From a859b734ea53fcc798a8e403854f239d87c3a018 Mon Sep 17 00:00:00 2001
From: Paul Romano <paul.k.romano@gmail.com>
Date: Mon, 8 Jan 2018 13:01:32 -0600
Subject: [PATCH] Allow OMP_SCHEDULE to control schedule of main parallel do
 loop

---
 src/initialize.F90 | 11 +++++++++++
 src/simulation.F90 |  2 +-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/initialize.F90 b/src/initialize.F90
index 392e8d6bab..dd7894f96b 100644
--- a/src/initialize.F90
+++ b/src/initialize.F90
@@ -45,6 +45,9 @@ contains
     integer, intent(in), optional :: intracomm  ! MPI intracommunicator
 
     integer :: err
+#ifdef _OPENMP
+    character(MAX_WORD_LEN) :: envvar
+#endif
 
     ! Copy the communicator to a new variable. This is done to avoid changing
     ! the signature of this subroutine. If MPI is being used but no communicator
@@ -76,6 +79,14 @@ contains
     call initialize_mpi(comm)
 #endif
 
+#ifdef _OPENMP
+    ! Change schedule of main parallel-do loop if OMP_SCHEDULE is set
+    call get_environment_variable("OMP_SCHEDULE", envvar)
+    if (len_trim(envvar) == 0) then
+      call omp_set_schedule(omp_sched_static, 0)
+    end if
+#endif
+
     ! Initialize HDF5 interface
     call hdf5_initialize()
 
diff --git a/src/simulation.F90 b/src/simulation.F90
index e8997fc9b8..c80954f3f9 100644
--- a/src/simulation.F90
+++ b/src/simulation.F90
@@ -100,7 +100,7 @@ contains
 
       ! ====================================================================
       ! LOOP OVER PARTICLES
-!$omp parallel do schedule(static) firstprivate(p) copyin(tally_derivs)
+!$omp parallel do schedule(runtime) firstprivate(p) copyin(tally_derivs)
       PARTICLE_LOOP: do i_work = 1, work
         current_work = i_work