1 /*
2 * Copyright (c) 2001, 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/concurrentG1Refine.hpp"
27 #include "gc/g1/concurrentG1RefineThread.hpp"
28 #include "gc/g1/g1BlockOffsetTable.inline.hpp"
29 #include "gc/g1/g1CollectedHeap.inline.hpp"
30 #include "gc/g1/g1CollectorPolicy.hpp"
31 #include "gc/g1/g1GCPhaseTimes.hpp"
32 #include "gc/g1/g1HotCardCache.hpp"
33 #include "gc/g1/g1OopClosures.inline.hpp"
34 #include "gc/g1/g1RemSet.inline.hpp"
35 #include "gc/g1/heapRegionManager.inline.hpp"
36 #include "gc/g1/heapRegionRemSet.hpp"
37 #include "memory/iterator.hpp"
38 #include "oops/oop.inline.hpp"
39 #include "utilities/globalDefinitions.hpp"
40 #include "utilities/intHisto.hpp"
41 #include "utilities/stack.inline.hpp"
42
43 #define CARD_REPEAT_HISTO 0
44
45 #if CARD_REPEAT_HISTO
46 static size_t ct_freq_sz;
47 static jbyte* ct_freq = NULL;
48
49 void init_ct_freq_table(size_t heap_sz_bytes) {
50 if (ct_freq == NULL) {
51 ct_freq_sz = heap_sz_bytes/CardTableModRefBS::card_size;
52 ct_freq = new jbyte[ct_freq_sz];
53 for (size_t j = 0; j < ct_freq_sz; j++) ct_freq[j] = 0;
54 }
55 }
56
57 void ct_freq_note_card(size_t index) {
58 assert(0 <= index && index < ct_freq_sz, "Bounds error.");
59 if (ct_freq[index] < 100) { ct_freq[index]++; }
60 }
61
62 static IntHistogram card_repeat_count(10, 10);
63
64 void ct_freq_update_histo_and_reset() {
65 for (size_t j = 0; j < ct_freq_sz; j++) {
66 card_repeat_count.add_entry(ct_freq[j]);
67 ct_freq[j] = 0;
68 }
69
70 }
71 #endif
72
73 G1RemSet::G1RemSet(G1CollectedHeap* g1, CardTableModRefBS* ct_bs)
74 : _g1(g1), _conc_refine_cards(0),
75 _ct_bs(ct_bs), _g1p(_g1->g1_policy()),
76 _cg1r(g1->concurrent_g1_refine()),
77 _cset_rs_update_cl(NULL),
78 _prev_period_summary()
79 {
80 _cset_rs_update_cl = NEW_C_HEAP_ARRAY(G1ParPushHeapRSClosure*, n_workers(), mtGC);
81 for (uint i = 0; i < n_workers(); i++) {
82 _cset_rs_update_cl[i] = NULL;
83 }
84 if (G1SummarizeRSetStats) {
85 _prev_period_summary.initialize(this);
86 }
87 }
88
89 G1RemSet::~G1RemSet() {
90 for (uint i = 0; i < n_workers(); i++) {
91 assert(_cset_rs_update_cl[i] == NULL, "it should be");
92 }
93 FREE_C_HEAP_ARRAY(G1ParPushHeapRSClosure*, _cset_rs_update_cl);
94 }
95
96 class ScanRSClosure : public HeapRegionClosure {
97 size_t _cards_done, _cards;
98 G1CollectedHeap* _g1h;
99
100 G1ParPushHeapRSClosure* _oc;
101 CodeBlobClosure* _code_root_cl;
102
103 G1BlockOffsetSharedArray* _bot_shared;
104 G1SATBCardTableModRefBS *_ct_bs;
105
106 double _strong_code_root_scan_time_sec;
107 uint _worker_i;
108 size_t _block_size;
109 bool _try_claimed;
110
111 public:
112 ScanRSClosure(G1ParPushHeapRSClosure* oc,
113 CodeBlobClosure* code_root_cl,
114 uint worker_i) :
115 _oc(oc),
116 _code_root_cl(code_root_cl),
117 _strong_code_root_scan_time_sec(0.0),
118 _cards(0),
119 _cards_done(0),
120 _worker_i(worker_i),
121 _try_claimed(false)
122 {
123 _g1h = G1CollectedHeap::heap();
124 _bot_shared = _g1h->bot_shared();
125 _ct_bs = _g1h->g1_barrier_set();
126 _block_size = MAX2<size_t>(G1RSetScanBlockSize, 1);
127 }
128
129 void set_try_claimed() { _try_claimed = true; }
130
131 void scanCard(size_t index, HeapRegion *r) {
132 // Stack allocate the DirtyCardToOopClosure instance
133 HeapRegionDCTOC cl(_g1h, r, _oc,
134 CardTableModRefBS::Precise);
135
136 // Set the "from" region in the closure.
137 _oc->set_region(r);
138 MemRegion card_region(_bot_shared->address_for_index(index), G1BlockOffsetSharedArray::N_words);
139 MemRegion pre_gc_allocated(r->bottom(), r->scan_top());
140 MemRegion mr = pre_gc_allocated.intersection(card_region);
141 if (!mr.is_empty() && !_ct_bs->is_card_claimed(index)) {
142 // We make the card as "claimed" lazily (so races are possible
143 // but they're benign), which reduces the number of duplicate
144 // scans (the rsets of the regions in the cset can intersect).
145 _ct_bs->set_card_claimed(index);
146 _cards_done++;
147 cl.do_MemRegion(mr);
148 }
149 }
150
151 void printCard(HeapRegion* card_region, size_t card_index,
152 HeapWord* card_start) {
153 gclog_or_tty->print_cr("T %u Region [" PTR_FORMAT ", " PTR_FORMAT ") "
154 "RS names card " SIZE_FORMAT_HEX ": "
155 "[" PTR_FORMAT ", " PTR_FORMAT ")",
156 _worker_i,
157 p2i(card_region->bottom()), p2i(card_region->end()),
158 card_index,
159 p2i(card_start), p2i(card_start + G1BlockOffsetSharedArray::N_words));
160 }
161
162 void scan_strong_code_roots(HeapRegion* r) {
163 double scan_start = os::elapsedTime();
164 r->strong_code_roots_do(_code_root_cl);
165 _strong_code_root_scan_time_sec += (os::elapsedTime() - scan_start);
166 }
167
168 bool doHeapRegion(HeapRegion* r) {
169 assert(r->in_collection_set(), "should only be called on elements of CS.");
170 HeapRegionRemSet* hrrs = r->rem_set();
171 if (hrrs->iter_is_complete()) return false; // All done.
172 if (!_try_claimed && !hrrs->claim_iter()) return false;
173 // If we ever free the collection set concurrently, we should also
174 // clear the card table concurrently therefore we won't need to
175 // add regions of the collection set to the dirty cards region.
176 _g1h->push_dirty_cards_region(r);
177 // If we didn't return above, then
178 // _try_claimed || r->claim_iter()
179 // is true: either we're supposed to work on claimed-but-not-complete
180 // regions, or we successfully claimed the region.
181
182 HeapRegionRemSetIterator iter(hrrs);
183 size_t card_index;
184
185 // We claim cards in block so as to reduce the contention. The block size is determined by
186 // the G1RSetScanBlockSize parameter.
187 size_t jump_to_card = hrrs->iter_claimed_next(_block_size);
188 for (size_t current_card = 0; iter.has_next(card_index); current_card++) {
189 if (current_card >= jump_to_card + _block_size) {
190 jump_to_card = hrrs->iter_claimed_next(_block_size);
191 }
192 if (current_card < jump_to_card) continue;
193 HeapWord* card_start = _g1h->bot_shared()->address_for_index(card_index);
194 #if 0
195 gclog_or_tty->print("Rem set iteration yielded card [" PTR_FORMAT ", " PTR_FORMAT ").\n",
196 card_start, card_start + CardTableModRefBS::card_size_in_words);
197 #endif
198
199 HeapRegion* card_region = _g1h->heap_region_containing(card_start);
200 _cards++;
201
202 if (!card_region->is_on_dirty_cards_region_list()) {
203 _g1h->push_dirty_cards_region(card_region);
204 }
205
206 // If the card is dirty, then we will scan it during updateRS.
207 if (!card_region->in_collection_set() &&
208 !_ct_bs->is_card_dirty(card_index)) {
209 scanCard(card_index, card_region);
210 }
211 }
212 if (!_try_claimed) {
213 // Scan the strong code root list attached to the current region
214 scan_strong_code_roots(r);
215
216 hrrs->set_iter_complete();
217 }
218 return false;
219 }
220
221 double strong_code_root_scan_time_sec() {
222 return _strong_code_root_scan_time_sec;
223 }
224
225 size_t cards_done() { return _cards_done;}
226 size_t cards_looked_up() { return _cards;}
227 };
228
229 size_t G1RemSet::scanRS(G1ParPushHeapRSClosure* oc,
230 CodeBlobClosure* heap_region_codeblobs,
231 uint worker_i) {
232 double rs_time_start = os::elapsedTime();
233
234 HeapRegion *startRegion = _g1->start_cset_region_for_worker(worker_i);
235
236 ScanRSClosure scanRScl(oc, heap_region_codeblobs, worker_i);
237
238 _g1->collection_set_iterate_from(startRegion, &scanRScl);
239 scanRScl.set_try_claimed();
240 _g1->collection_set_iterate_from(startRegion, &scanRScl);
241
242 double scan_rs_time_sec = (os::elapsedTime() - rs_time_start)
243 - scanRScl.strong_code_root_scan_time_sec();
244
245 _g1p->phase_times()->record_time_secs(G1GCPhaseTimes::ScanRS, worker_i, scan_rs_time_sec);
246 _g1p->phase_times()->record_time_secs(G1GCPhaseTimes::CodeRoots, worker_i, scanRScl.strong_code_root_scan_time_sec());
247
248 return scanRScl.cards_done();
249 }
250
251 // Closure used for updating RSets and recording references that
252 // point into the collection set. Only called during an
253 // evacuation pause.
254
255 class RefineRecordRefsIntoCSCardTableEntryClosure: public CardTableEntryClosure {
256 G1RemSet* _g1rs;
257 DirtyCardQueue* _into_cset_dcq;
258 public:
259 RefineRecordRefsIntoCSCardTableEntryClosure(G1CollectedHeap* g1h,
260 DirtyCardQueue* into_cset_dcq) :
261 _g1rs(g1h->g1_rem_set()), _into_cset_dcq(into_cset_dcq)
262 {}
263 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
264 // The only time we care about recording cards that
265 // contain references that point into the collection set
266 // is during RSet updating within an evacuation pause.
267 // In this case worker_i should be the id of a GC worker thread.
268 assert(SafepointSynchronize::is_at_safepoint(), "not during an evacuation pause");
269 assert(worker_i < ParallelGCThreads, "should be a GC worker");
270
271 if (_g1rs->refine_card(card_ptr, worker_i, true)) {
272 // 'card_ptr' contains references that point into the collection
273 // set. We need to record the card in the DCQS
274 // (G1CollectedHeap::into_cset_dirty_card_queue_set())
275 // that's used for that purpose.
276 //
277 // Enqueue the card
278 _into_cset_dcq->enqueue(card_ptr);
279 }
280 return true;
281 }
282 };
283
284 void G1RemSet::updateRS(DirtyCardQueue* into_cset_dcq, uint worker_i) {
285 G1GCParPhaseTimesTracker x(_g1p->phase_times(), G1GCPhaseTimes::UpdateRS, worker_i);
286 // Apply the given closure to all remaining log entries.
