1 /*
2 * Copyright (c) 2005, 2019, 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 "aot/aotLoader.hpp"
27 #include "classfile/classLoaderDataGraph.hpp"
28 #include "classfile/javaClasses.inline.hpp"
29 #include "classfile/stringTable.hpp"
30 #include "classfile/symbolTable.hpp"
31 #include "classfile/systemDictionary.hpp"
32 #include "code/codeCache.hpp"
33 #include "gc/parallel/gcTaskManager.hpp"
34 #include "gc/parallel/parallelArguments.hpp"
35 #include "gc/parallel/parallelScavengeHeap.inline.hpp"
36 #include "gc/parallel/parMarkBitMap.inline.hpp"
37 #include "gc/parallel/pcTasks.hpp"
38 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
39 #include "gc/parallel/psCompactionManager.inline.hpp"
40 #include "gc/parallel/psOldGen.hpp"
41 #include "gc/parallel/psParallelCompact.inline.hpp"
42 #include "gc/parallel/psPromotionManager.inline.hpp"
43 #include "gc/parallel/psScavenge.hpp"
44 #include "gc/parallel/psYoungGen.hpp"
45 #include "gc/shared/gcCause.hpp"
46 #include "gc/shared/gcHeapSummary.hpp"
47 #include "gc/shared/gcId.hpp"
48 #include "gc/shared/gcLocker.hpp"
49 #include "gc/shared/gcTimer.hpp"
50 #include "gc/shared/gcTrace.hpp"
51 #include "gc/shared/gcTraceTime.inline.hpp"
52 #include "gc/shared/isGCActiveMark.hpp"
53 #include "gc/shared/referencePolicy.hpp"
54 #include "gc/shared/referenceProcessor.hpp"
55 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
56 #include "gc/shared/spaceDecorator.hpp"
57 #include "gc/shared/weakProcessor.hpp"
58 #include "logging/log.hpp"
59 #include "memory/iterator.inline.hpp"
60 #include "memory/resourceArea.hpp"
61 #include "memory/universe.hpp"
62 #include "oops/access.inline.hpp"
63 #include "oops/instanceClassLoaderKlass.inline.hpp"
64 #include "oops/instanceKlass.inline.hpp"
65 #include "oops/instanceMirrorKlass.inline.hpp"
66 #include "oops/methodData.hpp"
67 #include "oops/objArrayKlass.inline.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "runtime/atomic.hpp"
70 #include "runtime/handles.inline.hpp"
71 #include "runtime/safepoint.hpp"
72 #include "runtime/vmThread.hpp"
73 #include "services/management.hpp"
74 #include "services/memTracker.hpp"
75 #include "services/memoryService.hpp"
76 #include "utilities/align.hpp"
77 #include "utilities/debug.hpp"
78 #include "utilities/events.hpp"
79 #include "utilities/formatBuffer.hpp"
80 #include "utilities/macros.hpp"
81 #include "utilities/stack.inline.hpp"
82 #if INCLUDE_JVMCI
83 #include "jvmci/jvmci.hpp"
84 #endif
85
86 #include <math.h>
87
88 // All sizes are in HeapWords.
89 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words
90 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
91 const size_t ParallelCompactData::RegionSizeBytes =
92 RegionSize << LogHeapWordSize;
93 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
94 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
95 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
96
97 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words
98 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize;
99 const size_t ParallelCompactData::BlockSizeBytes =
100 BlockSize << LogHeapWordSize;
101 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1;
102 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1;
103 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask;
104
105 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
106 const size_t ParallelCompactData::Log2BlocksPerRegion =
107 Log2RegionSize - Log2BlockSize;
108
109 const ParallelCompactData::RegionData::region_sz_t
110 ParallelCompactData::RegionData::dc_shift = 27;
111
112 const ParallelCompactData::RegionData::region_sz_t
113 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
114
115 const ParallelCompactData::RegionData::region_sz_t
116 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
117
118 const ParallelCompactData::RegionData::region_sz_t
119 ParallelCompactData::RegionData::los_mask = ~dc_mask;
120
121 const ParallelCompactData::RegionData::region_sz_t
122 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
123
124 const ParallelCompactData::RegionData::region_sz_t
125 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
126
127 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
128
129 SpanSubjectToDiscoveryClosure PSParallelCompact::_span_based_discoverer;
130 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
131
132 double PSParallelCompact::_dwl_mean;
133 double PSParallelCompact::_dwl_std_dev;
134 double PSParallelCompact::_dwl_first_term;
135 double PSParallelCompact::_dwl_adjustment;
136 #ifdef ASSERT
137 bool PSParallelCompact::_dwl_initialized = false;
138 #endif // #ifdef ASSERT
139
140 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
141 HeapWord* destination)
142 {
143 assert(src_region_idx != 0, "invalid src_region_idx");
144 assert(partial_obj_size != 0, "invalid partial_obj_size argument");
145 assert(destination != NULL, "invalid destination argument");
146
147 _src_region_idx = src_region_idx;
148 _partial_obj_size = partial_obj_size;
149 _destination = destination;
150
151 // These fields may not be updated below, so make sure they're clear.
152 assert(_dest_region_addr == NULL, "should have been cleared");
153 assert(_first_src_addr == NULL, "should have been cleared");
154
155 // Determine the number of destination regions for the partial object.
156 HeapWord* const last_word = destination + partial_obj_size - 1;
157 const ParallelCompactData& sd = PSParallelCompact::summary_data();
158 HeapWord* const beg_region_addr = sd.region_align_down(destination);
159 HeapWord* const end_region_addr = sd.region_align_down(last_word);
160
161 if (beg_region_addr == end_region_addr) {
162 // One destination region.
163 _destination_count = 1;
164 if (end_region_addr == destination) {
165 // The destination falls on a region boundary, thus the first word of the
166 // partial object will be the first word copied to the destination region.
167 _dest_region_addr = end_region_addr;
168 _first_src_addr = sd.region_to_addr(src_region_idx);
169 }
170 } else {
171 // Two destination regions. When copied, the partial object will cross a
172 // destination region boundary, so a word somewhere within the partial
173 // object will be the first word copied to the second destination region.
174 _destination_count = 2;
175 _dest_region_addr = end_region_addr;
176 const size_t ofs = pointer_delta(end_region_addr, destination);
177 assert(ofs < _partial_obj_size, "sanity");
178 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
179 }
180 }
181
182 void SplitInfo::clear()
183 {
184 _src_region_idx = 0;
185 _partial_obj_size = 0;
186 _destination = NULL;
187 _destination_count = 0;
188 _dest_region_addr = NULL;
189 _first_src_addr = NULL;
190 assert(!is_valid(), "sanity");
191 }
192
193 #ifdef ASSERT
194 void SplitInfo::verify_clear()
195 {
196 assert(_src_region_idx == 0, "not clear");
197 assert(_partial_obj_size == 0, "not clear");
198 assert(_destination == NULL, "not clear");
199 assert(_destination_count == 0, "not clear");
200 assert(_dest_region_addr == NULL, "not clear");
201 assert(_first_src_addr == NULL, "not clear");
202 }
203 #endif // #ifdef ASSERT
204
205
206 void PSParallelCompact::print_on_error(outputStream* st) {
207 _mark_bitmap.print_on_error(st);
208 }
209
210 #ifndef PRODUCT
211 const char* PSParallelCompact::space_names[] = {
212 "old ", "eden", "from", "to "
213 };
214
215 void PSParallelCompact::print_region_ranges() {
216 if (!log_develop_is_enabled(Trace, gc, compaction)) {
217 return;
218 }
219 Log(gc, compaction) log;
220 ResourceMark rm;
221 LogStream ls(log.trace());
222 Universe::print_on(&ls);
223 log.trace("space bottom top end new_top");
224 log.trace("------ ---------- ---------- ---------- ----------");
225
226 for (unsigned int id = 0; id < last_space_id; ++id) {
227 const MutableSpace* space = _space_info[id].space();
228 log.trace("%u %s "
229 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
230 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
231 id, space_names[id],
232 summary_data().addr_to_region_idx(space->bottom()),
233 summary_data().addr_to_region_idx(space->top()),
234 summary_data().addr_to_region_idx(space->end()),
235 summary_data().addr_to_region_idx(_space_info[id].new_top()));
236 }
237 }
238
239 void
240 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
241 {
242 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7)
243 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5)
244
245 ParallelCompactData& sd = PSParallelCompact::summary_data();
246 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
247 log_develop_trace(gc, compaction)(
248 REGION_IDX_FORMAT " " PTR_FORMAT " "
249 REGION_IDX_FORMAT " " PTR_FORMAT " "
250 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
251 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
252 i, p2i(c->data_location()), dci, p2i(c->destination()),
253 c->partial_obj_size(), c->live_obj_size(),
254 c->data_size(), c->source_region(), c->destination_count());
255
256 #undef REGION_IDX_FORMAT
257 #undef REGION_DATA_FORMAT
258 }
259
260 void
261 print_generic_summary_data(ParallelCompactData& summary_data,
262 HeapWord* const beg_addr,
263 HeapWord* const end_addr)
264 {
265 size_t total_words = 0;
266 size_t i = summary_data.addr_to_region_idx(beg_addr);
267 const size_t last = summary_data.addr_to_region_idx(end_addr);
268 HeapWord* pdest = 0;
269
270 while (i < last) {
271 ParallelCompactData::RegionData* c = summary_data.region(i);
272 if (c->data_size() != 0 || c->destination() != pdest) {
273 print_generic_summary_region(i, c);
274 total_words += c->data_size();
275 pdest = c->destination();
276 }
277 ++i;
278 }
279
280 log_develop_trace(gc, compaction)("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
281 }
282
283 void
284 PSParallelCompact::print_generic_summary_data(ParallelCompactData& summary_data,
285 HeapWord* const beg_addr,
286 HeapWord* const end_addr) {
287 ::print_generic_summary_data(summary_data,beg_addr, end_addr);
288 }
289
290 void
291 print_generic_summary_data(ParallelCompactData& summary_data,
292 SpaceInfo* space_info)
293 {
294 if (!log_develop_is_enabled(Trace, gc, compaction)) {
295 return;
296 }
297
298 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
299 const MutableSpace* space = space_info[id].space();
300 print_generic_summary_data(summary_data, space->bottom(),
301 MAX2(space->top(), space_info[id].new_top()));
302 }
303 }
304
305 void
306 print_initial_summary_data(ParallelCompactData& summary_data,
307 const MutableSpace* space) {
308 if (space->top() == space->bottom()) {
309 return;
310 }
311
312 const size_t region_size = ParallelCompactData::RegionSize;
313 typedef ParallelCompactData::RegionData RegionData;
314 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
315 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
316 const RegionData* c = summary_data.region(end_region - 1);
317 HeapWord* end_addr = c->destination() + c->data_size();
318 const size_t live_in_space = pointer_delta(end_addr, space->bottom());
319
320 // Print (and count) the full regions at the beginning of the space.
321 size_t full_region_count = 0;
322 size_t i = summary_data.addr_to_region_idx(space->bottom());
323 while (i < end_region && summary_data.region(i)->data_size() == region_size) {
324 ParallelCompactData::RegionData* c = summary_data.region(i);
325 log_develop_trace(gc, compaction)(
326 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
327 i, p2i(c->destination()),
328 c->partial_obj_size(), c->live_obj_size(),
329 c->data_size(), c->source_region(), c->destination_count());
330 ++full_region_count;
331 ++i;
332 }
333
334 size_t live_to_right = live_in_space - full_region_count * region_size;
335
336 double max_reclaimed_ratio = 0.0;
337 size_t max_reclaimed_ratio_region = 0;
338 size_t max_dead_to_right = 0;
339 size_t max_live_to_right = 0;
340
341 // Print the 'reclaimed ratio' for regions while there is something live in
342 // the region or to the right of it. The remaining regions are empty (and
343 // uninteresting), and computing the ratio will result in division by 0.
344 while (i < end_region && live_to_right > 0) {
345 c = summary_data.region(i);
346 HeapWord* const region_addr = summary_data.region_to_addr(i);
347 const size_t used_to_right = pointer_delta(space->top(), region_addr);
348 const size_t dead_to_right = used_to_right - live_to_right;
349 const double reclaimed_ratio = double(dead_to_right) / live_to_right;
350
351 if (reclaimed_ratio > max_reclaimed_ratio) {
352 max_reclaimed_ratio = reclaimed_ratio;
353 max_reclaimed_ratio_region = i;
354 max_dead_to_right = dead_to_right;
355 max_live_to_right = live_to_right;
356 }
357
358 ParallelCompactData::RegionData* c = summary_data.region(i);
359 log_develop_trace(gc, compaction)(
360 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d"
361 "%12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
362 i, p2i(c->destination()),
363 c->partial_obj_size(), c->live_obj_size(),
364 c->data_size(), c->source_region(), c->destination_count(),
365 reclaimed_ratio, dead_to_right, live_to_right);
366
367
368 live_to_right -= c->data_size();
369 ++i;
370 }
371
372 // Any remaining regions are empty. Print one more if there is one.
