Carpet: Add facility to switch off synchronsing during time evolution

Add parameter sync_during_time_integration.  This parameters disables
synchronisation during time integration, similar to the way in which
prolongation is disabled.  This can potentially reduce communication
overhead.

darcs-hash:20061206163017-dae7b-953a43e45537fcac6acb2436cbcba3a1b75ee938.gz

1 files changed, 30 insertions, 24 deletions

diff --git a/Carpet/Carpet/src/Comm.cc b/Carpet/Carpet/src/Comm.cc
index 284484eb2..0ad0e6faf 100644
--- a/Carpet/Carpet/src/Comm.cc
+++ b/Carpet/Carpet/src/Comm.cc
@@ -127,35 +127,41 @@ namespace Carpet {
     }
 
     if (goodgroups.size() > 0) {
-      // prolongate boundaries
-      if (reflevel > 0) {
-        if (do_prolongate) {
-          bool local_do_prolongate;
-          if (use_tapered_grids) {
-            // TODO: Check iteration number instead
-            CCTK_REAL mytime;
-            CCTK_REAL parenttime;
-            if (map == -1) {
-              mytime = vtt.at(0)->time (0, reflevel, mglevel);
-              parenttime = vtt.at(0)->time (0, reflevel - 1, mglevel);
-            } else {
-              mytime = vtt.at(map)->time (0, reflevel, mglevel);
-              parenttime = vtt.at(map)->time (0, reflevel - 1, mglevel);
-            }
-            bool const in_sync =
-              abs (mytime - parenttime) < 1.0e-10 * abs (delta_time);
-            local_do_prolongate = in_sync;
+      
+      bool local_do_prolongate;
+      if (do_prolongate) {
+        if (use_tapered_grids) {
+          // TODO: Check iteration number instead
+          CCTK_REAL mytime;
+          CCTK_REAL parenttime;
+          if (map == -1) {
+            mytime = vtt.at(0)->time (0, reflevel, mglevel);
+            parenttime = vtt.at(0)->time (0, reflevel - 1, mglevel);
           } else {
-            local_do_prolongate = true;
-          }
-          if (local_do_prolongate) {
-            ProlongateGroupBoundaries (cctkGH, cctk_initial_time, goodgroups);
+            mytime = vtt.at(map)->time (0, reflevel, mglevel);
+            parenttime = vtt.at(map)->time (0, reflevel - 1, mglevel);
           }
+          bool const in_sync =
+            abs (mytime - parenttime) < 1.0e-10 * abs (delta_time);
+          local_do_prolongate = in_sync;
+        } else {
+          local_do_prolongate = true;
         }
+      } else {
+        local_do_prolongate = false;
       }
-
+      
+      // prolongate boundaries
+      if (local_do_prolongate) {
+        if (reflevel > 0) {
+          ProlongateGroupBoundaries (cctkGH, cctk_initial_time, goodgroups);
+        }
+      }
+      
       // synchronise ghostzones
-      SyncGroups (cctkGH, goodgroups);
+      if (sync_during_time_integration or local_do_prolongate) {
+        SyncGroups (cctkGH, goodgroups);
+      }
     }
 
     return retval;