Correct Wrong Path
Bhargav Reddy Godala, Sankara Prasad Ramesh, Krishnam Tibrewala,, Chrysanthos Pepi, Gino Chacon, Svilen Kanev, Gilles A. Pokam, Daniel A., Jim\'enez, Paul V. Gratz, David I. August

TL;DR
This paper introduces a new infrastructure for trace-driven simulation that accurately models wrong path execution effects in modern CPUs, significantly improving simulation fidelity for micro-architectural research.
Contribution
It develops a method to incorporate wrong path effects into trace-driven simulators and provides open traces and tools to facilitate industry-academic collaboration.
Findings
Wrong path execution impacts cache and performance significantly.
Ignoring wrong path leads to errors of up to 20.9% in simulation results.
Open traces enable more accurate and industry-relevant simulation studies.
Abstract
Modern OOO CPUs have very deep pipelines with large branch misprediction recovery penalties. Speculatively executed instructions on the wrong path can significantly change cache state, depending on speculation levels. Architects often employ trace-driven simulation models in the design exploration stage, which sacrifice precision for speed. Trace-driven simulators are orders of magnitude faster than execution-driven models, reducing the often hundreds of thousands of simulation hours needed to explore new micro-architectural ideas. Despite this strong benefit of trace-driven simulation, these often fail to adequately model the consequences of wrong path because obtaining them is nontrivial. Prior works consider either a positive or negative impact of wrong path but not both. Here, we examine wrong path execution in simulation results and design a set of infrastructure for enabling…
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Taxonomy
TopicsParallel Computing and Optimization Techniques · Advanced Data Storage Technologies · Cloud Computing and Resource Management
