[openib-general] Re: Mellanox HCAs: outstanding RDMAs

[Talpey, Thomas]

At 10:40 AM 6/6/2006, Roland Dreier wrote:
>    Thomas> This is the difference between "may" and "must". The value
>    Thomas> is provided, but I don't see anything in the spec that
>    Thomas> makes a requirement on its enforcement. Table 107 says the
>    Thomas> consumer can query it, that's about as close as it
>    Thomas> comes. There's some discussion about CM exchange too.
>
>This seems like a very strained interpretation of the spec.  For

I don't see how strained has anything to do with it. It's not saying anything
either way. So, a legal implementation can make either choice. We're
talking about the spec!

But, it really doesn't matter. The point is, an upper layer should be paying
attention to the number of RDMA Reads it posts, or else suffer either the
queue-stalling or connection-failing consequences. Bad stuff either way.

Tom.


>example, there's no explicit language in the IB spec that requires an
>HCA to use the destination LID passed via a modify QP operation, but I
>don't think anyone would seriously argue that an implementation that
>sent messages to some other random destination was compliant.
>
>In the same way, if I pass a limit for the number of outstanding
>RDMA/atomic operations in to a modify QP operation, I would expect the
>HCA to use that limit.
>
> - R.