In a large-scale multiprocessing system, contention for a particular m
emory location (called hotspot), may create congestion in the intercon
nection network. Usually a tree of saturated buffers rooted at the hot
memory module and extending to the processors is formed which causes
excessive delay for both hotspot and regular nonhotspot requests. To p
revent tree saturation, a simple combining technique is proposed. The
technique attempts to increase the chances of request combining. The n
ew scheme called input queue combining uses simpler queueing structure
compared to those proposed for conventional pairwise combining. The c
omponent count in each queue reduces to one-third of that in pairwise
combining and the number for the waitbuffer reduces to half. While con
ventional pairwise combining is effective only for smaller networks, t
he proposed technique eliminates tree saturation even in very large ne
tworks, with reasonable delay. Networks delays reported here are among
the lowest reported to date.