373 if (i < end_region) {
374 ParallelCompactData::RegionData* c = summary_data.region(i);
375 log_develop_trace(gc, compaction)(
376 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
377 i, p2i(c->destination()),
378 c->partial_obj_size(), c->live_obj_size(),
379 c->data_size(), c->source_region(), c->destination_count());
380 }
381
382 log_develop_trace(gc, compaction)("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
383 max_reclaimed_ratio_region, max_dead_to_right, max_live_to_right, max_reclaimed_ratio);
384 }
385
386 void
387 print_initial_summary_data(ParallelCompactData& summary_data,
388 SpaceInfo* space_info) {
389 if (!log_develop_is_enabled(Trace, gc, compaction)) {
390 return;
391 }
392
393 unsigned int id = PSParallelCompact::old_space_id;
394 const MutableSpace* space;
395 do {
396 space = space_info[id].space();
397 print_initial_summary_data(summary_data, space);
398 } while (++id < PSParallelCompact::eden_space_id);
399
400 do {
401 space = space_info[id].space();
402 print_generic_summary_data(summary_data, space->bottom(), space->top());
403 } while (++id < PSParallelCompact::last_space_id);
404 }
405 #endif // #ifndef PRODUCT
406
407 #ifdef ASSERT
408 size_t add_obj_count;
409 size_t add_obj_size;
410 size_t mark_bitmap_count;
411 size_t mark_bitmap_size;
412 #endif // #ifdef ASSERT
413
414 ParallelCompactData::ParallelCompactData() :
415 _region_start(NULL),
416 DEBUG_ONLY(_region_end(NULL) COMMA)
417 _region_vspace(NULL),
418 _reserved_byte_size(0),
419 _region_data(NULL),
420 _region_count(0),
421 _block_vspace(NULL),
422 _block_data(NULL),
423 _block_count(0) {}
424
425 bool ParallelCompactData::initialize(MemRegion covered_region)
426 {
427 _region_start = covered_region.start();
428 const size_t region_size = covered_region.word_size();
429 DEBUG_ONLY(_region_end = _region_start + region_size;)
430
431 assert(region_align_down(_region_start) == _region_start,
432 "region start not aligned");
433 assert((region_size & RegionSizeOffsetMask) == 0,
434 "region size not a multiple of RegionSize");
435
436 bool result = initialize_region_data(region_size) && initialize_block_data();
437 return result;
438 }
439
440 PSVirtualSpace*
441 ParallelCompactData::create_vspace(size_t count, size_t element_size)
442 {
443 const size_t raw_bytes = count * element_size;
444 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
445 const size_t granularity = os::vm_allocation_granularity();
446 _reserved_byte_size = align_up(raw_bytes, MAX2(page_sz, granularity));
447
448 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
449 MAX2(page_sz, granularity);
450 ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0);
451 os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, page_sz, rs.base(),
452 rs.size());
453
454 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
455
456 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
457 if (vspace != 0) {
458 if (vspace->expand_by(_reserved_byte_size)) {
459 return vspace;
460 }
461 delete vspace;
462 // Release memory reserved in the space.
463 rs.release();
464 }
465
466 return 0;
467 }
468
469 bool ParallelCompactData::initialize_region_data(size_t region_size)
470 {
471 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
472 _region_vspace = create_vspace(count, sizeof(RegionData));
473 if (_region_vspace != 0) {
474 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
475 _region_count = count;
476 return true;
477 }
478 return false;
479 }
480
481 bool ParallelCompactData::initialize_block_data()
482 {
483 assert(_region_count != 0, "region data must be initialized first");
484 const size_t count = _region_count << Log2BlocksPerRegion;
485 _block_vspace = create_vspace(count, sizeof(BlockData));
486 if (_block_vspace != 0) {
487 _block_data = (BlockData*)_block_vspace->reserved_low_addr();
488 _block_count = count;
489 return true;
490 }
491 return false;
492 }
493
494 void ParallelCompactData::clear()
495 {
496 memset(_region_data, 0, _region_vspace->committed_size());
497 memset(_block_data, 0, _block_vspace->committed_size());
498 }
499
500 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
501 assert(beg_region <= _region_count, "beg_region out of range");
502 assert(end_region <= _region_count, "end_region out of range");
503 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize");
504
505 const size_t region_cnt = end_region - beg_region;
506 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
507
508 const size_t beg_block = beg_region * BlocksPerRegion;
509 const size_t block_cnt = region_cnt * BlocksPerRegion;
510 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));
511 }
512
513 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
514 {
515 const RegionData* cur_cp = region(region_idx);
516 const RegionData* const end_cp = region(region_count() - 1);
517
518 HeapWord* result = region_to_addr(region_idx);
519 if (cur_cp < end_cp) {
520 do {
521 result += cur_cp->partial_obj_size();
522 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
523 }
524 return result;
525 }
526
527 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
528 {
529 const size_t obj_ofs = pointer_delta(addr, _region_start);
530 const size_t beg_region = obj_ofs >> Log2RegionSize;
531 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
532
533 DEBUG_ONLY(Atomic::inc(&add_obj_count);)
534 DEBUG_ONLY(Atomic::add(len, &add_obj_size);)
535
536 if (beg_region == end_region) {
537 // All in one region.
538 _region_data[beg_region].add_live_obj(len);
539 return;
540 }
541
542 // First region.
543 const size_t beg_ofs = region_offset(addr);
544 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
545
546 Klass* klass = ((oop)addr)->klass();
547 // Middle regions--completely spanned by this object.
548 for (size_t region = beg_region + 1; region < end_region; ++region) {
549 _region_data[region].set_partial_obj_size(RegionSize);
550 _region_data[region].set_partial_obj_addr(addr);
551 }
552
553 // Last region.
554 const size_t end_ofs = region_offset(addr + len - 1);
555 _region_data[end_region].set_partial_obj_size(end_ofs + 1);
556 _region_data[end_region].set_partial_obj_addr(addr);
557 }
558
559 void
560 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
561 {
562 assert(region_offset(beg) == 0, "not RegionSize aligned");
563 assert(region_offset(end) == 0, "not RegionSize aligned");
564
565 size_t cur_region = addr_to_region_idx(beg);
566 const size_t end_region = addr_to_region_idx(end);
567 HeapWord* addr = beg;
568 while (cur_region < end_region) {
569 _region_data[cur_region].set_destination(addr);
570 _region_data[cur_region].set_destination_count(0);
571 _region_data[cur_region].set_source_region(cur_region);
572 _region_data[cur_region].set_data_location(addr);
573
574 // Update live_obj_size so the region appears completely full.
575 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
576 _region_data[cur_region].set_live_obj_size(live_size);
577
578 ++cur_region;
579 addr += RegionSize;
580 }
581 }
582
583 // Find the point at which a space can be split and, if necessary, record the
584 // split point.
585 //
586 // If the current src region (which overflowed the destination space) doesn't
587 // have a partial object, the split point is at the beginning of the current src
588 // region (an "easy" split, no extra bookkeeping required).
589 //
590 // If the current src region has a partial object, the split point is in the
591 // region where that partial object starts (call it the split_region). If
592 // split_region has a partial object, then the split point is just after that
593 // partial object (a "hard" split where we have to record the split data and
594 // zero the partial_obj_size field). With a "hard" split, we know that the
595 // partial_obj ends within split_region because the partial object that caused
596 // the overflow starts in split_region. If split_region doesn't have a partial
597 // obj, then the split is at the beginning of split_region (another "easy"
598 // split).
599 HeapWord*
600 ParallelCompactData::summarize_split_space(size_t src_region,
601 SplitInfo& split_info,
602 HeapWord* destination,
603 HeapWord* target_end,
604 HeapWord** target_next)
605 {
606 assert(destination <= target_end, "sanity");
607 assert(destination + _region_data[src_region].data_size() > target_end,
608 "region should not fit into target space");
609 assert(is_region_aligned(target_end), "sanity");
610
611 size_t split_region = src_region;
612 HeapWord* split_destination = destination;
613 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
614
615 if (destination + partial_obj_size > target_end) {
616 // The split point is just after the partial object (if any) in the
617 // src_region that contains the start of the object that overflowed the
618 // destination space.
619 //
620 // Find the start of the "overflow" object and set split_region to the
621 // region containing it.
622 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
623 split_region = addr_to_region_idx(overflow_obj);
624
625 // Clear the source_region field of all destination regions whose first word
626 // came from data after the split point (a non-null source_region field
627 // implies a region must be filled).
628 //
629 // An alternative to the simple loop below: clear during post_compact(),
630 // which uses memcpy instead of individual stores, and is easy to
631 // parallelize. (The downside is that it clears the entire RegionData
632 // object as opposed to just one field.)
633 //
634 // post_compact() would have to clear the summary data up to the highest
635 // address that was written during the summary phase, which would be
636 //
637 // max(top, max(new_top, clear_top))
638 //
639 // where clear_top is a new field in SpaceInfo. Would have to set clear_top
640 // to target_end.
641 const RegionData* const sr = region(split_region);
642 const size_t beg_idx =
643 addr_to_region_idx(region_align_up(sr->destination() +
644 sr->partial_obj_size()));
645 const size_t end_idx = addr_to_region_idx(target_end);
646
647 log_develop_trace(gc, compaction)("split: clearing source_region field in [" SIZE_FORMAT ", " SIZE_FORMAT ")", beg_idx, end_idx);
648 for (size_t idx = beg_idx; idx < end_idx; ++idx) {
649 _region_data[idx].set_source_region(0);
650 }
651
652 // Set split_destination and partial_obj_size to reflect the split region.
653 split_destination = sr->destination();
654 partial_obj_size = sr->partial_obj_size();
655 }
656
657 // The split is recorded only if a partial object extends onto the region.
658 if (partial_obj_size != 0) {
659 _region_data[split_region].set_partial_obj_size(0);
660 split_info.record(split_region, partial_obj_size, split_destination);
661 }
662
663 // Setup the continuation addresses.
664 *target_next = split_destination + partial_obj_size;
665 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
666
667 if (log_develop_is_enabled(Trace, gc, compaction)) {
668 const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
669 log_develop_trace(gc, compaction)("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT " pos=" SIZE_FORMAT,
670 split_type, p2i(source_next), split_region, partial_obj_size);
671 log_develop_trace(gc, compaction)("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT " tn=" PTR_FORMAT,
672 split_type, p2i(split_destination),
673 addr_to_region_idx(split_destination),
674 p2i(*target_next));
675
676 if (partial_obj_size != 0) {
677 HeapWord* const po_beg = split_info.destination();
678 HeapWord* const po_end = po_beg + split_info.partial_obj_size();
679 log_develop_trace(gc, compaction)("%s split: po_beg=" PTR_FORMAT " " SIZE_FORMAT " po_end=" PTR_FORMAT " " SIZE_FORMAT,
680 split_type,
681 p2i(po_beg), addr_to_region_idx(po_beg),
682 p2i(po_end), addr_to_region_idx(po_end));
683 }
684 }
685
686 return source_next;
687 }
688
689 bool ParallelCompactData::summarize(SplitInfo& split_info,
690 HeapWord* source_beg, HeapWord* source_end,
691 HeapWord** source_next,
692 HeapWord* target_beg, HeapWord* target_end,
693 HeapWord** target_next)
694 {
695 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
696 log_develop_trace(gc, compaction)(
697 "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
698 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
699 p2i(source_beg), p2i(source_end), p2i(source_next_val),
700 p2i(target_beg), p2i(target_end), p2i(*target_next));
701
702 size_t cur_region = addr_to_region_idx(source_beg);
703 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
704
705 HeapWord *dest_addr = target_beg;
706 while (cur_region < end_region) {
707 // The destination must be set even if the region has no data.
708 _region_data[cur_region].set_destination(dest_addr);
709
710 size_t words = _region_data[cur_region].data_size();
711 if (words > 0) {
712 // If cur_region does not fit entirely into the target space, find a point
713 // at which the source space can be 'split' so that part is copied to the
714 // target space and the rest is copied elsewhere.
715 if (dest_addr + words > target_end) {
716 assert(source_next != NULL, "source_next is NULL when splitting");
717 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
718 target_end, target_next);
719 return false;
720 }
721
722 // Compute the destination_count for cur_region, and if necessary, update
723 // source_region for a destination region. The source_region field is
724 // updated if cur_region is the first (left-most) region to be copied to a
725 // destination region.
726 //
727 // The destination_count calculation is a bit subtle. A region that has
728 // data that compacts into itself does not count itself as a destination.
729 // This maintains the invariant that a zero count means the region is
730 // available and can be claimed and then filled.
731 uint destination_count = 0;
732 if (split_info.is_split(cur_region)) {
733 // The current region has been split: the partial object will be copied
734 // to one destination space and the remaining data will be copied to
735 // another destination space. Adjust the initial destination_count and,
736 // if necessary, set the source_region field if the partial object will
737 // cross a destination region boundary.
738 destination_count = split_info.destination_count();
739 if (destination_count == 2) {
740 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
741 _region_data[dest_idx].set_source_region(cur_region);
742 }
743 }
744
745 HeapWord* const last_addr = dest_addr + words - 1;
746 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
747 const size_t dest_region_2 = addr_to_region_idx(last_addr);
748
749 // Initially assume that the destination regions will be the same and
750 // adjust the value below if necessary. Under this assumption, if
751 // cur_region == dest_region_2, then cur_region will be compacted
752 // completely into itself.
753 destination_count += cur_region == dest_region_2 ? 0 : 1;
754 if (dest_region_1 != dest_region_2) {
755 // Destination regions differ; adjust destination_count.
756 destination_count += 1;
757 // Data from cur_region will be copied to the start of dest_region_2.
758 _region_data[dest_region_2].set_source_region(cur_region);
759 } else if (region_offset(dest_addr) == 0) {
760 // Data from cur_region will be copied to the start of the destination
761 // region.
762 _region_data[dest_region_1].set_source_region(cur_region);
763 }
764
765 _region_data[cur_region].set_destination_count(destination_count);
766 _region_data[cur_region].set_data_location(region_to_addr(cur_region));
767 dest_addr += words;
768 }
769
770 ++cur_region;
771 }
772
773 *target_next = dest_addr;
774 return true;
775 }
776
777 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr, ParCompactionManager* cm) {
778 assert(addr != NULL, "Should detect NULL oop earlier");
779 assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap");
780 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked");
781
782 // Region covering the object.
