Dear all, I am a beginner of MPI, right now I try to use MPI_GATHERV in my code, the test code just gather the value of array A to store them in array B, but I found an error listed as follows,
'Fatal error in MPI_Gatherv: Invalid count, error stack: PMPI_Gatherv<398>: MPI_Gatherv failed <sbuf=004d96c0, scount=64,MPI_REAL, rbuf=0049AC0, rcnts=003DCB8, displs=003D4C68, MPI_REAL, root=0, MPI_COMM_WORLD> failed PMPI_Gatherv<317>: Negative count, value is -842150451’ Here I post my program with the email, I wonder anyone can help me to fix it or not? I guess my error is from the sending or receiving buffer and the displacement of the value stored, I tried to changed ‘B,jlen,idisp’ to ’ B(1,1), jlen(myid),idisp(myid)’ or other things, but I still cannot work it out. I am looking forward some help from you. Zhangping Wei my code is, PROGRAM MAIN IMPLICIT NONE INCLUDE 'mpif.h' INTEGER I,J,IWORK,JWORK,I1,I2,J1,J2 REAL A(16,16),B(16,16) INTEGER,ALLOCATABLE ::idisp(:),jlen(:) integer myid,numprocs,rc,ierr,istar,iend,jstar,jend integer status(MPI_STATUS_SIZE) CALL MPI_INIT(ierr) CALL MPI_COMM_RANK(MPI_COMM_WORLD,myid,ierr) CALL MPI_COMM_SIZE(MPI_COMM_WORLD,numprocs,ierr) ! PRINT *,'process ',myid, 'of',numprocs, 'is alive.' allocate(idisp(0:numprocs-1),jlen(0:numprocs-1)) DO J=1,16 DO I=1,16 A(I,J)=I+J B(I,J)=0.0 ENDDO ENDDO I1=1;I2=16;J1=1;J2=16 JWORK=(J2-J1)/numprocs+1 JSTAR=MIN(myid*JWORK+J1,J2+1) JEND=MIN(JSTAR+JWORK-1,J2) ISTAR=I1 IEND=I2 PRINT *,myid,istar,iend,jstar,jend jlen(myid)=16*(jend-jstar+1) idisp(myid)=16*(jstar-1) print *,myid,jlen(myid),idisp(myid) CALL MPI_GATHERV(A(1,jstar),jlen(myid),MPI_REAL, *B,jlen,idisp,MPI_REAL,0,MPI_COMM_WORLD,IERR) IF(myid.EQ.0)THEN DO J=1,16 DO I=1,16 PRINT *,I,J,B(I,J) ENDDO ENDDO ENDIF CALL MPI_Finalize(rc) END PROGRAM
