From a7522080a585bffffbda6fdaec60728ed8a6f455 Mon Sep 17 00:00:00 2001
From: Anton Steketee <anton.steketee@anu.edu.au>
Date: Thu, 2 May 2024 15:25:08 +1000
Subject: [PATCH] Make nprocs optional

---
 .../cicedyn/infrastructure/ice_domain.F90     | 38 +++++++++----------
 cicecore/shared/ice_distribution.F90          |  2 +-
 configuration/scripts/ice_in                  |  2 +-
 3 files changed, 19 insertions(+), 23 deletions(-)

diff --git a/cicecore/cicedyn/infrastructure/ice_domain.F90 b/cicecore/cicedyn/infrastructure/ice_domain.F90
index 87d181a51..74ac62b79 100644
--- a/cicecore/cicedyn/infrastructure/ice_domain.F90
+++ b/cicecore/cicedyn/infrastructure/ice_domain.F90
@@ -90,7 +90,6 @@ module ice_domain
     integer (int_kind) :: &
        nprocs                ! num of processors
 
-        
 !***********************************************************************
 
  contains
@@ -224,18 +223,25 @@ subroutine init_domain_blocks
    call broadcast_scalar(nx_global,         master_task)
    call broadcast_scalar(ny_global,         master_task)
 
-   ! Automatically determine max_blocks if not set.
-   if (my_task == master_task) then
-      if (max_blocks < 1) then
-         call proc_decomposition(nprocs, nprocs_x, nprocs_y)
-         max_blocks=((nx_global-1)/block_size_x/nprocs_x+1) * &
-                     ((ny_global-1)/block_size_y/nprocs_y+1)
-         max_blocks=max(1,max_blocks)
-         write(nu_diag,'(/,a52,i6,/)') &
-            '(ice_domain): max_block < 1: max_block estimated to ',max_blocks
-      endif
+   ! Set nprocs if not set in namelist
+   if (nprocs .eq. -1) then
+      nprocs = get_num_procs()
+   else if (nprocs .ne. get_num_procs()) then
+      write(nu_diag,*) subname,' ERROR: nprocs, get_num_procs = ',nprocs,get_num_procs()
+      call abort_ice(subname//' ERROR: Input nprocs not same as system request', file=__FILE__, line=__LINE__)
+   endif
+
+   ! Determine max_blocks if not set
+   if (max_blocks < 1) then
+      call proc_decomposition(nprocs, nprocs_x, nprocs_y)
+      max_blocks=((nx_global-1)/block_size_x/nprocs_x+1) * &
+                  ((ny_global-1)/block_size_y/nprocs_y+1)
+      max_blocks=max(1,max_blocks)
+      write(nu_diag,'(/,a52,i6,/)') &
+         '(ice_domain): max_block < 1: max_block estimated to ',max_blocks
    endif
    
+   
 !----------------------------------------------------------------------
 !
 !  perform some basic checks on domain
@@ -247,16 +253,6 @@ subroutine init_domain_blocks
       !*** domain size zero or negative
       !***
       call abort_ice(subname//' ERROR: Invalid domain: size < 1', file=__FILE__, line=__LINE__) ! no domain
-   else if (nprocs /= get_num_procs()) then
-      !***
-      !*** input nprocs does not match system (eg MPI) request
-      !***
-#if (defined CESMCOUPLED)
-      nprocs = get_num_procs()
-#else
-      write(nu_diag,*) subname,' ERROR: nprocs, get_num_procs = ',nprocs,get_num_procs()
-      call abort_ice(subname//' ERROR: Input nprocs not same as system request', file=__FILE__, line=__LINE__)
-#endif
    else if (nghost < 1) then
       !***
       !*** must have at least 1 layer of ghost cells
diff --git a/cicecore/shared/ice_distribution.F90 b/cicecore/shared/ice_distribution.F90
index 0ba62f4a2..6e06069ab 100644
--- a/cicecore/shared/ice_distribution.F90
+++ b/cicecore/shared/ice_distribution.F90
@@ -42,7 +42,7 @@ module ice_distribution
              ice_distributionGetBlockLoc, &
              ice_distributionGetBlockID, &
              create_local_block_ids, &
-             proc_decomposition ! mli: add
+             proc_decomposition 
 
    character (char_len), public :: &
        processor_shape       ! 'square-pop' (approx) POP default config
diff --git a/configuration/scripts/ice_in b/configuration/scripts/ice_in
index 63a97d7d8..ad29e05ce 100644
--- a/configuration/scripts/ice_in
+++ b/configuration/scripts/ice_in
@@ -302,7 +302,7 @@
 /
 
 &domain_nml
-    nprocs = 4
+    nprocs            = -1
     nx_global         = 100
     ny_global         = 116
     block_size_x      = 25