1 /*
2 * Copyright (c) 2001, 2014, 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/concurrentG1Refine.hpp"
27 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
28 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
29 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
30 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
31 #include "gc_implementation/g1/g1HotCardCache.hpp"
32 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
33 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
34 #include "gc_implementation/g1/g1RemSet.inline.hpp"
35 #include "gc_implementation/g1/heapRegionManager.inline.hpp"
36 #include "gc_implementation/g1/heapRegionRemSet.hpp"
37 #include "memory/iterator.hpp"
38 #include "oops/oop.inline.hpp"
39 #include "utilities/intHisto.hpp"
40
41 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
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 _cards_scanned(NULL), _total_cards_scanned(0),
79 _prev_period_summary()
80 {
81 guarantee(n_workers() > 0, "There should be some workers");
82 _cset_rs_update_cl = NEW_C_HEAP_ARRAY(G1ParPushHeapRSClosure*, n_workers(), mtGC);
83 for (uint i = 0; i < n_workers(); i++) {
84 _cset_rs_update_cl[i] = NULL;
85 }
86 if (G1SummarizeRSetStats) {
87 _prev_period_summary.initialize(this);
88 }
89 }
90
91 G1RemSet::~G1RemSet() {
92 for (uint i = 0; i < n_workers(); i++) {
93 assert(_cset_rs_update_cl[i] == NULL, "it should be");
94 }
95 FREE_C_HEAP_ARRAY(G1ParPushHeapRSClosure*, _cset_rs_update_cl, mtGC);
96 }
97
98 void CountNonCleanMemRegionClosure::do_MemRegion(MemRegion mr) {
99 if (_g1->is_in_g1_reserved(mr.start())) {
100 _n += (int) ((mr.byte_size() / CardTableModRefBS::card_size));
101 if (_start_first == NULL) _start_first = mr.start();
102 }
103 }
104
105 class ScanRSClosure : public HeapRegionClosure {
106 size_t _cards_done, _cards;
107 G1CollectedHeap* _g1h;
108
109 G1ParPushHeapRSClosure* _oc;
110 CodeBlobClosure* _code_root_cl;
111
112 G1BlockOffsetSharedArray* _bot_shared;
113 G1SATBCardTableModRefBS *_ct_bs;
114
115 double _strong_code_root_scan_time_sec;
116 uint _worker_i;
117 int _block_size;
118 bool _try_claimed;
119
120 public:
121 ScanRSClosure(G1ParPushHeapRSClosure* oc,
122 CodeBlobClosure* code_root_cl,
123 uint worker_i) :
124 _oc(oc),
125 _code_root_cl(code_root_cl),
126 _strong_code_root_scan_time_sec(0.0),
127 _cards(0),
128 _cards_done(0),
129 _worker_i(worker_i),
130 _try_claimed(false)
131 {
132 _g1h = G1CollectedHeap::heap();
133 _bot_shared = _g1h->bot_shared();
134 _ct_bs = _g1h->g1_barrier_set();
135 _block_size = MAX2<int>(G1RSetScanBlockSize, 1);
136 }
137
138 void set_try_claimed() { _try_claimed = true; }
139
140 void scanCard(size_t index, HeapRegion *r) {
141 // Stack allocate the DirtyCardToOopClosure instance
142 HeapRegionDCTOC cl(_g1h, r, _oc,
143 CardTableModRefBS::Precise);
144
145 // Set the "from" region in the closure.
146 _oc->set_region(r);
147 MemRegion card_region(_bot_shared->address_for_index(index), G1BlockOffsetSharedArray::N_words);
148 MemRegion pre_gc_allocated(r->bottom(), r->scan_top());
149 MemRegion mr = pre_gc_allocated.intersection(card_region);
150 if (!mr.is_empty() && !_ct_bs->is_card_claimed(index)) {
151 // We make the card as "claimed" lazily (so races are possible
152 // but they're benign), which reduces the number of duplicate
153 // scans (the rsets of the regions in the cset can intersect).
