--- old/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp	Thu Jan 27 14:03:13 2011
+++ new/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp	Thu Jan 27 14:03:12 2011
@@ -112,7 +112,14 @@
   yg_cur_size = MAX2(yg_cur_size, yg_min_size);
 
   og_min_size = align_size_up(og_min_size, og_align);
-  og_max_size = align_size_up(og_max_size, og_align);
+  // Align old gen size down to preserve specified heap size.
+  assert(og_align == yg_align, "sanity");
+  size_t og_size = align_size_down(og_max_size, og_align);
+  if (og_size < og_min_size) {
+    og_max_size = og_min_size;
+  } else {
+    og_max_size = og_size;
+  }
   size_t og_cur_size =
     align_size_up(_collector_policy->old_gen_size(), og_align);
   og_cur_size = MAX2(og_cur_size, og_min_size);