A Dynamic Control Mechanism for Pipeline Stage Unification by Identifying Program Phases

Jun YAO  Shinobu MIWA  Hajime SHIMADA  Shinji TOMITA  

IEICE TRANSACTIONS on Information and Systems   Vol.E91-D   No.4   pp.1010-1022
Publication Date: 2008/04/01
Online ISSN: 1745-1361
DOI: 10.1093/ietisy/e91-d.4.1010
Print ISSN: 0916-8532
Type of Manuscript: PAPER
Category: Computer Systems
energy saving,  dynamic optimization,  pipeline stage unification,  program phase,  

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Recently, a method called pipeline stage unification (PSU) has been proposed to reduce energy consumption for mobile processors via inactivating and bypassing some of the pipeline registers and thus adopt shallow pipelines. It is designed to be an energy efficient method especially for the processors under future process technologies. In this paper, we present a mechanism for the PSU controller which can dynamically predict a suitable configuration based on the program phase detection. Our results show that the designed predictor can achieve a PSU degree prediction accuracy of 84.0%, averaged from the SPEC CPU2000 integer benchmarks. With this dynamic control mechanism, we can obtain 11.4% Energy-Delay-Product (EDP) reduction in the processor that adopts a PSU pipeline, compared to the baseline processor, even after the application of complex clock gating.