154 _ct_bs->set_card_claimed(index);
155 _cards_done++;
156 cl.do_MemRegion(mr);
157 }
158 }
159
160 void printCard(HeapRegion* card_region, size_t card_index,
161 HeapWord* card_start) {
162 gclog_or_tty->print_cr("T " UINT32_FORMAT " Region [" PTR_FORMAT ", " PTR_FORMAT ") "
163 "RS names card %p: "
164 "[" PTR_FORMAT ", " PTR_FORMAT ")",
165 _worker_i,
166 card_region->bottom(), card_region->end(),
167 card_index,
168 card_start, card_start + G1BlockOffsetSharedArray::N_words);
169 }
170
171 void scan_strong_code_roots(HeapRegion* r) {
172 double scan_start = os::elapsedTime();
173 r->strong_code_roots_do(_code_root_cl);
174 _strong_code_root_scan_time_sec += (os::elapsedTime() - scan_start);
175 }
176
177 bool doHeapRegion(HeapRegion* r) {
178 assert(r->in_collection_set(), "should only be called on elements of CS.");
179 HeapRegionRemSet* hrrs = r->rem_set();
180 if (hrrs->iter_is_complete()) return false; // All done.
181 if (!_try_claimed && !hrrs->claim_iter()) return false;
182 // If we ever free the collection set concurrently, we should also
183 // clear the card table concurrently therefore we won't need to
184 // add regions of the collection set to the dirty cards region.
185 _g1h->push_dirty_cards_region(r);
186 // If we didn't return above, then
187 // _try_claimed || r->claim_iter()
188 // is true: either we're supposed to work on claimed-but-not-complete
189 // regions, or we successfully claimed the region.
190
191 HeapRegionRemSetIterator iter(hrrs);
192 size_t card_index;
193
194 // We claim cards in block so as to recude the contention. The block size is determined by
195 // the G1RSetScanBlockSize parameter.
196 size_t jump_to_card = hrrs->iter_claimed_next(_block_size);
197 for (size_t current_card = 0; iter.has_next(card_index); current_card++) {
198 if (current_card >= jump_to_card + _block_size) {
199 jump_to_card = hrrs->iter_claimed_next(_block_size);
200 }
201 if (current_card < jump_to_card) continue;
202 HeapWord* card_start = _g1h->bot_shared()->address_for_index(card_index);
203 #if 0
204 gclog_or_tty->print("Rem set iteration yielded card [" PTR_FORMAT ", " PTR_FORMAT ").\n",
205 card_start, card_start + CardTableModRefBS::card_size_in_words);
206 #endif
207
208 HeapRegion* card_region = _g1h->heap_region_containing(card_start);
209 _cards++;
210
211 if (!card_region->is_on_dirty_cards_region_list()) {
212 _g1h->push_dirty_cards_region(card_region);
213 }
214
215 // If the card is dirty, then we will scan it during updateRS.
216 if (!card_region->in_collection_set() &&
217 !_ct_bs->is_card_dirty(card_index)) {
218 scanCard(card_index, card_region);
219 }
220 }
221 if (!_try_claimed) {
222 // Scan the strong code root list attached to the current region
223 scan_strong_code_roots(r);
224
225 hrrs->set_iter_complete();
226 }
227 return false;
228 }
229
230 double strong_code_root_scan_time_sec() {
231 return _strong_code_root_scan_time_sec;
232 }
233
234 size_t cards_done() { return _cards_done;}
235 size_t cards_looked_up() { return _cards;}
236 };
237
238 void G1RemSet::scanRS(G1ParPushHeapRSClosure* oc,
239 CodeBlobClosure* code_root_cl,
240 uint worker_i) {
241 double rs_time_start = os::elapsedTime();
242 HeapRegion *startRegion = _g1->start_cset_region_for_worker(worker_i);
243
244 ScanRSClosure scanRScl(oc, code_root_cl, worker_i);
245
246 _g1->collection_set_iterate_from(startRegion, &scanRScl);
247 scanRScl.set_try_claimed();
248 _g1->collection_set_iterate_from(startRegion, &scanRScl);
249
250 double scan_rs_time_sec = (os::elapsedTime() - rs_time_start)
251 - scanRScl.strong_code_root_scan_time_sec();
252
253 assert(_cards_scanned != NULL, "invariant");
254 _cards_scanned[worker_i] = scanRScl.cards_done();
255
256 _g1p->phase_times()->record_time_secs(G1GCPhaseTimes::ScanRS, worker_i, scan_rs_time_sec);
257 _g1p->phase_times()->record_time_secs(G1GCPhaseTimes::CodeRoots, worker_i, scanRScl.strong_code_root_scan_time_sec());
258 }
259
260 // Closure used for updating RSets and recording references that
261 // point into the collection set. Only called during an
262 // evacuation pause.
