A novel renaming mechanism that boosts software prefetching

  • Authors:
  • Daniel Ortega;Mateo Valero;Eduard Ayguadé

  • Affiliations:
  • Departamento de Arquitectura de Computadores, Univ ersidad Politécnica de Catalu~ na -- Barcelona, Spain;Departamento de Arquitectura de Computadores, Univ ersidad Politécnica de Catalu~ na -- Barcelona, Spain;Departamento de Arquitectura de Computadores, Univ ersidad Politécnica de Catalu~ na -- Barcelona, Spain

  • Venue:
  • ICS '01 Proceedings of the 15th international conference on Supercomputing
  • Year:
  • 2001

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Abstract

The detection and correct handling of data and control dependencies constitutes one of the biggest issues to expose ILP in current architectures. The ever increasing memory latencies and working space of programmes are making prefetching techniques crucial for the attainment of sustained high performance. Software prefetching allows the compiler to use information discovered at compile-time to effectively bring needed data before it is used, thus hiding all or part of the latency from main memory.On the other hand, renaming is a technique that allows the hardware to break register naming dependencies, thus exposing more parallelism to the hardware. In this paper we will present a new compiler-directed renaming mechanism focused on prefetch instructions. The compiler informs the hardware on the association of prefetch and load instructions, thus making it possible for the hardware to convert non-binding prefetches in to binding prefetches, without any of the compile-time limitations this other kind of prefetching may have.The mechanism can be implemented at a very low costin terms of area and we believe it will not impact cycle time. The research presented in this paper is at a first stage; nevertheless, our results for a set of numerical application show a speedup of 5% to 22%, and in any case no performance degradation was observed.