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.hpp"
27 #include "gc/g1/g1CollectionSet.hpp"
28 #include "gc/g1/g1CollectorState.hpp"
29 #include "gc/g1/g1Policy.hpp"
30 #include "gc/g1/heapRegion.inline.hpp"
31 #include "gc/g1/heapRegionRemSet.hpp"
32 #include "gc/g1/heapRegionSet.hpp"
33 #include "utilities/debug.hpp"
34
35 G1CollectorState* G1CollectionSet::collector_state() {
36 return _g1->collector_state();
37 }
38
39 G1GCPhaseTimes* G1CollectionSet::phase_times() {
40 return _policy->phase_times();
41 }
42
43 CollectionSetChooser* G1CollectionSet::cset_chooser() {
44 return _cset_chooser;
45 }
46
47 double G1CollectionSet::predict_region_elapsed_time_ms(HeapRegion* hr) {
48 return _policy->predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
49 }
50
51 G1CollectionSet::G1CollectionSet(G1CollectedHeap* g1h, G1Policy* policy) :
52 _g1(g1h),
53 _policy(policy),
54 _cset_chooser(new CollectionSetChooser()),
55 _eden_region_length(0),
56 _survivor_region_length(0),
57 _old_region_length(0),
58
59 _head(NULL),
60 _bytes_used_before(0),
61 _recorded_rs_lengths(0),
62 // Incremental CSet attributes
63 _inc_build_state(Inactive),
64 _inc_head(NULL),
65 _inc_tail(NULL),
66 _inc_bytes_used_before(0),
67 _inc_recorded_rs_lengths(0),
68 _inc_recorded_rs_lengths_diffs(0),
69 _inc_predicted_elapsed_time_ms(0.0),
70 _inc_predicted_elapsed_time_ms_diffs(0.0),
71 _inc_region_length(0) {}
72
73 G1CollectionSet::~G1CollectionSet() {
74 delete _cset_chooser;
75 }
76
77 void G1CollectionSet::init_region_lengths(uint eden_cset_region_length,
78 uint survivor_cset_region_length) {
79 _eden_region_length = eden_cset_region_length;
80 _survivor_region_length = survivor_cset_region_length;
81
82 assert(young_region_length() == _inc_region_length, "should match %u == %u", young_region_length(), _inc_region_length);
83
84 _old_region_length = 0;
85 }
86
87 void G1CollectionSet::set_recorded_rs_lengths(size_t rs_lengths) {
88 _recorded_rs_lengths = rs_lengths;
89 }
90
91 // Add the heap region at the head of the non-incremental collection set
92 void G1CollectionSet::add_old_region(HeapRegion* hr) {
93 assert(_inc_build_state == Active, "Precondition");
94 assert(hr->is_old(), "the region should be old");
95
96 assert(!hr->in_collection_set(), "should not already be in the CSet");
97 _g1->register_old_region_with_cset(hr);
98 hr->set_next_in_collection_set(_head);
99 _head = hr;
100 _bytes_used_before += hr->used();
101 size_t rs_length = hr->rem_set()->occupied();
102 _recorded_rs_lengths += rs_length;
103 _old_region_length += 1;
104 }
105
106 // Initialize the per-collection-set information
107 void G1CollectionSet::start_incremental_building() {
108 assert(_inc_build_state == Inactive, "Precondition");
109
110 _inc_head = NULL;
111 _inc_tail = NULL;
112 _inc_bytes_used_before = 0;
113 _inc_region_length = 0;
114
115 _inc_recorded_rs_lengths = 0;
116 _inc_recorded_rs_lengths_diffs = 0;
117 _inc_predicted_elapsed_time_ms = 0.0;
118 _inc_predicted_elapsed_time_ms_diffs = 0.0;
119 _inc_build_state = Active;
120 }
121
122 void G1CollectionSet::finalize_incremental_building() {
123 assert(_inc_build_state == Active, "Precondition");
124 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
125
126 // The two "main" fields, _inc_recorded_rs_lengths and
127 // _inc_predicted_elapsed_time_ms, are updated by the thread
128 // that adds a new region to the CSet. Further updates by the
129 // concurrent refinement thread that samples the young RSet lengths
130 // are accumulated in the *_diffs fields. Here we add the diffs to
131 // the "main" fields.
