Technical Report : CS - TR - 2006 - 001 Reliability - Aware Dynamic Energy Management in Dependable Embedded Real - Time Systems ∗

Recent studies show that, voltage scaling, which is an efficient energy management technique, has a direct and negative effect on system reliability because of the increased rate of transient faults (e.g., those induced by cosmic particles). In this work, we propose energy management schemes that explicitly take system reliability into consideration. The proposed reliability-aware energy management schemes dynamically schedule recoveries for tasks to be scaled down to recuperate the reliability loss due to energy management. Based on the amount of available slack, the application size and the fault rate changes, we analyze when it is profitable to reclaim the slack for energy savings without sacrificing system reliability. Checkpoint technique is further explored to efficiently use the slack. Analytical and simulation results show that, the proposed schemes can achieve comparable energy savings as ordinary energy management schemes while preserving system reliability. The ordinary energy management schemes that ignore the effects of voltage scaling on fault rate changes could lead to drastically decreased system reliability.