Stacked Processor-DRAM Ring Topology for Parallel ML Training

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Solution Overview

Problem

Current stacked device systems face limitations in efficiently interconnecting multiple processing units and memory devices for parallel machine learning tasks, particularly in implementing distributed and parallel algorithms like Ring-AllReduce, due to constraints in data and control signal communication through shared through-silicon via connections.

Innovation Solution

The system employs a ring topology interconnection configuration using through-silicon via (TSV) connections between DRAM and processor dies, enabling efficient data and control signal communication through a handshake protocol, allowing multiple device stacks to operate in parallel on different neural network models or compute problems by configuring separate ring topologies and using interconnect selectors to include or exclude the host.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple device stacks are interconnected using shared through-silicon via connections, then data and control signal communication is enabled, but communication efficiency and scalability are limited

Engineering Contradiction:
Improvecommunication efficiencyVSAvoidinterconnection complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The system segments the interconnection architecture into multiple independent ring topologies, where each ring can operate separately. This allows different device stacks to be organized into distinct communication groups, enabling parallel operations without interference. The segmentation of shared TSV connections into dedicated ring paths resolves the bottleneck of shared bandwidth while maintaining scalability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from traditional two-dimensional planar interconnections to three-dimensional stacked architectures with vertical TSV connections. By adding the vertical dimension, the system achieves higher density and enables multiple rings to operate simultaneously at different vertical levels, dramatically improving communication efficiency without increasing lateral complexity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If device stacks operate in parallel on different neural network models, then processing efficiency improves, but coordination and data transfer between stacks become more complex

Engineering Contradiction:
Improveprocessing efficiencyVSAvoidcoordination complexity
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The host device serves as an intermediary that coordinates operations across multiple device stacks. It manages the distribution of neural network models, collects results, and orchestrates the parallel training processes. This centralized coordination simplifies the complexity of inter-stack communication while maintaining high processing efficiency through parallel operations.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system performs preliminary actions by pre-configuring ring topologies and pre-distributing neural network models to appropriate device stacks before parallel processing begins. This preparation phase establishes the communication pathways and data distribution patterns needed for efficient parallel execution, reducing coordination overhead during actual processing.

Inventive Principle:
Principle #10Preliminary action

3Adaptability or versatility

If separate ring topologies are configured for different compute problems, then parallel processing capability increases, but system configuration complexity increases

Engineering Contradiction:
Improveparallel processing capabilityVSAvoidconfiguration complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The ring topology configuration is made dynamic and reconfigurable, allowing the system to adapt its interconnection patterns based on the specific compute problems being solved. Interconnect selectors enable runtime reconfiguration of ring topologies, so the system can optimize its architecture for different workloads without permanent hardware changes, balancing versatility with manageable complexity.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS11755523B2Stacked device system
Publication Date: 2023.09.12 RAMBUS INC
  • US11755523B2 patent drawing
  • US11755523B2 patent drawing
  • US11755523B2 patent drawing

AI summary

Multiple device stacks are interconnected in a ring topology. The inter-device stack communication may utilize a handshake protocol. This ring topology may include the host so that the host may initialize and load the device stacks with data and/or commands (e.g., software, algorithms, etc.). The inter-device stack interconnections may also be configured to include/remove the host and/or to implement varying numbers of separate ring topologies. By configuring the system with more than one ring topology, and assigning different problems to different rings, multiple, possibly unrelated, machine learning tasks may be performed in parallel by the device stack system.