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mak

"Flits become minimum granularity of routing/buffering" Isn't the case that unit of routing is still packet, not flit?

firebb

What is the difference between Wormhole flow control and cut through flow control? They seems to behave in the same way.

mak

One major difference is the amount of buffering you need at each switch for per packet. In case of wormhole flow control, switch needs to buffer only a single flit. This is because, in case of wormhole flow control, if head flit blocks, there will be no further transmission of flits for that particular packet from any other nodes. However, in case of cut-through, in worst case, each switch might need to buffer complete packet if its outgoing link is blocked, because the previous node will keep sending the rest of the packet, irrespective of the status of outgoing links at subsequent switches.