--- old/src/share/vm/gc_implementation/g1/heapRegion.cpp	2013-08-29 11:14:53.000000000 +0200
+++ new/src/share/vm/gc_implementation/g1/heapRegion.cpp	2013-08-29 11:14:53.000000000 +0200
@@ -26,6 +26,7 @@
 #include "code/nmethod.hpp"
 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
+#include "gc_implementation/g1/g1Log.hpp"
 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
 #include "gc_implementation/g1/heapRegion.inline.hpp"
 #include "gc_implementation/g1/heapRegionRemSet.hpp"
@@ -149,18 +150,11 @@
 // many regions in the heap (based on the min heap size).
 #define TARGET_REGION_NUMBER          2048
 
-void HeapRegion::setup_heap_region_size(uintx min_heap_size) {
-  // region_size in bytes
+void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
   uintx region_size = G1HeapRegionSize;
   if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
-    // We base the automatic calculation on the min heap size. This
-    // can be problematic if the spread between min and max is quite
-    // wide, imagine -Xms128m -Xmx32g. But, if we decided it based on
-    // the max size, the region size might be way too large for the
-    // min size. Either way, some users might have to set the region
-    // size manually for some -Xms / -Xmx combos.
-
-    region_size = MAX2(min_heap_size / TARGET_REGION_NUMBER,
+    size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
+    region_size = MAX2(average_heap_size / TARGET_REGION_NUMBER,
                        (uintx) MIN_REGION_SIZE);
   }
 
@@ -185,6 +179,10 @@
   // And recalculate the log.
   region_size_log = log2_long((jlong) region_size);
 
+  if (G1Log::fine()) {
+    gclog_or_tty->print_cr("G1 Heap region size: " SIZE_FORMAT "M", region_size / M);
+  }
+
   // Now, set up the globals.
   guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
   LogOfHRGrainBytes = region_size_log;