Can someone kindly reply?
On Tue, Apr 8, 2014 at 1:01 PM, Hamid Saeed <e.hamidsa...@gmail.com> wrote: > Hello, > I think that the MPI open its sockets even though the number of processor > is only 1 on the same machine? > regards. > > > On Tue, Apr 8, 2014 at 9:43 AM, Hamid Saeed <e.hamidsa...@gmail.com>wrote: > >> Hello all, >> >> I have a very basic question regarding MPI communication. >> >> In my Task, what i am doing is.. >> Comparing Scatterv and MPIO. >> 1) In scatterv, I scatter all the data to the other ranks and SCAN for >> the specific characters. >> MPI_Scatterv (chunk, send_counts, displacements, MPI_CHAR, copychunk, >> smallchunk_size, >> MPI_CHAR, 0, MPI_COMM_WORLD); >> & >> 2) On the other hand using MPIO, I have the data available in the shared >> memory and every rank searches in the specific chunk. >> MPI_File_open(MPI_COMM_WORLD, "170mb.txt", MPI_MODE_RDONLY, >> MPI_INFO_NULL, &in); >> here i assign every processor to search in a specific "chunk" >> >> >> My question is.. >> >> Why MPI_Scatterv using 1 processor takes more time then MPI_File_open? >> How does MPI sending and receiving takes place? >> >> I think using 1 processor does not include physical sending and >> receiving. Then why it consumes more clock? >> >> In the attachment you can observe the plots in which i performed some >> tests using both algorithms. >> >> Kindly explain briefly the mpi communication using 1 processor and >> multiple processors. >> >> >> Thanks in advance. >> >> Regards >> Hamid >> > > > > -- > Hamid > > -- _______________________________________________ Hamid Saeed CoSynth GmbH & Co. KG Escherweg 2 - 26121 Oldenburg - Germany Tel +49 441 9722 738 | Fax -278 http://www.cosynth.com _______________________________________________
