1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
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   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
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  24 
  25 #ifndef SHARE_GC_G1_G1REMSET_HPP
  26 #define SHARE_GC_G1_G1REMSET_HPP
  27 
  28 #include "gc/g1/g1CardTable.hpp"
  29 #include "gc/g1/g1OopClosures.hpp"
  30 #include "gc/g1/g1GCPhaseTimes.hpp"
  31 #include "gc/g1/g1RemSetSummary.hpp"
  32 #include "gc/g1/heapRegion.hpp"
  33 #include "memory/allocation.hpp"
  34 #include "memory/iterator.hpp"
  35 #include "utilities/ticks.hpp"
  36 
  37 // A G1RemSet provides ways of iterating over pointers into a selected
  38 // collection set.
  39 
  40 class BitMap;
  41 class CardTableBarrierSet;
  42 class G1BlockOffsetTable;
  43 class CodeBlobClosure;
  44 class G1CollectedHeap;
  45 class G1CMBitMap;
  46 class G1HotCardCache;
  47 class G1RemSetScanState;
  48 class G1ParScanThreadState;
  49 class G1Policy;
  50 class G1ScanObjsDuringScanRSClosure;
  51 class G1ScanObjsDuringUpdateRSClosure;
  52 class HeapRegionClaimer;
  53 
  54 // A G1RemSet in which each heap region has a rem set that records the
  55 // external heap references into it.  Uses a mod ref bs to track updates,
  56 // so that they can be used to update the individual region remsets.
  57 class G1RemSet: public CHeapObj<mtGC> {
  58 private:
  59   G1RemSetScanState* _scan_state;
  60 
  61   G1RemSetSummary _prev_period_summary;
  62 
  63   // Scan all remembered sets of the collection set for references into the collection
  64   // set.
  65   void scan_rem_set(G1ParScanThreadState* pss, uint worker_i);
  66 
  67   // Flush remaining refinement buffers for cross-region references to either evacuate references
  68   // into the collection set or update the remembered set.
  69   void update_rem_set(G1ParScanThreadState* pss, uint worker_i);
  70 
  71   G1CollectedHeap* _g1h;
  72   size_t _num_conc_refined_cards; // Number of cards refined concurrently to the mutator.
  73 
  74   G1CardTable*           _ct;
  75   G1Policy*              _g1p;
  76   G1HotCardCache*        _hot_card_cache;
  77 
  78 public:
  79   // Gives an approximation on how many threads can be expected to add records to
  80   // a remembered set in parallel. This can be used for sizing data structures to
  81   // decrease performance losses due to data structure sharing.
  82   // Examples for quantities that influence this value are the maximum number of
  83   // mutator threads, maximum number of concurrent refinement or GC threads.
  84   static uint num_par_rem_sets();
  85 
  86   // Initialize data that depends on the heap size being known.
  87   void initialize(size_t capacity, uint max_regions);
  88 
  89   G1RemSet(G1CollectedHeap* g1h,
  90            G1CardTable* ct,
  91            G1HotCardCache* hot_card_cache);
  92   ~G1RemSet();
  93 
  94   // Process all oops in the collection set from the cards in the refinement buffers and
  95   // remembered sets using pss.
  96   //
  97   // Further applies heap_region_codeblobs on the oops of the unmarked nmethods on the strong code
  98   // roots list for each region in the collection set.
  99   void oops_into_collection_set_do(G1ParScanThreadState* pss, uint worker_i);
 100 
 101   // Prepare for and cleanup after an oops_into_collection_set_do
 102   // call.  Must call each of these once before and after (in sequential
 103   // code) any thread calls oops_into_collection_set_do.
 104   void prepare_for_oops_into_collection_set_do();
 105   void cleanup_after_oops_into_collection_set_do();
 106 
 107   G1RemSetScanState* scan_state() const { return _scan_state; }
 108 
 109   // Refine the card corresponding to "card_ptr". Safe to be called concurrently
 110   // to the mutator.
 111   void refine_card_concurrently(jbyte* card_ptr,
 112                                 uint worker_i);
 113 
 114   // Refine the card corresponding to "card_ptr", applying the given closure to
 115   // all references found. Must only be called during gc.
 116   // Returns whether the card has been scanned.
 117   bool refine_card_during_gc(jbyte* card_ptr, G1ScanObjsDuringUpdateRSClosure* update_rs_cl);
 118 
 119   // Print accumulated summary info from the start of the VM.
 120   void print_summary_info();
 121 
 122   // Print accumulated summary info from the last time called.
 123   void print_periodic_summary_info(const char* header, uint period_count);
 124 
 125   size_t num_conc_refined_cards() const { return _num_conc_refined_cards; }
 126 
 127   // Rebuilds the remembered set by scanning from bottom to TARS for all regions
 128   // using the given work gang.
 129   void rebuild_rem_set(G1ConcurrentMark* cm, WorkGang* workers, uint worker_id_offset);
 130 };
 131 
 132 class G1ScanRSForRegionClosure : public HeapRegionClosure {
 133   G1CollectedHeap* _g1h;
 134   G1CardTable *_ct;
 135 
 136   G1ParScanThreadState* _pss;
 137   G1ScanObjsDuringScanRSClosure* _scan_objs_on_card_cl;
 138 
 139   G1RemSetScanState* _scan_state;
 140 
 141   G1GCPhaseTimes::GCParPhases _phase;
 142 
 143   uint   _worker_i;
 144 
 145   size_t _cards_scanned;
 146   size_t _cards_claimed;
 147   size_t _cards_skipped;
 148 
 149   Tickspan _rem_set_root_scan_time;
 150   Tickspan _rem_set_trim_partially_time;
 151 
 152   Tickspan _strong_code_root_scan_time;
 153   Tickspan _strong_code_trim_partially_time;
 154 
 155   void claim_card(size_t card_index, const uint region_idx_for_card);
 156   void scan_card(MemRegion mr, uint region_idx_for_card);
 157 
 158   void scan_rem_set_roots(HeapRegion* r);
 159   void scan_strong_code_roots(HeapRegion* r);
 160 public:
 161   G1ScanRSForRegionClosure(G1RemSetScanState* scan_state,
 162                            G1ScanObjsDuringScanRSClosure* scan_obj_on_card,
 163                            G1ParScanThreadState* pss,
 164                            G1GCPhaseTimes::GCParPhases phase,
 165                            uint worker_i);
 166 
 167   bool do_heap_region(HeapRegion* r);
 168 
 169   Tickspan rem_set_root_scan_time() const { return _rem_set_root_scan_time; }
 170   Tickspan rem_set_trim_partially_time() const { return _rem_set_trim_partially_time; }
 171 
 172   Tickspan strong_code_root_scan_time() const { return _strong_code_root_scan_time;  }
 173   Tickspan strong_code_root_trim_partially_time() const { return _strong_code_trim_partially_time; }
 174 
 175   size_t cards_scanned() const { return _cards_scanned; }
 176   size_t cards_claimed() const { return _cards_claimed; }
 177   size_t cards_skipped() const { return _cards_skipped; }
 178 };
 179 
 180 #endif // SHARE_GC_G1_G1REMSET_HPP