Cache-based solutions to hotspot contention in shared memory multiprocessors

A new cache-based approach for solving the tree saturation problem in multistage interconnection networks (MINs) is proposed. The scheme moves the hotspot from the main memory and distributes it in the MIN as cached copies. A stage of the MIN may have a cache copy of the hotspot and only hot requests can be routed to the cache. Due to the alternate paths taken by the hot requests the congestion at the buffers in the switches is reduced, and performance is drastically improved. Different ideas/arrangements have been tried, and it is shown that, when the proposed technique is used along with pairwise combining, all variants of the scheme perform better than pairwise combining alone even in large networks. It is concluded that utilizing only one cache (with one location) can drastically reduce the contention problem, even if pairwise combining is not implemented. Network delays are among the lowest delays reported to date