Extending Correlation in Branch Prediction Schemes
نویسندگان
چکیده
The main aim of this research is to propose a new Two-Level Adaptive Branch Prediction scheme, based on additional correlation information. Conventional two-level adaptive branch prediction exploits the correlation between the outcome of a branch and the path followed through a program to reach the branch. Typically the program path is identified by recording whether each branch on the path is taken or not taken. Unfortunately, this limited information is insufficient to allow one path to a branch to be distinguished from other potential paths to the same branch. In this paper, we explore the benefits of adding sufficient information, in the form of successive branch addresses, to uniquely identify each program path. We use trace-driven simulation to compare our modified branch prediction scheme with a conventional GAp two-level predictor and demonstrate that our new predictor performs better than the conventional GAp scheme at the same level of hardware complexity.
منابع مشابه
The Performance of Counter- and Correlation-Based Schemes for Branch Target Buffers
Branch turget buffers, or BTBs, can be used to improve CPU performance by maintaining target and history information of previously executed branches. We present tracedriven simulation results comparing counter-based and correlation-based prediction schemes for a variety of branch target buffer sizes. We report relative performance estimates to show both the relative merits of various techniques...
متن کاملExtending the Cell SPE with Energy Efficient Branch Prediction
Energy-efficient dynamic branch predictors are proposed for the Cell SPE, which normally depends on compiler-inserted hint instructions to predict branches. All designed schemes use a Branch Target Buffer (BTB) to store the branch target address and the prediction, which is computed using a bimodal counter. One prediction scheme predecodes instructions when they are fetched from the local store...
متن کاملCompiler - Assisted Value Correlation for Indirect Branch Prediction ∗
Indirect branch prediction is important to boost instruction-level parallelism in modern processors. Previous indirect branch predictions usually cannot achieve high performance for the ineffectiveness of correlated information. This paper proposes the Compilerassisted value correlation (CVC), a hardware/software cooperative indirect branch prediction scheme. The key is to identify effective va...
متن کاملDesign and Performance Evaluation of Global History Dynamic Branch Predictors
The importance of accurate branch prediction to future processors has been widely recognized. The correct prediction of conditional branch outcomes can help avoid pipeline bubbles and attendant loss in performance. In order to achieve high prediction accuracy, numerous dynamic branch prediction schemes that exploit branch correlation have recently been proposed. Several of the best predictors a...
متن کاملChip Designers to Consider before Using Any of the Branch Prediction Schemes. 6.0 Conclusions
After we reviewed our simulation results, we realize that the way we set the combined DHT/BHT table size may not have been the optimal. For simplicity, we assumed that the DHT and BHT components had the same number of table entries. We now feel that a the DHT should have more table entries than the BHT. We believe that the prediction rates will remain lower than the DHT-2 alone. The main advant...
متن کامل