source/cluster/wham/src/work_partition.F

   1 #ifdef MPI
   2       subroutine work_partition(lprint,ncon_work)
   3 c Split the conformations between processors
   4       implicit none
   5       include "DIMENSIONS"
   6       include "sizesclu.dat"
   7       include "mpif.h"
   8       include "COMMON.IOUNITS"
   9       include "COMMON.CLUSTER"
  10       include "COMMON.MPI"
  11       integer n,chunk,i,j,ii,remainder
  12       integer kolor,key,ierror,errcode,ncon_work
  13       logical lprint
  14 C
  15 C Divide conformations between processors; the first and
  16 C the last conformation to handle by ith processor is stored in
  17 C indstart(i) and indend(i), respectively.
  18 C
  19 C First try to assign equal number of conformations to each processor.
  20 C
  21         n=ncon_work
  22         write (iout,*) "n=",n," nprocs=",nprocs
  23         indstart(0)=1
  24         chunk = N/nprocs
  25         scount(0) = chunk
  26 c        print *,"i",0," indstart",indstart(0)," scount",
  27 c     &     scount(0)
  28         do i=1,nprocs-1
  29           indstart(i)=chunk+indstart(i-1)
  30           scount(i)=scount(i-1)
  31 c          print *,"i",i," indstart",indstart(i)," scount",
  32 c     &     scount(i)
  33         enddo
  34 C
  35 C Determine how many conformations remained yet unassigned.
  36 C
  37         remainder=N-(indstart(nprocs-1)
  38      &    +scount(nprocs-1)-1)
  39 c        print *,"remainder",remainder
  40 C
  41 C Assign the remainder conformations to consecutive processors, starting
  42 C from the lowest rank; this continues until the list is exhausted.
  43 C
  44         if (remainder .gt. 0) then
  45           do i=1,remainder
  46             scount(i-1) = scount(i-1) + 1
  47             indstart(i) = indstart(i) + i
  48           enddo
  49           do i=remainder+1,nprocs-1
  50             indstart(i) = indstart(i) + remainder
  51           enddo
  52         endif
  53
  54         indstart(nprocs)=N+1
  55         scount(nprocs)=0
  56
  57         do i=0,NProcs
  58           indend(i)=indstart(i)+scount(i)-1
  59           idispl(i)=indstart(i)-1
  60         enddo
  61
  62         N=0
  63         do i=0,Nprocs-1
  64           N=N+indend(i)-indstart(i)+1
  65         enddo
  66
  67 c        print *,"N",n," NCON_WORK",ncon_work
  68         if (N.ne.ncon_work) then
  69           write (iout,*) "!!! Checksum error on processor",me,
  70      &      n,ncon_work
  71           call flush(iout)
  72           call MPI_Abort( MPI_COMM_WORLD, Ierror, Errcode )
  73         endif
  74
  75       if (lprint) then
  76         write (iout,*) "Partition of work between processors"
  77           do i=0,nprocs-1
  78             write (iout,'(a,i5,a,i7,a,i7,a,i7)')
  79      &        "Processor",i," indstart",indstart(i),
  80      &        " indend",indend(i)," count",scount(i)
  81           enddo
  82       endif
  83       return
  84       end
  85 #endif