1 /* 2 * Copyright (c) 2014, 2017, 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/taskqueue.inline.hpp" 34 #include "oops/oop.inline.hpp" 35 #include "runtime/prefetch.inline.hpp" 36 37 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint worker_id, size_t young_cset_length) 38 : _g1h(g1h), 39 _refs(g1h->task_queue(worker_id)), 40 _dcq(&g1h->dirty_card_queue_set()), 41 _ct(g1h->g1_card_table()), 42 _closures(NULL), 43 _hash_seed(17), 44 _worker_id(worker_id), 45 _tenuring_threshold(g1h->g1_policy()->tenuring_threshold()), 46 _age_table(false), 47 _scanner(g1h, this), 48 _old_gen_is_full(false) 49 { 50 // we allocate G1YoungSurvRateNumRegions plus one entries, since 51 // we "sacrifice" entry 0 to keep track of surviving bytes for 52 // non-young regions (where the age is -1) 53 // We also add a few elements at the beginning and at the end in 54 // an attempt to eliminate cache contention 55 size_t real_length = 1 + young_cset_length; 56 size_t array_length = PADDING_ELEM_NUM + 57 real_length + 58 PADDING_ELEM_NUM; 59 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); 60 if (_surviving_young_words_base == NULL) 61 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR, 62 "Not enough space for young surv histo."); 63 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 64 memset(_surviving_young_words, 0, real_length * sizeof(size_t)); 65 66 _plab_allocator = G1PLABAllocator::create_allocator(_g1h->allocator()); 67 68 _dest[InCSetState::NotInCSet] = InCSetState::NotInCSet; 69 // The dest for Young is used when the objects are aged enough to 70 // need to be moved to the next space. 71 _dest[InCSetState::Young] = InCSetState::Old; 72 _dest[InCSetState::Old] = InCSetState::Old; 73 74 _closures = G1EvacuationRootClosures::create_root_closures(this, _g1h); 75 } 76 77 // Pass locally gathered statistics to global state. 78 void G1ParScanThreadState::flush(size_t* surviving_young_words) { 79 _dcq.flush(); 80 // Update allocation statistics. 81 _plab_allocator->flush_and_retire_stats(); 82 _g1h->g1_policy()->record_age_table(&_age_table); 83 84 uint length = _g1h->collection_set()->young_region_length(); 85 for (uint region_index = 0; region_index < length; region_index++) { 86 surviving_young_words[region_index] += _surviving_young_words[region_index]; 87 } 88 } 89 90 G1ParScanThreadState::~G1ParScanThreadState() { 91 delete _plab_allocator; 92 delete _closures; 93 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base); 94 } 95 96 void G1ParScanThreadState::waste(size_t& wasted, size_t& undo_wasted) { 97 _plab_allocator->waste(wasted, undo_wasted); 98 } 99 100 #ifdef ASSERT 101 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 102 assert(ref != NULL, "invariant"); 103 assert(UseCompressedOops, "sanity"); 104 assert(!has_partial_array_mask(ref), "ref=" PTR_FORMAT, p2i(ref)); 105 oop p = oopDesc::load_decode_heap_oop(ref); 106 assert(_g1h->is_in_g1_reserved(p), 107 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 108 return true; 109 } 110 111 bool G1ParScanThreadState::verify_ref(oop* ref) const { 112 assert(ref != NULL, "invariant"); 113 if (has_partial_array_mask(ref)) { 114 // Must be in the collection set--it's already been copied. 115 oop p = clear_partial_array_mask(ref); 116 assert(_g1h->is_in_cset(p), 117 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 118 } else { 119 oop p = oopDesc::load_decode_heap_oop(ref); 120 assert(_g1h->is_in_g1_reserved(p), 121 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 122 } 123 return true; 124 } 125 126 bool G1ParScanThreadState::verify_task(StarTask ref) const { 127 if (ref.is_narrow()) { 128 return verify_ref((narrowOop*) ref); 129 } else { 130 return verify_ref((oop*) ref); 131 } 132 } 133 #endif // ASSERT 134 135 void G1ParScanThreadState::trim_queue() { 136 StarTask ref; 137 do { 138 // Drain the overflow stack first, so other threads can steal. 139 while (_refs->pop_overflow(ref)) { 140 if (!_refs->try_push_to_taskqueue(ref)) { 141 dispatch_reference(ref); 142 } 143 } 144 145 while (_refs->pop_local(ref)) { 146 dispatch_reference(ref); 147 } 148 } while (!_refs->is_empty()); 149 } 150 151 HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state, 152 InCSetState* dest, 153 size_t word_sz, 154 AllocationContext_t const context, 155 bool previous_plab_refill_failed) { 156 assert(state.is_in_cset_or_humongous(), "Unexpected state: " CSETSTATE_FORMAT, state.value()); 157 assert(dest->is_in_cset_or_humongous(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value()); 158 159 // Right now we only have two types of regions (young / old) so 160 // let's keep the logic here simple. We can generalize it when necessary. 