A Performance Model for OpenMP Memory Bound Applications in Multisocket Systems

Abstract

The performance of OpenMP applications executed in multisocket multicore processors can be limited by the memory interface. In a multisocket environment, each multicore processor can present a performance degradation in memory-bound parallel regions when sharing the same Last Level Cache (LLC). We propose a characterization of the performance of parallel regions to estimate cache misses and execution time.This model is used to select the number of threads and affinity distribution for each parallel region. The model is applied for SP and MG benchmarks from the NAS Parallel Benchmark Suite using different workloads on two different multicore, multisocket systems.The results shown that the estimation preserves the behavior shown in measured executions for the affinity configurations evaluated. Estimated execution time is used to select a set of configurations in order to minimize the impact of memory contention, achieving significant improvements compared with a default configuration using all threads.