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 _scanner.set_par_scan_thread_state(this); 46 // we allocate G1YoungSurvRateNumRegions plus one entries, since 47 // we "sacrifice" entry 0 to keep track of surviving bytes for 48 // non-young regions (where the age is -1) 49 // We also add a few elements at the beginning and at the end in 50 // an attempt to eliminate cache contention 51 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length(); 52 uint array_length = PADDING_ELEM_NUM + 53 real_length + 54 PADDING_ELEM_NUM; 55 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC); 56 if (_surviving_young_words_base == NULL) 57 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR, 58 "Not enough space for young surv histo."); 59 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM; 60 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t)); 61 62 _g1_par_allocator = G1ParGCAllocator::create_allocator(_g1h); 63 64 _dest[InCSetState::NotInCSet] = InCSetState::NotInCSet; 65 // The dest for Young is used when the objects are aged enough to 66 // need to be moved to the next space. 67 _dest[InCSetState::Young] = InCSetState::Old; 68 _dest[InCSetState::Old] = InCSetState::Old; 69 70 _start = os::elapsedTime(); 71 } 72 73 G1ParScanThreadState::~G1ParScanThreadState() { 74 _g1_par_allocator->retire_alloc_buffers(); 75 delete _g1_par_allocator; 76 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base); 77 } 78 79 void 80 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st) 81 { 82 st->print_raw_cr("GC Termination Stats"); 83 st->print_raw_cr(" elapsed --strong roots-- -------termination-------" 84 " ------waste (KiB)------"); 85 st->print_raw_cr("thr ms ms % ms % attempts" 86 " total alloc undo"); 87 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------" 88 " ------- ------- -------"); 89 } 90 91 void 92 G1ParScanThreadState::print_termination_stats(int i, 93 outputStream* const st) const 94 { 95 const double elapsed_ms = elapsed_time() * 1000.0; 96 const double s_roots_ms = strong_roots_time() * 1000.0; 97 const double term_ms = term_time() * 1000.0; 98 size_t alloc_buffer_waste = 0; 99 size_t undo_waste = 0; 100 _g1_par_allocator->waste(alloc_buffer_waste, undo_waste); 101 st->print_cr("%3d %9.2f %9.2f %6.2f " 102 "%9.2f %6.2f " SIZE_FORMAT_W(8) " " 103 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7), 104 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms, 105 term_ms, term_ms * 100 / elapsed_ms, term_attempts(), 106 (alloc_buffer_waste + undo_waste) * HeapWordSize / K, 107 alloc_buffer_waste * HeapWordSize / K, 108 undo_waste * HeapWordSize / K); 109 } 110 111 #ifdef ASSERT 112 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const { 113 assert(ref != NULL, "invariant"); 114 assert(UseCompressedOops, "sanity"); 115 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, p2i(ref))); 116 oop p = oopDesc::load_decode_heap_oop(ref); 117 assert(_g1h->is_in_g1_reserved(p), 118 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p))); 119 return true; 120 } 121 122 bool G1ParScanThreadState::verify_ref(oop* ref) const { 123 assert(ref != NULL, "invariant"); 124 if (has_partial_array_mask(ref)) { 125 // Must be in the collection set--it's already been copied. 126 oop p = clear_partial_array_mask(ref); 127 assert(_g1h->obj_in_cs(p), 128 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p))); 129 } else { 130 oop p = oopDesc::load_decode_heap_oop(ref); 131 assert(_g1h->is_in_g1_reserved(p), 132 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p))); 133 } 134 return true; 135 } 136 137 bool G1ParScanThreadState::verify_task(StarTask ref) const { 138 if (ref.is_narrow()) { 139 return verify_ref((narrowOop*) ref); 140 } else { 141 return verify_ref((oop*) ref); 142 } 143 } 144 #endif // ASSERT 145 146 void G1ParScanThreadState::trim_queue() { 147 assert(_evac_failure_cl != NULL, "not set"); 148 149 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 assert(state.is_in_cset_or_humongous(), err_msg("Unexpected state: " CSETSTATE_FORMAT, state.value())); 167 assert(dest->is_in_cset_or_humongous(), err_msg("Unexpected dest: " CSETSTATE_FORMAT, dest->value())); 168 169 // Right now we only have two types of regions (young / old) so 170 // let's keep the logic here simple. We can generalize it when necessary. 