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comparison src/share/vm/gc_implementation/g1/g1PageBasedVirtualSpace.hpp @ 20337:1f1d373cd044

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8038423: G1: Decommit memory within heap Summary: Allow G1 to decommit memory of arbitrary regions within the heap and their associated auxiliary data structures card table, BOT, hot card cache, and mark bitmaps. Reviewed-by: mgerdin, brutisso, jwilhelm
author tschatzl
date Thu, 21 Aug 2014 11:47:10 +0200
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20336:6701abbc4441 20337:1f1d373cd044
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
21 * questions.
22 *
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 "runtime/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 // The implementation gives an error when trying to commit or uncommit pages that
38 // have already been committed or uncommitted.
39 class G1PageBasedVirtualSpace VALUE_OBJ_CLASS_SPEC {
40 friend class VMStructs;
41 private:
42 // Reserved area addresses.
43 char* _low_boundary;
44 char* _high_boundary;
45
46 // The commit/uncommit granularity in bytes.
47 size_t _page_size;
48
49 // Bitmap used for verification of commit/uncommit operations.
50 BitMap _committed;
51
52 // Indicates that the entire space has been committed and pinned in memory,
53 // os::commit_memory() or os::uncommit_memory() have no function.
54 bool _special;
55
56 // Indicates whether the committed space should be executable.
57 bool _executable;
58
59 // Returns the index of the page which contains the given address.
60 uintptr_t addr_to_page_index(char* addr) const;
61 // Returns the address of the given page index.
62 char* page_start(uintptr_t index);
63 // Returns the byte size of the given number of pages.
64 size_t byte_size_for_pages(size_t num);
65
66 // Returns true if the entire area is backed by committed memory.
67 bool is_area_committed(uintptr_t start, size_t size_in_pages) const;
68 // Returns true if the entire area is not backed by committed memory.
69 bool is_area_uncommitted(uintptr_t start, size_t size_in_pages) const;
70
71 public:
72
73 // Commit the given area of pages starting at start being size_in_pages large.
74 MemRegion commit(uintptr_t start, size_t size_in_pages);
75
76 // Uncommit the given area of pages starting at start being size_in_pages large.
77 MemRegion uncommit(uintptr_t start, size_t size_in_pages);
78
79 bool special() const { return _special; }
80
81 // Initialization
82 G1PageBasedVirtualSpace();
83 bool initialize_with_granularity(ReservedSpace rs, size_t page_size);
84
85 // Destruction
86 ~G1PageBasedVirtualSpace();
87
88 // Amount of reserved memory.
89 size_t reserved_size() const;
90 // Memory used in this virtual space.
91 size_t committed_size() const;
92 // Memory left to use/expand in this virtual space.
93 size_t uncommitted_size() const;
94
95 bool contains(const void* p) const;
96
97 MemRegion reserved() {
98 MemRegion x((HeapWord*)_low_boundary, reserved_size() / HeapWordSize);
99 return x;
100 }
101
102 void release();
103
104 void check_for_contiguity() PRODUCT_RETURN;
105
106 // Debugging
107 void print_on(outputStream* out) PRODUCT_RETURN;
108 void print();
109 };
110
111 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP