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_G1_G1ALLOCATOR_HPP 26 #define SHARE_VM_GC_G1_G1ALLOCATOR_HPP 27 28 #include "gc/g1/g1AllocRegion.hpp" 29 #include "gc/g1/g1AllocationContext.hpp" 30 #include "gc/g1/g1InCSetState.hpp" 31 #include "gc/shared/collectedHeap.hpp" 32 #include "gc/shared/plab.hpp" 33 34 class EvacuationInfo; 35 36 // Interface to keep track of which regions G1 is currently allocating into. Provides 37 // some accessors (e.g. allocating into them, or getting their occupancy). 38 // Also keeps track of retained regions across GCs. 39 class G1Allocator : public CHeapObj<mtGC> { 40 friend class VMStructs; 41 protected: 42 G1CollectedHeap* _g1h; 43 44 static inline bool is_humongous(size_t word_size); 45 46 virtual MutatorAllocRegion* mutator_alloc_region(AllocationContext_t context) = 0; 47 48 virtual bool survivor_is_full(AllocationContext_t context) const = 0; 49 virtual bool old_is_full(AllocationContext_t context) const = 0; 50 51 virtual void set_survivor_full(AllocationContext_t context) = 0; 52 virtual void set_old_full(AllocationContext_t context) = 0; 53 54 // Accessors to the allocation regions. 55 virtual SurvivorGCAllocRegion* survivor_gc_alloc_region(AllocationContext_t context) = 0; 56 virtual OldGCAllocRegion* old_gc_alloc_region(AllocationContext_t context) = 0; 57 58 // Allocation attempt during GC for a survivor object / PLAB. 59 inline HeapWord* survivor_attempt_allocation(size_t min_word_size, 60 size_t desired_word_size, 61 size_t* actual_word_size, 62 AllocationContext_t context); 63 // Allocation attempt during GC for an old object / PLAB. 64 inline HeapWord* old_attempt_allocation(size_t min_word_size, 65 size_t desired_word_size, 66 size_t* actual_word_size, 67 AllocationContext_t context); 68 69 // Second-level mutator allocation attempt: take the Heap_lock and 70 // retry the allocation attempt, potentially scheduling a GC 71 // pause. This should only be used for non-humongous allocations. 72 HeapWord* attempt_allocation_slow(size_t word_size, 73 AllocationContext_t context, 74 uint* gc_count_before_ret, 75 uint* gclocker_retry_count_ret); 76 77 // Takes the Heap_lock and attempts a humongous allocation. It can 78 // potentially schedule a GC pause. 79 HeapWord* attempt_allocation_humongous(size_t word_size, 80 uint* gc_count_before_ret, 81 uint* gclocker_retry_count_ret); 82 83 // Initialize a contiguous set of free regions of length num_regions 84 // and starting at index first so that they appear as a single 85 // humongous region. 86 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 87 uint num_regions, 88 size_t word_size, 89 AllocationContext_t context); 90 91 // Attempt to allocate a humongous object of the given size. Return 92 // NULL if unsuccessful. 93 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 94 95 // Returns the number of regions the humongous object of the given word size 96 // requires. 97 static size_t humongous_obj_size_in_regions(size_t word_size); 98 99 // The following three methods take a gc_count_before_ret 100 // parameter which is used to return the GC count if the method 101 // returns NULL. Given that we are required to read the GC count 102 // while holding the Heap_lock, and these paths will take the 103 // Heap_lock at some point, it's easier to get them to read the GC 104 // count while holding the Heap_lock before they return NULL instead 105 // of the caller (namely: mem_allocate()) having to also take the 106 // Heap_lock just to read the GC count. 107 108 // First-level mutator allocation attempt: try to allocate out of 109 // the mutator alloc region without taking the Heap_lock. This 110 // should only be used for non-humongous allocations. 