6631166: CMS: better heuristics when combatting fragmentation

Autonomic per-worker free block cache sizing, tunable coalition policies, fixes to per-size block statistics, retuned gain and bandwidth of some feedback loop filters to allow quicker reactivity to abrupt changes in ambient demand, and other heuristics to reduce fragmentation of the CMS old gen. Also tightened some assertions, including those related to locking.

Reviewed-by: jmasa

hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/binaryTreeDictionary.cpp

@@ -62,12 +62,13 @@ TreeList* TreeList::as_TreeList(TreeChunk* tc) {
   tl->link_head(tc);
   tl->link_tail(tc);
   tl->set_count(1);
-  tl->init_statistics();
+  tl->init_statistics(true /* split_birth */);
   tl->setParent(NULL);
   tl->setLeft(NULL);
   tl->setRight(NULL);
   return tl;
 }
+
 TreeList* TreeList::as_TreeList(HeapWord* addr, size_t size) {
   TreeChunk* tc = (TreeChunk*) addr;
   assert(size >= sizeof(TreeChunk), "Chunk is too small for a TreeChunk");
@@ -267,6 +268,31 @@ TreeChunk* TreeList::first_available() {
   return retTC;
 }
 
+// Returns the block with the largest heap address amongst
+// those in the list for this size; potentially slow and expensive,
+// use with caution!
+TreeChunk* TreeList::largest_address() {
+  guarantee(head() != NULL, "The head of the list cannot be NULL");
+  FreeChunk* fc = head()->next();
+  TreeChunk* retTC;
+  if (fc == NULL) {
+    retTC = head_as_TreeChunk();
+  } else {
+    // walk down the list and return the one with the highest
+    // heap address among chunks of this size.
+    FreeChunk* last = fc;
+    while (fc->next() != NULL) {
+      if ((HeapWord*)last < (HeapWord*)fc) {
+        last = fc;
+      }
+      fc = fc->next();
+    }
+    retTC = TreeChunk::as_TreeChunk(last);
+  }
+  assert(retTC->list() == this, "Wrong type of chunk.");
+  return retTC;
+}
+
 BinaryTreeDictionary::BinaryTreeDictionary(MemRegion mr, bool splay):
   _splay(splay)
 {
@@ -379,7 +405,7 @@ BinaryTreeDictionary::getChunkFromTree(size_t size, Dither dither, bool splay)
             break;
           }
           // The evm code reset the hint of the candidate as
-          // at an interrim point.  Why?  Seems like this leaves
+          // at an interim point.  Why?  Seems like this leaves
           // the hint pointing to a list that didn't work.
           // curTL->set_hint(hintTL->size());
         }
@@ -436,7 +462,7 @@ FreeChunk* BinaryTreeDictionary::findLargestDict() const {
   TreeList *curTL = root();
   if (curTL != NULL) {
     while(curTL->right() != NULL) curTL = curTL->right();
-    return curTL->first_available();
+    return curTL->largest_address();
   } else {
     return NULL;
   }
@@ -664,7 +690,7 @@ void BinaryTreeDictionary::insertChunkInTree(FreeChunk* fc) {
     }
   }
   TreeChunk* tc = TreeChunk::as_TreeChunk(fc);
-  // This chunk is being returned to the binary try.  It's embedded
+  // This chunk is being returned to the binary tree.  Its embedded
   // TreeList should be unused at this point.
   tc->initialize();
   if (curTL != NULL) {          // exact match
@@ -807,6 +833,8 @@ void BinaryTreeDictionary::dictCensusUpdate(size_t size, bool split, bool birth)
 }
 
 bool BinaryTreeDictionary::coalDictOverPopulated(size_t size) {
+  if (FLSAlwaysCoalesceLarge) return true;
+
   TreeList* list_of_size = findList(size);
   // None of requested size implies overpopulated.
   return list_of_size == NULL || list_of_size->coalDesired() <= 0 ||
@@ -854,17 +882,20 @@ class BeginSweepClosure : public AscendTreeCensusClosure {
   double _percentage;
   float _inter_sweep_current;
   float _inter_sweep_estimate;
+  float _intra_sweep_estimate;
 
