1 /*
2 * Copyright (c) 2013, 2020, Red Hat, Inc. 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/shared/space.inline.hpp"
27 #include "gc/shared/tlab_globals.hpp"
28 #include "gc/shenandoah/shenandoahCardTable.hpp"
29 #include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp"
30 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
31 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
32 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
33 #include "gc/shenandoah/shenandoahOldGeneration.hpp"
34 #include "gc/shenandoah/shenandoahGeneration.hpp"
35 #include "gc/shenandoah/shenandoahYoungGeneration.hpp"
36 #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp"
37 #include "jfr/jfrEvents.hpp"
38 #include "memory/allocation.hpp"
39 #include "memory/iterator.inline.hpp"
40 #include "memory/resourceArea.hpp"
41 #include "memory/universe.hpp"
42 #include "oops/oop.inline.hpp"
43 #include "runtime/atomic.hpp"
44 #include "runtime/globals_extension.hpp"
45 #include "runtime/java.hpp"
46 #include "runtime/mutexLocker.hpp"
47 #include "runtime/os.hpp"
48 #include "runtime/safepoint.hpp"
49 #include "utilities/powerOfTwo.hpp"
50
51
52 size_t ShenandoahHeapRegion::RegionCount = 0;
53 size_t ShenandoahHeapRegion::RegionSizeBytes = 0;
54 size_t ShenandoahHeapRegion::RegionSizeWords = 0;
55 size_t ShenandoahHeapRegion::RegionSizeBytesShift = 0;
56 size_t ShenandoahHeapRegion::RegionSizeWordsShift = 0;
57 size_t ShenandoahHeapRegion::RegionSizeBytesMask = 0;
58 size_t ShenandoahHeapRegion::RegionSizeWordsMask = 0;
59 size_t ShenandoahHeapRegion::HumongousThresholdBytes = 0;
60 size_t ShenandoahHeapRegion::HumongousThresholdWords = 0;
61 size_t ShenandoahHeapRegion::MaxTLABSizeBytes = 0;
62 size_t ShenandoahHeapRegion::MaxTLABSizeWords = 0;
63
64 ShenandoahHeapRegion::ShenandoahHeapRegion(HeapWord* start, size_t index, bool committed) :
65 _index(index),
66 _bottom(start),
67 _end(start + RegionSizeWords),
68 _new_top(NULL),
69 _empty_time(os::elapsedTime()),
70 _state(committed ? _empty_committed : _empty_uncommitted),
71 _top(start),
72 _tlab_allocs(0),
73 _gclab_allocs(0),
74 _plab_allocs(0),
75 _has_young_lab(false),
76 _live_data(0),
77 _critical_pins(0),
78 _update_watermark(start),
79 _affiliation(FREE),
80 _age(0) {
81
82 assert(Universe::on_page_boundary(_bottom) && Universe::on_page_boundary(_end),
83 "invalid space boundaries");
84 if (ZapUnusedHeapArea && committed) {
85 SpaceMangler::mangle_region(MemRegion(_bottom, _end));
86 }
87 }
88
89 void ShenandoahHeapRegion::report_illegal_transition(const char *method) {
90 ResourceMark rm;
91 stringStream ss;
92 ss.print("Illegal region state transition from \"%s\", at %s\n ", region_state_to_string(_state), method);
93 print_on(&ss);
94 fatal("%s", ss.as_string());
95 }
96
97 void ShenandoahHeapRegion::make_regular_allocation(ShenandoahRegionAffiliation affiliation) {
98 shenandoah_assert_heaplocked();
99 reset_age();
100 switch (_state) {
101 case _empty_uncommitted:
102 do_commit();
103 case _empty_committed:
104 set_affiliation(affiliation);
105 set_state(_regular);
106 case _regular:
107 case _pinned:
108 return;
109 default:
110 report_illegal_transition("regular allocation");
111 }
112 }
113
114 // Change affiliation to YOUNG_GENERATION if _state is not _pinned_cset, _regular, or _pinned. This implements
115 // behavior previously performed as a side effect of make_regular_bypass().
116 void ShenandoahHeapRegion::make_young_maybe() {
117 switch (_state) {
118 case _empty_uncommitted:
119 case _empty_committed:
120 case _cset:
121 case _humongous_start:
122 case _humongous_cont:
123 set_affiliation(YOUNG_GENERATION);
124 return;
125 case _pinned_cset:
126 case _regular:
127 case _pinned:
128 return;
129 default:
130 assert(false, "Unexpected _state in make_young_maybe");
131 }
132 }
133
134 void ShenandoahHeapRegion::make_regular_bypass() {
135 shenandoah_assert_heaplocked();
136 assert (ShenandoahHeap::heap()->is_full_gc_in_progress() || ShenandoahHeap::heap()->is_degenerated_gc_in_progress(),
137 "only for full or degen GC");
138 reset_age();
139 switch (_state) {
140 case _empty_uncommitted:
141 do_commit();
142 case _empty_committed:
143 case _cset:
144 case _humongous_start:
145 case _humongous_cont:
146 set_state(_regular);
147 return;
148 case _pinned_cset:
149 set_state(_pinned);
150 return;
151 case _regular:
152 case _pinned:
153 return;
154 default:
155 report_illegal_transition("regular bypass");
156 }
157 }
158
159 void ShenandoahHeapRegion::make_humongous_start() {
160 shenandoah_assert_heaplocked();
161 reset_age();
162 switch (_state) {
163 case _empty_uncommitted:
164 do_commit();
165 case _empty_committed:
166 set_state(_humongous_start);
167 return;
168 default:
169 report_illegal_transition("humongous start allocation");
170 }
171 }
172
173 void ShenandoahHeapRegion::make_humongous_start_bypass(ShenandoahRegionAffiliation affiliation) {
174 shenandoah_assert_heaplocked();