287 RefineRecordRefsIntoCSCardTableEntryClosure into_cset_update_rs_cl(_g1, into_cset_dcq);
288
289 _g1->iterate_dirty_card_closure(&into_cset_update_rs_cl, into_cset_dcq, false, worker_i);
290 }
291
292 void G1RemSet::cleanupHRRS() {
293 HeapRegionRemSet::cleanup();
294 }
295
296 size_t G1RemSet::oops_into_collection_set_do(G1ParPushHeapRSClosure* oc,
297 CodeBlobClosure* heap_region_codeblobs,
298 uint worker_i) {
299 #if CARD_REPEAT_HISTO
300 ct_freq_update_histo_and_reset();
301 #endif
302
303 // We cache the value of 'oc' closure into the appropriate slot in the
304 // _cset_rs_update_cl for this worker
305 assert(worker_i < n_workers(), "sanity");
306 _cset_rs_update_cl[worker_i] = oc;
307
308 // A DirtyCardQueue that is used to hold cards containing references
309 // that point into the collection set. This DCQ is associated with a
310 // special DirtyCardQueueSet (see g1CollectedHeap.hpp). Under normal
311 // circumstances (i.e. the pause successfully completes), these cards
312 // are just discarded (there's no need to update the RSets of regions
313 // that were in the collection set - after the pause these regions
314 // are wholly 'free' of live objects. In the event of an evacuation
315 // failure the cards/buffers in this queue set are passed to the
316 // DirtyCardQueueSet that is used to manage RSet updates
317 DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set());
318
319 updateRS(&into_cset_dcq, worker_i);
320 size_t cards_scanned = scanRS(oc, heap_region_codeblobs, worker_i);
321
322 // We now clear the cached values of _cset_rs_update_cl for this worker
323 _cset_rs_update_cl[worker_i] = NULL;
324 return cards_scanned;
325 }
326
327 void G1RemSet::prepare_for_oops_into_collection_set_do() {
328 cleanupHRRS();
329 _g1->set_refine_cte_cl_concurrency(false);
330 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
331 dcqs.concatenate_logs();
332 }
333
334 void G1RemSet::cleanup_after_oops_into_collection_set_do() {
335 // Cleanup after copy
336 _g1->set_refine_cte_cl_concurrency(true);
337 // Set all cards back to clean.
338 _g1->cleanUpCardTable();
339
340 DirtyCardQueueSet& into_cset_dcqs = _g1->into_cset_dirty_card_queue_set();
341 int into_cset_n_buffers = into_cset_dcqs.completed_buffers_num();
342
343 if (_g1->evacuation_failed()) {
344 double restore_remembered_set_start = os::elapsedTime();
345
346 // Restore remembered sets for the regions pointing into the collection set.
347 // We just need to transfer the completed buffers from the DirtyCardQueueSet
348 // used to hold cards that contain references that point into the collection set
349 // to the DCQS used to hold the deferred RS updates.
350 _g1->dirty_card_queue_set().merge_bufferlists(&into_cset_dcqs);
351 _g1->g1_policy()->phase_times()->record_evac_fail_restore_remsets((os::elapsedTime() - restore_remembered_set_start) * 1000.0);
352 }
353
354 // Free any completed buffers in the DirtyCardQueueSet used to hold cards
355 // which contain references that point into the collection.