783 RegionData* const region_ptr = addr_to_region_ptr(addr);
784 HeapWord* result = region_ptr->destination();
785
786 // If the entire Region is live, the new location is region->destination + the
787 // offset of the object within in the Region.
788
789 // Run some performance tests to determine if this special case pays off. It
790 // is worth it for pointers into the dense prefix. If the optimization to
791 // avoid pointer updates in regions that only point to the dense prefix is
792 // ever implemented, this should be revisited.
793 if (region_ptr->data_size() == RegionSize) {
794 result += region_offset(addr);
795 return result;
796 }
797
798 // Otherwise, the new location is region->destination + block offset + the
799 // number of live words in the Block that are (a) to the left of addr and (b)
800 // due to objects that start in the Block.
801
802 // Fill in the block table if necessary. This is unsynchronized, so multiple
803 // threads may fill the block table for a region (harmless, since it is
804 // idempotent).
805 if (!region_ptr->blocks_filled()) {
806 PSParallelCompact::fill_blocks(addr_to_region_idx(addr));
807 region_ptr->set_blocks_filled();
808 }
809
810 HeapWord* const search_start = block_align_down(addr);
811 const size_t block_offset = addr_to_block_ptr(addr)->offset();
812
813 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
814 const size_t live = bitmap->live_words_in_range(cm, search_start, oop(addr));
815 result += block_offset + live;
816 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result));
817 return result;
818 }
819
820 #ifdef ASSERT
821 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
822 {
823 const size_t* const beg = (const size_t*)vspace->committed_low_addr();
824 const size_t* const end = (const size_t*)vspace->committed_high_addr();
825 for (const size_t* p = beg; p < end; ++p) {
826 assert(*p == 0, "not zero");
827 }
828 }
829
830 void ParallelCompactData::verify_clear()
831 {
832 verify_clear(_region_vspace);
833 verify_clear(_block_vspace);
834 }
835 #endif // #ifdef ASSERT
836
837 STWGCTimer PSParallelCompact::_gc_timer;
838 ParallelOldTracer PSParallelCompact::_gc_tracer;
839 elapsedTimer PSParallelCompact::_accumulated_time;
840 unsigned int PSParallelCompact::_total_invocations = 0;
841 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
842 jlong PSParallelCompact::_time_of_last_gc = 0;
843 CollectorCounters* PSParallelCompact::_counters = NULL;
844 ParMarkBitMap PSParallelCompact::_mark_bitmap;
845 ParallelCompactData PSParallelCompact::_summary_data;
846
847 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
848
849 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
850
851 class PCReferenceProcessor: public ReferenceProcessor {
852 public:
853 PCReferenceProcessor(
854 BoolObjectClosure* is_subject_to_discovery,
855 BoolObjectClosure* is_alive_non_header) :
856 ReferenceProcessor(is_subject_to_discovery,
857 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
858 ParallelGCThreads, // mt processing degree
859 true, // mt discovery
860 ParallelGCThreads, // mt discovery degree
861 true, // atomic_discovery
862 is_alive_non_header) {
863 }
864
865 template<typename T> bool discover(oop obj, ReferenceType type) {
866 T* referent_addr = (T*) java_lang_ref_Reference::referent_addr_raw(obj);
867 T heap_oop = RawAccess<>::oop_load(referent_addr);
868 oop referent = CompressedOops::decode_not_null(heap_oop);
869 return PSParallelCompact::mark_bitmap()->is_unmarked(referent)
870 && ReferenceProcessor::discover_reference(obj, type);
871 }
872 virtual bool discover_reference(oop obj, ReferenceType type) {
873 if (UseCompressedOops) {
874 return discover<narrowOop>(obj, type);
875 } else {
876 return discover<oop>(obj, type);
877 }
878 }
879 };
880
881 void PSParallelCompact::post_initialize() {
882 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
883 _span_based_discoverer.set_span(heap->reserved_region());
884 _ref_processor =
885 new PCReferenceProcessor(&_span_based_discoverer,
886 &_is_alive_closure); // non-header is alive closure
887
888 _counters = new CollectorCounters("Parallel full collection pauses", 1);
889
890 // Initialize static fields in ParCompactionManager.
891 ParCompactionManager::initialize(mark_bitmap());
892 }
893
894 bool PSParallelCompact::initialize() {
895 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
896 MemRegion mr = heap->reserved_region();
897
898 // Was the old gen get allocated successfully?
899 if (!heap->old_gen()->is_allocated()) {
900 return false;
901 }
902
903 initialize_space_info();
904 initialize_dead_wood_limiter();
905
906 if (!_mark_bitmap.initialize(mr)) {
907 vm_shutdown_during_initialization(
908 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
909 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
910 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
911 return false;
912 }
913
914 if (!_summary_data.initialize(mr)) {
915 vm_shutdown_during_initialization(
916 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
917 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
918 _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
919 return false;
920 }
921
922 return true;
923 }
924
925 void PSParallelCompact::initialize_space_info()
926 {
927 memset(&_space_info, 0, sizeof(_space_info));
928
929 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
930 PSYoungGen* young_gen = heap->young_gen();
931
932 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
933 _space_info[eden_space_id].set_space(young_gen->eden_space());
934 _space_info[from_space_id].set_space(young_gen->from_space());
935 _space_info[to_space_id].set_space(young_gen->to_space());
936
937 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
938 }
939
940 void PSParallelCompact::initialize_dead_wood_limiter()
941 {
942 const size_t max = 100;
943 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
944 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
945 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
946 DEBUG_ONLY(_dwl_initialized = true;)
947 _dwl_adjustment = normal_distribution(1.0);
948 }
949
950 void
951 PSParallelCompact::clear_data_covering_space(SpaceId id)
952 {
953 // At this point, top is the value before GC, new_top() is the value that will
954 // be set at the end of GC. The marking bitmap is cleared to top; nothing
955 // should be marked above top. The summary data is cleared to the larger of
956 // top & new_top.
957 MutableSpace* const space = _space_info[id].space();
958 HeapWord* const bot = space->bottom();
959 HeapWord* const top = space->top();
960 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
961
962 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
963 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
964 _mark_bitmap.clear_range(beg_bit, end_bit);
965
966 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
967 const size_t end_region =
968 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
969 _summary_data.clear_range(beg_region, end_region);
970
971 // Clear the data used to 'split' regions.
972 SplitInfo& split_info = _space_info[id].split_info();
973 if (split_info.is_valid()) {
974 split_info.clear();
975 }
976 DEBUG_ONLY(split_info.verify_clear();)
977 }
978
979 void PSParallelCompact::pre_compact()
980 {
981 // Update the from & to space pointers in space_info, since they are swapped
982 // at each young gen gc. Do the update unconditionally (even though a
983 // promotion failure does not swap spaces) because an unknown number of young
984 // collections will have swapped the spaces an unknown number of times.
985 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer);
986 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
987 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
988 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
989
990 DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
991 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
992
993 // Increment the invocation count
994 heap->increment_total_collections(true);
995
996 // We need to track unique mark sweep invocations as well.
997 _total_invocations++;
998
999 heap->print_heap_before_gc();
1000 heap->trace_heap_before_gc(&_gc_tracer);
1001
1002 // Fill in TLABs
1003 heap->ensure_parsability(true); // retire TLABs
1004
1005 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
1006 HandleMark hm; // Discard invalid handles created during verification
1007 Universe::verify("Before GC");
1008 }
1009
1010 // Verify object start arrays
1011 if (VerifyObjectStartArray &&
1012 VerifyBeforeGC) {
1013 heap->old_gen()->verify_object_start_array();
1014 }
1015
1016 DEBUG_ONLY(mark_bitmap()->verify_clear();)
1017 DEBUG_ONLY(summary_data().verify_clear();)
1018
1019 // Have worker threads release resources the next time they run a task.
1020 gc_task_manager()->release_all_resources();
1021
1022 ParCompactionManager::reset_all_bitmap_query_caches();
1023 }
1024
1025 void PSParallelCompact::post_compact()
1026 {
1027 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer);
1028
1029 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1030 // Clear the marking bitmap, summary data and split info.
1031 clear_data_covering_space(SpaceId(id));
1032 // Update top(). Must be done after clearing the bitmap and summary data.
1033 _space_info[id].publish_new_top();
1034 }
1035
1036 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1037 MutableSpace* const from_space = _space_info[from_space_id].space();
1038 MutableSpace* const to_space = _space_info[to_space_id].space();
1039
1040 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1041 bool eden_empty = eden_space->is_empty();
1042 if (!eden_empty) {
1043 eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1044 heap->young_gen(), heap->old_gen());
1045 }
1046
1047 // Update heap occupancy information which is used as input to the soft ref
1048 // clearing policy at the next gc.
1049 Universe::update_heap_info_at_gc();
1050
1051 bool young_gen_empty = eden_empty && from_space->is_empty() &&
1052 to_space->is_empty();
1053
1054 PSCardTable* ct = heap->card_table();
1055 MemRegion old_mr = heap->old_gen()->reserved();
1056 if (young_gen_empty) {
1057 ct->clear(MemRegion(old_mr.start(), old_mr.end()));
1058 } else {
1059 ct->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1060 }
1061
1062 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1063 ClassLoaderDataGraph::purge();
1064 DEBUG_ONLY(MetaspaceUtils::verify(false);)
1065
1066 heap->prune_scavengable_nmethods();
1067
1068 #if COMPILER2_OR_JVMCI
1069 DerivedPointerTable::update_pointers();
1070 #endif
1071
1072 if (ZapUnusedHeapArea) {
1073 heap->gen_mangle_unused_area();
1074 }
1075
1076 // Update time of last GC
1077 reset_millis_since_last_gc();
1078 }
1079
1080 HeapWord*
1081 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1082 bool maximum_compaction)
1083 {
1084 const size_t region_size = ParallelCompactData::RegionSize;
1085 const ParallelCompactData& sd = summary_data();
1086
1087 const MutableSpace* const space = _space_info[id].space();
1088 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1089 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1090 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1091
1092 // Skip full regions at the beginning of the space--they are necessarily part
1093 // of the dense prefix.
1094 size_t full_count = 0;
1095 const RegionData* cp;
1096 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1097 ++full_count;
1098 }
1099
1100 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1101 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1102 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1103 if (maximum_compaction || cp == end_cp || interval_ended) {
1104 _maximum_compaction_gc_num = total_invocations();
1105 return sd.region_to_addr(cp);
1106 }
1107
1108 HeapWord* const new_top = _space_info[id].new_top();
1109 const size_t space_live = pointer_delta(new_top, space->bottom());
1110 const size_t space_used = space->used_in_words();
1111 const size_t space_capacity = space->capacity_in_words();
1112
1113 const double cur_density = double(space_live) / space_capacity;
1114 const double deadwood_density =
1115 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1116 const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1117
1118 if (TraceParallelOldGCDensePrefix) {
1119 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1120 cur_density, deadwood_density, deadwood_goal);
1121 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1122 "space_cap=" SIZE_FORMAT,
1123 space_live, space_used,
1124 space_capacity);
1125 }
1126
1127 // XXX - Use binary search?
1128 HeapWord* dense_prefix = sd.region_to_addr(cp);
1129 const RegionData* full_cp = cp;
1130 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1131 while (cp < end_cp) {
1132 HeapWord* region_destination = cp->destination();
1133 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1134 if (TraceParallelOldGCDensePrefix && Verbose) {
1135 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1136 "dp=" PTR_FORMAT " " "cdw=" SIZE_FORMAT_W(8),
1137 sd.region(cp), p2i(region_destination),
1138 p2i(dense_prefix), cur_deadwood);
1139 }
1140
1141 if (cur_deadwood >= deadwood_goal) {
1142 // Found the region that has the correct amount of deadwood to the left.
1143 // This typically occurs after crossing a fairly sparse set of regions, so
1144 // iterate backwards over those sparse regions, looking for the region
1145 // that has the lowest density of live objects 'to the right.'
1146 size_t space_to_left = sd.region(cp) * region_size;
1147 size_t live_to_left = space_to_left - cur_deadwood;
1148 size_t space_to_right = space_capacity - space_to_left;
1149 size_t live_to_right = space_live - live_to_left;
1150 double density_to_right = double(live_to_right) / space_to_right;
1151 while (cp > full_cp) {
1152 --cp;
1153 const size_t prev_region_live_to_right = live_to_right -
1154 cp->data_size();
1155 const size_t prev_region_space_to_right = space_to_right + region_size;
1156 double prev_region_density_to_right =
1157 double(prev_region_live_to_right) / prev_region_space_to_right;
1158 if (density_to_right <= prev_region_density_to_right) {
1159 return dense_prefix;
1160 }
1161 if (TraceParallelOldGCDensePrefix && Verbose) {
1162 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1163 "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1164 prev_region_density_to_right);
1165 }
1166 dense_prefix -= region_size;
1167 live_to_right = prev_region_live_to_right;
1168 space_to_right = prev_region_space_to_right;
1169 density_to_right = prev_region_density_to_right;
1170 }
1171 return dense_prefix;
1172 }
1173
1174 dense_prefix += region_size;
1175 ++cp;
1176 }
1177
1178 return dense_prefix;
1179 }
1180
1181 #ifndef PRODUCT
1182 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1183 const SpaceId id,
1184 const bool maximum_compaction,
1185 HeapWord* const addr)
1186 {
1187 const size_t region_idx = summary_data().addr_to_region_idx(addr);
1188 RegionData* const cp = summary_data().region(region_idx);
1189 const MutableSpace* const space = _space_info[id].space();
1190 HeapWord* const new_top = _space_info[id].new_top();
1191
1192 const size_t space_live = pointer_delta(new_top, space->bottom());
1193 const size_t dead_to_left = pointer_delta(addr, cp->destination());
1194 const size_t space_cap = space->capacity_in_words();
1195 const double dead_to_left_pct = double(dead_to_left) / space_cap;
1196 const size_t live_to_right = new_top - cp->destination();
1197 const size_t dead_to_right = space->top() - addr - live_to_right;
1198
1199 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1200 "spl=" SIZE_FORMAT " "
1201 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1202 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1203 " ratio=%10.8f",
1204 algorithm, p2i(addr), region_idx,
1205 space_live,
1206 dead_to_left, dead_to_left_pct,
1207 dead_to_right, live_to_right,
1208 double(dead_to_right) / live_to_right);
1209 }
1210 #endif // #ifndef PRODUCT
1211
1212 // Return a fraction indicating how much of the generation can be treated as
1213 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution
1214 // based on the density of live objects in the generation to determine a limit,
1215 // which is then adjusted so the return value is min_percent when the density is
1216 // 1.
