1 /*
2 * Copyright (c) 2005, 2018, 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/javaClasses.inline.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "classfile/symbolTable.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "code/codeCache.hpp"
32 #include "gc/parallel/gcTaskManager.hpp"
33 #include "gc/parallel/parallelScavengeHeap.inline.hpp"
34 #include "gc/parallel/parMarkBitMap.inline.hpp"
35 #include "gc/parallel/pcTasks.hpp"
36 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
37 #include "gc/parallel/psCompactionManager.inline.hpp"
38 #include "gc/parallel/psOldGen.hpp"
39 #include "gc/parallel/psParallelCompact.inline.hpp"
40 #include "gc/parallel/psPromotionManager.inline.hpp"
41 #include "gc/parallel/psScavenge.hpp"
42 #include "gc/parallel/psYoungGen.hpp"
43 #include "gc/shared/gcCause.hpp"
44 #include "gc/shared/gcHeapSummary.hpp"
45 #include "gc/shared/gcId.hpp"
46 #include "gc/shared/gcLocker.hpp"
47 #include "gc/shared/gcTimer.hpp"
48 #include "gc/shared/gcTrace.hpp"
49 #include "gc/shared/gcTraceTime.inline.hpp"
50 #include "gc/shared/isGCActiveMark.hpp"
51 #include "gc/shared/referencePolicy.hpp"
52 #include "gc/shared/referenceProcessor.hpp"
53 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
54 #include "gc/shared/spaceDecorator.hpp"
55 #include "gc/shared/weakProcessor.hpp"
56 #include "logging/log.hpp"
57 #include "memory/iterator.inline.hpp"
58 #include "memory/resourceArea.hpp"
59 #include "oops/access.inline.hpp"
60 #include "oops/instanceClassLoaderKlass.inline.hpp"
61 #include "oops/instanceKlass.inline.hpp"
62 #include "oops/instanceMirrorKlass.inline.hpp"
63 #include "oops/methodData.hpp"
64 #include "oops/objArrayKlass.inline.hpp"
65 #include "oops/oop.inline.hpp"
66 #include "runtime/atomic.hpp"
67 #include "runtime/handles.inline.hpp"
68 #include "runtime/safepoint.hpp"
69 #include "runtime/vmThread.hpp"
70 #include "services/management.hpp"
71 #include "services/memTracker.hpp"
72 #include "services/memoryService.hpp"
73 #include "utilities/align.hpp"
74 #include "utilities/debug.hpp"
75 #include "utilities/events.hpp"
76 #include "utilities/formatBuffer.hpp"
77 #include "utilities/macros.hpp"
78 #include "utilities/stack.inline.hpp"
79
80 #include <math.h>
81
82 // All sizes are in HeapWords.
83 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words
84 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
85 const size_t ParallelCompactData::RegionSizeBytes =
86 RegionSize << LogHeapWordSize;
87 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
88 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
89 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
90
91 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words
92 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize;
93 const size_t ParallelCompactData::BlockSizeBytes =
94 BlockSize << LogHeapWordSize;
95 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1;
96 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1;
97 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask;
98
99 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
100 const size_t ParallelCompactData::Log2BlocksPerRegion =
101 Log2RegionSize - Log2BlockSize;
102
103 const ParallelCompactData::RegionData::region_sz_t
104 ParallelCompactData::RegionData::dc_shift = 27;
105
106 const ParallelCompactData::RegionData::region_sz_t
107 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
108
109 const ParallelCompactData::RegionData::region_sz_t
110 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
111
112 const ParallelCompactData::RegionData::region_sz_t
113 ParallelCompactData::RegionData::los_mask = ~dc_mask;
114
115 const ParallelCompactData::RegionData::region_sz_t
116 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
117
118 const ParallelCompactData::RegionData::region_sz_t
119 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
120
121 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
122
123 SpanSubjectToDiscoveryClosure PSParallelCompact::_span_based_discoverer;
124 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
125
126 double PSParallelCompact::_dwl_mean;
127 double PSParallelCompact::_dwl_std_dev;
128 double PSParallelCompact::_dwl_first_term;
129 double PSParallelCompact::_dwl_adjustment;
130 #ifdef ASSERT
131 bool PSParallelCompact::_dwl_initialized = false;
132 #endif // #ifdef ASSERT
133
134 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
135 HeapWord* destination)
136 {
137 assert(src_region_idx != 0, "invalid src_region_idx");
138 assert(partial_obj_size != 0, "invalid partial_obj_size argument");
139 assert(destination != NULL, "invalid destination argument");
140
141 _src_region_idx = src_region_idx;
142 _partial_obj_size = partial_obj_size;
143 _destination = destination;
144
145 // These fields may not be updated below, so make sure they're clear.
