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. 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_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 // Helper function for committing memory. Commit the given memory range by using 78 // _page_size pages as much as possible and the remainder with small sized pages. 79 void commit_internal(size_t start_page, size_t end_page); 80 // Commit num_pages pages of _page_size size starting from start. All argument 81 // checking has been performed. 82 void commit_preferred_pages(size_t start_page, size_t end_page); 83 // Commit space at the high end of the space that needs to be committed with small 84 // sized pages. 85 void commit_tail(); 86 87 // Uncommit the given memory range. 88 void uncommit_internal(size_t start_page, size_t end_page); 89 90 // Pretouch the given memory range. 91 void pretouch_internal(size_t start_page, size_t end_page); 92 93 // Returns the index of the page which contains the given address. 94 size_t addr_to_page_index(char* addr) const; 95 96 // Is the given page index the last page? is_last_page(size_t index) const97 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? is_last_page_partial() const101 bool is_last_page_partial() const { return !is_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 void pretouch(size_t start_page, size_t size_in_pages, WorkGang* pretouch_gang = NULL); 121 122 // Initialize the given reserved space with the given base address and the size 123 // actually used. 124 // Prefer to commit in page_size chunks. 125 G1PageBasedVirtualSpace(ReservedSpace rs, size_t used_size, size_t page_size); 126 127 // Destruction 128 ~G1PageBasedVirtualSpace(); 129 130 // Amount of reserved memory. 131 size_t reserved_size() const; 132 // Memory used in this virtual space. 133 size_t committed_size() const; 134 // Memory left to use/expand in this virtual space. 135 size_t uncommitted_size() const; 136 137 void commit_and_set_special(); 138 139 bool contains(const void* p) const; 140 reserved()141 MemRegion reserved() { 142 MemRegion x((HeapWord*)_low_boundary, reserved_size() / HeapWordSize); 143 return x; 144 } 145 146 void check_for_contiguity() PRODUCT_RETURN; 147 148 // Returns the address of the given page index. 149 char* page_start(size_t index) const; 150 size_t page_size() const; 151 152 // Debugging 153 void print_on(outputStream* out) PRODUCT_RETURN; 154 void print(); 155 }; 156 157 #endif // SHARE_GC_G1_G1PAGEBASEDVIRTUALSPACE_HPP 158