132
133 if (_inc_recorded_rs_lengths_diffs >= 0) {
134 _inc_recorded_rs_lengths += _inc_recorded_rs_lengths_diffs;
135 } else {
136 // This is defensive. The diff should in theory be always positive
137 // as RSets can only grow between GCs. However, given that we
138 // sample their size concurrently with other threads updating them
139 // it's possible that we might get the wrong size back, which
140 // could make the calculations somewhat inaccurate.
141 size_t diffs = (size_t) (-_inc_recorded_rs_lengths_diffs);
142 if (_inc_recorded_rs_lengths >= diffs) {
143 _inc_recorded_rs_lengths -= diffs;
144 } else {
145 _inc_recorded_rs_lengths = 0;
146 }
147 }
148 _inc_predicted_elapsed_time_ms += _inc_predicted_elapsed_time_ms_diffs;
149
150 _inc_recorded_rs_lengths_diffs = 0;
151 _inc_predicted_elapsed_time_ms_diffs = 0.0;
152 }
153
154 void G1CollectionSet::update_young_region_prediction(HeapRegion* hr,
155 size_t new_rs_length) {
156 // Update the CSet information that is dependent on the new RS length
157 assert(hr->is_young(), "Precondition");
158 assert(!SafepointSynchronize::is_at_safepoint(), "should not be at a safepoint");
159
160 // We could have updated _inc_recorded_rs_lengths and
161 // _inc_predicted_elapsed_time_ms directly but we'd need to do
162 // that atomically, as this code is executed by a concurrent
163 // refinement thread, potentially concurrently with a mutator thread
164 // allocating a new region and also updating the same fields. To
165 // avoid the atomic operations we accumulate these updates on two
166 // separate fields (*_diffs) and we'll just add them to the "main"
167 // fields at the start of a GC.
168
169 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
170 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
171 _inc_recorded_rs_lengths_diffs += rs_lengths_diff;
172
173 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
174 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr);
175 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
176 _inc_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
177
178 hr->set_recorded_rs_length(new_rs_length);
179 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
180 }
181
182 void G1CollectionSet::add_young_region_common(HeapRegion* hr) {
183 assert(hr->is_young(), "invariant");
184 assert(_inc_build_state == Active, "Precondition");
185
186 hr->set_young_index_in_cset(_inc_region_length);
187 _inc_region_length++;
188
189 // This routine is used when:
190 // * adding survivor regions to the incremental cset at the end of an
191 // evacuation pause or
192 // * adding the current allocation region to the incremental cset
193 // when it is retired.
194 // Therefore this routine may be called at a safepoint by the
195 // VM thread, or in-between safepoints by mutator threads (when
196 // retiring the current allocation region)
197 // We need to clear and set the cached recorded/cached collection set
198 // information in the heap region here (before the region gets added
199 // to the collection set). An individual heap region's cached values
200 // are calculated, aggregated with the policy collection set info,
201 // and cached in the heap region here (initially) and (subsequently)
202 // by the Young List sampling code.
