1 /* 2 * Copyright (c) 2001, 2015, 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_G1_HEAPREGIONMANAGER_HPP 26 #define SHARE_VM_GC_G1_HEAPREGIONMANAGER_HPP 27 28 #include "gc/g1/g1BiasedArray.hpp" 29 #include "gc/g1/g1RegionToSpaceMapper.hpp" 30 #include "gc/g1/heapRegionSet.hpp" 31 #include "services/memoryUsage.hpp" 32 33 class HeapRegion; 34 class HeapRegionClosure; 35 class HeapRegionClaimer; 36 class FreeRegionList; 37 38 class G1HeapRegionTable : public G1BiasedMappedArray<HeapRegion*> { 39 protected: 40 virtual HeapRegion* default_value() const { return NULL; } 41 }; 42 43 // This class keeps track of the actual heap memory, auxiliary data 44 // and its metadata (i.e., HeapRegion instances) and the list of free regions. 45 // 46 // This allows maximum flexibility for deciding what to commit or uncommit given 47 // a request from outside. 48 // 49 // HeapRegions are kept in the _regions array in address order. A region's 50 // index in the array corresponds to its index in the heap (i.e., 0 is the 51 // region at the bottom of the heap, 1 is the one after it, etc.). Two 52 // regions that are consecutive in the array should also be adjacent in the 53 // address space (i.e., region(i).end() == region(i+1).bottom(). 54 // 55 // We create a HeapRegion when we commit the region's address space 56 // for the first time. When we uncommit the address space of a 57 // region we retain the HeapRegion to be able to re-use it in the 58 // future (in case we recommit it). 59 // 60 // We keep track of three lengths: 61 // 62 // * _num_committed (returned by length()) is the number of currently 63 // committed regions. These may not be contiguous. 64 // * _allocated_heapregions_length (not exposed outside this class) is the 65 // number of regions+1 for which we have HeapRegions. 66 // * max_length() returns the maximum number of regions the heap can have. 67 // 68 69 class HeapRegionManager: public CHeapObj<mtGC> { 70 friend class VMStructs; 71 friend class HeapRegionClaimer; 72 73 G1HeapRegionTable _regions; 74 75 G1RegionToSpaceMapper* _heap_mapper; 76 G1RegionToSpaceMapper* _prev_bitmap_mapper; 77 G1RegionToSpaceMapper* _next_bitmap_mapper; 78 G1RegionToSpaceMapper* _bot_mapper; 79 G1RegionToSpaceMapper* _cardtable_mapper; 80 G1RegionToSpaceMapper* _card_counts_mapper; 81 82 FreeRegionList _free_list; 83 84 // Each bit in this bitmap indicates that the corresponding region is available 85 // for allocation. 86 BitMap _available_map; 87 88 // The number of regions committed in the heap. 89 uint _num_committed; 90 91 // Internal only. The highest heap region +1 we allocated a HeapRegion instance for. 92 uint _allocated_heapregions_length; 93 94 HeapWord* heap_bottom() const { return _regions.bottom_address_mapped(); } 95 HeapWord* heap_end() const {return _regions.end_address_mapped(); } 96 97 void make_regions_available(uint index, uint num_regions = 1); 98 99 // Pass down commit calls to the VirtualSpace. 100 void commit_regions(uint index, size_t num_regions = 1); 101 void uncommit_regions(uint index, size_t num_regions = 1); 102 103 // Notify other data structures about change in the heap layout. 104 void update_committed_space(HeapWord* old_end, HeapWord* new_end); 105 106 // Find a contiguous set of empty or uncommitted regions of length num and return 107 // the index of the first region or G1_NO_HRM_INDEX if the search was unsuccessful. 108 // If only_empty is true, only empty regions are considered. 109 // Searches from bottom to top of the heap, doing a first-fit. 110 uint find_contiguous(size_t num, bool only_empty); 111 // Finds the next sequence of unavailable regions starting from start_idx. Returns the 112 // length of the sequence found. If this result is zero, no such sequence could be found, 113 // otherwise res_idx indicates the start index of these regions. 114 uint find_unavailable_from_idx(uint start_idx, uint* res_idx) const; 115 // Finds the next sequence of empty regions starting from start_idx, going backwards in 116 // the heap. Returns the length of the sequence found. If this value is zero, no 117 // sequence could be found, otherwise res_idx contains the start index of this range. 118 uint find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const; 119 // Allocate a new HeapRegion for the given index. 120 HeapRegion* new_heap_region(uint hrm_index); 121 #ifdef ASSERT 122 public: 123 bool is_free(HeapRegion* hr) const; 124 #endif 125 // Returns whether the given region is available for allocation. 126 bool is_available(uint region) const; 127 128 public: 129 // Empty constructor, we'll initialize it with the initialize() method. 130 HeapRegionManager() : _regions(), _heap_mapper(NULL), _num_committed(0), 131 _next_bitmap_mapper(NULL), _prev_bitmap_mapper(NULL), _bot_mapper(NULL), 132 _allocated_heapregions_length(0), _available_map(), 133 _free_list("Free list", new MasterFreeRegionListMtSafeChecker()) 134 { } 135 136 void initialize(G1RegionToSpaceMapper* heap_storage, 137 G1RegionToSpaceMapper* prev_bitmap, 138 G1RegionToSpaceMapper* next_bitmap, 139 G1RegionToSpaceMapper* bot, 140 G1RegionToSpaceMapper* cardtable, 141 G1RegionToSpaceMapper* card_counts); 142 143 // Return the "dummy" region used for G1AllocRegion. This is currently a hardwired 144 // new HeapRegion that owns HeapRegion at index 0. Since at the moment we commit 145 // the heap from the lowest address, this region (and its associated data 146 // structures) are available and we do not need to check further. 