1 /*
2 * Copyright (c) 2014, 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
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23 */
24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP
27
28 #include "memory/allocation.hpp"
29 #include "memory/memRegion.hpp"
30 #include "memory/virtualspace.hpp"
31 #include "utilities/bitMap.hpp"
32
33 // Virtual space management helper for a virtual space with an OS page allocation
34 // granularity.
35 // (De-)Allocation requests are always OS page aligned by passing a page index
36 // and multiples of pages.
37 // For systems that only commits of memory in a given size (always greater than
38 // page size) the base address is required to be aligned to that page size.
39 // The actual size requested need not be aligned to that page size, but the size
40 // of the reservation passed may be rounded up to this page size. Any fragment
41 // (less than the page size) of the actual size at the tail of the request will
42 // be committed using OS small pages.
43 // The implementation gives an error when trying to commit or uncommit pages that
44 // have already been committed or uncommitted.
45 class G1PageBasedVirtualSpace VALUE_OBJ_CLASS_SPEC {
46 friend class VMStructs;
47 private:
48 // Reserved area addresses.
49 char* _low_boundary;
50 char* _high_boundary;
51
52 // The size of the tail in bytes of the handled space that needs to be committed
53 // using small pages.
54 size_t _tail_size;
55
56 // The preferred page size used for commit/uncommit in bytes.
57 size_t _page_size;
58
59 // Bitmap used for verification of commit/uncommit operations.
60 BitMap _committed;
61
62 // Bitmap used to keep track of which pages are dirty or not for _special
63 // spaces. This is needed because for those spaces the underlying memory
64 // will only be zero filled the first time it is committed. Calls to commit
65 // will use this bitmap and return whether or not the memory is zero filled.
66 BitMap _dirty;
67
68 // Indicates that the entire space has been committed and pinned in memory,
69 // os::commit_memory() or os::uncommit_memory() have no function.
70 bool _special;
71
72 // Indicates whether the committed space should be executable.
73 bool _executable;
74
75 // Helper function for committing memory. Commit the given memory range by using
76 // _page_size pages as much as possible and the remainder with small sized pages.
77 void commit_internal(size_t start_page, size_t end_page);
78 // Commit num_pages pages of _page_size size starting from start. All argument
79 // checking has been performed.
80 void commit_preferred_pages(size_t start_page, size_t end_page);
81 // Commit space at the high end of the space that needs to be committed with small
82 // sized pages.
83 void commit_tail();
84
85 // Uncommit the given memory range.
86 void uncommit_internal(size_t start_page, size_t end_page);
87
88 // Pretouch the given memory range.
89 void pretouch_internal(size_t start_page, size_t end_page);
90
91 // Returns the index of the page which contains the given address.
92 uintptr_t addr_to_page_index(char* addr) const;
93 // Returns the address of the given page index.
94 char* page_start(size_t index) const;
95
96 // Is the given page index the last page?
97 bool is_last_page(size_t index) const { return index == (_committed.size() - 1); }
98 // Is the given page index the first after last page?
99 bool is_after_last_page(size_t index) const;
100 // Is the last page only partially covered by this space?
101 bool is_last_page_partial() const { return !is_ptr_aligned(_high_boundary, _page_size); }
102 // Returns the end address of the given page bounded by the reserved space.
103 char* bounded_end_addr(size_t end_page) const;
104
105 // Returns true if the entire area is backed by committed memory.
106 bool is_area_committed(size_t start_page, size_t size_in_pages) const;
107 // Returns true if the entire area is not backed by committed memory.
108 bool is_area_uncommitted(size_t start_page, size_t size_in_pages) const;
109
110 void initialize_with_page_size(ReservedSpace rs, size_t used_size, size_t page_size);
111 public:
112
113 // Commit the given area of pages starting at start being size_in_pages large.
114 // Returns true if the given area is zero filled upon completion.
115 bool commit(size_t start_page, size_t size_in_pages);
116
117 // Uncommit the given area of pages starting at start being size_in_pages large.
118 void uncommit(size_t start_page, size_t size_in_pages);
119
120 // Initialize the given reserved space with the given base address and the size
121 // actually used.
122 // Prefer to commit in page_size chunks.
123 G1PageBasedVirtualSpace(ReservedSpace rs, size_t used_size, size_t page_size);
124
125 // Destruction
126 ~G1PageBasedVirtualSpace();
127
128 // Amount of reserved memory.
129 size_t reserved_size() const;
130 // Memory used in this virtual space.
131 size_t committed_size() const;
132 // Memory left to use/expand in this virtual space.
133 size_t uncommitted_size() const;
134
135 bool contains(const void* p) const;
136
137 MemRegion reserved() {
138 MemRegion x((HeapWord*)_low_boundary, reserved_size() / HeapWordSize);
139 return x;
140 }
141
142 void release();
143
144 void check_for_contiguity() PRODUCT_RETURN;
145
146 // Debugging
147 void print_on(outputStream* out) PRODUCT_RETURN;
148 void print();
149 };
150
151 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP