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 "oops/oop.pcgc.inline.hpp"
31 #include "runtime/prefetch.inline.hpp"
32
33 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)
34 : _g1h(g1h),
35 _refs(g1h->task_queue(queue_num)),
36 _dcq(&g1h->dirty_card_queue_set()),
37 _ct_bs(g1h->g1_barrier_set()),
38 _g1_rem(g1h->g1_rem_set()),
39 _hash_seed(17), _queue_num(queue_num),
40 _term_attempts(0),
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 _start = os::elapsedTime();
63 }
64
65 G1ParScanThreadState::~G1ParScanThreadState() {
66 _g1_par_allocator->retire_alloc_buffers();
67 delete _g1_par_allocator;
68 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);
69 }
70
71 void
72 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
73 {
74 st->print_raw_cr("GC Termination Stats");
75 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
76 " ------waste (KiB)------");
77 st->print_raw_cr("thr ms ms % ms % attempts"
78 " total alloc undo");
79 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
80 " ------- ------- -------");
81 }
133 }
134 }
135 #endif // ASSERT
136
137 void G1ParScanThreadState::trim_queue() {
138 assert(_evac_failure_cl != NULL, "not set");
139
140 StarTask ref;
141 do {
142 // Drain the overflow stack first, so other threads can steal.
143 while (_refs->pop_overflow(ref)) {
144 dispatch_reference(ref);
145 }
146
147 while (_refs->pop_local(ref)) {
148 dispatch_reference(ref);
149 }
150 } while (!_refs->is_empty());
151 }
152
153 oop G1ParScanThreadState::copy_to_survivor_space(oop const old,
154 markOop const old_mark) {
155 size_t word_sz = old->size();
156 HeapRegion* from_region = _g1h->heap_region_containing_raw(old);
157 // +1 to make the -1 indexes valid...
158 int young_index = from_region->young_index_in_cset()+1;
159 assert( (from_region->is_young() && young_index > 0) ||
160 (!from_region->is_young() && young_index == 0), "invariant" );
161 G1CollectorPolicy* g1p = _g1h->g1_policy();
162 uint age = old_mark->has_displaced_mark_helper() ? old_mark->displaced_mark_helper()->age()
163 : old_mark->age();
164 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
165 word_sz);
166 AllocationContext_t context = from_region->allocation_context();
167 HeapWord* obj_ptr = _g1_par_allocator->allocate(alloc_purpose, word_sz, context);
168 #ifndef PRODUCT
169 // Should this evacuation fail?
170 if (_g1h->evacuation_should_fail()) {
171 if (obj_ptr != NULL) {
172 _g1_par_allocator->undo_allocation(alloc_purpose, obj_ptr, word_sz, context);
173 obj_ptr = NULL;
174 }
175 }
176 #endif // !PRODUCT
177
178 if (obj_ptr == NULL) {
179 // This will either forward-to-self, or detect that someone else has
180 // installed a forwarding pointer.
181 return _g1h->handle_evacuation_failure_par(this, old);
182 }
183
184 oop obj = oop(obj_ptr);
185
186 // We're going to allocate linearly, so might as well prefetch ahead.
187 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
188
189 oop forward_ptr = old->forward_to_atomic(obj);
190 if (forward_ptr == NULL) {
191 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
192
193 // alloc_purpose is just a hint to allocate() above, recheck the type of region
194 // we actually allocated from and update alloc_purpose accordingly
195 HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr);
196 alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured;
197
198 if (g1p->track_object_age(alloc_purpose)) {
199 if (age < markOopDesc::max_age) {
200 age++;
201 }
202 if (old_mark->has_displaced_mark_helper()) {
203 // In this case, we have to install the mark word first,
204 // otherwise obj looks to be forwarded (the old mark word,
205 // which contains the forward pointer, was copied)
206 obj->set_mark(old_mark);
207 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age);
208 old_mark->set_displaced_mark_helper(new_mark);
209 } else {
210 obj->set_mark(old_mark->set_age(age));
211 }
212 age_table()->add(age, word_sz);
213 } else {
214 obj->set_mark(old_mark);
215 }
216
217 if (G1StringDedup::is_enabled()) {
218 G1StringDedup::enqueue_from_evacuation(from_region->is_young(),
219 to_region->is_young(),
220 queue_num(),
221 obj);
222 }
223
224 size_t* surv_young_words = surviving_young_words();
225 surv_young_words[young_index] += word_sz;
226
227 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
228 // We keep track of the next start index in the length field of
229 // the to-space object. The actual length can be found in the
230 // length field of the from-space object.
231 arrayOop(obj)->set_length(0);
232 oop* old_p = set_partial_array_mask(old);
233 push_on_queue(old_p);
234 } else {
235 // No point in using the slower heap_region_containing() method,
236 // given that we know obj is in the heap.
