Back-end assignment schemes for clustered multithreaded processors

ABSTRACT

Power consumption and wire delays are two important limiting factors for current and forthcoming processors. Monolithic designs that keep reasonable power consumption and operate at high clock frequencies are ever harder to implement. In this paper we propose a novel multithreaded clustered microarchitecture that consists of a clustered front-end capable of fetching instructions from multiple hreads and a clustered back-end where instructions are executed. This microarchitecture combines the concepts of multithreading and clustering to a tack both problems: power consumption and wire delays. A key aspect of this microarchitecture is the assignment of resources to the simultaneously running threads. We propose two back-end assignment schemes; in the Static Back-end Assignment (SBA)the back-ends are statically assigned to the front-ends, while in the Dynamic Back-end Assignment (DBA) the back-ends are dynamically assigned according to the demands of each front-end. A limit study of the potential performance of DBA shows a minor benefit compared to SBA. The causes why the DBA scheme does not perform as initially expected are investigated and the main limiting factors of this architecture are evaluated. Finally,we point out he advantages of DBA versus SBA.

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INDEX TERMS

Primary Classification:
  C. Computer Systems Organization
  C.1 PROCESSOR ARCHITECTURES
      C.1.3 Other Architecture Styles
          Subjects: Adaptable architectures

General Terms:
Design, Performance

Keywords:
CMP, clustered, multithreaded, steering