Data Repacking Circuitry for All-to-All Communication Latency
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Solution Overview
Problem
Existing collective communication systems face inefficiencies in performing all-to-all operations, particularly for small data exchanges, due to high latency and message rate costs, especially as system sizes grow.
Innovation Solution
The proposed solution involves a new all-to-all algorithm that utilizes data repacking circuitry and a control tree to efficiently transpose data blocks distributed among processes, optimizing small data exchanges by defining multiple aggregation points within the network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional all-to-all communication algorithms are used, then system scalability is maintained, but latency and message rate costs increase significantly for small data exchanges
Solution Approach 1:
The patent segments the all-to-all communication operation into multiple phases using a tree-based structure. Instead of direct N-to-N communication, the system divides processes into groups and uses intermediate aggregation points to break down the communication into smaller, more manageable steps, reducing latency for small data exchanges
Solution Approach 2:
The patent introduces intermediate aggregation points (such as root processes or dedicated aggregation nodes) that act as mediators in the communication path. Data is first aggregated to these intermediate points and then distributed to destinations, reducing the message rate cost by consolidating communications through fewer intermediate hops
2Productivity
If data is exchanged directly between all process pairs, then communication completeness is ensured, but network utilization efficiency decreases
Solution Approach 1:
The patent merges multiple data transmissions through common intermediate aggregation points. Multiple source processes send data to the same aggregation point, which then consolidates and forwards to multiple destinations. This merging approach improves network utilization by reducing redundant transmissions while maintaining complete data exchange through the aggregation logic
3Adaptability or versatility
If the system supports large communicator sizes, then scalability is improved, but performance for small data exchanges deteriorates
Solution Approach 1:
The patent employs dynamic phase-based communication strategies that adapt to communicator size. The tree-based algorithm dynamically adjusts the number of aggregation levels and phase steps based on the number of processes, allowing the system to maintain optimal performance for small data exchanges while supporting large communicator sizes through scalable tree depth
Data Source
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AI summary
A method in which a plurality of process are configured to hold a block of data destined for other processes, with data repacking circuitry including receiving circuitry configured to receive at least one block of data from a source process of the plurality of processes, the repacking circuitry configured to repack received data in accordance with at least one destination process of the plurality of processes, and sending circuitry configured to send the repacked data to the at least one destination process of the plurality of processes, receiving a set of data for all-to-all data exchange, the set of data being configured as a matrix, the matrix being distributed among the plurality of processes, and transposing the data by each of the plurality of processes sending matrix data from the process to the repacking circuitry, and the repacking circuitry receiving, repacking, and sending the resulting matrix data to destination processes.