Method for optimizing memory controller placement in multi-core processors by determining a fitness metric based on a bottleneck link in a multiprocessor array

Abstract

The location of the memory controllers within the on-chip fabric of multiprocessor architectures plays a central role in latency bandwidth characteristics of the processor-to-memory traffic. Intelligent placement substantially reduces the maximum channel load depending on the specific memory controller configuration selected. A variety of simulation techniques are used along and in combination to determine optimal memory controller arrangements. Diamond-type and diagonal X-type memory controller configurations that spread network traffic across all rows and columns in a multiprocessor array substantially improve over other arrangements. Such placements reduce interconnect latency by an average of 10% for real workloads, and the small number of memory controllers relative to the number of on-chip cores opens up a rich design space to optimize latency and bandwidth characteristics of the on-chip network.