1 /*
2 * Copyright (c) 1997, 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/shared/gcTimer.hpp"
27 #include "gc_implementation/shared/gcTrace.hpp"
28 #include "gc_implementation/shared/spaceDecorator.hpp"
29 #include "gc_interface/collectedHeap.inline.hpp"
30 #include "memory/allocation.inline.hpp"
31 #include "memory/blockOffsetTable.inline.hpp"
32 #include "memory/cardTableRS.hpp"
33 #include "memory/gcLocker.inline.hpp"
34 #include "memory/genCollectedHeap.hpp"
35 #include "memory/genMarkSweep.hpp"
36 #include "memory/genOopClosures.hpp"
37 #include "memory/genOopClosures.inline.hpp"
38 #include "memory/generation.hpp"
39 #include "memory/generation.inline.hpp"
40 #include "memory/space.inline.hpp"
41 #include "oops/oop.inline.hpp"
42 #include "runtime/java.hpp"
43 #include "utilities/copy.hpp"
44 #include "utilities/events.hpp"
45
46 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
47
48 Generation::Generation(ReservedSpace rs, size_t initial_size, int level) :
49 _level(level),
50 _ref_processor(NULL) {
51 if (!_virtual_space.initialize(rs, initial_size)) {
52 vm_exit_during_initialization("Could not reserve enough space for "
53 "object heap");
54 }
55 // Mangle all of the the initial generation.
56 if (ZapUnusedHeapArea) {
57 MemRegion mangle_region((HeapWord*)_virtual_space.low(),
58 (HeapWord*)_virtual_space.high());
59 SpaceMangler::mangle_region(mangle_region);
60 }
61 _reserved = MemRegion((HeapWord*)_virtual_space.low_boundary(),
62 (HeapWord*)_virtual_space.high_boundary());
63 }
64
65 GenerationSpec* Generation::spec() {
66 GenCollectedHeap* gch = GenCollectedHeap::heap();
67 assert(0 <= level() && level() < gch->_n_gens, "Bad gen level");
68 return gch->_gen_specs[level()];
69 }
70
71 size_t Generation::max_capacity() const {
72 return reserved().byte_size();
73 }
74
75 void Generation::print_heap_change(size_t prev_used) const {
76 if (PrintGCDetails && Verbose) {
77 gclog_or_tty->print(" " SIZE_FORMAT
78 "->" SIZE_FORMAT
79 "(" SIZE_FORMAT ")",
80 prev_used, used(), capacity());
81 } else {
82 gclog_or_tty->print(" " SIZE_FORMAT "K"
83 "->" SIZE_FORMAT "K"
84 "(" SIZE_FORMAT "K)",
85 prev_used / K, used() / K, capacity() / K);
86 }
87 }
88
89 // By default we get a single threaded default reference processor;
90 // generations needing multi-threaded refs processing or discovery override this method.
91 void Generation::ref_processor_init() {
92 assert(_ref_processor == NULL, "a reference processor already exists");
93 assert(!_reserved.is_empty(), "empty generation?");
94 _ref_processor = new ReferenceProcessor(_reserved); // a vanilla reference processor
95 if (_ref_processor == NULL) {
96 vm_exit_during_initialization("Could not allocate ReferenceProcessor object");
97 }
98 }
99
100 void Generation::print() const { print_on(tty); }
101
102 void Generation::print_on(outputStream* st) const {
103 st->print(" %-20s", name());
104 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
105 capacity()/K, used()/K);
106 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
107 _virtual_space.low_boundary(),
108 _virtual_space.high(),
109 _virtual_space.high_boundary());
110 }
111
112 void Generation::print_summary_info() { print_summary_info_on(tty); }
113
114 void Generation::print_summary_info_on(outputStream* st) {
115 StatRecord* sr = stat_record();
116 double time = sr->accumulated_time.seconds();
117 st->print_cr("[Accumulated GC generation %d time %3.7f secs, "
118 "%d GC's, avg GC time %3.7f]",
119 level(), time, sr->invocations,
120 sr->invocations > 0 ? time / sr->invocations : 0.0);
121 }
122
123 // Utility iterator classes
124
125 class GenerationIsInReservedClosure : public SpaceClosure {
126 public:
127 const void* _p;
128 Space* sp;
129 virtual void do_space(Space* s) {
130 if (sp == NULL) {
131 if (s->is_in_reserved(_p)) sp = s;
132 }
133 }
134 GenerationIsInReservedClosure(const void* p) : _p(p), sp(NULL) {}
135 };
136
137 class GenerationIsInClosure : public SpaceClosure {
138 public:
139 const void* _p;
140 Space* sp;
141 virtual void do_space(Space* s) {
142 if (sp == NULL) {
143 if (s->is_in(_p)) sp = s;
144 }
145 }
146 GenerationIsInClosure(const void* p) : _p(p), sp(NULL) {}
147 };
148
149 bool Generation::is_in(const void* p) const {
150 GenerationIsInClosure blk(p);
151 ((Generation*)this)->space_iterate(&blk);
152 return blk.sp != NULL;
153 }
154
155 DefNewGeneration* Generation::as_DefNewGeneration() {
156 assert((kind() == Generation::DefNew) ||
157 (kind() == Generation::ParNew) ||
158 (kind() == Generation::ASParNew),
159 "Wrong youngest generation type");
160 return (DefNewGeneration*) this;
161 }
162
163 Generation* Generation::next_gen() const {
164 GenCollectedHeap* gch = GenCollectedHeap::heap();
165 int next = level() + 1;
166 if (next < gch->_n_gens) {
167 return gch->_gens[next];
168 } else {
169 return NULL;
170 }
171 }
172
173 size_t Generation::max_contiguous_available() const {
174 // The largest number of contiguous free words in this or any higher generation.
175 size_t max = 0;
176 for (const Generation* gen = this; gen != NULL; gen = gen->next_gen()) {
177 size_t avail = gen->contiguous_available();
178 if (avail > max) {
179 max = avail;
180 }
181 }
182 return max;
183 }
184
185 bool Generation::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const {
186 size_t available = max_contiguous_available();
187 bool res = (available >= max_promotion_in_bytes);
188 if (PrintGC && Verbose) {
189 gclog_or_tty->print_cr(
190 "Generation: promo attempt is%s safe: available("SIZE_FORMAT") %s max_promo("SIZE_FORMAT")",
191 res? "":" not", available, res? ">=":"<",
192 max_promotion_in_bytes);
193 }
194 return res;
195 }
196
197 // Ignores "ref" and calls allocate().
198 oop Generation::promote(oop obj, size_t obj_size) {
199 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
200
201 #ifndef PRODUCT
202 if (Universe::heap()->promotion_should_fail()) {
203 return NULL;
204 }
205 #endif // #ifndef PRODUCT
206
207 HeapWord* result = allocate(obj_size, false);
208 if (result != NULL) {
209 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
210 return oop(result);
211 } else {
212 GenCollectedHeap* gch = GenCollectedHeap::heap();
213 return gch->handle_failed_promotion(this, obj, obj_size);
214 }
215 }
216
217 oop Generation::par_promote(int thread_num,
218 oop obj, markOop m, size_t word_sz) {
219 // Could do a bad general impl here that gets a lock. But no.
220 ShouldNotCallThis();
221 return NULL;
222 }
223
224 void Generation::par_promote_alloc_undo(int thread_num,
225 HeapWord* obj, size_t word_sz) {
226 // Could do a bad general impl here that gets a lock. But no.
227 guarantee(false, "No good general implementation.");
228 }
229
230 Space* Generation::space_containing(const void* p) const {
231 GenerationIsInReservedClosure blk(p);
232 // Cast away const
233 ((Generation*)this)->space_iterate(&blk);
234 return blk.sp;
235 }
236
237 // Some of these are mediocre general implementations. Should be
238 // overridden to get better performance.
239
240 class GenerationBlockStartClosure : public SpaceClosure {
241 public:
242 const void* _p;
243 HeapWord* _start;
244 virtual void do_space(Space* s) {
245 if (_start == NULL && s->is_in_reserved(_p)) {
246 _start = s->block_start(_p);
247 }
248 }
249 GenerationBlockStartClosure(const void* p) { _p = p; _start = NULL; }
250 };
251
252 HeapWord* Generation::block_start(const void* p) const {
253 GenerationBlockStartClosure blk(p);
254 // Cast away const
255 ((Generation*)this)->space_iterate(&blk);
256 return blk._start;
257 }
258
259 class GenerationBlockSizeClosure : public SpaceClosure {
260 public:
261 const HeapWord* _p;
262 size_t size;
263 virtual void do_space(Space* s) {
264 if (size == 0 && s->is_in_reserved(_p)) {
265 size = s->block_size(_p);
266 }
267 }
268 GenerationBlockSizeClosure(const HeapWord* p) { _p = p; size = 0; }
269 };
270
271 size_t Generation::block_size(const HeapWord* p) const {
272 GenerationBlockSizeClosure blk(p);
273 // Cast away const
274 ((Generation*)this)->space_iterate(&blk);
275 assert(blk.size > 0, "seems reasonable");
276 return blk.size;
277 }
278
279 class GenerationBlockIsObjClosure : public SpaceClosure {
280 public:
281 const HeapWord* _p;
282 bool is_obj;
283 virtual void do_space(Space* s) {
284 if (!is_obj && s->is_in_reserved(_p)) {
285 is_obj |= s->block_is_obj(_p);
286 }
287 }
288 GenerationBlockIsObjClosure(const HeapWord* p) { _p = p; is_obj = false; }
289 };
290
291 bool Generation::block_is_obj(const HeapWord* p) const {
292 GenerationBlockIsObjClosure blk(p);
293 // Cast away const
294 ((Generation*)this)->space_iterate(&blk);
295 return blk.is_obj;
296 }
297
298 class GenerationOopIterateClosure : public SpaceClosure {
299 public:
300 ExtendedOopClosure* _cl;
301 virtual void do_space(Space* s) {
302 s->oop_iterate(_cl);
303 }
304 GenerationOopIterateClosure(ExtendedOopClosure* cl) :
305 _cl(cl) {}
306 };
307
308 void Generation::oop_iterate(ExtendedOopClosure* cl) {
309 GenerationOopIterateClosure blk(cl);
310 space_iterate(&blk);
311 }
312
313 void Generation::younger_refs_in_space_iterate(Space* sp,
314 OopsInGenClosure* cl) {
315 GenRemSet* rs = SharedHeap::heap()->rem_set();
316 rs->younger_refs_in_space_iterate(sp, cl);
317 }
318
319 class GenerationObjIterateClosure : public SpaceClosure {
320 private:
321 ObjectClosure* _cl;
322 public:
323 virtual void do_space(Space* s) {
324 s->object_iterate(_cl);
325 }
326 GenerationObjIterateClosure(ObjectClosure* cl) : _cl(cl) {}
327 };
328
329 void Generation::object_iterate(ObjectClosure* cl) {
330 GenerationObjIterateClosure blk(cl);
331 space_iterate(&blk);
332 }
333
334 class GenerationSafeObjIterateClosure : public SpaceClosure {
335 private:
336 ObjectClosure* _cl;
337 public:
338 virtual void do_space(Space* s) {
339 s->safe_object_iterate(_cl);
340 }
341 GenerationSafeObjIterateClosure(ObjectClosure* cl) : _cl(cl) {}
342 };
343
344 void Generation::safe_object_iterate(ObjectClosure* cl) {
345 GenerationSafeObjIterateClosure blk(cl);
346 space_iterate(&blk);
347 }
348
349 void Generation::prepare_for_compaction(CompactPoint* cp) {
350 // Generic implementation, can be specialized
351 CompactibleSpace* space = first_compaction_space();
352 while (space != NULL) {
353 space->prepare_for_compaction(cp);
354 space = space->next_compaction_space();
355 }
356 }
357
358 class AdjustPointersClosure: public SpaceClosure {
359 public:
360 void do_space(Space* sp) {
361 sp->adjust_pointers();
362 }
363 };
364
365 void Generation::adjust_pointers() {
366 // Note that this is done over all spaces, not just the compactible
367 // ones.
368 AdjustPointersClosure blk;
369 space_iterate(&blk, true);
370 }
371
372 void Generation::compact() {
373 CompactibleSpace* sp = first_compaction_space();
374 while (sp != NULL) {
375 sp->compact();
376 sp = sp->next_compaction_space();
377 }
378 }
379
380 CardGeneration::CardGeneration(ReservedSpace rs, size_t initial_byte_size,
381 int level,
382 GenRemSet* remset) :
383 Generation(rs, initial_byte_size, level), _rs(remset),
384 _shrink_factor(0), _min_heap_delta_bytes(), _capacity_at_prologue(),
385 _used_at_prologue()
386 {
387 HeapWord* start = (HeapWord*)rs.base();
388 size_t reserved_byte_size = rs.size();
389 assert((uintptr_t(start) & 3) == 0, "bad alignment");
390 assert((reserved_byte_size & 3) == 0, "bad alignment");
391 MemRegion reserved_mr(start, heap_word_size(reserved_byte_size));
392 _bts = new BlockOffsetSharedArray(reserved_mr,
393 heap_word_size(initial_byte_size));
394 MemRegion committed_mr(start, heap_word_size(initial_byte_size));
395 _rs->resize_covered_region(committed_mr);
396 if (_bts == NULL)
397 vm_exit_during_initialization("Could not allocate a BlockOffsetArray");
398
399 // Verify that the start and end of this generation is the start of a card.
400 // If this wasn't true, a single card could span more than on generation,
401 // which would cause problems when we commit/uncommit memory, and when we
402 // clear and dirty cards.
403 guarantee(_rs->is_aligned(reserved_mr.start()), "generation must be card aligned");
404 if (reserved_mr.end() != Universe::heap()->reserved_region().end()) {
405 // Don't check at the very end of the heap as we'll assert that we're probing off
406 // the end if we try.
407 guarantee(_rs->is_aligned(reserved_mr.end()), "generation must be card aligned");
408 }
409 _min_heap_delta_bytes = MinHeapDeltaBytes;
410 _capacity_at_prologue = initial_byte_size;
411 _used_at_prologue = 0;
412 }
413
414 bool CardGeneration::expand(size_t bytes, size_t expand_bytes) {
415 assert_locked_or_safepoint(Heap_lock);
416 if (bytes == 0) {
417 return true; // That's what grow_by(0) would return
418 }
419 size_t aligned_bytes = ReservedSpace::page_align_size_up(bytes);
420 if (aligned_bytes == 0){
421 // The alignment caused the number of bytes to wrap. An expand_by(0) will
422 // return true with the implication that an expansion was done when it
423 // was not. A call to expand implies a best effort to expand by "bytes"
424 // but not a guarantee. Align down to give a best effort. This is likely
425 // the most that the generation can expand since it has some capacity to
426 // start with.
427 aligned_bytes = ReservedSpace::page_align_size_down(bytes);
428 }
429 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
430 bool success = false;
431 if (aligned_expand_bytes > aligned_bytes) {
432 success = grow_by(aligned_expand_bytes);
433 }
434 if (!success) {
435 success = grow_by(aligned_bytes);
436 }
437 if (!success) {
438 success = grow_to_reserved();
439 }
440 if (PrintGC && Verbose) {
441 if (success && GC_locker::is_active_and_needs_gc()) {
442 gclog_or_tty->print_cr("Garbage collection disabled, expanded heap instead");
443 }
444 }
445
446 return success;
447 }
448
449
450 // No young generation references, clear this generation's cards.
451 void CardGeneration::clear_remembered_set() {
452 _rs->clear(reserved());
453 }
454
455
456 // Objects in this generation may have moved, invalidate this
457 // generation's cards.
458 void CardGeneration::invalidate_remembered_set() {
459 _rs->invalidate(used_region());
460 }
461
462
463 void CardGeneration::compute_new_size() {
464 assert(_shrink_factor <= 100, "invalid shrink factor");
465 size_t current_shrink_factor = _shrink_factor;
466 _shrink_factor = 0;
467
468 // We don't have floating point command-line arguments
469 // Note: argument processing ensures that MinHeapFreeRatio < 100.
470 const double minimum_free_percentage = MinHeapFreeRatio / 100.0;
471 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
472
473 // Compute some numbers about the state of the heap.
474 const size_t used_after_gc = used();
475 const size_t capacity_after_gc = capacity();
476
477 const double min_tmp = used_after_gc / maximum_used_percentage;
478 size_t minimum_desired_capacity = (size_t)MIN2(min_tmp, double(max_uintx));
479 // Don't shrink less than the initial generation size
480 minimum_desired_capacity = MAX2(minimum_desired_capacity,
481 spec()->init_size());
482 assert(used_after_gc <= minimum_desired_capacity, "sanity check");
483
484 if (PrintGC && Verbose) {
485 const size_t free_after_gc = free();
486 const double free_percentage = ((double)free_after_gc) / capacity_after_gc;
487 gclog_or_tty->print_cr("TenuredGeneration::compute_new_size: ");
488 gclog_or_tty->print_cr(" "
489 " minimum_free_percentage: %6.2f"
490 " maximum_used_percentage: %6.2f",
491 minimum_free_percentage,
492 maximum_used_percentage);
493 gclog_or_tty->print_cr(" "
494 " free_after_gc : %6.1fK"
495 " used_after_gc : %6.1fK"
496 " capacity_after_gc : %6.1fK",
497 free_after_gc / (double) K,
498 used_after_gc / (double) K,
499 capacity_after_gc / (double) K);
500 gclog_or_tty->print_cr(" "
501 " free_percentage: %6.2f",
502 free_percentage);
503 }
504
505 if (capacity_after_gc < minimum_desired_capacity) {
506 // If we have less free space than we want then expand
507 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
508 // Don't expand unless it's significant
509 if (expand_bytes >= _min_heap_delta_bytes) {
510 expand(expand_bytes, 0); // safe if expansion fails
511 }
512 if (PrintGC && Verbose) {
513 gclog_or_tty->print_cr(" expanding:"
514 " minimum_desired_capacity: %6.1fK"
515 " expand_bytes: %6.1fK"
516 " _min_heap_delta_bytes: %6.1fK",
517 minimum_desired_capacity / (double) K,
518 expand_bytes / (double) K,
519 _min_heap_delta_bytes / (double) K);
520 }
521 return;
522 }
523
524 // No expansion, now see if we want to shrink
525 size_t shrink_bytes = 0;
526 // We would never want to shrink more than this
527 size_t max_shrink_bytes = capacity_after_gc - minimum_desired_capacity;
528
529 if (MaxHeapFreeRatio < 100) {
530 const double maximum_free_percentage = MaxHeapFreeRatio / 100.0;
531 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
532 const double max_tmp = used_after_gc / minimum_used_percentage;
533 size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(max_uintx));
534 maximum_desired_capacity = MAX2(maximum_desired_capacity,
535 spec()->init_size());
536 if (PrintGC && Verbose) {
537 gclog_or_tty->print_cr(" "
538 " maximum_free_percentage: %6.2f"
539 " minimum_used_percentage: %6.2f",
540 maximum_free_percentage,
541 minimum_used_percentage);
542 gclog_or_tty->print_cr(" "
543 " _capacity_at_prologue: %6.1fK"
544 " minimum_desired_capacity: %6.1fK"
545 " maximum_desired_capacity: %6.1fK",
546 _capacity_at_prologue / (double) K,
547 minimum_desired_capacity / (double) K,
548 maximum_desired_capacity / (double) K);
549 }
550 assert(minimum_desired_capacity <= maximum_desired_capacity,
551 "sanity check");
552
553 if (capacity_after_gc > maximum_desired_capacity) {
554 // Capacity too large, compute shrinking size
555 shrink_bytes = capacity_after_gc - maximum_desired_capacity;
556 // We don't want shrink all the way back to initSize if people call
557 // System.gc(), because some programs do that between "phases" and then
558 // we'd just have to grow the heap up again for the next phase. So we
559 // damp the shrinking: 0% on the first call, 10% on the second call, 40%
560 // on the third call, and 100% by the fourth call. But if we recompute
561 // size without shrinking, it goes back to 0%.
562 shrink_bytes = shrink_bytes / 100 * current_shrink_factor;
563 assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size");
564 if (current_shrink_factor == 0) {
565 _shrink_factor = 10;
566 } else {
567 _shrink_factor = MIN2(current_shrink_factor * 4, (size_t) 100);
568 }
569 if (PrintGC && Verbose) {
570 gclog_or_tty->print_cr(" "
571 " shrinking:"
572 " initSize: %.1fK"
573 " maximum_desired_capacity: %.1fK",
574 spec()->init_size() / (double) K,
575 maximum_desired_capacity / (double) K);
576 gclog_or_tty->print_cr(" "
577 " shrink_bytes: %.1fK"
578 " current_shrink_factor: %d"
579 " new shrink factor: %d"
580 " _min_heap_delta_bytes: %.1fK",
581 shrink_bytes / (double) K,
582 current_shrink_factor,
583 _shrink_factor,
584 _min_heap_delta_bytes / (double) K);
585 }
586 }
587 }
588
589 if (capacity_after_gc > _capacity_at_prologue) {
590 // We might have expanded for promotions, in which case we might want to
591 // take back that expansion if there's room after GC. That keeps us from
592 // stretching the heap with promotions when there's plenty of room.
593 size_t expansion_for_promotion = capacity_after_gc - _capacity_at_prologue;
594 expansion_for_promotion = MIN2(expansion_for_promotion, max_shrink_bytes);
595 // We have two shrinking computations, take the largest
596 shrink_bytes = MAX2(shrink_bytes, expansion_for_promotion);
597 assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size");
598 if (PrintGC && Verbose) {
599 gclog_or_tty->print_cr(" "
600 " aggressive shrinking:"
601 " _capacity_at_prologue: %.1fK"
602 " capacity_after_gc: %.1fK"
603 " expansion_for_promotion: %.1fK"
604 " shrink_bytes: %.1fK",
605 capacity_after_gc / (double) K,
606 _capacity_at_prologue / (double) K,
607 expansion_for_promotion / (double) K,
608 shrink_bytes / (double) K);
609 }
610 }
611 // Don't shrink unless it's significant
612 if (shrink_bytes >= _min_heap_delta_bytes) {
613 shrink(shrink_bytes);
614 }
615 }
616
617 // Currently nothing to do.
618 void CardGeneration::prepare_for_verify() {}
619
620
621 void OneContigSpaceCardGeneration::collect(bool full,
622 bool clear_all_soft_refs,
623 size_t size,
624 bool is_tlab) {
625 GenCollectedHeap* gch = GenCollectedHeap::heap();
626
627 SpecializationStats::clear();
628 // Temporarily expand the span of our ref processor, so
629 // refs discovery is over the entire heap, not just this generation
630 ReferenceProcessorSpanMutator
631 x(ref_processor(), gch->reserved_region());
632
633 STWGCTimer* gc_timer = GenMarkSweep::gc_timer();
634 gc_timer->register_gc_start();
635
636 SerialOldTracer* gc_tracer = GenMarkSweep::gc_tracer();
637 gc_tracer->report_gc_start(gch->gc_cause(), gc_timer->gc_start());
638
639 GenMarkSweep::invoke_at_safepoint(_level, ref_processor(), clear_all_soft_refs);
640
641 gc_timer->register_gc_end();
642
643 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
644
645 SpecializationStats::print();
646 }
647
648 HeapWord*
649 OneContigSpaceCardGeneration::expand_and_allocate(size_t word_size,
650 bool is_tlab,
651 bool parallel) {
652 assert(!is_tlab, "OneContigSpaceCardGeneration does not support TLAB allocation");
653 if (parallel) {
654 MutexLocker x(ParGCRareEvent_lock);
655 HeapWord* result = NULL;
656 size_t byte_size = word_size * HeapWordSize;
657 while (true) {
658 expand(byte_size, _min_heap_delta_bytes);
659 if (GCExpandToAllocateDelayMillis > 0) {
660 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false);
661 }
662 result = _the_space->par_allocate(word_size);
663 if ( result != NULL) {
664 return result;
665 } else {
666 // If there's not enough expansion space available, give up.
667 if (_virtual_space.uncommitted_size() < byte_size) {
668 return NULL;
669 }
670 // else try again
671 }
672 }
673 } else {
674 expand(word_size*HeapWordSize, _min_heap_delta_bytes);
675 return _the_space->allocate(word_size);
676 }
677 }
678
679 bool OneContigSpaceCardGeneration::expand(size_t bytes, size_t expand_bytes) {
680 GCMutexLocker x(ExpandHeap_lock);
681 return CardGeneration::expand(bytes, expand_bytes);
682 }
683
684
685 void OneContigSpaceCardGeneration::shrink(size_t bytes) {
686 assert_locked_or_safepoint(ExpandHeap_lock);
687 size_t size = ReservedSpace::page_align_size_down(bytes);
688 if (size > 0) {
689 shrink_by(size);
690 }
691 }
692
693
694 size_t OneContigSpaceCardGeneration::capacity() const {
695 return _the_space->capacity();
696 }
697
698
699 size_t OneContigSpaceCardGeneration::used() const {
700 return _the_space->used();
701 }
702
703
704 size_t OneContigSpaceCardGeneration::free() const {
705 return _the_space->free();
706 }
707
708 MemRegion OneContigSpaceCardGeneration::used_region() const {
709 return the_space()->used_region();
710 }
711
712 size_t OneContigSpaceCardGeneration::unsafe_max_alloc_nogc() const {
713 return _the_space->free();
714 }
715
716 size_t OneContigSpaceCardGeneration::contiguous_available() const {
717 return _the_space->free() + _virtual_space.uncommitted_size();
718 }
719
720 bool OneContigSpaceCardGeneration::grow_by(size_t bytes) {
721 assert_locked_or_safepoint(ExpandHeap_lock);
722 bool result = _virtual_space.expand_by(bytes);
723 if (result) {
724 size_t new_word_size =
725 heap_word_size(_virtual_space.committed_size());
726 MemRegion mr(_the_space->bottom(), new_word_size);
727 // Expand card table
728 Universe::heap()->barrier_set()->resize_covered_region(mr);
729 // Expand shared block offset array
730 _bts->resize(new_word_size);
731
732 // Fix for bug #4668531
733 if (ZapUnusedHeapArea) {
734 MemRegion mangle_region(_the_space->end(),
735 (HeapWord*)_virtual_space.high());
736 SpaceMangler::mangle_region(mangle_region);
737 }
738
739 // Expand space -- also expands space's BOT
740 // (which uses (part of) shared array above)
741 _the_space->set_end((HeapWord*)_virtual_space.high());
742
743 // update the space and generation capacity counters
744 update_counters();
745
746 if (Verbose && PrintGC) {
747 size_t new_mem_size = _virtual_space.committed_size();
748 size_t old_mem_size = new_mem_size - bytes;
749 gclog_or_tty->print_cr("Expanding %s from " SIZE_FORMAT "K by "
750 SIZE_FORMAT "K to " SIZE_FORMAT "K",
751 name(), old_mem_size/K, bytes/K, new_mem_size/K);
752 }
753 }
754 return result;
755 }
756
757
758 bool OneContigSpaceCardGeneration::grow_to_reserved() {
759 assert_locked_or_safepoint(ExpandHeap_lock);
760 bool success = true;
761 const size_t remaining_bytes = _virtual_space.uncommitted_size();
762 if (remaining_bytes > 0) {
763 success = grow_by(remaining_bytes);
764 DEBUG_ONLY(if (!success) warning("grow to reserved failed");)
765 }
766 return success;
767 }
768
769 void OneContigSpaceCardGeneration::shrink_by(size_t bytes) {
770 assert_locked_or_safepoint(ExpandHeap_lock);
771 // Shrink committed space
772 _virtual_space.shrink_by(bytes);
773 // Shrink space; this also shrinks the space's BOT
774 _the_space->set_end((HeapWord*) _virtual_space.high());
775 size_t new_word_size = heap_word_size(_the_space->capacity());
776 // Shrink the shared block offset array
777 _bts->resize(new_word_size);
778 MemRegion mr(_the_space->bottom(), new_word_size);
779 // Shrink the card table
780 Universe::heap()->barrier_set()->resize_covered_region(mr);
781
782 if (Verbose && PrintGC) {
783 size_t new_mem_size = _virtual_space.committed_size();
784 size_t old_mem_size = new_mem_size + bytes;
785 gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K to " SIZE_FORMAT "K",
786 name(), old_mem_size/K, new_mem_size/K);
787 }
788 }
789
790 // Currently nothing to do.
