Timing analysis of PCM main memory in multicore systems

Given that power is one of the biggest concerns of embedded systems, many devices have replaced DRAM with non-volatile Phase Change Memories (PCM). Some applications need to adhere to strict timing constraints and thus their temporal behavior must be analyzed before deploying them. Moreover, modern systems typically contain multiple cores, causing an application to incur significant delays due to the contention for the shared bus and shared main memory (PCM in this work). One of the challenges in the timing analysis for PCM main memories is the high discrepancy between read and write latencies and the high contention among cores. Finding an upper bound on these delays is non-trivial mainly because (i) memory requests may be issued by co-executing applications at random times, (ii) it is difficult to determine apriori which applications will be concurrently executing, and (iii) the type of requests applications will issue. This work proposes a method to derive upper bounds on the increase in execution time of applications executing on such PCM-based multicores. It considers the contention on the shared memory and focuses on dealing with the asymmetric read and write latencies of PCM-based memories, while taking into account the specific policy applied to schedule requests by the memory controller.