--- old/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	2014-10-06 14:22:04.013729127 +0200
+++ new/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	2014-10-06 14:22:03.942727086 +0200
@@ -390,6 +390,8 @@
 }
 
 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
+  // The from card cache is not the memory that is actually committed. So we cannot
+  // take advantage of the zero_filled parameter.
   reset_from_card_cache(start_idx, num_regions);
 }
 
--- old/src/share/vm/gc_implementation/g1/g1SATBCardTableModRefBS.cpp	2014-10-06 14:22:04.297737292 +0200
+++ new/src/share/vm/gc_implementation/g1/g1SATBCardTableModRefBS.cpp	2014-10-06 14:22:04.233735452 +0200
@@ -126,6 +126,7 @@
 #endif
 
 void G1SATBCardTableLoggingModRefBSChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
+  // Default value for a clean card on the card table is -1. So we cannot take advantage of the zero_filled parameter.
   MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_idx), num_regions * HeapRegion::GrainWords);
   _card_table->clear(mr);
 }