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/oop.inline.hpp" 37 #include "runtime/prefetch.inline.hpp" 38 39 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint worker_id, size_t young_cset_length) 40 : _g1h(g1h), 41 _refs(g1h->task_queue(worker_id)), 42 _dcq(&g1h->dirty_card_queue_set()), 43 _ct(g1h->card_table()), 44 _closures(NULL), 45 _hash_seed(17), 46 _worker_id(worker_id), 47 _tenuring_threshold(g1h->g1_policy()->tenuring_threshold()), 48 _age_table(false), 49 _scanner(g1h, this), 50 _old_gen_is_full(false) 51 { 52 // we allocate G1YoungSurvRateNumRegions plus one entries, since 53 // we "sacrifice" entry 0 to keep track of surviving bytes for 54 // non-young regions (where the age is -1) 55 // We also add a few elements at the beginning and at the end in 56 // an attempt to eliminate cache contention 57 size_t real_length = 1 + young_cset_length; 58 size_t array_length = PADDING_ELEM_NUM + 59 real_length + 60 PADDING_ELEM_NUM; 61 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); 62 if (_surviving_young_words_base == NULL) 63 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR, 64 "Not enough space for young surv histo."); 65 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 66 memset(_surviving_young_words, 0, real_length * sizeof(size_t)); 67 68 _plab_allocator = new G1DefaultPLABAllocator(_g1h->allocator()); 69 70 _dest[InCSetState::NotInCSet] = InCSetState::NotInCSet; 71 // The dest for Young is used when the objects are aged enough to 72 // need to be moved to the next space. 73 _dest[InCSetState::Young] = InCSetState::Old; 74 _dest[InCSetState::Old] = InCSetState::Old; 75 76 _closures = G1EvacuationRootClosures::create_root_closures(this, _g1h); 77 } 78 79 // Pass locally gathered statistics to global state. 80 void G1ParScanThreadState::flush(size_t* surviving_young_words) { 81 _dcq.flush(); 82 // Update allocation statistics. 83 _plab_allocator->flush_and_retire_stats(); 84 _g1h->g1_policy()->record_age_table(&_age_table); 85 86 uint length = _g1h->collection_set()->young_region_length(); 87 for (uint region_index = 0; region_index < length; region_index++) { 88 surviving_young_words[region_index] += _surviving_young_words[region_index]; 89 } 90 } 91 92 G1ParScanThreadState::~G1ParScanThreadState() { 93 delete _plab_allocator; 94 delete _closures; 95 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base); 96 } 97 98 void G1ParScanThreadState::waste(size_t& wasted, size_t& undo_wasted) { 99 _plab_allocator->waste(wasted, undo_wasted); 100 } 101 102 #ifdef ASSERT 103 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 104 assert(ref != NULL, "invariant"); 105 assert(UseCompressedOops, "sanity"); 106 assert(!has_partial_array_mask(ref), "ref=" PTR_FORMAT, p2i(ref)); 107 oop p = oopDesc::load_decode_heap_oop(ref); 108 assert(_g1h->is_in_g1_reserved(p), 109 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 110 return true; 111 } 112 113 bool G1ParScanThreadState::verify_ref(oop* ref) const { 114 assert(ref != NULL, "invariant"); 115 if (has_partial_array_mask(ref)) { 116 // Must be in the collection set--it's already been copied. 117 oop p = clear_partial_array_mask(ref); 118 assert(_g1h->is_in_cset(p), 119 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 120 } else { 121 oop p = oopDesc::load_decode_heap_oop(ref); 122 assert(_g1h->is_in_g1_reserved(p), 123 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 124 } 125 return true; 126 } 127 128 bool G1ParScanThreadState::verify_task(StarTask ref) const { 129 if (ref.is_narrow()) { 130 return verify_ref((narrowOop*) ref); 131 } else { 132 return verify_ref((oop*) ref); 133 } 134 } 135 #endif // ASSERT 136 137 void G1ParScanThreadState::trim_queue() { 138 StarTask ref; 139 do { 140 // Drain the overflow stack first, so other threads can steal. 141 while (_refs->pop_overflow(ref)) { 142 if (!_refs->try_push_to_taskqueue(ref)) { 143 dispatch_reference(ref); 144 } 145 } 146 147 while (_refs->pop_local(ref)) { 148 dispatch_reference(ref); 149 } 150 } while (!