6711316: Open source the Garbage-First garbage collector

First mercurial integration of the code for the Garbage-First garbage collector.

Reviewed-by: apetrusenko, iveresov, jmasa, sgoldman, tonyp, ysr

hotspot/src/share/vm/gc_implementation/g1/collectionSetChooser.cpp

@@ -0,0 +1,409 @@
+/*
+ * Copyright 2001-2007 Sun Microsystems, Inc.  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.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+# include "incls/_precompiled.incl"
+# include "incls/_collectionSetChooser.cpp.incl"
+
+CSetChooserCache::CSetChooserCache() {
+  for (int i = 0; i < CacheLength; ++i)
+    _cache[i] = NULL;
+  clear();
+}
+
+void CSetChooserCache::clear() {
+  _occupancy = 0;
+  _first = 0;
+  for (int i = 0; i < CacheLength; ++i) {
+    HeapRegion *hr = _cache[i];
+    if (hr != NULL)
+      hr->set_sort_index(-1);
+    _cache[i] = NULL;
+  }
+}
+
+#ifndef PRODUCT
+bool CSetChooserCache::verify() {
+  int index = _first;
+  HeapRegion *prev = NULL;
+  for (int i = 0; i < _occupancy; ++i) {
+    guarantee(_cache[index] != NULL, "cache entry should not be empty");
+    HeapRegion *hr = _cache[index];
+    guarantee(!hr->is_young(), "should not be young!");
+    if (prev != NULL) {
+      guarantee(prev->gc_efficiency() >= hr->gc_efficiency(),
+                "cache should be correctly ordered");
+    }
+    guarantee(hr->sort_index() == get_sort_index(index),
+              "sort index should be correct");
+    index = trim_index(index + 1);
+    prev = hr;
+  }
+
+  for (int i = 0; i < (CacheLength - _occupancy); ++i) {
+    guarantee(_cache[index] == NULL, "cache entry should be empty");
+    index = trim_index(index + 1);
+  }
+
+  guarantee(index == _first, "we should have reached where we started from");
+  return true;
+}
+#endif // PRODUCT
+
+void CSetChooserCache::insert(HeapRegion *hr) {
+  assert(!is_full(), "cache should not be empty");
+  hr->calc_gc_efficiency();
+
+  int empty_index;
+  if (_occupancy == 0) {
+    empty_index = _first;
+  } else {
+    empty_index = trim_index(_first + _occupancy);
+    assert(_cache[empty_index] == NULL, "last slot should be empty");
+    int last_index = trim_index(empty_index - 1);
+    HeapRegion *last = _cache[last_index];
+    assert(last != NULL,"as the cache is not empty, last should not be empty");
+    while (empty_index != _first &&
+           last->gc_efficiency() < hr->gc_efficiency()) {
+      _cache[empty_index] = last;
+      last->set_sort_index(get_sort_index(empty_index));
+      empty_index = last_index;
+      last_index = trim_index(last_index - 1);
+      last = _cache[last_index];
+    }
+  }
+  _cache[empty_index] = hr;
+  hr->set_sort_index(get_sort_index(empty_index));
+
+  ++_occupancy;
+  assert(verify(), "cache should be consistent");
+}
+
+HeapRegion *CSetChooserCache::remove_first() {
+  if (_occupancy > 0) {
+    assert(_cache[_first] != NULL, "cache should have at least one region");
+    HeapRegion *ret = _cache[_first];
+    _cache[_first] = NULL;
+    ret->set_sort_index(-1);
+    --_occupancy;
+    _first = trim_index(_first + 1);
+    assert(verify(), "cache should be consistent");
+    return ret;
+  } else {
+    return NULL;
+  }
+}
+
+// this is a bit expensive... but we expect that it should not be called
+// to often.