111 inline HeapWord* attempt_allocation(size_t word_size, 112 uint* gc_count_before_ret, 113 uint* gclocker_retry_count_ret); 114 115 public: 116 G1Allocator(G1CollectedHeap* heap) : _g1h(heap) { } 117 virtual ~G1Allocator() { } 118 119 static G1Allocator* create_allocator(G1CollectedHeap* g1h); 120 121 #ifdef ASSERT 122 // Do we currently have an active mutator region to allocate into? 123 bool has_mutator_alloc_region(AllocationContext_t context) { return mutator_alloc_region(context)->get() != NULL; } 124 #endif 125 126 // Allocation attempt that should be called during safepoints (e.g., 127 // at the end of a successful GC). expect_null_mutator_alloc_region 128 // specifies whether the mutator alloc region is expected to be NULL 129 // or not. 130 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 131 AllocationContext_t context, 132 bool expect_null_mutator_alloc_region); 133 134 // This is a non-product method that is helpful for testing. It is 135 // called at the end of a GC and artificially expands the heap by 136 // allocating a number of dead regions. This way we can induce very 137 // frequent marking cycles and stress the cleanup / concurrent 138 // cleanup code more (as all the regions that will be allocated by 139 // this method will be found dead by the marking cycle). 140 void allocate_dummy_regions(size_t word_size) PRODUCT_RETURN; 141 142 // The following two methods, allocate_new_tlab() and 143 // mem_allocate(), are the two main entry points from the runtime 144 // into the G1's allocation routines. They have the following 145 // assumptions: 146 // 147 // * They should both be called outside safepoints. 148 // 149 // * They should both be called without holding the Heap_lock. 150 // 151 // * All allocation requests for new TLABs should go to 152 // allocate_new_tlab(). 153 // 154 // * All non-TLAB allocation requests should go to mem_allocate(). 155 // 156 // * If either call cannot satisfy the allocation request using the 157 // current allocating region, they will try to get a new one. If 158 // this fails, they will attempt to do an evacuation pause and 159 // retry the allocation. 160 // 161 // * If all allocation attempts fail, even after trying to schedule 162 // an evacuation pause, allocate_new_tlab() will return NULL, 163 // whereas mem_allocate() will attempt a heap expansion and/or 164 // schedule a Full GC. 165 // 166 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 167 // should never be called with word_size being humongous. All 168 // humongous allocation requests should go to mem_allocate() which 169 // will satisfy them with a special path. 170 171 HeapWord* allocate_new_tlab(size_t word_size); 172 173 virtual HeapWord* mem_allocate(size_t word_size, 174 bool* gc_overhead_limit_was_exceeded); 175 176 virtual void init_mutator_alloc_region() = 0; 177 virtual void release_mutator_alloc_region() = 0; 178 179 virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info) = 0; 180 virtual void release_gc_alloc_regions(EvacuationInfo& evacuation_info) = 0; 181 virtual void abandon_gc_alloc_regions() = 0; 182 183 // Management of retained regions. 184 185 virtual bool is_retained_old_region(HeapRegion* hr) = 0; 186 void reuse_retained_old_region(EvacuationInfo& evacuation_info, 187 OldGCAllocRegion* old, 188 HeapRegion** retained); 189 190 // Allocate blocks of memory during mutator time. 191 192 inline HeapWord* attempt_allocation(size_t word_size, AllocationContext_t context); 193 inline HeapWord* attempt_allocation_locked(size_t word_size, AllocationContext_t context); 194 inline HeapWord* attempt_allocation_force(size_t word_size, AllocationContext_t context); 195 196 size_t unsafe_max_tlab_alloc(AllocationContext_t context); 197 198 // Allocate blocks of memory during garbage collection. Will ensure an 199 // allocation region, either by picking one or expanding the 200 // heap, and then allocate a block of the given size. The block 201 // may not be a humongous - it must fit into a single heap region. 202 HeapWord* par_allocate_during_gc(InCSetState dest, 203 size_t word_size, 204 AllocationContext_t context); 205 206 HeapWord* par_allocate_during_gc(InCSetState dest, 207 size_t min_word_size, 208 size_t desired_word_size, 209 size_t* actual_word_size, 210 AllocationContext_t context); 211 212 virtual size_t used_in_alloc_regions() = 0; 213 }; 214 215 // The default allocation region manager for G1. Provides a single mutator, survivor 216 // and old generation allocation region. 217 // Can retain the (single) old generation allocation region across GCs. 218 class G1DefaultAllocator : public G1Allocator { 219 private: 220 bool _survivor_is_full; 221 bool _old_is_full; 222 protected: 223 // Alloc region used to satisfy mutator allocation requests. 224 MutatorAllocRegion _mutator_alloc_region; 225 226 // Alloc region used to satisfy allocation requests by the GC for 227 // survivor objects. 