1 /* 2 * Copyright (c) 2014, 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_IMPLEMENTATION_G1_G1ALLOCATOR_HPP 26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCATOR_HPP 27 28 #include "gc_implementation/g1/g1AllocationContext.hpp" 29 #include "gc_implementation/g1/g1AllocRegion.hpp" 30 #include "gc_implementation/g1/g1InCSetState.hpp" 31 #include "gc_implementation/shared/parGCAllocBuffer.hpp" 32 33 // Interface to keep track of which regions G1 is currently allocating into. 34 class AllocRegionManager : public CHeapObj<mtGC> { 35 friend class VMStructs; 36 protected: 37 G1CollectedHeap* _g1h; 38 39 // Outside of GC pauses, the number of bytes used in all regions other 40 // than the current allocation region. 41 size_t _summary_bytes_used; 42 43 public: 44 AllocRegionManager(G1CollectedHeap* heap) : 45 _g1h(heap), _summary_bytes_used(0) { } 46 47 static AllocRegionManager* create_allocator(G1CollectedHeap* g1h); 48 49 virtual void init_mutator_alloc_region() = 0; 50 virtual void release_mutator_alloc_region() = 0; 51 52 virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info) = 0; 53 virtual void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) = 0; 54 virtual void abandon_gc_alloc_regions() = 0; 55 56 virtual MutatorAllocRegion* mutator_alloc_region(AllocationContext_t context) = 0; 57 virtual SurvivorGCAllocRegion* survivor_gc_alloc_region(AllocationContext_t context) = 0; 58 virtual OldGCAllocRegion* old_gc_alloc_region(AllocationContext_t context) = 0; 59 virtual size_t used() = 0; 60 virtual bool is_retained_old_region(HeapRegion* hr) = 0; 61 62 void reuse_retained_old_region(EvacuationInfo& evacuation_info, 63 OldGCAllocRegion* old, 64 HeapRegion** retained); 65 66 size_t used_unlocked() const { 67 return _summary_bytes_used; 68 } 69 70 void increase_used(size_t bytes) { 71 _summary_bytes_used += bytes; 72 } 73 74 void decrease_used(size_t bytes) { 75 assert(_summary_bytes_used >= bytes, 76 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT, 77 _summary_bytes_used, bytes)); 78 _summary_bytes_used -= bytes; 79 } 80 81 void set_used(size_t bytes) { 82 _summary_bytes_used = bytes; 83 } 84 85 virtual HeapRegion* new_heap_region(uint hrs_index, 86 G1BlockOffsetSharedArray* sharedOffsetArray, 87 MemRegion mr) { 88 return new HeapRegion(hrs_index, sharedOffsetArray, mr); 89 } 90 }; 91 92 // The default allocation region manager for G1. Provides a single mutator, survivor 93 // and old generation allocation region. 94 // Can retain the old generation allocation region across GCs. 95 class DefaultAllocRegionManager : public AllocRegionManager { 96 protected: 97 // Alloc region used to satisfy mutator allocation requests. 98 MutatorAllocRegion _mutator_alloc_region; 99 100 // Alloc region used to satisfy allocation requests by the GC for 101 // survivor objects. 102 SurvivorGCAllocRegion _survivor_gc_alloc_region; 103 104 // Alloc region used to satisfy allocation requests by the GC for 105 // old objects. 106 OldGCAllocRegion _old_gc_alloc_region; 107 108 HeapRegion* _retained_old_gc_alloc_region; 109 public: 110 DefaultAllocRegionManager(G1CollectedHeap* heap) : AllocRegionManager(heap), _retained_old_gc_alloc_region(NULL) { } 111 112 virtual void init_mutator_alloc_region(); 113 virtual void release_mutator_alloc_region(); 114 115 virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info); 116 virtual void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info); 117 virtual void abandon_gc_alloc_regions(); 118 119 virtual bool is_retained_old_region(HeapRegion* hr) { 120 return _retained_old_gc_alloc_region == hr; 121 } 122 123 virtual MutatorAllocRegion* mutator_alloc_region(AllocationContext_t context) { 124 return &_mutator_alloc_region; 125 } 126 127 virtual SurvivorGCAllocRegion* survivor_gc_alloc_region(AllocationContext_t context) { 128 return &_survivor_gc_alloc_region; 129 } 130 131 virtual OldGCAllocRegion* old_gc_alloc_region(AllocationContext_t context) { 132 return &_old_gc_alloc_region; 133 } 134 135 virtual size_t used() { 136 assert(Heap_lock->owner() != NULL, 137 "Should be owned on this thread's behalf."); 138 size_t result = _summary_bytes_used; 139 140 // Read only once in case it is set to NULL concurrently 141 HeapRegion* hr = mutator_alloc_region(AllocationContext::current())->get(); 142 if (hr != NULL) { 143 result += hr->used(); 144 } 145 return result; 146 } 147 }; 148 149 // A PLAB used during garbage collection that is specific to G1. 