1 /* 2 * Copyright (c) 2014, 2018, 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/shared/gcTrace.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 uint worker_id, 42 size_t young_cset_length, 43 size_t optional_cset_length) 44 : _g1h(g1h), 45 _refs(g1h->task_queue(worker_id)), 46 _dcq(&g1h->dirty_card_queue_set()), 47 _ct(g1h->card_table()), 48 _closures(NULL), 49 _plab_allocator(NULL), 50 _age_table(false), 51 _tenuring_threshold(g1h->g1_policy()->tenuring_threshold()), 52 _scanner(g1h, this), 53 _worker_id(worker_id), 54 _stack_trim_upper_threshold(GCDrainStackTargetSize * 2 + 1), 55 _stack_trim_lower_threshold(GCDrainStackTargetSize), 56 _trim_ticks(), 57 _old_gen_is_full(false), 58 _num_optional_regions(optional_cset_length) 59 { 60 // we allocate G1YoungSurvRateNumRegions plus one entries, since 61 // we "sacrifice" entry 0 to keep track of surviving bytes for 62 // non-young regions (where the age is -1) 63 // We also add a few elements at the beginning and at the end in 64 // an attempt to eliminate cache contention 65 size_t real_length = 1 + young_cset_length; 66 size_t array_length = PADDING_ELEM_NUM + 67 real_length + 68 PADDING_ELEM_NUM; 69 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); 70 if (_surviving_young_words_base == NULL) 71 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR, 72 "Not enough space for young surv histo."); 73 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 74 memset(_surviving_young_words, 0, real_length * sizeof(size_t)); 75 76 _plab_allocator = new G1PLABAllocator(_g1h->allocator()); 77 78 _dest[InCSetState::NotInCSet] = InCSetState::NotInCSet; 79 // The dest for Young is used when the objects are aged enough to 80 // need to be moved to the next space. 81 _dest[InCSetState::Young] = InCSetState::Old; 82 _dest[InCSetState::Old] = InCSetState::Old; 83 84 _closures = G1EvacuationRootClosures::create_root_closures(this, _g1h); 85 86 _oops_into_optional_regions = new G1OopStarChunkedList[_num_optional_regions]; 87 } 88 89 // Pass locally gathered statistics to global state. 90 void G1ParScanThreadState::flush(size_t* surviving_young_words) { 91 _dcq.flush(); 92 // Update allocation statistics. 93 _plab_allocator->flush_and_retire_stats(); 94 _g1h->g1_policy()->record_age_table(&_age_table); 95 96 uint length = _g1h->collection_set()->young_region_length(); 97 for (uint region_index = 0; region_index < length; region_index++) { 98 surviving_young_words[region_index] += _surviving_young_words[region_index]; 99 } 100 } 101 102 G1ParScanThreadState::~G1ParScanThreadState() { 103 delete _plab_allocator; 104 delete _closures; 105 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base); 106 delete[] _oops_into_optional_regions; 107 } 108 109 void G1ParScanThreadState::waste(size_t& wasted, size_t& undo_wasted) { 110 _plab_allocator->waste(wasted, undo_wasted); 111 } 112 113 #ifdef ASSERT 114 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 115 assert(ref != NULL, "invariant"); 116 assert(UseCompressedOops, "sanity"); 117 assert(!has_partial_array_mask(ref), "ref=" PTR_FORMAT, p2i(ref)); 118 oop p = RawAccess<>::oop_load(ref); 119 assert(_g1h->is_in_g1_reserved(p), 120 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 121 return true; 122 } 123 124 bool G1ParScanThreadState::verify_ref(oop* ref) const { 125 assert(ref != NULL, "invariant"); 126 if (has_partial_array_mask(ref)) { 127 // Must be in the collection set--it's already been copied. 128 oop p = clear_partial_array_mask(ref); 129 assert(_g1h->is_in_cset(p), 130 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 131 } else { 132 oop p = RawAccess<>::oop_load(ref); 133 assert(_g1h->is_in_g1_reserved(p), 134 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 135 } 136 return true; 137 } 138 139 bool G1ParScanThreadState::verify_task(StarTask ref) const { 140 if (ref.is_narrow()) { 141 return verify_ref((narrowOop*) ref); 142 } else { 143 return verify_ref((oop*) ref); 144 } 145 } 146 #endif // ASSERT 147 148 void G1ParScanThreadState::trim_queue() { 149 StarTask ref; 150 do { 151 // Fully drain the queue. 152 trim_queue_to_threshold(0); 153 } while (!_refs->is_empty()); 154 } 155 156 HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state, 157 InCSetState* dest, 158 size_t word_sz, 159 bool previous_plab_refill_failed) { 160 assert(state.is_in_cset_or_humongous(), "Unexpected state: " CSETSTATE_FORMAT, state.value()); 161 assert(dest->is_in_cset_or_humongous(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value()); 162 163 // Right now we only have two types of regions (young / old) so 164 // let's keep the logic here simple. We can generalize it when necessary. 