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 StarTask ref;
148 do {
149 // Drain the overflow stack first, so other threads can steal.
150 while (_refs->pop_overflow(ref)) {
151 dispatch_reference(ref);
152 }
153
154 while (_refs->pop_local(ref)) {
155 dispatch_reference(ref);
156 }
157 } while (!_refs->is_empty());
158 }
159
160 HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state,
161 InCSetState* dest,
162 size_t word_sz,
163 AllocationContext_t const context) {
164 assert(state.is_in_cset_or_humongous(), err_msg("Unexpected state: " CSETSTATE_FORMAT, state.value()));
165 assert(dest->is_in_cset_or_humongous(), err_msg("Unexpected dest: " CSETSTATE_FORMAT, dest->value()));
166
167 // Right now we only have two types of regions (young / old) so
168 // let's keep the logic here simple. We can generalize it when necessary.
169 if (dest->is_young()) {
170 HeapWord* const obj_ptr = _g1_par_allocator->allocate(InCSetState::Old,
171 word_sz, context);
172 if (obj_ptr == NULL) {
173 return NULL;
174 }
175 // Make sure that we won't attempt to copy any other objects out
176 // of a survivor region (given that apparently we cannot allocate
177 // any new ones) to avoid coming into this slow path.
178 _tenuring_threshold = 0;
179 dest->set_old();
180 return obj_ptr;
181 } else {
182 assert(dest->is_old(), err_msg("Unexpected dest: " CSETSTATE_FORMAT, dest->value()));
183 // no other space to try.
184 return NULL;
185 }
186 }
187
188 InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) {
189 if (state.is_young()) {
190 age = !m->has_displaced_mark_helper() ? m->age()
191 : m->displaced_mark_helper()->age();
192 if (age < _tenuring_threshold) {
193 return state;
194 }
195 }
196 return dest(state);
197 }
198
199 oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state,
200 oop const old,
201 markOop const old_mark) {
202 const size_t word_sz = old->size();
203 HeapRegion* const from_region = _g1h->heap_region_containing_raw(old);
204 // +1 to make the -1 indexes valid...
205 const int young_index = from_region->young_index_in_cset()+1;
206 assert( (from_region->is_young() && young_index > 0) ||
207 (!from_region->is_young() && young_index == 0), "invariant" );
208 const AllocationContext_t context = from_region->allocation_context();
209
210 uint age = 0;
211 InCSetState dest_state = next_state(state, old_mark, age);
212 HeapWord* obj_ptr = _g1_par_allocator->plab_allocate(dest_state, word_sz, context);
213
214 // PLAB allocations should succeed most of the time, so we'll
215 // normally check against NULL once and that's it.
216 if (obj_ptr == NULL) {
217 obj_ptr = _g1_par_allocator->allocate_direct_or_new_plab(dest_state, word_sz, context);
218 if (obj_ptr == NULL) {
219 obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, context);
220 if (obj_ptr == NULL) {
221 // This will either forward-to-self, or detect that someone else has
222 // installed a forwarding pointer.
223 return handle_evacuation_failure_par(old, old_mark);
224 }
225 }
226 }
227
228 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded");
229 assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap");
230
231 #ifndef PRODUCT
232 // Should this evacuation fail?
233 if (_g1h->evacuation_should_fail()) {
234 // Doing this after all the allocation attempts also tests the
235 // undo_allocation() method too.
236 _g1_par_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context);
237 return handle_evacuation_failure_par(old, old_mark);
238 }
239 #endif // !PRODUCT
240
241 // We're going to allocate linearly, so might as well prefetch ahead.
242 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
243
244 const oop obj = oop(obj_ptr);
245 const oop forward_ptr = old->forward_to_atomic(obj);
246 if (forward_ptr == NULL) {
247 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
248
249 if (dest_state.is_young()) {
250 if (age < markOopDesc::max_age) {
251 age++;
252 }
253 if (old_mark->has_displaced_mark_helper()) {
254 // In this case, we have to install the mark word first,
255 // otherwise obj looks to be forwarded (the old mark word,
256 // which contains the forward pointer, was copied)
257 obj->set_mark(old_mark);
258 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age);
259 old_mark->set_displaced_mark_helper(new_mark);
260 } else {
261 obj->set_mark(old_mark->set_age(age));
262 }
263 age_table()->add(age, word_sz);
264 } else {
265 obj->set_mark(old_mark);
266 }
267
268 if (G1StringDedup::is_enabled()) {
269 const bool is_from_young = state.is_young();
270 const bool is_to_young = dest_state.is_young();
271 assert(is_from_young == _g1h->heap_region_containing_raw(old)->is_young(),
272 "sanity");
273 assert(is_to_young == _g1h->heap_region_containing_raw(obj)->is_young(),
274 "sanity");
275 G1StringDedup::enqueue_from_evacuation(is_from_young,
276 is_to_young,
277 queue_num(),
278 obj);
279 }
280
281 size_t* const surv_young_words = surviving_young_words();
282 surv_young_words[young_index] += word_sz;
283
284 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
285 // We keep track of the next start index in the length field of
286 // the to-space object. The actual length can be found in the
287 // length field of the from-space object.
288 arrayOop(obj)->set_length(0);
289 oop* old_p = set_partial_array_mask(old);
290 push_on_queue(old_p);
291 } else {
292 HeapRegion* const to_region = _g1h->heap_region_containing_raw(obj_ptr);
293 _scanner.set_region(to_region);
294 obj->oop_iterate_backwards(&_scanner);
295 }
296 return obj;
297 } else {
298 _g1_par_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context);
299 return forward_ptr;
300 }
301 }
302
303 oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop m) {
304 assert(_g1h->obj_in_cs(old),
305 err_msg("Object " PTR_FORMAT " should be in the CSet", p2i(old)));
306
307 oop forward_ptr = old->forward_to_atomic(old);
308 if (forward_ptr == NULL) {
309 // Forward-to-self succeeded. We are the "owner" of the object.
310 HeapRegion* r = _g1h->heap_region_containing(old);
311
312 if (!r->evacuation_failed()) {
313 r->set_evacuation_failed(true);
314 _g1h->hr_printer()->evac_failure(r);
315 }
316
317 _g1h->preserve_mark_during_evac_failure(_queue_num, old, m);
318
319 _scanner.set_region(r);
320 old->oop_iterate_backwards(&_scanner);
321
322 return old;
323 } else {
324 // Forward-to-self failed. Either someone else managed to allocate
325 // space for this object (old != forward_ptr) or they beat us in
326 // self-forwarding it (old == forward_ptr).
327 assert(old == forward_ptr || !_g1h->obj_in_cs(forward_ptr),
328 err_msg("Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " "
329 "should not be in the CSet",
330 p2i(old), p2i(forward_ptr)));
331 return forward_ptr;
332 }
333 }