Branch Prediction Migration for Multi-Core Architectures

Abstract

Thread migration is ubiquitous in multi-core architectures. When a thread migrates to a new core, the branch information of the branch predictor on new core is absent, which will lead to the predictor won't work as intended until the warm-up finish. In this poster, we point out that, when a thread migrates to a new core, the warm-up time of branch predictors can be reduced by migrating branch history information from the source core to the target. In addition, we improve branch prediction accuracy by migrating branch history information including prediction tables and GHR. Moreover, several migration strategies are introduced to fully exploit the performance of branch predictor migration. Preliminary performance results shows that, compared to the experiment baseline which dosen't migrate any branch history information, branch prediction migration reduces MPKI of the branch predictor on new core by 43.46% on average.