An effective synchronization network for large multiprocessor systems

The authors propose a single-stage combining network to handle synchronization traffic, which is separated from the regular memory traffic. A single-stage combining network has several advantages: (1) It is very cost effective because only one stage is needed (instead of logN stages). (2) Only one network is needed to handle both forward and returning requests. (3) All synchronization traffic is confined to a single stage; hence, packets have more opportunities to combine. (4) Combined requests are distributed evenly through the network; the wait buffer size is reduced. (5) Fast-finishing algorithms can be used to shorten the network delay. Because of all these advantages, the authors show that a single-stage combining network gives good performance at a lower cost than a multistage combining network