Issue mechanism for embedded simultaneous multithreading processor

Chengjie Zang*, Shigeki Imai, Steven Frank, Shinji Kimura


研究成果: Article査読

3 被引用数 (Scopus)


Simultaneous Multithreading (SMT) technology enhances instruction throughput by issuing multiple instructions from multiple threads within one clock cycle. For in-order pipeline to each thread, SMT processors can providelarge number of issued instructions close to or surpass than using out-of-order pipeline. In this work, we show an efficient issue logic for predicated instruction sequence with the parallel flag in each instruction, where the predicate register based issue control is adopted and the continuous instructions with the parallel flag of '0' are executed in parallel. The flag is pre-defined by a compiler. Instructions from different threads are issuedbased on the round-robin order. We also introduce an Instruction Queue skipmechanism for thread if the queue is empty. Using this kind of issue logic,we designed a 6 threads, 7-stage, in-order pipeline processor. Based on this processor, we compare round-robin issue policy (RR(T1-Tn)) with other policies: thread one always has the highest priority (PR(T1)) and thread one or thread n has the highest priority in turn (PR(T1-T n)). The results show that RR(T1-Tn) policy outperforms others and PR(T1-Tn) is almost the same to RR(T1-Tn) from the point of view of the issued instructions per cycle.

ジャーナルIEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences
出版ステータスPublished - 2008

ASJC Scopus subject areas

  • 信号処理
  • コンピュータ グラフィックスおよびコンピュータ支援設計
  • 電子工学および電気工学
  • 応用数学


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