356 _g1->into_cset_dirty_card_queue_set().clear();
357 assert(_g1->into_cset_dirty_card_queue_set().completed_buffers_num() == 0,
358 "all buffers should be freed");
359 _g1->into_cset_dirty_card_queue_set().clear_n_completed_buffers();
360 }
361
362 class ScrubRSClosure: public HeapRegionClosure {
363 G1CollectedHeap* _g1h;
364 BitMap* _region_bm;
365 BitMap* _card_bm;
366 CardTableModRefBS* _ctbs;
367 public:
368 ScrubRSClosure(BitMap* region_bm, BitMap* card_bm) :
369 _g1h(G1CollectedHeap::heap()),
370 _region_bm(region_bm), _card_bm(card_bm),
371 _ctbs(_g1h->g1_barrier_set()) {}
372
373 bool doHeapRegion(HeapRegion* r) {
374 if (!r->is_continues_humongous()) {
375 r->rem_set()->scrub(_ctbs, _region_bm, _card_bm);
376 }
377 return false;
378 }
379 };
380
381 void G1RemSet::scrub(BitMap* region_bm, BitMap* card_bm, uint worker_num, HeapRegionClaimer *hrclaimer) {
382 ScrubRSClosure scrub_cl(region_bm, card_bm);
383 _g1->heap_region_par_iterate(&scrub_cl, worker_num, hrclaimer);
384 }
385
386 G1TriggerClosure::G1TriggerClosure() :
387 _triggered(false) { }
388
389 G1InvokeIfNotTriggeredClosure::G1InvokeIfNotTriggeredClosure(G1TriggerClosure* t_cl,
390 OopClosure* oop_cl) :
391 _trigger_cl(t_cl), _oop_cl(oop_cl) { }
392
393 G1Mux2Closure::G1Mux2Closure(OopClosure *c1, OopClosure *c2) :
394 _c1(c1), _c2(c2) { }
395
396 G1UpdateRSOrPushRefOopClosure::
397 G1UpdateRSOrPushRefOopClosure(G1CollectedHeap* g1h,
398 G1RemSet* rs,
399 G1ParPushHeapRSClosure* push_ref_cl,
400 bool record_refs_into_cset,
401 uint worker_i) :
402 _g1(g1h), _g1_rem_set(rs), _from(NULL),
403 _record_refs_into_cset(record_refs_into_cset),
404 _push_ref_cl(push_ref_cl), _worker_i(worker_i) { }
405
406 // Returns true if the given card contains references that point
407 // into the collection set, if we're checking for such references;
408 // false otherwise.
409
410 bool G1RemSet::refine_card(jbyte* card_ptr, uint worker_i,
411 bool check_for_refs_into_cset) {
412 assert(_g1->is_in_exact(_ct_bs->addr_for(card_ptr)),
413 "Card at " PTR_FORMAT " index " SIZE_FORMAT " representing heap at " PTR_FORMAT " (%u) must be in committed heap",
414 p2i(card_ptr),
415 _ct_bs->index_for(_ct_bs->addr_for(card_ptr)),
416 p2i(_ct_bs->addr_for(card_ptr)),
417 _g1->addr_to_region(_ct_bs->addr_for(card_ptr)));
418
419 // If the card is no longer dirty, nothing to do.
420 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
421 // No need to return that this card contains refs that point
422 // into the collection set.
423 return false;
424 }
425
426 // Construct the region representing the card.
427 HeapWord* start = _ct_bs->addr_for(card_ptr);
428 // And find the region containing it.
429 HeapRegion* r = _g1->heap_region_containing(start);
430
431 // Why do we have to check here whether a card is on a young region,
432 // given that we dirty young regions and, as a result, the
433 // post-barrier is supposed to filter them out and never to enqueue
434 // them? When we allocate a new region as the "allocation region" we
435 // actually dirty its cards after we release the lock, since card
436 // dirtying while holding the lock was a performance bottleneck. So,
437 // as a result, it is possible for other threads to actually
438 // allocate objects in the region (after the acquire the lock)
439 // before all the cards on the region are dirtied. This is unlikely,
440 // and it doesn't happen often, but it can happen. So, the extra
441 // check below filters out those cards.
