Multiple CPUs and GPUs are integrated on the same chip to share memory, and access requests between cores are interfering with each other. Memory requests from the GPU seriously interfere with the CPU memory access performance. Requests between multiple CPUs are intertwined when accessing memory, and its performance is greatly affected. The difference in access latency between GPU cores increases the average latency of memory accesses. In order to solve the problems encountered in the shared memory of heterogeneous multi-core systems, we propose a step-by-step memory scheduling strategy, which improve the system performance. The step-by-step memory scheduling strategy first creates a new memory request queue based on the request source and isolates the CPU requests from the GPU requests when the memory controller receives the memory request, thereby preventing the GPU request from interfering with the CPU request. Then, for the CPU request queue, a dynamic bank partitioning strategy is implemented, which dynamically maps it to different bank sets according to different memory characteristics of the application, and eliminates memory request interference of multiple CPU applications without affecting bank-level parallelism. Finally, for the GPU request queue, the criticality is introduced to measure the difference of the memory access latency between the cores. Based on the first ready-first come first served strategy, we implemented criticality-aware memory scheduling to balance the locality and criticality of application access.

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With more cores integrated into a single chip and the fast growth of main memory capacity, the DRAM memory design faces ever increasing challenges. Previous studies have shown that DRAM can consume up to 40% of the system power, which makes DRAM a major factor constraining the whole system’s growth in performance. Moreover, memory accesses from different applications are usually interleaved and interfere with each other, which further exacerbates the situation in memory system management. Therefore, reducing memory power consumption has become an urgent problem to be solved in both academia and industry. In this paper, we first proposed a novel strategy called Dynamic Bank Partitioning (DBP), which allocates banks to different applications based on their memory access characteristics. DBP not only effectively eliminates the interference among applications, but also fully takes advantage of bank level parallelism. Secondly, to further reduce power consumption, we propose an adaptive method to dynamically select an optimal page policy for each bank according to the characteristics of memory accesses that each bank receives. Our experimental results show that our strategy not only improves the system performance but also reduces the memory power consumption at the same time. Our proposed scheme can reduce memory power consumption up to 21.2% (10% on average across all workloads) and improve the performance to some extent. In the case that workloads are built with mixed applications, our scheme reduces the power consumption by 14% on average and improves the performance up to 12.5% (3% on average).

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