_refs->is_empty()); 151 } 152 153 HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state, 154 InCSetState* dest, 155 size_t word_sz, 156 bool previous_plab_refill_failed) { 157 assert(state.is_in_cset_or_humongous(), "Unexpected state: " CSETSTATE_FORMAT, state.value()); 158 assert(dest->is_in_cset_or_humongous(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value()); 159 160 // Right now we only have two types of regions (young / old) so 161 // let's keep the logic here simple. We can generalize it when necessary. 162 if (dest->is_young()) { 163 bool plab_refill_in_old_failed = false; 164 HeapWord* const obj_ptr = _plab_allocator->allocate(InCSetState::Old, 165 word_sz, 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) const { 206 PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_state); 207 if (alloc_buf->contains(obj_ptr)) { 208 _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz, age, 209 dest_state.value() == InCSetState::Old, 210 alloc_buf->word_sz()); 211 } else { 212 _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz, age, 213 dest_state.value() == InCSetState::Old); 214 } 215 } 216 217 oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state, 218 oop const old, 219 markOop const old_mark) { 220 const size_t word_sz = old->size(); 221 HeapRegion* const from_region = _g1h->heap_region_containing(old); 222 // +1 to make the -1 indexes valid... 223 const int young_index = from_region->young_index_in_cset()+1; 224 assert( (from_region->is_young() && young_index > 0) || 225 (!from_region->is_young() && young_index == 0), "invariant" ); 226 227 uint age = 0; 228 InCSetState dest_state = next_state(state, old_mark, age); 229 // The second clause is to prevent premature evacuation failure in case there 230 // is still space in survivor, but old gen is full. 231 if (_old_gen_is_full && dest_state.is_old()) { 232 return handle_evacuation_failure_par(old, old_mark); 233 } 234 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_state, word_sz); 235 236 // PLAB allocations should succeed most of the time, so we'll 237 // normally check against NULL once and that's it. 238 if (obj_ptr == NULL) { 239 bool plab_refill_failed = false; 240 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(dest_state, word_sz, &plab_refill_failed); 241 if (obj_ptr == NULL) { 242 obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, plab_refill_failed); 243 if (obj_ptr == NULL) { 244 // This will either forward-to-self, or detect that someone else has 245 // installed a forwarding pointer. 246 return handle_evacuation_failure_par(old, old_mark); 247 } 248 } 249 if (_g1h->_gc_tracer_stw->should_report_promotion_events()) { 250 // The events are checked individually as part of the actual commit 251 report_promotion_event(dest_state, old, word_sz, age, obj_ptr); 252 } 253 } 254 255 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded"); 256 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap"); 257 258 #ifndef PRODUCT 259 // Should this evacuation fail? 260 if (_g1h->evacuation_should_fail()) { 261 // Doing this after all the allocation attempts also tests the 262 // undo_allocation() method too. 263 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz); 264 return handle_evacuation_failure_par(old, old_mark); 265 } 266 #endif // !PRODUCT 267 268 // We're going to allocate linearly, so might as well prefetch ahead. 269 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 270 271 const oop obj = oop(obj_ptr); 272 const oop forward_ptr = old->forward_to_atomic(obj); 273 if (forward_ptr == NULL) { 274 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); 275 276 if (dest_state.is_young()) { 277 if (age < markOopDesc::max_age) { 278 age++; 279 } 280 if (old_mark->has_displaced_mark_helper()) { 281 // In this case, we have to install the mark word first, 282 // otherwise obj looks to be forwarded (the old mark word, 283 // which contains the forward pointer, was copied) 284 obj->set_mark(old_mark); 285 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age); 286 old_mark->set_displaced_mark_helper(new_mark); 287 } else { 288 