Area-Aware pipeline gating for embedded processors

• Authors: Babak Salamat;Amirali Baniasadi
• Venue: PATMOS'05 Proceedings of the 15th international conference on Integrated Circuit and System Design: power and Timing Modeling, Optimization and Simulation
• Year: 2005

Modern embedded processors use small and simple branch predictors to improve performance. Using complex and accurate branch predictors, while desirable, is not possible as such predictors impose high power and area overhead which is not affordable in an embedded processor. As a result, for some applications, misprediction rate can be high. Such mispredictions result in energy wasted down the mispredicted path. We introduce area-aware and low-complexity pipeline gating mechanisms to reduce energy lost to possible branch mispredictions in embedded processors. We show that by using a simple gating mechanism which comes with 33-bit area overhead, on average, we can reduce the number of executed instructions by 17% (max: 30%) while paying a negligible performance cost (average 1.1%).