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_implementation/g1/g1CollectedHeap.inline.hpp"
27 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
28 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
29 #include "oops/oop.inline.hpp"
30 #include "runtime/prefetch.inline.hpp"
31
32 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)
33 : _g1h(g1h),
34 _refs(g1h->task_queue(queue_num)),
35 _dcq(&g1h->dirty_card_queue_set()),
36 _ct_bs(g1h->g1_barrier_set()),
37 _g1_rem(g1h->g1_rem_set()),
38 _hash_seed(17), _queue_num(queue_num),
39 _term_attempts(0),
40 _tenuring_threshold(g1h->g1_policy()->tenuring_threshold()),
41 _age_table(false), _scanner(g1h, rp),
42 _strong_roots_time(0), _term_time(0) {
43 _scanner.set_par_scan_thread_state(this);
44 // we allocate G1YoungSurvRateNumRegions plus one entries, since
45 // we "sacrifice" entry 0 to keep track of surviving bytes for
46 // non-young regions (where the age is -1)
47 // We also add a few elements at the beginning and at the end in
48 // an attempt to eliminate cache contention
49 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
50 uint array_length = PADDING_ELEM_NUM +
51 real_length +
52 PADDING_ELEM_NUM;
53 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
54 if (_surviving_young_words_base == NULL)
55 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
56 "Not enough space for young surv histo.");
57 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
58 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
59
60 _g1_par_allocator = G1ParGCAllocator::create_allocator(_g1h);
61
62 _dest[InCSetState::NotInCSet] = InCSetState::NotInCSet;
63 // The dest for Young is used when the objects are aged enough to
64 // need to be moved to the next space.
65 _dest[InCSetState::Young] = InCSetState::Old;
66 _dest[InCSetState::Old] = InCSetState::Old;
67
68 _start = os::elapsedTime();
69 }
70
71 G1ParScanThreadState::~G1ParScanThreadState() {
72 _g1_par_allocator->retire_alloc_buffers();
73 delete _g1_par_allocator;
74 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
75 }
76
77 void
78 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
79 {
80 st->print_raw_cr("GC Termination Stats");
81 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
82 " ------waste (KiB)------");
83 st->print_raw_cr("thr ms ms % ms % attempts"
84 " total alloc undo");
85 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
86 " ------- ------- -------");
87 }
88
89 void
90 G1ParScanThreadState::print_termination_stats(int i,
91 outputStream* const st) const
92 {
93 const double elapsed_ms = elapsed_time() * 1000.0;
94 const double s_roots_ms = strong_roots_time() * 1000.0;
95 const double term_ms = term_time() * 1000.0;
96 const size_t alloc_buffer_waste = _g1_par_allocator->alloc_buffer_waste();
97 const size_t undo_waste = _g1_par_allocator->undo_waste();
98 st->print_cr("%3d %9.2f %9.2f %6.2f "
99 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
100 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
101 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
102 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
103 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
104 alloc_buffer_waste * HeapWordSize / K,
105 undo_waste * HeapWordSize / K);
106 }
107
108 #ifdef ASSERT
109 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
110 assert(ref != NULL, "invariant");
111 assert(UseCompressedOops, "sanity");
112 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, p2i(ref)));
113 oop p = oopDesc::load_decode_heap_oop(ref);
114 assert(_g1h->is_in_g1_reserved(p),
115 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)));
116 return true;
117 }
118
119 bool G1ParScanThreadState::verify_ref(oop* ref) const {
120 assert(ref != NULL, "invariant");
121 if (has_partial_array_mask(ref)) {
122 // Must be in the collection set--it's already been copied.
123 oop p = clear_partial_array_mask(ref);
124 assert(_g1h->obj_in_cs(p),
125 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)));
126 } else {
127 oop p = oopDesc::load_decode_heap_oop(ref);
128 assert(_g1h->is_in_g1_reserved(p),
129 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p)));
130 }
131 return true;
132 }
133
134 bool G1ParScanThreadState::verify_task(StarTask ref) const {
135 if (ref.is_narrow()) {
136 return verify_ref((narrowOop*) ref);
137 } else {
138 return verify_ref((oop*) ref);
139 }
140 }
141 #endif // ASSERT
142
143 void G1ParScanThreadState::trim_queue() {
144 assert(_evac_failure_cl != NULL, "not set");
145
146 StarTask ref;
147 do {
148 // Drain the overflow stack first, so other threads can steal.
149 while (_refs->pop_overflow(ref)) {
150 dispatch_reference(ref);
151 }
152
153 while (_refs->pop_local(ref)) {
154 dispatch_reference(ref);
155 }
156 } while (!_refs->is_empty());
157 }
158
159 HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state,
160 InCSetState* dest,
161 size_t word_sz,
162 AllocationContext_t const context) {
163 assert(state.is_in_cset_or_humongous(), err_msg("Unexpected state: " CSETSTATE_FORMAT, state.value()));
164 assert(dest->is_in_cset_or_humongous(), err_msg("Unexpected dest: " CSETSTATE_FORMAT, dest->value()));
165
166 // Right now we only have two types of regions (young / old) so
167 // let's keep the logic here simple. We can generalize it when necessary.
168 if (dest->is_young()) {
169 HeapWord* const obj_ptr = _g1_par_allocator->allocate(InCSetState::Old,
170 word_sz, context);
171 if (obj_ptr == NULL) {
172 return NULL;
173 }
174 // Make sure that we won't attempt to copy any other objects out
175 // of a survivor region (given that apparently we cannot allocate
176 // any new ones) to avoid coming into this slow path.
177 _tenuring_threshold = 0;
178 dest->set_old();
179 return obj_ptr;
180 } else {
181 assert(dest->is_old(), err_msg("Unexpected dest: " CSETSTATE_FORMAT, dest->value()));
182 // no other space to try.
183 return NULL;
184 }
185 }
186
187 InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) {
188 if (state.is_young()) {
189 age = !m->has_displaced_mark_helper() ? m->age()
190 : m->displaced_mark_helper()->age();
191 if (age < _tenuring_threshold) {
192 return state;
193 }
194 }
195 return dest(state);
196 }
197
198 oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state,
199 oop const old,
200 markOop const old_mark) {
201 const size_t word_sz = old->size();
202 HeapRegion* const from_region = _g1h->heap_region_containing_raw(old);
203 // +1 to make the -1 indexes valid...
204 const int young_index = from_region->young_index_in_cset()+1;
205 assert( (from_region->is_young() && young_index > 0) ||
206 (!from_region->is_young() && young_index == 0), "invariant" );
207 const AllocationContext_t context = from_region->allocation_context();
208
209 uint age = 0;
210 InCSetState dest_state = next_state(state, old_mark, age);
211 HeapWord* obj_ptr = _g1_par_allocator->plab_allocate(dest_state, word_sz, context);
212
213 // PLAB allocations should succeed most of the time, so we'll
214 // normally check against NULL once and that's it.
215 if (obj_ptr == NULL) {
216 obj_ptr = _g1_par_allocator->allocate_direct_or_new_plab(dest_state, word_sz, context);
217 if (obj_ptr == NULL) {
218 obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, context);
219 if (obj_ptr == NULL) {
220 // This will either forward-to-self, or detect that someone else has
221 // installed a forwarding pointer.
222 return _g1h->handle_evacuation_failure_par(this, old);
223 }
224 }
225 }
226
227 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded");
228 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap");
229
230 #ifndef PRODUCT
231 // Should this evacuation fail?
232 if (_g1h->evacuation_should_fail()) {
233 // Doing this after all the allocation attempts also tests the
234 // undo_allocation() method too.
235 _g1_par_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context);
236 return _g1h->handle_evacuation_failure_par(this, old);
237 }
238 #endif // !PRODUCT
239
240 // We're going to allocate linearly, so might as well prefetch ahead.
241 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
242
243 const oop obj = oop(obj_ptr);
244 const oop forward_ptr = old->forward_to_atomic(obj);
245 if (forward_ptr == NULL) {
246 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
247
248 if (dest_state.is_young()) {
249 if (age < markOopDesc::max_age) {
250 age++;
251 }
252 if (old_mark->has_displaced_mark_helper()) {
253 // In this case, we have to install the mark word first,
254 // otherwise obj looks to be forwarded (the old mark word,
255 // which contains the forward pointer, was copied)
256 obj->set_mark(old_mark);
257 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age);
258 old_mark->set_displaced_mark_helper(new_mark);
259 } else {
260 obj->set_mark(old_mark->set_age(age));
261 }
262 age_table()->add(age, word_sz);
263 } else {
264 obj->set_mark(old_mark);
265 }
266
267 if (G1StringDedup::is_enabled()) {
268 const bool is_from_young = state.is_young();
269 const bool is_to_young = dest_state.is_young();
270 assert(is_from_young == _g1h->heap_region_containing_raw(old)->is_young(),
271 "sanity");
272 assert(is_to_young == _g1h->heap_region_containing_raw(obj)->is_young(),
273 "sanity");
274 G1StringDedup::enqueue_from_evacuation(is_from_young,
275 is_to_young,
276 queue_num(),
277 obj);
278 }
279
280 size_t* const surv_young_words = surviving_young_words();
281 surv_young_words[young_index] += word_sz;
282
283 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
284 // We keep track of the next start index in the length field of
285 // the to-space object. The actual length can be found in the
286 // length field of the from-space object.
287 arrayOop(obj)->set_length(0);
288 oop* old_p = set_partial_array_mask(old);
289 push_on_queue(old_p);
290 } else {
291 HeapRegion* const to_region = _g1h->heap_region_containing_raw(obj_ptr);
292 _scanner.set_region(to_region);
293 obj->oop_iterate_backwards(&_scanner);
294 }
295 return obj;
296 } else {
297 _g1_par_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context);
298 return forward_ptr;
299 }
300 }