1 /*
2 * Copyright (c) 2001, 2020, 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.
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23 */
24
25 #ifndef SHARE_GC_PARALLEL_PSYOUNGGEN_HPP
26 #define SHARE_GC_PARALLEL_PSYOUNGGEN_HPP
27
28 #include "gc/parallel/mutableSpace.hpp"
29 #include "gc/parallel/objectStartArray.hpp"
30 #include "gc/parallel/psGenerationCounters.hpp"
31 #include "gc/parallel/psVirtualspace.hpp"
32 #include "gc/parallel/spaceCounters.hpp"
33
34 class PSYoungGen : public CHeapObj<mtGC> {
35 friend class VMStructs;
36 friend class ParallelScavengeHeap;
37 friend class AdjoiningGenerations;
38
39 private:
40 MemRegion _reserved;
41 PSVirtualSpace* _virtual_space;
42
43 // Spaces
44 MutableSpace* _eden_space;
45 MutableSpace* _from_space;
46 MutableSpace* _to_space;
47
48 // Sizing information, in bytes, set in constructor
49 const size_t _min_gen_size;
50 const size_t _max_gen_size;
51
52 // Performance counters
53 PSGenerationCounters* _gen_counters;
54 SpaceCounters* _eden_counters;
55 SpaceCounters* _from_counters;
56 SpaceCounters* _to_counters;
57
58 // Initialize the space boundaries
59 void compute_initial_space_boundaries();
60
61 // Space boundary helper
62 void set_space_boundaries(size_t eden_size, size_t survivor_size);
63
64 bool resize_generation(size_t eden_size, size_t survivor_size);
65 void resize_spaces(size_t eden_size, size_t survivor_size);
66
67 // Adjust the spaces to be consistent with the virtual space.
68 void post_resize();
69
70 // Given a desired shrinkage in the size of the young generation,
71 // return the actual size available for shrinkage.
72 size_t limit_gen_shrink(size_t desired_change);
73 // returns the number of bytes available from the current size
74 // down to the minimum generation size.
75 size_t available_to_min_gen();
76 // Return the number of bytes available for shrinkage considering
77 // the location the live data in the generation.
78 size_t available_to_live();
79
80 void initialize(ReservedSpace rs, size_t inital_size, size_t alignment);
81 void initialize_work();
82 void initialize_virtual_space(ReservedSpace rs, size_t initial_size, size_t alignment);
83
84 public:
85 // Initialize the generation.
86 PSYoungGen(ReservedSpace rs,
87 size_t initial_byte_size,
88 size_t minimum_byte_size,
89 size_t maximum_byte_size);
90
91 MemRegion reserved() const { return _reserved; }
92
93 bool is_in(const void* p) const {
94 return _virtual_space->contains((void *)p);
95 }
96
97 bool is_in_reserved(const void* p) const {
98 return reserved().contains((void *)p);
99 }
100
101 MutableSpace* eden_space() const { return _eden_space; }
102 MutableSpace* from_space() const { return _from_space; }
103 MutableSpace* to_space() const { return _to_space; }
104 PSVirtualSpace* virtual_space() const { return _virtual_space; }
105
106 // Called during/after GC
107 void swap_spaces();
108
109 // Resize generation using suggested free space size and survivor size
110 // NOTE: "eden_size" and "survivor_size" are suggestions only. Current
111 // heap layout (particularly, live objects in from space) might
112 // not allow us to use these values.
113 void resize(size_t eden_size, size_t survivor_size);
114
115 // Size info
116 size_t capacity_in_bytes() const;
117 size_t used_in_bytes() const;
118 size_t free_in_bytes() const;
119
120 size_t capacity_in_words() const;
121 size_t used_in_words() const;
122 size_t free_in_words() const;
123
124 size_t min_gen_size() const { return _min_gen_size; }
125 size_t max_gen_size() const { return _max_gen_size; }
126
127 bool is_maximal_no_gc() const {
128 return true; // Never expands except at a GC
129 }
130
131 // Allocation
132 HeapWord* allocate(size_t word_size) {
133 HeapWord* result = eden_space()->cas_allocate(word_size);
134 return result;
135 }
136
137 HeapWord* volatile* top_addr() const { return eden_space()->top_addr(); }
138 HeapWord** end_addr() const { return eden_space()->end_addr(); }
139
140 // Iteration.
141 void oop_iterate(OopIterateClosure* cl);
142 void object_iterate(ObjectClosure* cl);
143
144 void reset_survivors_after_shrink();
145
146 // Performance Counter support
147 void update_counters();
148
149 // Debugging - do not use for time critical operations
150 void print() const;
151 virtual void print_on(outputStream* st) const;
152 const char* name() const { return "PSYoungGen"; }
153
154 void verify();
155
156 // Space boundary invariant checker
157 void space_invariants() PRODUCT_RETURN;
158
159 // Helper for mangling survivor spaces.
160 void mangle_survivors(MutableSpace* s1,
161 MemRegion s1MR,
162 MutableSpace* s2,
163 MemRegion s2MR) PRODUCT_RETURN;
164
165 void record_spaces_top() PRODUCT_RETURN;
166 };
167
168 #endif // SHARE_GC_PARALLEL_PSYOUNGGEN_HPP