171 if (dest->is_young()) { 172 HeapWord* const obj_ptr = _g1_par_allocator->allocate(InCSetState::Old, 173 word_sz, context); 174 if (obj_ptr == NULL) { 175 return NULL; 176 } 177 // Make sure that we won't attempt to copy any other objects out 178 // of a survivor region (given that apparently we cannot allocate 179 // any new ones) to avoid coming into this slow path. 180 _tenuring_threshold = 0; 181 dest->set_old(); 182 return obj_ptr; 183 } else { 184 assert(dest->is_old(), err_msg("Unexpected dest: " CSETSTATE_FORMAT, dest->value())); 185 // no other space to try. 186 return NULL; 187 } 188 } 189 190 InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) { 191 if (state.is_young()) { 192 age = !m->has_displaced_mark_helper() ? m->age() 193 : m->displaced_mark_helper()->age(); 194 if (age < _tenuring_threshold) { 195 return state; 196 } 197 } 198 return dest(state); 199 } 200 201 oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state, 202 oop const old, 203 markOop const old_mark) { 204 const size_t word_sz = old->size(); 205 HeapRegion* const from_region = _g1h->heap_region_containing_raw(old); 206 // +1 to make the -1 indexes valid... 207 const int young_index = from_region->young_index_in_cset()+1; 208 assert( (from_region->is_young() && young_index > 0) || 209 (!from_region->is_young() && young_index == 0), "invariant" ); 210 const AllocationContext_t context = from_region->allocation_context(); 211 212 uint age = 0; 213 InCSetState dest_state = next_state(state, old_mark, age); 214 HeapWord* obj_ptr = _g1_par_allocator->plab_allocate(dest_state, word_sz, context); 215 216 // PLAB allocations should succeed most of the time, so we'll 217 // normally check against NULL once and that's it. 218 if (obj_ptr == NULL) { 219 obj_ptr = _g1_par_allocator->allocate_direct_or_new_plab(dest_state, word_sz, context); 220 if (obj_ptr == NULL) { 221 obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, context); 222 if (obj_ptr == NULL) { 223 // This will either forward-to-self, or detect that someone else has 224 // installed a forwarding pointer. 225 return _g1h->handle_evacuation_failure_par(this, old); 226 } 227 } 228 } 229 230 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded"); 231 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap"); 232 233 #ifndef PRODUCT 234 // Should this evacuation fail? 235 if (_g1h->evacuation_should_fail()) { 236 // Doing this after all the allocation attempts also tests the 237 // undo_allocation() method too. 238 _g1_par_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context); 239 return _g1h->handle_evacuation_failure_par(this, old); 240 } 241 #endif // !PRODUCT 242 243 // We're going to allocate linearly, so might as well prefetch ahead. 244 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes); 245 246 const oop obj = oop(obj_ptr); 247 const oop forward_ptr = old->forward_to_atomic(obj); 248 if (forward_ptr == NULL) { 249 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz); 250 251 if (dest_state.is_young()) { 252 if (age < markOopDesc::max_age) { 253 age++; 254 } 255 if (old_mark->has_displaced_mark_helper()) { 256 // In this case, we have to install the mark word first, 257 // otherwise obj looks to be forwarded (the old mark word, 258 // which contains the forward pointer, was copied) 259 obj->set_mark(old_mark); 260 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age); 261 old_mark->set_displaced_mark_helper(new_mark); 262 } else { 263 obj->set_mark(old_mark->set_age(age)); 264 } 265 age_table()->add(age, word_sz); 266 } else { 267 obj->set_mark(old_mark); 268 } 269 270 if (G1StringDedup::is_enabled()) { 271 const bool is_from_young = state.is_young(); 272 const bool is_to_young = dest_state.is_young(); 273 assert(is_from_young == _g1h->heap_region_containing_raw(old)->is_young(), 274 "sanity"); 275 assert(is_to_young == _g1h->heap_region_containing_raw(obj)->is_young(), 276 "sanity"); 277 G1StringDedup::enqueue_from_evacuation(is_from_young, 278 is_to_young, 279 queue_num(), 280 obj); 281 } 282 283 size_t* const surv_young_words = surviving_young_words(); 284 surv_young_words[young_index] += word_sz; 285 286 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) { 287 // We keep track of the next start index in the length field of 288 // the to-space object. The actual length can be found in the 289 // length field of the from-space object. 290 arrayOop(obj)->set_length(0); 291 oop* old_p = set_partial_array_mask(old); 292 push_on_queue(old_p); 293 } else { 294 HeapRegion* const to_region = _g1h->heap_region_containing_raw(obj_ptr); 295 _scanner.set_region(to_region); 296 obj->oop_iterate_backwards(&_scanner); 297 } 298 return obj; 299 } else { 300 _g1_par_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context); 301 return forward_ptr; 302 } 303 }