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 // For _special spaces we need to keep track if the memory needs to be zeroed 53 // after commit or not. 54 BitMap _needs_zeroing; 55 56 // Indicates that the entire space has been committed and pinned in memory, 57 // os::commit_memory() or os::uncommit_memory() have no function. 58 bool _special; 59 60 // Indicates whether the committed space should be executable. 61 bool _executable; 62 63 // Returns the index of the page which contains the given address. 64 uintptr_t addr_to_page_index(char* addr) const; 65 // Returns the address of the given page index. 66 char* page_start(uintptr_t index); 67 // Returns the byte size of the given number of pages. 68 size_t byte_size_for_pages(size_t num); 69 70 // Returns true if the entire area is backed by committed memory. 71 bool is_area_committed(uintptr_t start, size_t size_in_pages) const; 72 // Returns true if the entire area is not backed by committed memory. 73 bool is_area_uncommitted(uintptr_t start, size_t size_in_pages) const; 74 75 public: 76 77 // Commit the given area of pages starting at start being size_in_pages large. 78 // Returns true if the given area is zero filled upon completion. 79 bool commit(uintptr_t start, size_t size_in_pages); 80 81 // Uncommit the given area of pages starting at start being size_in_pages large. 82 void uncommit(uintptr_t start, size_t size_in_pages); 83 84 // Initialization 85 G1PageBasedVirtualSpace(); 86 bool initialize_with_granularity(ReservedSpace rs, size_t page_size); 87 88 // Destruction 89 ~G1PageBasedVirtualSpace(); 90 91 // Amount of reserved memory. 92 size_t reserved_size() const; 93 // Memory used in this virtual space. 94 size_t committed_size() const; 95 // Memory left to use/expand in this virtual space. 96 size_t uncommitted_size() const; 97 98 bool contains(const void* p) const; 99 100 MemRegion reserved() { 101 MemRegion x((HeapWord*)_low_boundary, reserved_size() / HeapWordSize); 102 return x; 103 } 104 105 void release(); 106 107 void check_for_contiguity() PRODUCT_RETURN; 108 109 // Debugging 110 void print_on(outputStream* out) PRODUCT_RETURN; 111 void print(); 112 }; 113 114 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP