cacheSPM: a static partition for shared cache in mixed-time-sensitive system with balanced performance

In modern safety-critical embedded systems (e.g., automotive/avionic systems), it is increasingly important to integrate components with different critical levels into one physical platform considering space, weight, and heat generation. The most common case is a mixed-time-sensitive system (MTSS), which is usually composed of a RTOS (Real-Time Operating System) and a GPOS (General-Purpose Operating System). In MTSS, cache sharing between RTOS and GPOS often causes inter-task interference, making WCET estimation overly pessimistic due to the increase of cache miss rate and task execution time variances. The existing cache management solutions, such as dynamic and static schemes, are challenging to be applied to MTSS directly. In this paper, we propose a novel practical method, termed cacheSPM, to eliminate the cache interference in MTSS. CacheSPM statically partitions cache resources during the compilation phase, effectively preventing the GPOS from influencing the cache resources belonged to the RTOS. Compared to the traditional partition schemes, cacheSPM has no intervention of memory manager and additional runtime overhead. Evaluation reveals that this method improves the memory utilization and reduces overhead in a balanced way, with the memory access latency reduced by 80.7% on average, and guarantee the real-time capability of RTOS without negatively affecting the performance of GPOS.