Wafer-Scale Deep Learning Accelerator Redundancy

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Solution Overview

Problem

Current deep learning technologies face challenges in achieving improvements in accuracy, performance, and energy efficiency, particularly in the areas of cost, profitability, and utility within the field of accelerated deep learning.

Innovation Solution

The implementation of a deep learning accelerator via wafer-scale integration, utilizing redundancy-enabling couplings between processing elements, and incorporating floating-point units with programmable exponent bias and stochastic rounding capabilities, along with advanced data structure descriptors and wavelet-based computations, enables efficient neural network training and inference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If wafer-scale integration is used to implement deep learning accelerator, then productivity and energy efficiency are improved, but device complexity and manufacturing precision requirements increase

Engineering Contradiction:
Improvedeep learning processing throughputVSAvoidwafer-scale integration complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The wafer is divided into multiple reticles, each containing an array of processing elements (PEs) arranged in a grid. Each reticle can be independently manufactured and tested, then integrated into the complete wafer-scale system. This segmentation allows manageable complexity while achieving high overall productivity through parallel processing across all PEs.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system uses configurable parameters including programmable exponent bias in floating-point units and adjustable rounding modes to optimize processing accuracy and energy efficiency. These parameter changes allow the same hardware architecture to adapt to different deep learning workloads and precision requirements.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If redundancy-enabling couplings are implemented between processing elements, then reliability is improved through defect replacement, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improveprocessing element functionalityVSAvoidcoupling configuration complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Redundancy-enabling couplings are pre-configured between processing elements during wafer fabrication, before any defects are known. This preliminary setup allows rapid defect mapping and replacement during testing without requiring complex reconfiguration logic. The couplings are designed to be activated only when defects are identified, simplifying the overall control architecture.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system creates logical copies of processing elements through redundancy-enabling couplings, where functional PEs can replace defective ones. This copying approach maintains system reliability without duplicating the entire wafer, as only specific PE instances are replicated based on defect locations identified during testing.

Inventive Principle:
Principle #26Copying

3Manufacturing precision

If floating-point units with programmable exponent bias and stochastic rounding are used, then manufacturing precision and accuracy are improved, but device complexity and energy consumption increase

Engineering Contradiction:
Improvefloating-point computation accuracyVSAvoidfloating-point unit energy consumption
Core Design Contradiction:
Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The floating-point units incorporate programmable exponent bias and configurable rounding modes that can be dynamically adjusted based on the specific deep learning workload and precision requirements. This dynamic configurability allows the system to optimize the balance between accuracy and energy consumption, using higher precision modes only when necessary for critical computations.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes numerical parameters including exponent bias values and rounding behavior to match the requirements of different neural network layers and operations. By adapting these parameters rather than using fixed high-precision arithmetic everywhere, the system reduces overall energy consumption while maintaining necessary accuracy.

Inventive Principle:
Principle #35Parameter changes

4Productivity

If advanced data structure descriptors and wavelet-based computations are implemented, then productivity and accuracy are improved, but device complexity increases

Engineering Contradiction:
Improveneural network training and inference speedVSAvoiddata structure processing complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

Data structures are divided into descriptors that capture essential properties and wavelet-based representations that decompose complex data into manageable frequency components. This segmentation allows the processing elements to handle simplified data representations efficiently, improving productivity without requiring full complexity processing for every operation.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentUS11328208B2Processor element redundancy for accelerated deep learning
Publication Date: 2022.05.10 CEREBRAS SYSTEMS INC
  • US11328208B2 patent drawing
  • US11328208B2 patent drawing
  • US11328208B2 patent drawing

AI summary

Techniques in advanced deep learning provide improvements in one or more of cost, accuracy, performance, and energy efficiency. The deep learning accelerator is implemented at least in part via wafer-scale integration. The wafer comprises a plurality of processor elements, each augmented with redundancy-enabling couplings. The redundancy-enabling couplings enable using redundant ones of the processor elements to replace defective ones of the processor elements. Defect information gathered at wafer test and/or in-situ, such as in a datacenter, is used to determine configuration information for the redundancy-enabling couplings.