Memory latency effects in decoupled architectures with a single data memory module

Abstract

Decoupled computer architectures partition the memory access and execute functions in a computer program and achieve high performance by exploiting the fine-grain parallelism between the two. These architectures make use of an access processor to perform the data fetch ahead of demand by the execute process and hence are often less sensitive to memory access delays than conventional architectures. Past performance studies of decoupled computers used memory systems that are interleave or pipelined. We undertake a simulation study of the latency effects in decoupled computers when connected to a single, conventional non-interleaved data memory module so that the effect of decoupling is isolated from the improvement caused by interleaving. We compare decoupled computer performance to single processors with caches, study the memory latency sensitivity of the decoupled systems, and also perform simulations to determine the significance of data caches in a decoupled computer architecture. The Lawrence Livermore Loops and two signal processing algorithms are used as the simulation benchmark.