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, uint worker_id, size_t young_cset_length) 41 : _g1h(g1h), 42 _refs(g1h->task_queue(worker_id)), 43 _dcq(&g1h->dirty_card_queue_set()), 44 _ct(g1h->card_table()), 45 _closures(NULL), 46 _plab_allocator(NULL), 47 _age_table(false), 48 // _dest 49 _tenuring_threshold(g1h->g1_policy()->tenuring_threshold()), 50 _scanner(g1h, this), 51 _hash_seed(17), 52 _worker_id(worker_id), 53 _stack_drain_upper_threshold(GCDrainStackTargetSize * 2 + 1), 54 _stack_drain_lower_threshold(GCDrainStackTargetSize), 55 // _surviving_young_words(NULL), 56 // _surviving_young_words_base(NULL), 57 _trim_ticks(), 58 _old_gen_is_full(false) 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 87 // Pass locally gathered statistics to global state. 88 void G1ParScanThreadState::flush(size_t* surviving_young_words) { 89 _dcq.flush(); 90 // Update allocation statistics. 91 _plab_allocator->flush_and_retire_stats(); 92 _g1h->g1_policy()->record_age_table(&_age_table); 93 94 uint length = _g1h->collection_set()->young_region_length(); 95 for (uint region_index = 0; region_index < length; region_index++) { 96 surviving_young_words[region_index] += _surviving_young_words[region_index]; 97 } 98 } 99 100 G1ParScanThreadState::~G1ParScanThreadState() { 101 delete _plab_allocator; 102 delete _closures; 103 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base); 104 } 105 106 void G1ParScanThreadState::waste(size_t& wasted, size_t& undo_wasted) { 107 _plab_allocator->waste(wasted, undo_wasted); 108 } 109 110 #ifdef ASSERT 111 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 112 assert(ref != NULL, "invariant"); 113 assert(UseCompressedOops, "sanity"); 114 assert(!has_partial_array_mask(ref), "ref=" PTR_FORMAT, p2i(ref)); 115 oop p = RawAccess<>::oop_load(ref); 116 assert(_g1h->is_in_g1_reserved(p), 117 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 118 return true; 119 } 120 121 bool G1ParScanThreadState::verify_ref(oop* ref) const { 122 assert(ref != NULL, "invariant"); 123 if (has_partial_array_mask(ref)) { 124 // Must be in the collection set--it's already been copied. 125 oop p = clear_partial_array_mask(ref); 126 assert(_g1h->is_in_cset(p), 127 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 128 } else { 129 oop p = RawAccess<>::oop_load(ref); 130 assert(_g1h->is_in_g1_reserved(p), 131 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 132 } 133 return true; 134 } 135 136 bool G1ParScanThreadState::verify_task(StarTask ref) const { 137 if (ref.is_narrow()) { 138 return verify_ref((narrowOop*) ref); 139 } else { 140 return verify_ref((oop*) ref); 141 } 142 } 143 #endif // ASSERT 144 145 void G1ParScanThreadState::trim_queue() { 146 StarTask ref; 147 do { 148 // Drain the overflow stack first, so other threads can steal. 149 while (_refs->pop_overflow(ref)) { 150 if (!_refs->try_push_to_taskqueue(ref)) { 151 dispatch_reference(ref); 152 } 153 } 154 155 while (_refs->pop_local(ref)) { 156 dispatch_reference(ref); 157 } 158 } while (!_refs->is_empty()); 159 } 160 161 HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state, 162 InCSetState* dest, 163 size_t word_sz, 164 bool previous_plab_refill_failed) { 165 assert(state.is_in_cset_or_humongous(), "Unexpected state: " CSETSTATE_FORMAT, state.value()); 166 assert(dest->is_in_cset_or_humongous(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value()); 167 168 // Right now we only have two types of regions (young / old) so 169 // let's keep the logic here simple. We can generalize it when necessary. 170 if (dest->is_young()) { 171 bool plab_refill_in_old_failed = false; 172 HeapWord* const obj_ptr = _plab_allocator->allocate(InCSetState::Old, 173 word_sz, 174 &plab_refill_in_old_failed); 175 // Make sure that we won't attempt to copy any other objects out 176 // of a survivor region (given that apparently we cannot allocate 177 // any new ones) to avoid coming into this slow path again and again. 178 // Only consider failed PLAB refill here: failed inline allocations are 179 // typically large, so not indicative of remaining space. 