Avoid PME tuning decreasing rcoulomb

[alexxy/gromacs.git] / src / programs / mdrun / pme_loadbal.c

diff --git a/src/programs/mdrun/pme_loadbal.c b/src/programs/mdrun/pme_loadbal.c
index 63efb07eea468fddd884f05295c33e71daf4fc58..d6fd68f37269d10692d625172706519c053c2cf3 100644 (file)
--- a/src/programs/mdrun/pme_loadbal.c
+++ b/src/programs/mdrun/pme_loadbal.c
@@ -36,7 +36,8 @@
 #include <config.h>
 #endif
 
-#include "smalloc.h"
+#include "gromacs/utility/smalloc.h"
+#include "types/commrec.h"
 #include "network.h"
 #include "calcgrid.h"
 #include "pme.h"
@@ -260,6 +261,15 @@ static gmx_bool pme_loadbal_increase_cutoff(pme_load_balancing_t  pme_lb,
     while (sp <= 1.001*pme_lb->setup[pme_lb->cur].spacing || !grid_ok);
 
     set->rcut_coulomb = pme_lb->cut_spacing*sp;
+    if (set->rcut_coulomb < pme_lb->rcut_coulomb_start)
+    {
+        /* This is unlikely, but can happen when e.g. continuing from
+         * a checkpoint after equilibration where the box shrank a lot.
+         * We want to avoid rcoulomb getting smaller than rvdw
+         * and there might be more issues with decreasing rcoulomb.
+         */
+        set->rcut_coulomb = pme_lb->rcut_coulomb_start;
+    }
 
     if (pme_lb->cutoff_scheme == ecutsVERLET)
     {
@@ -829,8 +839,8 @@ static void print_pme_loadbal_settings(pme_load_balancing_t pme_lb,
     {
         md_print_warn(cr, fplog,
                       "NOTE: PME load balancing increased the non-bonded workload by more than 50%%.\n"
-                      "      For better performance use (more) PME nodes (mdrun -npme),\n"
-                      "      or in case you are beyond the scaling limit, use less nodes in total.\n");
+                      "      For better performance, use (more) PME ranks (mdrun -npme),\n"
+                      "      or if you are beyond the scaling limit, use fewer total ranks (or nodes).\n");
     }
     else
     {