On Mon, 2008-05-19 at 13:17 -0400, Talpey, Thomas wrote: > At 12:34 PM 5/19/2008, Tom Tucker wrote: > >When adapters have differing IRD limits, the RDMA transport will fail to > >connect properly. The RDMA transport should use the client's advertised > >inbound read limit when computing it's outbound read limit. For iWARP > >transports, there is no exchange of the IRD/ORD during connect request and > >so the only way to ensure compatability is to use the > >/proc/sys/sunrpc/svc_rdma/max_outbound_read_requests file to control > >server ORD. > > Well, technically the iWARP connection manager *currently* does not > exchange these values. I think the comment would be more accurate > if it said "in the absence of"... I'm not sure it really has anything to do with where it is implemented. The iWARP protocol(s) do not specify how or if IRD/ORD will be exchanged so this commit doesn't help them. The note is meant to be a hint to users of the transport how to get around potential connection issues between iWARP adapters with differing capabilities. The two spelling errors should be fixed though ;-) > > >-static void handle_connect_req(struct rdma_cm_id *new_cma_id) > >+static void handle_connect_req(struct rdma_cm_id *new_cma_id, u8 client_ird) > > While "u8" might be the limit of the implementations today, wouldn't "int" be > easier to understand, and more portable? > I think that 'int' might provoke the "wrath of Chuck". Unsigned something else -- > >+ /* Save client advertised inbound read limit for use later in accept. */ > >+ newxprt->sc_ord = client_ird; > >+ > and... > >+ /* > >+ * Limit ORD based on client limit, local device limit, and > >+ * configured svcrdma limit. > >+ */ > >+ newxprt->sc_ord = min((size_t)devattr.max_qp_rd_atom, newxprt->sc_ord); > >+ newxprt->sc_ord = min((size_t)svcrdma_ord, newxprt->sc_ord); > > Looks good, but it's a little odd that the value goes into sc_ord in one > routine, only to be changed before being used. I guess the device attrs > aren't handy at the time the connection is notified though, so ok. > Yes. It's the initial candidate for ORD that may be updated later based on configuration and/or device capabilities. > Tom. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