175 assert (ShenandoahHeap::heap()->is_full_gc_in_progress(), "only for full GC");
176 set_affiliation(affiliation);
177 reset_age();
178 switch (_state) {
179 case _empty_committed:
180 case _regular:
181 case _humongous_start:
182 case _humongous_cont:
183 set_state(_humongous_start);
184 return;
185 default:
186 report_illegal_transition("humongous start bypass");
187 }
188 }
189
190 void ShenandoahHeapRegion::make_humongous_cont() {
191 shenandoah_assert_heaplocked();
192 reset_age();
193 switch (_state) {
194 case _empty_uncommitted:
195 do_commit();
196 case _empty_committed:
197 set_state(_humongous_cont);
198 return;
199 default:
200 report_illegal_transition("humongous continuation allocation");
201 }
202 }
203
204 void ShenandoahHeapRegion::make_humongous_cont_bypass(ShenandoahRegionAffiliation affiliation) {
205 shenandoah_assert_heaplocked();
206 assert (ShenandoahHeap::heap()->is_full_gc_in_progress(), "only for full GC");
207 set_affiliation(affiliation);
208 reset_age();
209 switch (_state) {
210 case _empty_committed:
211 case _regular:
212 case _humongous_start:
213 case _humongous_cont:
214 set_state(_humongous_cont);
215 return;
216 default:
217 report_illegal_transition("humongous continuation bypass");
218 }
219 }
220
221 void ShenandoahHeapRegion::make_pinned() {
222 shenandoah_assert_heaplocked();
223 assert(pin_count() > 0, "Should have pins: " SIZE_FORMAT, pin_count());
224
225 switch (_state) {
226 case _regular:
227 set_state(_pinned);
228 case _pinned_cset:
229 case _pinned:
230 return;
231 case _humongous_start:
232 set_state(_pinned_humongous_start);
233 case _pinned_humongous_start:
234 return;
235 case _cset:
236 _state = _pinned_cset;
237 return;
238 default:
239 report_illegal_transition("pinning");
240 }
241 }
242
243 void ShenandoahHeapRegion::make_unpinned() {
244 shenandoah_assert_heaplocked();
245 assert(pin_count() == 0, "Should not have pins: " SIZE_FORMAT, pin_count());
246
247 switch (_state) {
248 case _pinned:
249 assert(affiliation() != FREE, "Pinned region should not be FREE");
250 set_state(_regular);
251 return;
252 case _regular:
253 case _humongous_start:
254 return;
255 case _pinned_cset:
256 set_state(_cset);
257 return;
258 case _pinned_humongous_start:
259 set_state(_humongous_start);
260 return;
261 default:
262 report_illegal_transition("unpinning");
263 }
264 }
265
266 void ShenandoahHeapRegion::make_cset() {
267 shenandoah_assert_heaplocked();
268 // Leave age untouched. We need to consult the age when we are deciding whether to promote evacuated objects.
269 switch (_state) {
270 case _regular:
271 set_state(_cset);
272 case _cset:
273 return;
274 default:
275 report_illegal_transition("cset");
276 }
277 }
278
279 void ShenandoahHeapRegion::make_trash() {
280 shenandoah_assert_heaplocked();
281 reset_age();
282 switch (_state) {
283 case _cset:
284 // Reclaiming cset regions
285 case _humongous_start:
286 case _humongous_cont:
287 // Reclaiming humongous regions
288 case _regular:
289 // Immediate region reclaim
290 set_state(_trash);
291 return;
292 default:
293 report_illegal_transition("trashing");
294 }
295 }
296
297 void ShenandoahHeapRegion::make_trash_immediate() {
298 make_trash();
299
300 // On this path, we know there are no marked objects in the region,
301 // tell marking context about it to bypass bitmap resets.
302 assert(ShenandoahHeap::heap()->active_generation()->is_mark_complete(), "Marking should be complete here.");
303 ShenandoahHeap::heap()->marking_context()->reset_top_bitmap(this);
304 }
305
306 void ShenandoahHeapRegion::make_empty() {
307 shenandoah_assert_heaplocked();
308 reset_age();
309 switch (_state) {
310 case _trash:
311 set_state(_empty_committed);
312 _empty_time = os::elapsedTime();
313 return;
314 default:
315 report_illegal_transition("emptying");
316 }
317 }
318
319 void ShenandoahHeapRegion::make_uncommitted() {
320 shenandoah_assert_heaplocked();
321 switch (_state) {
322 case _empty_committed:
323 do_uncommit();
324 set_state(_empty_uncommitted);
325 return;
326 default:
327 report_illegal_transition("uncommiting");
328 }
329 }
330
331 void ShenandoahHeapRegion::make_committed_bypass() {
332 shenandoah_assert_heaplocked();
333 assert (ShenandoahHeap::heap()->is_full_gc_in_progress(), "only for full GC");
334
335 switch (_state) {
336 case _empty_uncommitted:
337 do_commit();
338 set_state(_empty_committed);
339 return;
340 default:
341 report_illegal_transition("commit bypass");
342 }
343 }
344
345 void ShenandoahHeapRegion::reset_alloc_metadata() {
346 _tlab_allocs = 0;
347 _gclab_allocs = 0;
348 _plab_allocs = 0;
349 }
350
351 size_t ShenandoahHeapRegion::get_shared_allocs() const {
352 return used() - (_tlab_allocs + _gclab_allocs + _plab_allocs) * HeapWordSize;
353 }
354
355 size_t ShenandoahHeapRegion::get_tlab_allocs() const {
356 return _tlab_allocs * HeapWordSize;
357 }
358
359 size_t ShenandoahHeapRegion::get_gclab_allocs() const {
360 return _gclab_allocs * HeapWordSize;
361 }
362
