[Mpi-forum] Persistence Working Group Proposed
jsquyres at cisco.com
Thu Apr 2 14:36:33 CDT 2009
Tony -- did this group get launched? Cisco would be interested.
On Feb 25, 2009, at 1:17 PM, Anthony Skjellum wrote:
> Dick, there are plenty of one-end optimizations that are possible
> The current technology is "half channels" and we want "whole
> channels" too.
> Binding an actual channel (which I did propose in MPI-2) is also
> possible for further optimization, and I am open to that as well.
> That makes a FIFO between sender and receiver, with single credit.
> I agree that a channel is desirable also. We would make it part of
> the discussion. It is easy enough to specify...
> ----- Original Message -----
> From: "Richard Treumann" <treumann at us.ibm.com>
> To: "Main MPI Forum mailing list" <mpi-forum at lists.mpi-forum.org>
> Sent: Wednesday, February 25, 2009 12:11:30 PM GMT -06:00 US/Canada
> Subject: Re: [Mpi-forum] Persistence Working Group Proposed
> In my opinion the lack of enthusiasm for point to point persistent
> operations does not tell us much about the usefulness of persistent
> operations in general. When the MPI-1 Forum decided an
> MPI_Isend_init or MPI_Irecv_init must be a local operation and that
> an MPI_Start of a persistent send on one side must match any form of
> receive (persistent or not) on the other (and vice versa) most of
> the opportunity for optimization was lost.
> For a persistent collective to be fully optimized, the MPI library
> probably must be able to do collective communication at the CC_INIT
> and return to each task a persistent request handle that is
> irrevocably bound to all the handles created at the other tasks by
> this collective operation. It should not be valid to create two
> persistent BCAST requests at the root with different send buffers
> and one persistent BCAST at the non-roots just so root could BCAST
> from either buffer. (even if somebody thinks that would be a cool
> bit of generality)
> Dick Treumann - MPI Team
> IBM Systems & Technology Group
> Dept X2ZA / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601
> Tele (845) 433-7846 Fax (845) 433-8363
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> Anthony Skjellum, PhD
> Professor and Chair
> Dept. of Computer and Information Sciences
> University of Alabama at Birmingham
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