Improving Power Saving for Filter-Based Branch Target Buffer

摘要

In this paper we propose an improved sentry-table (S-Table) filter based low power branch target buffer (BTB) of branch predictor in modern processors. The S-Table scheme filters unnecessary accesses of BTB to reduce dynamic power dissipation, but previously the power saving was found bound by the decoder power. The proposed hierarchical decoder (H-DEC) can significantly offset such effect. CACTI, SimpleScalar, Wattch tools and SPEC2000 benchmarks were used to conduct the investigation. From our empirical studies, power savings for BTB can be further improved from 19～38% to 68～91%; and those for branch predictor from 17～21% to 37～81%.