363 size_t ShenandoahHeapRegion::get_plab_allocs() const {
364 return _plab_allocs * HeapWordSize;
365 }
366
367 void ShenandoahHeapRegion::set_live_data(size_t s) {
368 assert(Thread::current()->is_VM_thread(), "by VM thread");
369 _live_data = (s >> LogHeapWordSize);
370 }
371
372 void ShenandoahHeapRegion::print_on(outputStream* st) const {
373 st->print("|");
374 st->print(SIZE_FORMAT_W(5), this->_index);
375
376 switch (_state) {
377 case _empty_uncommitted:
378 st->print("|EU ");
379 break;
380 case _empty_committed:
381 st->print("|EC ");
382 break;
383 case _regular:
384 st->print("|R ");
385 break;
386 case _humongous_start:
387 st->print("|H ");
388 break;
389 case _pinned_humongous_start:
390 st->print("|HP ");
391 break;
392 case _humongous_cont:
393 st->print("|HC ");
394 break;
395 case _cset:
396 st->print("|CS ");
397 break;
398 case _trash:
399 st->print("|T ");
400 break;
401 case _pinned:
402 st->print("|P ");
403 break;
404 case _pinned_cset:
405 st->print("|CSP");
406 break;
407 default:
408 ShouldNotReachHere();
409 }
410 switch (_affiliation) {
411 case ShenandoahRegionAffiliation::FREE:
412 st->print("|F");
413 break;
414 case ShenandoahRegionAffiliation::YOUNG_GENERATION:
415 st->print("|Y");
416 break;
417 case ShenandoahRegionAffiliation::OLD_GENERATION:
418 st->print("|O");
419 break;
420 default:
421 ShouldNotReachHere();
422 }
423 st->print("|BTE " INTPTR_FORMAT_W(12) ", " INTPTR_FORMAT_W(12) ", " INTPTR_FORMAT_W(12),
424 p2i(bottom()), p2i(top()), p2i(end()));
425 st->print("|TAMS " INTPTR_FORMAT_W(12),
426 p2i(ShenandoahHeap::heap()->marking_context()->top_at_mark_start(const_cast<ShenandoahHeapRegion*>(this))));
427 st->print("|UWM " INTPTR_FORMAT_W(12),
428 p2i(_update_watermark));
429 st->print("|U " SIZE_FORMAT_W(5) "%1s", byte_size_in_proper_unit(used()), proper_unit_for_byte_size(used()));
430 st->print("|T " SIZE_FORMAT_W(5) "%1s", byte_size_in_proper_unit(get_tlab_allocs()), proper_unit_for_byte_size(get_tlab_allocs()));
431 st->print("|G " SIZE_FORMAT_W(5) "%1s", byte_size_in_proper_unit(get_gclab_allocs()), proper_unit_for_byte_size(get_gclab_allocs()));
432 if (ShenandoahHeap::heap()->mode()->is_generational()) {
433 st->print("|G " SIZE_FORMAT_W(5) "%1s", byte_size_in_proper_unit(get_plab_allocs()), proper_unit_for_byte_size(get_plab_allocs()));
434 }
435 st->print("|S " SIZE_FORMAT_W(5) "%1s", byte_size_in_proper_unit(get_shared_allocs()), proper_unit_for_byte_size(get_shared_allocs()));
436 st->print("|L " SIZE_FORMAT_W(5) "%1s", byte_size_in_proper_unit(get_live_data_bytes()), proper_unit_for_byte_size(get_live_data_bytes()));
437 st->print("|CP " SIZE_FORMAT_W(3), pin_count());
438 st->cr();
439 }
440
441 // oop_iterate without closure and without cancellation. always return true.
442 bool ShenandoahHeapRegion::oop_fill_and_coalesce_wo_cancel() {
443 HeapWord* obj_addr = resume_coalesce_and_fill();
444
445 assert(!is_humongous(), "No need to fill or coalesce humongous regions");
446 if (!is_active()) {
447 end_preemptible_coalesce_and_fill();
448 return true;
449 }
450
451 ShenandoahHeap* heap = ShenandoahHeap::heap();
452 ShenandoahMarkingContext* marking_context = heap->marking_context();
453 // All objects above TAMS are considered live even though their mark bits will not be set. Note that young-
454 // gen evacuations that interrupt a long-running old-gen concurrent mark may promote objects into old-gen
455 // while the old-gen concurrent marking is ongoing. These newly promoted objects will reside above TAMS
456 // and will be treated as live during the current old-gen marking pass, even though they will not be
457 // explicitly marked.
458 HeapWord* t = marking_context->top_at_mark_start(this);
459
460 // Expect marking to be completed before these threads invoke this service.
461 assert(heap->active_generation()->is_mark_complete(), "sanity");
462 while (obj_addr < t) {
463 oop obj = cast_to_oop(obj_addr);
464 if (marking_context->is_marked(obj)) {
465 assert(obj->klass() != NULL, "klass should not be NULL");
466 obj_addr += obj->size();
467 } else {
468 // Object is not marked. Coalesce and fill dead object with dead neighbors.
469 HeapWord* next_marked_obj = marking_context->get_next_marked_addr(obj_addr, t);
470 assert(next_marked_obj <= t, "next marked object cannot exceed top");
471 size_t fill_size = next_marked_obj - obj_addr;
472 ShenandoahHeap::fill_with_object(obj_addr, fill_size);
473 heap->card_scan()->coalesce_objects(obj_addr, fill_size);
474 obj_addr = next_marked_obj;
475 }
476 }
477 // Mark that this region has been coalesced and filled
478 end_preemptible_coalesce_and_fill();
479 return true;
480 }
481
482 // oop_iterate without closure, return true if completed without cancellation
483 bool ShenandoahHeapRegion::oop_fill_and_coalesce() {
484 HeapWord* obj_addr = resume_coalesce_and_fill();
485 // Consider yielding to cancel/preemption request after this many coalesce operations (skip marked, or coalesce free).
486 const size_t preemption_stride = 128;
487
488 assert(!is_humongous(), "No need to fill or coalesce humongous regions");
489 if (!is_active()) {
490 end_preemptible_coalesce_and_fill();
491 return true;
492 }
493
494 ShenandoahHeap* heap = ShenandoahHeap::heap();
495 ShenandoahMarkingContext* marking_context = heap->marking_context();
496 // All objects above TAMS are considered live even though their mark bits will not be set. Note that young-
497 // gen evacuations that interrupt a long-running old-gen concurrent mark may promote objects into old-gen
498 // while the old-gen concurrent marking is ongoing. These newly promoted objects will reside above TAMS
499 // and will be treated as live during the current old-gen marking pass, even though they will not be
500 // explicitly marked.
501 HeapWord* t = marking_context->top_at_mark_start(this);
502
503 // Expect marking to be completed before these threads invoke this service.
504 assert(heap->active_generation()->is_mark_complete(), "sanity");
505
506 size_t ops_before_preempt_check = preemption_stride;
507 while (obj_addr < t) {
508 oop obj = cast_to_oop(obj_addr);
509 if (marking_context->is_marked(obj)) {
510 assert(obj->klass() != NULL, "klass should not be NULL");
511 obj_addr += obj->size();
512 } else {
513 // Object is not marked. Coalesce and fill dead object with dead neighbors.
514 HeapWord* next_marked_obj = marking_context->get_next_marked_addr(obj_addr, t);
515 assert(next_marked_obj <= t, "next marked object cannot exceed top");
516 size_t fill_size = next_marked_obj - obj_addr;
517 ShenandoahHeap::fill_with_object(obj_addr, fill_size);
518 heap->card_scan()->coalesce_objects(obj_addr, fill_size);
519 obj_addr = next_marked_obj;
520 }
521 if (ops_before_preempt_check-- == 0) {
522 if (heap->cancelled_gc()) {
523 suspend_coalesce_and_fill(obj_addr);
524 return false;
525 }
526 ops_before_preempt_check = preemption_stride;
527 }
528 }
529 // Mark that this region has been coalesced and filled
530 end_preemptible_coalesce_and_fill();
531 return true;
532 }
533
534 void ShenandoahHeapRegion::global_oop_iterate_and_fill_dead(OopIterateClosure* blk) {
535 if (!is_active()) return;
536 if (is_humongous()) {
537 // No need to fill dead within humongous regions. Either the entire region is dead, or the entire region is
538 // unchanged. A humongous region holds no more than one humongous object.
539 oop_iterate_humongous(blk);
540 } else {
541 global_oop_iterate_objects_and_fill_dead(blk);
542 }
543 }
544
545 void ShenandoahHeapRegion::global_oop_iterate_objects_and_fill_dead(OopIterateClosure* blk) {
546 assert(!is_humongous(), "no humongous region here");
547 HeapWord* obj_addr = bottom();
548
549 ShenandoahHeap* heap = ShenandoahHeap::heap();
550 ShenandoahMarkingContext* marking_context = heap->marking_context();
551 RememberedScanner* rem_set_scanner = heap->card_scan();
552 // Objects allocated above TAMS are not marked, but are considered live for purposes of current GC efforts.
553 HeapWord* t = marking_context->top_at_mark_start(this);
554
555 assert(heap->active_generation()->is_mark_complete(), "sanity");
556
557 while (obj_addr < t) {
558 oop obj = cast_to_oop(obj_addr);
559 if (marking_context->is_marked(obj)) {
560 assert(obj->klass() != NULL, "klass should not be NULL");
561 // when promoting an entire region, we have to register the marked objects as well
562 obj_addr += obj->oop_iterate_size(blk);
563 } else {
564 // Object is not marked. Coalesce and fill dead object with dead neighbors.
565 HeapWord* next_marked_obj = marking_context->get_next_marked_addr(obj_addr, t);
566 assert(next_marked_obj <= t, "next marked object cannot exceed top");
567 size_t fill_size = next_marked_obj - obj_addr;
568 ShenandoahHeap::fill_with_object(obj_addr, fill_size);
569
570 // coalesce_objects() unregisters all but first object subsumed within coalesced range.
571 rem_set_scanner->coalesce_objects(obj_addr, fill_size);
572 obj_addr = next_marked_obj;
573 }
574 }
575
576 // Any object above TAMS and below top() is considered live.
577 t = top();
578 while (obj_addr < t) {
579 oop obj = cast_to_oop(obj_addr);
580 obj_addr += obj->oop_iterate_size(blk);
581 }
582 }
583
584 // DO NOT CANCEL. If this worker thread has accepted responsibility for scanning a particular range of addresses, it
585 // must finish the work before it can be cancelled.
586 void ShenandoahHeapRegion::oop_iterate_humongous_slice(OopIterateClosure* blk, bool dirty_only,
587 HeapWord* start, size_t words, bool write_table, bool is_concurrent) {
588 assert(words % CardTable::card_size_in_words() == 0, "Humongous iteration must span whole number of cards");
589 assert(is_humongous(), "only humongous region here");
590 ShenandoahHeap* heap = ShenandoahHeap::heap();
591
592 // Find head.
593 ShenandoahHeapRegion* r = humongous_start_region();
594 assert(r->is_humongous_start(), "need humongous head here");
595 assert(CardTable::card_size_in_words() * (words / CardTable::card_size_in_words()) == words,
596 "slice must be integral number of cards");
597
598 oop obj = cast_to_oop(r->bottom());
599 RememberedScanner* scanner = ShenandoahHeap::heap()->card_scan();
600 size_t card_index = scanner->card_index_for_addr(start);
601 size_t num_cards = words / CardTable::card_size_in_words();
602
603 if (dirty_only) {
604 if (write_table) {
605 while (num_cards-- > 0) {
606 if (scanner->is_write_card_dirty(card_index++)) {
607 obj->oop_iterate(blk, MemRegion(start, start + CardTable::card_size_in_words()));
608 }
609 start += CardTable::card_size_in_words();
610 }
611 } else {
612 while (num_cards-- > 0) {
613 if (scanner->is_card_dirty(card_index++)) {
614 obj->oop_iterate(blk, MemRegion(start, start + CardTable::card_size_in_words()));
615 }
616 start += CardTable::card_size_in_words();
617 }
618 }
619 } else {
620 // Scan all data, regardless of whether cards are dirty
621 obj->oop_iterate(blk, MemRegion(start, start + num_cards * CardTable::card_size_in_words()));
622 }
623 }
624
625 void ShenandoahHeapRegion::oop_iterate_humongous(OopIterateClosure* blk, HeapWord* start, size_t words) {
626 assert(is_humongous(), "only humongous region here");
627 // Find head.
628 ShenandoahHeapRegion* r = humongous_start_region();
629 assert(r->is_humongous_start(), "need humongous head here");
630 oop obj = cast_to_oop(r->bottom());
631 obj->oop_iterate(blk, MemRegion(start, start + words));
632 }
633
634 void ShenandoahHeapRegion::oop_iterate_humongous(OopIterateClosure* blk) {
635 assert(is_humongous(), "only humongous region here");
636 // Find head.
637 ShenandoahHeapRegion* r = humongous_start_region();
638 assert(r->is_humongous_start(), "need humongous head here");
639 oop obj = cast_to_oop(r->bottom());
640 obj->oop_iterate(blk, MemRegion(bottom(), top()));
641 }
642
643 ShenandoahHeapRegion* ShenandoahHeapRegion::humongous_start_region() const {
644 ShenandoahHeap* heap = ShenandoahHeap::heap();
645 assert(is_humongous(), "Must be a part of the humongous region");
646 size_t i = index();
647 ShenandoahHeapRegion* r = const_cast<ShenandoahHeapRegion*>(this);
648 while (!r->is_humongous_start()) {
649 assert(i > 0, "Sanity");
650 i--;
651 r = heap->get_region(i);
652 assert(r->is_humongous(), "Must be a part of the humongous region");
653 }
654 assert(r->is_humongous_start(), "Must be");
655 return r;
656 }
657
658 void ShenandoahHeapRegion::recycle() {
659 ShenandoahHeap* heap = ShenandoahHeap::heap();
660
661 if (affiliation() == YOUNG_GENERATION) {
662 heap->young_generation()->decrease_used(used());
663 } else if (affiliation() == OLD_GENERATION) {
664 heap->old_generation()->decrease_used(used());
665 }
666
667 set_top(bottom());
668 clear_live_data();
669
670 reset_alloc_metadata();
671
672 heap->marking_context()->reset_top_at_mark_start(this);
673 set_update_watermark(bottom());
674
675 make_empty();
676 set_affiliation(FREE);
677
678 if (ZapUnusedHeapArea) {
679 SpaceMangler::mangle_region(MemRegion(bottom(), end()));
680 }
681 }
682
683 HeapWord* ShenandoahHeapRegion::block_start(const void* p) const {
684 assert(MemRegion(bottom(), end()).contains(p),
685 "p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")",
686 p2i(p), p2i(bottom()), p2i(end()));
687 if (p >= top()) {
688 return top();
689 } else {
690 HeapWord* last = bottom();
691 HeapWord* cur = last;
692 while (cur <= p) {
693 last = cur;
694 cur += cast_to_oop(cur)->size();
695 }
696 shenandoah_assert_correct(NULL, cast_to_oop(last));
697 return last;
698 }
699 }
700
701 size_t ShenandoahHeapRegion::block_size(const HeapWord* p) const {
702 assert(MemRegion(bottom(), end()).contains(p),
703 "p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")",
704 p2i(p), p2i(bottom()), p2i(end()));
705 if (p < top()) {
706 return cast_to_oop(p)->size();
707 } else {
708 assert(p == top(), "just checking");
709 return pointer_delta(end(), (HeapWord*) p);
710 }
711 }
712
713 size_t ShenandoahHeapRegion::setup_sizes(size_t max_heap_size) {
714 // Absolute minimums we should not ever break.
