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/g1CollectedHeap.inline.hpp" 27 #include "gc/g1/g1OopClosures.inline.hpp" 28 #include "gc/g1/g1ParScanThreadState.inline.hpp" 29 #include "gc/g1/g1StringDedup.hpp" 30 #include "gc/shared/taskqueue.inline.hpp" 31 #include "oops/oop.inline.hpp" 32 #include "runtime/prefetch.inline.hpp" 33 34 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp) 35 : _g1h(g1h), 36 _refs(g1h->task_queue(queue_num)), 37 _dcq(&g1h->dirty_card_queue_set()), 38 _ct_bs(g1h->g1_barrier_set()), 39 _g1_rem(g1h->g1_rem_set()), 40 _hash_seed(17), _queue_num(queue_num), 41 _term_attempts(0), 42 _tenuring_threshold(g1h->g1_policy()->tenuring_threshold()), 43 _age_table(false), _scanner(g1h, rp), 44 _strong_roots_time(0), _term_time(0), 45 _no_more_space_in_old(false) 46 { 47 _scanner.set_par_scan_thread_state(this); 48 // we allocate G1YoungSurvRateNumRegions plus one entries, since 49 // we "sacrifice" entry 0 to keep track of surviving bytes for 50 // non-young regions (where the age is -1) 51 // We also add a few elements at the beginning and at the end in 52 // an attempt to eliminate cache contention 53 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length(); 54 uint array_length = PADDING_ELEM_NUM + 55 real_length + 56 PADDING_ELEM_NUM; 57 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); 58 if (_surviving_young_words_base == NULL) 59 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR, 60 "Not enough space for young surv histo."); 61 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 62 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t)); 63 64 _plab_allocator = G1PLABAllocator::create_allocator(_g1h->allocator()); 65 66 _dest[InCSetState::NotInCSet] = InCSetState::NotInCSet; 67 // The dest for Young is used when the objects are aged enough to 68 // need to be moved to the next space. 69 _dest[InCSetState::Young] = InCSetState::Old; 70 _dest[InCSetState::Old] = InCSetState::Old; 71 72 _start = os::elapsedTime(); 73 } 74 75 G1ParScanThreadState::~G1ParScanThreadState() { 76 _plab_allocator->retire_alloc_buffers(); 77 delete _plab_allocator; 78 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base); 79 } 80 81 void 82 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st) 83 { 84 st->print_raw_cr("GC Termination Stats"); 85 st->print_raw_cr(" elapsed --strong roots-- -------termination-------" 86 " ------waste (KiB)------"); 87 st->print_raw_cr("thr ms ms % ms % attempts" 88 " total alloc undo"); 89 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------" 90 " ------- ------- -------"); 91 } 92 93 void 94 G1ParScanThreadState::print_termination_stats(int i, 95 outputStream* const st) const 96 { 97 const double elapsed_ms = elapsed_time() * 1000.0; 98 const double s_roots_ms = strong_roots_time() * 1000.0; 99 const double term_ms = term_time() * 1000.0; 100 size_t alloc_buffer_waste = 0; 101 size_t undo_waste = 0; 102 _plab_allocator->waste(alloc_buffer_waste, undo_waste); 103 st->print_cr("%3d %9.2f %9.2f %6.2f " 104 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 105 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 106 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms, 107 term_ms, term_ms * 100 / elapsed_ms, term_attempts(), 108 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 109 alloc_buffer_waste * HeapWordSize / K, 110 undo_waste * HeapWordSize / K); 111 } 112 113 #ifdef ASSERT 114 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 115 assert(ref != NULL, "invariant"); 116 assert(UseCompressedOops, "sanity"); 117 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, p2i(ref))); 118 oop p = oopDesc::load_decode_heap_oop(ref); 119 assert(_g1h->is_in_g1_reserved(p), 120 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p))); 121 return true; 122 } 123 124 bool G1ParScanThreadState::verify_ref(oop* ref) const { 125 assert(ref != NULL, "invariant"); 126 if (has_partial_array_mask(ref)) { 127 // Must be in the collection set--it's already been copied. 