Coherent Memory Access via Multicast Mirroring
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Solution Overview
Problem
In multicomputer systems, maintaining coherent memory access across multiple, possibly heterogeneous, and distributed memory regions is inefficient and costly, especially when ensuring consistency and coherency across a large number of endpoints.
Innovation Solution
A data distribution system with a memory-management system that uses a unique multicast mechanism and host-bus adapters to provide coherent memory access by mirroring memory regions across multiple hosts, ensuring that each group member has an identical view of shared information, accessed via the same offset, without requiring additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shared memory is used to provide coherent access across multiple endpoints, then memory coherence is achieved, but system cost and inefficiency increase significantly
Solution Approach 1:
The patent divides the shared memory into multiple distributed memory regions across different hosts. Each host maintains local memory copies, and the system segments memory access into local operations (fast) and remote operations (coordinated through the data distribution system), eliminating the need for a single centralized shared memory while maintaining coherence.
Solution Approach 2:
The patent introduces a data distribution system with host-bus adapters as an intermediary layer between endpoints and memory regions. This mediator handles memory access requests, coordinates coherence across distributed memory copies, and manages the mapping between logical memory addresses and physical distributed storage, reducing the complexity of direct shared memory management.
2Adaptability or versatility
If distributed mirrored memory is used to maintain identical copies across endpoints, then memory access flexibility is improved, but maintaining consistency and coherency becomes more complex
Solution Approach 1:
The patent implements a feedback mechanism where the data distribution system tracks memory access patterns and coherence states across distributed copies. When a memory write occurs, the system provides feedback to other hosts to update their local copies, ensuring consistency without requiring complex manual coordination. The host-bus adapters monitor and report memory state changes to maintain coherency automatically.
Solution Approach 2:
The patent enables each host to self-manage its local memory copies through the data distribution system. Each host-bus adapter independently handles local memory access, coherence validation, and synchronization with other hosts, reducing the need for centralized coordination and simplifying the overall consistency management while maintaining access flexibility.
3Reliability
If semaphores and locks are used to ensure memory consistency, then system-wide memory coherency is maintained, but access efficiency and system performance decrease
Solution Approach 1:
The patent establishes memory coherence protocols and data distribution mappings in advance during system initialization. The host-bus adapters are pre-configured with memory region mappings and coherence rules, allowing them to handle access requests efficiently without requiring runtime semaphore acquisition or lock management. Coherence is maintained through pre-established communication channels and coordinated update mechanisms.
Data Source
AI summary
A data distribution system includes a data distribution module and at least two host-bus adapters coupled to the data distribution module. The data distribution system includes a memory-management system including a plurality of memory regions. The memory-management system is coherent across the plurality of memory regions and an absolute address of each of the plurality of memory regions accessed by a same offset.