263
264 class RefineRecordRefsIntoCSCardTableEntryClosure: public CardTableEntryClosure {
265 G1RemSet* _g1rs;
266 DirtyCardQueue* _into_cset_dcq;
267 public:
268 RefineRecordRefsIntoCSCardTableEntryClosure(G1CollectedHeap* g1h,
269 DirtyCardQueue* into_cset_dcq) :
270 _g1rs(g1h->g1_rem_set()), _into_cset_dcq(into_cset_dcq)
271 {}
272 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
273 // The only time we care about recording cards that
274 // contain references that point into the collection set
275 // is during RSet updating within an evacuation pause.
276 // In this case worker_i should be the id of a GC worker thread.
277 assert(SafepointSynchronize::is_at_safepoint(), "not during an evacuation pause");
278 assert(worker_i < (ParallelGCThreads == 0 ? 1 : ParallelGCThreads), "should be a GC worker");
279
280 if (_g1rs->refine_card(card_ptr, worker_i, true)) {
281 // 'card_ptr' contains references that point into the collection
282 // set. We need to record the card in the DCQS
283 // (G1CollectedHeap::into_cset_dirty_card_queue_set())
284 // that's used for that purpose.
285 //
286 // Enqueue the card
287 _into_cset_dcq->enqueue(card_ptr);
288 }
289 return true;
290 }
291 };
292
293 void G1RemSet::updateRS(DirtyCardQueue* into_cset_dcq, uint worker_i) {
294 G1GCParPhaseTimesTracker x(_g1p->phase_times(), G1GCPhaseTimes::UpdateRS, worker_i);
295 // Apply the given closure to all remaining log entries.
296 RefineRecordRefsIntoCSCardTableEntryClosure into_cset_update_rs_cl(_g1, into_cset_dcq);
297
298 _g1->iterate_dirty_card_closure(&into_cset_update_rs_cl, into_cset_dcq, false, worker_i);
299 }
300
301 void G1RemSet::cleanupHRRS() {
302 HeapRegionRemSet::cleanup();
303 }
304
305 void G1RemSet::oops_into_collection_set_do(G1ParPushHeapRSClosure* oc,
306 CodeBlobClosure* code_root_cl,
307 uint worker_i) {
308 #if CARD_REPEAT_HISTO
309 ct_freq_update_histo_and_reset();
310 #endif
311
312 // We cache the value of 'oc' closure into the appropriate slot in the
313 // _cset_rs_update_cl for this worker
314 assert(worker_i < n_workers(), "sanity");
315 _cset_rs_update_cl[worker_i] = oc;
316
317 // A DirtyCardQueue that is used to hold cards containing references
318 // that point into the collection set. This DCQ is associated with a
319 // special DirtyCardQueueSet (see g1CollectedHeap.hpp). Under normal
320 // circumstances (i.e. the pause successfully completes), these cards
321 // are just discarded (there's no need to update the RSets of regions
322 // that were in the collection set - after the pause these regions
323 // are wholly 'free' of live objects. In the event of an evacuation
324 // failure the cards/buffers in this queue set are passed to the
325 // DirtyCardQueueSet that is used to manage RSet updates
326 DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set());
327
328 assert((ParallelGCThreads > 0) || worker_i == 0, "invariant");
329
330 updateRS(&into_cset_dcq, worker_i);
331 scanRS(oc, code_root_cl, worker_i);
332
333 // We now clear the cached values of _cset_rs_update_cl for this worker
334 _cset_rs_update_cl[worker_i] = NULL;
335 }
336
337 void G1RemSet::prepare_for_oops_into_collection_set_do() {
338 _g1->set_refine_cte_cl_concurrency(false);
339 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
340 dcqs.concatenate_logs();
341
342 guarantee( _cards_scanned == NULL, "invariant" );
343 _cards_scanned = NEW_C_HEAP_ARRAY(size_t, n_workers(), mtGC);
344 for (uint i = 0; i < n_workers(); ++i) {
