Merge branch release-2016 into release-2018

[alexxy/gromacs.git] / src / gromacs / taskassignment / resourcedivision.cpp

diff --git a/src/gromacs/taskassignment/resourcedivision.cpp b/src/gromacs/taskassignment/resourcedivision.cpp
index a195d6050159895129f61a01e6e7531c70530d20..015c8b68575771e7f078ccbcaa897aef394b21c3 100644 (file)
--- a/src/gromacs/taskassignment/resourcedivision.cpp
+++ b/src/gromacs/taskassignment/resourcedivision.cpp
@@ -216,6 +216,14 @@ gmx_unused static int get_tmpi_omp_thread_division(const gmx_hw_info_t *hwinfo,
      */
     if (ngpu > 0)
     {
+        if (hw_opt.nthreads_omp > 0)
+        {
+            /* In this case it is unclear if we should use 1 rank per GPU
+             * or more or less, so we require also setting the number of ranks.
+             */
+            gmx_fatal(FARGS, "When using GPUs, setting the number of OpenMP threads without specifying the number of ranks can lead to conflicting demands. Please specify the number of thread-MPI ranks as well (option -ntmpi).");
+        }
+
         nrank = ngpu;
 
         /* When the user sets nthreads_omp, we can end up oversubscribing CPU cores