+void CSetChooserCache::remove(HeapRegion *hr) {
+  assert(_occupancy > 0, "cache should not be empty");
+  assert(hr->sort_index() < -1, "should already be in the cache");
+  int index = get_index(hr->sort_index());
+  assert(_cache[index] == hr, "index should be correct");
+  int next_index = trim_index(index + 1);
+  int last_index = trim_index(_first + _occupancy - 1);
+  while (index != last_index) {
+    assert(_cache[next_index] != NULL, "should not be null");
+    _cache[index] = _cache[next_index];
+    _cache[index]->set_sort_index(get_sort_index(index));
+
+    index = next_index;
+    next_index = trim_index(next_index+1);
+  }
+  assert(index == last_index, "should have reached the last one");
+  _cache[index] = NULL;
+  hr->set_sort_index(-1);
+  --_occupancy;
+  assert(verify(), "cache should be consistent");
+}
+
+static inline int orderRegions(HeapRegion* hr1, HeapRegion* hr2) {
+  if (hr1 == NULL) {
+    if (hr2 == NULL) return 0;
+    else return 1;
+  } else if (hr2 == NULL) {
+    return -1;
+  }
+  if (hr2->gc_efficiency() < hr1->gc_efficiency()) return -1;
+  else if (hr1->gc_efficiency() < hr2->gc_efficiency()) return 1;
+  else return 0;
+}
+
+static int orderRegions(HeapRegion** hr1p, HeapRegion** hr2p) {
+  return orderRegions(*hr1p, *hr2p);
+}
+
+CollectionSetChooser::CollectionSetChooser() :
+  // The line below is the worst bit of C++ hackery I've ever written
+  // (Detlefs, 11/23).  You should think of it as equivalent to
+  // "_regions(100, true)": initialize the growable array and inform it
+  // that it should allocate its elem array(s) on the C heap.  The first
+  // argument, however, is actually a comma expression (new-expr, 100).
+  // The purpose of the new_expr is to inform the growable array that it
+  // is *already* allocated on the C heap: it uses the placement syntax to
+  // keep it from actually doing any allocation.
+  _markedRegions((ResourceObj::operator new (sizeof(GrowableArray<HeapRegion*>),
+                                             (void*)&_markedRegions,
+                                             ResourceObj::C_HEAP),
+                  100),
+                 true),
+  _curMarkedIndex(0),
+  _numMarkedRegions(0),
+  _unmarked_age_1_returned_as_new(false),
+  _first_par_unreserved_idx(0)
+{}
+
+
+
+#ifndef PRODUCT
+bool CollectionSetChooser::verify() {
+  int index = 0;
+  guarantee(_curMarkedIndex <= _numMarkedRegions,
+            "_curMarkedIndex should be within bounds");
+  while (index < _curMarkedIndex) {
+    guarantee(_markedRegions.at(index++) == NULL,
+              "all entries before _curMarkedIndex should be NULL");
+  }
+  HeapRegion *prev = NULL;
+  while (index < _numMarkedRegions) {
+    HeapRegion *curr = _markedRegions.at(index++);
+    if (curr != NULL) {
+      int si = curr->sort_index();
+      guarantee(!curr->is_young(), "should not be young!");
+      guarantee(si > -1 && si == (index-1), "sort index invariant");
+      if (prev != NULL) {
+        guarantee(orderRegions(prev, curr) != 1, "regions should be sorted");
+      }
+      prev = curr;
+    }
+  }
+  return _cache.verify();
+}
+#endif
+
+bool
+CollectionSetChooser::addRegionToCache() {
+  assert(!_cache.is_full(), "cache should not be full");
+
+  HeapRegion *hr = NULL;
+  while (hr == NULL && _curMarkedIndex < _numMarkedRegions) {
+    hr = _markedRegions.at(_curMarkedIndex++);
+  }
+  if (hr == NULL)
+    return false;
+  assert(!hr->is_young(), "should not be young!");
+  assert(hr->sort_index() == _curMarkedIndex-1, "sort_index invariant");
+  _markedRegions.at_put(hr->sort_index(), NULL);
+  _cache.insert(hr);
+  assert(!_cache.is_empty(), "cache should not be empty");
+  assert(verify(), "cache should be consistent");
+  return false;
+}
+
+void
+CollectionSetChooser::fillCache() {
+  while (!_cache.is_full() && addRegionToCache()) {
+  }
+}
+
+void
+CollectionSetChooser::sortMarkedHeapRegions() {
+  guarantee(_cache.is_empty(), "cache should be empty");
+  // First trim any unused portion of the top in the parallel case.
