FC-AMAT: factor-based C-AMAT analysis in memory system measurement

Abstract

The “memory wall” problem has necessitated the introduction of more accurate memory metrics. C-AMAT, an extension of AMAT that considers memory access concurrency, can evaluate the performance of modern memory systems more accurately and comprehensively. However, compared to AMAT, calculating C-AMAT means additional complexity and more hardware resources, which incurs high overhead for this metric. In this paper, we propose FC-AMAT, an analysis model based on C-AMAT. We first explore the numerical relations between factors’ C-AMAT and overall C-AMAT, then try to use factor’s-first (changed factor or leading factor) C-AMAT to evaluate effects of changes applied to a memory system, which can not only reduce measurement overhead, but also guarantee acceptable evaluation accuracy through a rigorous check. Furthermore, we provide the method to determine the leading factor of a memory system. Simulations with varied configurations are conducted to study the numerical relations between factors’ C-AMAT and overall C-AMAT, as well as to evaluate the effects of FC-AMAT. Experimental results show that (1) parameters of factors’ C-AMAT have different influence degrees on overall C-AMAT, (2) the leading factor of a memory system remains unchanged across various configurations and (3) using factor’s C-AMAT as the evaluation metric reduces the hardware overhead for measurement, including detecting logic and storage cost, which demonstrates the effectiveness of FC-AMAT.