165 if (dest->is_young()) { 166 bool plab_refill_in_old_failed = false; 167 HeapWord* const obj_ptr = _plab_allocator->allocate(InCSetState::Old, 168 word_sz, 169 &plab_refill_in_old_failed); 170 // Make sure that we won't attempt to copy any other objects out 171 // of a survivor region (given that apparently we cannot allocate 172 // any new ones) to avoid coming into this slow path again and again. 173 // Only consider failed PLAB refill here: failed inline allocations are 174 // typically large, so not indicative of remaining space. 175 if (previous_plab_refill_failed) { 176 _tenuring_threshold = 0; 177 } 178 179 if (obj_ptr != NULL) { 180 dest->set_old(); 181 } else { 182 // We just failed to allocate in old gen. The same idea as explained above 183 // for making survivor gen unavailable for allocation applies for old gen. 184 _old_gen_is_full = plab_refill_in_old_failed; 185 } 186 return obj_ptr; 187 } else { 188 _old_gen_is_full = previous_plab_refill_failed; 189 assert(dest->is_old(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value()); 190 // no other space to try. 191 return NULL; 192 } 193 } 194 195 InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) { 196 if (state.is_young()) { 197 age = !m->has_displaced_mark_helper() ? m->age() 198 : m->displaced_mark_helper()->age(); 199 if (age < _tenuring_threshold) { 200 return state; 201 } 202 } 203 return dest(state); 204 } 205 206 void G1ParScanThreadState::report_promotion_event(InCSetState const dest_state, 207 oop const old, size_t word_sz, uint age, 208 HeapWord * const obj_ptr) const { 209 PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_state); 210 if (alloc_buf->contains(obj_ptr)) { 211 _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz * HeapWordSize, age, 212 dest_state.value() == InCSetState::Old, 213 alloc_buf->word_sz() * HeapWordSize); 214 } else { 215 _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz * HeapWordSize, age, 216 dest_state.value() == InCSetState::Old); 217 } 218 } 219 220 oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state, 221 oop const old, 222 markOop const old_mark) { 223 const size_t word_sz = old->size(); 224 HeapRegion* const from_region = _g1h->heap_region_containing(old); 225 // +1 to make the -1 indexes valid... 226 const int young_index = from_region->young_index_in_cset()+1; 227 assert( (from_region->is_young() && young_index > 0) || 228 (!from_region->is_young() && young_index == 0), "invariant" ); 229 230 uint age = 0; 231 InCSetState dest_state = next_state(state, old_mark, age); 232 // The second clause is to prevent premature evacuation failure in case there 233 // is still space in survivor, but old gen is full. 234 if (_old_gen_is_full && dest_state.is_old()) { 235 return handle_evacuation_failure_par(old, old_mark); 236 } 237 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_state, word_sz); 238 239 // PLAB allocations should succeed most of the time, so we'll 240 // normally check against NULL once and that's it. 241 if (obj_ptr == NULL) { 242 bool plab_refill_failed = false; 243 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(dest_state, word_sz, &plab_refill_failed); 244 if (obj_ptr == NULL) { 245 obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, plab_refill_failed); 246 if (obj_ptr == NULL) { 247 // This will either forward-to-self, or detect that someone else has 248 // installed a forwarding pointer. 249 return handle_evacuation_failure_par(old, old_mark); 250 } 251 } 252 if (_g1h->_gc_tracer_stw->should_report_promotion_events()) { 253 // The events are checked individually as part of the actual commit 254 report_promotion_event(dest_state, old, word_sz, age, obj_ptr); 255 } 256 } 257 258 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded"); 259 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap"); 260 261 #ifndef PRODUCT 262 // Should this evacuation fail? 263 if (_g1h->evacuation_should_fail()) { 264 // Doing this after all the allocation attempts also tests the 265 // undo_allocation() method too. 266 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz); 267 return handle_evacuation_failure_par(old, old_mark); 268 } 269 #endif // !PRODUCT 270 271 // We're going to allocate linearly, so might as well prefetch ahead. 