228 SurvivorGCAllocRegion _survivor_gc_alloc_region; 229 230 // Alloc region used to satisfy allocation requests by the GC for 231 // old objects. 232 OldGCAllocRegion _old_gc_alloc_region; 233 234 HeapRegion* _retained_old_gc_alloc_region; 235 public: 236 G1DefaultAllocator(G1CollectedHeap* heap); 237 238 virtual bool survivor_is_full(AllocationContext_t context) const; 239 virtual bool old_is_full(AllocationContext_t context) const ; 240 241 virtual void set_survivor_full(AllocationContext_t context); 242 virtual void set_old_full(AllocationContext_t context); 243 244 virtual void init_mutator_alloc_region(); 245 virtual void release_mutator_alloc_region(); 246 247 virtual void init_gc_alloc_regions(EvacuationInfo& evacuation_info); 248 virtual void release_gc_alloc_regions(EvacuationInfo& evacuation_info); 249 virtual void abandon_gc_alloc_regions(); 250 251 virtual bool is_retained_old_region(HeapRegion* hr) { 252 return _retained_old_gc_alloc_region == hr; 253 } 254 255 virtual MutatorAllocRegion* mutator_alloc_region(AllocationContext_t context) { 256 return &_mutator_alloc_region; 257 } 258 259 virtual SurvivorGCAllocRegion* survivor_gc_alloc_region(AllocationContext_t context) { 260 return &_survivor_gc_alloc_region; 261 } 262 263 virtual OldGCAllocRegion* old_gc_alloc_region(AllocationContext_t context) { 264 return &_old_gc_alloc_region; 265 } 266 267 virtual size_t used_in_alloc_regions() { 268 assert(Heap_lock->owner() != NULL, 269 "Should be owned on this thread's behalf."); 270 size_t result = 0; 271 272 // Read only once in case it is set to NULL concurrently 273 HeapRegion* hr = mutator_alloc_region(AllocationContext::current())->get(); 274 if (hr != NULL) { 275 result += hr->used(); 276 } 277 return result; 278 } 279 }; 280 281 class G1PLAB: public PLAB { 282 private: 283 bool _retired; 284 285 public: 286 G1PLAB(size_t gclab_word_size); 287 virtual ~G1PLAB() { 288 guarantee(_retired, "Allocation buffer has not been retired"); 289 } 290 291 // The amount of space in words wasted within the PLAB including 292 // waste due to refills and alignment. 293 size_t wasted() const { return _wasted; } 294 295 virtual void set_buf(HeapWord* buf, size_t word_size) { 296 PLAB::set_buf(buf, word_size); 297 _retired = false; 298 } 299 300 virtual void retire() { 301 if (_retired) { 302 return; 303 } 304 PLAB::retire(); 305 _retired = true; 306 } 307 308 virtual void flush_and_retire_stats(PLABStats* stats) { 309 PLAB::flush_and_retire_stats(stats); 310 _retired = true; 311 } 312 }; 313 314 // Manages the PLABs used during garbage collection. Interface for allocation from PLABs. 315 // Needs to handle multiple contexts, extra alignment in any "survivor" area and some 316 // statistics. 317 class G1PLABAllocator : public CHeapObj<mtGC> { 318 friend class G1ParScanThreadState; 319 protected: 320 G1CollectedHeap* _g1h; 321 G1Allocator* _allocator; 322 323 // The survivor alignment in effect in bytes. 324 // == 0 : don't align survivors 325 // != 0 : align survivors to that alignment 326 // These values were chosen to favor the non-alignment case since some 327 // architectures have a special compare against zero instructions. 328 const uint _survivor_alignment_bytes; 329 330 // Number of words allocated directly (not counting PLAB allocation). 331 size_t _direct_allocated[InCSetState::Num]; 332 333 virtual void flush_and_retire_stats() = 0; 334 virtual G1PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) = 0; 335 336 // Calculate the survivor space object alignment in bytes. Returns that or 0 if 337 // there are no restrictions on survivor alignment. 338 static uint calc_survivor_alignment_bytes() { 339 assert(SurvivorAlignmentInBytes >= ObjectAlignmentInBytes, "sanity"); 340 if (SurvivorAlignmentInBytes == ObjectAlignmentInBytes) { 341 // No need to align objects in the survivors differently, return 0 342 // which means "survivor alignment is not used". 