Microarchitectural performance comparison of Intel Knights Corner and Intel Sandy Bridge with CFD applications

This paper comparatively evaluates the microarchitectural performance of two representative Computational Fluid Dynamics (CFD) applications on the Intel Many Integrated Core (MIC) product, the Intel Knights Corner (KNC) coprocessor, and the Intel Sand Bridge (SNB) processor. Performance Monitoring Unit-based measurement method is used, along with a two-phase measurement method and some considerations to minimize the errors and instabilities. The results show that the CFD applications are sensitive to architecture factors. Their single thread performance and efficiency on KNC are much lower than that on SNB. Branch prediction and memory access are two primary factors that make the performance difference. The applications' low-computational intensity and inefficient vector instruction usage are two additional factors. To be more efficient for the CFD applications, the MIC architecture needs to improve its branch prediction mechanism and memory hierarchy. Fine tuning of application codes is also crucial and is hard work.