1 /*
2 * Copyright (c) 2014, 2019, 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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 */
24
25 #ifndef SHARE_GC_G1_G1PAGEBASEDVIRTUALSPACE_HPP
26 #define SHARE_GC_G1_G1PAGEBASEDVIRTUALSPACE_HPP
27
28 #include "memory/memRegion.hpp"
29 #include "memory/virtualspace.hpp"
30 #include "utilities/align.hpp"
31 #include "utilities/bitMap.hpp"
32
33 class WorkGang;
34
35 // Virtual space management helper for a virtual space with an OS page allocation
36 // granularity.
37 // (De-)Allocation requests are always OS page aligned by passing a page index
38 // and multiples of pages.
39 // For systems that only commits of memory in a given size (always greater than
40 // page size) the base address is required to be aligned to that page size.
41 // The actual size requested need not be aligned to that page size, but the size
42 // of the reservation passed may be rounded up to this page size. Any fragment
43 // (less than the page size) of the actual size at the tail of the request will
44 // be committed using OS small pages.
45 // The implementation gives an error when trying to commit or uncommit pages that
46 // have already been committed or uncommitted.
47 class G1PageBasedVirtualSpace {
48 friend class VMStructs;
49 private:
50 // Reserved area addresses.
51 char* _low_boundary;
52 char* _high_boundary;
53
54 // The size of the tail in bytes of the handled space that needs to be committed
55 // using small pages.
56 size_t _tail_size;
57
58 // The preferred page size used for commit/uncommit in bytes.
59 size_t _page_size;
60
61 // Bitmap used for verification of commit/uncommit operations.
62 CHeapBitMap _committed;
63
64 // Bitmap used to keep track of which pages are dirty or not for _special
65 // spaces. This is needed because for those spaces the underlying memory
66 // will only be zero filled the first time it is committed. Calls to commit
67 // will use this bitmap and return whether or not the memory is zero filled.
68 CHeapBitMap _dirty;
69
70 // Indicates that the entire space has been committed and pinned in memory,
71 // os::commit_memory() or os::uncommit_memory() have no function.
72 bool _special;
73
74 // Indicates whether the committed space should be executable.
75 bool _executable;
76
77 MemoryType _memory_type;
78
79 // Helper function for committing memory. Commit the given memory range by using
80 // _page_size pages as much as possible and the remainder with small sized pages.
81 void commit_internal(size_t start_page, size_t end_page);
82 // Commit num_pages pages of _page_size size starting from start. All argument
83 // checking has been performed.
84 void commit_preferred_pages(size_t start_page, size_t end_page);
85 // Commit space at the high end of the space that needs to be committed with small
86 // sized pages.
87 void commit_tail();
88
89 // Uncommit the given memory range.
90 void uncommit_internal(size_t start_page, size_t end_page);
91
92 // Pretouch the given memory range.
93 void pretouch_internal(size_t start_page, size_t end_page);
94
95 // Returns the index of the page which contains the given address.
96 size_t addr_to_page_index(char* addr) const;
97 // Returns the address of the given page index.
98 char* page_start(size_t index) const;
99
100 // Is the given page index the last page?
101 bool is_last_page(size_t index) const { return index == (_committed.size() - 1); }
102 // Is the given page index the first after last page?
103 bool is_after_last_page(size_t index) const;
104 // Is the last page only partially covered by this space?
105 bool is_last_page_partial() const { return !is_aligned(_high_boundary, _page_size); }
106 // Returns the end address of the given page bounded by the reserved space.
107 char* bounded_end_addr(size_t end_page) const;
108
109 // Returns true if the entire area is backed by committed memory.
110 bool is_area_committed(size_t start_page, size_t size_in_pages) const;
111 // Returns true if the entire area is not backed by committed memory.
112 bool is_area_uncommitted(size_t start_page, size_t size_in_pages) const;
113
114 void initialize_with_page_size(ReservedSpace rs, size_t used_size, size_t page_size, MemoryType type);
115 public:
116
117 // Request the given memory to be located at the given node index.
118 void request_memory_on_node(size_t start_page, size_t size_in_pages, uint node_index);
119
120 // Commit the given area of pages starting at start being size_in_pages large.
121 // Returns true if the given area is zero filled upon completion.
122 bool commit(size_t start_page, size_t size_in_pages);
123
124 // Uncommit the given area of pages starting at start being size_in_pages large.
125 void uncommit(size_t start_page, size_t size_in_pages);
126
127 void pretouch(size_t start_page, size_t size_in_pages, WorkGang* pretouch_gang = NULL);
128
129 // Initialize the given reserved space with the given base address and the size
130 // actually used.
131 // Prefer to commit in page_size chunks.
132 G1PageBasedVirtualSpace(ReservedSpace rs, size_t used_size, size_t page_size, MemoryType type);
133
134 // Destruction
135 ~G1PageBasedVirtualSpace();
136
137 // Amount of reserved memory.
138 size_t reserved_size() const;
139 // Memory used in this virtual space.
140 size_t committed_size() const;
141 // Memory left to use/expand in this virtual space.
142 size_t uncommitted_size() const;
143
144 void commit_and_set_special();
145
146 bool contains(const void* p) const;
147
148 MemRegion reserved() {
149 MemRegion x((HeapWord*)_low_boundary, reserved_size() / HeapWordSize);
150 return x;
151 }
152
153 void check_for_contiguity() PRODUCT_RETURN;
154
155 // Debugging
156 void print_on(outputStream* out) PRODUCT_RETURN;
157 void print();
158 };
159
160 #endif // SHARE_GC_G1_G1PAGEBASEDVIRTUALSPACE_HPP