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