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<p>Tony <br>
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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.<br>
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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)<br>
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Dick Treumann - MPI Team <br>
IBM Systems & Technology Group<br>
Dept X2ZA / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601<br>
Tele (845) 433-7846 Fax (845) 433-8363<br>
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