343 return 0; 344 } else { 345 assert(SurvivorAlignmentInBytes > 0, "sanity"); 346 return SurvivorAlignmentInBytes; 347 } 348 } 349 350 HeapWord* allocate_new_plab(InCSetState dest, 351 size_t word_sz, 352 AllocationContext_t context); 353 354 bool may_throw_away_buffer(size_t const allocation_word_sz, size_t const buffer_size) const; 355 public: 356 G1PLABAllocator(G1Allocator* allocator); 357 virtual ~G1PLABAllocator() { } 358 359 static G1PLABAllocator* create_allocator(G1Allocator* allocator); 360 361 virtual void waste(size_t& wasted, size_t& undo_wasted) = 0; 362 363 // Allocate word_sz words in dest, either directly into the regions or by 364 // allocating a new PLAB. Returns the address of the allocated memory, NULL if 365 // not successful. Plab_refill_failed indicates whether an attempt to refill the 366 // PLAB failed or not. 367 HeapWord* allocate_direct_or_new_plab(InCSetState dest, 368 size_t word_sz, 369 AllocationContext_t context, 370 bool* plab_refill_failed); 371 372 // Allocate word_sz words in the PLAB of dest. Returns the address of the 373 // allocated memory, NULL if not successful. 374 inline HeapWord* plab_allocate(InCSetState dest, 375 size_t word_sz, 376 AllocationContext_t context); 377 378 HeapWord* allocate(InCSetState dest, 379 size_t word_sz, 380 AllocationContext_t context, 381 bool* refill_failed) { 382 HeapWord* const obj = plab_allocate(dest, word_sz, context); 383 if (obj != NULL) { 384 return obj; 385 } 386 return allocate_direct_or_new_plab(dest, word_sz, context, refill_failed); 387 } 388 389 void undo_allocation(InCSetState dest, HeapWord* obj, size_t word_sz, AllocationContext_t context); 390 }; 391 392 // The default PLAB allocator for G1. Keeps the current (single) PLAB for survivor 393 // and old generation allocation. 394 class G1DefaultPLABAllocator : public G1PLABAllocator { 395 G1PLAB _surviving_alloc_buffer; 396 G1PLAB _tenured_alloc_buffer; 397 G1PLAB* _alloc_buffers[InCSetState::Num]; 398 399 public: 400 G1DefaultPLABAllocator(G1Allocator* _allocator); 401 402 virtual G1PLAB* alloc_buffer(InCSetState dest, AllocationContext_t context) { 403 assert(dest.is_valid(), 404 "Allocation buffer index out-of-bounds: " CSETSTATE_FORMAT, dest.value()); 405 assert(_alloc_buffers[dest.value()] != NULL, 406 "Allocation buffer is NULL: " CSETSTATE_FORMAT, dest.value()); 407 return _alloc_buffers[dest.value()]; 408 } 409 410 virtual void flush_and_retire_stats(); 411 412 virtual void waste(size_t& wasted, size_t& undo_wasted); 413 }; 414 415 // G1ArchiveAllocator is used to allocate memory in archive 416 // regions. Such regions are not modifiable by GC, being neither 417 // scavenged nor compacted, or even marked in the object header. 418 // They can contain no pointers to non-archive heap regions, 419 class G1ArchiveAllocator : public CHeapObj<mtGC> { 420 421 protected: 422 G1CollectedHeap* _g1h; 423 424 // The current allocation region 425 HeapRegion* _allocation_region; 426 427 // Regions allocated for the current archive range. 428 GrowableArray<HeapRegion*> _allocated_regions; 429 430 // The number of bytes used in the current range. 431 size_t _summary_bytes_used; 432 433 // Current allocation window within the current region. 434 HeapWord* _bottom; 435 HeapWord* _top; 436 HeapWord* _max; 437 438 // Allocate a new region for this archive allocator. 439 // Allocation is from the top of the reserved heap downward. 440 bool alloc_new_region(); 441 442 public: 443 G1ArchiveAllocator(G1CollectedHeap* g1h) : 444 _g1h(g1h), 445 _allocation_region(NULL), 446 _allocated_regions((ResourceObj::set_allocation_type((address) &_allocated_regions, 447 ResourceObj::C_HEAP), 448 2), true /* C_Heap */), 449 _summary_bytes_used(0), 450 _bottom(NULL), 451 _top(NULL), 452 _max(NULL) { } 453 454 virtual ~G1ArchiveAllocator() { 455 assert(_allocation_region == NULL, "_allocation_region not NULL"); 456 } 457 458 static G1ArchiveAllocator* create_allocator(G1CollectedHeap* g1h); 459 460 // Allocate memory for an individual object. 461 HeapWord* archive_mem_allocate(size_t word_size); 462 463 // Return the memory ranges used in the current archive, after 464 // aligning to the requested alignment. 465 void complete_archive(GrowableArray<MemRegion>* ranges, 466 size_t end_alignment_in_bytes); 467 468 // The number of bytes allocated by this allocator. 469 size_t used() { 470 return _summary_bytes_used; 471 } 472 473 // Clear the count of bytes allocated in prior G1 regions. This 474 // must be done when recalculate_use is used to reset the counter 475 // for the generic allocator, since it counts bytes in all G1 476 // regions, including those still associated with this allocator. 477 void clear_used() { 478 _summary_bytes_used = 0; 479 } 480 481 }; 482 483 #endif // SHARE_VM_GC_G1_G1ALLOCATOR_HPP