Performance Modeling of the Cluster Interconnect Clint

The cluster interconnect Clint 1 has a segregated architecture that provides two separate transmission channels: a bulk channel optimized for high-bandwidth traffic and a quick channel optimized for low-latency traffic. The channels use buffer-free switches with fixed forwarding delays. These properties simplify scheduling as well as transmission protocols. The scheduler for the bulk channel allocates transmission paths before packets are sent off. This way collisions are avoided that lead to blockages and, with it, performance loss. In contrast, a best-effort approach is taken when transmitting packets over the quick channel. Packets are sent whenever they are available. If they collide in the switch, one packet wins and the other packets lose. A simulation model has been developed to analyze the Clint architecture. The simulation results clearly show the performance advantages of the proposed architecture. The carefully scheduled bulk channel can be loaded nearly to its full capacity without exhibiting head-of-line blocking that limits many networks while the quick channel shows a dramatic reduction in latency.