1217 //
1218 // The following table shows some return values for a different values of the
1219 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1220 // min_percent is 1.
1221 //
1222 // fraction allowed as dead wood
1223 // -----------------------------------------------------------------
1224 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1225 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1226 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1227 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1228 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1229 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1230 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1231 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1232 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1233 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1234 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1235 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1236 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1237 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1238 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1239 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1240 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1241 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1242 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1243 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1244 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1245 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1246 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1247
1248 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1249 {
1250 assert(_dwl_initialized, "uninitialized");
1251
1252 // The raw limit is the value of the normal distribution at x = density.
1253 const double raw_limit = normal_distribution(density);
1254
1255 // Adjust the raw limit so it becomes the minimum when the density is 1.
1256 //
1257 // First subtract the adjustment value (which is simply the precomputed value
1258 // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1259 // Then add the minimum value, so the minimum is returned when the density is
1260 // 1. Finally, prevent negative values, which occur when the mean is not 0.5.
1261 const double min = double(min_percent) / 100.0;
1262 const double limit = raw_limit - _dwl_adjustment + min;
1263 return MAX2(limit, 0.0);
1264 }
1265
1266 ParallelCompactData::RegionData*
1267 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1268 const RegionData* end)
1269 {
1270 const size_t region_size = ParallelCompactData::RegionSize;
1271 ParallelCompactData& sd = summary_data();
1272 size_t left = sd.region(beg);
1273 size_t right = end > beg ? sd.region(end) - 1 : left;
1274
1275 // Binary search.
1276 while (left < right) {
1277 // Equivalent to (left + right) / 2, but does not overflow.
1278 const size_t middle = left + (right - left) / 2;
1279 RegionData* const middle_ptr = sd.region(middle);
1280 HeapWord* const dest = middle_ptr->destination();
1281 HeapWord* const addr = sd.region_to_addr(middle);
1282 assert(dest != NULL, "sanity");
1283 assert(dest <= addr, "must move left");
1284
1285 if (middle > left && dest < addr) {
1286 right = middle - 1;
1287 } else if (middle < right && middle_ptr->data_size() == region_size) {
1288 left = middle + 1;
1289 } else {
1290 return middle_ptr;
1291 }
1292 }
1293 return sd.region(left);
1294 }
1295
1296 ParallelCompactData::RegionData*
1297 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1298 const RegionData* end,
1299 size_t dead_words)
1300 {
1301 ParallelCompactData& sd = summary_data();
1302 size_t left = sd.region(beg);
1303 size_t right = end > beg ? sd.region(end) - 1 : left;
1304
1305 // Binary search.
1306 while (left < right) {
1307 // Equivalent to (left + right) / 2, but does not overflow.
1308 const size_t middle = left + (right - left) / 2;
1309 RegionData* const middle_ptr = sd.region(middle);
1310 HeapWord* const dest = middle_ptr->destination();
1311 HeapWord* const addr = sd.region_to_addr(middle);
1312 assert(dest != NULL, "sanity");
1313 assert(dest <= addr, "must move left");
1314
1315 const size_t dead_to_left = pointer_delta(addr, dest);
1316 if (middle > left && dead_to_left > dead_words) {
1317 right = middle - 1;
1318 } else if (middle < right && dead_to_left < dead_words) {
1319 left = middle + 1;
1320 } else {
1321 return middle_ptr;
1322 }
1323 }
1324 return sd.region(left);
1325 }
1326
1327 // The result is valid during the summary phase, after the initial summarization
1328 // of each space into itself, and before final summarization.
1329 inline double
1330 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1331 HeapWord* const bottom,
1332 HeapWord* const top,
1333 HeapWord* const new_top)
1334 {
1335 ParallelCompactData& sd = summary_data();
1336
1337 assert(cp != NULL, "sanity");
1338 assert(bottom != NULL, "sanity");
1339 assert(top != NULL, "sanity");
1340 assert(new_top != NULL, "sanity");
1341 assert(top >= new_top, "summary data problem?");
1342 assert(new_top > bottom, "space is empty; should not be here");
1343 assert(new_top >= cp->destination(), "sanity");
1344 assert(top >= sd.region_to_addr(cp), "sanity");
1345
1346 HeapWord* const destination = cp->destination();
1347 const size_t dense_prefix_live = pointer_delta(destination, bottom);
1348 const size_t compacted_region_live = pointer_delta(new_top, destination);
1349 const size_t compacted_region_used = pointer_delta(top,
1350 sd.region_to_addr(cp));
1351 const size_t reclaimable = compacted_region_used - compacted_region_live;
1352
1353 const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1354 return double(reclaimable) / divisor;
1355 }
1356
1357 // Return the address of the end of the dense prefix, a.k.a. the start of the
1358 // compacted region. The address is always on a region boundary.
1359 //
1360 // Completely full regions at the left are skipped, since no compaction can
1361 // occur in those regions. Then the maximum amount of dead wood to allow is
1362 // computed, based on the density (amount live / capacity) of the generation;
1363 // the region with approximately that amount of dead space to the left is
1364 // identified as the limit region. Regions between the last completely full
1365 // region and the limit region are scanned and the one that has the best
1366 // (maximum) reclaimed_ratio() is selected.
1367 HeapWord*
1368 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1369 bool maximum_compaction)
1370 {
1371 const size_t region_size = ParallelCompactData::RegionSize;
1372 const ParallelCompactData& sd = summary_data();
1373
1374 const MutableSpace* const space = _space_info[id].space();
1375 HeapWord* const top = space->top();
1376 HeapWord* const top_aligned_up = sd.region_align_up(top);
1377 HeapWord* const new_top = _space_info[id].new_top();
1378 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1379 HeapWord* const bottom = space->bottom();
1380 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1381 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1382 const RegionData* const new_top_cp =
1383 sd.addr_to_region_ptr(new_top_aligned_up);
1384
1385 // Skip full regions at the beginning of the space--they are necessarily part
1386 // of the dense prefix.
1387 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1388 assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1389 space->is_empty(), "no dead space allowed to the left");
1390 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1391 "region must have dead space");
1392
1393 // The gc number is saved whenever a maximum compaction is done, and used to
1394 // determine when the maximum compaction interval has expired. This avoids
1395 // successive max compactions for different reasons.
1396 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1397 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1398 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1399 total_invocations() == HeapFirstMaximumCompactionCount;
1400 if (maximum_compaction || full_cp == top_cp || interval_ended) {
1401 _maximum_compaction_gc_num = total_invocations();
1402 return sd.region_to_addr(full_cp);
1403 }
1404
1405 const size_t space_live = pointer_delta(new_top, bottom);
1406 const size_t space_used = space->used_in_words();
1407 const size_t space_capacity = space->capacity_in_words();
1408
1409 const double density = double(space_live) / double(space_capacity);
1410 const size_t min_percent_free = MarkSweepDeadRatio;
1411 const double limiter = dead_wood_limiter(density, min_percent_free);
1412 const size_t dead_wood_max = space_used - space_live;
1413 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1414 dead_wood_max);
1415
1416 if (TraceParallelOldGCDensePrefix) {
1417 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1418 "space_cap=" SIZE_FORMAT,
1419 space_live, space_used,
1420 space_capacity);
1421 tty->print_cr("dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f "
1422 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1423 density, min_percent_free, limiter,
1424 dead_wood_max, dead_wood_limit);
1425 }
1426
1427 // Locate the region with the desired amount of dead space to the left.
1428 const RegionData* const limit_cp =
1429 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1430
1431 // Scan from the first region with dead space to the limit region and find the
1432 // one with the best (largest) reclaimed ratio.
1433 double best_ratio = 0.0;
1434 const RegionData* best_cp = full_cp;
1435 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1436 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1437 if (tmp_ratio > best_ratio) {
1438 best_cp = cp;
1439 best_ratio = tmp_ratio;
1440 }
1441 }
1442
1443 return sd.region_to_addr(best_cp);
1444 }
1445
1446 void PSParallelCompact::summarize_spaces_quick()
1447 {
1448 for (unsigned int i = 0; i < last_space_id; ++i) {
1449 const MutableSpace* space = _space_info[i].space();
1450 HeapWord** nta = _space_info[i].new_top_addr();
1451 bool result = _summary_data.summarize(_space_info[i].split_info(),
1452 space->bottom(), space->top(), NULL,
1453 space->bottom(), space->end(), nta);
1454 assert(result, "space must fit into itself");
1455 _space_info[i].set_dense_prefix(space->bottom());
1456 }
1457 }
1458
1459 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1460 {
1461 HeapWord* const dense_prefix_end = dense_prefix(id);
1462 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1463 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1464 if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1465 // Only enough dead space is filled so that any remaining dead space to the
1466 // left is larger than the minimum filler object. (The remainder is filled
1467 // during the copy/update phase.)
1468 //
1469 // The size of the dead space to the right of the boundary is not a
1470 // concern, since compaction will be able to use whatever space is
1471 // available.
1472 //
1473 // Here '||' is the boundary, 'x' represents a don't care bit and a box
1474 // surrounds the space to be filled with an object.
1475 //
1476 // In the 32-bit VM, each bit represents two 32-bit words:
1477 // +---+
1478 // a) beg_bits: ... x x x | 0 | || 0 x x ...
1479 // end_bits: ... x x x | 0 | || 0 x x ...
1480 // +---+
1481 //
1482 // In the 64-bit VM, each bit represents one 64-bit word:
1483 // +------------+
1484 // b) beg_bits: ... x x x | 0 || 0 | x x ...
1485 // end_bits: ... x x 1 | 0 || 0 | x x ...
1486 // +------------+
1487 // +-------+
1488 // c) beg_bits: ... x x | 0 0 | || 0 x x ...
1489 // end_bits: ... x 1 | 0 0 | || 0 x x ...
1490 // +-------+
1491 // +-----------+
1492 // d) beg_bits: ... x | 0 0 0 | || 0 x x ...
1493 // end_bits: ... 1 | 0 0 0 | || 0 x x ...
1494 // +-----------+
1495 // +-------+
1496 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ...
1497 // end_bits: ... 0 0 | 0 0 | || 0 x x ...
1498 // +-------+
1499
1500 // Initially assume case a, c or e will apply.
1501 size_t obj_len = CollectedHeap::min_fill_size();
1502 HeapWord* obj_beg = dense_prefix_end - obj_len;
1503
1504 #ifdef _LP64
1505 if (MinObjAlignment > 1) { // object alignment > heap word size
1506 // Cases a, c or e.
1507 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1508 // Case b above.
1509 obj_beg = dense_prefix_end - 1;
1510 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1511 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1512 // Case d above.
1513 obj_beg = dense_prefix_end - 3;
1514 obj_len = 3;
1515 }
1516 #endif // #ifdef _LP64
1517
1518 CollectedHeap::fill_with_object(obj_beg, obj_len);
1519 _mark_bitmap.mark_obj(obj_beg, obj_len);
1520 _summary_data.add_obj(obj_beg, obj_len);
1521 assert(start_array(id) != NULL, "sanity");
1522 start_array(id)->allocate_block(obj_beg);
1523 }
1524 }
1525
1526 void
1527 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1528 {
1529 assert(id < last_space_id, "id out of range");
1530 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(),
1531 "should have been reset in summarize_spaces_quick()");
1532
1533 const MutableSpace* space = _space_info[id].space();
1534 if (_space_info[id].new_top() != space->bottom()) {
1535 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1536 _space_info[id].set_dense_prefix(dense_prefix_end);
1537
1538 #ifndef PRODUCT
1539 if (TraceParallelOldGCDensePrefix) {
1540 print_dense_prefix_stats("ratio", id, maximum_compaction,
1541 dense_prefix_end);
1542 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1543 print_dense_prefix_stats("density", id, maximum_compaction, addr);
1544 }
1545 #endif // #ifndef PRODUCT
1546
1547 // Recompute the summary data, taking into account the dense prefix. If
1548 // every last byte will be reclaimed, then the existing summary data which
1549 // compacts everything can be left in place.
1550 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1551 // If dead space crosses the dense prefix boundary, it is (at least
1552 // partially) filled with a dummy object, marked live and added to the
1553 // summary data. This simplifies the copy/update phase and must be done
1554 // before the final locations of objects are determined, to prevent
1555 // leaving a fragment of dead space that is too small to fill.
1556 fill_dense_prefix_end(id);
1557
1558 // Compute the destination of each Region, and thus each object.
