[ofa-general] Can we provide a qp_num when creating a QP ?

[Hoang-Nam Nguyen]

Hi,
>         I have asked this question before. To wire a QP connection,
> each side need to know
> peer's side port lid and qp_num. For MPI with many ranks, this is an
> alltoall exchange.
>
>         If we can create a QP with provided qp_num, then MPI does
> not need the qp_num
> exchange, for a QP-pair between two processes, MPI can figure out
> peer QP's qp_num. So
> we can eliminate the third-party channel to exchange information,
> and speedup the startup
> time.
>
>         Curently qp_num is always a return value from the driver. If
> we can suggest a qp_num
> when creating a QP, and the qp_num is already used, then IBV can
> either error out, or
> pick up another number for app.
We can not support this for ehca.
Regards
Nam