Efficient Agent-Based Multicast on Wormhole Switch-Based Irregular Networks

這一篇論文主要是在wormehole switch-based network中提出一個有效的代理人演算法。在不規則網路中，一個叢集往往需要一個代理人來統籌集體通訊的排程。 代理人與代理人及非代理人之間的通訊排程極其複雜，因此我們提出一個排程的最佳化演算法，以提升集體通訊的效率。 我們最後與一個有效的排程方法SPCCO來做比較。在訊息量高時，我們所得到的效能比SPCCO來得好。This paper describes an agent-based approach for scheduling multiple multicast on wormhole switch-based networks with irregular topologies. Multicast/broadcast is an important communication pattern, with applications in collective communication operations such as barrier synchronization and global combining. Our approach assigns an agent to each subtree of switches such that the agents can exchange information e ciently and independently. The entire multicast problem is then recursively solved with each agent sending message to those switches that it is responsible for. In this way, communication is localized by the assignment of agents to subtrees. This idea can be easily generalized to multiple multicast since the order of message passing among agents can be interleaved for di erent multicasts. The key to the performance of this agent-based approach is the message-passing scheduling between agents and the destination processors. We propose an optimal scheduling algorithm to solve this problem. We conduct extensive experiments to demonstrate the e ciency of our approach by comparing our results with SPCCO, a highly e cient multicast algorithm reported in literature. We found that SPCCO su ers link contention when the number of simultaneous multiple multicast becomes large. On the other hand, our agent-based approach achieves better performance in large cases.1 Introduction 3 2 Model 6 2.1 Routing Mechanism 6 2.2 Contention 7 3 Agent-Based Algorithms 8 3.1 Single Multicast 8 4 Multiple Multicast 10 5 Message Forward Model 11 6 Forwarding Algorithm 14 6.1 Criticality 14 6.2 The Testing Algorithm 14 6.3 Optimal Schedule 18 7 Simulation Experiments and Results 19 8 Conclusion 2

Efficient Agent-based Multicast on Wormhole Switch-based Irregular Networks

... scheduling multiple multicast on wormhole switch-based networks. Multicast/broadcast is an important communication pattern, with applications in collective communication operations such as barrier synchronization and global combining. Our approach assigns an agent to each subtree of switches such that the agents can exchange information efficiently and independently. The entire multicast problem is then recursively solved with each agent sending message to those switches that it is responsible for. In this way, communication is localized by the assignment of agents to subtrees. This idea can be easily generalized to multiple multicast since the order of message passing among agents can be interleaved for different multicasts. We conduct experiments to demonstrate the efficiency of our approach by comparing the results with SPCCO, a highly efficient multicast algorithm. We found that SPCCO suffers link contention when the number of simultaneous multiple multicast becomes large. On the other hand, our agent-based approach achieves better performance in large cases