Bounding SDRAM Interference: Detailed Analysis vs. Latency-Rate Analysis
Hardik Shah, Alois Knoll, Benny Åkesson · 2015
Abstract—The transition towards multi-processor systems with shared resources is challenging for real-time systems, since resource interference between con-current applications must be bounded using timing analysis. There are two common approaches to this problem: 1) Detailed analysis that models the partic-ular resource and arbiter cycle-accurately to achieve tight bounds. 2) Using temporal abstractions, such as latency-rate (LR) servers, to enable unified analysis for different resources and arbiters using well-known tim-ing analysis frameworks. However, the use of abstrac-tion typically implies reducing the tightness of analysis that may result in over-dimensioned systems, although this pessimism has not been properly investigated. This paper compares the two approaches in terms of worst-case execution time (WCET) of applications sharing an SDRAM memory under Credit-Controlled Static-Priority (CCSP) arbitration. The three main contributions are: 1) A detailed interference analysis of the SDRAM memory and CCSP arbiter. 2) Based on the detailed analysis, two optimizations are proposed to the LR analysis that increase the tightness of its interference bounds. 3) An experimental comparison of the two approaches that quantifies their impact on the WCET of applications from the CHStone benchmark. I.