Dynamically configurable shared CMP helper engines for improved performance

Abstract

Technology scaling trends have forced designers to consider alternatives to deeply pipelining aggressive cores with large amounts of performance accelerating hardware. One alternative is a small, simple core that can be augmented with latency tolerant helper engines. As the demands placed on the processor core varies between applications, and even between phases of an application, the benefit seen from any set of helper engines will vary tremendously. If there is a single core, these auxiliary structures can be turned on and off dynamically to tune the energy/performance of the machine to the needs of the running application.As more of the processor is broken down into helper engines, and as we add more and more cores onto a single chip which can potentially share helpers, the decisions that are made about these structures become increasingly important. In this paper we describe the need for methods that effectively manage these helper engines. Our counter-based approach can dynamically turn off 3 helpers on average, while staying within 2% of the performance when running with all helpers. In a multicore environment, our intelligent and flexible sharing of helper engines, provides an average 24% speedup over static sharing in conjoined cores. Furthermore we show benefit from constructively sharing helper engines among multiple cores running the same application.