1 /* 2 * Copyright (c) 2014, 2020, 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 #include "precompiled.hpp" 26 #include "gc/g1/g1Allocator.inline.hpp" 27 #include "gc/g1/g1CollectedHeap.inline.hpp" 28 #include "gc/g1/g1CollectionSet.hpp" 29 #include "gc/g1/g1OopClosures.inline.hpp" 30 #include "gc/g1/g1ParScanThreadState.inline.hpp" 31 #include "gc/g1/g1RootClosures.hpp" 32 #include "gc/g1/g1StringDedup.hpp" 33 #include "gc/g1/g1Trace.hpp" 34 #include "gc/shared/taskqueue.inline.hpp" 35 #include "memory/allocation.inline.hpp" 36 #include "oops/access.inline.hpp" 37 #include "oops/oop.inline.hpp" 38 #include "runtime/prefetch.inline.hpp" 39 40 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, 41 G1RedirtyCardsQueueSet* rdcqs, 42 uint worker_id, 43 size_t young_cset_length, 44 size_t optional_cset_length) 45 : _g1h(g1h), 46 _task_queue(g1h->task_queue(worker_id)), 47 _rdcq(rdcqs), 48 _ct(g1h->card_table()), 49 _closures(NULL), 50 _plab_allocator(NULL), 51 _age_table(false), 52 _tenuring_threshold(g1h->policy()->tenuring_threshold()), 53 _scanner(g1h, this), 54 _worker_id(worker_id), 55 _last_enqueued_card(SIZE_MAX), 56 _stack_trim_upper_threshold(GCDrainStackTargetSize * 2 + 1), 57 _stack_trim_lower_threshold(GCDrainStackTargetSize), 58 _trim_ticks(), 59 _surviving_young_words_base(NULL), 60 _surviving_young_words(NULL), 61 _surviving_words_length(young_cset_length + 1), 62 _old_gen_is_full(false), 63 _num_optional_regions(optional_cset_length), 64 _numa(g1h->numa()), 65 _obj_alloc_stat(NULL) 66 { 67 // We allocate number of young gen regions in the collection set plus one 68 // entries, since entry 0 keeps track of surviving bytes for non-young regions. 69 // We also add a few elements at the beginning and at the end in 70 // an attempt to eliminate cache contention 71 size_t array_length = PADDING_ELEM_NUM + _surviving_words_length + PADDING_ELEM_NUM; 72 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); 73 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 74 memset(_surviving_young_words, 0, _surviving_words_length * sizeof(size_t)); 75 76 _plab_allocator = new G1PLABAllocator(_g1h->allocator()); 77 78 // The dest for Young is used when the objects are aged enough to 79 // need to be moved to the next space. 80 _dest[G1HeapRegionAttr::Young] = G1HeapRegionAttr::Old; 81 _dest[G1HeapRegionAttr::Old] = G1HeapRegionAttr::Old; 82 83 _closures = G1EvacuationRootClosures::create_root_closures(this, _g1h); 84 85 _oops_into_optional_regions = new G1OopStarChunkedList[_num_optional_regions]; 86 87 initialize_numa_stats(); 88 } 89 90 size_t G1ParScanThreadState::flush(size_t* surviving_young_words) { 91 _rdcq.flush(); 92 flush_numa_stats(); 93 // Update allocation statistics. 94 _plab_allocator->flush_and_retire_stats(); 95 _g1h->policy()->record_age_table(&_age_table); 96 97 size_t sum = 0; 98 for (uint i = 0; i < _surviving_words_length; i++) { 99 surviving_young_words[i] += _surviving_young_words[i]; 100 sum += _surviving_young_words[i]; 101 } 102 return sum; 103 } 104 105 G1ParScanThreadState::~G1ParScanThreadState() { 106 delete _plab_allocator; 107 delete _closures; 108 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base); 109 delete[] _oops_into_optional_regions; 110 FREE_C_HEAP_ARRAY(size_t, _obj_alloc_stat); 111 } 112 113 size_t G1ParScanThreadState::lab_waste_words() const { 114 return _plab_allocator->waste(); 115 } 116 117 size_t G1ParScanThreadState::lab_undo_waste_words() const { 118 return _plab_allocator->undo_waste(); 119 } 120 121 #ifdef ASSERT 122 void G1ParScanThreadState::verify_task(narrowOop* task) const { 123 assert(task != NULL, "invariant"); 124 assert(UseCompressedOops, "sanity"); 125 oop p = RawAccess<>::oop_load(task); 126 assert(_g1h->is_in_g1_reserved(p), 127 "task=" PTR_FORMAT " p=" PTR_FORMAT, p2i(task), p2i(p)); 128 } 129 130 void G1ParScanThreadState::verify_task(oop* task) const { 131 assert(task != NULL, "invariant"); 132 oop p = RawAccess<>::oop_load(task); 133 assert(_g1h->is_in_g1_reserved(p), 134 "task=" PTR_FORMAT " p=" PTR_FORMAT, p2i(task), p2i(p)); 135 } 136 137 void G1ParScanThreadState::verify_task(PartialArrayScanTask task) const { 138 // Must be in the collection set--it's already been copied. 