150 class G1PLAB: public ParGCAllocBuffer { 151 private: 152 bool _retired; 153 154 public: 155 G1PLAB(size_t gclab_word_size); 156 virtual ~G1PLAB() { 157 guarantee(_retired, "Allocation buffer has not been retired"); 158 } 159 160 virtual void set_buf(HeapWord* buf) { 161 ParGCAllocBuffer::set_buf(buf); 162 _retired = false; 163 } 164 165 virtual void retire() { 166 if (_retired) { 167 return; 168 } 169 ParGCAllocBuffer::retire(); 170 _retired = true; 171 } 172 }; 173 174 // Manages the PLABs used during garbage collection. Interface for allocation from PLABs. 175 // Needs to handle multiple contexts, extra alignment in any "survivor" area and some 176 // statistics. 177 class PLABAllocator : public CHeapObj<mtGC> { 178 friend class G1ParScanThreadState; 179 protected: 180 G1CollectedHeap* _g1h; 181 182 // The survivor alignment in effect in bytes. 183 // == 0 : don't align survivors 184 // != 0 : align survivors to that alignment 185 // These values were chosen to favor the non-alignment case since some 186 // architectures have a special compare against zero instructions. 187 const uint _survivor_alignment_bytes; 188 189 size_t _alloc_buffer_waste; 190 size_t _undo_waste; 191 192 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; } 193 void add_to_undo_waste(size_t waste) { _undo_waste += waste; } 194 195 virtual void retire_alloc_buffers() = 0; 196 virtual G1PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) = 0; 197 198 // Calculate the survivor space object alignment in bytes. Returns that or 0 if 199 // there are no restrictions on survivor alignment. 200 static uint calc_survivor_alignment_bytes() { 201 assert(SurvivorAlignmentInBytes >= ObjectAlignmentInBytes, "sanity"); 202 if (SurvivorAlignmentInBytes == ObjectAlignmentInBytes) { 203 // No need to align objects in the survivors differently, return 0 204 // which means "survivor alignment is not used". 205 return 0; 206 } else { 207 assert(SurvivorAlignmentInBytes > 0, "sanity"); 208 return SurvivorAlignmentInBytes; 209 } 210 } 211 212 public: 213 PLABAllocator(G1CollectedHeap* g1h) : 214 _g1h(g1h), _survivor_alignment_bytes(calc_survivor_alignment_bytes()), 215 _alloc_buffer_waste(0), _undo_waste(0) { 216 } 217 218 static PLABAllocator* create_allocator(G1CollectedHeap* g1h); 219 220 size_t alloc_buffer_waste() { return _alloc_buffer_waste; } 221 size_t undo_waste() {return _undo_waste; } 222 223 // Allocate word_sz words in dest, either directly into the regions or by 224 // allocating a new PLAB. Returns the address of the allocated memory, NULL if 225 // not successful. 226 HeapWord* allocate_direct_or_new_plab(InCSetState dest, 227 size_t word_sz, 228 AllocationContext_t context); 229 230 // Allocate word_sz words in the PLAB of dest. Returns the address of the 231 // allocated memory, NULL if not successful. 232 HeapWord* plab_allocate(InCSetState dest, 233 size_t word_sz, 234 AllocationContext_t context) { 235 G1PLAB* buffer = alloc_buffer(dest, context); 236 if (_survivor_alignment_bytes == 0) { 237 return buffer->allocate(word_sz); 238 } else { 239 return buffer->allocate_aligned(word_sz, _survivor_alignment_bytes); 240 } 241 } 242 243 HeapWord* allocate(InCSetState dest, size_t word_sz, 244 AllocationContext_t context) { 245 HeapWord* const obj = plab_allocate(dest, word_sz, context); 246 if (obj != NULL) { 247 return obj; 248 } 249 return allocate_direct_or_new_plab(dest, word_sz, context); 250 } 251 252 void undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context) { 253 if (alloc_buffer(dest, context)->contains(obj)) { 254 assert(alloc_buffer(dest, context)->contains(obj + word_sz - 1), 255 "should contain whole object"); 256 alloc_buffer(dest, context)->undo_allocation(obj, word_sz); 257 } else { 258 CollectedHeap::fill_with_object(obj, word_sz); 259 add_to_undo_waste(word_sz); 260 } 261 } 262 }; 263 264 // The default PLAB allocator for G1. Keeps the current (single) PLAB for survivor 265 // and old generation allocation. 266 class DefaultPLABAllocator : public PLABAllocator { 267 G1PLAB _surviving_alloc_buffer; 268 G1PLAB _tenured_alloc_buffer; 269 G1PLAB* _alloc_buffers[InCSetState::Num]; 270 271 public: 272 DefaultPLABAllocator(G1CollectedHeap* g1h); 273 274 virtual G1PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) { 275 assert(dest.is_valid(), 276 err_msg("Allocation buffer index out-of-bounds: " CSETSTATE_FORMAT, dest.value())); 277 assert(_alloc_buffers[dest.value()] != NULL, 278 err_msg("Allocation buffer is NULL: " CSETSTATE_FORMAT, dest.value())); 279 return _alloc_buffers[dest.value()]; 280 } 281 282 virtual void retire_alloc_buffers() ; 283 }; 284 285 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1ALLOCATOR_HPP