161 if (dest->is_young()) { 162 bool plab_refill_in_old_failed = false; 163 HeapWord* const obj_ptr = _plab_allocator->allocate(InCSetState::Old, 164 word_sz, 165 context, 166 &plab_refill_in_old_failed); 167 // Make sure that we won't attempt to copy any other objects out 168 // of a survivor region (given that apparently we cannot allocate 169 // any new ones) to avoid coming into this slow path again and again. 170 // Only consider failed PLAB refill here: failed inline allocations are 171 // typically large, so not indicative of remaining space. 172 if (previous_plab_refill_failed) { 173 _tenuring_threshold = 0; 174 } 175 176 if (obj_ptr != NULL) { 177 dest->set_old(); 178 } else { 179 // We just failed to allocate in old gen. The same idea as explained above 180 // for making survivor gen unavailable for allocation applies for old gen. 181 _old_gen_is_full = plab_refill_in_old_failed; 182 } 183 return obj_ptr; 184 } else { 185 _old_gen_is_full = previous_plab_refill_failed; 186 assert(dest->is_old(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value()); 187 // no other space to try. 188 return NULL; 189 } 190 } 191 192 InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) { 193 if (state.is_young()) { 194 age = !m->has_displaced_mark_helper() ? m->age() 195 : m->displaced_mark_helper()->age(); 196 if (age < _tenuring_threshold) { 197 return state; 198 } 199 } 200 return dest(state); 201 } 202 203 void G1ParScanThreadState::report_promotion_event(InCSetState const dest_state, 204 oop const old, size_t word_sz, uint age, 205 HeapWord * const obj_ptr, 206 const AllocationContext_t context) const { 207 G1PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_state, context); 208 if (alloc_buf->contains(obj_ptr)) { 209 _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz, age, 210 dest_state.value() == InCSetState::Old, 211 alloc_buf->word_sz()); 212 } else { 213 _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz, age, 214 dest_state.value() == InCSetState::Old); 215 } 216 } 217 218 oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state, 219 oop const old, 220 markOop const old_mark) { 221 const size_t word_sz = old->size(); 222 HeapRegion* const from_region = _g1h->heap_region_containing(old); 223 // +1 to make the -1 indexes valid... 224 const int young_index = from_region->young_index_in_cset()+1; 225 assert( (from_region->is_young() && young_index > 0) || 226 (!from_region->is_young() && young_index == 0), "invariant" ); 227 const AllocationContext_t context = from_region->allocation_context(); 228 229 uint age = 0; 230 InCSetState dest_state = next_state(state, old_mark, age); 231 // The second clause is to prevent premature evacuation failure in case there 232 // is still space in survivor, but old gen is full. 233 if (_old_gen_is_full && dest_state.is_old()) { 234 return handle_evacuation_failure_par(old, old_mark); 235 } 236 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_state, word_sz, context); 237 238 // PLAB allocations should succeed most of the time, so we'll 239 // normally check against NULL once and that's it. 240 if (obj_ptr == NULL) { 241 bool plab_refill_failed = false; 242 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(dest_state, word_sz, context, &plab_refill_failed); 243 if (obj_ptr == NULL) { 244 obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, context, plab_refill_failed); 245 if (obj_ptr == NULL) { 246 // This will either forward-to-self, or detect that someone else has 247 // installed a forwarding pointer. 248 return handle_evacuation_failure_par(old, old_mark); 249 } 250 } 251 if (_g1h->_gc_tracer_stw->should_report_promotion_events()) { 252 // The events are checked individually as part of the actual commit 253 report_promotion_event(dest_state, old, word_sz, age, obj_ptr, context); 254 } 255 } 256 257 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded"); 258 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap"); 259 260 #ifndef PRODUCT 261 // Should this evacuation fail? 262 if (_g1h->evacuation_should_fail()) { 263 // Doing this after all the allocation attempts also tests the 264 // undo_allocation() method too. 265 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context); 266 return handle_evacuation_failure_par(old, old_mark); 267 } 268 #endif // !PRODUCT 269 270 // We're going to allocate linearly, so might as well prefetch ahead. 