Hiding the Misprediction Penalty of a Resource—Efficient High—Performance Processor

Amit Golander, Shlomo Weiss

Research output: Contribution to journalArticlepeer-review

Abstract

Misprediction is a major obstacle for increasing speculative out-of-order processors performance. Performance degradation depends on both the number of misprediction events and the recovery time associated with each one of them. In recent years a few checkpoint based microarchitectures have been proposed. In comparison with ROB-based processors, checkpoint processors are scalable and highly resource efficient. Unfortunately, in these proposals the misprediction recovery time is proportional to the instruction queue size. In this paper we analyze methods to reduce the misprediction recovery time. We propose a new register file management scheme and techniques to selectively flush the instruction queue and the load store queue, and to isolate deeply pipelined execution units. The result is a novel checkpoint processor with Constant misprediction RollBack time (CRB). We further present a streamlined, cost-efficient solution, which saves complexity at the price of slightly lower performance.

Original languageEnglish
Pages (from-to)1-32
Number of pages32
JournalTransactions on Architecture and Code Optimization
Volume4
Issue number4
DOIs
StatePublished - 2008

Keywords

  • Checkpoints
  • Design
  • Misprediction
  • Out-Of-Order Execution
  • Performance
  • Rollback
  • Scalable Architecture

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