[ofa-general] [PATCH RFC] sharing userspace IB objects

[Or Gerlitz]

Roland Dreier wrote:
> 
>  > So, if both sides use a shared-context, they would need to implement a
>  > synchronization protocol (that is don't deliver established event to
>  > the active before the passive accepted).
> 
> I'm missing something -- how does the sharing affect the need for
> synchronization?

if its a non shared context, the passive side creates QP, then allocates 
and posts RX buffers to the it before accepting the connection request, 
so synchronization is achieved by the IB CM.

Now, we you want process A to create a QP and accept the connection, 
then hand it to process B which will allocate and post RX to this QP, we 
are out of sync with the active side, unless first process B gets the QP 
  and post RX, and second, process A does accept on the conn req.

> Given all this sharing we probably need a way to handle registering
> shared memory more efficiently.  But actually QP/CQ buffers only need
> to be registered once, since the key that the HCA uses to access the
> buffer is set at creation time, and the other processes don't need
> separate keys.

OK, thanks for clarifying that.

Or.