237 _scanner.set_region(_g1h->heap_region_containing_raw(obj));
238 obj->oop_iterate_backwards(&_scanner);
239 }
240 } else {
241 _g1_par_allocator->undo_allocation(alloc_purpose, obj_ptr, word_sz, context);
242 obj = forward_ptr;
243 }
244 return obj;
245 }
|
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 "oops/oop.pcgc.inline.hpp"
31 #include "runtime/prefetch.inline.hpp"
32
33 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)
34 : _g1h(g1h),
35 _refs(g1h->task_queue(queue_num)),
36 _dcq(&g1h->dirty_card_queue_set()),
37 _ct_bs(g1h->g1_barrier_set()),
38 _g1_rem(g1h->g1_rem_set()),
39 _hash_seed(17), _queue_num(queue_num),
40 _term_attempts(0),
41 _tenuring_threshold(g1h->g1_policy()->tenuring_threshold()),
42 _age_table(false), _scanner(g1h, rp),
43 _strong_roots_time(0), _term_time(0) {
44 _scanner.set_par_scan_thread_state(this);
45 // we allocate G1YoungSurvRateNumRegions plus one entries, since
46 // we "sacrifice" entry 0 to keep track of surviving bytes for
47 // non-young regions (where the age is -1)
48 // We also add a few elements at the beginning and at the end in
49 // an attempt to eliminate cache contention
50 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
51 uint array_length = PADDING_ELEM_NUM +
52 real_length +
53 PADDING_ELEM_NUM;
54 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
55 if (_surviving_young_words_base == NULL)
56 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
57 "Not enough space for young surv histo.");
58 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
59 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
60
61 _g1_par_allocator = G1ParGCAllocator::create_allocator(_g1h);
62
63 _dest[InCSetState::NotInCSet] = InCSetState::NotInCSet;
64 // The dest for Young is used when the objects are aged enough to
65 // need to be moved to the next space.
66 _dest[InCSetState::Young] = InCSetState::Old;
67 _dest[InCSetState::Old] = InCSetState::Old;
68
69 _start = os::elapsedTime();
70 }
71
72 G1ParScanThreadState::~G1ParScanThreadState() {
73 _g1_par_allocator->retire_alloc_buffers();
74 delete _g1_par_allocator;
75 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);
76 }
77
78 void
79 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
80 {
81 st->print_raw_cr("GC Termination Stats");
82 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
83 " ------waste (KiB)------");
84 st->print_raw_cr("thr ms ms % ms % attempts"
85 " total alloc undo");
86 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
87 " ------- ------- -------");
88 }
140 }
141 }
142 #endif // ASSERT
143
144 void G1ParScanThreadState::trim_queue() {
145 assert(_evac_failure_cl != NULL, "not set");
146
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: %u", state.value()));
165 assert(dest->is_in_cset_or_humongous(), err_msg("Unexpected dest: %u", 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: %u", 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 _g1h->handle_evacuation_failure_par(this, old);
224 }
225 }
226 }
227
228 assert(obj_ptr != NULL, "when we get here, allocation should have succeeded");
229 #ifndef PRODUCT
230 // Should this evacuation fail?
231 if (_g1h->evacuation_should_fail()) {
232 // Doing this after all the allocation attempts also tests the
233 // undo_allocation() method too.
234 _g1_par_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context);
235 return _g1h->handle_evacuation_failure_par(this, old);
236 }
237 #endif // !PRODUCT
238
239 // We're going to allocate linearly, so might as well prefetch ahead.
240 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
241
242 const oop obj = oop(obj_ptr);
243 const oop forward_ptr = old->forward_to_atomic(obj);
244 if (forward_ptr == NULL) {
245 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
246
247 if (dest_state.is_young()) {
248 if (age < markOopDesc::max_age) {
249 age++;
250 }
251 if (old_mark->has_displaced_mark_helper()) {
252 // In this case, we have to install the mark word first,
253 // otherwise obj looks to be forwarded (the old mark word,
254 // which contains the forward pointer, was copied)
255 obj->set_mark(old_mark);
256 markOop new_mark = old_mark->displaced_mark_helper()->set_age(age);
257 old_mark->set_displaced_mark_helper(new_mark);
258 } else {
259 obj->set_mark(old_mark->set_age(age));
260 }
261 age_table()->add(age, word_sz);
262 } else {
263 obj->set_mark(old_mark);
264 }
265
266 if (G1StringDedup::is_enabled()) {
267 const bool is_from_young = state.is_young();
268 const bool is_to_young = dest_state.is_young();
269 assert(is_from_young == _g1h->heap_region_containing_raw(old)->is_young(),
270 "sanity");
271 assert(is_to_young == _g1h->heap_region_containing_raw(obj)->is_young(),
272 "sanity");
273 G1StringDedup::enqueue_from_evacuation(is_from_young,
274 is_to_young,
275 queue_num(),
276 obj);
277 }
278
279 size_t* const surv_young_words = surviving_young_words();
280 surv_young_words[young_index] += word_sz;
281
282 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
283 // We keep track of the next start index in the length field of
284 // the to-space object. The actual length can be found in the
285 // length field of the from-space object.
286 arrayOop(obj)->set_length(0);
287 oop* old_p = set_partial_array_mask(old);
288 push_on_queue(old_p);
289 } else {
290 HeapRegion* const to_region = _g1h->heap_region_containing_raw(obj_ptr);
291 _scanner.set_region(to_region);
292 obj->oop_iterate_backwards(&_scanner);
293 }
294 return obj;
295 } else {
296 _g1_par_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context);
297 return forward_ptr;
298 }
299 }
|