Communication Control Device for Parallel Computer Systems
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Solution Overview
Problem
In parallel computer systems, nodes with a larger hop count to the destination switch experience significantly reduced communication bandwidth, leading to delayed data arrival and bottlenecks, especially in group communication scenarios where nodes far from the destination contribute minimally to the overall bandwidth.
Innovation Solution
A communication control device with a selector that prioritizes output packets based on priority information and updates unselected packets' priority information using weighting information related to packet size, ensuring fair bandwidth distribution across nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If switches carry out arbitration such that packets from each input port are outputted equally, then the arbitration is simple and fair, but nodes with larger hop count experience greatly reduced communication bandwidth
Solution Approach 1:
The patent changes the arbitration parameter from equal packet distribution to priority-based distribution. Each packet is assigned a priority value based on its hop count, and the arbitration mechanism selects packets with higher priority values first. This parameter change resolves the contradiction by maintaining simple arbitration logic while dramatically improving communication bandwidth for distant nodes.
Solution Approach 2:
The patent implements a self-service mechanism where each packet carries its own priority information derived from its hop count. The arbitration mechanism automatically uses this embedded information to make selection decisions, eliminating the need for complex external control while ensuring fair bandwidth allocation across all nodes.
2Adaptability or versatility
If nodes with larger hop count send data through multiple switches, then group communication can be established, but data arrival is delayed due to bandwidth reduction at each hop
Solution Approach 1:
The patent applies preliminary action by pre-calculating and embedding the priority value in each packet based on its hop count before the packet enters the network. This allows downstream switches to immediately prioritize the packet without real-time calculation, reducing delay while maintaining group communication capability.
Solution Approach 2:
The patent implements feedback by using the hop count information (which reflects the packet's journey through the network) to dynamically adjust its priority. Packets that have traversed more switches receive higher priority, creating a feedback loop that compensates for the time lost during transmission and ensures timely delivery.
3Device complexity
If arbitration distributes packets equally from each input port, then the arbitration logic is simple, but the communication bandwidth for distant nodes becomes a bottleneck
Solution Approach 1:
The patent changes the arbitration parameter from equal packet distribution to priority-based distribution. Each packet is assigned a priority value based on its hop count, and the arbitration mechanism selects packets with higher priority values first. This parameter change resolves the contradiction by maintaining simple arbitration logic while dramatically improving communication bandwidth for distant nodes.
Data Source
AI summary
A communication control device includes a plurality of inputting units to which a packet is inputted a plurality of outputting units to which the packet is outputted a selector that selects an output packet to output from an identical outputting unit among a plurality of conflict packets having the identical outputting unit as a destination, the plurality of conflict packets being selected among a plurality of packets inputted to the plurality of inputting units, based on priority information set in each conflict packet and a processing unit that updates the respective priority information of unselected packets not selected as the output packet by the selector among the plurality of conflict packets based on weighting information in accordance with a packet size.