128 oop p = clear_partial_array_mask(ref); 129 assert(_g1h->obj_in_cs(p), 130 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p))); 131 } else { 132 oop p = oopDesc::load_decode_heap_oop(ref); 133 assert(_g1h->is_in_g1_reserved(p), 134 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p))); 135 } 136 return true; 137 } 138 139 bool G1ParScanThreadState::verify_task(StarTask ref) const { 140 if (ref.is_narrow()) { 141 return verify_ref((narrowOop*) ref); 142 } else { 143 return verify_ref((oop*) ref); 144 } 145 } 146 #endif // ASSERT 147 148 void G1ParScanThreadState::trim_queue() { 149 StarTask ref; 150 do { 151 // Drain the overflow stack first, so other threads can steal. 152 while (_refs->pop_overflow(ref)) { 153 dispatch_reference(ref); 154 } 155 156 while (_refs->pop_local(ref)) { 157 dispatch_reference(ref); 158 } 159 } while (!_refs->is_empty()); 160 } 161 162 HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state, 163 InCSetState* dest, 164 size_t word_sz, 165 AllocationContext_t const context, 166 bool previous_plab_refill_failed) { 167 assert(state.is_in_cset_or_humongous(), err_msg("Unexpected state: " CSETSTATE_FORMAT, state.value())); 168 assert(dest->is_in_cset_or_humongous(), err_msg("Unexpected dest: " CSETSTATE_FORMAT, dest->value())); 169 170 // Right now we only have two types of regions (young / old) so 171 // let's keep the logic here simple. We can generalize it when necessary. 172 if (dest->is_young()) { 173 bool plab_refill_in_old_failed = false; 174 HeapWord* const obj_ptr = _plab_allocator->allocate(InCSetState::Old, 175 word_sz, 176 context, 177 &plab_refill_in_old_failed); 178 // Make sure that we won't attempt to copy any other objects out 179 // of a survivor region (given that apparently we cannot allocate 180 // any new ones) to avoid coming into this slow path again and again. 181 // Only consider failed PLAB refill here: failed inline allocations are 182 // typically large, so not indicative of remaining space. 183 if (previous_plab_refill_failed) { 184 _tenuring_threshold = 0; 185 } 186 187 if (obj_ptr != NULL) { 188 dest->set_old(); 189 } else { 190 // We just failed to allocate in old gen. The same idea as explained above 191 // for making survivor gen unavailable for allocation applies for old gen. 192 _no_more_space_in_old = plab_refill_in_old_failed; 193 } 194 return obj_ptr; 195 } else { 196 _no_more_space_in_old = previous_plab_refill_failed; 197 assert(dest->is_old(), err_msg("Unexpected dest: " CSETSTATE_FORMAT, dest->value())); 198 // no other space to try. 199 return NULL; 200 } 201 } 202 203 InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) { 204 if (state.is_young()) { 205 age = !m->has_displaced_mark_helper() ? m->age() 206 : m->displaced_mark_helper()->age(); 207 if (age < _tenuring_threshold) { 208 return state; 209 } 210 } 211 return dest(state); 212 } 213 214 oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state, 215 oop const old, 216 markOop const old_mark) { 217 const size_t word_sz = old->size(); 218 HeapRegion* const from_region = _g1h->heap_region_containing_raw(old); 219 // +1 to make the -1 indexes valid... 220 const int young_index = from_region->young_index_in_cset()+1; 221 assert( (from_region->is_young() && young_index > 0) || 222 (!from_region->is_young() && young_index == 0), "invariant" ); 223 const AllocationContext_t context = from_region->allocation_context(); 224 225 uint age = 0; 226 InCSetState dest_state = next_state(state, old_mark, age); 227 // The second clause is to prevent premature evacuation failure in case there 228 // is still space in survivor, but old gen is full. 229 if (_no_more_space_in_old && dest_state.is_old()) { 230 return handle_evacuation_failure_par(old, old_mark); 231 } 232 HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_state, word_sz, context); 233 234 // PLAB allocations should succeed most of the time, so we'll 235 // normally check against NULL once and that's it. 236 if (obj_ptr == NULL) { 237 bool plab_refill_failed = false; 238 obj_ptr = _plab_allocator->allocate_inline_or_new_plab(dest_state, word_sz, context, &plab_refill_failed); 239 if (obj_ptr == NULL) { 240 obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, context, plab_refill_failed); 241 if (obj_ptr == NULL) { 242 // This will either forward-to-self, or detect that someone else has 243 // installed a forwarding pointer. 