Infiniband has unreliable transports (UC and UD) which do not use hardware ACKs. Does this mean that they actually suffer from packet loss? If so, in what context is Infiniband a lossless medium?
My experience suggests that even unreliable transports do *not* witness packet loss. I have 20 client machines bombarding one server machine with RDMA writes over UC, and all the (billions) operations complete successfully. Further, each clients gets throttled when more client machines are added - suggesting some flow control. So, does this mean that flow control kicks in even in unreliable transports, i.e., is Infiniband's hardware level flow control decoupled from its ACK mechanism? I only have access to a small cluster -- will I see packet loss in larger clusters? Or is the "unreliability" of UC and UD restricted to packet reordering only? Thanks for your help! --Anuj Kalia -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
