Limit the depth of the gravity tasks being split.

src/cell.h

@@ -607,7 +607,7 @@ __attribute__((always_inline)) INLINE static int cell_can_split_pair_gravity_tas
     const struct cell *c) {
 
   /* Is the cell split ? */
-  return c->split;
+  return c->split && c->depth < space_subdepth_grav;
 }
 
 /**
@@ -620,7 +620,7 @@ __attribute__((always_inline)) INLINE static int cell_can_split_self_gravity_tas
     const struct cell *c) {
 
   /* Is the cell split ? */
-  return c->split;
+  return c->split && c->depth < space_subdepth_grav;
 }
 
 /**

src/space.c

@@ -66,6 +66,7 @@ int space_subsize_pair_hydro = space_subsize_pair_hydro_default;
 int space_subsize_self_hydro = space_subsize_self_hydro_default;
 int space_subsize_pair_grav = space_subsize_pair_grav_default;
 int space_subsize_self_grav = space_subsize_self_grav_default;
+int space_subdepth_grav = space_subdepth_grav_default;
 int space_maxsize = space_maxsize_default;
 #ifdef SWIFT_DEBUG_CHECKS
 int last_cell_id;

src/space.h

@@ -48,6 +48,7 @@ struct cosmology;
 #define space_subsize_self_hydro_default 32000
 #define space_subsize_pair_grav_default 256000000
 #define space_subsize_self_grav_default 32000
+#define space_subdepth_grav_default 2
 #define space_max_top_level_cells_default 12
 #define space_stretch 1.10f
 #define space_maxreldx 0.1f
@@ -62,6 +63,7 @@ extern int space_subsize_pair_hydro;
 extern int space_subsize_self_hydro;
 extern int space_subsize_pair_grav;
 extern int space_subsize_self_grav;
+extern int space_subdepth_grav;
 
 /**
  * @brief The space in which the cells and particles reside.