139 oop p = task.to_source_array(); 140 assert(_g1h->is_in_cset(p), "p=" PTR_FORMAT, p2i(p)); 141 } 142 143 void G1ParScanThreadState::verify_task(ScannerTask task) const { 144 if (task.is_narrow_oop_ptr()) { 145 verify_task(task.to_narrow_oop_ptr()); 146 } else if (task.is_oop_ptr()) { 147 verify_task(task.to_oop_ptr()); 148 } else if (task.is_partial_array_task()) { 149 verify_task(task.to_partial_array_task()); 150 } else { 151 ShouldNotReachHere(); 152 } 153 } 154 #endif // ASSERT 155 156 void G1ParScanThreadState::trim_queue() { 157 do { 158 // Fully drain the queue. 159 trim_queue_to_threshold(0); 160 } while (!_task_queue->is_empty()); 161 } 162 163 HeapWord* G1ParScanThreadState::allocate_in_next_plab(G1HeapRegionAttr* dest, 164 size_t word_sz, 165 bool previous_plab_refill_failed, 166 uint node_index) { 167 168 assert(dest->is_in_cset_or_humongous(), "Unexpected dest: %s region attr", dest->get_type_str()); 169 170 // Right now we only have two types of regions (young / old) so 171 // let's keep the logic here simple. We can generalize it when necessary. 172 if (dest->is_young()) { 173 bool plab_refill_in_old_failed = false; 174 HeapWord* const obj_ptr = _plab_allocator->allocate(G1HeapRegionAttr::Old, 175 word_sz, 176 &plab_refill_in_old_failed, 177 node_index); 178 // Make sure that we won't attempt to copy any other objects out 179 // of a survivor region (given that apparently we cannot allocate 180 // any new ones) to avoid coming into this slow path again and again. 181 // Only consider failed PLAB refill here: failed inline allocations are 182 // typically large, so not indicative of remaining space. 183 if (previous_plab_refill_failed) { 184 _tenuring_threshold = 0; 185 } 186 187 if (obj_ptr != NULL) { 188 dest->set_old(); 189 } else { 190 // We just failed to allocate in old gen. The same idea as explained above 191 // for making survivor gen unavailable for allocation applies for old gen. 192 _old_gen_is_full = plab_refill_in_old_failed; 193 } 194 return obj_ptr; 195 } else { 196 _old_gen_is_full = previous_plab_refill_failed; 197 assert(dest->is_old(), "Unexpected dest region attr: %s", dest->get_type_str()); 198 // no other space to try. 199 return NULL; 200 } 201 } 202 203 G1HeapRegionAttr G1ParScanThreadState::next_region_attr(G1HeapRegionAttr const region_attr, markWord const m, uint& age) { 204 if (region_attr.is_young()) { 205 age = !m.has_displaced_mark_helper() ? m.age() 206 : m.displaced_mark_helper().age(); 207 if (age < _tenuring_threshold) { 208 return region_attr; 209 } 210 } 211 return dest(region_attr); 212 } 213 214 void G1ParScanThreadState::report_promotion_event(G1HeapRegionAttr const dest_attr, 215 oop const old, size_t word_sz, uint age, 216 HeapWord * const obj_ptr, uint node_index) const { 217 PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_attr, node_index); 218 if (alloc_buf->contains(obj_ptr)) { 219 _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz * HeapWordSize, age, 220 dest_attr.type() == G1HeapRegionAttr::Old, 221 alloc_buf->word_sz() * HeapWordSize); 222 } else { 223 _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz * HeapWordSize, age, 224 dest_attr.type() == G1HeapRegionAttr::Old); 225 } 226 } 227 228 oop G1ParScanThreadState::copy_to_survivor_space(G1HeapRegionAttr const region_attr, 229 oop const old, 230 markWord const old_mark) { 231 const size_t word_sz = old->size(); 232 233 uint age = 0; 234 G1HeapRegionAttr dest_attr = next_region_attr(region_attr, old_mark, age); 235 // The second clause is to prevent premature evacuation failure in case there 236 // is still space in survivor, but old gen is full. 237 if (_old_gen_is_full && dest_attr.is_old()) { 238 return handle_evacuation_failure_par(old, old_mark); 239 } 240 HeapRegion* const from_region = _g1h->heap_region_containing(old); 241 uint node_index = from_region->node_index(); 242 243 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_attr, word_sz, node_index); 