--- old/src/share/vm/gc_implementation/parallelScavenge/psMarkSweep.cpp	2013-11-13 10:43:40.000000000 -0800
+++ new/src/share/vm/gc_implementation/parallelScavenge/psMarkSweep.cpp	2013-11-13 10:43:40.000000000 -0800
@@ -280,6 +280,13 @@
       if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
           ((gc_cause != GCCause::_java_lang_system_gc) ||
             UseAdaptiveSizePolicyWithSystemGC)) {
+        // Swap the survivor spaces if from_space is empty
+        if (UseAdaptiveSizePolicyResizeYoungGenAtMajorCollection &&
+            young_gen->from_space()->is_empty()) {
+          young_gen->from_space()->clear(SpaceDecorator::Mangle);
+          young_gen->swap_spaces();
+        }
+
         // Calculate optimal free space amounts
         assert(young_gen->max_size() >
           young_gen->from_space()->capacity_in_bytes() +
@@ -318,12 +325,10 @@
 
         heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
 
-        // Don't resize the young generation at an major collection.  A
-        // desired young generation size may have been calculated but
-        // resizing the young generation complicates the code because the
-        // resizing of the old generation may have moved the boundary
-        // between the young generation and the old generation.  Let the
-        // young generation resizing happen at the minor collections.
+        if (UseAdaptiveSizePolicyResizeYoungGenAtMajorCollection) {
+          heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
+                                 size_policy->calculated_survivor_size_in_bytes());
+        }
       }
       if (PrintAdaptiveSizePolicy) {
         gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
--- old/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp	2013-11-13 10:43:41.000000000 -0800
+++ new/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp	2013-11-13 10:43:41.000000000 -0800
@@ -43,6 +43,7 @@
 #include "gc_implementation/shared/gcTrace.hpp"
 #include "gc_implementation/shared/gcTraceTime.hpp"
 #include "gc_implementation/shared/isGCActiveMark.hpp"
+#include "gc_implementation/shared/spaceDecorator.hpp"
 #include "gc_interface/gcCause.hpp"
 #include "memory/gcLocker.inline.hpp"
 #include "memory/referencePolicy.hpp"
@@ -2115,6 +2116,13 @@
       if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
           ((gc_cause != GCCause::_java_lang_system_gc) ||
             UseAdaptiveSizePolicyWithSystemGC)) {
+        // Swap the survivor spaces if from_space is empty
+        if (UseAdaptiveSizePolicyResizeYoungGenAtMajorCollection &&
+            young_gen->from_space()->is_empty()) {
+          young_gen->from_space()->clear(SpaceDecorator::Mangle);
+          young_gen->swap_spaces();
+        }
+
         // Calculate optimal free space amounts
         assert(young_gen->max_size() >
           young_gen->from_space()->capacity_in_bytes() +
@@ -2154,12 +2162,10 @@
         heap->resize_old_gen(
           size_policy->calculated_old_free_size_in_bytes());
 
-        // Don't resize the young generation at an major collection.  A
-        // desired young generation size may have been calculated but
-        // resizing the young generation complicates the code because the
-        // resizing of the old generation may have moved the boundary
-        // between the young generation and the old generation.  Let the
-        // young generation resizing happen at the minor collections.
+        if (UseAdaptiveSizePolicyResizeYoungGenAtMajorCollection) {
+          heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
+                                 size_policy->calculated_survivor_size_in_bytes());
+        }
       }
       if (PrintAdaptiveSizePolicy) {
         gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
--- old/src/share/vm/runtime/globals.hpp	2013-11-13 10:43:41.000000000 -0800
+++ new/src/share/vm/runtime/globals.hpp	2013-11-13 10:43:41.000000000 -0800
@@ -2068,6 +2068,10 @@
   product(bool, UseAdaptiveSizePolicyWithSystemGC, false,                   \
           "Include statistics from System.gc() for adaptive size policy")   \
                                                                             \
+  product(bool, UseAdaptiveSizePolicyResizeYoungGenAtMajorCollection, true, \
+          "Resize young generation at major collections"                    \
+          "for adaptive sizing policy")                                     \
+                                                                            \
   product(bool, UseAdaptiveGCBoundary, false,                               \
           "Allow young-old boundary to move")                               \
                                                                             \