1559 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1560 _summary_data.summarize(_space_info[id].split_info(),
1561 dense_prefix_end, space->top(), NULL,
1562 dense_prefix_end, space->end(),
1563 _space_info[id].new_top_addr());
1564 }
1565 }
1566
1567 if (log_develop_is_enabled(Trace, gc, compaction)) {
1568 const size_t region_size = ParallelCompactData::RegionSize;
1569 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1570 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1571 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1572 HeapWord* const new_top = _space_info[id].new_top();
1573 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1574 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1575 log_develop_trace(gc, compaction)(
1576 "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1577 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1578 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1579 id, space->capacity_in_words(), p2i(dense_prefix_end),
1580 dp_region, dp_words / region_size,
1581 cr_words / region_size, p2i(new_top));
1582 }
1583 }
1584
1585 #ifndef PRODUCT
1586 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1587 HeapWord* dst_beg, HeapWord* dst_end,
1588 SpaceId src_space_id,
1589 HeapWord* src_beg, HeapWord* src_end)
1590 {
1591 log_develop_trace(gc, compaction)(
1592 "Summarizing %d [%s] into %d [%s]: "
1593 "src=" PTR_FORMAT "-" PTR_FORMAT " "
1594 SIZE_FORMAT "-" SIZE_FORMAT " "
1595 "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1596 SIZE_FORMAT "-" SIZE_FORMAT,
1597 src_space_id, space_names[src_space_id],
1598 dst_space_id, space_names[dst_space_id],
1599 p2i(src_beg), p2i(src_end),
1600 _summary_data.addr_to_region_idx(src_beg),
1601 _summary_data.addr_to_region_idx(src_end),
1602 p2i(dst_beg), p2i(dst_end),
1603 _summary_data.addr_to_region_idx(dst_beg),
1604 _summary_data.addr_to_region_idx(dst_end));
1605 }
1606 #endif // #ifndef PRODUCT
1607
1608 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1609 bool maximum_compaction)
1610 {
1611 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer);
1612
1613 #ifdef ASSERT
1614 if (TraceParallelOldGCMarkingPhase) {
1615 tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1616 "add_obj_bytes=" SIZE_FORMAT,
1617 add_obj_count, add_obj_size * HeapWordSize);
1618 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1619 "mark_bitmap_bytes=" SIZE_FORMAT,
1620 mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1621 }
1622 #endif // #ifdef ASSERT
1623
1624 // Quick summarization of each space into itself, to see how much is live.
1625 summarize_spaces_quick();
1626
1627 log_develop_trace(gc, compaction)("summary phase: after summarizing each space to self");
1628 NOT_PRODUCT(print_region_ranges());
1629 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1630
1631 // The amount of live data that will end up in old space (assuming it fits).
1632 size_t old_space_total_live = 0;
1633 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1634 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1635 _space_info[id].space()->bottom());
1636 }
1637
1638 MutableSpace* const old_space = _space_info[old_space_id].space();
1639 const size_t old_capacity = old_space->capacity_in_words();
1640 if (old_space_total_live > old_capacity) {
1641 // XXX - should also try to expand
1642 maximum_compaction = true;
1643 }
1644
1645 // Old generations.
1646 summarize_space(old_space_id, maximum_compaction);
1647
1648 // Summarize the remaining spaces in the young gen. The initial target space
1649 // is the old gen. If a space does not fit entirely into the target, then the
1650 // remainder is compacted into the space itself and that space becomes the new
1651 // target.
1652 SpaceId dst_space_id = old_space_id;
1653 HeapWord* dst_space_end = old_space->end();
1654 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1655 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1656 const MutableSpace* space = _space_info[id].space();
1657 const size_t live = pointer_delta(_space_info[id].new_top(),
1658 space->bottom());
1659 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1660
1661 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1662 SpaceId(id), space->bottom(), space->top());)
1663 if (live > 0 && live <= available) {
1664 // All the live data will fit.
1665 bool done = _summary_data.summarize(_space_info[id].split_info(),
1666 space->bottom(), space->top(),
1667 NULL,
1668 *new_top_addr, dst_space_end,
1669 new_top_addr);
1670 assert(done, "space must fit into old gen");
1671
1672 // Reset the new_top value for the space.
1673 _space_info[id].set_new_top(space->bottom());
1674 } else if (live > 0) {
1675 // Attempt to fit part of the source space into the target space.
1676 HeapWord* next_src_addr = NULL;
1677 bool done = _summary_data.summarize(_space_info[id].split_info(),
1678 space->bottom(), space->top(),
1679 &next_src_addr,
1680 *new_top_addr, dst_space_end,
1681 new_top_addr);
1682 assert(!done, "space should not fit into old gen");
1683 assert(next_src_addr != NULL, "sanity");
1684
1685 // The source space becomes the new target, so the remainder is compacted
1686 // within the space itself.
1687 dst_space_id = SpaceId(id);
1688 dst_space_end = space->end();
1689 new_top_addr = _space_info[id].new_top_addr();
1690 NOT_PRODUCT(summary_phase_msg(dst_space_id,
1691 space->bottom(), dst_space_end,
1692 SpaceId(id), next_src_addr, space->top());)
1693 done = _summary_data.summarize(_space_info[id].split_info(),
1694 next_src_addr, space->top(),
1695 NULL,
1696 space->bottom(), dst_space_end,
1697 new_top_addr);
1698 assert(done, "space must fit when compacted into itself");
1699 assert(*new_top_addr <= space->top(), "usage should not grow");
1700 }
1701 }
1702
1703 log_develop_trace(gc, compaction)("Summary_phase: after final summarization");
1704 NOT_PRODUCT(print_region_ranges());
1705 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1706 }
1707
1708 // This method should contain all heap-specific policy for invoking a full
1709 // collection. invoke_no_policy() will only attempt to compact the heap; it
1710 // will do nothing further. If we need to bail out for policy reasons, scavenge
1711 // before full gc, or any other specialized behavior, it needs to be added here.
1712 //
1713 // Note that this method should only be called from the vm_thread while at a
1714 // safepoint.
1715 //
1716 // Note that the all_soft_refs_clear flag in the soft ref policy
1717 // may be true because this method can be called without intervening
1718 // activity. For example when the heap space is tight and full measure
1719 // are being taken to free space.
1720 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1721 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1722 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1723 "should be in vm thread");
1724
1725 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1726 GCCause::Cause gc_cause = heap->gc_cause();
1727 assert(!heap->is_gc_active(), "not reentrant");
1728
1729 PSAdaptiveSizePolicy* policy = heap->size_policy();
1730 IsGCActiveMark mark;
1731
1732 if (ScavengeBeforeFullGC) {
1733 PSScavenge::invoke_no_policy();
1734 }
1735
1736 const bool clear_all_soft_refs =
1737 heap->soft_ref_policy()->should_clear_all_soft_refs();
1738
1739 PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1740 maximum_heap_compaction);
1741 }
1742
1743 // This method contains no policy. You should probably
1744 // be calling invoke() instead.
1745 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1746 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1747 assert(ref_processor() != NULL, "Sanity");
1748
1749 if (GCLocker::check_active_before_gc()) {
1750 return false;
1751 }
1752
1753 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1754
1755 GCIdMark gc_id_mark;
1756 _gc_timer.register_gc_start();
1757 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
1758
1759 TimeStamp marking_start;
1760 TimeStamp compaction_start;
1761 TimeStamp collection_exit;
1762
1763 GCCause::Cause gc_cause = heap->gc_cause();
1764 PSYoungGen* young_gen = heap->young_gen();
1765 PSOldGen* old_gen = heap->old_gen();
1766 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1767
1768 // The scope of casr should end after code that can change
1769 // SoftRefPolicy::_should_clear_all_soft_refs.
1770 ClearedAllSoftRefs casr(maximum_heap_compaction,
1771 heap->soft_ref_policy());
1772
1773 if (ZapUnusedHeapArea) {
1774 // Save information needed to minimize mangling
1775 heap->record_gen_tops_before_GC();
1776 }
1777
1778 // Make sure data structures are sane, make the heap parsable, and do other
1779 // miscellaneous bookkeeping.
1780 pre_compact();
1781
1782 const PreGCValues pre_gc_values(heap);
1783
1784 // Get the compaction manager reserved for the VM thread.
1785 ParCompactionManager* const vmthread_cm =
1786 ParCompactionManager::manager_array(gc_task_manager()->workers());
1787
1788 {
1789 ResourceMark rm;
1790 HandleMark hm;
1791
1792 // Set the number of GC threads to be used in this collection
1793 gc_task_manager()->set_active_gang();
1794 gc_task_manager()->task_idle_workers();
1795
1796 GCTraceCPUTime tcpu;
1797 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause, true);
1798
1799 heap->pre_full_gc_dump(&_gc_timer);
1800
1801 TraceCollectorStats tcs(counters());
1802 TraceMemoryManagerStats tms(heap->old_gc_manager(), gc_cause);
1803
1804 if (log_is_enabled(Debug, gc, heap, exit)) {
1805 accumulated_time()->start();
1806 }
1807
1808 // Let the size policy know we're starting
1809 size_policy->major_collection_begin();
1810
1811 #if COMPILER2_OR_JVMCI
1812 DerivedPointerTable::clear();
1813 #endif
1814
1815 ref_processor()->enable_discovery();
1816 ref_processor()->setup_policy(maximum_heap_compaction);
1817
1818 bool marked_for_unloading = false;
1819
1820 marking_start.update();
1821 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer);
1822
1823 bool max_on_system_gc = UseMaximumCompactionOnSystemGC
1824 && GCCause::is_user_requested_gc(gc_cause);
1825 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
1826
1827 #if COMPILER2_OR_JVMCI
1828 assert(DerivedPointerTable::is_active(), "Sanity");
1829 DerivedPointerTable::set_active(false);
1830 #endif
1831
1832 // adjust_roots() updates Universe::_intArrayKlassObj which is
1833 // needed by the compaction for filling holes in the dense prefix.
1834 adjust_roots(vmthread_cm);
1835
1836 compaction_start.update();
1837 compact();
1838
1839 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
1840 // done before resizing.
1841 post_compact();
1842
1843 // Let the size policy know we're done
1844 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
1845
1846 if (UseAdaptiveSizePolicy) {
1847 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
1848 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
1849 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
1850
1851 // Don't check if the size_policy is ready here. Let
1852 // the size_policy check that internally.
1853 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
1854 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
1855 // Swap the survivor spaces if from_space is empty. The
1856 // resize_young_gen() called below is normally used after
1857 // a successful young GC and swapping of survivor spaces;
1858 // otherwise, it will fail to resize the young gen with
1859 // the current implementation.
1860 if (young_gen->from_space()->is_empty()) {
1861 young_gen->from_space()->clear(SpaceDecorator::Mangle);
1862 young_gen->swap_spaces();
1863 }
1864
1865 // Calculate optimal free space amounts
1866 assert(young_gen->max_size() >
1867 young_gen->from_space()->capacity_in_bytes() +
1868 young_gen->to_space()->capacity_in_bytes(),
1869 "Sizes of space in young gen are out-of-bounds");
1870
1871 size_t young_live = young_gen->used_in_bytes();
1872 size_t eden_live = young_gen->eden_space()->used_in_bytes();
1873 size_t old_live = old_gen->used_in_bytes();
1874 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
1875 size_t max_old_gen_size = old_gen->max_gen_size();
1876 size_t max_eden_size = young_gen->max_size() -
1877 young_gen->from_space()->capacity_in_bytes() -
1878 young_gen->to_space()->capacity_in_bytes();
1879
1880 // Used for diagnostics
1881 size_policy->clear_generation_free_space_flags();
1882
1883 size_policy->compute_generations_free_space(young_live,
1884 eden_live,
1885 old_live,
1886 cur_eden,
1887 max_old_gen_size,
1888 max_eden_size,
1889 true /* full gc*/);
1890
1891 size_policy->check_gc_overhead_limit(eden_live,
1892 max_old_gen_size,
1893 max_eden_size,
1894 true /* full gc*/,
1895 gc_cause,
1896 heap->soft_ref_policy());
1897
1898 size_policy->decay_supplemental_growth(true /* full gc*/);
1899
1900 heap->resize_old_gen(
1901 size_policy->calculated_old_free_size_in_bytes());
1902
1903 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
1904 size_policy->calculated_survivor_size_in_bytes());
1905 }
1906
1907 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
1908 }
1909
1910 if (UsePerfData) {
1911 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
1912 counters->update_counters();
1913 counters->update_old_capacity(old_gen->capacity_in_bytes());
1914 counters->update_young_capacity(young_gen->capacity_in_bytes());
1915 }
1916
1917 heap->resize_all_tlabs();
1918
1919 // Resize the metaspace capacity after a collection
1920 MetaspaceGC::compute_new_size();
1921
1922 if (log_is_enabled(Debug, gc, heap, exit)) {
1923 accumulated_time()->stop();
1924 }
1925
1926 young_gen->print_used_change(pre_gc_values.young_gen_used());
1927 old_gen->print_used_change(pre_gc_values.old_gen_used());
1928 MetaspaceUtils::print_metaspace_change(pre_gc_values.metaspace_sizes());
1929
1930 // Track memory usage and detect low memory
1931 MemoryService::track_memory_usage();
1932 heap->update_counters();
1933 gc_task_manager()->release_idle_workers();
1934
1935 heap->post_full_gc_dump(&_gc_timer);
1936 }
1937
1938 #ifdef ASSERT
1939 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
1940 ParCompactionManager* const cm =
1941 ParCompactionManager::manager_array(int(i));
1942 assert(cm->marking_stack()->is_empty(), "should be empty");
1943 assert(cm->region_stack()->is_empty(), "Region stack " SIZE_FORMAT " is not empty", i);
1944 }
1945 #endif // ASSERT
1946
1947 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1948 HandleMark hm; // Discard invalid handles created during verification
1949 Universe::verify("After GC");
1950 }
1951
1952 // Re-verify object start arrays
1953 if (VerifyObjectStartArray &&
1954 VerifyAfterGC) {
1955 old_gen->verify_object_start_array();
1956 }
1957
1958 if (ZapUnusedHeapArea) {
1959 old_gen->object_space()->check_mangled_unused_area_complete();
1960 }
1961
1962 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1963
1964 collection_exit.update();
1965
1966 heap->print_heap_after_gc();
1967 heap->trace_heap_after_gc(&_gc_tracer);
1968
1969 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT,
1970 marking_start.ticks(), compaction_start.ticks(),
1971 collection_exit.ticks());
1972 gc_task_manager()->print_task_time_stamps();
1973
1974 #ifdef TRACESPINNING
1975 ParallelTaskTerminator::print_termination_counts();
1976 #endif
1977
1978 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
1979
1980 _gc_timer.register_gc_end();
1981
1982 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
1983 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
1984
1985 return true;
1986 }
1987
1988 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
1989 PSYoungGen* young_gen,
1990 PSOldGen* old_gen) {
1991 MutableSpace* const eden_space = young_gen->eden_space();
1992 assert(!eden_space->is_empty(), "eden must be non-empty");
1993 assert(young_gen->virtual_space()->alignment() ==
1994 old_gen->virtual_space()->alignment(), "alignments do not match");
1995
1996 // We also return false when it's a heterogenous heap because old generation cannot absorb data from eden
1997 // when it is allocated on different memory (example, nv-dimm) than young.