203
204 size_t rs_length = hr->rem_set()->occupied();
205 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr);
206
207 // Cache the values we have added to the aggregated information
208 // in the heap region in case we have to remove this region from
209 // the incremental collection set, or it is updated by the
210 // rset sampling code
211 hr->set_recorded_rs_length(rs_length);
212 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
213
214 size_t used_bytes = hr->used();
215 _inc_recorded_rs_lengths += rs_length;
216 _inc_predicted_elapsed_time_ms += region_elapsed_time_ms;
217 _inc_bytes_used_before += used_bytes;
218
219 assert(!hr->in_collection_set(), "invariant");
220 _g1->register_young_region_with_cset(hr);
221 assert(hr->next_in_collection_set() == NULL, "invariant");
222 }
223
224 // Add the region at the RHS of the incremental cset
225 void G1CollectionSet::add_survivor_regions(HeapRegion* hr) {
226 // We should only ever be appending survivors at the end of a pause
227 assert(hr->is_survivor(), "Logic");
228
229 // Do the 'common' stuff
230 add_young_region_common(hr);
231
232 // Now add the region at the right hand side
233 if (_inc_tail == NULL) {
234 assert(_inc_head == NULL, "invariant");
235 _inc_head = hr;
236 } else {
237 _inc_tail->set_next_in_collection_set(hr);
238 }
239 _inc_tail = hr;
240 }
241
242 // Add the region to the LHS of the incremental cset
243 void G1CollectionSet::add_eden_region(HeapRegion* hr) {
244 // Survivors should be added to the RHS at the end of a pause
245 assert(hr->is_eden(), "Logic");
246
247 // Do the 'common' stuff
248 add_young_region_common(hr);
249
250 // Add the region at the left hand side
251 hr->set_next_in_collection_set(_inc_head);
252 if (_inc_head == NULL) {
253 assert(_inc_tail == NULL, "Invariant");
254 _inc_tail = hr;
255 }
256 _inc_head = hr;
257 }
258
259 #ifndef PRODUCT
260 void G1CollectionSet::print(HeapRegion* list_head, outputStream* st) {
261 assert(list_head == inc_head() || list_head == head(), "must be");
262
263 st->print_cr("\nCollection_set:");
264 HeapRegion* csr = list_head;
265 while (csr != NULL) {
266 HeapRegion* next = csr->next_in_collection_set();
267 assert(csr->in_collection_set(), "bad CS");
268 st->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT "N: " PTR_FORMAT ", age: %4d",
269 HR_FORMAT_PARAMS(csr),
270 p2i(csr->prev_top_at_mark_start()), p2i(csr->next_top_at_mark_start()),
271 csr->age_in_surv_rate_group_cond());
272 csr = next;
273 }
274 }
275 #endif // !PRODUCT
276
277 double G1CollectionSet::finalize_young_part(double target_pause_time_ms, G1SurvivorRegions* survivors) {
278 double young_start_time_sec = os::elapsedTime();
279
280 finalize_incremental_building();
281
282 guarantee(target_pause_time_ms > 0.0,
283 "target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms);
284 guarantee(_head == NULL, "Precondition");
285
286 size_t pending_cards = _policy->pending_cards();
287 double base_time_ms = _policy->predict_base_elapsed_time_ms(pending_cards);
288 double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
289
290 log_trace(gc, ergo, cset)("Start choosing CSet. pending cards: " SIZE_FORMAT " predicted base time: %1.2fms remaining time: %1.2fms target pause time: %1.2fms",
291 pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
292
293 collector_state()->set_last_gc_was_young(collector_state()->gcs_are_young());
294
295 // The young list is laid with the survivor regions from the previous
296 // pause are appended to the RHS of the young list, i.e.
297 // [Newly Young Regions ++ Survivors from last pause].
298
299 uint survivor_region_length = survivors->length();
300 uint eden_region_length = _g1->eden_regions_count();
301 init_region_lengths(eden_region_length, survivor_region_length);
302
303 verify_young_cset_indices();
304
305 // Clear the fields that point to the survivor list - they are all young now.
306 survivors->convert_to_eden();
307
308 _head = _inc_head;
309 _bytes_used_before = _inc_bytes_used_before;
310 time_remaining_ms = MAX2(time_remaining_ms - _inc_predicted_elapsed_time_ms, 0.0);
311
312 log_trace(gc, ergo, cset)("Add young regions to CSet. eden: %u regions, survivors: %u regions, predicted young region time: %1.2fms, target pause time: %1.2fms",
313 eden_region_length, survivor_region_length, _inc_predicted_elapsed_time_ms, target_pause_time_ms);
314
315 // The number of recorded young regions is the incremental
316 // collection set's current size
317 set_recorded_rs_lengths(_inc_recorded_rs_lengths);
318
319 double young_end_time_sec = os::elapsedTime();
320 phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
321
322 return time_remaining_ms;
323 }
324
325 void G1CollectionSet::finalize_old_part(double time_remaining_ms) {
326 double non_young_start_time_sec = os::elapsedTime();
327 double predicted_old_time_ms = 0.0;
328
406 // avoid generating output per region.
407 log_debug(gc, ergo, cset)("Added expensive regions to CSet (old CSet region num not reached min)."
408 "old: %u regions, expensive: %u regions, min: %u regions, remaining time: %1.2fms",
409 old_region_length(), expensive_region_num, min_old_cset_length, time_remaining_ms);
410 }
411
412 cset_chooser()->verify();
413 }
414
415 stop_incremental_building();
416
417 log_debug(gc, ergo, cset)("Finish choosing CSet. old: %u regions, predicted old region time: %1.2fms, time remaining: %1.2f",
418 old_region_length(), predicted_old_time_ms, time_remaining_ms);
419
420 double non_young_end_time_sec = os::elapsedTime();
421 phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
422 }
423
424 #ifdef ASSERT
425 void G1CollectionSet::verify_young_cset_indices() const {
426 ResourceMark rm;
427 uint* heap_region_indices = NEW_RESOURCE_ARRAY(uint, young_region_length());
428 for (uint i = 0; i < young_region_length(); ++i) {
429 heap_region_indices[i] = (uint)-1;
430 }
431
432 for (HeapRegion* hr = _inc_head; hr != NULL; hr = hr->next_in_collection_set()) {
433 const int idx = hr->young_index_in_cset();
434 assert(idx > -1, "must be set for all inc cset regions");
435 assert((uint)idx < young_region_length(), "young cset index too large");
436
437 assert(heap_region_indices[idx] == (uint)-1,
438 "index %d used by multiple regions, first use by %u, second by %u",
439 idx, heap_region_indices[idx], hr->hrm_index());
440
441 heap_region_indices[idx] = hr->hrm_index();
442 }
443 }
444 #endif
|
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.hpp"
27 #include "gc/g1/g1CollectionSet.hpp"
28 #include "gc/g1/g1CollectorState.hpp"
29 #include "gc/g1/g1Policy.hpp"
30 #include "gc/g1/heapRegion.inline.hpp"
31 #include "gc/g1/heapRegionRemSet.hpp"
32 #include "gc/g1/heapRegionSet.hpp"
33 #include "logging/logStream.hpp"
34 #include "utilities/debug.hpp"
35
36 G1CollectorState* G1CollectionSet::collector_state() {
37 return _g1->collector_state();
38 }
39
40 G1GCPhaseTimes* G1CollectionSet::phase_times() {
41 return _policy->phase_times();
42 }
43
44 CollectionSetChooser* G1CollectionSet::cset_chooser() {
45 return _cset_chooser;
46 }
47
48 double G1CollectionSet::predict_region_elapsed_time_ms(HeapRegion* hr) {
49 return _policy->predict_region_elapsed_time_ms(hr, collector_state()->gcs_are_young());
50 }
51
52 G1CollectionSet::G1CollectionSet(G1CollectedHeap* g1h, G1Policy* policy) :
53 _g1(g1h),
54 _policy(policy),
55 _cset_chooser(new CollectionSetChooser()),
56 _eden_region_length(0),
57 _survivor_region_length(0),
58 _old_region_length(0),
59 _bytes_used_before(0),
60 _recorded_rs_lengths(0),
61 _collection_set_regions(NULL),
62 _collection_set_cur_length(0),
63 _collection_set_max_length(0),
64 // Incremental CSet attributes
65 _inc_build_state(Inactive),
66 _inc_bytes_used_before(0),
67 _inc_recorded_rs_lengths(0),
68 _inc_recorded_rs_lengths_diffs(0),
69 _inc_predicted_elapsed_time_ms(0.0),
70 _inc_predicted_elapsed_time_ms_diffs(0.0) {
71 }
72
73 G1CollectionSet::~G1CollectionSet() {
74 if (_collection_set_regions != NULL) {
75 FREE_C_HEAP_ARRAY(uint, _collection_set_regions);
76 }
77 delete _cset_chooser;
78 }
79
