Abstract

Processors with write-through caches typically require a write buffer to hide the write latency to the next level of memory hierarchy and to reduce write trajgic. A write buffer can cause processor stalls when it isfull, when it contends with a cache miss for access to the next level of the hierarchy, and when it contains thefreshest copy of data needed by a load. This paper uses instructionlevel simulation of SPEC92 benchmarks to investigate how different write buffer depths, retirement policies, and load-hazard policies affect these three types of write-buffer stalls. Deeper buflers with adequate headroom, lazier retirement policies, and the ability to read data directly from the write buffer combine to substantially reduce write-buffer-induced stalls. 1

Citations