Cache coherence strategies in a many-core processor

Abstract

Caches are frequently employed in memory systems, exploiting memory locality to gain advantages in high-speed performance and low latency. However, as computer processor core counts increase, maintaining coherence between caches becomes increasingly difficult. Current methods of cache coherence work well in small-scale multi-core processors, however, the viability of cache coherence as processors scale to thousands of cores remains an open question. A novel many-core execution-driven performance simulator, called Graphite and implemented by the Carbon group, has been utilized to study a variety of cache coherency strategies of processors up to 256 cores. Results suggest that cache coherence may be possible in future many-core processors, but that software developers will have to exercise great care to match their algorithms to the target architecture to avoid sub-optimal performance.