Optimization of Uncore Data Flow on NUMA Platform

Abstract : Uncore part of the processor has a profound effect, especially in NUMA systems, since it is used to connect cores, last level caches (LLC), on-chip multiple memory controllers (MCs) and high-speed interconnections. In our previous study, we investigated several benchmarks’ data flow in Uncore of Intel Westmere microarchitecture and found that the data flow of Global Queue (GQ) and QuickPath Home Logical (QHL) has serious imbalance and congestion problem. This paper, we aims at the problem of entries’ low efficiency in GQ and QHL we set up an M/M/3 Queue Model for GQ and QHL’s three trackers’ data flow, and then design a Dynamic Entries Management (DEM) mechanism which could improve entries’ efficiency dramatically. The model is implemented in Matlab to simulate two different data flow pattern. Experiment results shows that DEM mechanism reduces stall cycles of trackers significantly: DEM reduces almost 60% stall cycles under smooth request sequences; DEM mechanism reduces almost 20~30% stall cycles under burst request sequences.