+  if (_first_par_unreserved_idx > 0) {
+    if (G1PrintParCleanupStats) {
+      gclog_or_tty->print("     Truncating _markedRegions from %d to %d.\n",
+                          _markedRegions.length(), _first_par_unreserved_idx);
+    }
+    assert(_first_par_unreserved_idx <= _markedRegions.length(),
+           "Or we didn't reserved enough length");
+    _markedRegions.trunc_to(_first_par_unreserved_idx);
+  }
+  _markedRegions.sort(orderRegions);
+  assert(_numMarkedRegions <= _markedRegions.length(), "Requirement");
+  assert(_numMarkedRegions == 0
+         || _markedRegions.at(_numMarkedRegions-1) != NULL,
+         "Testing _numMarkedRegions");
+  assert(_numMarkedRegions == _markedRegions.length()
+         || _markedRegions.at(_numMarkedRegions) == NULL,
+         "Testing _numMarkedRegions");
+  if (G1PrintParCleanupStats) {
+    gclog_or_tty->print_cr("     Sorted %d marked regions.", _numMarkedRegions);
+  }
+  for (int i = 0; i < _numMarkedRegions; i++) {
+    assert(_markedRegions.at(i) != NULL, "Should be true by sorting!");
+    _markedRegions.at(i)->set_sort_index(i);
+    if (G1PrintRegionLivenessInfo > 0) {
+      if (i == 0) gclog_or_tty->print_cr("Sorted marked regions:");
+      if (i < G1PrintRegionLivenessInfo ||
+          (_numMarkedRegions-i) < G1PrintRegionLivenessInfo) {
+        HeapRegion* hr = _markedRegions.at(i);
+        size_t u = hr->used();
+        gclog_or_tty->print_cr("  Region %d: %d used, %d max live, %5.2f%%.",
+                      i, u, hr->max_live_bytes(),
+                      100.0*(float)hr->max_live_bytes()/(float)u);
+      }
+    }
+  }
+  if (G1PolicyVerbose > 1)
+    printSortedHeapRegions();
+  assert(verify(), "should now be sorted");
+}
+
+void
+printHeapRegion(HeapRegion *hr) {
+  if (hr->isHumongous())
+    gclog_or_tty->print("H: ");
+  if (hr->in_collection_set())
+    gclog_or_tty->print("CS: ");
+  if (hr->popular())
+    gclog_or_tty->print("pop: ");
+  gclog_or_tty->print_cr("Region " PTR_FORMAT " (%s%s) "
+                         "[" PTR_FORMAT ", " PTR_FORMAT"] "
+                         "Used: " SIZE_FORMAT "K, garbage: " SIZE_FORMAT "K.",
+                         hr, hr->is_young() ? "Y " : "  ",
+                         hr->is_marked()? "M1" : "M0",
+                         hr->bottom(), hr->end(),
+                         hr->used()/K, hr->garbage_bytes()/K);
+}
+
+void
+CollectionSetChooser::addMarkedHeapRegion(HeapRegion* hr) {
+  assert(!hr->isHumongous(),
+         "Humongous regions shouldn't be added to the collection set");
+  assert(!hr->is_young(), "should not be young!");
+  _markedRegions.append(hr);
+  _numMarkedRegions++;
+  hr->calc_gc_efficiency();
+}
+
+void
+CollectionSetChooser::
+prepareForAddMarkedHeapRegionsPar(size_t n_regions, size_t chunkSize) {
+  _first_par_unreserved_idx = 0;
+  size_t max_waste = ParallelGCThreads * chunkSize;
+  // it should be aligned with respect to chunkSize
+  size_t aligned_n_regions =
+                     (n_regions + (chunkSize - 1)) / chunkSize * chunkSize;
+  assert( aligned_n_regions % chunkSize == 0, "should be aligned" );
