Beware that MPI-request-free on active buffers is valid but evil. You CANNOT be sure when the buffer is available for reuse.
There was a sentence or paragraph added yo MPI 2.2 describing exactly this case. Sent from my PDA. No type good. On Nov 23, 2010, at 5:36 PM, Sébastien Boisvert <sebastien.boisver...@ulaval.ca> wrote: > Le mardi 23 novembre 2010 à 17:28 -0500, George Bosilca a écrit : >> Sebastien, >> >> Using MPI_Isend doesn't guarantee asynchronous progress. As you might be >> aware, the non-blocking communications are guaranteed to progress only when >> the application is in the MPI library. Currently very few MPI >> implementations progress asynchronously (and unfortunately Open MPI is not >> one of them). >> > > Regardless, I just need the non-blocking behavior. > I call MPI_Request_free just after MPI_Isend, and I use a ring allocator > to allocate message buffers. > > Message recipients just reply with another message to the source, using > a NULL buffer. > > The sender waits for the reply before sending the next message. > > And it works for assembling bacterial genomes on many MPI ranks: > > ... > Rank 0: 162 contigs/4576725 nucleotides > > Rank 0 reports the elapsed time, Tue Nov 23 01:35:48 2010 > ---> Step: Collection of fusions > Elapsed time: 0 seconds > Since beginning: 17 minutes, 33 seconds > > Elapsed time for each step, Tue Nov 23 01:35:48 2010 > > Beginning of computation: 1 seconds > Distribution of sequence reads: 7 minutes, 49 seconds > Distribution of vertices: 19 seconds > Calculation of coverage distribution: 1 seconds > Distribution of edges: 29 seconds > Indexing of sequence reads: 1 seconds > Computation of seeds: 2 minutes, 33 seconds > Computation of library sizes: 1 minutes, 47 seconds > Extension of seeds: 3 minutes, 34 seconds > Computation of fusions: 59 seconds > Collection of fusions: 0 seconds > Completion of the assembly: 17 minutes, 33 seconds > > Rank 0 wrote Ecoli-THEONE.CoverageDistribution.txt > Rank 0 wrote Ecoli-THEONE.fasta > Rank 0 wrote Ecoli-THEONE.ReceivedMessages.txt > Rank 0 wrote Ecoli-THEONE.Library0.txt > Rank 0 wrote Ecoli-THEONE.Library1.txt > > Au revoir ! > > >> george. >> >> On Nov 23, 2010, at 17:17 , Sébastien Boisvert wrote: >> >>> I now use MPI_Isend, so the problem is no more. >> >> >> _______________________________________________ >> devel mailing list >> de...@open-mpi.org >> http://www.open-mpi.org/mailman/listinfo.cgi/devel > > -- > M. Sébastien Boisvert > Étudiant au doctorat en physiologie-endocrinologie à l'Université Laval > Boursier des Instituts de recherche en santé du Canada > Équipe du Professeur Jacques Corbeil > > Centre de recherche en infectiologie de l'Université Laval > Local R-61B > 2705, boulevard Laurier > Québec, Québec > Canada G1V 4G2 > Téléphone: 418 525 4444 46342 > > Courriel: s...@boisvert.info > Web: http://boisvert.info > > "Innovation comes only from an assault on the unknown" -Sydney Brenner > > _______________________________________________ > devel mailing list > de...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/devel
