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