Hazard Prediction Buffer for Memory Access Groups
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Solution Overview
Problem
Conventional processor systems face challenges in accurately predicting and managing instruction pipeline hazards and memory ordering violations during out-of-order execution, leading to inefficiencies and potential data inconsistencies.
Innovation Solution
A system that utilizes a buffer associated with branch prediction to store hazard prediction entries for groups of memory access instructions, allowing for the prediction of instruction pipeline hazards and executing memory access instructions based on these predictions, thereby minimizing hazards and reducing prediction costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If out-of-order execution is implemented to increase throughput, then processor productivity is improved, but instruction pipeline hazards and memory order violations occur
Solution Approach 1:
The patent applies preliminary action by predicting hazards before they occur in the instruction pipeline. A hazard prediction buffer stores prediction entries that are checked before executing memory access instructions out-of-order, allowing the processor to proactively identify and handle potential hazards rather than reacting after they occur. This enables out-of-order execution to proceed safely by having hazard detection mechanisms already in place.
Solution Approach 2:
The hazard prediction buffer serves as an intermediary between the out-of-order execution mechanism and the hazard detection/correction system. Instead of directly monitoring all out-of-order memory operations, the buffer acts as a middle layer that pre-evaluates instructions and provides hazard information to the execution pipeline, simplifying the overall hazard management while maintaining reliability.
2Measurement precision
If hazard prediction is performed for each memory access instruction, then prediction accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges hazard prediction functionality into the existing branch prediction buffer infrastructure. Instead of creating a separate complex hazard prediction mechanism for each memory instruction, the system combines hazard prediction with the branch prediction buffer that already exists in modern processors. This sharing of hardware resources reduces overall device complexity while maintaining prediction accuracy through the unified buffer structure.
Solution Approach 2:
The hazard prediction buffer is designed to handle groups of memory access instructions simultaneously rather than individual instructions. By predicting hazards for entire groups of instructions at once, the buffer achieves comprehensive coverage and high prediction accuracy while using a single multi-functional data structure that serves multiple prediction purposes, thereby reducing the need for multiple separate prediction mechanisms.
Data Source
AI summary
Various aspects provide for facilitating prediction of instruction pipeline hazards in a processor system. A system comprises a fetch component and an execution component. The fetch component is configured for storing a hazard prediction associated with a group of memory access instructions in a buffer associated with branch prediction. The execution component is configured for executing a memory access instruction associated with the group of memory access instructions as a function of the hazard prediction entry. In an aspect, the hazard prediction entry is configured for predicting whether the group of memory access instructions is associated with an instruction pipeline hazard.