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 // 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 commit size. 39 // The actual size requested need not be aligned to the commit size, but the size 40 // of the reservation passed may be rounded up to the commit size. Any fragment 41 // (less than the commit 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 preferred commit/uncommit granularity in bytes. 53 size_t _commit_size; 54 55 // Bitmap used for verification of commit/uncommit operations. 56 BitMap _committed; 57 58 // Bitmap used to keep track of which pages are dirty or not for _special 59 // spaces. This is needed because for those spaces the underlying memory 60 // will only be zero filled the first time it is committed. Calls to commit 61 // will use this bitmap and return whether or not the memory is zero filled. 62 BitMap _dirty; 63 64 // Indicates that the entire space has been committed and pinned in memory, 65 // os::commit_memory() or os::uncommit_memory() have no function. 66 bool _special; 67 68 // Indicates whether the committed space should be executable. 69 bool _executable; 70 71 // Commit the given memory range by using _commit_size pages as much as possible 72 // and the remainder with small sized pages. The start address must be _commit_size 73 // aligned. 74 void commit_internal(char* start, char* end); 75 // Uncommit the given memory range. 76 void uncommit_internal(char* start, char* end); 77 78 // Returns the index of the page which contains the given address. 79 uintptr_t addr_to_page_index(char* addr) const; 80 // Returns the address of the given page index. 81 char* page_start(uintptr_t index); 82 // Returns the address of the end of the page given the page index ranging 83 // from 0..size_in_pages-2. For the last page, return _high_boundary. 84 char* page_end(uintptr_t index); 85 86 // Returns true if the entire area is backed by committed memory. 87 bool is_area_committed(uintptr_t start, size_t size_in_pages) const; 88 // Returns true if the entire area is not backed by committed memory. 89 bool is_area_uncommitted(uintptr_t start, size_t size_in_pages) const; 90 91 public: 92 93 // Commit the given area of pages starting at start being size_in_pages large. 94 // Returns true if the given area is zero filled upon completion. 95 bool commit(uintptr_t start, size_t size_in_pages); 96 97 // Uncommit the given area of pages starting at start being size_in_pages large. 98 void uncommit(uintptr_t start, size_t size_in_pages); 99 100 // Initialization 101 G1PageBasedVirtualSpace(); 102 // Initialize the given reserved space with the given base address and actual size. 103 // Prefer to commit in commit_size chunks. 104 bool initialize_with_granularity(ReservedSpace rs, size_t actual_size, size_t commit_size); 105 106 // Destruction 107 ~G1PageBasedVirtualSpace(); 108 109 // Amount of reserved memory. 110 size_t reserved_size() const; 111 // Memory used in this virtual space. 112 size_t committed_size() const; 113 // Memory left to use/expand in this virtual space. 114 size_t uncommitted_size() const; 115 116 bool contains(const void* p) const; 117 118 MemRegion reserved() { 119 MemRegion x((HeapWord*)_low_boundary, reserved_size() / HeapWordSize); 120 return x; 121 } 122 123 void release(); 124 125 void check_for_contiguity() PRODUCT_RETURN; 126 127 // Debugging 128 void print_on(outputStream* out) PRODUCT_RETURN; 129 void print(); 130 }; 131 132 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP