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