244 245 // PLAB allocations should succeed most of the time, so we'll 246 // normally check against NULL once and that's it. 247 if (obj_ptr == NULL) { 248 bool plab_refill_failed = false; 249 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(dest_attr, word_sz, &plab_refill_failed, node_index); 250 if (obj_ptr == NULL) { 251 assert(region_attr.is_in_cset(), "Unexpected region attr type: %s", region_attr.get_type_str()); 252 obj_ptr = allocate_in_next_plab(&dest_attr, word_sz, plab_refill_failed, node_index); 253 if (obj_ptr == NULL) { 254 // This will either forward-to-self, or detect that someone else has 255 // installed a forwarding pointer. 256 return handle_evacuation_failure_par(old, old_mark); 257 } 258 } 259 update_numa_stats(node_index); 260 261 if (_g1h->_gc_tracer_stw->should_report_promotion_events()) { 262 // The events are checked individually as part of the actual commit 263 report_promotion_event(dest_attr, old, word_sz, age, obj_ptr, node_index); 264 } 265 } 266 267 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded"); 268 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap"); 269 270 #ifndef PRODUCT 271 // Should this evacuation fail? 272 if (_g1h->evacuation_should_fail()) { 273 // Doing this after all the allocation attempts also tests the 274 // undo_allocation() method too. 275 _plab_allocator->undo_allocation(dest_attr, obj_ptr, word_sz, node_index); 276 return handle_evacuation_failure_par(old, old_mark); 277 } 278 #endif // !PRODUCT 279 280 // We're going to allocate linearly, so might as well prefetch ahead. 281 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 282 283 const oop obj = oop(obj_ptr); 284 const oop forward_ptr = old->forward_to_atomic(obj, old_mark, memory_order_relaxed); 285 if (forward_ptr == NULL) { 286 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(old), obj_ptr, word_sz); 287 288 const uint young_index = from_region->young_index_in_cset(); 289 290 assert((from_region->is_young() && young_index > 0) || 291 (!from_region->is_young() && young_index == 0), "invariant" ); 292 293 if (dest_attr.is_young()) { 294 if (age < markWord::max_age) { 295 age++; 296 } 297 if (old_mark.has_displaced_mark_helper()) { 298 // In this case, we have to install the mark word first, 299 // otherwise obj looks to be forwarded (the old mark word, 300 // which contains the forward pointer, was copied) 301 obj->set_mark_raw(old_mark); 302 markWord new_mark = old_mark.displaced_mark_helper().set_age(age); 303 old_mark.set_displaced_mark_helper(new_mark); 304 } else { 305 obj->set_mark_raw(old_mark.set_age(age)); 306 } 307 _age_table.add(age, word_sz); 308 } else { 309 obj->set_mark_raw(old_mark); 310 } 311 312 if (G1StringDedup::is_enabled()) { 313 const bool is_from_young = region_attr.is_young(); 314 const bool is_to_young = dest_attr.is_young(); 315 assert(is_from_young == from_region->is_young(), 316 "sanity"); 317 assert(is_to_young == _g1h->heap_region_containing(obj)->is_young(), 318 "sanity"); 319 G1StringDedup::enqueue_from_evacuation(is_from_young, 320 is_to_young, 321 _worker_id, 322 obj); 323 } 324 325 _surviving_young_words[young_index] += word_sz; 326 327 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 328 // We keep track of the next start index in the length field of 329 // the to-space object. The actual length can be found in the 330 // length field of the from-space object. 331 arrayOop(obj)->set_length(0); 332 do_partial_array(PartialArrayScanTask(old)); 333 } else { 334 G1ScanInYoungSetter x(&_scanner, dest_attr.is_young()); 335 obj->oop_iterate_backwards(&_scanner); 336 } 337 return obj; 338 } else { 339 _plab_allocator->undo_allocation(dest_attr, obj_ptr, word_sz, node_index); 340 return forward_ptr; 341 } 342 } 343 344 G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) { 345 assert(worker_id < _n_workers, "out of bounds access"); 346 if (_states[worker_id] == NULL) { 347 _states[worker_id] = 348 new G1ParScanThreadState(_g1h, _rdcqs, worker_id, _young_cset_length, _optional_cset_length); 349 } 350 return _states[worker_id]; 351 } 352 353 const size_t* G1ParScanThreadStateSet::surviving_young_words() const { 354 assert(_flushed, "thread local state from the per thread states should have been flushed"); 355 return _surviving_young_words_total; 356 } 357 358 void G1ParScanThreadStateSet::flush() { 359 assert(!