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llcoolj

is the storage for having virtual channels significant?

gogogo

how do virtual channels interact with the physical channels to prevent deadlocks?

bpr

@gogogo, without virtual channels, each physical channel is a single, dedicated link. If a packet flow is using the link, then no other flow can use it and is blocked. Since there are only single buffers in each router, if a flow blocks, then its packets are blocked in multiple routers and the physical channels between those routers remain dedicated to the blocked flow. Each cycle, the routers will attempt to send the next packet, but fail.

By adding virtual channels, the router will now multiplex the virtual channels over the single physical channel. So even if one flow blocks, other flows may still make progress on their virtual channels.

gogogo

how does the router actually achieve this though? like is there some sort of "mapping" between components of the virtual channels and portions of the physical channel, if this makes any sense?

LazyKiller

In this case, is there still only one flow that can be transmitting?