RE: [ofa-general] Re: [PATCH RFC] RDMA/CMA: Allocate PS_TCP portsfrom the host TCP port space.

Sean Hefty
2007-08-16T03:27:43Z

>It's not about being a niche. It's about creating a maintainable
>software net stack that has predictable behavior.
>
>Needing to reach out of the RDMA sandbox and reserve net stack resources
>away from itself travels a path we've consistently avoided.

We need to ensure that we're also creating a maintainable kernel. RDMA doesn't
use sockets, but that doesn't mean it's not part of the networking support
provided by the Linux kernel. Making blanket statements that RDMA should stay
within a sandbox is equivalent to saying that RDMA should duplicate any network
related functionality that it might need.

>>> I will NACK any patch that opens up sockets to eat up ports or
>>> anything stupid like that.
>
>Ditto for me as well.

I agree that using a socket is the wrong approach, but my guess is that it was
suggested as a possibility because of the attempt to keep RDMA in its 'sandbox'.
The iWarp architecture implements RDMA over TCP; it just doesn't use sockets.
The Linux network stack doesn't easily support this possibility. Are there any
reasonable ways to enable this to the degree necessary for iWarp?

- Sean