80 void G1CollectionSet::init_region_lengths(uint eden_cset_region_length,
81 uint survivor_cset_region_length) {
82 assert_at_safepoint(true);
83
84 _eden_region_length = eden_cset_region_length;
85 _survivor_region_length = survivor_cset_region_length;
86
87 assert((size_t) young_region_length() == _collection_set_cur_length,
88 "Young region length %u should match collection set length " SIZE_FORMAT, young_region_length(), _collection_set_cur_length);
89
90 _old_region_length = 0;
91 }
92
93 void G1CollectionSet::set_max_length(uint max_region_length) {
94 guarantee(_collection_set_regions == NULL, "Must only initialize once.");
95 _collection_set_max_length = max_region_length;
96 _collection_set_regions = NEW_C_HEAP_ARRAY(uint, max_region_length, mtGC);
97 }
98
99 void G1CollectionSet::set_recorded_rs_lengths(size_t rs_lengths) {
100 _recorded_rs_lengths = rs_lengths;
101 }
102
103 // Add the heap region at the head of the non-incremental collection set
104 void G1CollectionSet::add_old_region(HeapRegion* hr) {
105 assert_at_safepoint(true);
106
107 assert(_inc_build_state == Active, "Precondition");
108 assert(hr->is_old(), "the region should be old");
109
110 assert(!hr->in_collection_set(), "should not already be in the CSet");
111 _g1->register_old_region_with_cset(hr);
112
113 _collection_set_regions[_collection_set_cur_length++] = hr->hrm_index();
114 assert(_collection_set_cur_length <= _collection_set_max_length, "Collection set now larger than maximum size.");
115
116 _bytes_used_before += hr->used();
117 size_t rs_length = hr->rem_set()->occupied();
118 _recorded_rs_lengths += rs_length;
119 _old_region_length += 1;
120 }
121
122 // Initialize the per-collection-set information
123 void G1CollectionSet::start_incremental_building() {
124 assert(_collection_set_cur_length == 0, "Collection set must be empty before starting a new collection set.");
125 assert(_inc_build_state == Inactive, "Precondition");
126
127 _inc_bytes_used_before = 0;
128
129 _inc_recorded_rs_lengths = 0;
130 _inc_recorded_rs_lengths_diffs = 0;
131 _inc_predicted_elapsed_time_ms = 0.0;
132 _inc_predicted_elapsed_time_ms_diffs = 0.0;
133 _inc_build_state = Active;
134 }
135
136 void G1CollectionSet::finalize_incremental_building() {
137 assert(_inc_build_state == Active, "Precondition");
138 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
139
140 // The two "main" fields, _inc_recorded_rs_lengths and
141 // _inc_predicted_elapsed_time_ms, are updated by the thread
142 // that adds a new region to the CSet. Further updates by the
143 // concurrent refinement thread that samples the young RSet lengths
144 // are accumulated in the *_diffs fields. Here we add the diffs to
145 // the "main" fields.
146
147 if (_inc_recorded_rs_lengths_diffs >= 0) {
148 _inc_recorded_rs_lengths += _inc_recorded_rs_lengths_diffs;
149 } else {
150 // This is defensive. The diff should in theory be always positive
151 // as RSets can only grow between GCs. However, given that we
152 // sample their size concurrently with other threads updating them
153 // it's possible that we might get the wrong size back, which
154 // could make the calculations somewhat inaccurate.