271 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 272 273 const oop obj = oop(obj_ptr); 274 const oop forward_ptr = old->forward_to_atomic(obj); 275 if (forward_ptr == NULL) { 276 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); 277 278 if (dest_state.is_young()) { 279 if (age < markOopDesc::max_age) { 280 age++; 281 } 282 if (old_mark->has_displaced_mark_helper()) { 283 // In this case, we have to install the mark word first, 284 // otherwise obj looks to be forwarded (the old mark word, 285 // which contains the forward pointer, was copied) 286 obj->set_mark(old_mark); 287 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age); 288 old_mark->set_displaced_mark_helper(new_mark); 289 } else { 290 obj->set_mark(old_mark->set_age(age)); 291 } 292 _age_table.add(age, word_sz); 293 } else { 294 obj->set_mark(old_mark); 295 } 296 297 if (G1StringDedup::is_enabled()) { 298 const bool is_from_young = state.is_young(); 299 const bool is_to_young = dest_state.is_young(); 300 assert(is_from_young == _g1h->heap_region_containing(old)->is_young(), 301 "sanity"); 302 assert(is_to_young == _g1h->heap_region_containing(obj)->is_young(), 303 "sanity"); 304 G1StringDedup::enqueue_from_evacuation(is_from_young, 305 is_to_young, 306 _worker_id, 307 obj); 308 } 309 310 _surviving_young_words[young_index] += word_sz; 311 312 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 313 // We keep track of the next start index in the length field of 314 // the to-space object. The actual length can be found in the 315 // length field of the from-space object. 316 arrayOop(obj)->set_length(0); 317 oop* old_p = set_partial_array_mask(old); 318 push_on_queue(old_p); 319 } else { 320 HeapRegion* const to_region = _g1h->heap_region_containing(obj_ptr); 321 _scanner.set_region(to_region); 322 obj->oop_iterate_backwards(&_scanner); 323 } 324 return obj; 325 } else { 326 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context); 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] = new_par_scan_state(worker_id, _young_cset_length); 335 } 336 return _states[worker_id]; 337 } 338 339 void G1ParScanThreadStateSet::add_cards_scanned(uint worker_id, size_t cards_scanned) { 340 assert(worker_id < _n_workers, "out of bounds access"); 341 _cards_scanned[worker_id] += cards_scanned; 342 } 343 344 size_t G1ParScanThreadStateSet::total_cards_scanned() const { 345 assert(_flushed, "thread local state from the per thread states should have been flushed"); 346 return _total_cards_scanned; 347 } 348 349 const size_t* G1ParScanThreadStateSet::surviving_young_words() const { 350 assert(_flushed, "thread local state from the per thread states should have been flushed"); 351 return _surviving_young_words_total; 352 } 353 354 void G1ParScanThreadStateSet::flush() { 355 assert(!_flushed, "thread local state from the per thread states should be flushed once"); 356 assert(_total_cards_scanned == 0, "should have been cleared"); 357 358 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) { 359 G1ParScanThreadState* pss = _states[worker_index]; 360 361 if (pss == NULL) { 362 continue; 363 } 364 365 _total_cards_scanned += _cards_scanned[worker_index]; 366 367 pss->flush(_surviving_young_words_total); 368 delete pss; 369 _states[worker_index] = NULL; 370 } 371 _flushed = true; 372 } 373 374 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop m) { 375 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old)); 376 377 oop forward_ptr = old->forward_to_atomic(old); 378 if (forward_ptr == NULL) { 379 // Forward-to-self succeeded. We are the "owner" of the object. 380 HeapRegion* r = _g1h->heap_region_containing(old); 381 382 if (!r->evacuation_failed()) { 383 r->set_evacuation_failed(true); 384 _g1h->hr_printer()->evac_failure(r); 385 } 386 387 _g1h->preserve_mark_during_evac_failure(_worker_id, old, m); 388 389 _scanner.set_region(r); 390 old->oop_iterate_backwards(&_scanner); 391 392 return old; 393 } else { 394 // Forward-to-self failed. Either someone else managed to allocate 395 // space for this object (old != forward_ptr) or they beat us in 396 // self-forwarding it (old == forward_ptr). 397 assert(old == forward_ptr || !_g1h->is_in_cset(forward_ptr), 398 "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " " 399 "should not be in the CSet", 400 p2i(old), p2i(forward_ptr)); 401 return forward_ptr; 402 } 403 }