147 HeapRegion* get_dummy_region() { return new_heap_region(0); } 148 149 // Return the HeapRegion at the given index. Assume that the index 150 // is valid. 151 inline HeapRegion* at(uint index) const; 152 153 // Return the next region (by index) that is part of the same 154 // humongous object that hr is part of. 155 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 156 157 // If addr is within the committed space return its corresponding 158 // HeapRegion, otherwise return NULL. 159 inline HeapRegion* addr_to_region(HeapWord* addr) const; 160 161 // Insert the given region into the free region list. 162 inline void insert_into_free_list(HeapRegion* hr); 163 164 // Insert the given region list into the global free region list. 165 void insert_list_into_free_list(FreeRegionList* list) { 166 _free_list.add_ordered(list); 167 } 168 169 HeapRegion* allocate_free_region(bool is_old) { 170 HeapRegion* hr = _free_list.remove_region(is_old); 171 172 if (hr != NULL) { 173 assert(hr->next() == NULL, "Single region should not have next"); 174 assert(is_available(hr->hrm_index()), "Must be committed"); 175 } 176 return hr; 177 } 178 179 inline void allocate_free_regions_starting_at(uint first, uint num_regions); 180 181 // Remove all regions from the free list. 182 void remove_all_free_regions() { 183 _free_list.remove_all(); 184 } 185 186 // Return the number of committed free regions in the heap. 187 uint num_free_regions() const { 188 return _free_list.length(); 189 } 190 191 size_t total_capacity_bytes() const { 192 return num_free_regions() * HeapRegion::GrainBytes; 193 } 194 195 // Return the number of available (uncommitted) regions. 196 uint available() const { return max_length() - length(); } 197 198 // Return the number of regions that have been committed in the heap. 199 uint length() const { return _num_committed; } 200 201 // Return the maximum number of regions in the heap. 202 uint max_length() const { return (uint)_regions.length(); } 203 204 MemoryUsage get_auxiliary_data_memory_usage() const; 205 206 MemRegion reserved() const { return MemRegion(heap_bottom(), heap_end()); } 207 208 // Expand the sequence to reflect that the heap has grown. Either create new 209 // HeapRegions, or re-use existing ones. Returns the number of regions the 210 // sequence was expanded by. If a HeapRegion allocation fails, the resulting 211 // number of regions might be smaller than what's desired. 212 uint expand_by(uint num_regions); 213 214 // Makes sure that the regions from start to start+num_regions-1 are available 215 // for allocation. Returns the number of regions that were committed to achieve 216 // this. 217 uint expand_at(uint start, uint num_regions); 218 219 // Find a contiguous set of empty regions of length num. Returns the start index of 220 // that set, or G1_NO_HRM_INDEX. 221 uint find_contiguous_only_empty(size_t num) { return find_contiguous(num, true); } 222 // Find a contiguous set of empty or unavailable regions of length num. Returns the 223 // start index of that set, or G1_NO_HRM_INDEX. 224 uint find_contiguous_empty_or_unavailable(size_t num) { return find_contiguous(num, false); } 225 226 HeapRegion* next_region_in_heap(const HeapRegion* r) const; 227 228 // Find the highest free or uncommitted region in the reserved heap, 229 // and if uncommitted, commit it. If none are available, return G1_NO_HRM_INDEX. 230 // Set the 'expanded' boolean true if a new region was committed. 231 uint find_highest_free(bool* expanded); 232 233 // Allocate the regions that contain the address range specified, committing the 234 // regions if necessary. Return false if any of the regions is already committed 235 // and not free, and return the number of regions newly committed in commit_count. 236 bool allocate_containing_regions(MemRegion range, size_t* commit_count); 237 238 // Apply blk->doHeapRegion() on all committed regions in address order, 239 // terminating the iteration early if doHeapRegion() returns true. 240 void iterate(HeapRegionClosure* blk) const; 241 242 void par_iterate(HeapRegionClosure* blk, uint worker_id, HeapRegionClaimer* hrclaimer, bool concurrent) const; 243 244 // Uncommit up to num_regions_to_remove regions that are completely free. 245 // Return the actual number of uncommitted regions. 246 uint shrink_by(uint num_regions_to_remove); 247 248 // Uncommit a number of regions starting at the specified index, which must be available, 249 // empty, and free. 250 void shrink_at(uint index, size_t num_regions); 251 252 void verify(); 253 254 // Do some sanity checking. 255 void verify_optional() PRODUCT_RETURN; 256 }; 257 258 // The HeapRegionClaimer is used during parallel iteration over heap regions, 259 // allowing workers to claim heap regions, gaining exclusive rights to these regions. 260 class HeapRegionClaimer : public StackObj { 261 uint _n_workers; 262 uint _n_regions; 263 uint* _claims; 264 265 static const uint Unclaimed = 0; 266 static const uint Claimed = 1; 267 268 public: 269 HeapRegionClaimer(uint n_workers); 270 ~HeapRegionClaimer(); 271 272 inline uint n_regions() const { 273 return _n_regions; 274 } 275 276 // Calculate the starting region for given worker so 277 // that they do not all start from the same region. 278 uint start_region_for_worker(uint worker_id) const; 279 280 // Check if region has been claimed with this HRClaimer. 281 bool is_region_claimed(uint region_index) const; 282 283 // Claim the given region, returns true if successfully claimed. 284 bool claim_region(uint region_index); 285 }; 286 #endif // SHARE_VM_GC_G1_HEAPREGIONMANAGER_HPP 287