1 /* 2 * Copyright (c) 2014, 2015, 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/g1OopClosures.inline.hpp" 29 #include "gc/g1/g1ParScanThreadState.inline.hpp" 30 #include "gc/g1/g1RootClosures.hpp" 31 #include "gc/g1/g1StringDedup.hpp" 32 #include "gc/shared/taskqueue.inline.hpp" 33 #include "oops/oop.inline.hpp" 34 #include "runtime/prefetch.inline.hpp" 35 36 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint worker_id, size_t young_cset_length) 37 : _g1h(g1h), 38 _refs(g1h->task_queue(worker_id)), 39 _dcq(&g1h->dirty_card_queue_set()), 40 _ct_bs(g1h->g1_barrier_set()), 41 _closures(NULL), 42 _hash_seed(17), 43 _worker_id(worker_id), 44 _tenuring_threshold(g1h->g1_policy()->tenuring_threshold()), 45 _age_table(false), 46 _scanner(g1h, this), 47 _old_gen_is_full(false) 48 { 49 // we allocate G1YoungSurvRateNumRegions plus one entries, since 50 // we "sacrifice" entry 0 to keep track of surviving bytes for 51 // non-young regions (where the age is -1) 52 // We also add a few elements at the beginning and at the end in 53 // an attempt to eliminate cache contention 54 size_t real_length = 1 + young_cset_length; 55 size_t array_length = PADDING_ELEM_NUM + 56 real_length + 57 PADDING_ELEM_NUM; 58 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); 59 if (_surviving_young_words_base == NULL) 60 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR, 61 "Not enough space for young surv histo."); 62 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 63 memset(_surviving_young_words, 0, real_length * sizeof(size_t)); 64 65 _plab_allocator = G1PLABAllocator::create_allocator(_g1h->allocator()); 66 67 _dest[InCSetState::NotInCSet] = InCSetState::NotInCSet; 68 // The dest for Young is used when the objects are aged enough to 69 // need to be moved to the next space. 70 _dest[InCSetState::Young] = InCSetState::Old; 71 _dest[InCSetState::Old] = InCSetState::Old; 72 73 _closures = G1EvacuationRootClosures::create_root_closures(this, _g1h); 74 } 75 76 // Pass locally gathered statistics to global state. 77 void G1ParScanThreadState::flush(size_t* surviving_young_words) { 78 _dcq.flush(); 79 // Update allocation statistics. 80 _plab_allocator->flush_and_retire_stats(); 81 _g1h->g1_policy()->record_age_table(&_age_table); 82 83 uint length = _g1h->g1_policy()->young_cset_region_length(); 84 for (uint region_index = 0; region_index < length; region_index++) { 85 surviving_young_words[region_index] += _surviving_young_words[region_index]; 86 } 87 } 88 89 G1ParScanThreadState::~G1ParScanThreadState() { 90 delete _plab_allocator; 91 delete _closures; 92 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base); 93 } 94 95 void G1ParScanThreadState::waste(size_t& wasted, size_t& undo_wasted) { 96 _plab_allocator->waste(wasted, undo_wasted); 97 } 98 99 #ifdef ASSERT 100 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 101 assert(ref != NULL, "invariant"); 102 assert(UseCompressedOops, "sanity"); 103 assert(!has_partial_array_mask(ref), "ref=" PTR_FORMAT, p2i(ref)); 104 oop p = oopDesc::load_decode_heap_oop(ref); 105 assert(_g1h->is_in_g1_reserved(p), 106 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 107 return true; 108 } 109 110 bool G1ParScanThreadState::verify_ref(oop* ref) const { 111 assert(ref != NULL, "invariant"); 112 if (has_partial_array_mask(ref)) { 113 // Must be in the collection set--it's already been copied. 114 oop p = clear_partial_array_mask(ref); 115 assert(_g1h->obj_in_cs(p), 116 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 117 } else { 118 oop p = oopDesc::load_decode_heap_oop(ref); 119 assert(_g1h->is_in_g1_reserved(p), 120 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 121 } 122 return true; 123 } 124 125 bool G1ParScanThreadState::verify_task(StarTask ref) const { 126 if (ref.is_narrow()) { 127 return verify_ref((narrowOop*) ref); 128 } else { 129 return verify_ref((oop*) ref); 130 } 131 } 132 #endif // ASSERT 133 134 void G1ParScanThreadState::trim_queue() { 135 StarTask ref; 136 do { 137 // Drain the overflow stack first, so other threads can steal. 138 while (_refs->pop_overflow(ref)) { 139 dispatch_reference(ref); 140 } 141 142 while (_refs->pop_local(ref)) { 143 dispatch_reference(ref); 144 } 145 } while (!_refs->is_empty()); 146 } 147 148 HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state, 149 InCSetState* dest, 150 size_t word_sz, 151 AllocationContext_t const context, 152 bool previous_plab_refill_failed) { 153 assert(state.is_in_cset_or_humongous(), "Unexpected state: " CSETSTATE_FORMAT, state.value()); 154 assert(dest->is_in_cset_or_humongous(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value()); 155 156 // Right now we only have two types of regions (young / old) so 157 // let's keep the logic here simple. We can generalize it when necessary. 