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

[Tang, Changqing]

Thanks. I am thinking the similar thing of reserved port in TCP/IP world.

--CQ

> -----Original Message-----
> From: Hoang-Nam Nguyen [mailto:HNGUYEN at de.ibm.com]
> Sent: Wednesday, February 27, 2008 8:23 AM
> To: Tang, Changqing
> Cc: general at lists.openfabrics.org;
> general-bounces at lists.openfabrics.org
> Subject: Re: [ofa-general] Can we provide a qp_num when
> creating a QP ?
>
> 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
>
>