[openib-general] Re: CMA stuff

[Sean Hefty]

Caitlin Bestler wrote:
> The only sensible meaning for "backlog" is that it
> is a credit given by the application to the CMA. It
> is permission to make N callbacks with connection
> requests. Each callback decrements the credit.
> Each accept/reject restores a credit. This is
> totally analogous to having a single credit
> for how many in-flight requests a server allows
> a client to send, without any knowledge of how
> the client is structured internally or how that
> limit impacts the clients decisions.

This was the definition of backlog that I tried to push down into the IB CM. 
And while it sounds simple, it resulted in a complex implementation because of 
destruction issues.  I don't remember all of the problems now, but it was along 
the lines of having the listen destroyed before or simultaneously with an 
associated connect request being accepted/rejected/destroyed.  The same problems 
occur implementing backlog in the CMA.

For kernel clients that make use of a connection queue, backlog can be easily 
managed.  Clients simply reject requests that they are not ready to handle.

- Sean