Remote Memory Barrier Tracking With Speculative Acknowledgements

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Solution Overview

Problem

The increasing complexity and latency in synchronizing memory operations across multiple processing units and memory systems in complex processors, particularly GPUs, result in reduced memory performance due to the overhead of memory synchronization operations.

Innovation Solution

Implementing speculative remote memory operation tracking using a centralized or distributed acknowledgement tracking engine to coalesce acknowledgements, allowing memory synchronization operations to be performed in the background, thereby reducing latency and bandwidth requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If memory synchronization operations are performed across all processing units and memory systems, then synchronization reliability is improved, but latency increases

Engineering Contradiction:

Improvesynchronization reliabilityVSAvoidlatency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs speculative remote memory operation tracking in advance by issuing read operations before the actual memory synchronization is needed. The acknowledgement tracking engine monitors these speculative operations and prepares acknowledgements beforehand, so that when the actual synchronization point is reached, the system can quickly determine if synchronization is complete without waiting for all remote operations to fully complete.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an acknowledgement tracking engine as an intermediary component that decouples the memory synchronization operation from the actual remote memory operations. This engine tracks speculative read operations and generates acknowledgements that indicate whether synchronization is complete, without requiring direct coordination between all processing units and memory systems.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the number of processing units and memory systems increases, then processing capacity is improved, but device complexity increases

Engineering Contradiction:

Improveprocessing capacityVSAvoidsynchronization complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent extracts the synchronization tracking functionality from the individual processing units and memory systems and consolidates it into a dedicated acknowledgement tracking engine. This separation allows the processing units and memory systems to operate independently with higher capacity while the tracking engine handles the complexity of coordinating among them.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The acknowledgement tracking engine serves multiple functions: it tracks speculative remote memory operations, determines synchronization completion, and provides acknowledgements to multiple processing units. This multi-functional component handles the coordination complexity centrally, allowing the system to scale without proportionally increasing synchronization complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If memory synchronization operations are performed across all components, then synchronization completeness is improved, but bandwidth requirements increase

Engineering Contradiction:

Improvesynchronization completenessVSAvoidbandwidth requirements

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The system performs partial synchronization tracking by monitoring only the speculative read operations that are likely to affect synchronization, rather than tracking all memory operations. The acknowledgement tracking engine issues read operations speculatively and tracks only those that require acknowledgment, reducing the overall bandwidth requirements while maintaining synchronization completeness.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS12487746B2Speculative remote memory operation tracking for efficient memory barrier

Publication Date: 2025.12.02 NVIDIA CORP

AI summary

Various embodiments include techniques for performing speculative remote memory operation tracking in a multiprocessor computing system. Conventionally, transfers of data between processors and other components of a computing system require memory synchronization operations to determine that the data is valid and coherent before the data is transferred from a destination to a requesting source. Existing techniques for performing these memory synchronization operations are increasingly inefficient as the number of components in a computing system increases, particularly for remote memory operations. The disclosed techniques track remote memory operations and speculatively perform these memory synchronization operations. As a result, a given memory synchronization operation is often complete prior to the corresponding remote memory operation arrives at the destination, leading to improved efficiency and performance of remote memory operations in complex computing systems.