--- old/src/share/vm/gc_implementation/parallelScavenge/generationSizer.hpp	2013-09-19 22:40:47.000000000 +0200
+++ new/src/share/vm/gc_implementation/parallelScavenge/generationSizer.hpp	2013-09-19 22:40:47.000000000 +0200
@@ -31,11 +31,23 @@
 // TwoGenerationCollectorPolicy. Lets reuse it!
 
 class GenerationSizer : public TwoGenerationCollectorPolicy {
- public:
+private:
+
+  void trace_gen_sizes(const char* const str) {
+    if (TracePageSizes) {
+      tty->print_cr("%s:  " SIZE_FORMAT "," SIZE_FORMAT " "
+                    SIZE_FORMAT "," SIZE_FORMAT " "
+                    SIZE_FORMAT,
+                    str,
+                    _min_gen1_size / K, _max_gen1_size / K,
+                    _min_gen0_size / K, _max_gen0_size / K,
+                    _max_heap_byte_size / K);
+    }
+  }
+
+public:
   GenerationSizer() {
-    // Partial init only!
-    initialize_flags();
-    initialize_size_info();
+    initialize_all();
   }
 
   void initialize_flags() {
@@ -61,13 +73,30 @@
     }
   }
 
-  size_t min_young_gen_size() { return _min_gen0_size; }
-  size_t young_gen_size()     { return _initial_gen0_size; }
-  size_t max_young_gen_size() { return _max_gen0_size; }
-
-  size_t min_old_gen_size()   { return _min_gen1_size; }
-  size_t old_gen_size()       { return _initial_gen1_size; }
-  size_t max_old_gen_size()   { return _max_gen1_size; }
+  void initialize_size_info() {
+    TwoGenerationCollectorPolicy::initialize_size_info();
+
+    trace_gen_sizes("ps heap raw");
+    const size_t page_sz = os::page_size_for_region(_min_heap_byte_size,
+                                                    _max_heap_byte_size,
+                                                    8);
+
+    // Can a page size be something else than a power of two?
+    assert(is_power_of_2((intptr_t)page_sz), "must be a power of 2");
+    _min_alignment = round_to(page_sz, intra_heap_alignment());
+
+    // Update sizes to reflect the selected page size.
+    _min_gen0_size = align_size_up(_min_gen0_size, _min_alignment);
+    _initial_gen0_size = MAX2(align_size_up_(_initial_gen0_size, _min_alignment), _min_gen0_size);
+    _max_gen0_size = align_size_up(_max_gen0_size, _min_alignment);
+
+    // Align old gen size down to preserve specified heap size. Adjust all other values.
+    _max_gen1_size = max_heap_byte_size() - _max_gen0_size;
+    _min_gen1_size = MIN2(align_size_up_(_min_gen1_size, _min_alignment), _max_gen1_size);
+    _initial_gen1_size = MIN2(align_size_up_(_initial_gen1_size, _min_alignment), _max_gen1_size);
+
+    trace_gen_sizes("ps heap rnd");
+  }
 };
 
 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_GENERATIONSIZER_HPP