PWCET: Power-Aware Worst Case Execution Time Analysis

Worst case execution time (WCET) analysis is used to verify that real-time tasks on systems can be executed without violating any timing constraints. Power consumption is not considered in most of the WCET research work. However, real-time embedded systems have limited power resources and the leakage power cost by the cache could take up to 40% of the total power consumption. Because of the nature of data reuse in programs, not all of the cache may be needed during the execution. Traditional WCET analysis, which derives the WCET bound by assuming all cache is utilized, results in higher power dissipation. In this paper, we propose a Power-aware WCET analysis framework (PWCET) to improve energy efficiency by reducing cache size with no penalty on the WCET result. A compiler analysis based useful cache calculation algorithm is used to determine the non-useful cache size to be turned off to save power. Experiments on benchmarks demonstrate the effectiveness of the PWCET framework in obtaining considerable power savings without any effect on WCET bounds.