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C $Header: /u/gcmpack/models/MITgcmUV/eesupp/src/global_max.F,v 1.2 1998/04/23 20:37:30 cnh Exp $ |
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|
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C-- File global_max.F: Routines that perform global max reduction on an array |
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C of thread values. |
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C Contents |
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C o global_max_r4 |
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C o global_max_r8 |
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#include "CPP_EEOPTIONS.h" |
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|
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CStartOfInterface |
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SUBROUTINE GLOBAL_MAX_R4( |
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I phi, |
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O maxPhi, |
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I myThid ) |
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C /==========================================================\ |
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C | SUBROUTINE GLOBAL_MAX_R4 | |
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C | o Handle max for real*4 data. | |
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C |==========================================================| |
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C | Perform max on array of one value per thread and then | |
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C | max result of all the processes. | |
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C | Notes | |
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C | ===== | |
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C | Within a process only one thread does the max, each | |
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C | thread is assumed to have already maxed its local data. | |
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C | The same thread also does the inter-process max for | |
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C | example with MPI and then writes the result into a shared| |
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C | location. All threads wait until the max is avaiailable. | |
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C \==========================================================/ |
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|
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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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|
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C == Routine arguments == |
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C phi - Array to be maxed. |
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C maxPhi - Result of max. |
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C myThid - My thread id. |
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Real*4 phi(lShare4,MAX_NO_THREADS) |
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Real*4 maxPhi |
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INTEGER myThid |
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CEndOfInterface |
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|
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C == Local variables == |
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C I - Loop counters |
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C mpiRC - MPI return code |
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INTEGER I |
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Real*4 tmp |
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#ifdef ALLOW_USE_MPI |
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INTEGER mpiRC |
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#endif /* ALLOW_USE_MPI */ |
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|
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C-- Can't start until everyone is ready |
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_BARRIER |
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|
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C-- Max within the process first |
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_BEGIN_MASTER( myThid ) |
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tmp = phi(1,1) |
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DO I=2,nThreads |
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tmp = MAX(tmp,phi(1,I)) |
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ENDDO |
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maxPhi = tmp |
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#ifdef ALLOW_USE_MPI |
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#ifndef ALWAYS_USE_MPI |
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IF ( usingMPI ) THEN |
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#endif |
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CALL MPI_Allreduce(tmp,maxPhi,1,MPI_REAL,MPI_MAX, |
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& MPI_COMM_WORLD,mpiRC) |
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#ifndef ALWAYS_USE_MPI |
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ENDIF |
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#endif |
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#endif /* ALLOW_USE_MPI */ |
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phi(1,1) = maxPhi |
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_END_MASTER( myThid ) |
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C-- |
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_BARRIER |
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C |
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RETURN |
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END |
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|
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|
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CStartOfInterface |
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SUBROUTINE GLOBAL_MAX_R8( |
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I phi, |
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O maxPhi, |
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I myThid ) |
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C /==========================================================\ |
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C | SUBROUTINE GLOBAL_MAX_R8 | |
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C | o Handle max for real*8 data. | |
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C |==========================================================| |
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C | Perform max on array of one value per thread and then | |
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C | max result of all the processes. | |
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C | Notes | |
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C | ===== | |
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C | Within a process only one thread does the max, each | |
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C | thread is assumed to have already maxed its local data. | |
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C | The same thread also does the inter-process max for | |
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C | example with MPI and then writes the result into a shared| |
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C | location. All threads wait until the max is avaiailable. | |
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C \==========================================================/ |
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|
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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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|
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C === Routine arguments === |
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C phi - Array to be maxed. |
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C maxPhi - Result of max. |
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C myThid - My thread id. |
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Real*8 phi(lShare8,MAX_NO_THREADS) |
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Real*8 maxPhi |
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INTEGER myThid |
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CEndOfInterface |
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|
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C === Local variables === |
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C I - Loop counters |
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C mpiRC - MPI return code |
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INTEGER I |
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Real*8 tmp |
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#ifdef ALLOW_USE_MPI |
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INTEGER mpiRC |
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#endif /* ALLOW_USE_MPI */ |
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|
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C-- Can't start until everyone is ready |
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_BARRIER |
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|
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C-- Max within the process first |
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_BEGIN_MASTER( myThid ) |
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tmp = phi(1,1) |
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DO I=2,nThreads |
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tmp = MAX(tmp,phi(1,I)) |
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ENDDO |
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maxPhi = tmp |
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#ifdef ALLOW_USE_MPI |
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#ifndef ALWAYS_USE_MPI |
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IF ( usingMPI ) THEN |
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#endif |
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CALL MPI_Allreduce(tmp,maxPhi,1,MPI_DOUBLE_PRECISION,MPI_MAX, |
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& MPI_COMM_WORLD,mpiRC) |
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#ifndef ALWAYS_USE_MPI |
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ENDIF |
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#endif |
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#endif /* ALLOW_USE_MPI */ |
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C-- Write solution to place where all threads can see it |
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phi(1,1) = maxPhi |
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_END_MASTER( myThid ) |
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|
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C-- Don't leave until we are sure that the max is done |
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_BARRIER |
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C |
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RETURN |
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END |
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