diff -r 1f34864a0347 -r 4016de4e596b hotspot/src/share/vm/gc/g1/g1CollectedHeap.hpp
--- a/hotspot/src/share/vm/gc/g1/g1CollectedHeap.hpp	Tue Jul 05 21:24:24 2016 +0000
+++ b/hotspot/src/share/vm/gc/g1/g1CollectedHeap.hpp	Wed Jul 06 11:22:55 2016 +0200
@@ -778,13 +778,13 @@
   // The closure used to refine a single card.
   RefineCardTableEntryClosure* _refine_cte_cl;
 
-  // After a collection pause, make the regions in the CS into free
+  // After a collection pause, convert the regions in the collection set into free
   // regions.
-  void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
+  void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
 
   // Abandon the current collection set without recording policy
   // statistics or updating free lists.
-  void abandon_collection_set(HeapRegion* cs_head);
+  void abandon_collection_set(G1CollectionSet* collection_set);
 
   // The concurrent marker (and the thread it runs in.)
   G1ConcurrentMark* _cm;
@@ -930,16 +930,6 @@
   // discovery.
   G1CMIsAliveClosure _is_alive_closure_cm;
 
-  // Cache used by G1CollectedHeap::start_cset_region_for_worker().
-  HeapRegion** _worker_cset_start_region;
-
-  // Time stamp to validate the regions recorded in the cache
-  // used by G1CollectedHeap::start_cset_region_for_worker().
-  // The heap region entry for a given worker is valid iff
-  // the associated time stamp value matches the current value
-  // of G1CollectedHeap::_gc_time_stamp.
-  uint* _worker_cset_start_region_time_stamp;
-
   volatile bool _free_regions_coming;
 
 public:
@@ -1211,19 +1201,14 @@
                                HeapRegionClaimer* hrclaimer,
                                bool concurrent = false) const;
 
-  // Clear the cached cset start regions and (more importantly)
-  // the time stamps. Called when we reset the GC time stamp.
-  void clear_cset_start_regions();
-
-  // Given the id of a worker, obtain or calculate a suitable
-  // starting region for iterating over the current collection set.
-  HeapRegion* start_cset_region_for_worker(uint worker_i);
-
   // Iterate over the regions (if any) in the current collection set.
   void collection_set_iterate(HeapRegionClosure* blk);
 
-  // As above but starting from region r
-  void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk);
+  // Iterate over the regions (if any) in the current collection set. Starts the
+  // iteration over the entire collection set so that the start regions of a given
+  // worker id over the set active_workers are evenly spread across the set of
+  // collection set regions.
+  void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
 
   HeapRegion* next_compaction_region(const HeapRegion* from) const;