146 assert(_dest_region_addr == NULL, "should have been cleared");
147 assert(_first_src_addr == NULL, "should have been cleared");
148
149 // Determine the number of destination regions for the partial object.
150 HeapWord* const last_word = destination + partial_obj_size - 1;
151 const ParallelCompactData& sd = PSParallelCompact::summary_data();
152 HeapWord* const beg_region_addr = sd.region_align_down(destination);
153 HeapWord* const end_region_addr = sd.region_align_down(last_word);
154
155 if (beg_region_addr == end_region_addr) {
156 // One destination region.
157 _destination_count = 1;
158 if (end_region_addr == destination) {
159 // The destination falls on a region boundary, thus the first word of the
160 // partial object will be the first word copied to the destination region.
161 _dest_region_addr = end_region_addr;
162 _first_src_addr = sd.region_to_addr(src_region_idx);
163 }
164 } else {
165 // Two destination regions. When copied, the partial object will cross a
166 // destination region boundary, so a word somewhere within the partial
167 // object will be the first word copied to the second destination region.
168 _destination_count = 2;
169 _dest_region_addr = end_region_addr;
170 const size_t ofs = pointer_delta(end_region_addr, destination);
171 assert(ofs < _partial_obj_size, "sanity");
172 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
173 }
174 }
175
176 void SplitInfo::clear()
177 {
178 _src_region_idx = 0;
179 _partial_obj_size = 0;
180 _destination = NULL;
181 _destination_count = 0;
182 _dest_region_addr = NULL;
183 _first_src_addr = NULL;
184 assert(!is_valid(), "sanity");
185 }
186
187 #ifdef ASSERT
188 void SplitInfo::verify_clear()
189 {
190 assert(_src_region_idx == 0, "not clear");
191 assert(_partial_obj_size == 0, "not clear");
192 assert(_destination == NULL, "not clear");
193 assert(_destination_count == 0, "not clear");
194 assert(_dest_region_addr == NULL, "not clear");
195 assert(_first_src_addr == NULL, "not clear");
196 }
197 #endif // #ifdef ASSERT
198
199
200 void PSParallelCompact::print_on_error(outputStream* st) {
201 _mark_bitmap.print_on_error(st);
202 }
203
204 #ifndef PRODUCT
205 const char* PSParallelCompact::space_names[] = {
206 "old ", "eden", "from", "to "
207 };
208
209 void PSParallelCompact::print_region_ranges() {
210 if (!log_develop_is_enabled(Trace, gc, compaction)) {
211 return;
212 }
213 Log(gc, compaction) log;
214 ResourceMark rm;
215 LogStream ls(log.trace());
216 Universe::print_on(&ls);
217 log.trace("space bottom top end new_top");
218 log.trace("------ ---------- ---------- ---------- ----------");
219
220 for (unsigned int id = 0; id < last_space_id; ++id) {
221 const MutableSpace* space = _space_info[id].space();
222 log.trace("%u %s "
223 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
224 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
225 id, space_names[id],
226 summary_data().addr_to_region_idx(space->bottom()),
227 summary_data().addr_to_region_idx(space->top()),
228 summary_data().addr_to_region_idx(space->end()),
229 summary_data().addr_to_region_idx(_space_info[id].new_top()));
230 }
231 }
232
233 void
234 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
235 {
236 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7)
237 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5)
238
239 ParallelCompactData& sd = PSParallelCompact::summary_data();
240 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
241 log_develop_trace(gc, compaction)(
242 REGION_IDX_FORMAT " " PTR_FORMAT " "
243 REGION_IDX_FORMAT " " PTR_FORMAT " "
244 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
245 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
246 i, p2i(c->data_location()), dci, p2i(c->destination()),
247 c->partial_obj_size(), c->live_obj_size(),
248 c->data_size(), c->source_region(), c->destination_count());
249
250 #undef REGION_IDX_FORMAT
251 #undef REGION_DATA_FORMAT
252 }
253
254 void
255 print_generic_summary_data(ParallelCompactData& summary_data,
256 HeapWord* const beg_addr,
