jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/collectionSetChooser.hpp@2ace1c4ee8da (annotated)

src/share/vm/gc_implementation/g1/collectionSetChooser.hpp@2ace1c4ee8da (annotated)

src/share/vm/gc_implementation/g1/collectionSetChooser.hpp

Tue, 10 Jan 2012 18:58:13 -0500

author: tonyp
date: Tue, 10 Jan 2012 18:58:13 -0500
changeset 3416: 2ace1c4ee8da
parent 3185: b9390528617c
child 3539: a9647476d1a4
permissions: -rw-r--r--

6888336: G1: avoid explicitly marking and pushing objects in survivor spaces
Summary: This change simplifies the interaction between GC and concurrent marking. By disabling survivor spaces during the initial-mark pause we don't need to propagate marks of objects we copy during each GC (since we never need to copy an explicitly marked object).
Reviewed-by: johnc, brutisso

 /*
  * Copyright (c) 2001, 2011, 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.
  *
  * 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_COLLECTIONSETCHOOSER_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_G1_COLLECTIONSETCHOOSER_HPP
 #include "gc_implementation/g1/heapRegion.hpp"
 #include "utilities/growableArray.hpp"
 // We need to sort heap regions by collection desirability.
 // This sorting is currently done in two "stages". An initial sort is
 // done following a cleanup pause as soon as all of the marked but
 // non-empty regions have been identified and the completely empty
 // ones reclaimed.
 // This gives us a global sort on a GC efficiency metric
 // based on predictive data available at that time. However,
 // any of these regions that are collected will only be collected
 // during a future GC pause, by which time it is possible that newer
 // data might allow us to revise and/or refine the earlier
 // pause predictions, leading to changes in expected gc efficiency
 // order. To somewhat mitigate this obsolescence, more so in the
 // case of regions towards the end of the list, which will be
 // picked later, these pre-sorted regions from the _markedRegions
 // array are not used as is, but a small prefix thereof is
 // insertion-sorted again into a small cache, based on more
 // recent remembered set information. Regions are then drawn
 // from this cache to construct the collection set at each
 // incremental GC.
 // This scheme and/or its implementation may be subject to
 // revision in the future.
 class CSetChooserCache VALUE_OBJ_CLASS_SPEC {
 private:
   enum {
     CacheLength = 16
   } PrivateConstants;
   HeapRegion*  _cache[CacheLength];
   int          _occupancy; // number of regions in cache
   int          _first;     // (index of) "first" region in the cache
   // adding CacheLength to deal with negative values
   inline int trim_index(int index) {
     return (index + CacheLength) % CacheLength;
   }
   inline int get_sort_index(int index) {
     return -index-2;
   }
   inline int get_index(int sort_index) {
     return -sort_index-2;
   }
 public:
   CSetChooserCache(void);
   inline int occupancy(void) { return _occupancy; }
   inline bool is_full()      { return _occupancy == CacheLength; }
   inline bool is_empty()     { return _occupancy == 0; }
   void clear(void);
   void insert(HeapRegion *hr);
   HeapRegion *remove_first(void);
   inline HeapRegion *get_first(void) {
     return _cache[_first];
   }
 #ifndef PRODUCT
   bool verify (void);
   bool region_in_cache(HeapRegion *hr) {
     int sort_index = hr->sort_index();
     if (sort_index < -1) {
       int index = get_index(sort_index);
       guarantee(index < CacheLength, "should be within bounds");
       return _cache[index] == hr;
     } else
       return 0;
   }
 #endif // PRODUCT
 };
 class CollectionSetChooser: public CHeapObj {
   GrowableArray<HeapRegion*> _markedRegions;
   int _curMarkedIndex;
   int _numMarkedRegions;
   CSetChooserCache _cache;
   // True iff last collection pause ran of out new "age 0" regions, and
   // returned an "age 1" region.
   bool _unmarked_age_1_returned_as_new;
   jint _first_par_unreserved_idx;
 public:
   HeapRegion* getNextMarkedRegion(double time_so_far, double avg_prediction);
   CollectionSetChooser();
   void sortMarkedHeapRegions();
   void fillCache();
   void addMarkedHeapRegion(HeapRegion *hr);
   // Must be called before calls to getParMarkedHeapRegionChunk.
   // "n_regions" is the number of regions, "chunkSize" the chunk size.
   void prepareForAddMarkedHeapRegionsPar(size_t n_regions, size_t chunkSize);
   // Returns the first index in a contiguous chunk of "n_regions" indexes
   // that the calling thread has reserved.  These must be set by the
   // calling thread using "setMarkedHeapRegion" (to NULL if necessary).
   jint getParMarkedHeapRegionChunk(jint n_regions);
   // Set the marked array entry at index to hr.  Careful to claim the index
   // first if in parallel.
   void setMarkedHeapRegion(jint index, HeapRegion* hr);
   // Atomically increment the number of claimed regions by "inc_by".
   void incNumMarkedHeapRegions(jint inc_by);
   void clearMarkedHeapRegions();
   void updateAfterFullCollection();
   bool unmarked_age_1_returned_as_new() { return _unmarked_age_1_returned_as_new; }
   // Returns true if the used portion of "_markedRegions" is properly
   // sorted, otherwise asserts false.
 #ifndef PRODUCT
   bool verify(void);
   bool regionProperlyOrdered(HeapRegion* r) {
     int si = r->sort_index();
     return (si == -1) ||
       (si > -1 && _markedRegions.at(si) == r) ||
       (si < -1 && _cache.region_in_cache(r));
   }
 #endif
 };
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_COLLECTIONSETCHOOSER_HPP

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/collectionSetChooser.hpp@2ace1c4ee8da (annotated)

src/share/vm/gc_implementation/g1/collectionSetChooser.hpp