Changeset 10132 for NEMO/branches

Timestamp:

2018-09-17T14:57:19+02:00 (6 years ago)

Author:

dguibert

Message:

introduce BULL_GET_DIVISORS/BULL_MPI_DIMS_CREATE

These two options returns a tuple (jpni,jnpj) based on the full
list of divisors instead of the tuple with one equal to a power of 2.

File:

• NEMO/branches/2018/dev_r9759_HPC09_ESIWACE/src/OCE/LBC/mppini.F90 (modified) (3 diffs)

NEMO/branches/2018/dev_r9759_HPC09_ESIWACE/src/OCE/LBC/mppini.F90

@@ -738 +738 @@
       INTEGER, INTENT(in) ::   num_pes   ! The number of MPI processes we have
       !
-      INTEGER, PARAMETER :: nfactmax = 20
+      INTEGER, PARAMETER :: nfactmax = 40
       INTEGER :: nfact ! The no. of factors returned
       INTEGER :: ierr  ! Error flag
@@ -744 +744 @@
       INTEGER :: idiff, mindiff, imin ! For choosing pair of factors that are closest in value
       INTEGER, DIMENSION(nfactmax) :: ifact ! Array of factors
+      integer, dimension(2) :: pdims
       !!----------------------------------------------------------------------
       !
       ierr = 0
-      !
+#ifdef BULL_MPI_DIMS_CREATE
+      ! compute good (rectangular) domain decomposition
+      call MPI_Dims_create(num_pes, 2, pdims, ierr)
+      if(ierr == 0) then
+        write(numout, *) 'MPI_Dims_create: ',pdims
+        jpni=pdims(1)
+        jpnj=pdims(2)
+      else
+         WRITE (numout, *) 'WARNING: factorisation of number of PEs failed'
+         WRITE (numout, *) '       : using grid of ',num_pes,' x 1'
+         jpnj = 1
+         jpni = num_pes
+      endif
+      jpnij = jpni*jpnj
+#else
+#ifdef BULL_GET_DIVISORS
+      CALL get_divisors( ifact, nfactmax, nfact, num_pes, ierr )
+#else
       CALL factorise( ifact, nfactmax, nfact, num_pes, ierr )
+#endif
       !
       IF( nfact <= 1 ) THEN
@@ -771 +790 @@
       !
       jpnij = jpni*jpnj
+#endif
       !
    END SUBROUTINE mpp_init_partition
 
-
+   SUBROUTINE get_divisors( kfax, kmaxfax, knfax, kn, kerr )
+      !!----------------------------------------------------------------------
+      !!                     ***  ROUTINE factorise  ***
+      !!
+      !! ** Purpose :   A O(sqrt(n)) program that prints all divisors
+      !!                in sorted order
+      !! ** Method  :
+      !!----------------------------------------------------------------------
+      INTEGER                    , INTENT(in   ) ::   kn, kmaxfax
+      INTEGER                    , INTENT(  out) ::   kerr, knfax
+      INTEGER, DIMENSION(kmaxfax), INTENT(  out) ::   kfax
+      !
+      INTEGER :: ifac, jl, inu
+      kerr=0
+      inu = kn
+      knfax = 0
+      do ifac=1, sqrt(real(kn))
+          if(mod(kn,ifac) == 0) then
+               IF( knfax+2 > kmaxfax ) THEN
+                  kerr = 6
+                  write (*,*) 'FACTOR: insufficient space in factor array ', knfax
+                  return
+               ENDIF
+               knfax = knfax + 1 ! Add the factor to the list
+               kfax(knfax) = ifac
+               ! Store the other factor that goes with this one
+               knfax = knfax + 1
+               kfax(knfax) = kn/ifac
+               !WRITE (*,'(4(a,i))') 'ARPDBG, factors ',knfax-1,' & ',knfax,' are ', kfax(knfax-1),' and ',kfax(knfax)
+          endif
+      end do
+   END SUBROUTINE get_divisors
+ 
    SUBROUTINE factorise( kfax, kmaxfax, knfax, kn, kerr )
       !!----------------------------------------------------------------------