The Synchronization Power of Coalesced Memory Accesses

  • Authors:

  • Phuong Hoai Ha;Philippas Tsigas;Otto J. Anshus

  • Affiliations:

  • Department of Computer Science, Faculty of Science, University of Tromsø, Tromsø, Norway NO-9037;Department of Computer Science and Engineering, Chalmers University of Technology, Göteborg, Sweden SE-412 96;Department of Computer Science, Faculty of Science, University of Tromsø, Tromsø, Norway NO-9037

  • Venue:
  • DISC '08 Proceedings of the 22nd international symposium on Distributed Computing
  • Year:
  • 2008

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Abstract

Multicore processor architectures have established themselves as the new generation of processor architectures. As part of the one core to many cores evolution, memory access mechanisms have advanced rapidly. Several new memory access mechanisms have been implemented in many modern commodity multicore processors. Memory access mechanisms, by devising how processing cores access the shared memory, directly influence the synchronization capabilities of the multicore processors. Therefore, it is crucial to investigate the synchronization power of these new memory access mechanisms.This paper investigates the synchronization power of coalesced memory accesses, a family of memory access mechanisms introduced in recent large multicore architectures like the CUDA graphics processors. We first design three memory access models to capture the fundamental features of the new memory access mechanisms. Subsequently, we prove the exact synchronization power of these models in terms of their consensus numbers. These tight results show that the coalesced memory access mechanisms can facilitate strong synchronization between the threads of multicore processors, without the need of synchronization primitives other than reads and writes. In the case of the contemporary CUDA processors, our results imply that the coalesced memory access mechanisms have consensus numbers up to sixteen.