272 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 273 274 const oop obj = oop(obj_ptr); 275 const oop forward_ptr = old->forward_to_atomic(obj, old_mark, memory_order_relaxed); 276 if (forward_ptr == NULL) { 277 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); 278 279 if (dest_state.is_young()) { 280 if (age < markOopDesc::max_age) { 281 age++; 282 } 283 if (old_mark->has_displaced_mark_helper()) { 284 // In this case, we have to install the mark word first, 285 // otherwise obj looks to be forwarded (the old mark word, 286 // which contains the forward pointer, was copied) 287 obj->set_mark_raw(old_mark); 288 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age); 289 old_mark->set_displaced_mark_helper(new_mark); 290 } else { 291 obj->set_mark_raw(old_mark->set_age(age)); 292 } 293 _age_table.add(age, word_sz); 294 } else { 295 obj->set_mark_raw(old_mark); 296 } 297 298 if (G1StringDedup::is_enabled()) { 299 const bool is_from_young = state.is_young(); 300 const bool is_to_young = dest_state.is_young(); 301 assert(is_from_young == _g1h->heap_region_containing(old)->is_young(), 302 "sanity"); 303 assert(is_to_young == _g1h->heap_region_containing(obj)->is_young(), 304 "sanity"); 305 G1StringDedup::enqueue_from_evacuation(is_from_young, 306 is_to_young, 307 _worker_id, 308 obj); 309 } 310 311 _surviving_young_words[young_index] += word_sz; 312 313 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 314 // We keep track of the next start index in the length field of 315 // the to-space object. The actual length can be found in the 316 // length field of the from-space object. 317 arrayOop(obj)->set_length(0); 318 oop* old_p = set_partial_array_mask(old); 319 do_oop_partial_array(old_p); 320 } else { 321 G1ScanInYoungSetter x(&_scanner, dest_state.is_young()); 322 obj->oop_iterate_backwards(&_scanner); 323 } 324 return obj; 325 } else { 326 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz); 327 return forward_ptr; 328 } 329 } 330 331 G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) { 332 assert(worker_id < _n_workers, "out of bounds access"); 333 if (_states[worker_id] == NULL) { 334 _states[worker_id] = 335 new G1ParScanThreadState(_g1h, worker_id, _young_cset_length, _optional_cset_length); 336 } 337 return _states[worker_id]; 338 } 339 340 const size_t* G1ParScanThreadStateSet::surviving_young_words() const { 341 assert(_flushed, "thread local state from the per thread states should have been flushed"); 342 return _surviving_young_words_total; 343 } 344 345 void G1ParScanThreadStateSet::flush() { 346 assert(!_flushed, "thread local state from the per thread states should be flushed once"); 347 348 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) { 349 G1ParScanThreadState* pss = _states[worker_index]; 350 351 if (pss == NULL) { 352 continue; 353 } 354 355 pss->flush(_surviving_young_words_total); 356 delete pss; 357 _states[worker_index] = NULL; 358 } 359 _flushed = true; 360 } 361 362 void G1ParScanThreadStateSet::record_unused_optional_region(HeapRegion* hr) { 363 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) { 364 G1ParScanThreadState* pss = _states[worker_index]; 365 366 if (pss == NULL) { 367 continue; 368 } 369 370 size_t used_memory = pss->oops_into_optional_region(hr)->used_memory(); 371 _g1h->g1_policy()->phase_times()->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_index, used_memory, G1GCPhaseTimes::OptCSetUsedMemory); 372 } 373 } 374 375 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop m) { 376 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old)); 377 378 oop forward_ptr = old->forward_to_atomic(old, m, memory_order_relaxed); 379 if (forward_ptr == NULL) { 380 // Forward-to-self succeeded. We are the "owner" of the object. 381 HeapRegion* r = _g1h->heap_region_containing(old); 382 383 if (!r->evacuation_failed()) { 384 r->set_evacuation_failed(true); 385 _g1h->hr_printer()->evac_failure(r); 386 } 387 388 _g1h->preserve_mark_during_evac_failure(_worker_id, old, m); 389 390 G1ScanInYoungSetter x(&_scanner, r->is_young()); 391 old->oop_iterate_backwards(&_scanner); 392 393 return old; 394 } else { 395 // Forward-to-self failed. Either someone else managed to allocate 396 // space for this object (old != forward_ptr) or they beat us in 397 // self-forwarding it (old == forward_ptr). 398 assert(old == forward_ptr || !_g1h->is_in_cset(forward_ptr), 399 "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " " 400 "should not be in the CSet", 401 p2i(old), p2i(forward_ptr)); 402 return forward_ptr; 403 } 404 } 405 G1ParScanThreadStateSet::G1ParScanThreadStateSet(G1CollectedHeap* g1h, 406 uint n_workers, 407 size_t young_cset_length, 408 size_t optional_cset_length) : 409 _g1h(g1h), 410 _states(NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC)), 411 _surviving_young_words_total(NEW_C_HEAP_ARRAY(size_t, young_cset_length, mtGC)), 412 _young_cset_length(young_cset_length), 413 _optional_cset_length(optional_cset_length), 414 _n_workers(n_workers), 415 _flushed(false) { 416 for (uint i = 0; i < n_workers; ++i) { 417 _states[i] = NULL; 418 } 419 memset(_surviving_young_words_total, 0, young_cset_length * sizeof(size_t)); 420 } 421 422 G1ParScanThreadStateSet::~G1ParScanThreadStateSet() { 423 assert(_flushed, "thread local state from the per thread states should have been flushed"); 424 FREE_C_HEAP_ARRAY(G1ParScanThreadState*, _states); 425 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_total); 426 }