1 /* 2 * Copyright (c) 2001, 2008, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 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. 8 * 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 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 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 21 * questions. 22 * 23 */ 24 25 // TenuredGeneration models the heap containing old (promoted/tenured) objects. 26 27 class ParGCAllocBufferWithBOT; 28 29 class TenuredGeneration: public OneContigSpaceCardGeneration { 30 friend class VMStructs; 31 protected: 32 // current shrinking effect: this damps shrinking when the heap gets empty. 33 size_t _shrink_factor; 34 // Some statistics from before gc started. 35 // These are gathered in the gc_prologue (and should_collect) 36 // to control growing/shrinking policy in spite of promotions. 37 size_t _capacity_at_prologue; 38 size_t _used_at_prologue; 39 40 #ifndef SERIALGC 41 // To support parallel promotion: an array of parallel allocation 42 // buffers, one per thread, initially NULL. 43 ParGCAllocBufferWithBOT** _alloc_buffers; 44 #endif // SERIALGC 45 46 // Retire all alloc buffers before a full GC, so that they will be 47 // re-allocated at the start of the next young GC. 48 void retire_alloc_buffers_before_full_gc(); 49 50 GenerationCounters* _gen_counters; 51 CSpaceCounters* _space_counters; 52 53 public: 54 TenuredGeneration(ReservedSpace rs, size_t initial_byte_size, int level, 55 GenRemSet* remset); 56 57 Generation::Name kind() { return Generation::MarkSweepCompact; } 58 59 // Printing 60 const char* name() const; 61 const char* short_name() const { return "Tenured"; } 62 bool must_be_youngest() const { return false; } 63 bool must_be_oldest() const { return true; } 64 65 // Does a "full" (forced) collection invoked on this generation collect 66 // all younger generations as well? Note that this is a 67 // hack to allow the collection of the younger gen first if the flag is 68 // set. This is better than using th policy's should_collect_gen0_first() 69 // since that causes us to do an extra unnecessary pair of restart-&-stop-world. 70 virtual bool full_collects_younger_generations() const { 71 return !CollectGen0First; 72 } 73 74 // Mark sweep support 75 void compute_new_size(); 76 77 virtual void gc_prologue(bool full); 78 virtual void gc_epilogue(bool full); 79 bool should_collect(bool full, 80 size_t word_size, 81 bool is_tlab); 82 83 virtual void collect(bool full, 84 bool clear_all_soft_refs, 85 size_t size, 86 bool is_tlab); 87 88 #ifndef SERIALGC 89 // Overrides. 90 virtual oop par_promote(int thread_num, 91 oop obj, markOop m, size_t word_sz); 92 virtual void par_promote_alloc_undo(int thread_num, 93 HeapWord* obj, size_t word_sz); 94 virtual void par_promote_alloc_done(int thread_num); 95 #endif // SERIALGC 96 97 // Performance Counter support 98 void update_counters(); 99 100 // Statistics 101 102 virtual void update_gc_stats(int level, bool full); 103 104 virtual bool promotion_attempt_is_safe(size_t max_promoted_in_bytes, 105 bool younger_handles_promotion_failure) const; 106 107 void verify_alloc_buffers_clean(); 108 };