345 _cards_scanned[i] = 0;
346 }
347 _total_cards_scanned = 0;
348 }
349
350 void G1RemSet::cleanup_after_oops_into_collection_set_do() {
351 guarantee( _cards_scanned != NULL, "invariant" );
352 _total_cards_scanned = 0;
353 for (uint i = 0; i < n_workers(); ++i) {
354 _total_cards_scanned += _cards_scanned[i];
355 }
356 FREE_C_HEAP_ARRAY(size_t, _cards_scanned, mtGC);
357 _cards_scanned = NULL;
358 // Cleanup after copy
359 _g1->set_refine_cte_cl_concurrency(true);
360 // Set all cards back to clean.
361 _g1->cleanUpCardTable();
362
363 DirtyCardQueueSet& into_cset_dcqs = _g1->into_cset_dirty_card_queue_set();
364 int into_cset_n_buffers = into_cset_dcqs.completed_buffers_num();
365
366 if (_g1->evacuation_failed()) {
367 double restore_remembered_set_start = os::elapsedTime();
368
369 // Restore remembered sets for the regions pointing into the collection set.
370 // We just need to transfer the completed buffers from the DirtyCardQueueSet
371 // used to hold cards that contain references that point into the collection set
372 // to the DCQS used to hold the deferred RS updates.
373 _g1->dirty_card_queue_set().merge_bufferlists(&into_cset_dcqs);
374 _g1->g1_policy()->phase_times()->record_evac_fail_restore_remsets((os::elapsedTime() - restore_remembered_set_start) * 1000.0);
375 }
376
377 // Free any completed buffers in the DirtyCardQueueSet used to hold cards
378 // which contain references that point into the collection.
379 _g1->into_cset_dirty_card_queue_set().clear();
380 assert(_g1->into_cset_dirty_card_queue_set().completed_buffers_num() == 0,
381 "all buffers should be freed");
382 _g1->into_cset_dirty_card_queue_set().clear_n_completed_buffers();
383 }
384
385 class ScrubRSClosure: public HeapRegionClosure {
386 G1CollectedHeap* _g1h;
387 BitMap* _region_bm;
388 BitMap* _card_bm;
389 CardTableModRefBS* _ctbs;
390 public:
391 ScrubRSClosure(BitMap* region_bm, BitMap* card_bm) :
392 _g1h(G1CollectedHeap::heap()),
393 _region_bm(region_bm), _card_bm(card_bm),
394 _ctbs(_g1h->g1_barrier_set()) {}
395
396 bool doHeapRegion(HeapRegion* r) {
397 if (!r->continuesHumongous()) {
398 r->rem_set()->scrub(_ctbs, _region_bm, _card_bm);
399 }
400 return false;
401 }
402 };
403
404 void G1RemSet::scrub(BitMap* region_bm, BitMap* card_bm) {
405 ScrubRSClosure scrub_cl(region_bm, card_bm);
406 _g1->heap_region_iterate(&scrub_cl);
407 }
408
409 void G1RemSet::scrub_par(BitMap* region_bm, BitMap* card_bm,
410 uint worker_num, int claim_val) {
411 ScrubRSClosure scrub_cl(region_bm, card_bm);
412 _g1->heap_region_par_iterate_chunked(&scrub_cl,
413 worker_num,
414 n_workers(),
415 claim_val);
416 }
417
418 G1TriggerClosure::G1TriggerClosure() :
419 _triggered(false) { }
420
421 G1InvokeIfNotTriggeredClosure::G1InvokeIfNotTriggeredClosure(G1TriggerClosure* t_cl,
422 OopClosure* oop_cl) :
423 _trigger_cl(t_cl), _oop_cl(oop_cl) { }
424
425 G1Mux2Closure::G1Mux2Closure(OopClosure *c1, OopClosure *c2) :
426 _c1(c1), _c2(c2) { }
427
428 G1UpdateRSOrPushRefOopClosure::
429 G1UpdateRSOrPushRefOopClosure(G1CollectedHeap* g1h,
430 G1RemSet* rs,
431 G1ParPushHeapRSClosure* push_ref_cl,
432 bool record_refs_into_cset,
433 uint worker_i) :
434 _g1(g1h), _g1_rem_set(rs), _from(NULL),
435 _record_refs_into_cset(record_refs_into_cset),
436 _push_ref_cl(push_ref_cl), _worker_i(worker_i) { }
437
438 // Returns true if the given card contains references that point
439 // into the collection set, if we're checking for such references;
440 // false otherwise.
441
442 bool G1RemSet::refine_card(jbyte* card_ptr, uint worker_i,
443 bool check_for_refs_into_cset) {
444 assert(_g1->is_in_exact(_ct_bs->addr_for(card_ptr)),
445 err_msg("Card at " PTR_FORMAT " index " SIZE_FORMAT " representing heap at " PTR_FORMAT " (%u) must be in committed heap",
446 p2i(card_ptr),
447 _ct_bs->index_for(_ct_bs->addr_for(card_ptr)),
448 _ct_bs->addr_for(card_ptr),
449 _g1->addr_to_region(_ct_bs->addr_for(card_ptr))));
450
451 // If the card is no longer dirty, nothing to do.
452 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
453 // No need to return that this card contains refs that point
454 // into the collection set.
455 return false;
456 }
457
458 // Construct the region representing the card.
459 HeapWord* start = _ct_bs->addr_for(card_ptr);
460 // And find the region containing it.
461 HeapRegion* r = _g1->heap_region_containing(start);
462
463 // This check is needed for some uncommon cases where we should
464 // ignore the card.
465 //
466 // The region could be young. Cards for young regions are
467 // distinctly marked (set to g1_young_gen), so the post-barrier will
468 // filter them out. However, that marking is performed
469 // concurrently. A write to a young object could occur before the
470 // card has been marked young, slipping past the filter.
471 //
472 // The card could be stale, because the region has been freed since
473 // the card was recorded. In this case the region type could be
474 // anything. If (still) free or (reallocated) young, just ignore
475 // it. If (reallocated) old or humongous, the later card trimming
476 // and additional checks in iteration may detect staleness. At
477 // worst, we end up processing a stale card unnecessarily.
478 //
479 // In the normal (non-stale) case, the synchronization between the
480 // enqueueing of the card and processing it here will have ensured
481 // we see the up-to-date region type here.
482 if (!r->is_old_or_humongous()) {
483 return false;
484 }
485
486 // While we are processing RSet buffers during the collection, we
487 // actually don't want to scan any cards on the collection set,
488 // since we don't want to update remebered sets with entries that
489 // point into the collection set, given that live objects from the
490 // collection set are about to move and such entries will be stale
491 // very soon. This change also deals with a reliability issue which
492 // involves scanning a card in the collection set and coming across
493 // an array that was being chunked and looking malformed. Note,
494 // however, that if evacuation fails, we have to scan any objects
495 // that were not moved and create any missing entries.
496 if (r->in_collection_set()) {
497 return false;
498 }
499
500 // The result from the hot card cache insert call is either:
501 // * pointer to the current card
502 // (implying that the current card is not 'hot'),
503 // * null
504 // (meaning we had inserted the card ptr into the "hot" card cache,
505 // which had some headroom),
506 // * a pointer to a "hot" card that was evicted from the "hot" cache.
507 //
508
509 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
510 if (hot_card_cache->use_cache()) {
511 assert(!check_for_refs_into_cset, "sanity");
512 assert(!SafepointSynchronize::is_at_safepoint(), "sanity");
513
514 const jbyte* orig_card_ptr = card_ptr;
515 card_ptr = hot_card_cache->insert(card_ptr);
516 if (card_ptr == NULL) {
517 // There was no eviction. Nothing to do.
518 return false;
519 } else if (card_ptr != orig_card_ptr) {
520 // Original card was inserted and an old card was evicted.
521 start = _ct_bs->addr_for(card_ptr);
522 r = _g1->heap_region_containing(start);
523
524 // Check whether the region formerly in the cache should be
525 // ignored, as discussed earlier for the original card. The
526 // region could have been freed while in the cache. The cset is
527 // not relevant here, since we're in concurrent phase.
528 if (!r->is_old_or_humongous()) {
529 return false;
530 }
531 } // Else we still have the original card.
532 }
533
534 // Trim the region designated by the card to what's been allocated
535 // in the region. The card could be stale, or the card could cover
536 // (part of) an object at the end of the allocated space and extend
537 // beyond the end of allocation.
538 HeapWord* scan_limit;
539 if (_g1->is_gc_active()) {
540 // If we're in a STW GC, then a card might be in a GC alloc region
541 // and extend onto a GC LAB, which may not be parsable. Stop such
542 // at the "scan_top" of the region.
543 scan_limit = r->scan_top();
544 } else {
545 // Non-humongous objects are only allocated in the old-gen during
546 // GC, so if region is old then top is stable. Humongous object
547 // allocation sets top last; if top has not yet been set, this is
548 // a stale card and we'll end up with an empty intersection. If
549 // this is not a stale card, the synchronization between the
550 // enqueuing of the card and processing it here will have ensured
551 // we see the up-to-date top here.
552 scan_limit = r->top();
553 }
554 if (scan_limit <= start) {
555 // If the trimmed region is empty, the card must be stale.
556 return false;
557 }
558
559 // Okay to clean and process the card now. There are still some
560 // stale card cases that may be detected by iteration and dealt with
561 // as iteration failure.
562 *const_cast<volatile jbyte*>(card_ptr) = CardTableModRefBS::clean_card_val();
563
564 // This fence serves two purposes. First, the card must be cleaned
565 // before processing the contents. Second, we can't proceed with
566 // processing until after the read of top, for synchronization with
567 // possibly concurrent humongous object allocation. It's okay that
568 // reading top and reading type were racy wrto each other. We need
569 // both set, in any order, to proceed.
570 OrderAccess::fence();
571
572 // Don't use addr_for(card_ptr + 1) which can ask for
573 // a card beyond the heap.
574 HeapWord* end = start + CardTableModRefBS::card_size_in_words;
575 MemRegion dirty_region(start, MIN2(scan_limit, end));
576 assert(!dirty_region.is_empty(), "sanity");
577
578 #if CARD_REPEAT_HISTO
579 init_ct_freq_table(_g1->max_capacity());
580 ct_freq_note_card(_ct_bs->index_for(start));
581 #endif
582
583 G1ParPushHeapRSClosure* oops_in_heap_closure = NULL;
584 if (check_for_refs_into_cset) {
585 // ConcurrentG1RefineThreads have worker numbers larger than what
586 // _cset_rs_update_cl[] is set up to handle. But those threads should
587 // only be active outside of a collection which means that when they
588 // reach here they should have check_for_refs_into_cset == false.
589 assert((size_t)worker_i < n_workers(), "index of worker larger than _cset_rs_update_cl[].length");
590 oops_in_heap_closure = _cset_rs_update_cl[worker_i];
591 }
592 G1UpdateRSOrPushRefOopClosure update_rs_oop_cl(_g1,
593 _g1->g1_rem_set(),
594 oops_in_heap_closure,
595 check_for_refs_into_cset,
596 worker_i);
597 update_rs_oop_cl.set_from(r);
598
599 G1TriggerClosure trigger_cl;
600 FilterIntoCSClosure into_cs_cl(NULL, _g1, &trigger_cl);
601 G1InvokeIfNotTriggeredClosure invoke_cl(&trigger_cl, &into_cs_cl);
602 G1Mux2Closure mux(&invoke_cl, &update_rs_oop_cl);
603
604 FilterOutOfRegionClosure filter_then_update_rs_oop_cl(r,
605 (check_for_refs_into_cset ?
