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joey_hylton
Beginner
36 Views

Help on re-distributing a matrix with mpi_alltoallv



Could someone kindly help me to re-distribute a matrix with mpi_alltoallv or anyother functions in Intel Fortran? Thanks in advance!

Say I have a matrix A(I,J) with I=2 and J=78

currently, A is distributed on 3 nodes along I:

node 1: A(1,1:J)
node 2: A(1,1:J)
node 3: none

I want to distribute it to:

node 1: A(1:I, 1:26)
node 2: A(1:I, 1:26)
node 3: A(1:I, 1:26)


I used a function as this:

mpi_alltoallv(B0,np0,dp0,mpi_double_complex,B1,np1,dp1,mpi_double_complex,mpi_comm_world,pierr)

I checked it:
node1: np0=(26 26 26), dp0=(0 26 52), np1=(26 26 26), dp1=(0 0 0)
node2: np0=(26 26 26), dp0=(0 26 52), np1=(26 26 26), dp1=(26 26 26)
node3: np0=(0 0 0), dp0=(0 0 0), np1=(0 0 0), dp1=(52 52 52)

where B0((j-1)*I+i)=A(i,j)

However, the prorgag has a deadlock!!!!!!!!!!!!!!!!!!!!!!

================================================================

I also tested with other case:
I=5; J=78 with two nodes:

A distribution:
node1: A(1:3,1:78)
node2: A(1:2,1:78)

I want to re-distribute it to:
node1: A(1:5,1:39)
node1: A(1:5,1:39)

Again with B0((j-1)*I+i)=A(i,j) :

mpi_alltoallv(B0,np0,dp0,mpi_double_complex,B1,np1,dp1,mpi_double_complex,mpi_comm_world,pierr)

I checked it:
node1: np0=(117 117), dp0=(0 117), np1=(117 117), dp1=(0 0)
node2: np0=(78 78), dp0=(0 78), np1=(78 78), dp1=(117 117)

This time, it gave a error:

node0:
node1: 13: Fatal error in MPI_Alltoallv: Pending request (no error), error stack:
MPI_Alltoallv(576): MPI_Alltoallv(sbuf=0x000000000517C690, scnts=0x0000000002EECC20, sdispls=0x0000000002EECBC0, MPI_DOUBLE_COMPLEX, rbuf=0x
0000000004F42470, rcnts=0x0000000002EECB60, rdispls=0x0000000002EECB00, MPI_DOUBLE_COMPLEX, MPI_COMM_WORLD) failed
(unknown)(): Pending request (no error)


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joey_hylton
Beginner
36 Views

Okay
I got something wrong over there.
I found it out.