_flushed, "thread local state from the per thread states should be flushed once"); 360 361 for (uint worker_id = 0; worker_id < _n_workers; ++worker_id) { 362 G1ParScanThreadState* pss = _states[worker_id]; 363 364 if (pss == NULL) { 365 continue; 366 } 367 368 G1GCPhaseTimes* p = _g1h->phase_times(); 369 370 // Need to get the following two before the call to G1ParThreadScanState::flush() 371 // because it resets the PLAB allocator where we get this info from. 372 size_t lab_waste_bytes = pss->lab_waste_words() * HeapWordSize; 373 size_t lab_undo_waste_bytes = pss->lab_undo_waste_words() * HeapWordSize; 374 size_t copied_bytes = pss->flush(_surviving_young_words_total) * HeapWordSize; 375 376 p->record_or_add_thread_work_item(G1GCPhaseTimes::MergePSS, worker_id, copied_bytes, G1GCPhaseTimes::MergePSSCopiedBytes); 377 p->record_or_add_thread_work_item(G1GCPhaseTimes::MergePSS, worker_id, lab_waste_bytes, G1GCPhaseTimes::MergePSSLABWasteBytes); 378 p->record_or_add_thread_work_item(G1GCPhaseTimes::MergePSS, worker_id, lab_undo_waste_bytes, G1GCPhaseTimes::MergePSSLABUndoWasteBytes); 379 380 delete pss; 381 _states[worker_id] = NULL; 382 } 383 _flushed = true; 384 } 385 386 void G1ParScanThreadStateSet::record_unused_optional_region(HeapRegion* hr) { 387 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) { 388 G1ParScanThreadState* pss = _states[worker_index]; 389 390 if (pss == NULL) { 391 continue; 392 } 393 394 size_t used_memory = pss->oops_into_optional_region(hr)->used_memory(); 395 _g1h->phase_times()->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanHR, worker_index, used_memory, G1GCPhaseTimes::ScanHRUsedMemory); 396 } 397 } 398 399 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markWord m) { 400 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old)); 401 402 oop forward_ptr = old->forward_to_atomic(old, m, memory_order_relaxed); 403 if (forward_ptr == NULL) { 404 // Forward-to-self succeeded. We are the "owner" of the object. 405 HeapRegion* r = _g1h->heap_region_containing(old); 406 407 if (!r->evacuation_failed()) { 408 r->set_evacuation_failed(true); 409 _g1h->hr_printer()->evac_failure(r); 410 } 411 412 _g1h->preserve_mark_during_evac_failure(_worker_id, old, m); 413 414 G1ScanInYoungSetter x(&_scanner, r->is_young()); 415 old->oop_iterate_backwards(&_scanner); 416 417 return old; 418 } else { 419 // Forward-to-self failed. Either someone else managed to allocate 420 // space for this object (old != forward_ptr) or they beat us in 421 // self-forwarding it (old == forward_ptr). 422 assert(old == forward_ptr || !_g1h->is_in_cset(forward_ptr), 423 "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " " 424 "should not be in the CSet", 425 p2i(old), p2i(forward_ptr)); 426 return forward_ptr; 427 } 428 } 429 G1ParScanThreadStateSet::G1ParScanThreadStateSet(G1CollectedHeap* g1h, 430 G1RedirtyCardsQueueSet* rdcqs, 431 uint n_workers, 432 size_t young_cset_length, 433 size_t optional_cset_length) : 434 _g1h(g1h), 435 _rdcqs(rdcqs), 436 _states(NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC)), 437 _surviving_young_words_total(NEW_C_HEAP_ARRAY(size_t, young_cset_length + 1, mtGC)), 438 _young_cset_length(young_cset_length), 439 _optional_cset_length(optional_cset_length), 440 _n_workers(n_workers), 441 _flushed(false) { 442 for (uint i = 0; i < n_workers; ++i) { 443 _states[i] = NULL; 444 } 445 memset(_surviving_young_words_total, 0, (young_cset_length + 1) * sizeof(size_t)); 446 } 447 448 G1ParScanThreadStateSet::~G1ParScanThreadStateSet() { 449 assert(_flushed, "thread local state from the per thread states should have been flushed"); 450 FREE_C_HEAP_ARRAY(G1ParScanThreadState*, _states); 451 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_total); 452 }