+  _markedRegions.at_put_grow((int)(aligned_n_regions + max_waste - 1), NULL);
+}
+
+jint
+CollectionSetChooser::getParMarkedHeapRegionChunk(jint n_regions) {
+  jint res = Atomic::add(n_regions, &_first_par_unreserved_idx);
+  assert(_markedRegions.length() > res + n_regions - 1,
+         "Should already have been expanded");
+  return res - n_regions;
+}
+
+void
+CollectionSetChooser::setMarkedHeapRegion(jint index, HeapRegion* hr) {
+  assert(_markedRegions.at(index) == NULL, "precondition");
+  assert(!hr->is_young(), "should not be young!");
+  _markedRegions.at_put(index, hr);
+  hr->calc_gc_efficiency();
+}
+
+void
+CollectionSetChooser::incNumMarkedHeapRegions(jint inc_by) {
+  (void)Atomic::add(inc_by, &_numMarkedRegions);
+}
+
+void
+CollectionSetChooser::clearMarkedHeapRegions(){
+  for (int i = 0; i < _markedRegions.length(); i++) {
+    HeapRegion* r =   _markedRegions.at(i);
+    if (r != NULL) r->set_sort_index(-1);
+  }
+  _markedRegions.clear();
+  _curMarkedIndex = 0;
+  _numMarkedRegions = 0;
+  _cache.clear();
+};
+
+void
+CollectionSetChooser::updateAfterFullCollection() {
+  G1CollectedHeap* g1h = G1CollectedHeap::heap();
+  clearMarkedHeapRegions();
+}
+
+void
+CollectionSetChooser::printSortedHeapRegions() {
+  gclog_or_tty->print_cr("Printing %d Heap Regions sorted by amount of known garbage",
+                _numMarkedRegions);
+  for (int i = 0; i < _markedRegions.length(); i++) {
+    printHeapRegion(_markedRegions.at(i));
+  }
+  gclog_or_tty->print_cr("Done sorted heap region print");
+}
+
+void CollectionSetChooser::removeRegion(HeapRegion *hr) {
+  int si = hr->sort_index();
+  assert(si == -1 || hr->is_marked(), "Sort index not valid.");
+  if (si > -1) {
+    assert(_markedRegions.at(si) == hr, "Sort index not valid." );
+    _markedRegions.at_put(si, NULL);
+  } else if (si < -1) {
+    assert(_cache.region_in_cache(hr), "should be in the cache");
+    _cache.remove(hr);
+    assert(hr->sort_index() == -1, "sort index invariant");
+  }
+  hr->set_sort_index(-1);
+}
+
+// if time_remaining < 0.0, then this method should try to return
+// a region, whether it fits within the remaining time or not
+HeapRegion*
+CollectionSetChooser::getNextMarkedRegion(double time_remaining,
+                                          double avg_prediction) {
+  G1CollectedHeap* g1h = G1CollectedHeap::heap();
+  G1CollectorPolicy* g1p = g1h->g1_policy();
+  fillCache();
+  if (_cache.is_empty()) {
+    assert(_curMarkedIndex == _numMarkedRegions,
+           "if cache is empty, list should also be empty");
+    return NULL;
+  }
+
+  HeapRegion *hr = _cache.get_first();
+  assert(hr != NULL, "if cache not empty, first entry should be non-null");
+  double predicted_time = g1h->predict_region_elapsed_time_ms(hr, false);
+
+  if (g1p->adaptive_young_list_length()) {
+    if (time_remaining - predicted_time < 0.0) {
+      g1h->check_if_region_is_too_expensive(predicted_time);
+      return NULL;
+    }
+  } else {
+    if (predicted_time > 2.0 * avg_prediction) {
+      return NULL;
+    }
+  }
+
+  HeapRegion *hr2 = _cache.remove_first();
+  assert(hr == hr2, "cache contents should not have changed");
+
+  return hr;
+}