Hi Alexander
I have no objection to citing my "assertions" proposal in the subsetting
discussions. I do want to keep it clear that this proposal is intended to
be as simple as practical to implement, exploit and live with.
"Live with" applies to 3rd party library authors or anyone else who must
write MPI code but does not know and control the structure of the entire
application. That guy must "live with" the decisions made by whoever coded
the MPI_INIT piece. "Live with" also applies to whoever must test or
certify a specific MPI implementation.
Thanks - Dick
Dick Treumann - MPI Team/TCEM
IBM Systems & Technology Group
Dept 0lva / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601
Tele (845) 433-7846 Fax (845) 433-8363
"Supalov,
Alexander"
<alexander.supalo To
v_at_[hidden]> "MPI 2.2"
Sent by: <mpi-22_at_[hidden]>
mpi-22-bounces_at_li cc
sts.mpi-forum.org
Subject
Re: [Mpi-22] mpi-22 Digest, Vol 2,
04/26/2008 04:03 Issue 7
AM
Please respond to
"MPI 2.2"
<mpi-22_at_lists.mpi
-forum.org>
Dear Dick,
Thank you. Would you mind if I cite your proposal in the subsets
discussion? Yours looks like a good alternative to the thinking of some of
us that subsets might be very rich and mutable, and to Jeff's proposal on
hints I've already cited there with his permission.
Best regards.
Alexander
From: mpi-22-bounces_at_[hidden]
[mailto:mpi-22-bounces_at_[hidden]] On Behalf Of Richard Treumann
Sent: Thursday, April 24, 2008 6:16 PM
To: MPI 2.2
Subject: Re: [Mpi-22] mpi-22 Digest, Vol 2, Issue 7
Dick Treumann - MPI Team/TCEM
IBM Systems & Technology Group
Dept 0lva / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601
Tele (845) 433-7846 Fax (845) 433-8363
mpi-22-bounces_at_[hidden] wrote on 04/24/2008 11:33:42 AM:
> Hi,
>
> Note that this is an argument for making the assertions optional: those
> who don't care don't have to use them. Those who care should use them
> correctly or else. As usual.
>
> Best regards.
>
> Alexander
>
Hi Alexander
The assertions are optional in this proposal. If this is added to the MPI
standard the minimal impacts (day one impacts) are:
==
To application writers (none) - MPI_INIT and MPI_INIT_THREAD still work.
MPI_INIT_THREAD_xxx can be
passed 0 (zero) as the assertions bit vector.
To MPI Implementors (small) - subroutine MPI_INIT_THREAD_xxx can be a clone
of MPI_INIT_THREAD under the covers. If the Forum decides the query
function is for asking what assertions are being honored, the
implementation can just return "none" to every query. If there is also a
query for what assertions have been made then there are a few more lines of
code the implementor must write to preserve the value so it can be
returned(maybe 10 lines)
Writers of opaque libraries (small) - call the query function at library
init time and if any assertions are found, issue an error message and kill
the job. This is awkward for a library that wants to support every MPI
whether it has implemented the new query function or not.
==
As MPI implementations begin to take advantage of assertions there is more
work for the MPI implementor and the library author must begin to think
about whether his customer will be upset if the library simply outlaws all
assertions.
The library author will never be wrong if he simply forbids assertions
forever. If they become valuable he will feel the pressure to work it out.
The MPI implementor will never be wrong if he adds the API but simply
ignores assertions forever. If they become valuable he will feel the
pressure to honor some at least.
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