MPI_Send/ MPI_Rcv don't work with more then 8182 double

[Paolo_M_]

Hi, I'm having some troubles with the attached code SendReceive.c. The idea is to open a dataset with process p-1 and then to distribute it to the remaining processes. This solution works when the variable ln (local number of elements) is less than 8182. When I increase the number of elements I've the following error: mpiexec -np 2 ./sendreceive 16366 Process 0 is receiving 8183 elements from process 1 Process 1 is sending 8183 elements to process 0 Fatal error in MPI_Recv: Other MPI error, error stack: MPI_Recv(224)...................: MPI_Recv(buf=0x2000590, count=8183, MPI_DOUBLE, src=1, tag=MPI_ANY_TAG, MPI_COMM_WORLD, status=0x1) failed PMPIDI_CH3I_Progress(623).......: fail failed pkt_RTS_handler(317)............: fail failed do_cts(662).....................: fail failed MPID_nem_lmt_dcp_start_recv(288): fail failed dcp_recv(154)...................: Internal MPI error! cannot read from remote process I'm using the student license of the intel implementation of mpi (obtained by installing Intel® Parallel Studio XE Cluster Edition (includes Fortran and C/C++)). Is this a limitation of the licence? Otherwise, what I'm doing wrong?

[Kevin_O_Intel1]

Hi,

It is not a limitation in the license.

Glancing at your code it looks like it is your buffer size that is the issue.

16322/2 = 8183... this the size of the buffer you declare

[Paolo_M_]

Hi Kevin,

as you can see in the code below the size of the buffer is ln, as the number of elements sent. Why should it be the problem?

buffer = (double*)calloc(ln, sizeof(double));

retCode = MPI_Ssend (buffer, ln, MPI_DOUBLE, i, 0, MPI_COMM_WORLD);

retCode = MPI_Recv (buffer, ln, MPI_DOUBLE, p-1, MPI_ANY_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);

[Kevin_O_Intel1]

Hi Paolo,

I think this issue would be better handled in this forum: https://software.intel.com/en-us/forums/intel-clusters-and-hpc-technology/

Kevin

[Paolo_M_]

Thank you Kevin,

I posted the issue in https://software.intel.com/en-us/forums/intel-clusters-and-hpc-technology/topic/691321