Cache-Aware SPM Allocation to Reduce Worst-Case Execution Time for Hybrid SPM-Caches

Abstract

Scratch-Pad Memories (SPMs) have been increasingly used in real-time and embedded systems. However, it is still unknown and challenging to reduce the worst-case execution time (WCET) for hybrid SPM-cache architecture, where an SPM and a cache memory are placed on-chip in parallel to cooperatively improve performance and/or energy efficiency. In this paper, we study four SPM allocation strategies to reduce the WCET for hybrid SPM-caches with different complexities. These algorithms differ by whether or not they can cooperate with the cache or be aware of the WCET. Our evaluation shows that the cache-aware and WCET-oriented SPM allocation can minimize the WCET for real-time benchmarks with little or even positive impact on the average-case execution time (ACET).