Hey Bill, I took a look at the documentation for MPI_Scatter(), but I noticed that you need buffers to use it. My supervisor wasn't really happy with using buffers, and for that reason the code that I am writing is only using blocking routines, which will make my life a tad bit harder due to the fact that i have to avoid a deadlock, i believe it's called. I know it might not make sense due to the way MPI works, but is there any Scatter-like function that does not use buffers?
NB: I haven't looked through that book yet, so i am not sure whether they provide any non-buffer examples. Alex On Wed, Jul 21, 2010 at 10:48 AM, Bill Rankin <bill.ran...@sas.com> wrote: > Depending on the datatype and its order in memory, the “Block,*” and > “*,Block” (which we used to call “slabs” in 3D) may be implemented by a > simple scatter/gather call in MPI. The “Block,Block” distribution is a > little more complex, but if you take advantage of MPI’s derived datatypes, > you may be able to reference an arbitrary 3D sub-space as a single data > entity and then use gather/scatter with that. > > > > I recommend that look through some of the examples in “MPI – The Complete > Reference (Vol. 1)” by Snir, et.al. for use of MPI_Gather(), > MPI_Scatter(), as well as the section on user-defined datatypes. Section > 5.2 of “Using MPI” by Gropp, Lusk and Skjellum has an example code for an > N-Body Problem which you may find useful. > > > > Hope this helps. > > > > -bill > > > > > > *From:* users-boun...@open-mpi.org [mailto:users-boun...@open-mpi.org] *On > Behalf Of *Alexandru Blidaru > *Sent:* Tuesday, July 20, 2010 10:54 AM > *To:* Open MPI Users > *Subject:* Re: [OMPI users] Partitioning problem set data > > > > If there is an already existing implementation of the *Block or Block* > methods that splits the array and sends the individual pieces to > the proper nodes, can you point me to it please? > > On Tue, Jul 20, 2010 at 9:52 AM, Alexandru Blidaru <alexs...@gmail.com> > wrote: > > Hi, > > > > I have a 3D array, which I need to split into equal n parts, so that each > part would run on a different node. I found the picture in the attachment > from this website ( > https://computing.llnl.gov/tutorials/parallel_comp/#DesignPartitioning) on > the different ways to partition data. I am interested in the block methods, > as the cyclic methods wouldn't really work for me at all. Obviously the *, > BLOCK and the BLOCK, * methods would be really easy to implement for 3D > arrays, assuming that the 2D picture would be looking at the array from the > top. My question is if there are other better ways to do it from a > performance standpoint? > > > > Thanks for your replies, > > Alex > > > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users >