  public:
   BeginSweepClosure(double p, float inter_sweep_current,
-                              float inter_sweep_estimate) :
+                              float inter_sweep_estimate,
+                              float intra_sweep_estimate) :
    _percentage(p),
    _inter_sweep_current(inter_sweep_current),
-   _inter_sweep_estimate(inter_sweep_estimate) { }
+   _inter_sweep_estimate(inter_sweep_estimate),
+   _intra_sweep_estimate(intra_sweep_estimate) { }
 
   void do_list(FreeList* fl) {
     double coalSurplusPercent = _percentage;
-    fl->compute_desired(_inter_sweep_current, _inter_sweep_estimate);
+    fl->compute_desired(_inter_sweep_current, _inter_sweep_estimate, _intra_sweep_estimate);
     fl->set_coalDesired((ssize_t)((double)fl->desired() * coalSurplusPercent));
     fl->set_beforeSweep(fl->count());
     fl->set_bfrSurp(fl->surplus());
@@ -939,9 +970,10 @@ FreeChunk* BinaryTreeDictionary::find_chunk_ends_at(HeapWord* target) const {
 }
 
 void BinaryTreeDictionary::beginSweepDictCensus(double coalSurplusPercent,
-  float inter_sweep_current, float inter_sweep_estimate) {
+  float inter_sweep_current, float inter_sweep_estimate, float intra_sweep_estimate) {
   BeginSweepClosure bsc(coalSurplusPercent, inter_sweep_current,
-                                            inter_sweep_estimate);
+                                            inter_sweep_estimate,
+                                            intra_sweep_estimate);
   bsc.do_tree(root());
 }
 
@@ -1077,13 +1109,13 @@ void BinaryTreeDictionary::reportStatistics() const {
 // Print census information - counts, births, deaths, etc.
 // for each list in the tree.  Also print some summary
 // information.
-class printTreeCensusClosure : public AscendTreeCensusClosure {
+class PrintTreeCensusClosure : public AscendTreeCensusClosure {
   int _print_line;
   size_t _totalFree;
   FreeList _total;
 
  public:
-  printTreeCensusClosure() {
+  PrintTreeCensusClosure() {
     _print_line = 0;
     _totalFree = 0;
   }
@@ -1113,7 +1145,7 @@ void BinaryTreeDictionary::printDictCensus(void) const {
 
   gclog_or_tty->print("\nBinaryTree\n");
   FreeList::print_labels_on(gclog_or_tty, "size");
-  printTreeCensusClosure ptc;
+  PrintTreeCensusClosure ptc;
   ptc.do_tree(root());
 
   FreeList* total = ptc.total();
@@ -1130,6 +1162,38 @@ void BinaryTreeDictionary::printDictCensus(void) const {
              /(total->desired() != 0 ? (double)total->desired() : 1.0));
 }
 
+class PrintFreeListsClosure : public AscendTreeCensusClosure {
+  outputStream* _st;
+  int _print_line;
+
+ public:
+  PrintFreeListsClosure(outputStream* st) {
+    _st = st;
+    _print_line = 0;
+  }
+  void do_list(FreeList* fl) {
+    if (++_print_line >= 40) {
+      FreeList::print_labels_on(_st, "size");
+      _print_line = 0;
+    }
+    fl->print_on(gclog_or_tty);
+    size_t sz = fl->size();
+    for (FreeChunk* fc = fl->head(); fc != NULL;
+         fc = fc->next()) {
+      _st->print_cr("\t[" PTR_FORMAT "," PTR_FORMAT ")  %s",
+                    fc, (HeapWord*)fc + sz,
+                    fc->cantCoalesce() ? "\t CC" : "");
+    }
+  }
+};
+
+void BinaryTreeDictionary::print_free_lists(outputStream* st) const {
+
+  FreeList::print_labels_on(st, "size");
+  PrintFreeListsClosure pflc(st);
+  pflc.do_tree(root());
+}
+
 // Verify the following tree invariants:
 // . _root has no parent
 // . parent and child point to each other