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C $Header$ |
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C $Name$ |
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|
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C-- File global_sum_singlecpu.F: Routines that perform global sum |
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C on a single CPU |
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#include "CPP_EEOPTIONS.h" |
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|
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CBOP |
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C !ROUTINE: GLOBAL_SUM_SINGLECPU_RL |
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|
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C !INTERFACE: |
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SUBROUTINE GLOBAL_SUM_SINGLECPU_RL( |
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I phiLocal, |
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O sumPhi, |
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I myThid ) |
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IMPLICIT NONE |
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C !DESCRIPTION: |
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C *==========================================================* |
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C | SUBROUTINE GLOBAL\_SUM\_SINGLECPU\_RL |
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C | o Handle sum for _RL data. |
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C *==========================================================* |
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C | Global sum of 2d array |
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C | independent of tiling as sum is performed on a single CPU |
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C | sum is performed in REAL*8 |
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C *==========================================================* |
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|
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C !USES: |
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C == Global data == |
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#include "SIZE.h" |
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#include "EEPARAMS.h" |
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#include "EESUPPORT.h" |
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#include "GLOBAL_SUM.h" |
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|
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C !INPUT/OUTPUT PARAMETERS: |
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C == Routine arguments == |
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C phiLocal :: local input array without overlap regions. |
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C sumPhi :: Result of sum. |
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C myThid :: My thread id. |
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_RL phiLocal(1:sNx,1:sNy,nSx,nSy) |
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_RL sumPhi |
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INTEGER myThid |
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|
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C !LOCAL VARIABLES: |
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C == Local variables == |
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C- type declaration of: sumAll, globalBuf : |
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C sumAll needs to have the same length as MPI_DOUBLE_PRECISION |
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INTEGER I,J |
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Real*8 globalBuf(Nx,Ny) |
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Real*8 sumAll |
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#ifdef ALLOW_USE_MPI |
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INTEGER npe |
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INTEGER lbuff, idest, itag |
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INTEGER istatus(MPI_STATUS_SIZE), ierr |
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#endif /* ALLOW_USE_MPI */ |
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CEOP |
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|
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C- note(jmc): do not see why we need this Barrier here + the one at the end ; |
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C however a) both are present in the standard version of global_sum ; |
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C b) with OpenMP on hugo, does not work if both are commented out |
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CALL BAR2( myThid ) |
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|
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C-- Gather local arrays |
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CALL GATHER_2D( globalBuf, phiLocal, myThid ) |
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|
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C-- Master thread does the communications and the global sum |
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C-- Master thread cannot start until everyone is ready: |
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CALL BAR2( myThid ) |
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_BEGIN_MASTER( myThid ) |
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|
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#ifdef ALLOW_USE_MPI |
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idest = 0 |
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itag = 0 |
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|
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IF ( mpiMyId.EQ.0 ) THEN |
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#endif |
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|
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C-- Process 0 sums the global array |
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sumAll = 0.d0 |
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DO J=1,Ny |
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DO I=1,Nx |
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sumAll = sumAll + globalBuf(I,J) |
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ENDDO |
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ENDDO |
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|
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#ifdef ALLOW_USE_MPI |
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C-- Process 0 sends result to all other processes |
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lbuff = 1 |
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DO npe = 1, numberOfProcs-1 |
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CALL MPI_SEND (sumAll, 1, MPI_DOUBLE_PRECISION, |
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& npe, itag, MPI_COMM_MODEL, ierr) |
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ENDDO |
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|
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ELSE |
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|
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C-- All proceses except 0 receive result from process 0 |
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CALL MPI_RECV (sumAll, 1, MPI_DOUBLE_PRECISION, |
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& idest, itag, MPI_COMM_MODEL, istatus, ierr) |
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|
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ENDIF |
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#endif /* not ALLOW_USE_MPI */ |
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|
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C-- Write solution to shared buffer (all threads can see it) |
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shareBufGSR8(1,1) = sumAll |
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|
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_END_MASTER( myThid ) |
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C-- Everyone wait for Master thread to be ready |
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CALL BAR2( myThid ) |
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|
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C-- set result for every threads |
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sumPhi = shareBufGSR8(1,1) |
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|
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C- note(jmc): do not see why we need this Barrier here (see comment @ the top) |
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CALL BAR2( myThid ) |
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|
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RETURN |
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END |
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