715 static const size_t MIN_REGION_SIZE = 256*K;
716
717 if (FLAG_IS_DEFAULT(ShenandoahMinRegionSize)) {
718 FLAG_SET_DEFAULT(ShenandoahMinRegionSize, MIN_REGION_SIZE);
719 }
720
721 size_t region_size;
722 if (FLAG_IS_DEFAULT(ShenandoahRegionSize)) {
723 if (ShenandoahMinRegionSize > max_heap_size / MIN_NUM_REGIONS) {
724 err_msg message("Max heap size (" SIZE_FORMAT "%s) is too low to afford the minimum number "
725 "of regions (" SIZE_FORMAT ") of minimum region size (" SIZE_FORMAT "%s).",
726 byte_size_in_proper_unit(max_heap_size), proper_unit_for_byte_size(max_heap_size),
727 MIN_NUM_REGIONS,
728 byte_size_in_proper_unit(ShenandoahMinRegionSize), proper_unit_for_byte_size(ShenandoahMinRegionSize));
729 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize option", message);
730 }
731 if (ShenandoahMinRegionSize < MIN_REGION_SIZE) {
732 err_msg message("" SIZE_FORMAT "%s should not be lower than minimum region size (" SIZE_FORMAT "%s).",
733 byte_size_in_proper_unit(ShenandoahMinRegionSize), proper_unit_for_byte_size(ShenandoahMinRegionSize),
734 byte_size_in_proper_unit(MIN_REGION_SIZE), proper_unit_for_byte_size(MIN_REGION_SIZE));
735 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize option", message);
736 }
737 if (ShenandoahMinRegionSize < MinTLABSize) {
738 err_msg message("" SIZE_FORMAT "%s should not be lower than TLAB size size (" SIZE_FORMAT "%s).",
739 byte_size_in_proper_unit(ShenandoahMinRegionSize), proper_unit_for_byte_size(ShenandoahMinRegionSize),
740 byte_size_in_proper_unit(MinTLABSize), proper_unit_for_byte_size(MinTLABSize));
741 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize option", message);
742 }
743 if (ShenandoahMaxRegionSize < MIN_REGION_SIZE) {
744 err_msg message("" SIZE_FORMAT "%s should not be lower than min region size (" SIZE_FORMAT "%s).",
745 byte_size_in_proper_unit(ShenandoahMaxRegionSize), proper_unit_for_byte_size(ShenandoahMaxRegionSize),
746 byte_size_in_proper_unit(MIN_REGION_SIZE), proper_unit_for_byte_size(MIN_REGION_SIZE));
747 vm_exit_during_initialization("Invalid -XX:ShenandoahMaxRegionSize option", message);
748 }
749 if (ShenandoahMinRegionSize > ShenandoahMaxRegionSize) {
750 err_msg message("Minimum (" SIZE_FORMAT "%s) should be larger than maximum (" SIZE_FORMAT "%s).",
751 byte_size_in_proper_unit(ShenandoahMinRegionSize), proper_unit_for_byte_size(ShenandoahMinRegionSize),
752 byte_size_in_proper_unit(ShenandoahMaxRegionSize), proper_unit_for_byte_size(ShenandoahMaxRegionSize));
753 vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize or -XX:ShenandoahMaxRegionSize", message);
754 }
755
756 // We rapidly expand to max_heap_size in most scenarios, so that is the measure
757 // for usual heap sizes. Do not depend on initial_heap_size here.
758 region_size = max_heap_size / ShenandoahTargetNumRegions;
759
760 // Now make sure that we don't go over or under our limits.
761 region_size = MAX2(ShenandoahMinRegionSize, region_size);
762 region_size = MIN2(ShenandoahMaxRegionSize, region_size);
763
764 } else {
765 if (ShenandoahRegionSize > max_heap_size / MIN_NUM_REGIONS) {
766 err_msg message("Max heap size (" SIZE_FORMAT "%s) is too low to afford the minimum number "
767 "of regions (" SIZE_FORMAT ") of requested size (" SIZE_FORMAT "%s).",
768 byte_size_in_proper_unit(max_heap_size), proper_unit_for_byte_size(max_heap_size),
769 MIN_NUM_REGIONS,
770 byte_size_in_proper_unit(ShenandoahRegionSize), proper_unit_for_byte_size(ShenandoahRegionSize));
771 vm_exit_during_initialization("Invalid -XX:ShenandoahRegionSize option", message);
772 }
773 if (ShenandoahRegionSize < ShenandoahMinRegionSize) {
774 err_msg message("Heap region size (" SIZE_FORMAT "%s) should be larger than min region size (" SIZE_FORMAT "%s).",
775 byte_size_in_proper_unit(ShenandoahRegionSize), proper_unit_for_byte_size(ShenandoahRegionSize),
776 byte_size_in_proper_unit(ShenandoahMinRegionSize), proper_unit_for_byte_size(ShenandoahMinRegionSize));
777 vm_exit_during_initialization("Invalid -XX:ShenandoahRegionSize option", message);
778 }
779 if (ShenandoahRegionSize > ShenandoahMaxRegionSize) {
780 err_msg message("Heap region size (" SIZE_FORMAT "%s) should be lower than max region size (" SIZE_FORMAT "%s).",
781 byte_size_in_proper_unit(ShenandoahRegionSize), proper_unit_for_byte_size(ShenandoahRegionSize),
782 byte_size_in_proper_unit(ShenandoahMaxRegionSize), proper_unit_for_byte_size(ShenandoahMaxRegionSize));
783 vm_exit_during_initialization("Invalid -XX:ShenandoahRegionSize option", message);
784 }
785 region_size = ShenandoahRegionSize;
786 }
787
788 // Make sure region size and heap size are page aligned.
789 // If large pages are used, we ensure that region size is aligned to large page size if
790 // heap size is large enough to accommodate minimal number of regions. Otherwise, we align
791 // region size to regular page size.
792
793 // Figure out page size to use, and aligns up heap to page size
794 int page_size = os::vm_page_size();
795 if (UseLargePages) {
796 size_t large_page_size = os::large_page_size();
797 max_heap_size = align_up(max_heap_size, large_page_size);
798 if ((max_heap_size / align_up(region_size, large_page_size)) >= MIN_NUM_REGIONS) {
799 page_size = (int)large_page_size;
800 } else {
801 // Should have been checked during argument initialization
802 assert(!ShenandoahUncommit, "Uncommit requires region size aligns to large page size");
803 }
804 } else {
805 max_heap_size = align_up(max_heap_size, page_size);
806 }
807
808 // Align region size to page size
809 region_size = align_up(region_size, page_size);
810
811 int region_size_log = log2i(region_size);
812 // Recalculate the region size to make sure it's a power of
813 // 2. This means that region_size is the largest power of 2 that's
814 // <= what we've calculated so far.
815 region_size = size_t(1) << region_size_log;
816
817 // Now, set up the globals.
