Re: QoS in local SA entity

Or Gerlitz
2009-11-10T05:51:06Z

Jason Gunthorpe wrote:
> The extra info in rdma_resolve_addr2 carries the IB specific path information from the rdma_getaddrinfo module to the kernel for the address pair. The entire purpose of AF_IB is to let user space tell the kernel it does not want a kernel side ND and PR query, instead user space will provide all the information.
The kernel patches posted by Sean replace the ND/PR flow with a two
steps process, first specifying a DGID to the kernel next specifying a
PATH. My suggestion is to have a librdmacm initiated bind before the
sending the DGID to the kernel, this way AF_INET would be supported
perfectly under the slight limitation that the source address <device,
port, pkey> tuple would be chosen by route lookup and not by the
neigh->dev that what resolved by the kernel ND. This is only when the
modified flow of librdmacm is taken (e.g under user specification with
environment variable etc).

--If-- on top of that you want to add AF_IB, we may be able to do that,
but I don't see why the whole thing should be made for AF_IB only.

> Think of it this way, ACM takes over the entire process of what AF_INET does in the kernel. AF_INET talks directly to the IB CM module in the kernel. Thus, it also makes sense that ACM would need to talk to IB CM directly as well. AF_IB is that direct connection.

I don't agree we must state it this way. I see ACM as an alternative way
for AF_INET to resolve ND/PR.