442 if (r->is_young()) {
443 return false;
444 }
445
446 // While we are processing RSet buffers during the collection, we
447 // actually don't want to scan any cards on the collection set,
448 // since we don't want to update remembered sets with entries that
449 // point into the collection set, given that live objects from the
450 // collection set are about to move and such entries will be stale
451 // very soon. This change also deals with a reliability issue which
452 // involves scanning a card in the collection set and coming across
453 // an array that was being chunked and looking malformed. Note,
454 // however, that if evacuation fails, we have to scan any objects
455 // that were not moved and create any missing entries.
456 if (r->in_collection_set()) {
457 return false;
458 }
459
460 // The result from the hot card cache insert call is either:
461 // * pointer to the current card
462 // (implying that the current card is not 'hot'),
463 // * null
464 // (meaning we had inserted the card ptr into the "hot" card cache,
465 // which had some headroom),
466 // * a pointer to a "hot" card that was evicted from the "hot" cache.
467 //
468
469 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
470 if (hot_card_cache->use_cache()) {
471 assert(!check_for_refs_into_cset, "sanity");
472 assert(!SafepointSynchronize::is_at_safepoint(), "sanity");
473
474 card_ptr = hot_card_cache->insert(card_ptr);
475 if (card_ptr == NULL) {
476 // There was no eviction. Nothing to do.
477 return false;
478 }
479
480 start = _ct_bs->addr_for(card_ptr);
481 r = _g1->heap_region_containing(start);
482
483 // Checking whether the region we got back from the cache
484 // is young here is inappropriate. The region could have been
485 // freed, reallocated and tagged as young while in the cache.
486 // Hence we could see its young type change at any time.
487 }
488
489 // Don't use addr_for(card_ptr + 1) which can ask for
490 // a card beyond the heap. This is not safe without a perm
491 // gen at the upper end of the heap.
492 HeapWord* end = start + CardTableModRefBS::card_size_in_words;
493 MemRegion dirtyRegion(start, end);
494
495 #if CARD_REPEAT_HISTO
496 init_ct_freq_table(_g1->max_capacity());
497 ct_freq_note_card(_ct_bs->index_for(start));
498 #endif
499
500 G1ParPushHeapRSClosure* oops_in_heap_closure = NULL;
501 if (check_for_refs_into_cset) {
502 // ConcurrentG1RefineThreads have worker numbers larger than what
503 // _cset_rs_update_cl[] is set up to handle. But those threads should
504 // only be active outside of a collection which means that when they
505 // reach here they should have check_for_refs_into_cset == false.
506 assert((size_t)worker_i < n_workers(), "index of worker larger than _cset_rs_update_cl[].length");
507 oops_in_heap_closure = _cset_rs_update_cl[worker_i];
508 }
509 G1UpdateRSOrPushRefOopClosure update_rs_oop_cl(_g1,
510 _g1->g1_rem_set(),
511 oops_in_heap_closure,
512 check_for_refs_into_cset,
513 worker_i);
514 update_rs_oop_cl.set_from(r);
515
516 G1TriggerClosure trigger_cl;
517 FilterIntoCSClosure into_cs_cl(NULL, _g1, &trigger_cl);
518 G1InvokeIfNotTriggeredClosure invoke_cl(&trigger_cl, &into_cs_cl);
519 G1Mux2Closure mux(&invoke_cl, &update_rs_oop_cl);
520
521 FilterOutOfRegionClosure filter_then_update_rs_oop_cl(r,
522 (check_for_refs_into_cset ?
523 (OopClosure*)&mux :
524 (OopClosure*)&update_rs_oop_cl));
525
526 // The region for the current card may be a young region. The
527 // current card may have been a card that was evicted from the
528 // card cache. When the card was inserted into the cache, we had
529 // determined that its region was non-young. While in the cache,
530 // the region may have been freed during a cleanup pause, reallocated
531 // and tagged as young.
