Reducing Shared Cache Contention by Scheduling Order Adjustment on Commodity Multi-cores

Due to the limitation of power and processor complexity on traditional single core processors, multi-core processors have become the mainstream. One key feature on commodity multi-cores is that the last level cache (LLC) is usually shared. However, the shared cache contention can affect the performance of applications significantly. Several existing proposals demonstrate that task co-scheduling has the potential to alleviate the contention, but it is challenging to make co-scheduling practical in commodity operating systems. In this paper, we propose two lightweight practical cache-aware co-scheduling methods, namely static SOA and dynamic SOA, to solve the cache contention problem on commodity multi-cores. The central idea of the two methods is that the cache contention can be reduced by adjusting the scheduling order properly. These two methods are different from each other mainly in the way of acquiring the process´s cache requirement. The static SOA (static scheduling order adjustment) method acquires the cache requirement information statically by offline profiling, while the dynamic SOA (dynamic scheduling order adjustment) captures the cache requirement statistics by using performance counters. Experimental results using multi-programmed NAS workloads suggest that the proposed methods can greatly reduce the effect of cache contention on multi-core systems. Specifically, for the static SOA method, the execution time can be reduced by up to 15.7%, the number of cache misses can be reduced by up to 11.8%, and the performance improvement remains obvious across the cache size and the length of time slice. For the dynamic SOA method, the execution time reduction can achieve up to 7.09%.