818 guarantee(RegionSizeBytesShift == 0, "we should only set it once");
819 RegionSizeBytesShift = (size_t)region_size_log;
820
821 guarantee(RegionSizeWordsShift == 0, "we should only set it once");
822 RegionSizeWordsShift = RegionSizeBytesShift - LogHeapWordSize;
823
824 guarantee(RegionSizeBytes == 0, "we should only set it once");
825 RegionSizeBytes = region_size;
826 RegionSizeWords = RegionSizeBytes >> LogHeapWordSize;
827 assert (RegionSizeWords*HeapWordSize == RegionSizeBytes, "sanity");
828
829 guarantee(RegionSizeWordsMask == 0, "we should only set it once");
830 RegionSizeWordsMask = RegionSizeWords - 1;
831
832 guarantee(RegionSizeBytesMask == 0, "we should only set it once");
833 RegionSizeBytesMask = RegionSizeBytes - 1;
834
835 guarantee(RegionCount == 0, "we should only set it once");
836 RegionCount = align_up(max_heap_size, RegionSizeBytes) / RegionSizeBytes;
837 guarantee(RegionCount >= MIN_NUM_REGIONS, "Should have at least minimum regions");
838
839 guarantee(HumongousThresholdWords == 0, "we should only set it once");
840 HumongousThresholdWords = RegionSizeWords * ShenandoahHumongousThreshold / 100;
841 HumongousThresholdWords = align_down(HumongousThresholdWords, MinObjAlignment);
842 assert (HumongousThresholdWords <= RegionSizeWords, "sanity");
843
844 guarantee(HumongousThresholdBytes == 0, "we should only set it once");
845 HumongousThresholdBytes = HumongousThresholdWords * HeapWordSize;
846 assert (HumongousThresholdBytes <= RegionSizeBytes, "sanity");
847
848 // The rationale for trimming the TLAB sizes has to do with the raciness in
849 // TLAB allocation machinery. It may happen that TLAB sizing policy polls Shenandoah
850 // about next free size, gets the answer for region #N, goes away for a while, then
851 // tries to allocate in region #N, and fail because some other thread have claimed part
852 // of the region #N, and then the freeset allocation code has to retire the region #N,
853 // before moving the allocation to region #N+1.
854 //
855 // The worst case realizes when "answer" is "region size", which means it could
856 // prematurely retire an entire region. Having smaller TLABs does not fix that
857 // completely, but reduces the probability of too wasteful region retirement.
858 // With current divisor, we will waste no more than 1/8 of region size in the worst
859 // case. This also has a secondary effect on collection set selection: even under
860 // the race, the regions would be at least 7/8 used, which allows relying on
861 // "used" - "live" for cset selection. Otherwise, we can get the fragmented region
862 // below the garbage threshold that would never be considered for collection.
863 //
864 // The whole thing is mitigated if Elastic TLABs are enabled.
865 //
866 guarantee(MaxTLABSizeWords == 0, "we should only set it once");
867 MaxTLABSizeWords = MIN2(ShenandoahElasticTLAB ? RegionSizeWords : (RegionSizeWords / 8), HumongousThresholdWords);
868 MaxTLABSizeWords = align_down(MaxTLABSizeWords, MinObjAlignment);
869
870 guarantee(MaxTLABSizeBytes == 0, "we should only set it once");
871 MaxTLABSizeBytes = MaxTLABSizeWords * HeapWordSize;
872 assert (MaxTLABSizeBytes > MinTLABSize, "should be larger");
873
874 return max_heap_size;
875 }
876
877 void ShenandoahHeapRegion::do_commit() {
878 ShenandoahHeap* heap = ShenandoahHeap::heap();
879 if (!heap->is_heap_region_special() && !os::commit_memory((char *) bottom(), RegionSizeBytes, false)) {
880 report_java_out_of_memory("Unable to commit region");
881 }
882 if (!heap->commit_bitmap_slice(this)) {
883 report_java_out_of_memory("Unable to commit bitmaps for region");
884 }
885 if (AlwaysPreTouch) {
886 os::pretouch_memory(bottom(), end(), heap->pretouch_heap_page_size());
887 }
888 heap->increase_committed(ShenandoahHeapRegion::region_size_bytes());
889 }
890
891 void ShenandoahHeapRegion::do_uncommit() {
892 ShenandoahHeap* heap = ShenandoahHeap::heap();
893 if (!heap->is_heap_region_special() && !os::uncommit_memory((char *) bottom(), RegionSizeBytes)) {
894 report_java_out_of_memory("Unable to uncommit region");
895 }
896 if (!heap->uncommit_bitmap_slice(this)) {
897 report_java_out_of_memory("Unable to uncommit bitmaps for region");
898 }
899 heap->decrease_committed(ShenandoahHeapRegion::region_size_bytes());
900 }
901
902 void ShenandoahHeapRegion::set_state(RegionState to) {
903 EventShenandoahHeapRegionStateChange evt;
904 if (evt.should_commit()){
905 evt.set_index((unsigned) index());
906 evt.set_start((uintptr_t)bottom());
907 evt.set_used(used());
908 evt.set_from(_state);
909 evt.set_to(to);
910 evt.commit();
911 }
912 _state = to;
913 }
914
915 void ShenandoahHeapRegion::record_pin() {
916 Atomic::add(&_critical_pins, (size_t)1);
917 }
918
919 void ShenandoahHeapRegion::record_unpin() {
920 assert(pin_count() > 0, "Region " SIZE_FORMAT " should have non-zero pins", index());
921 Atomic::sub(&_critical_pins, (size_t)1);
922 }
923
924 size_t ShenandoahHeapRegion::pin_count() const {
925 return Atomic::load(&_critical_pins);
926 }
927
928 void ShenandoahHeapRegion::set_affiliation(ShenandoahRegionAffiliation new_affiliation) {
929 ShenandoahHeap* heap = ShenandoahHeap::heap();
930
931 {
932 ShenandoahMarkingContext* const ctx = heap->complete_marking_context();
933 log_debug(gc)("Setting affiliation of Region " SIZE_FORMAT " from %s to %s, top: " PTR_FORMAT ", TAMS: " PTR_FORMAT
934 ", watermark: " PTR_FORMAT ", top_bitmap: " PTR_FORMAT,
935 index(), affiliation_name(_affiliation), affiliation_name(new_affiliation),
936 p2i(top()), p2i(ctx->top_at_mark_start(this)), p2i(_update_watermark), p2i(ctx->top_bitmap(this)));
937 }
938
939 #ifdef ASSERT
940 {
941 // During full gc, heap->complete_marking_context() is not valid, may equal nullptr.
942 ShenandoahMarkingContext* const ctx = heap->complete_marking_context();
943 size_t idx = this->index();
944 HeapWord* top_bitmap = ctx->top_bitmap(this);
945
946 assert(ctx->is_bitmap_clear_range(top_bitmap, _end),
947 "Region " SIZE_FORMAT ", bitmap should be clear between top_bitmap: " PTR_FORMAT " and end: " PTR_FORMAT, idx,
948 p2i(top_bitmap), p2i(_end));
949 }
950 #endif
951
952 if (_affiliation == new_affiliation) {
953 return;
954 }
955
956 if (!heap->mode()->is_generational()) {
957 _affiliation = new_affiliation;
958 return;
959 }
960
961 log_trace(gc)("Changing affiliation of region %zu from %s to %s",
962 index(), affiliation_name(_affiliation), affiliation_name(new_affiliation));
963
964 if (_affiliation == ShenandoahRegionAffiliation::YOUNG_GENERATION) {
965 heap->young_generation()->decrement_affiliated_region_count();
966 } else if (_affiliation == ShenandoahRegionAffiliation::OLD_GENERATION) {
967 heap->old_generation()->decrement_affiliated_region_count();
968 }
969
970 switch (new_affiliation) {
971 case FREE:
972 assert(!has_live(), "Free region should not have live data");
973 break;
974 case YOUNG_GENERATION:
975 reset_age();
976 heap->young_generation()->increment_affiliated_region_count();
977 break;
978 case OLD_GENERATION:
979 heap->old_generation()->increment_affiliated_region_count();
980 break;
981 default:
982 ShouldNotReachHere();
983 return;
984 }
985 _affiliation = new_affiliation;
986 }
987
988 size_t ShenandoahHeapRegion::promote_humongous() {
989 ShenandoahHeap* heap = ShenandoahHeap::heap();
990 ShenandoahMarkingContext* marking_context = heap->marking_context();
991 assert(heap->active_generation()->is_mark_complete(), "sanity");
992 assert(is_young(), "Only young regions can be promoted");
993 assert(is_humongous_start(), "Should not promote humongous continuation in isolation");
994 assert(age() >= InitialTenuringThreshold, "Only promote regions that are sufficiently aged");
995
996 ShenandoahGeneration* old_generation = heap->old_generation();
997 ShenandoahGeneration* young_generation = heap->young_generation();
998
999 oop obj = cast_to_oop(bottom());
1000 assert(marking_context->is_marked(obj), "promoted humongous object should be alive");
1001
1002 size_t spanned_regions = ShenandoahHeapRegion::required_regions(obj->size() * HeapWordSize);
1003 size_t index_limit = index() + spanned_regions;
1004
1005 log_debug(gc)("promoting humongous region " SIZE_FORMAT ", spanning " SIZE_FORMAT, index(), spanned_regions);
1006
1007 // Since this region may have served previously as OLD, it may hold obsolete object range info.
1008 heap->card_scan()->reset_object_range(bottom(), bottom() + spanned_regions * ShenandoahHeapRegion::region_size_words());
1009 // Since the humongous region holds only one object, no lock is necessary for this register_object() invocation.
1010 heap->card_scan()->register_object_wo_lock(bottom());
1011
1012 // For this region and each humongous continuation region spanned by this humongous object, change
1013 // affiliation to OLD_GENERATION and adjust the generation-use tallies. The remnant of memory
1014 // in the last humongous region that is not spanned by obj is currently not used.
1015 for (size_t i = index(); i < index_limit; i++) {
1016 ShenandoahHeapRegion* r = heap->get_region(i);
1017 log_debug(gc)("promoting humongous region " SIZE_FORMAT ", from " PTR_FORMAT " to " PTR_FORMAT,
1018 r->index(), p2i(r->bottom()), p2i(r->top()));
1019 // We mark the entire humongous object's range as dirty after loop terminates, so no need to dirty the range here
1020 r->set_affiliation(OLD_GENERATION);
1021 old_generation->increase_used(r->used());
1022 young_generation->decrease_used(r->used());
1023 }
1024 if (obj->is_typeArray()) {
1025 // Primitive arrays don't need to be scanned. See above TODO question about requiring
1026 // region promotion at safepoint.
1027 log_debug(gc)("Clean cards for promoted humongous object (Region " SIZE_FORMAT ") from " PTR_FORMAT " to " PTR_FORMAT,
1028 index(), p2i(bottom()), p2i(bottom() + obj->size()));
1029 heap->card_scan()->mark_range_as_clean(bottom(), obj->size());
1030 } else {
1031 log_debug(gc)("Dirty cards for promoted humongous object (Region " SIZE_FORMAT ") from " PTR_FORMAT " to " PTR_FORMAT,
1032 index(), p2i(bottom()), p2i(bottom() + obj->size()));
1033 heap->card_scan()->mark_range_as_dirty(bottom(), obj->size());
1034 }
1035 return index_limit - index();
1036 }