158 if (dest->is_young()) { 159 bool plab_refill_in_old_failed = false; 160 HeapWord* const obj_ptr = _plab_allocator->allocate(InCSetState::Old, 161 word_sz, 162 context, 163 &plab_refill_in_old_failed); 164 // Make sure that we won't attempt to copy any other objects out 165 // of a survivor region (given that apparently we cannot allocate 166 // any new ones) to avoid coming into this slow path again and again. 167 // Only consider failed PLAB refill here: failed inline allocations are 168 // typically large, so not indicative of remaining space. 169 if (previous_plab_refill_failed) { 170 _tenuring_threshold = 0; 171 } 172 173 if (obj_ptr != NULL) { 174 dest->set_old(); 175 } else { 176 // We just failed to allocate in old gen. The same idea as explained above 177 // for making survivor gen unavailable for allocation applies for old gen. 178 _old_gen_is_full = plab_refill_in_old_failed; 179 } 180 return obj_ptr; 181 } else { 182 _old_gen_is_full = previous_plab_refill_failed; 183 assert(dest->is_old(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value()); 184 // no other space to try. 185 return NULL; 186 } 187 } 188 189 InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) { 190 if (state.is_young()) { 191 age = !m->has_displaced_mark_helper() ? m->age() 192 : m->displaced_mark_helper()->age(); 193 if (age < _tenuring_threshold) { 194 return state; 195 } 196 } 197 return dest(state); 198 } 199 200 void G1ParScanThreadState::report_promotion_event(InCSetState const dest_state, 201 oop const old, size_t word_sz, uint age, 202 HeapWord * const obj_ptr, 203 const AllocationContext_t context) const { 204 G1PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_state, context); 205 if (alloc_buf->contains(obj_ptr)) { 206 _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz, age, 207 dest_state.value() == InCSetState::Old, 208 alloc_buf->word_sz()); 209 } else { 210 _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz, age, 211 dest_state.value() == InCSetState::Old); 212 } 213 } 214 215 oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state, 216 oop const old, 217 markOop const old_mark) { 218 const size_t word_sz = old->size(); 219 HeapRegion* const from_region = _g1h->heap_region_containing(old); 220 // +1 to make the -1 indexes valid... 221 const int young_index = from_region->young_index_in_cset()+1; 222 assert( (from_region->is_young() && young_index > 0) || 223 (!from_region->is_young() && young_index == 0), "invariant" ); 224 const AllocationContext_t context = from_region->allocation_context(); 225 226 uint age = 0; 227 InCSetState dest_state = next_state(state, old_mark, age); 228 // The second clause is to prevent premature evacuation failure in case there 229 // is still space in survivor, but old gen is full. 230 if (_old_gen_is_full && dest_state.is_old()) { 231 return handle_evacuation_failure_par(old, old_mark); 232 } 233 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_state, word_sz, context); 234 235 // PLAB allocations should succeed most of the time, so we'll 236 // normally check against NULL once and that's it. 237 if (obj_ptr == NULL) { 238 bool plab_refill_failed = false; 239 obj_ptr = _plab_allocator->allocate_direct_or_new_plab(dest_state, word_sz, context, &plab_refill_failed); 240 if (obj_ptr == NULL) { 241 obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, context, plab_refill_failed); 242 if (obj_ptr == NULL) { 243 // This will either forward-to-self, or detect that someone else has 244 // installed a forwarding pointer. 245 return handle_evacuation_failure_par(old, old_mark); 246 } 247 } 248 if (_g1h->_gc_tracer_stw->should_report_promotion_events()) { 249 // The events are checked individually as part of the actual commit 250 report_promotion_event(dest_state, old, word_sz, age, obj_ptr, context); 251 } 252 } 253 254 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded"); 255 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap"); 256 257 #ifndef PRODUCT 258 // Should this evacuation fail? 259 if (_g1h->evacuation_should_fail()) { 260 // Doing this after all the allocation attempts also tests the 261 // undo_allocation() method too. 262 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context); 263 return handle_evacuation_failure_par(old, old_mark); 264 } 265 #endif // !PRODUCT 266 267 // We're going to allocate linearly, so might as well prefetch ahead. 