src/hotspot/share/gc/cms/concurrentMarkSweepGeneration.cpp

@@ -690,10 +690,14 @@
 size_t
 ConcurrentMarkSweepGeneration::unsafe_max_alloc_nogc() const {
   return _cmsSpace->max_alloc_in_words() * HeapWordSize;
 }
 
+size_t ConcurrentMarkSweepGeneration::used_stable() const {
+  return cmsSpace()->used_stable();
+}
+
 size_t ConcurrentMarkSweepGeneration::max_available() const {
   return free() + _virtual_space.uncommitted_size();
 }
 
 bool ConcurrentMarkSweepGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const {

@@ -1521,10 +1525,12 @@
 void CMSCollector::compute_new_size() {
   assert_locked_or_safepoint(Heap_lock);
   FreelistLocker z(this);
   MetaspaceGC::compute_new_size();
   _cmsGen->compute_new_size_free_list();
+  // recalculate CMS used space after CMS collection
+  _cmsGen->cmsSpace()->recalculate_used_stable();
 }
 
 // A work method used by the foreground collector to do
 // a mark-sweep-compact.
 void CMSCollector::do_compaction_work(bool clear_all_soft_refs) {

@@ -2049,10 +2055,11 @@
 
 void ConcurrentMarkSweepGeneration::gc_prologue(bool full) {
 
   _capacity_at_prologue = capacity();
   _used_at_prologue = used();
+  _cmsSpace->recalculate_used_stable();
 
   // We enable promotion tracking so that card-scanning can recognize
   // which objects have been promoted during this GC and skip them.
   for (uint i = 0; i < ParallelGCThreads; i++) {
     _par_gc_thread_states[i]->promo.startTrackingPromotions();

@@ -2121,10 +2128,11 @@
   }
   // reset _eden_chunk_array so sampling starts afresh
   _eden_chunk_index = 0;
 
   size_t cms_used   = _cmsGen->cmsSpace()->used();
+  _cmsGen->cmsSpace()->recalculate_used_stable();
 
   // update performance counters - this uses a special version of
   // update_counters() that allows the utilization to be passed as a
   // parameter, avoiding multiple calls to used().
   //

@@ -2814,10 +2822,12 @@
     checkpointRootsInitialWork();
     // enable ("weak") refs discovery
     rp->enable_discovery();
     _collectorState = Marking;
   }
+
+  _cmsGen->cmsSpace()->recalculate_used_stable();
 }
 
 void CMSCollector::checkpointRootsInitialWork() {
   assert(SafepointSynchronize::is_at_safepoint(), "world should be stopped");
   assert(_collectorState == InitialMarking, "just checking");

@@ -4175,10 +4185,11 @@
     }
     FreelistLocker x(this);
     MutexLocker y(bitMapLock(),
                   Mutex::_no_safepoint_check_flag);
     checkpointRootsFinalWork();
+    _cmsGen->cmsSpace()->recalculate_used_stable();
   }
   verify_work_stacks_empty();
   verify_overflow_empty();
 }
 

@@ -5334,13 +5345,18 @@
     // We need all the free list locks to make the abstract state
     // transition from Sweeping to Resetting. See detailed note
     // further below.
     {
       CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock());
+      
       // Update heap occupancy information which is used as
       // input to soft ref clearing policy at the next gc.
       Universe::update_heap_info_at_gc();
+   
+      // recalculate CMS used space after CMS collection
+      _cmsGen->cmsSpace()->recalculate_used_stable();
+ 
       _collectorState = Resizing;
     }
   }
   verify_work_stacks_empty();
   verify_overflow_empty();

@@ -5425,10 +5441,11 @@
   bool current_is_young = CMSHeap::heap()->is_young_gen(current_generation);
   if (!full && current_is_young) {
     // Gather statistics on the young generation collection.
     collector()->stats().record_gc0_end(used());
   }
+  _cmsSpace->recalculate_used_stable();
 }
 
 void CMSCollector::sweepWork(ConcurrentMarkSweepGeneration* old_gen) {
   // We iterate over the space(s) underlying this generation,
   // checking the mark bit map to see if the bits corresponding