180 if (previous_plab_refill_failed) { 181 _tenuring_threshold = 0; 182 } 183 184 if (obj_ptr != NULL) { 185 dest->set_old(); 186 } else { 187 // We just failed to allocate in old gen. The same idea as explained above 188 // for making survivor gen unavailable for allocation applies for old gen. 189 _old_gen_is_full = plab_refill_in_old_failed; 190 } 191 return obj_ptr; 192 } else { 193 _old_gen_is_full = previous_plab_refill_failed; 194 assert(dest->is_old(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value()); 195 // no other space to try. 196 return NULL; 197 } 198 } 199 200 InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) { 201 if (state.is_young()) { 202 age = !m->has_displaced_mark_helper() ? m->age() 203 : m->displaced_mark_helper()->age(); 204 if (age < _tenuring_threshold) { 205 return state; 206 } 207 } 208 return dest(state); 209 } 210 211 void G1ParScanThreadState::report_promotion_event(InCSetState const dest_state, 212 oop const old, size_t word_sz, uint age, 213 HeapWord * const obj_ptr) const { 214 PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_state); 215 if (alloc_buf->contains(obj_ptr)) { 216 _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz, age, 217 dest_state.value() == InCSetState::Old, 218 alloc_buf->word_sz()); 219 } else { 220 _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz, age, 221 dest_state.value() == InCSetState::Old); 222 } 223 } 224 225 oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state, 226 oop const old, 227 markOop const old_mark) { 228 const size_t word_sz = old->size(); 229 HeapRegion* const from_region = _g1h->heap_region_containing(old); 230 // +1 to make the -1 indexes valid... 231 const int young_index = from_region->young_index_in_cset()+1; 232 assert( (from_region->is_young() && young_index > 0) || 233 (!from_region->is_young() && young_index == 0), "invariant" ); 234 235 uint age = 0; 236 InCSetState dest_state = next_state(state, old_mark, age); 237 // The second clause is to prevent premature evacuation failure in case there 238 // is still space in survivor, but old gen is full. 239 if (_old_gen_is_full && dest_state.is_old()) { 240 return handle_evacuation_failure_par(old, old_mark); 241 } 242 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_state, word_sz); 243 244 // PLAB allocations should succeed most of the time, so we'll 245 // normally check against NULL once and that's it. 246 if (obj_ptr == NULL) { 247 bool plab_refill_failed = false; 248 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(dest_state, word_sz, &plab_refill_failed); 249 if (obj_ptr == NULL) { 250 obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, plab_refill_failed); 251 if (obj_ptr == NULL) { 252 // This will either forward-to-self, or detect that someone else has 253 // installed a forwarding pointer. 254 return handle_evacuation_failure_par(old, old_mark); 255 } 256 } 257 if (_g1h->_gc_tracer_stw->should_report_promotion_events()) { 258 // The events are checked individually as part of the actual commit 259 report_promotion_event(dest_state, old, word_sz, age, obj_ptr); 260 } 261 } 262 263 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded"); 264 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap"); 265 266 #ifndef PRODUCT 267 // Should this evacuation fail? 268 if (_g1h->evacuation_should_fail()) { 269 // Doing this after all the allocation attempts also tests the 270 // undo_allocation() method too. 271 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz); 272 return handle_evacuation_failure_par(old, old_mark); 273 } 274 #endif // !PRODUCT 275 276 // We're going to allocate linearly, so might as well prefetch ahead. 277 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 278 279 const oop obj = oop(obj_ptr); 280 const oop forward_ptr = old->forward_to_atomic(obj); 281 if (forward_ptr == NULL) { 282 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); 283 284 if (dest_state.is_young()) { 285 if (age < markOopDesc::max_age) { 286 age++; 287 } 288 if (old_mark->has_displaced_mark_helper()) { 289 // In this case, we have to install the mark word first, 290 // otherwise obj looks to be forwarded (the old mark word, 291 // which contains the forward pointer, was copied) 292 obj->set_mark_raw(old_mark); 293 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age); 