1998 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary) ||
1999 ParallelArguments::is_heterogeneous_heap()) {
2000 return false;
2001 }
2002
2003 // Both generations must be completely committed.
2004 if (young_gen->virtual_space()->uncommitted_size() != 0) {
2005 return false;
2006 }
2007 if (old_gen->virtual_space()->uncommitted_size() != 0) {
2008 return false;
2009 }
2010
2011 // Figure out how much to take from eden. Include the average amount promoted
2012 // in the total; otherwise the next young gen GC will simply bail out to a
2013 // full GC.
2014 const size_t alignment = old_gen->virtual_space()->alignment();
2015 const size_t eden_used = eden_space->used_in_bytes();
2016 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
2017 const size_t absorb_size = align_up(eden_used + promoted, alignment);
2018 const size_t eden_capacity = eden_space->capacity_in_bytes();
2019
2020 if (absorb_size >= eden_capacity) {
2021 return false; // Must leave some space in eden.
2022 }
2023
2024 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2025 if (new_young_size < young_gen->min_gen_size()) {
2026 return false; // Respect young gen minimum size.
2027 }
2028
2029 log_trace(gc, ergo, heap)(" absorbing " SIZE_FORMAT "K: "
2030 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2031 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2032 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2033 absorb_size / K,
2034 eden_capacity / K, (eden_capacity - absorb_size) / K,
2035 young_gen->from_space()->used_in_bytes() / K,
2036 young_gen->to_space()->used_in_bytes() / K,
2037 young_gen->capacity_in_bytes() / K, new_young_size / K);
2038
2039 // Fill the unused part of the old gen.
2040 MutableSpace* const old_space = old_gen->object_space();
2041 HeapWord* const unused_start = old_space->top();
2042 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2043
2044 if (unused_words > 0) {
2045 if (unused_words < CollectedHeap::min_fill_size()) {
2046 return false; // If the old gen cannot be filled, must give up.
2047 }
2048 CollectedHeap::fill_with_objects(unused_start, unused_words);
2049 }
2050
2051 // Take the live data from eden and set both top and end in the old gen to
2052 // eden top. (Need to set end because reset_after_change() mangles the region
2053 // from end to virtual_space->high() in debug builds).
2054 HeapWord* const new_top = eden_space->top();
2055 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2056 absorb_size);
2057 young_gen->reset_after_change();
2058 old_space->set_top(new_top);
2059 old_space->set_end(new_top);
2060 old_gen->reset_after_change();
2061
2062 // Update the object start array for the filler object and the data from eden.
2063 ObjectStartArray* const start_array = old_gen->start_array();
2064 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2065 start_array->allocate_block(p);
2066 }
2067
2068 // Could update the promoted average here, but it is not typically updated at
2069 // full GCs and the value to use is unclear. Something like
2070 //
2071 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2072
2073 size_policy->set_bytes_absorbed_from_eden(absorb_size);
2074 return true;
2075 }
2076
2077 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2078 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2079 "shouldn't return NULL");
2080 return ParallelScavengeHeap::gc_task_manager();
2081 }
2082
2083 class PCAddThreadRootsMarkingTaskClosure : public ThreadClosure {
2084 private:
2085 GCTaskQueue* _q;
2086
2087 public:
2088 PCAddThreadRootsMarkingTaskClosure(GCTaskQueue* q) : _q(q) { }
2089 void do_thread(Thread* t) {
2090 _q->enqueue(new ThreadRootsMarkingTask(t));
2091 }
2092 };
2093
2094 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2095 bool maximum_heap_compaction,
2096 ParallelOldTracer *gc_tracer) {
2097 // Recursively traverse all live objects and mark them
2098 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer);
2099
2100 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2101 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2102 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2103 TaskQueueSetSuper* qset = ParCompactionManager::stack_array();
2104 TaskTerminator terminator(active_gc_threads, qset);
2105
2106 PCMarkAndPushClosure mark_and_push_closure(cm);
2107 ParCompactionManager::FollowStackClosure follow_stack_closure(cm);
2108
2109 // Need new claim bits before marking starts.
2110 ClassLoaderDataGraph::clear_claimed_marks();
2111
2112 {
2113 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer);
2114
2115 ParallelScavengeHeap::ParStrongRootsScope psrs;
2116
2117 GCTaskQueue* q = GCTaskQueue::create();
2118
2119 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2120 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2121 // We scan the thread roots in parallel
2122 PCAddThreadRootsMarkingTaskClosure cl(q);
2123 Threads::java_threads_and_vm_thread_do(&cl);
2124 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2125 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2126 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2127 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data));
2128 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2129 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2130
2131 if (active_gc_threads > 1) {
2132 for (uint j = 0; j < active_gc_threads; j++) {
2133 q->enqueue(new StealMarkingTask(terminator.terminator()));
2134 }
2135 }
2136
2137 gc_task_manager()->execute_and_wait(q);
2138 }
2139
2140 // Process reference objects found during marking
2141 {
2142 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
2143
2144 ReferenceProcessorStats stats;
2145 ReferenceProcessorPhaseTimes pt(&_gc_timer, ref_processor()->max_num_queues());
2146
2147 if (ref_processor()->processing_is_mt()) {
2148 ref_processor()->set_active_mt_degree(active_gc_threads);
2149
2150 RefProcTaskExecutor task_executor;
2151 stats = ref_processor()->process_discovered_references(
2152 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2153 &task_executor, &pt);
2154 } else {
2155 stats = ref_processor()->process_discovered_references(
2156 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
2157 &pt);
2158 }
2159
2160 gc_tracer->report_gc_reference_stats(stats);
2161 pt.print_all_references();
2162 }
2163
2164 // This is the point where the entire marking should have completed.
2165 assert(cm->marking_stacks_empty(), "Marking should have completed");
2166
2167 {
2168 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer);
2169 WeakProcessor::weak_oops_do(is_alive_closure(), &do_nothing_cl);
2170 }
2171
2172 {
2173 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer);
2174
2175 // Follow system dictionary roots and unload classes.
2176 bool purged_class = SystemDictionary::do_unloading(&_gc_timer);
2177
2178 // Unload nmethods.
2179 CodeCache::do_unloading(is_alive_closure(), purged_class);
2180
2181 // Prune dead klasses from subklass/sibling/implementor lists.
2182 Klass::clean_weak_klass_links(purged_class);
2183
2184 // Clean JVMCI metadata handles.
2185 JVMCI_ONLY(JVMCI::do_unloading(purged_class));
2186 }
2187
2188 _gc_tracer.report_object_count_after_gc(is_alive_closure());
2189 }
2190
2191 void PSParallelCompact::adjust_roots(ParCompactionManager* cm) {
2192 // Adjust the pointers to reflect the new locations
2193 GCTraceTime(Info, gc, phases) tm("Adjust Roots", &_gc_timer);
2194
2195 // Need new claim bits when tracing through and adjusting pointers.
2196 ClassLoaderDataGraph::clear_claimed_marks();
2197
2198 PCAdjustPointerClosure oop_closure(cm);
2199
2200 // General strong roots.
2201 Universe::oops_do(&oop_closure);
2202 JNIHandles::oops_do(&oop_closure); // Global (strong) JNI handles
2203 Threads::oops_do(&oop_closure, NULL);
2204 ObjectSynchronizer::oops_do(&oop_closure);
2205 Management::oops_do(&oop_closure);
2206 JvmtiExport::oops_do(&oop_closure);
2207 SystemDictionary::oops_do(&oop_closure);
2208 CLDToOopClosure cld_closure(&oop_closure, ClassLoaderData::_claim_strong);
2209 ClassLoaderDataGraph::cld_do(&cld_closure);
2210
2211 // Now adjust pointers in remaining weak roots. (All of which should
2212 // have been cleared if they pointed to non-surviving objects.)
2213 WeakProcessor::oops_do(&oop_closure);
2214
2215 CodeBlobToOopClosure adjust_from_blobs(&oop_closure, CodeBlobToOopClosure::FixRelocations);
2216 CodeCache::blobs_do(&adjust_from_blobs);
2217 AOT_ONLY(AOTLoader::oops_do(&oop_closure);)
2218
2219 ref_processor()->weak_oops_do(&oop_closure);
2220 // Roots were visited so references into the young gen in roots
2221 // may have been scanned. Process them also.
2222 // Should the reference processor have a span that excludes
2223 // young gen objects?
2224 PSScavenge::reference_processor()->weak_oops_do(&oop_closure);
2225 }
2226
2227 // Helper class to print 8 region numbers per line and then print the total at the end.
2228 class FillableRegionLogger : public StackObj {
2229 private:
2230 Log(gc, compaction) log;
2231 static const int LineLength = 8;
2232 size_t _regions[LineLength];
2233 int _next_index;
2234 bool _enabled;
2235 size_t _total_regions;
2236 public:
2237 FillableRegionLogger() : _next_index(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)), _total_regions(0) { }
2238 ~FillableRegionLogger() {
2239 log.trace(SIZE_FORMAT " initially fillable regions", _total_regions);
2240 }
2241
2242 void print_line() {
2243 if (!_enabled || _next_index == 0) {
2244 return;
2245 }
2246 FormatBuffer<> line("Fillable: ");
2247 for (int i = 0; i < _next_index; i++) {
2248 line.append(" " SIZE_FORMAT_W(7), _regions[i]);
2249 }
2250 log.trace("%s", line.buffer());
2251 _next_index = 0;
2252 }
2253
2254 void handle(size_t region) {
2255 if (!_enabled) {
2256 return;
2257 }
2258 _regions[_next_index++] = region;
2259 if (_next_index == LineLength) {
2260 print_line();
2261 }
2262 _total_regions++;
2263 }
2264 };
2265
2266 void PSParallelCompact::prepare_region_draining_tasks(GCTaskQueue* q,
2267 uint parallel_gc_threads)
2268 {
2269 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer);
2270
2271 // Find the threads that are active
2272 unsigned int which = 0;
2273
2274 // Find all regions that are available (can be filled immediately) and
2275 // distribute them to the thread stacks. The iteration is done in reverse
2276 // order (high to low) so the regions will be removed in ascending order.
2277
2278 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2279
2280 which = 0;
2281 // id + 1 is used to test termination so unsigned can
2282 // be used with an old_space_id == 0.
2283 FillableRegionLogger region_logger;
2284 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2285 SpaceInfo* const space_info = _space_info + id;
2286 MutableSpace* const space = space_info->space();
2287 HeapWord* const new_top = space_info->new_top();
2288
2289 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2290 const size_t end_region =
2291 sd.addr_to_region_idx(sd.region_align_up(new_top));
2292
2293 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2294 if (sd.region(cur)->claim_unsafe()) {
2295 ParCompactionManager* cm = ParCompactionManager::manager_array(which);
2296 cm->region_stack()->push(cur);
2297 region_logger.handle(cur);
2298 // Assign regions to tasks in round-robin fashion.
2299 if (++which == parallel_gc_threads) {
2300 which = 0;
2301 }
2302 }
2303 }
2304 region_logger.print_line();
2305 }
2306 }
2307
2308 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2309
2310 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2311 uint parallel_gc_threads) {
2312 GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer);
2313
2314 ParallelCompactData& sd = PSParallelCompact::summary_data();
2315
2316 // Iterate over all the spaces adding tasks for updating
2317 // regions in the dense prefix. Assume that 1 gc thread
2318 // will work on opening the gaps and the remaining gc threads
2319 // will work on the dense prefix.
2320 unsigned int space_id;
2321 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2322 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2323 const MutableSpace* const space = _space_info[space_id].space();
2324
2325 if (dense_prefix_end == space->bottom()) {
2326 // There is no dense prefix for this space.
2327 continue;
2328 }
2329
2330 // The dense prefix is before this region.
2331 size_t region_index_end_dense_prefix =
2332 sd.addr_to_region_idx(dense_prefix_end);
2333 RegionData* const dense_prefix_cp =
2334 sd.region(region_index_end_dense_prefix);
2335 assert(dense_prefix_end == space->end() ||
2336 dense_prefix_cp->available() ||
2337 dense_prefix_cp->claimed(),
2338 "The region after the dense prefix should always be ready to fill");
2339
2340 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2341
2342 // Is there dense prefix work?
