Set-associative cache-management method with parallel read and serial read pipelined with serial write

Abstract

A set-associative cache-management method combines one-cycle reads and two-cycle pipelined writes. The one-cycle reads involve accessing data from multiple sets in parallel before a tag match is determined. Once a tag match is determined, it is used to select the one of the accessed cache memory locations to be coupled to the processor for the read operation. The two-cycle write involves finding a match in a first cycle and performing the write in the second cycle. During the write, the first stage of the write pipeline is available to begin another write operation. Also, the first-stage of the pipeline can be used to begin a two-cycle read operation-which results in a power saving relative to the one-cycle read operation. Due to the pipeline, there is no time penalty involved in the two-cycle read performed after the pipelined write. Also, instead of a wait, a no-op can be executed in the first stage of the write pipeline while the second stage of the pipeline is fulfilling a write request.