Separated High-bandwidth and Low-latency Communication in the Cluster Interconnect Clint
Separated High-bandwidth and Low-latency Communication in the Cluster Interconnect Clint
01 October 2002
An interconnect for a high-performance cluster has to be optimized in respect to both high throughput and low latency. To avoid the tradeoff between throughput and latency, the cluster interconnect Clint has a segregated architecture that provides two physically separate transmission channels: a bulk channel optimized for high-bandwidth traffic and a quick channel optimized for low-latency traffic. Different scheduling strategies are applied. The bulk channel uses a scheduler that globally allocates time slots on the transmission paths before packets are sent off. In this way, collisions as well as blockages are avoided. In contrast, the quick channel takes a best-effort approach by sending packets whenever they are available thereby risking collisions and retransmissions.
Clint is targeted specifically at small- to medium-sized clusters offering a low-cost alternative to symmetric multiprocessor (SMP) systems. This design point allows for a simple and cost-effective implementation. In particular, by buffering packets only on the hosts and not requiring any buffer memory on the switches, protocols are simplified as switch forwarding delays are fixed, and throughput is optimized as the use of a global schedule is now possible.
This report is an extended version of a paper presented at SC2002, Baltimore, Maryland, November 2002.
Venue : N/A
File Name : smli_tr-2002-115.pdf