On Sun, Aug 25, 2013 at 04:41:59AM -0700, Richard Sharpe wrote: > Hi folks, > > I am attempting to implement SMB Direct (aka SMB over RDMA) for Samba. > > For historical, protocol and performance reasons I believe that I need > to write a character driver that offloads RDMA stuff to the kernel. > > Briefly, these reasons are: > > 1. Samba forks a new smbd when each incoming SMB connection arrives > > 2. SMB Over RDMA operates by first connecting to the server over TCP, > bringing up SMB, determining that the server supports RDMA and then > establishing an RDMA connection, bringing up SMB Direct and then > transporting SMB PDUs over that. > > 3. The current Windows client implementation pays no attention to the > port supplied to it by the server and always connects on port 4554.
So your issue is that when the transport is upgraded SMB performs a whole new connection setup to the common port and the server is expected to associate the new connection to the old based on a GUID in the first messages? How about this for a flow? - The master process listens on all relavent TCP and RDMA ports for incoming connections - At each incomming connection it forks and constructs a sub process for that connection. I think we can do this today with RDMA, but if not it should be doable with less effort than making your own kernel driver :) Sean might know for sure.. - The new smbd is now either a from scratch new connection (normal case today) or an 'upgrade' to an prior connection - If it is an upgrade, use some scheme to transfer the samba internal state from the old connection smbd to the new connection smbd That keeps your per-process model.. > However, I figure that I will eventually need to support situations > where there are multiple IB HCAs in a system, and I wondered if > there are any abstractions that allow me to do an ib_cm_listen > across multiple devices at once? Not really, you need to listen on every device. And you almost certainly need to use the RDMA CM interfaces (as Or mentioned), that will be mandatory to support iWarp, and it looks like MS is using the RDMA-CM protocol on IB as well. > 3. When I get a callback on one listen, cancel the others. Why? Wouldn't you listen for RDMA connections permanently, like for the TCP listen? >From what I read about the SMB protocol it looks completely valid to bypass the TCP first stage and go directly to RDMA. Or go from TCP to TCP, or RDMA to TCP, or whatever. Jason -- 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
