src/share/vm/gc_implementation/g1/heapRegionRemSet.cpp

rev 5920 : 8035406: Improve data structure for Code Cache remembered sets
Summary: Change the code cache remembered sets data structure from a GrowableArray to a chunked list of nmethods. This makes the data structure more amenable to parallelization, and decreases freeing time.
Reviewed-by:

@@ -1,7 +1,7 @@
 /*
- * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.

@@ -259,12 +259,11 @@
 size_t OtherRegionsTable::_fine_eviction_stride = 0;
 size_t OtherRegionsTable::_fine_eviction_sample_size = 0;
 
 OtherRegionsTable::OtherRegionsTable(HeapRegion* hr) :
   _g1h(G1CollectedHeap::heap()),
-  _m(Mutex::leaf, "An OtherRegionsTable lock", true),
-  _hr(hr),
+  _hr(hr), _m(NULL),
   _coarse_map(G1CollectedHeap::heap()->max_regions(),
               false /* in-resource-area */),
   _fine_grain_regions(NULL),
   _first_all_fine_prts(NULL), _last_all_fine_prts(NULL),
   _n_fine_entries(0), _n_coarse_entries(0),

@@ -440,11 +439,11 @@
 
   // Otherwise find a per-region table to add it to.
   size_t ind = from_hrs_ind & _mod_max_fine_entries_mask;
   PerRegionTable* prt = find_region_table(ind, from_hr);
   if (prt == NULL) {
-    MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
+    MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
     // Confirm that it's really not there...
     prt = find_region_table(ind, from_hr);
     if (prt == NULL) {
 
       uintptr_t from_hr_bot_card_index =

@@ -542,11 +541,11 @@
 }
 
 jint OtherRegionsTable::_n_coarsenings = 0;
 
 PerRegionTable* OtherRegionsTable::delete_region_table() {
-  assert(_m.owned_by_self(), "Precondition");
+  assert(_m->owned_by_self(), "Precondition");
   assert(_n_fine_entries == _max_fine_entries, "Precondition");
   PerRegionTable* max = NULL;
   jint max_occ = 0;
   PerRegionTable** max_prev;
   size_t max_ind;

@@ -674,12 +673,10 @@
   clear_fcc();
 }
 
 
 size_t OtherRegionsTable::occupied() const {
-  // Cast away const in this case.
-  MutexLockerEx x((Mutex*)&_m, Mutex::_no_safepoint_check_flag);
   size_t sum = occ_fine();
   sum += occ_sparse();
   sum += occ_coarse();
   return sum;
 }

@@ -705,12 +702,10 @@
 size_t OtherRegionsTable::occ_sparse() const {
   return _sparse_table.occupied();
 }
 
 size_t OtherRegionsTable::mem_size() const {
-  // Cast away const in this case.
-  MutexLockerEx x((Mutex*)&_m, Mutex::_no_safepoint_check_flag);
   size_t sum = 0;
   // all PRTs are of the same size so it is sufficient to query only one of them.
   if (_first_all_fine_prts != NULL) {
     assert(_last_all_fine_prts != NULL &&
       _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant");

@@ -737,11 +732,10 @@
     _from_card_cache[i][hrs_idx] = -1;
   }
 }
 
 void OtherRegionsTable::clear() {
-  MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
   // if there are no entries, skip this step
   if (_first_all_fine_prts != NULL) {
     guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
     PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
     memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));

@@ -757,11 +751,11 @@
 
   clear_fcc();
 }
 
 void OtherRegionsTable::clear_incoming_entry(HeapRegion* from_hr) {
-  MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
+  MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
   size_t hrs_ind = (size_t) from_hr->hrs_index();
   size_t ind = hrs_ind & _mod_max_fine_entries_mask;
   if (del_single_region_table(ind, from_hr)) {
     assert(!_coarse_map.at(hrs_ind), "Inv");
   } else {

@@ -803,11 +797,11 @@
   }
 }
 
 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
   // Cast away const in this case.
-  MutexLockerEx x((Mutex*)&_m, Mutex::_no_safepoint_check_flag);
+  MutexLockerEx x((Mutex*)_m, Mutex::_no_safepoint_check_flag);
   return contains_reference_locked(from);
 }
 
 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
   HeapRegion* hr = _g1h->heap_region_containing_raw(from);

@@ -848,12 +842,23 @@
   return (int)MAX2(DirtyCardQueueSet::num_par_ids() + ConcurrentG1Refine::thread_num(), ParallelGCThreads);
 }
 
