src/hotspot/share/gc/shenandoah/heuristics/shenandoahPassiveHeuristics.hpp

@@ -25,12 +25,23 @@
  #ifndef SHARE_GC_SHENANDOAH_HEURISTICS_SHENANDOAHPASSIVEHEURISTICS_HPP
  #define SHARE_GC_SHENANDOAH_HEURISTICS_SHENANDOAHPASSIVEHEURISTICS_HPP
  
  #include "gc/shenandoah/heuristics/shenandoahHeuristics.hpp"
  
+ /*
+  * The passive heuristic is for use only with the passive mode. In
+  * the passive mode, Shenandoah only performs STW (i.e., degenerated)
+  * collections. All the barriers are disabled and there are no concurrent
+  * activities. Therefore, this heuristic _never_ triggers a cycle. It
+  * will select regions for evacuation based on ShenandoahEvacReserve,
+  * ShenandoahEvacWaste and ShenandoahGarbageThreshold. Note that it does
+  * not attempt to evacuate regions with more garbage.
+  */
  class ShenandoahPassiveHeuristics : public ShenandoahHeuristics {
  public:
+   ShenandoahPassiveHeuristics(ShenandoahSpaceInfo* space_info);
+ 
    virtual bool should_start_gc();
  
    virtual bool should_unload_classes();
  
    virtual bool should_degenerate_cycle();