155 size_t diffs = (size_t) (-_inc_recorded_rs_lengths_diffs);
156 if (_inc_recorded_rs_lengths >= diffs) {
157 _inc_recorded_rs_lengths -= diffs;
158 } else {
159 _inc_recorded_rs_lengths = 0;
160 }
161 }
162 _inc_predicted_elapsed_time_ms += _inc_predicted_elapsed_time_ms_diffs;
163
164 _inc_recorded_rs_lengths_diffs = 0;
165 _inc_predicted_elapsed_time_ms_diffs = 0.0;
166 }
167
168 void G1CollectionSet::clear() {
169 assert_at_safepoint(true);
170 _collection_set_cur_length = 0;
171 }
172
173 void G1CollectionSet::iterate(HeapRegionClosure* cl, bool may_be_aborted) {
174 iterate_from(cl, 0, 1, may_be_aborted);
175 }
176
177 void G1CollectionSet::iterate_from(HeapRegionClosure* cl, uint worker_id, uint total_workers, bool may_be_aborted) {
178 size_t len = _collection_set_cur_length;
179 OrderAccess::loadload();
180 if (len == 0) {
181 return;
182 }
183 size_t start_pos = (worker_id * len) / total_workers;
184 size_t cur_pos = start_pos;
185
186 do {
187 HeapRegion* r = G1CollectedHeap::heap()->region_at(_collection_set_regions[cur_pos]);
188 bool result = cl->doHeapRegion(r);
189 guarantee(may_be_aborted || !result, "This iteration should not abort.");
190 if (result) {
191 cl->incomplete();
192 return;
193 }
194 cur_pos++;
195 if (cur_pos == len) {
196 cur_pos = 0;
197 }
198 } while (cur_pos != start_pos);
199 }
200
201 void G1CollectionSet::update_young_region_prediction(HeapRegion* hr,
202 size_t new_rs_length) {
203 // Update the CSet information that is dependent on the new RS length
204 assert(hr->is_young(), "Precondition");
205 assert(!SafepointSynchronize::is_at_safepoint(), "should not be at a safepoint");
206
207 // We could have updated _inc_recorded_rs_lengths and
208 // _inc_predicted_elapsed_time_ms directly but we'd need to do
209 // that atomically, as this code is executed by a concurrent
210 // refinement thread, potentially concurrently with a mutator thread
211 // allocating a new region and also updating the same fields. To
212 // avoid the atomic operations we accumulate these updates on two
213 // separate fields (*_diffs) and we'll just add them to the "main"
214 // fields at the start of a GC.
215
216 ssize_t old_rs_length = (ssize_t) hr->recorded_rs_length();
217 ssize_t rs_lengths_diff = (ssize_t) new_rs_length - old_rs_length;
218 _inc_recorded_rs_lengths_diffs += rs_lengths_diff;
219
220 double old_elapsed_time_ms = hr->predicted_elapsed_time_ms();
221 double new_region_elapsed_time_ms = predict_region_elapsed_time_ms(hr);
222 double elapsed_ms_diff = new_region_elapsed_time_ms - old_elapsed_time_ms;
223 _inc_predicted_elapsed_time_ms_diffs += elapsed_ms_diff;
224
225 hr->set_recorded_rs_length(new_rs_length);
226 hr->set_predicted_elapsed_time_ms(new_region_elapsed_time_ms);
227 }
228
229 void G1CollectionSet::add_young_region_common(HeapRegion* hr) {
230 assert(hr->is_young(), "invariant");
231 assert(_inc_build_state == Active, "Precondition");
232
233 size_t collection_set_length = _collection_set_cur_length;
234 assert(collection_set_length <= INT_MAX, "Collection set is too large with %d entries", (int)collection_set_length);
235 hr->set_young_index_in_cset((int)collection_set_length);
236
237 _collection_set_regions[_collection_set_cur_length] = hr->hrm_index();
238 // Concurrent readers must observe the store of the value in the array before an
239 // update to the length field.
240 OrderAccess::storestore();
241 _collection_set_cur_length++;
242 assert(_collection_set_cur_length <= _collection_set_max_length, "Collection set larger than maximum allowed.");
243
244 // This routine is used when:
245 // * adding survivor regions to the incremental cset at the end of an
246 // evacuation pause or
247 // * adding the current allocation region to the incremental cset
248 // when it is retired.
249 // Therefore this routine may be called at a safepoint by the
250 // VM thread, or in-between safepoints by mutator threads (when
251 // retiring the current allocation region)
252 // We need to clear and set the cached recorded/cached collection set
253 // information in the heap region here (before the region gets added
254 // to the collection set). An individual heap region's cached values
255 // are calculated, aggregated with the policy collection set info,
256 // and cached in the heap region here (initially) and (subsequently)
257 // by the Young List sampling code.
258
259 size_t rs_length = hr->rem_set()->occupied();
260 double region_elapsed_time_ms = predict_region_elapsed_time_ms(hr);
261
262 // Cache the values we have added to the aggregated information
263 // in the heap region in case we have to remove this region from
264 // the incremental collection set, or it is updated by the
265 // rset sampling code
266 hr->set_recorded_rs_length(rs_length);
267 hr->set_predicted_elapsed_time_ms(region_elapsed_time_ms);
268
269 size_t used_bytes = hr->used();
270 _inc_recorded_rs_lengths += rs_length;
271 _inc_predicted_elapsed_time_ms += region_elapsed_time_ms;
272 _inc_bytes_used_before += used_bytes;
273
274 assert(!hr->in_collection_set(), "invariant");
275 _g1->register_young_region_with_cset(hr);
276 }
277
278 void G1CollectionSet::add_survivor_regions(HeapRegion* hr) {
279 assert(hr->is_survivor(), "Must only add survivor regions, but is %s", hr->get_type_str());
280 add_young_region_common(hr);
281 }
282
283 void G1CollectionSet::add_eden_region(HeapRegion* hr) {
284 assert(hr->is_eden(), "Must only add eden regions, but is %s", hr->get_type_str());
285 add_young_region_common(hr);
286 }
287
288 #ifndef PRODUCT
289 bool G1CollectionSet::verify_young_ages() {
290 assert_at_safepoint(true);
291
292 bool ret = true;
293
294 size_t length = _collection_set_cur_length;
295 for (size_t i = 0; i < length; i++) {
296 HeapRegion* curr = G1CollectedHeap::heap()->region_at(_collection_set_regions[i]);
297
298 guarantee(curr->is_young(), "Region must be young but is %s", curr->get_type_str());
299
300 SurvRateGroup* group = curr->surv_rate_group();
301
302 if (group == NULL) {
303 log_error(gc, verify)("## encountered NULL surv_rate_group in young region");
304 ret = false;
305 }
306
307 if (curr->age_in_surv_rate_group() < 0) {
308 log_error(gc, verify)("## encountered negative age in young region");
309 ret = false;
310 }
311 }
312
313 if (!ret) {
314 LogStreamHandle(Error, gc, verify) log;
315 print(&log);
316 }
317
318 return ret;
319 }
320
321 class G1PrintCollectionSetClosure : public HeapRegionClosure {
322 outputStream* _st;
323 public:
324 G1PrintCollectionSetClosure(outputStream* st) : HeapRegionClosure(), _st(st) { }
325
326 virtual bool doHeapRegion(HeapRegion* r) {
327 assert(r->in_collection_set(), "Region %u should be in collection set", r->hrm_index());
328 _st->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT "N: " PTR_FORMAT ", age: %4d",
329 HR_FORMAT_PARAMS(r),
330 p2i(r->prev_top_at_mark_start()),
331 p2i(r->next_top_at_mark_start()),
332 r->age_in_surv_rate_group_cond());
333 return false;
334 }
335 };
336
337 void G1CollectionSet::print(outputStream* st) {
338 st->print_cr("\nCollection_set:");
339
340 G1PrintCollectionSetClosure cl(st);
341 iterate(&cl);
342 }
343 #endif // !PRODUCT
344
345 double G1CollectionSet::finalize_young_part(double target_pause_time_ms, G1SurvivorRegions* survivors) {
346 double young_start_time_sec = os::elapsedTime();
347
348 finalize_incremental_building();
349
350 guarantee(target_pause_time_ms > 0.0,
351 "target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms);
352
353 size_t pending_cards = _policy->pending_cards();
354 double base_time_ms = _policy->predict_base_elapsed_time_ms(pending_cards);
355 double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
356
357 log_trace(gc, ergo, cset)("Start choosing CSet. pending cards: " SIZE_FORMAT " predicted base time: %1.2fms remaining time: %1.2fms target pause time: %1.2fms",
358 pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
359
360 collector_state()->set_last_gc_was_young(collector_state()->gcs_are_young());
361
362 // The young list is laid with the survivor regions from the previous
363 // pause are appended to the RHS of the young list, i.e.
364 // [Newly Young Regions ++ Survivors from last pause].
365
366 uint survivor_region_length = survivors->length();
367 uint eden_region_length = _g1->eden_regions_count();
368 init_region_lengths(eden_region_length, survivor_region_length);
369
370 verify_young_cset_indices();
371
372 // Clear the fields that point to the survivor list - they are all young now.
373 survivors->convert_to_eden();
374
375 _bytes_used_before = _inc_bytes_used_before;
376 time_remaining_ms = MAX2(time_remaining_ms - _inc_predicted_elapsed_time_ms, 0.0);
377
378 log_trace(gc, ergo, cset)("Add young regions to CSet. eden: %u regions, survivors: %u regions, predicted young region time: %1.2fms, target pause time: %1.2fms",
379 eden_region_length, survivor_region_length, _inc_predicted_elapsed_time_ms, target_pause_time_ms);
380
381 // The number of recorded young regions is the incremental
382 // collection set's current size
383 set_recorded_rs_lengths(_inc_recorded_rs_lengths);
384
385 double young_end_time_sec = os::elapsedTime();
386 phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
387
388 return time_remaining_ms;
389 }
390
391 void G1CollectionSet::finalize_old_part(double time_remaining_ms) {
392 double non_young_start_time_sec = os::elapsedTime();
393 double predicted_old_time_ms = 0.0;
394
472 // avoid generating output per region.
473 log_debug(gc, ergo, cset)("Added expensive regions to CSet (old CSet region num not reached min)."
474 "old: %u regions, expensive: %u regions, min: %u regions, remaining time: %1.2fms",
475 old_region_length(), expensive_region_num, min_old_cset_length, time_remaining_ms);
476 }
477
478 cset_chooser()->verify();
479 }
480
481 stop_incremental_building();
482
483 log_debug(gc, ergo, cset)("Finish choosing CSet. old: %u regions, predicted old region time: %1.2fms, time remaining: %1.2f",
484 old_region_length(), predicted_old_time_ms, time_remaining_ms);
485
486 double non_young_end_time_sec = os::elapsedTime();
487 phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
488 }
489
490 #ifdef ASSERT
491 void G1CollectionSet::verify_young_cset_indices() const {
492 assert_at_safepoint(true);
493
494 ResourceMark rm;
495 uint* heap_region_indices = NEW_RESOURCE_ARRAY(uint, young_region_length());
496 for (uint i = 0; i < young_region_length(); ++i) {
497 heap_region_indices[i] = (uint)-1;
498 }
499
500 size_t length = _collection_set_cur_length;
501 for (size_t i = 0; i < length; i++) {
502 HeapRegion* hr = G1CollectedHeap::heap()->region_at(_collection_set_regions[i]);
503
504 const int idx = hr->young_index_in_cset();
505 assert(idx > -1, "Young index must be set for all regions in the incremental collection set but is not for region %u.", hr->hrm_index());
506 assert((uint)idx < young_region_length(), "Young cset index too large for region %u", hr->hrm_index());
507
508 assert(heap_region_indices[idx] == (uint)-1,
509 "Index %d used by multiple regions, first use by region %u, second by region %u",
510 idx, heap_region_indices[idx], hr->hrm_index());
511
512 heap_region_indices[idx] = hr->hrm_index();
513 }
514 }
515 #endif
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