From: Berk Hess <hess@kth.se>
Date: Wed, 17 Oct 2018 20:37:58 +0000 (+0200)
Subject: Add env.var. to disable update groups
X-Git-Url: http://biod.pnpi.spb.ru/gitweb/?a=commitdiff_plain;h=77097d05bdb07e60386dd4edef75dcabe4268617;p=alexxy%2Fgromacs.git

Add env.var. to disable update groups

Change-Id: Iba4d9636f2da01fa1bc9e003446621c743fb9114
---

diff --git a/docs/user-guide/environment-variables.rst b/docs/user-guide/environment-variables.rst
index 61ef25443e..a03d2958ad 100644
--- a/docs/user-guide/environment-variables.rst
+++ b/docs/user-guide/environment-variables.rst
@@ -316,6 +316,10 @@ Performance and Run Control
         turns off solvent optimizations; automatic if ``GMX_NB_GENERIC``
         is enabled.
 
+``GMX_NO_UPDATEGROUPS``
+        turns off update groups. May allow for a decomposition of more
+        domains for small systems at the cost of communication during update.
+
 ``GMX_NSCELL_NCG``
         the ideal number of charge groups per neighbor searching grid cell is hard-coded
         to a value of 10. Setting this environment variable to any other integer value overrides this hard-coded
diff --git a/src/gromacs/domdec/domdec.cpp b/src/gromacs/domdec/domdec.cpp
index 03371c1994..48c3f84963 100644
--- a/src/gromacs/domdec/domdec.cpp
+++ b/src/gromacs/domdec/domdec.cpp
@@ -2088,7 +2088,9 @@ static void setupUpdateGroups(const gmx::MDLogger &mdlog,
     }
 
     comm->updateGroupingPerMoleculetype = gmx::makeUpdateGroups(mtop);
-    comm->useUpdateGroups               = !comm->updateGroupingPerMoleculetype.empty();
+    comm->useUpdateGroups               =
+        (!comm->updateGroupingPerMoleculetype.empty() &&
+         getenv("GMX_NO_UPDATEGROUPS") == nullptr);
 
     if (comm->useUpdateGroups)
     {