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