Parallel Computer Arbitration for Balanced Data Transfer
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Solution Overview
Problem
In parallel computer systems, data transfer becomes unbalanced due to differences in communication probability between computation nodes and ports, leading to inefficient communication, as high-probability combinations are favored, resulting in exclusive bus usage and reduced efficiency.
Innovation Solution
A parallel computer system with a data transfer device that includes an arbitration unit for selecting computation nodes, a data transfer unit for transferring data, and a combination determining unit that dynamically pairs computation nodes with ports based on access counts, ensuring balanced communication by setting master ports dynamically and canceling unbalanced access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data transmission is performed by connecting computation nodes and ports at the same degree in the conventional system, then the system structure is simple, but it becomes difficult to improve efficiency of data transfer processing since input ports having high communication probability and low communication probability are on a par with each other
Solution Approach 1:
The patent implements dynamic arbitration where the selection of computation nodes for data transmission is adjusted in real-time based on communication probability. The arbitration unit changes its behavior from static equal treatment to dynamic preferential treatment, selecting nodes with higher communication probability more frequently to improve overall data transfer efficiency.
Solution Approach 2:
The system changes the arbitration parameter from uniform selection probability to probability-based selection. By modifying the selection criterion to consider communication probability as a weighting factor, the system optimizes data transfer efficiency without fundamentally changing the crossbar switch architecture.
2Productivity
If a combination of computation nodes and ports having high communication probability is preferentially connected as a group, then data transfer efficiency can be improved, but it causes unbalanced data transfer and exclusive bus usage reducing overall system efficiency
Solution Approach 1:
The patent employs feedback mechanisms where the arbitration unit continuously monitors communication probability and adjusts node selection accordingly. This feedback loop prevents any single node- port combination from monopolizing the bus by dynamically adapting selection based on current system state, thereby maintaining balanced data transfer across all ports.
Solution Approach 2:
The system dynamically adjusts the pairing of computation nodes with ports based on real-time communication probability rather than maintaining fixed preferential connections. This dynamic reconfiguration prevents exclusive bus usage by any single combination while still prioritizing high-probability communications when appropriate.
3Speed
If arbitration requests are deleted after one port selection to reduce processing overhead, then processing speed improves, but it creates imbalance in communication opportunities across different ports
Solution Approach 1:
The patent modifies the arbitration request handling parameter by introducing probability-weighted selection instead of simple deletion. Requests are not immediately discarded but are reconsidered in subsequent arbitration cycles with probability-based weighting, ensuring both fast processing and fair communication opportunities across all ports.
Data Source
AI summary
A switch includes a plurality of ports and a combination determining unit that determines a central processing unit (CPU) to be paired with one of the ports. The port includes: an arbitration circuit that selects the CPU to be paired therewith when receiving an arbitration request from the CPU to be paired in a predetermined state, and selects one of the CPUs from which the arbitration request has been received in other cases to return transmission permission; and a data transfer unit that transfers the received data from the selected CPU to another CPU. The CPU includes: a request transmission unit that transmits the arbitration request to the ports; and a data transmission unit that transmits data to the paired port when the arbitration request is transmitted to the paired port in the predetermined state, and transmits data to the ports that have returned transmission permission in other cases.