 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetSharedArray* bosa,
                                    HeapRegion* hr)
-  : _bosa(bosa), _strong_code_roots_list(NULL), _other_regions(hr) {
+  : _bosa(bosa), _m(NULL),
+    _code_roots(), _other_regions(hr) {
   reset_for_par_iteration();
+  const int max_name_length = 100;
+  char name[max_name_length];
+  jio_snprintf(name, max_name_length, "HeapRegionRemSet lock #"UINT32_FORMAT, hr->hrs_index());
+  _m = new Mutex(Mutex::leaf, name, true);
+
+  _other_regions.set_mutex(_m);
+}
+
+HeapRegionRemSet::~HeapRegionRemSet() {
+  delete _m;
 }
 
 void HeapRegionRemSet::setup_remset_size() {
   // Setup sparse and fine-grain tables sizes.
   // table_size = base * (log(region_size / 1M) + 1)

@@ -881,11 +886,11 @@
 bool HeapRegionRemSet::iter_is_complete() {
   return _iter_state == Complete;
 }
 
 #ifndef PRODUCT
-void HeapRegionRemSet::print() const {
+void HeapRegionRemSet::print() {
   HeapRegionRemSetIterator iter(this);
   size_t card_index;
   while (iter.has_next(card_index)) {
     HeapWord* card_start =
       G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index);

@@ -907,18 +912,18 @@
 void HeapRegionRemSet::cleanup() {
   SparsePRT::cleanup_all();
 }
 
 void HeapRegionRemSet::clear() {
-  if (_strong_code_roots_list != NULL) {
-    delete _strong_code_roots_list;
-  }
-  _strong_code_roots_list = new (ResourceObj::C_HEAP, mtGC)
-                                GrowableArray<nmethod*>(10, 0, NULL, true);
+  MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
+  clear_locked();
+}
 
+void HeapRegionRemSet::clear_locked() {
+  _code_roots.clear();
   _other_regions.clear();
-  assert(occupied() == 0, "Should be clear.");
+  assert(occupied_locked() == 0, "Should be clear.");
   reset_for_par_iteration();
 }
 
 void HeapRegionRemSet::reset_for_par_iteration() {
   _iter_state = Unclaimed;

@@ -935,26 +940,18 @@
 
 // Code roots support
 
 void HeapRegionRemSet::add_strong_code_root(nmethod* nm) {
   assert(nm != NULL, "sanity");
-  // Search for the code blob from the RHS to avoid
-  // duplicate entries as much as possible
-  if (_strong_code_roots_list->find_from_end(nm) < 0) {
-    // Code blob isn't already in the list
-    _strong_code_roots_list->push(nm);
-  }
+  _code_roots.add(nm);
 }
 
 void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) {
   assert(nm != NULL, "sanity");
-  int idx = _strong_code_roots_list->find(nm);
-  if (idx >= 0) {
-    _strong_code_roots_list->remove_at(idx);
-  }
+  _code_roots.remove(nm);
   // Check that there were no duplicates
-  guarantee(_strong_code_roots_list->find(nm) < 0, "duplicate entry found");
+  guarantee(!_code_roots.contains(nm), "duplicate entry found");
 }
 
 class NMethodMigrationOopClosure : public OopClosure {
   G1CollectedHeap* _g1h;
   HeapRegion* _from;

@@ -1012,12 +1009,12 @@
 
   // List of code blobs to retain for this region
   GrowableArray<nmethod*> to_be_retained(10);
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 
-  while (_strong_code_roots_list->is_nonempty()) {
-    nmethod *nm = _strong_code_roots_list->pop();
+  while (!_code_roots.is_empty()) {
+    nmethod *nm = _code_roots.pop();
     if (nm != NULL) {
       NMethodMigrationOopClosure oop_cl(g1h, hr(), nm);
       nm->oops_do(&oop_cl);
       if (oop_cl.retain()) {
         to_be_retained.push(nm);

@@ -1036,24 +1033,20 @@
     add_strong_code_root(nm);
   }
 }
 
 void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const {
-  for (int i = 0; i < _strong_code_roots_list->length(); i += 1) {
-    nmethod* nm = _strong_code_roots_list->at(i);
-    blk->do_code_blob(nm);
-  }
+  _code_roots.nmethods_do(blk);
 }
 
 size_t HeapRegionRemSet::strong_code_roots_mem_size() {
-  return sizeof(GrowableArray<nmethod*>) +
-         _strong_code_roots_list->max_length() * sizeof(nmethod*);
+  return _code_roots.mem_size();
 }
 
 //-------------------- Iteration --------------------
 
-HeapRegionRemSetIterator:: HeapRegionRemSetIterator(const HeapRegionRemSet* hrrs) :
+HeapRegionRemSetIterator:: HeapRegionRemSetIterator(HeapRegionRemSet* hrrs) :
   _hrrs(hrrs),
   _g1h(G1CollectedHeap::heap()),
   _coarse_map(&hrrs->_other_regions._coarse_map),
   _fine_grain_regions(hrrs->_other_regions._fine_grain_regions),
   _bosa(hrrs->bosa()),