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 page size used for commit/uncommit in bytes. 53 size_t _page_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 _page_size pages as much as possible 72 // and the remainder with small sized pages. The start address must be _page_size 73 // aligned. 74 void commit_internal(size_t start_page, size_t end_page); 75 // Commit num_pages full pages of _page_size size starting from start. All argument 76 // checking has been performed. 77 void commit_full_pages(size_t start_page, size_t end_page); 78 // Commit the tail area. 79 void commit_tail(); 80 81 // Uncommit the given memory range. 82 void uncommit_internal(size_t start_page, size_t end_page); 83 84 // Pretouch the given memory range. 85 void pretouch_internal(size_t start_page, size_t end_page); 86 87 // Returns the index of the page which contains the given address. 88 uintptr_t addr_to_page_index(char* addr) const; 89 // Returns the address of the given page index. 90 char* page_start(size_t index); 91 92 // Is the given page index the last page? 93 bool is_last_page(size_t index) { return index == (_committed.size() - 1); } 94 // Is the given page index the first after last page? 95 bool is_after_last_page(size_t index); 96 // Is the last page only partially covered by this space? 97 bool is_last_page_partial() { return !is_ptr_aligned(_high_boundary, _page_size); } 98 // Returns the end address of the given page bounded by the reserved space. 99 char* bounded_end_addr(size_t end_page); 100 101 // Returns true if the entire area is backed by committed memory. 102 bool is_area_committed(size_t start, size_t size_in_pages) const; 103 // Returns true if the entire area is not backed by committed memory. 104 bool is_area_uncommitted(size_t start, size_t size_in_pages) const; 105 106 void initialize_with_page_size(ReservedSpace rs, size_t used_size, size_t page_size); 107 public: 108 109 // Commit the given area of pages starting at start being size_in_pages large. 110 // Returns true if the given area is zero filled upon completion. 111 bool commit(size_t start, size_t size_in_pages); 112 113 // Uncommit the given area of pages starting at start being size_in_pages large. 114 void uncommit(size_t start, size_t size_in_pages); 115 116 // Initialize the given reserved space with the given base address and the size 117 // actually used. 118 // Prefer to commit in page_size chunks. 119 G1PageBasedVirtualSpace(ReservedSpace rs, size_t used_size, size_t page_size); 120 121 // Destruction 122 ~G1PageBasedVirtualSpace(); 123 124 // Amount of reserved memory. 125 size_t reserved_size() const; 126 // Memory used in this virtual space. 127 size_t committed_size() const; 128 // Memory left to use/expand in this virtual space. 129 size_t uncommitted_size() const; 130 131 bool contains(const void* p) const; 132 133 MemRegion reserved() { 134 MemRegion x((HeapWord*)_low_boundary, reserved_size() / HeapWordSize); 135 return x; 136 } 137 138 void release(); 139 140 void check_for_contiguity() PRODUCT_RETURN; 141 142 // Debugging 143 void print_on(outputStream* out) PRODUCT_RETURN; 144 void print(); 145 }; 146 147 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP