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