606 (OopClosure*)&mux :
607 (OopClosure*)&update_rs_oop_cl));
608
609 bool card_processed =
610 r->oops_on_card_seq_iterate_careful(dirty_region,
611 &filter_then_update_rs_oop_cl);
612
613 // If unable to process the card then we encountered an unparsable
614 // part of the heap (e.g. a partially allocated object) while
615 // processing a stale card. Despite the card being stale, redirty
616 // and re-enqueue, because we've already cleaned the card. Without
617 // this we could incorrectly discard a non-stale card.
618 if (!card_processed) {
619 assert(!_g1->is_gc_active(), "Unparsable heap during GC");
620 // The card might have gotten re-dirtied and re-enqueued while we
621 // worked. (In fact, it's pretty likely.)
622 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
623 *card_ptr = CardTableModRefBS::dirty_card_val();
624 MutexLockerEx x(Shared_DirtyCardQ_lock,
625 Mutex::_no_safepoint_check_flag);
626 DirtyCardQueue* sdcq =
627 JavaThread::dirty_card_queue_set().shared_dirty_card_queue();
628 sdcq->enqueue(card_ptr);
629 }
630 } else {
631 _conc_refine_cards++;
632 }
633
634 // This gets set to true if the card being refined has
635 // references that point into the collection set.
636 bool has_refs_into_cset = trigger_cl.triggered();
637
638 // We should only be detecting that the card contains references
639 // that point into the collection set if the current thread is
640 // a GC worker thread.
641 assert(!has_refs_into_cset || SafepointSynchronize::is_at_safepoint(),
642 "invalid result at non safepoint");
643
644 return has_refs_into_cset;
645 }
646
647 void G1RemSet::print_periodic_summary_info(const char* header) {
648 G1RemSetSummary current;
649 current.initialize(this);
650
651 _prev_period_summary.subtract_from(¤t);
652 print_summary_info(&_prev_period_summary, header);
653
654 _prev_period_summary.set(¤t);
655 }
656
657 void G1RemSet::print_summary_info() {
658 G1RemSetSummary current;
659 current.initialize(this);
660
661 print_summary_info(¤t, " Cumulative RS summary");
662 }
663
664 void G1RemSet::print_summary_info(G1RemSetSummary * summary, const char * header) {
665 assert(summary != NULL, "just checking");
666
667 if (header != NULL) {
668 gclog_or_tty->print_cr("%s", header);
669 }
670
671 #if CARD_REPEAT_HISTO
672 gclog_or_tty->print_cr("\nG1 card_repeat count histogram: ");
673 gclog_or_tty->print_cr(" # of repeats --> # of cards with that number.");
674 card_repeat_count.print_on(gclog_or_tty);
675 #endif
676
677 summary->print_on(gclog_or_tty);
678 }
679
680 void G1RemSet::prepare_for_verify() {
681 if (G1HRRSFlushLogBuffersOnVerify &&
682 (VerifyBeforeGC || VerifyAfterGC)
683 && (!_g1->full_collection() || G1VerifyRSetsDuringFullGC)) {
684 cleanupHRRS();
685 _g1->set_refine_cte_cl_concurrency(false);
686 if (SafepointSynchronize::is_at_safepoint()) {
687 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
688 dcqs.concatenate_logs();
689 }
690
691 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
692 bool use_hot_card_cache = hot_card_cache->use_cache();
693 hot_card_cache->set_use_cache(false);
694
695 DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set());
696 updateRS(&into_cset_dcq, 0);
697 _g1->into_cset_dirty_card_queue_set().clear();
698
699 hot_card_cache->set_use_cache(use_hot_card_cache);
700 assert(JavaThread::dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
701 }
702 }