257 HeapWord* const end_addr)
258 {
259 size_t total_words = 0;
260 size_t i = summary_data.addr_to_region_idx(beg_addr);
261 const size_t last = summary_data.addr_to_region_idx(end_addr);
262 HeapWord* pdest = 0;
263
264 while (i < last) {
265 ParallelCompactData::RegionData* c = summary_data.region(i);
266 if (c->data_size() != 0 || c->destination() != pdest) {
267 print_generic_summary_region(i, c);
268 total_words += c->data_size();
269 pdest = c->destination();
270 }
271 ++i;
272 }
273
274 log_develop_trace(gc, compaction)("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
275 }
276
277 void
278 PSParallelCompact::print_generic_summary_data(ParallelCompactData& summary_data,
279 HeapWord* const beg_addr,
280 HeapWord* const end_addr) {
281 ::print_generic_summary_data(summary_data,beg_addr, end_addr);
282 }
283
284 void
285 print_generic_summary_data(ParallelCompactData& summary_data,
286 SpaceInfo* space_info)
287 {
288 if (!log_develop_is_enabled(Trace, gc, compaction)) {
289 return;
290 }
291
292 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
293 const MutableSpace* space = space_info[id].space();
294 print_generic_summary_data(summary_data, space->bottom(),
295 MAX2(space->top(), space_info[id].new_top()));
296 }
297 }
298
299 void
300 print_initial_summary_data(ParallelCompactData& summary_data,
301 const MutableSpace* space) {
302 if (space->top() == space->bottom()) {
303 return;
304 }
305
306 const size_t region_size = ParallelCompactData::RegionSize;
307 typedef ParallelCompactData::RegionData RegionData;
308 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
309 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
310 const RegionData* c = summary_data.region(end_region - 1);
311 HeapWord* end_addr = c->destination() + c->data_size();
312 const size_t live_in_space = pointer_delta(end_addr, space->bottom());
313
314 // Print (and count) the full regions at the beginning of the space.
315 size_t full_region_count = 0;
316 size_t i = summary_data.addr_to_region_idx(space->bottom());
317 while (i < end_region && summary_data.region(i)->data_size() == region_size) {
318 ParallelCompactData::RegionData* c = summary_data.region(i);
319 log_develop_trace(gc, compaction)(
320 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
321 i, p2i(c->destination()),
322 c->partial_obj_size(), c->live_obj_size(),
323 c->data_size(), c->source_region(), c->destination_count());
324 ++full_region_count;
325 ++i;
326 }
327
328 size_t live_to_right = live_in_space - full_region_count * region_size;
329
330 double max_reclaimed_ratio = 0.0;
331 size_t max_reclaimed_ratio_region = 0;
332 size_t max_dead_to_right = 0;
333 size_t max_live_to_right = 0;
334
335 // Print the 'reclaimed ratio' for regions while there is something live in
336 // the region or to the right of it. The remaining regions are empty (and
337 // uninteresting), and computing the ratio will result in division by 0.
338 while (i < end_region && live_to_right > 0) {
339 c = summary_data.region(i);
340 HeapWord* const region_addr = summary_data.region_to_addr(i);
341 const size_t used_to_right = pointer_delta(space->top(), region_addr);
342 const size_t dead_to_right = used_to_right - live_to_right;
343 const double reclaimed_ratio = double(dead_to_right) / live_to_right;
344
345 if (reclaimed_ratio > max_reclaimed_ratio) {
346 max_reclaimed_ratio = reclaimed_ratio;
347 max_reclaimed_ratio_region = i;
348 max_dead_to_right = dead_to_right;
349 max_live_to_right = live_to_right;
350 }
351
352 ParallelCompactData::RegionData* c = summary_data.region(i);
353 log_develop_trace(gc, compaction)(
354 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d"
355 "%12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
356 i, p2i(c->destination()),
357 c->partial_obj_size(), c->live_obj_size(),
358 c->data_size(), c->source_region(), c->destination_count(),
359 reclaimed_ratio, dead_to_right, live_to_right);
360
361
362 live_to_right -= c->data_size();
363 ++i;
364 }
365
366 // Any remaining regions are empty. Print one more if there is one.
