Load Value Prediction Training and Table Fusion

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Solution Overview

Problem

Processing systems face challenges in improving throughput and reducing power consumption, particularly due to load execution latency, which can account for 20% to 40% of executed instructions and leads to processor stalls and increased power usage.

Innovation Solution

The implementation of load value predictors, including last value predictors, stride address predictors, content address predictors, and content value predictors, which train to predict load values or addresses, allowing speculative execution and reducing latency through accurate predictions and recovery actions, along with smart training and table fusion optimizations to enhance predictor efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple load value predictors are trained simultaneously, then prediction accuracy improves, but power consumption increases and training efficiency decreases

Engineering Contradiction:
Improveprediction accuracyVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The system employs self-service through automatic predictor selection and training management. The load value prediction unit automatically determines which predictors to train based on prediction outcomes, and the system self-regulates training frequency and resource allocation without external intervention, optimizing power usage while maintaining accuracy

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system dynamically changes training parameters including training frequency, predictor activation states, and resource allocation based on runtime performance metrics. This allows the system to adapt power consumption levels while maintaining prediction accuracy by adjusting training intensity according to actual needs

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If load value predictors are continuously trained, then prediction accuracy improves, but processor performance decreases due to training overhead

Engineering Contradiction:
Improveprediction accuracyVSAvoidprocessor performance
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The system implements periodic action by training predictors at specific intervals rather than continuously. Training is triggered by events such as misprediction detection or after a predetermined number of predictions, allowing normal processor operations to proceed uninterrupted while still maintaining prediction accuracy through regular updates

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system performs preliminary action by pre-training predictors during idle periods or before predicted high-load scenarios. This allows the predictors to be ready with accurate models before actually needed, avoiding training overhead during critical execution paths

Inventive Principle:
Principle #10Preliminary action

3Adaptability or versatility

If predictor tables are expanded to handle more predictions, then prediction coverage improves, but hardware complexity and area increase

Engineering Contradiction:
Improveprediction coverageVSAvoidhardware complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system applies segmentation by dividing predictor tables into multiple smaller, specialized tables or partitions. Each table handles specific types of predictions or address spaces, reducing the complexity of any single table while collectively providing comprehensive coverage. This modular approach allows independent optimization of each segment

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system implements universality by designing predictor tables that can serve multiple purposes and handle diverse prediction scenarios. The same table structure and hardware resources are used across different prediction contexts, eliminating the need for separate dedicated tables for each prediction type and reducing overall hardware complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentUS11243772B2Efficient load value prediction
Publication Date: 2022.02.08 QUALCOMM INC
  • US11243772B2 patent drawing
  • US11243772B2 patent drawing
  • US11243772B2 patent drawing

AI summary

Certain aspects of the present disclosure provide techniques for training load value predictors, comprising: determining if a prediction has been made by one or more of a plurality of load value predictors; determining a misprediction has been made by one or more load value predictors of the plurality of load value predictors; training each of the one or more load value predictors that made the misprediction; and resetting a confidence value associated with each of the one or more load value predictors that made the misprediction.