Peter is correct. We need to find out what K is. But we may never find out https://en.wikipedia.org/wiki/The_Trial
It would be fun if we could get some real-world dimesnions here and some real-world numbers. What range of numbers are these also? On 2 May 2018 at 15:21, Peter Kjellström <c...@nsc.liu.se> wrote: > On Wed, 2 May 2018 08:39:30 -0400 > Charles Antonelli <c...@umich.edu> wrote: > > > This seems to be crying out for MPI_Reduce. > > No, the described reduction cannot be implemented with MPI_Reduce (note > the need for partial sums along the axis). > > > Also in the previous solution given, I think you should do the > > MPI_Sends first. Doing the MPI_Receives first forces serialization. > > It needs that. The first thing that happens is that the first rank > skips the recv and sends its SCAL to the 2nd process that just posted > recv. > > Each process needs to complete the recv to know what to send (unless > you split it out into many more sends which is possible). > > What's the best solution depends on if this part is performance > critical and how large K is. > > /Peter K > > > Regards, > > Charles > ... > > > Something like (simplified psuedo code): > > > > > > if (not_first_along_K) > > > MPI_RECV(SCAL_tmp, previous) > > > SCAL += SCAL_tmp > > > > > > if (not_last_along_K) > > > MPI_SEND(SCAL, next) > > > > > > /Peter K > > > _______________________________________________ > > > users mailing list > > > users@lists.open-mpi.org > > > https://lists.open-mpi.org/mailman/listinfo/users > > > > > > -- > Sent from my Android device with K-9 Mail. Please excuse my brevity. > > _______________________________________________ > users mailing list > users@lists.open-mpi.org > https://lists.open-mpi.org/mailman/listinfo/users >
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