On May 8, 2015, at 8:32 PM, Doug Ledford <dledford@xxxxxxxxxx> wrote: > On Tue, 2015-05-05 at 20:22 +0000, Dave Goodell (dgoodell) wrote: >> >> In the case that usNIC is operating in UDP mode (which is the >> overwhelming majority of the cases), there is absolutely no additional >> protocol that ends up on the wire or headers in the user buffers >> besides UDP/IP/Ethernet. They are 100% plain UDP packets, they just >> happen to be sent via OS-bypass queues instead of traveling through the >> kernel networking stack. >> >> [^^^^^ there continues to be confusion about this for some reason, but >> I don't know why] > > I really need to just sit down and read your driver front to back. Feel free to ping me off-list if you want any explanation about what's going on in the usnic_verbs module. I'm happy to help. > The > confusion probably comes from people (such as myself) that first think > about this and go "Well, if you have multiple queue pairs, and UDP, then > you need a header to tell what QP a packet goes to" (which assumes a > RoCE like usage of UDP where all packets go to the same UDP address) > where your actual usage is probably more iWARP like in that the IP/UDP > SRC/DST combo maps to a specific QP, right? I don't know much about the details of iWARP, but yes, a UDP/IP src/dst port combo maps to a specific QP when using USNIC_UDP QPs. We do _not_ use a single well-known port. -Dave -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
