X A Real-Time Multi-Channel Memory Controller and Optimal Mapping of Memory Clients to Memory Channels

Ever increasing demands for main memory bandwidth and memory speed/power trade-off led to the introduction of memories with multiple memory channels, such as Wide IO DRAM. Efficient utilization of a multi-channel memory as a shared resource in multi-processor real-time systems depends on mapping of the memory clients to the memory channels according to their requirements on latency, bandwidth, communication and memory capacity. However, there is currently no real-time memory controller for multi-channel memories, and there is no methodology to optimally configure multi-channel memories in real-time systems. As a first work towards this direction, we present two main contributions in this article: 1) A configurable real-time multi-channel memory controller architecture with a novel method for logical-to-physical address translation. 2) Two design-time methods to map memory clients to the memory channels, one an optimal algorithm based on an integer programming formulation of the mapping problem, and the other a fast heuristic algorithm. We demonstrate the real-time guarantees on bandwidth and latency provided by our multi-channel memory controller architecture by experimental evaluation. Furthermore, we compare the performance of the mapping problem formulation in a solver and the heuristic algorithm against two existing mapping algorithms in terms of computation time and mapping success ratio. We show that an optimal solution can be found in 2 hours using the solver and in less than 1 second with less than 7%mapping failure using the heuristic for realistically sized problems. Finally, we demonstrate configuring a Wide IO DRAM in a High-Definition (HD) video and graphics processing system to emphasize the practical applicability and effectiveness of this work.