Re: more non-blocking collective discussion

Rolf Rabenseifner (Rabenseifner@RUS.Uni-Stuttgart.DE)
Thu, 6 Feb 1997 14:02:40 +0100 (MEZ)

Bill,

you summarized:
> 1. remove all nonblocking calls as requested by the Forum.

and in James' minutes:
> => Chapter authors will reconsider how their chapter can survive
> without non-blocking collective operations.

I believe also we have to reconsider, but we have not the order
to remove them at all.

> 4. Replace with "two-face" versions
> 4. Doesn't solve IACCEPT problem (as discussed in previous note).

Yes, but two-face solves all problems with ISPAWN!
Nobody forces us to handle ISPAWN and IACCEPT in the same way!

Therefore for ISPAWN and MPI_ISPAWN_MULTIPLE I propose:

We should have 2 alternatives in the draft for
4.3.4 Nonblocking requests

a) MPI_ISPAWN and MPI_ISPAWN_MULTIPLE as defined in the Jan. draft
b) MPI_SPAWN_START, MPI_SPAWN_END, MPI_SPAWN_MULTIPLE_START and
MPI_SPAWN_MULTIPLE_END with the semantics of the new section
"two-phase collective communication".

And the 3 alternatives to vote: a), or b), or nothing.

What is your opinion about 2-phase and ISPAWN?

And for IACCEPT it seems necessary to have a non-blocking interface
to check whether an additional client tries to connect.
This must not be the full formalism of request handles.

But it can be a mechanism like IPROBE!
Is this an idea worth to think about a little bit more?

Rolf