Speculative sequential consistency with little custom storage

C. Gniady, B. Falsafi

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


This paper proposes SC++lite, a sequentially consistent system that relaxes memory order speculatively to bridge the performance gap among memory consistency models. Prior proposals to speculatively relax memory order require large custom on-chip storage to maintain a history of speculative processor and memory state while memory order is relaxed. SC++lite uses the memory hierarchy to store the speculative history, providing a scalable path for speculative SC systems across a wide range of applications and system latencies. We use cycle-accurate simulation of shared-memory multiprocessors to show that SC++lite can fully relax memory order while virtually obviating the need for custom on-chip storage. Moreover while demand for storage increases significantly with larger memory latencies, SC++lite's ability to relax memory order remains insensitive to memory latency. An SC++lite system can improve performance over a base SC system by 28% with only 2 KB of custom storage in a system with 16 processors. In contrast, speculative SC systems with custom storage require 51 KB of storage to improve performance by 31% over a base SC system.

Original languageEnglish (US)
Article number1106016
Pages (from-to)179-188
Number of pages10
JournalParallel Architectures and Compilation Techniques - Conference Proceedings, PACT
StatePublished - 2002


  • Bridges
  • Computer architecture
  • Delay
  • Hardware
  • History
  • Laboratories
  • Microprocessors
  • Proposals
  • System-on-a-chip

ASJC Scopus subject areas

  • Software
  • Theoretical Computer Science
  • Hardware and Architecture


Dive into the research topics of 'Speculative sequential consistency with little custom storage'. Together they form a unique fingerprint.

Cite this