Eugene, All my remarks are related to the receive side. I think the send side optimizations are fine, but don't take my word for it.
Eugene Loh wrote: > To recap: > 1) The work is already done. How do you do "directed polling" with ANY_TAG ? How do you ensure you check all incoming queues from time to time to prevent flow control (specially if the queues are small for scaling) ? What about the one-sided that Brian mentioned where there is no corresponding receive to tell you which queue to poll ? If you want to handle all the constraints, a single-queue model is much less work in the end, IMHO. > 2) The single-queue model addresses only one of the RFC's issues. The single-queue model addresses not only the latency overhead when scaling, but also the exploding memory footprint. In many ways, these problems are the same that plagued the RDMA QP model, and the only solution was using shared receive queues. By experience, the linear overhead of polling N queues very quickly become greater than all the optimizations you can do on the send side. > 3) I'm a fan of the single-queue model, but it's just a separate discussion. No problem. You are the one doing the real work here, the rest is armchair quarterbacking :-) Patrick