532 //
533 // We wish to filter out cards for such a region but the current
534 // thread, if we're running concurrently, may "see" the young type
535 // change at any time (so an earlier "is_young" check may pass or
536 // fail arbitrarily). We tell the iteration code to perform this
537 // filtering when it has been determined that there has been an actual
538 // allocation in this region and making it safe to check the young type.
539 bool filter_young = true;
540
541 HeapWord* stop_point =
542 r->oops_on_card_seq_iterate_careful(dirtyRegion,
543 &filter_then_update_rs_oop_cl,
544 filter_young,
545 card_ptr);
546
547 // If stop_point is non-null, then we encountered an unallocated region
548 // (perhaps the unfilled portion of a TLAB.) For now, we'll dirty the
549 // card and re-enqueue: if we put off the card until a GC pause, then the
550 // unallocated portion will be filled in. Alternatively, we might try
551 // the full complexity of the technique used in "regular" precleaning.
552 if (stop_point != NULL) {
553 // The card might have gotten re-dirtied and re-enqueued while we
554 // worked. (In fact, it's pretty likely.)
555 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
556 *card_ptr = CardTableModRefBS::dirty_card_val();
557 MutexLockerEx x(Shared_DirtyCardQ_lock,
558 Mutex::_no_safepoint_check_flag);
559 DirtyCardQueue* sdcq =
560 JavaThread::dirty_card_queue_set().shared_dirty_card_queue();
561 sdcq->enqueue(card_ptr);
562 }
563 } else {
564 _conc_refine_cards++;
565 }
566
567 // This gets set to true if the card being refined has
568 // references that point into the collection set.
569 bool has_refs_into_cset = trigger_cl.triggered();
570
571 // We should only be detecting that the card contains references
572 // that point into the collection set if the current thread is
573 // a GC worker thread.
574 assert(!has_refs_into_cset || SafepointSynchronize::is_at_safepoint(),
575 "invalid result at non safepoint");
576
577 return has_refs_into_cset;
578 }
579
580 void G1RemSet::print_periodic_summary_info(const char* header) {
581 G1RemSetSummary current;
582 current.initialize(this);
583
584 _prev_period_summary.subtract_from(¤t);
585 print_summary_info(&_prev_period_summary, header);
586
587 _prev_period_summary.set(¤t);
588 }
589
590 void G1RemSet::print_summary_info() {
591 G1RemSetSummary current;
592 current.initialize(this);
593
594 print_summary_info(¤t, " Cumulative RS summary");
595 }
596
597 void G1RemSet::print_summary_info(G1RemSetSummary * summary, const char * header) {
598 assert(summary != NULL, "just checking");
599
600 if (header != NULL) {
601 gclog_or_tty->print_cr("%s", header);
602 }
603
604 #if CARD_REPEAT_HISTO
605 gclog_or_tty->print_cr("\nG1 card_repeat count histogram: ");
606 gclog_or_tty->print_cr(" # of repeats --> # of cards with that number.");
607 card_repeat_count.print_on(gclog_or_tty);
608 #endif
609
610 summary->print_on(gclog_or_tty);
611 }
612
613 void G1RemSet::prepare_for_verify() {
614 if (G1HRRSFlushLogBuffersOnVerify &&
615 (VerifyBeforeGC || VerifyAfterGC)
616 && (!_g1->collector_state()->full_collection() || G1VerifyRSetsDuringFullGC)) {
617 cleanupHRRS();
618 _g1->set_refine_cte_cl_concurrency(false);
619 if (SafepointSynchronize::is_at_safepoint()) {
620 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
621 dcqs.concatenate_logs();
622 }
623
624 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
625 bool use_hot_card_cache = hot_card_cache->use_cache();
626 hot_card_cache->set_use_cache(false);
627
628 DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set());
629 updateRS(&into_cset_dcq, 0);
630 _g1->into_cset_dirty_card_queue_set().clear();
631
632 hot_card_cache->set_use_cache(use_hot_card_cache);
633 assert(JavaThread::dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
634 }
635 }