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/gcTrace.hpp" 34#include "gc/shared/taskqueue.inline.hpp" 35#include "oops/oop.inline.hpp" 36#include "runtime/prefetch.inline.hpp" 37 38G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint worker_id, size_t young_cset_length) 39 : _g1h(g1h), 40 _refs(g1h->task_queue(worker_id)), 41 _dcq(&g1h->dirty_card_queue_set()), 42 _ct_bs(g1h->g1_barrier_set()), 43 _closures(NULL), 44 _hash_seed(17), 45 _worker_id(worker_id), 46 _tenuring_threshold(g1h->g1_policy()->tenuring_threshold()), 47 _age_table(false), 48 _scanner(g1h, this), 49 _old_gen_is_full(false) 50{ 51 // we allocate G1YoungSurvRateNumRegions plus one entries, since 52 // we "sacrifice" entry 0 to keep track of surviving bytes for 53 // non-young regions (where the age is -1) 54 // We also add a few elements at the beginning and at the end in 55 // an attempt to eliminate cache contention 56 size_t real_length = 1 + young_cset_length; 57 size_t array_length = PADDING_ELEM_NUM + 58 real_length + 59 PADDING_ELEM_NUM; 60 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); 61 if (_surviving_young_words_base == NULL) 62 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR, 63 "Not enough space for young surv histo."); 64 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 65 memset(_surviving_young_words, 0, real_length * sizeof(size_t)); 66 67 _plab_allocator = G1PLABAllocator::create_allocator(_g1h->allocator()); 68 69 _dest[InCSetState::NotInCSet] = InCSetState::NotInCSet; 70 // The dest for Young is used when the objects are aged enough to 71 // need to be moved to the next space. 72 _dest[InCSetState::Young] = InCSetState::Old; 73 _dest[InCSetState::Old] = InCSetState::Old; 74 75 _closures = G1EvacuationRootClosures::create_root_closures(this, _g1h); 76} 77 78// Pass locally gathered statistics to global state. 79void G1ParScanThreadState::flush(size_t* surviving_young_words) { 80 _dcq.flush(); 81 // Update allocation statistics. 82 _plab_allocator->flush_and_retire_stats(); 83 _g1h->g1_policy()->record_age_table(&_age_table); 84 85 uint length = _g1h->collection_set()->young_region_length(); 86 for (uint region_index = 0; region_index < length; region_index++) { 87 surviving_young_words[region_index] += _surviving_young_words[region_index]; 88 } 89} 90 91G1ParScanThreadState::~G1ParScanThreadState() { 92 delete _plab_allocator; 93 delete _closures; 94 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base); 95} 96 97void G1ParScanThreadState::waste(size_t& wasted, size_t& undo_wasted) { 98 _plab_allocator->waste(wasted, undo_wasted); 99} 100 101#ifdef ASSERT 102bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 103 assert(ref != NULL, "invariant"); 104 assert(UseCompressedOops, "sanity"); 105 assert(!has_partial_array_mask(ref), "ref=" PTR_FORMAT, p2i(ref)); 106 oop p = oopDesc::load_decode_heap_oop(ref); 107 assert(_g1h->is_in_g1_reserved(p), 108 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 109 return true; 110} 111 112bool G1ParScanThreadState::verify_ref(oop* ref) const { 113 assert(ref != NULL, "invariant"); 114 if (has_partial_array_mask(ref)) { 115 // Must be in the collection set--it's already been copied. 116 oop p = clear_partial_array_mask(ref); 117 assert(_g1h->is_in_cset(p), 118 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 119 } else { 120 oop p = oopDesc::load_decode_heap_oop(ref); 121 assert(_g1h->is_in_g1_reserved(p), 122 "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)); 123 } 124 return true; 125} 126 127bool G1ParScanThreadState::verify_task(StarTask ref) const { 128 if (ref.is_narrow()) { 129 return verify_ref((narrowOop*) ref); 130 } else { 131 return verify_ref((oop*) ref); 132 } 133} 134#endif // ASSERT 135 136void G1ParScanThreadState::trim_queue() { 137 StarTask ref; 138 do { 139 // Drain the overflow stack first, so other threads can steal. 140 while (_refs->pop_overflow(ref)) { 141 if (!_refs->try_push_to_taskqueue(ref)) { 142 dispatch_reference(ref); 143 } 144 } 145 146 while (_refs->pop_local(ref)) { 147 dispatch_reference(ref); 148 } 149 } while (!_refs->is_empty()); 150} 151 152HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state, 153 InCSetState* dest, 154 size_t word_sz, 155 AllocationContext_t const context, 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 context, 167 &plab_refill_in_old_failed); 168 // Make sure that we won't attempt to copy any other objects out 169 // of a survivor region (given that apparently we cannot allocate 170 // any new ones) to avoid coming into this slow path again and again. 