268 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 269 270 const oop obj = oop(obj_ptr); 271 const oop forward_ptr = old->forward_to_atomic(obj); 272 if (forward_ptr == NULL) { 273 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); 274 275 if (dest_state.is_young()) { 276 if (age < markOopDesc::max_age) { 277 age++; 278 } 279 if (old_mark->has_displaced_mark_helper()) { 280 // In this case, we have to install the mark word first, 281 // otherwise obj looks to be forwarded (the old mark word, 282 // which contains the forward pointer, was copied) 283 obj->set_mark(old_mark); 284 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age); 285 old_mark->set_displaced_mark_helper(new_mark); 286 } else { 287 obj->set_mark(old_mark->set_age(age)); 288 } 289 _age_table.add(age, word_sz); 290 } else { 291 obj->set_mark(old_mark); 292 } 293 294 if (G1StringDedup::is_enabled()) { 295 const bool is_from_young = state.is_young(); 296 const bool is_to_young = dest_state.is_young(); 297 assert(is_from_young == _g1h->heap_region_containing(old)->is_young(), 298 "sanity"); 299 assert(is_to_young == _g1h->heap_region_containing(obj)->is_young(), 300 "sanity"); 301 G1StringDedup::enqueue_from_evacuation(is_from_young, 302 is_to_young, 303 _worker_id, 304 obj); 305 } 306 307 _surviving_young_words[young_index] += word_sz; 308 309 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 310 // We keep track of the next start index in the length field of 311 // the to-space object. The actual length can be found in the 312 // length field of the from-space object. 313 arrayOop(obj)->set_length(0); 314 oop* old_p = set_partial_array_mask(old); 315 push_on_queue(old_p); 316 } else { 317 HeapRegion* const to_region = _g1h->heap_region_containing(obj_ptr); 318 _scanner.set_region(to_region); 319 obj->oop_iterate_backwards(&_scanner); 320 } 321 return obj; 322 } else { 323 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context); 324 return forward_ptr; 325 } 326 } 327 328 G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) { 329 assert(worker_id < _n_workers, "out of bounds access"); 330 return _states[worker_id]; 331 } 332 333 void G1ParScanThreadStateSet::add_cards_scanned(uint worker_id, size_t cards_scanned) { 334 assert(worker_id < _n_workers, "out of bounds access"); 335 _cards_scanned[worker_id] += cards_scanned; 336 } 337 338 size_t G1ParScanThreadStateSet::total_cards_scanned() const { 339 assert(_flushed, "thread local state from the per thread states should have been flushed"); 340 return _total_cards_scanned; 341 } 342 343 const size_t* G1ParScanThreadStateSet::surviving_young_words() const { 344 assert(_flushed, "thread local state from the per thread states should have been flushed"); 345 return _surviving_young_words_total; 346 } 347 348 void G1ParScanThreadStateSet::flush() { 349 assert(!_flushed, "thread local state from the per thread states should be flushed once"); 350 assert(_total_cards_scanned == 0, "should have been cleared"); 351 352 for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) { 353 G1ParScanThreadState* pss = _states[worker_index]; 354 355 _total_cards_scanned += _cards_scanned[worker_index]; 356 357 pss->flush(_surviving_young_words_total); 358 delete pss; 359 _states[worker_index] = NULL; 360 } 361 _flushed = true; 362 } 363 364 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop m) { 365 assert(_g1h->obj_in_cs(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old)); 366 367 oop forward_ptr = old->forward_to_atomic(old); 368 if (forward_ptr == NULL) { 369 // Forward-to-self succeeded. We are the "owner" of the object. 370 HeapRegion* r = _g1h->heap_region_containing(old); 371 372 if (!r->evacuation_failed()) { 373 r->set_evacuation_failed(true); 374 _g1h->hr_printer()->evac_failure(r); 375 } 376 377 _g1h->preserve_mark_during_evac_failure(_worker_id, old, m); 378 379 _scanner.set_region(r); 380 old->oop_iterate_backwards(&_scanner); 381 382 return old; 383 } else { 384 // Forward-to-self failed. Either someone else managed to allocate 385 // space for this object (old != forward_ptr) or they beat us in 386 // self-forwarding it (old == forward_ptr). 387 assert(old == forward_ptr || !_g1h->obj_in_cs(forward_ptr), 388 "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " " 389 "should not be in the CSet", 390 p2i(old), p2i(forward_ptr)); 391 return forward_ptr; 392 } 393 } 394