294 old_mark->set_displaced_mark_helper(new_mark); 295 } else { 296 obj->set_mark_raw(old_mark->set_age(age)); 297 } 298 _age_table.add(age, word_sz); 299 } else { 300 obj->set_mark_raw(old_mark); 301 } 302 303 if (G1StringDedup::is_enabled()) { 304 const bool is_from_young = state.is_young(); 305 const bool is_to_young = dest_state.is_young(); 306 assert(is_from_young == _g1h->heap_region_containing(old)->is_young(), 307 "sanity"); 308 assert(is_to_young == _g1h->heap_region_containing(obj)->is_young(), 309 "sanity"); 310 G1StringDedup::enqueue_from_evacuation(is_from_young, 311 is_to_young, 312 _worker_id, 313 obj); 314 } 315 316 _surviving_young_words[young_index] += word_sz; 317 318 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 319 // We keep track of the next start index in the length field of 320 // the to-space object. The actual length can be found in the 321 // length field of the from-space object. 322 arrayOop(obj)->set_length(0); 323 oop* old_p = set_partial_array_mask(old); 324 do_oop_partial_array(old_p); 325 } else { 326 HeapRegion* const to_region = _g1h->heap_region_containing(obj_ptr); 327 _scanner.set_region(to_region); 328 obj->oop_iterate_backwards(&_scanner); 329 } 330 return obj; 331 } else { 332 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz); 333 return forward_ptr; 334 } 335 } 336 337 G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) { 338 assert(worker_id < _n_workers, "out of bounds access"); 339 if (_states[worker_id] == NULL) { 340 _states[worker_id] = new G1ParScanThreadState(_g1h, worker_id, _young_cset_length); 341 } 342 return _states[worker_id]; 343 } 344 345 const size_t* G1ParScanThreadStateSet::surviving_young_words() const { 346 assert(_flushed, "thread local state from the per thread states should have been flushed"); 347 return _surviving_young_words_total; 348 } 349 350 void G1ParScanThreadStateSet::flush() { 351 assert(!_flushed, "thread local state from the per thread states should be flushed once"); 352 353 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) { 354 G1ParScanThreadState* pss = _states[worker_index]; 355 356 if (pss == NULL) { 357 continue; 358 } 359 360 pss->flush(_surviving_young_words_total); 361 delete pss; 362 _states[worker_index] = NULL; 363 } 364 _flushed = true; 365 } 366 367 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop m) { 368 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old)); 369 370 oop forward_ptr = old->forward_to_atomic(old); 371 if (forward_ptr == NULL) { 372 // Forward-to-self succeeded. We are the "owner" of the object. 373 HeapRegion* r = _g1h->heap_region_containing(old); 374 375 if (!r->evacuation_failed()) { 376 r->set_evacuation_failed(true); 377 _g1h->hr_printer()->evac_failure(r); 378 } 379 380 _g1h->preserve_mark_during_evac_failure(_worker_id, old, m); 381 382 _scanner.set_region(r); 383 old->oop_iterate_backwards(&_scanner); 384 385 return old; 386 } else { 387 // Forward-to-self failed. Either someone else managed to allocate 388 // space for this object (old != forward_ptr) or they beat us in 389 // self-forwarding it (old == forward_ptr). 390 assert(old == forward_ptr || !_g1h->is_in_cset(forward_ptr), 391 "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " " 392 "should not be in the CSet", 393 p2i(old), p2i(forward_ptr)); 394 return forward_ptr; 395 } 396 } 397 G1ParScanThreadStateSet::G1ParScanThreadStateSet(G1CollectedHeap* g1h, uint n_workers, size_t young_cset_length) : 398 _g1h(g1h), 399 _states(NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC)), 400 _surviving_young_words_total(NEW_C_HEAP_ARRAY(size_t, young_cset_length, mtGC)), 401 _young_cset_length(young_cset_length), 402 _n_workers(n_workers), 403 _flushed(false) { 404 for (uint i = 0; i < n_workers; ++i) { 405 _states[i] = NULL; 406 } 407 memset(_surviving_young_words_total, 0, young_cset_length * sizeof(size_t)); 408 } 409 410 G1ParScanThreadStateSet::~G1ParScanThreadStateSet() { 411 assert(_flushed, "thread local state from the per thread states should have been flushed"); 412 FREE_C_HEAP_ARRAY(G1ParScanThreadState*, _states); 413 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_total); 414 }