171 // Only consider failed PLAB refill here: failed inline allocations are 172 // typically large, so not indicative of remaining space. 173 if (previous_plab_refill_failed) { 174 _tenuring_threshold = 0; 175 } 176 177 if (obj_ptr != NULL) { 178 dest->set_old(); 179 } else { 180 // We just failed to allocate in old gen. The same idea as explained above 181 // for making survivor gen unavailable for allocation applies for old gen. 182 _old_gen_is_full = plab_refill_in_old_failed; 183 } 184 return obj_ptr; 185 } else { 186 _old_gen_is_full = previous_plab_refill_failed; 187 assert(dest->is_old(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value()); 188 // no other space to try. 189 return NULL; 190 } 191} 192 193InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) { 194 if (state.is_young()) { 195 age = !m->has_displaced_mark_helper() ? m->age() 196 : m->displaced_mark_helper()->age(); 197 if (age < _tenuring_threshold) { 198 return state; 199 } 200 } 201 return dest(state); 202} 203 204void G1ParScanThreadState::report_promotion_event(InCSetState const dest_state, 205 oop const old, size_t word_sz, uint age, 206 HeapWord * const obj_ptr, 207 const AllocationContext_t context) const { 208 G1PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_state, context); 209 if (alloc_buf->contains(obj_ptr)) { 210 _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz, age, 211 dest_state.value() == InCSetState::Old, 212 alloc_buf->word_sz()); 213 } else { 214 _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz, age, 215 dest_state.value() == InCSetState::Old); 216 } 217} 218 219oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state, 220 oop const old, 221 markOop const old_mark) { 222 const size_t word_sz = old->size(); 223 HeapRegion* const from_region = _g1h->heap_region_containing(old); 224 // +1 to make the -1 indexes valid... 225 const int young_index = from_region->young_index_in_cset()+1; 226 assert( (from_region->is_young() && young_index > 0) || 227 (!from_region->is_young() && young_index == 0), "invariant" ); 228 const AllocationContext_t context = from_region->allocation_context(); 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, context); 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, context, &plab_refill_failed); 244 if (obj_ptr == NULL) { 245 obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, context, 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, context); 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, context); 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); 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(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(old_mark->set_age(age)); 292 } 293 _age_table.add(age, word_sz); 294 } else { 295 obj->set_mark(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 push_on_queue(old_p); 320 } else { 321 HeapRegion* const to_region = _g1h->heap_region_containing(obj_ptr); 322 _scanner.set_region(to_region); 323 obj->oop_iterate_backwards(&_scanner); 324 } 325 return obj; 326 } else { 327 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context); 328 return forward_ptr; 329 } 330} 331 332G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) { 333 assert(worker_id < _n_workers, "out of bounds access"); 334 if (_states[worker_id] == NULL) { 335 _states[worker_id] = new_par_scan_state(worker_id, _young_cset_length); 336 } 337 return _states[worker_id]; 338} 339 340const 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 345void 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 362oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop m) { 363 assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old)); 364 365 oop forward_ptr = old->forward_to_atomic(old); 366 if (forward_ptr == NULL) { 367 // Forward-to-self succeeded. We are the "owner" of the object. 368 HeapRegion* r = _g1h->heap_region_containing(old); 369 370 if (!r->evacuation_failed()) { 371 r->set_evacuation_failed(true); 372 _g1h->hr_printer()->evac_failure(r); 373 } 374 375 _g1h->preserve_mark_during_evac_failure(_worker_id, old, m); 376 377 _scanner.set_region(r); 378 old->oop_iterate_backwards(&_scanner); 379 380 return old; 381 } else { 382 // Forward-to-self failed. Either someone else managed to allocate 383 // space for this object (old != forward_ptr) or they beat us in 384 // self-forwarding it (old == forward_ptr). 385 assert(old == forward_ptr || !_g1h->is_in_cset(forward_ptr), 386 "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " " 387 "should not be in the CSet", 388 p2i(old), p2i(forward_ptr)); 389 return forward_ptr; 390 } 391} 392 393