efficient Real-Time Systems", IEEE Trans. VLSI Sys., vol. 14, no. 4, pp. 323--335, April 2006.
• 7: I. Koren, and C. M. Krishna, Fault-Tolerant Systems, Morgan Kaufmann, Elsevier, 2007.
• 8: Y. Zhang and K. Chakrabarty, "A Unified Approach for Fault Tolerance and Dynamic Power Management in Fixed-Priority Real-Time Embedded Systems", IEEE Trans. CAD, vol. 25, no. 1, pp. 111--125 JAN. 2006.
• 9: A. M. K. Cheng, Real-Time Systems, Scheduling, Analysis, and Verification, John Wiley & Sons, 2002.
• 10: M. T. Schmitz, B. M. Al-Hashimi, and P. Eles, System-Level Design Techniques for Energy-Efficient Embedded Systems, Norwell, MA: Kluwer, 2004.
• 11: T. D. Burd, T. A. Pering, A. J. Stratakos, and R. W. Brodersen, "A dynamic voltage scaled microprocessor system," IEEE J. Solid-State Circuits, vol. 35, no. 11, pp. 1571--1580, Nov. 2000.
• 12: K. Marti, Stochastic Optimization Methods, Second Edition, Springer, 2008.
• 13: P. Li, and B. Ravindran, "Fast, Best-Effort Real-Time Scheduling Algorithm", IEEE Trans. Copuuters, vol. 53, no. 9, Sept. 2004.
• 14: H. Aydin, R. Melhem, D. Mosse, and P. Mejia-Alvarez, "Power-Aware Scheduling for Periodic Real-Time Tasks", IEEE Trans. Computers, vol. 53, no. 5, May 2004.
• 15: D. Zhu, R. Melhem, D. Mosse, and E. Elnozahy, "Analysis of an energy efficient optimistic TMR scheme", in Proc. 10th Int'l Conf. Parallel and Distributed Systems (ICPADS 2004), pp. 559--568, July 2004.
• 16: S. Poledna, Fault-tolerant real-time systems: The problem of replica determinism, Kluwer Academic Publishers, 1996.
• 17: H. Kopetz, Real-time systems: Design principles for distributed embedded applications, Kluwer Academic Publishers, 2002.
• 18: D.K. Pradhan, Fault-tolerant computer system design, Prentice-Hall, 1996.
• 19: R. Jejurikar, and R. Gupta, "Dynamic slack reclamation with procrastination scheduling in real time embedded systems", in Proc. 42nd Design Automation Conference (DAC 2005), pp. 111--116, June 2005.
• 20: "TM5400/TM5600 Data Book", Transmeta Corp., Santa Clara, CA, 2000.
• 21: http://www-micrel.deis.unibo.it/sitonew/research/mparm.html
• 22: M. R. Guthaus, J. S. Ringenberg, D. Ernst,T. M. Austin, T. Mudge, and R. B. Brown, "MiBench: A free, commercially representative embedded benchmark suite", in Proc. IEEE 4th annual Workshop on Workload Characterization, pp. 83--94, 2001.
• 23: L. Benini, D. Bertozzi, A. Bogoliolo, F. Menichelli, and M. Olivieri., "MPARM: Exploring the Multi-Processor SoC Design Space with SystemC", The Journal of VLSI Signal Processing, vol. 41, no. 2, pp. 169--182, 2005.
• 24: http://www.rtems.com

INDEX TERMS

Primary Classification:
  B. Hardware
  B.8 Performance and Reliability
      B.8.1 Reliability, Testing, and Fault-Tolerance

Additional Classification:
  C. Computer Systems Organization
  C.3 SPECIAL-PURPOSE AND APPLICATION-BASED SYSTEMS

General Terms:
Design, Performance, Reliability

Keywords:
energy minimization, hard real-time systems, reliability