Branch Prediction directed Dynamic instruction Cache Locking for embedded systems

Abstract

Cache locking is a cache management technique to preclude the replacement of locked cache contents. Cache locking is often used to improve cache access predictability in Worst-Case Execution Time (WCET) analysis. Static cache locking methods have been proposed recently to improve average system performance. This paper presents an approach, Branch Prediction directed Dynamic Cache Locking (BPDCL), to improve average system performance through effective cache conflict miss reduction in different execution regions. In this proposed approach, the control flow graph of a program is partitioned into regions and memory blocks worth locking for each region are calculated during compilation time. At runtime, directed by branch predictions, locking routines are prefetched into a high-speed buffer. The pre-determined cache locking contents are loaded and locked at specific execution points during program execution. Experimental results show that the proposed BPDCL method exhibits an average improvement of 21.8% and 10.3% on cache miss rate reduction in comparison to the case with no cache locking and the static locking method respectively.