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
MPI_Scatterv (chunk, send_counts, displacements, MPI_CHAR, copychunk,
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,
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
Thanks in advance.