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1 /*
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2 * Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 // TenuredGeneration models the heap containing old (promoted/tenured) objects.
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26
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27 class ParGCAllocBufferWithBOT;
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28
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29 class TenuredGeneration: public OneContigSpaceCardGeneration {
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30 friend class VMStructs;
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31 protected:
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32 // current shrinking effect: this damps shrinking when the heap gets empty.
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33 size_t _shrink_factor;
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34 // Some statistics from before gc started.
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35 // These are gathered in the gc_prologue (and should_collect)
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36 // to control growing/shrinking policy in spite of promotions.
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37 size_t _capacity_at_prologue;
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38 size_t _used_at_prologue;
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39
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40 #ifndef SERIALGC
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41 // To support parallel promotion: an array of parallel allocation
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42 // buffers, one per thread, initially NULL.
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43 ParGCAllocBufferWithBOT** _alloc_buffers;
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44 #endif // SERIALGC
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45
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46 // Retire all alloc buffers before a full GC, so that they will be
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47 // re-allocated at the start of the next young GC.
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48 void retire_alloc_buffers_before_full_gc();
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49
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50 GenerationCounters* _gen_counters;
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51 CSpaceCounters* _space_counters;
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52
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53 public:
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54 TenuredGeneration(ReservedSpace rs, size_t initial_byte_size, int level,
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55 GenRemSet* remset);
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56
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57 Generation::Name kind() { return Generation::MarkSweepCompact; }
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58
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59 // Printing
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60 const char* name() const;
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61 const char* short_name() const { return "Tenured"; }
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62 bool must_be_youngest() const { return false; }
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63 bool must_be_oldest() const { return true; }
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64
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65 // Does a "full" (forced) collection invoked on this generation collect
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66 // all younger generations as well? Note that this is a
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67 // hack to allow the collection of the younger gen first if the flag is
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68 // set. This is better than using th policy's should_collect_gen0_first()
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69 // since that causes us to do an extra unnecessary pair of restart-&-stop-world.
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70 virtual bool full_collects_younger_generations() const {
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71 return !CollectGen0First;
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72 }
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73
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74 // Mark sweep support
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75 void compute_new_size();
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76 int allowed_dead_ratio() const;
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77
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78 virtual void gc_prologue(bool full);
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79 virtual void gc_epilogue(bool full);
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80 bool should_collect(bool full,
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81 size_t word_size,
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82 bool is_tlab);
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83
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84 virtual void collect(bool full,
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85 bool clear_all_soft_refs,
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86 size_t size,
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87 bool is_tlab);
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88
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89 #ifndef SERIALGC
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90 // Overrides.
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91 virtual oop par_promote(int thread_num,
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92 oop obj, markOop m, size_t word_sz);
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93 virtual void par_promote_alloc_undo(int thread_num,
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94 HeapWord* obj, size_t word_sz);
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95 virtual void par_promote_alloc_done(int thread_num);
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96 #endif // SERIALGC
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97
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98 // Performance Counter support
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99 void update_counters();
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100
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101 // Statistics
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102
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103 virtual void update_gc_stats(int level, bool full);
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104
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105 virtual bool promotion_attempt_is_safe(size_t max_promoted_in_bytes,
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106 bool younger_handles_promotion_failure) const;
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107
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108 void verify_alloc_buffers_clean();
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109 };
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