244 return handle_evacuation_failure_par(old, old_mark); 245 } 246 } 247 } 248 249 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded"); 250 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap"); 251 252 #ifndef PRODUCT 253 // Should this evacuation fail? 254 if (_g1h->evacuation_should_fail()) { 255 // Doing this after all the allocation attempts also tests the 256 // undo_allocation() method too. 257 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context); 258 return handle_evacuation_failure_par(old, old_mark); 259 } 260 #endif // !PRODUCT 261 262 // We're going to allocate linearly, so might as well prefetch ahead. 263 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 264 265 const oop obj = oop(obj_ptr); 266 const oop forward_ptr = old->forward_to_atomic(obj); 267 if (forward_ptr == NULL) { 268 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); 269 270 if (dest_state.is_young()) { 271 if (age < markOopDesc::max_age) { 272 age++; 273 } 274 if (old_mark->has_displaced_mark_helper()) { 275 // In this case, we have to install the mark word first, 276 // otherwise obj looks to be forwarded (the old mark word, 277 // which contains the forward pointer, was copied) 278 obj->set_mark(old_mark); 279 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age); 280 old_mark->set_displaced_mark_helper(new_mark); 281 } else { 282 obj->set_mark(old_mark->set_age(age)); 283 } 284 age_table()->add(age, word_sz); 285 } else { 286 obj->set_mark(old_mark); 287 } 288 289 if (G1StringDedup::is_enabled()) { 290 const bool is_from_young = state.is_young(); 291 const bool is_to_young = dest_state.is_young(); 292 assert(is_from_young == _g1h->heap_region_containing_raw(old)->is_young(), 293 "sanity"); 294 assert(is_to_young == _g1h->heap_region_containing_raw(obj)->is_young(), 295 "sanity"); 296 G1StringDedup::enqueue_from_evacuation(is_from_young, 297 is_to_young, 298 queue_num(), 299 obj); 300 } 301 302 size_t* const surv_young_words = surviving_young_words(); 303 surv_young_words[young_index] += word_sz; 304 305 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 306 // We keep track of the next start index in the length field of 307 // the to-space object. The actual length can be found in the 308 // length field of the from-space object. 309 arrayOop(obj)->set_length(0); 310 oop* old_p = set_partial_array_mask(old); 311 push_on_queue(old_p); 312 } else { 313 HeapRegion* const to_region = _g1h->heap_region_containing_raw(obj_ptr); 314 _scanner.set_region(to_region); 315 obj->oop_iterate_backwards(&_scanner); 316 } 317 return obj; 318 } else { 319 _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context); 320 return forward_ptr; 321 } 322 } 323 324 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop m) { 325 assert(_g1h->obj_in_cs(old), 326 err_msg("Object " PTR_FORMAT " should be in the CSet", p2i(old))); 327 328 oop forward_ptr = old->forward_to_atomic(old); 329 if (forward_ptr == NULL) { 330 // Forward-to-self succeeded. We are the "owner" of the object. 331 HeapRegion* r = _g1h->heap_region_containing(old); 332 333 if (!r->evacuation_failed()) { 334 r->set_evacuation_failed(true); 335 _g1h->hr_printer()->evac_failure(r); 336 } 337 338 _g1h->preserve_mark_during_evac_failure(_queue_num, old, m); 339 340 _scanner.set_region(r); 341 old->oop_iterate_backwards(&_scanner); 342 343 return old; 344 } else { 345 // Forward-to-self failed. Either someone else managed to allocate 346 // space for this object (old != forward_ptr) or they beat us in 347 // self-forwarding it (old == forward_ptr). 348 assert(old == forward_ptr || !_g1h->obj_in_cs(forward_ptr), 349 err_msg("Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " " 350 "should not be in the CSet", 351 p2i(old), p2i(forward_ptr))); 352 return forward_ptr; 353 } 354 } 355