791 void OneContigSpaceCardGeneration::prepare_for_verify() {}
792
793
794 // Override for a card-table generation with one contiguous
795 // space. NOTE: For reasons that are lost in the fog of history,
796 // this code is used when you iterate over perm gen objects,
797 // even when one uses CDS, where the perm gen has a couple of
798 // other spaces; this is because CompactingPermGenGen derives
799 // from OneContigSpaceCardGeneration. This should be cleaned up,
800 // see CR 6897789..
801 void OneContigSpaceCardGeneration::object_iterate(ObjectClosure* blk) {
802 _the_space->object_iterate(blk);
803 }
804
805 void OneContigSpaceCardGeneration::space_iterate(SpaceClosure* blk,
806 bool usedOnly) {
807 blk->do_space(_the_space);
808 }
809
810 void OneContigSpaceCardGeneration::younger_refs_iterate(OopsInGenClosure* blk) {
811 blk->set_generation(this);
812 younger_refs_in_space_iterate(_the_space, blk);
813 blk->reset_generation();
814 }
815
816 void OneContigSpaceCardGeneration::save_marks() {
817 _the_space->set_saved_mark();
818 }
819
820
821 void OneContigSpaceCardGeneration::reset_saved_marks() {
822 _the_space->reset_saved_mark();
823 }
824
825
826 bool OneContigSpaceCardGeneration::no_allocs_since_save_marks() {
827 return _the_space->saved_mark_at_top();
828 }
829
830 #define OneContig_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
831 \
832 void OneContigSpaceCardGeneration:: \
833 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \
834 blk->set_generation(this); \
835 _the_space->oop_since_save_marks_iterate##nv_suffix(blk); \
836 blk->reset_generation(); \
837 save_marks(); \
838 }
839
840 ALL_SINCE_SAVE_MARKS_CLOSURES(OneContig_SINCE_SAVE_MARKS_ITERATE_DEFN)
841
842 #undef OneContig_SINCE_SAVE_MARKS_ITERATE_DEFN
843
844
845 void OneContigSpaceCardGeneration::gc_epilogue(bool full) {
846 _last_gc = WaterMark(the_space(), the_space()->top());
847
848 // update the generation and space performance counters
849 update_counters();
850 if (ZapUnusedHeapArea) {
851 the_space()->check_mangled_unused_area_complete();
852 }
853 }
854
855 void OneContigSpaceCardGeneration::record_spaces_top() {
856 assert(ZapUnusedHeapArea, "Not mangling unused space");
857 the_space()->set_top_for_allocations();
858 }
859
860 void OneContigSpaceCardGeneration::verify() {
861 the_space()->verify();
862 }
863
864 void OneContigSpaceCardGeneration::print_on(outputStream* st) const {
865 Generation::print_on(st);
866 st->print(" the");
867 the_space()->print_on(st);
868 }