M2S-Cgm: A Detailed Architectural Simulator For Coherent Cpu-Gpu Systems

We introduce M2S-CGM a detailed architectural simulator that models the interactions between CPUs and GPUs operating in coherent heterogeneous compute environments. M2S-CGM extends an existing and established x86 CPU model and Southern Islands GPU model, adds a new custom-built memory system model and switching fabric called CGM, and incorporates a well-known SDRAM model. The CGM memory system simulator provides configurable entire system simulation and can support a range of non-coherent and coherent CPU-GPU configurations. M2S-CGM supports the runtime for OpenCL-based benchmarks in addition to traditional multithreaded CPU benchmarks and can run benchmarks from established heterogeneous benchmark collections. This allows us to experiment with different coherent CPU-GPU configurations and propose effective future improvements in these systems. We present the makeup of M2S-CGM\u27s software architectural design, provide a validation of the simulator, and provide coherent CPU-GPU execution results. Our validation results show average differences between our physical test system and M2S-CGM, of 10.4%, 22%, and 6.4% for 2 threaded, 4 threaded, and heterogeneous benchmark runs respectively. Our coherent CPU-GPU experimental results show an average speedup of 2.8 for our benchmarks over the baseline noncoherent system