obj->set_mark(old_mark->set_age(age)); 289 } 290 _age_table.add(age, word_sz); 291 } else { 292 obj->set_mark(old_mark); 293 } 294 295 if (G1StringDedup::is_enabled()) { 296 const bool is_from_young = state.is_young(); 297 const bool is_to_young = dest_state.is_young(); 298 assert(is_from_young == _g1h->heap_region_containing(old)->is_young(), 299 "sanity"); 300 assert(is_to_young == _g1h->heap_region_containing(obj)->is_young(), 301 "sanity"); 302 G1StringDedup::enqueue_from_evacuation(is_from_young, 303 is_to_young, 304 _worker_id, 305 obj); 306 } 307 308 _surviving_young_words[young_index] += word_sz; 309 310 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 311 // We keep track of the next start index in the length field of 312 // the to-space object. The actual length can be found in the 313 // length field of the from-space object. 314 arrayOop(obj)->set_length(0); 315 oop* old_p = set_partial_array_mask(old); 316 push_on_queue(old_p); 317 } else { 318 HeapRegion* const to_region = _g1h->heap_region_containing(obj_ptr); 319 _scanner.set_region(to_region); 320 obj->oop_iterate_backwards(&_scanner); 321 } 322 return obj; 323 } else { 324 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz); 325 return forward_ptr; 326 } 327 } 328 329 G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) { 330 assert(worker_id < _n_workers, "out of bounds access"); 331 if (_states[worker_id] == NULL) { 332 _states[worker_id] = new G1ParScanThreadState(_g1h, worker_id, _young_cset_length); 333 } 334 return _states[worker_id]; 335 } 336 337 const size_t* G1ParScanThreadStateSet::surviving_young_words() const { 338 assert(_flushed, "thread local state from the per thread states should have been flushed"); 339 return _surviving_young_words_total; 340 } 341 342 void G1ParScanThreadStateSet::flush() { 343 assert(!_flushed, "thread local state from the per thread states should be flushed once"); 344 345 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) { 346 G1ParScanThreadState* pss = _states[worker_index]; 347 348 if (pss == NULL) { 349 continue; 350 } 351 352 pss->flush(_surviving_young_words_total); 353 delete pss; 354 _states[worker_index] = NULL; 355 } 356 _flushed = true; 357 } 358 359 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop m) { 360 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old)); 361 362 oop forward_ptr = old->forward_to_atomic(old); 363 if (forward_ptr == NULL) { 364 // Forward-to-self succeeded. We are the "owner" of the object. 365 HeapRegion* r = _g1h->heap_region_containing(old); 366 367 if (!r->evacuation_failed()) { 368 r->set_evacuation_failed(true); 369 _g1h->hr_printer()->evac_failure(r); 370 } 371 372 _g1h->preserve_mark_during_evac_failure(_worker_id, old, m); 373 374 _scanner.set_region(r); 375 old->oop_iterate_backwards(&_scanner); 376 377 return old; 378 } else { 379 // Forward-to-self failed. Either someone else managed to allocate 380 // space for this object (old != forward_ptr) or they beat us in 381 // self-forwarding it (old == forward_ptr). 382 assert(old == forward_ptr || !_g1h->is_in_cset(forward_ptr), 383 "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " " 384 "should not be in the CSet", 385 p2i(old), p2i(forward_ptr)); 386 return forward_ptr; 387 } 388 } 389 G1ParScanThreadStateSet::G1ParScanThreadStateSet(G1CollectedHeap* g1h, uint n_workers, size_t young_cset_length) : 390 _g1h(g1h), 391 _states(NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC)), 392 _surviving_young_words_total(NEW_C_HEAP_ARRAY(size_t, young_cset_length, mtGC)), 393 _young_cset_length(young_cset_length), 394 _n_workers(n_workers), 395 _flushed(false) { 396 for (uint i = 0; i < n_workers; ++i) { 397 _states[i] = NULL; 398 } 399 memset(_surviving_young_words_total, 0, young_cset_length * sizeof(size_t)); 400 } 401 402 G1ParScanThreadStateSet::~G1ParScanThreadStateSet() { 403 assert(_flushed, "thread local state from the per thread states should have been flushed"); 404 FREE_C_HEAP_ARRAY(G1ParScanThreadState*, _states); 405 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_total); 406 }