2343 size_t total_dense_prefix_regions =
2344 region_index_end_dense_prefix - region_index_start;
2345 // How many regions of the dense prefix should be given to
2346 // each thread?
2347 if (total_dense_prefix_regions > 0) {
2348 uint tasks_for_dense_prefix = 1;
2349 if (total_dense_prefix_regions <=
2350 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2351 // Don't over partition. This assumes that
2352 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2353 // so there are not many regions to process.
2354 tasks_for_dense_prefix = parallel_gc_threads;
2355 } else {
2356 // Over partition
2357 tasks_for_dense_prefix = parallel_gc_threads *
2358 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2359 }
2360 size_t regions_per_thread = total_dense_prefix_regions /
2361 tasks_for_dense_prefix;
2362 // Give each thread at least 1 region.
2363 if (regions_per_thread == 0) {
2364 regions_per_thread = 1;
2365 }
2366
2367 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2368 if (region_index_start >= region_index_end_dense_prefix) {
2369 break;
2370 }
2371 // region_index_end is not processed
2372 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2373 region_index_end_dense_prefix);
2374 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2375 region_index_start,
2376 region_index_end));
2377 region_index_start = region_index_end;
2378 }
2379 }
2380 // This gets any part of the dense prefix that did not
2381 // fit evenly.
2382 if (region_index_start < region_index_end_dense_prefix) {
2383 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2384 region_index_start,
2385 region_index_end_dense_prefix));
2386 }
2387 }
2388 }
2389
2390 void PSParallelCompact::enqueue_region_stealing_tasks(
2391 GCTaskQueue* q,
2392 ParallelTaskTerminator* terminator_ptr,
2393 uint parallel_gc_threads) {
2394 GCTraceTime(Trace, gc, phases) tm("Steal Task Setup", &_gc_timer);
2395
2396 // Once a thread has drained it's stack, it should try to steal regions from
2397 // other threads.
2398 for (uint j = 0; j < parallel_gc_threads; j++) {
2399 q->enqueue(new CompactionWithStealingTask(terminator_ptr));
2400 }
2401 }
2402
2403 #ifdef ASSERT
2404 // Write a histogram of the number of times the block table was filled for a
2405 // region.
2406 void PSParallelCompact::write_block_fill_histogram()
2407 {
2408 if (!log_develop_is_enabled(Trace, gc, compaction)) {
2409 return;
2410 }
2411
2412 Log(gc, compaction) log;
2413 ResourceMark rm;
2414 LogStream ls(log.trace());
2415 outputStream* out = &ls;
2416
2417 typedef ParallelCompactData::RegionData rd_t;
2418 ParallelCompactData& sd = summary_data();
2419
2420 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2421 MutableSpace* const spc = _space_info[id].space();
2422 if (spc->bottom() != spc->top()) {
2423 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
2424 HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
2425 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
2426
2427 size_t histo[5] = { 0, 0, 0, 0, 0 };
2428 const size_t histo_len = sizeof(histo) / sizeof(size_t);
2429 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
2430
2431 for (const rd_t* cur = beg; cur < end; ++cur) {
2432 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
2433 }
2434 out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
2435 for (size_t i = 0; i < histo_len; ++i) {
2436 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
2437 histo[i], 100.0 * histo[i] / region_cnt);
2438 }
2439 out->cr();
2440 }
2441 }
2442 }
2443 #endif // #ifdef ASSERT
2444
2445 void PSParallelCompact::compact() {
2446 GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer);
2447
2448 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2449 PSOldGen* old_gen = heap->old_gen();
2450 old_gen->start_array()->reset();
2451 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2452 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2453 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2454 TaskTerminator terminator(active_gc_threads, qset);
2455
2456 GCTaskQueue* q = GCTaskQueue::create();
2457 prepare_region_draining_tasks(q, active_gc_threads);
2458 enqueue_dense_prefix_tasks(q, active_gc_threads);
2459 enqueue_region_stealing_tasks(q, terminator.terminator(), active_gc_threads);
2460
2461 {
2462 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer);
2463
2464 gc_task_manager()->execute_and_wait(q);
2465
2466 #ifdef ASSERT
2467 // Verify that all regions have been processed before the deferred updates.
2468 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2469 verify_complete(SpaceId(id));
2470 }
2471 #endif
2472 }
2473
2474 {
2475 // Update the deferred objects, if any. Any compaction manager can be used.
2476 GCTraceTime(Trace, gc, phases) tm("Deferred Updates", &_gc_timer);
2477 ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2478 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2479 update_deferred_objects(cm, SpaceId(id));
2480 }
2481 }
2482
2483 DEBUG_ONLY(write_block_fill_histogram());
2484 }
2485
2486 #ifdef ASSERT
2487 void PSParallelCompact::verify_complete(SpaceId space_id) {
2488 // All Regions between space bottom() to new_top() should be marked as filled
2489 // and all Regions between new_top() and top() should be available (i.e.,
2490 // should have been emptied).
2491 ParallelCompactData& sd = summary_data();
2492 SpaceInfo si = _space_info[space_id];
2493 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2494 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2495 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2496 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2497 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2498
2499 bool issued_a_warning = false;
2500
2501 size_t cur_region;
2502 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2503 const RegionData* const c = sd.region(cur_region);
2504 if (!c->completed()) {
2505 log_warning(gc)("region " SIZE_FORMAT " not filled: destination_count=%u",
2506 cur_region, c->destination_count());
2507 issued_a_warning = true;
2508 }
2509 }
2510
2511 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2512 const RegionData* const c = sd.region(cur_region);
2513 if (!c->available()) {
2514 log_warning(gc)("region " SIZE_FORMAT " not empty: destination_count=%u",
2515 cur_region, c->destination_count());
2516 issued_a_warning = true;
2517 }
2518 }
2519
2520 if (issued_a_warning) {
2521 print_region_ranges();
2522 }
2523 }
2524 #endif // #ifdef ASSERT
2525
2526 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) {
2527 _start_array->allocate_block(addr);
2528 compaction_manager()->update_contents(oop(addr));
2529 }
2530
2531 // Update interior oops in the ranges of regions [beg_region, end_region).
2532 void
2533 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2534 SpaceId space_id,
2535 size_t beg_region,
2536 size_t end_region) {
2537 ParallelCompactData& sd = summary_data();
2538 ParMarkBitMap* const mbm = mark_bitmap();
2539
2540 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2541 HeapWord* const end_addr = sd.region_to_addr(end_region);
2542 assert(beg_region <= end_region, "bad region range");
2543 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2544
2545 #ifdef ASSERT
2546 // Claim the regions to avoid triggering an assert when they are marked as
2547 // filled.
2548 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2549 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2550 }
2551 #endif // #ifdef ASSERT
2552
2553 if (beg_addr != space(space_id)->bottom()) {
2554 // Find the first live object or block of dead space that *starts* in this
2555 // range of regions. If a partial object crosses onto the region, skip it;
2556 // it will be marked for 'deferred update' when the object head is
2557 // processed. If dead space crosses onto the region, it is also skipped; it
2558 // will be filled when the prior region is processed. If neither of those
2559 // apply, the first word in the region is the start of a live object or dead
2560 // space.
2561 assert(beg_addr > space(space_id)->bottom(), "sanity");
2562 const RegionData* const cp = sd.region(beg_region);
2563 if (cp->partial_obj_size() != 0) {
2564 beg_addr = sd.partial_obj_end(beg_region);
2565 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2566 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2567 }
2568 }
2569
2570 if (beg_addr < end_addr) {
2571 // A live object or block of dead space starts in this range of Regions.
2572 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2573
2574 // Create closures and iterate.
2575 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2576 FillClosure fill_closure(cm, space_id);
2577 ParMarkBitMap::IterationStatus status;
2578 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2579 dense_prefix_end);
2580 if (status == ParMarkBitMap::incomplete) {
2581 update_closure.do_addr(update_closure.source());
2582 }
2583 }
2584
2585 // Mark the regions as filled.
2586 RegionData* const beg_cp = sd.region(beg_region);
2587 RegionData* const end_cp = sd.region(end_region);
2588 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2589 cp->set_completed();
2590 }
2591 }
2592
2593 // Return the SpaceId for the space containing addr. If addr is not in the
2594 // heap, last_space_id is returned. In debug mode it expects the address to be
2595 // in the heap and asserts such.
2596 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2597 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
2598
2599 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2600 if (_space_info[id].space()->contains(addr)) {
2601 return SpaceId(id);
2602 }
2603 }
2604
2605 assert(false, "no space contains the addr");
2606 return last_space_id;
2607 }
2608
2609 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2610 SpaceId id) {
2611 assert(id < last_space_id, "bad space id");
2612
2613 ParallelCompactData& sd = summary_data();
2614 const SpaceInfo* const space_info = _space_info + id;
2615 ObjectStartArray* const start_array = space_info->start_array();
2616
2617 const MutableSpace* const space = space_info->space();
2618 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2619 HeapWord* const beg_addr = space_info->dense_prefix();
2620 HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2621
2622 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2623 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2624 const RegionData* cur_region;
2625 for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2626 HeapWord* const addr = cur_region->deferred_obj_addr();
2627 if (addr != NULL) {
2628 if (start_array != NULL) {
2629 start_array->allocate_block(addr);
2630 }
2631 cm->update_contents(oop(addr));
2632 assert(oopDesc::is_oop_or_null(oop(addr)), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(addr)));
2633 }
2634 }
2635 }
2636
2637 // Skip over count live words starting from beg, and return the address of the
2638 // next live word. Unless marked, the word corresponding to beg is assumed to
2639 // be dead. Callers must either ensure beg does not correspond to the middle of
2640 // an object, or account for those live words in some other way. Callers must
2641 // also ensure that there are enough live words in the range [beg, end) to skip.
2642 HeapWord*
2643 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2644 {
2645 assert(count > 0, "sanity");
2646
2647 ParMarkBitMap* m = mark_bitmap();
2648 idx_t bits_to_skip = m->words_to_bits(count);
2649 idx_t cur_beg = m->addr_to_bit(beg);
2650 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
2651
2652 do {
2653 cur_beg = m->find_obj_beg(cur_beg, search_end);
2654 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2655 const size_t obj_bits = cur_end - cur_beg + 1;
2656 if (obj_bits > bits_to_skip) {
2657 return m->bit_to_addr(cur_beg + bits_to_skip);
2658 }
2659 bits_to_skip -= obj_bits;
2660 cur_beg = cur_end + 1;
2661 } while (bits_to_skip > 0);
2662
2663 // Skipping the desired number of words landed just past the end of an object.
2664 // Find the start of the next object.
2665 cur_beg = m->find_obj_beg(cur_beg, search_end);
2666 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2667 return m->bit_to_addr(cur_beg);
2668 }
2669
2670 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2671 SpaceId src_space_id,
2672 size_t src_region_idx)
2673 {
2674 assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2675
2676 const SplitInfo& split_info = _space_info[src_space_id].split_info();
2677 if (split_info.dest_region_addr() == dest_addr) {
2678 // The partial object ending at the split point contains the first word to
2679 // be copied to dest_addr.
2680 return split_info.first_src_addr();
2681 }
2682
2683 const ParallelCompactData& sd = summary_data();
2684 ParMarkBitMap* const bitmap = mark_bitmap();
2685 const size_t RegionSize = ParallelCompactData::RegionSize;
2686
2687 assert(sd.is_region_aligned(dest_addr), "not aligned");
2688 const RegionData* const src_region_ptr = sd.region(src_region_idx);
2689 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2690 HeapWord* const src_region_destination = src_region_ptr->destination();
2691
2692 assert(dest_addr >= src_region_destination, "wrong src region");
2693 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2694
2695 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2696 HeapWord* const src_region_end = src_region_beg + RegionSize;
2697
2698 HeapWord* addr = src_region_beg;
2699 if (dest_addr == src_region_destination) {
2700 // Return the first live word in the source region.
2701 if (partial_obj_size == 0) {
2702 addr = bitmap->find_obj_beg(addr, src_region_end);
2703 assert(addr < src_region_end, "no objects start in src region");
2704 }
2705 return addr;
2706 }
2707
2708 // Must skip some live data.
2709 size_t words_to_skip = dest_addr - src_region_destination;
2710 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2711
2712 if (partial_obj_size >= words_to_skip) {
2713 // All the live words to skip are part of the partial object.
2714 addr += words_to_skip;
2715 if (partial_obj_size == words_to_skip) {
2716 // Find the first live word past the partial object.
2717 addr = bitmap->find_obj_beg(addr, src_region_end);
2718 assert(addr < src_region_end, "wrong src region");
2719 }
2720 return addr;
2721 }
2722
2723 // Skip over the partial object (if any).
2724 if (partial_obj_size != 0) {
2725 words_to_skip -= partial_obj_size;
2726 addr += partial_obj_size;
2727 }
2728
2729 // Skip over live words due to objects that start in the region.
2730 addr = skip_live_words(addr, src_region_end, words_to_skip);
2731 assert(addr < src_region_end, "wrong src region");
2732 return addr;
2733 }
2734
2735 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2736 SpaceId src_space_id,
2737 size_t beg_region,
2738 HeapWord* end_addr)
2739 {
2740 ParallelCompactData& sd = summary_data();
2741
2742 #ifdef ASSERT
2743 MutableSpace* const src_space = _space_info[src_space_id].space();
2744 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2745 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2746 "src_space_id does not match beg_addr");
2747 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2748 "src_space_id does not match end_addr");
2749 #endif // #ifdef ASSERT
2750
2751 RegionData* const beg = sd.region(beg_region);
2752 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2753
2754 // Regions up to new_top() are enqueued if they become available.
2755 HeapWord* const new_top = _space_info[src_space_id].new_top();
2756 RegionData* const enqueue_end =
2757 sd.addr_to_region_ptr(sd.region_align_up(new_top));
2758
2759 for (RegionData* cur = beg; cur < end; ++cur) {
2760 assert(cur->data_size() > 0, "region must have live data");
2761 cur->decrement_destination_count();
2762 if (cur < enqueue_end && cur->available() && cur->claim()) {
2763 cm->push_region(sd.region(cur));
2764 }
2765 }
2766 }
2767
2768 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2769 SpaceId& src_space_id,
2770 HeapWord*& src_space_top,
2771 HeapWord* end_addr)
2772 {
2773 typedef ParallelCompactData::RegionData RegionData;
2774
2775 ParallelCompactData& sd = PSParallelCompact::summary_data();
2776 const size_t region_size = ParallelCompactData::RegionSize;
2777
2778 size_t src_region_idx = 0;
2779
2780 // Skip empty regions (if any) up to the top of the space.
2781 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2782 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2783 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2784 const RegionData* const top_region_ptr =
2785 sd.addr_to_region_ptr(top_aligned_up);
2786 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2787 ++src_region_ptr;
2788 }
2789
2790 if (src_region_ptr < top_region_ptr) {
2791 // The next source region is in the current space. Update src_region_idx
2792 // and the source address to match src_region_ptr.
2793 src_region_idx = sd.region(src_region_ptr);
2794 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
2795 if (src_region_addr > closure.source()) {
2796 closure.set_source(src_region_addr);
2797 }
2798 return src_region_idx;
2799 }
2800
2801 // Switch to a new source space and find the first non-empty region.
2802 unsigned int space_id = src_space_id + 1;
2803 assert(space_id < last_space_id, "not enough spaces");
2804
2805 HeapWord* const destination = closure.destination();
2806
2807 do {
2808 MutableSpace* space = _space_info[space_id].space();
2809 HeapWord* const bottom = space->bottom();
2810 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
2811
2812 // Iterate over the spaces that do not compact into themselves.
2813 if (bottom_cp->destination() != bottom) {
2814 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
2815 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
2816
2817 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
2818 if (src_cp->live_obj_size() > 0) {
2819 // Found it.
2820 assert(src_cp->destination() == destination,
2821 "first live obj in the space must match the destination");
2822 assert(src_cp->partial_obj_size() == 0,
2823 "a space cannot begin with a partial obj");
2824
2825 src_space_id = SpaceId(space_id);
2826 src_space_top = space->top();
2827 const size_t src_region_idx = sd.region(src_cp);
2828 closure.set_source(sd.region_to_addr(src_region_idx));
2829 return src_region_idx;
2830 } else {
2831 assert(src_cp->data_size() == 0, "sanity");
2832 }
2833 }
2834 }
2835 } while (++space_id < last_space_id);
2836
2837 assert(false, "no source region was found");
2838 return 0;
2839 }
2840
2841 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
2842 {
2843 typedef ParMarkBitMap::IterationStatus IterationStatus;
2844 const size_t RegionSize = ParallelCompactData::RegionSize;
2845 ParMarkBitMap* const bitmap = mark_bitmap();
2846 ParallelCompactData& sd = summary_data();
2847 RegionData* const region_ptr = sd.region(region_idx);
2848
2849 // Get the items needed to construct the closure.
2850 HeapWord* dest_addr = sd.region_to_addr(region_idx);
2851 SpaceId dest_space_id = space_id(dest_addr);
2852 ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
2853 HeapWord* new_top = _space_info[dest_space_id].new_top();
2854 assert(dest_addr < new_top, "sanity");
2855 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
2856
2857 // Get the source region and related info.
2858 size_t src_region_idx = region_ptr->source_region();
2859 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2860 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2861
2862 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
2863 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2864
2865 // Adjust src_region_idx to prepare for decrementing destination counts (the
2866 // destination count is not decremented when a region is copied to itself).
2867 if (src_region_idx == region_idx) {
2868 src_region_idx += 1;
2869 }
2870
2871 if (bitmap->is_unmarked(closure.source())) {
2872 // The first source word is in the middle of an object; copy the remainder
2873 // of the object or as much as will fit. The fact that pointer updates were
2874 // deferred will be noted when the object header is processed.
2875 HeapWord* const old_src_addr = closure.source();
2876 closure.copy_partial_obj();
2877 if (closure.is_full()) {
2878 decrement_destination_counts(cm, src_space_id, src_region_idx,
2879 closure.source());
2880 region_ptr->set_deferred_obj_addr(NULL);
2881 region_ptr->set_completed();
2882 return;
2883 }
2884
2885 HeapWord* const end_addr = sd.region_align_down(closure.source());
2886 if (sd.region_align_down(old_src_addr) != end_addr) {
2887 // The partial object was copied from more than one source region.
2888 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2889
2890 // Move to the next source region, possibly switching spaces as well. All
2891 // args except end_addr may be modified.
2892 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2893 end_addr);
2894 }
2895 }
2896
2897 do {
2898 HeapWord* const cur_addr = closure.source();
2899 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2900 src_space_top);
2901 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
2902
2903 if (status == ParMarkBitMap::incomplete) {
2904 // The last obj that starts in the source region does not end in the
2905 // region.
2906 assert(closure.source() < end_addr, "sanity");
2907 HeapWord* const obj_beg = closure.source();
2908 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
2909 src_space_top);
2910 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
2911 if (obj_end < range_end) {
2912 // The end was found; the entire object will fit.
2913 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
2914 assert(status != ParMarkBitMap::would_overflow, "sanity");
2915 } else {
2916 // The end was not found; the object will not fit.
2917 assert(range_end < src_space_top, "obj cannot cross space boundary");
2918 status = ParMarkBitMap::would_overflow;
2919 }
2920 }
2921
2922 if (status == ParMarkBitMap::would_overflow) {
2923 // The last object did not fit. Note that interior oop updates were
2924 // deferred, then copy enough of the object to fill the region.
2925 region_ptr->set_deferred_obj_addr(closure.destination());
2926 status = closure.copy_until_full(); // copies from closure.source()
2927
2928 decrement_destination_counts(cm, src_space_id, src_region_idx,
2929 closure.source());
2930 region_ptr->set_completed();
2931 return;
2932 }
2933
2934 if (status == ParMarkBitMap::full) {
2935 decrement_destination_counts(cm, src_space_id, src_region_idx,
2936 closure.source());
2937 region_ptr->set_deferred_obj_addr(NULL);
2938 region_ptr->set_completed();
2939 return;
2940 }
2941
2942 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2943
2944 // Move to the next source region, possibly switching spaces as well. All
2945 // args except end_addr may be modified.
2946 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2947 end_addr);
2948 } while (true);
2949 }
2950
2951 void PSParallelCompact::fill_blocks(size_t region_idx)
2952 {
2953 // Fill in the block table elements for the specified region. Each block
2954 // table element holds the number of live words in the region that are to the
2955 // left of the first object that starts in the block. Thus only blocks in
2956 // which an object starts need to be filled.
2957 //
2958 // The algorithm scans the section of the bitmap that corresponds to the
2959 // region, keeping a running total of the live words. When an object start is
2960 // found, if it's the first to start in the block that contains it, the
2961 // current total is written to the block table element.
2962 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
2963 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
2964 const size_t RegionSize = ParallelCompactData::RegionSize;
2965
2966 ParallelCompactData& sd = summary_data();
2967 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
2968 if (partial_obj_size >= RegionSize) {
2969 return; // No objects start in this region.
2970 }
2971
2972 // Ensure the first loop iteration decides that the block has changed.
2973 size_t cur_block = sd.block_count();
2974
2975 const ParMarkBitMap* const bitmap = mark_bitmap();
2976
2977 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
2978 assert((size_t)1 << Log2BitsPerBlock ==
2979 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
2980
2981 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
2982 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
2983 size_t live_bits = bitmap->words_to_bits(partial_obj_size);
2984 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
2985 while (beg_bit < range_end) {
2986 const size_t new_block = beg_bit >> Log2BitsPerBlock;
2987 if (new_block != cur_block) {
2988 cur_block = new_block;
2989 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
2990 }
2991
2992 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
2993 if (end_bit < range_end - 1) {
2994 live_bits += end_bit - beg_bit + 1;
2995 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
2996 } else {
2997 return;
2998 }
2999 }
3000 }
3001
3002 void
3003 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
3004 const MutableSpace* sp = space(space_id);
3005 if (sp->is_empty()) {
3006 return;
3007 }
3008
3009 ParallelCompactData& sd = PSParallelCompact::summary_data();
3010 ParMarkBitMap* const bitmap = mark_bitmap();
3011 HeapWord* const dp_addr = dense_prefix(space_id);
3012 HeapWord* beg_addr = sp->bottom();
3013 HeapWord* end_addr = sp->top();
3014
3015 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
3016
3017 const size_t beg_region = sd.addr_to_region_idx(beg_addr);
3018 const size_t dp_region = sd.addr_to_region_idx(dp_addr);
3019 if (beg_region < dp_region) {
3020 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
3021 }
3022
3023 // The destination of the first live object that starts in the region is one
3024 // past the end of the partial object entering the region (if any).
3025 HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3026 HeapWord* const new_top = _space_info[space_id].new_top();
3027 assert(new_top >= dest_addr, "bad new_top value");
3028 const size_t words = pointer_delta(new_top, dest_addr);
3029
3030 if (words > 0) {
3031 ObjectStartArray* start_array = _space_info[space_id].start_array();
3032 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3033
3034 ParMarkBitMap::IterationStatus status;
3035 status = bitmap->iterate(&closure, dest_addr, end_addr);
3036 assert(status == ParMarkBitMap::full, "iteration not complete");
3037 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3038 "live objects skipped because closure is full");
3039 }
3040 }
3041
3042 jlong PSParallelCompact::millis_since_last_gc() {
3043 // We need a monotonically non-decreasing time in ms but
3044 // os::javaTimeMillis() does not guarantee monotonicity.
3045 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3046 jlong ret_val = now - _time_of_last_gc;
3047 // XXX See note in genCollectedHeap::millis_since_last_gc().
3048 if (ret_val < 0) {
3049 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);)
3050 return 0;
3051 }
3052 return ret_val;
3053 }
3054
3055 void PSParallelCompact::reset_millis_since_last_gc() {
3056 // We need a monotonically non-decreasing time in ms but
3057 // os::javaTimeMillis() does not guarantee monotonicity.
3058 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3059 }
3060
3061 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3062 {
3063 if (source() != destination()) {
3064 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3065 Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3066 }
3067 update_state(words_remaining());
3068 assert(is_full(), "sanity");
3069 return ParMarkBitMap::full;
3070 }
3071
3072 void MoveAndUpdateClosure::copy_partial_obj()
3073 {
3074 size_t words = words_remaining();
3075
3076 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3077 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3078 if (end_addr < range_end) {
3079 words = bitmap()->obj_size(source(), end_addr);
3080 }
3081
3082 // This test is necessary; if omitted, the pointer updates to a partial object
3083 // that crosses the dense prefix boundary could be overwritten.
3084 if (source() != destination()) {
3085 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3086 Copy::aligned_conjoint_words(source(), destination(), words);
3087 }
3088 update_state(words);
3089 }
3090
3091 ParMarkBitMapClosure::IterationStatus
3092 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3093 assert(destination() != NULL, "sanity");
3094 assert(bitmap()->obj_size(addr) == words, "bad size");
3095
3096 _source = addr;
3097 assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) ==
3098 destination(), "wrong destination");
3099
3100 if (words > words_remaining()) {
3101 return ParMarkBitMap::would_overflow;
3102 }
3103
3104 // The start_array must be updated even if the object is not moving.
3105 if (_start_array != NULL) {
3106 _start_array->allocate_block(destination());
3107 }
3108
3109 if (destination() != source()) {
3110 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3111 Copy::aligned_conjoint_words(source(), destination(), words);
3112 }
3113
3114 oop moved_oop = (oop) destination();
3115 compaction_manager()->update_contents(moved_oop);
3116 assert(oopDesc::is_oop_or_null(moved_oop), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop));
3117
3118 update_state(words);
3119 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3120 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3121 }
3122
3123 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3124 ParCompactionManager* cm,
3125 PSParallelCompact::SpaceId space_id) :
3126 ParMarkBitMapClosure(mbm, cm),
3127 _space_id(space_id),
3128 _start_array(PSParallelCompact::start_array(space_id))
3129 {
3130 }
3131
3132 // Updates the references in the object to their new values.
3133 ParMarkBitMapClosure::IterationStatus
3134 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3135 do_addr(addr);
3136 return ParMarkBitMap::incomplete;
3137 }
3138
3139 FillClosure::FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) :
3140 ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm),
3141 _start_array(PSParallelCompact::start_array(space_id))
3142 {
3143 assert(space_id == PSParallelCompact::old_space_id,
3144 "cannot use FillClosure in the young gen");
3145 }
3146
3147 ParMarkBitMapClosure::IterationStatus
3148 FillClosure::do_addr(HeapWord* addr, size_t size) {
3149 CollectedHeap::fill_with_objects(addr, size);
3150 HeapWord* const end = addr + size;
3151 do {
3152 _start_array->allocate_block(addr);
3153 addr += oop(addr)->size();
3154 } while (addr < end);
3155 return ParMarkBitMap::incomplete;
3156 }