367 if (i < end_region) {
368 ParallelCompactData::RegionData* c = summary_data.region(i);
369 log_develop_trace(gc, compaction)(
370 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
371 i, p2i(c->destination()),
372 c->partial_obj_size(), c->live_obj_size(),
373 c->data_size(), c->source_region(), c->destination_count());
374 }
375
376 log_develop_trace(gc, compaction)("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
377 max_reclaimed_ratio_region, max_dead_to_right, max_live_to_right, max_reclaimed_ratio);
378 }
379
380 void
381 print_initial_summary_data(ParallelCompactData& summary_data,
382 SpaceInfo* space_info) {
383 if (!log_develop_is_enabled(Trace, gc, compaction)) {
384 return;
385 }
386
387 unsigned int id = PSParallelCompact::old_space_id;
388 const MutableSpace* space;
389 do {
390 space = space_info[id].space();
391 print_initial_summary_data(summary_data, space);
392 } while (++id < PSParallelCompact::eden_space_id);
393
394 do {
395 space = space_info[id].space();
396 print_generic_summary_data(summary_data, space->bottom(), space->top());
397 } while (++id < PSParallelCompact::last_space_id);
398 }
399 #endif // #ifndef PRODUCT
400
401 #ifdef ASSERT
402 size_t add_obj_count;
403 size_t add_obj_size;
404 size_t mark_bitmap_count;
405 size_t mark_bitmap_size;
406 #endif // #ifdef ASSERT
407
408 ParallelCompactData::ParallelCompactData()
409 {
410 _region_start = 0;
411
412 _region_vspace = 0;
413 _reserved_byte_size = 0;
414 _region_data = 0;
415 _region_count = 0;
416
417 _block_vspace = 0;
418 _block_data = 0;
419 _block_count = 0;
420 }
421
422 bool ParallelCompactData::initialize(MemRegion covered_region)
423 {
424 _region_start = covered_region.start();
425 const size_t region_size = covered_region.word_size();
426 DEBUG_ONLY(_region_end = _region_start + region_size;)
427
428 assert(region_align_down(_region_start) == _region_start,
429 "region start not aligned");
430 assert((region_size & RegionSizeOffsetMask) == 0,
431 "region size not a multiple of RegionSize");
432
433 bool result = initialize_region_data(region_size) && initialize_block_data();
434 return result;
435 }
436
437 PSVirtualSpace*
438 ParallelCompactData::create_vspace(size_t count, size_t element_size)
439 {
440 const size_t raw_bytes = count * element_size;
441 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
442 const size_t granularity = os::vm_allocation_granularity();
443 _reserved_byte_size = align_up(raw_bytes, MAX2(page_sz, granularity));
444
445 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
446 MAX2(page_sz, granularity);
447 ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0);
448 os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, page_sz, rs.base(),
449 rs.size());
450
451 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
452
453 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
454 if (vspace != 0) {
455 if (vspace->expand_by(_reserved_byte_size)) {
456 return vspace;
457 }
458 delete vspace;
459 // Release memory reserved in the space.
460 rs.release();
461 }
462
463 return 0;
464 }
465
466 bool ParallelCompactData::initialize_region_data(size_t region_size)
467 {
468 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
469 _region_vspace = create_vspace(count, sizeof(RegionData));
470 if (_region_vspace != 0) {
471 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
472 _region_count = count;
473 return true;
474 }
475 return false;
476 }
477
478 bool ParallelCompactData::initialize_block_data()
479 {
480 assert(_region_count != 0, "region data must be initialized first");
481 const size_t count = _region_count << Log2BlocksPerRegion;
482 _block_vspace = create_vspace(count, sizeof(BlockData));
483 if (_block_vspace != 0) {
484 _block_data = (BlockData*)_block_vspace->reserved_low_addr();
485 _block_count = count;
486 return true;
487 }
488 return false;
489 }
490
491 void ParallelCompactData::clear()
492 {
493 memset(_region_data, 0, _region_vspace->committed_size());
494 memset(_block_data, 0, _block_vspace->committed_size());
495 }
496
497 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
498 assert(beg_region <= _region_count, "beg_region out of range");
499 assert(end_region <= _region_count, "end_region out of range");
500 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize");
501
502 const size_t region_cnt = end_region - beg_region;
503 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
504
505 const size_t beg_block = beg_region * BlocksPerRegion;
506 const size_t block_cnt = region_cnt * BlocksPerRegion;
507 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));
508 }
509
510 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
511 {
512 const RegionData* cur_cp = region(region_idx);
513 const RegionData* const end_cp = region(region_count() - 1);
514
515 HeapWord* result = region_to_addr(region_idx);
516 if (cur_cp < end_cp) {
517 do {
518 result += cur_cp->partial_obj_size();
519 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
520 }
521 return result;
522 }
523
524 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
525 {
526 const size_t obj_ofs = pointer_delta(addr, _region_start);
527 const size_t beg_region = obj_ofs >> Log2RegionSize;
528 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
529
530 DEBUG_ONLY(Atomic::inc(&add_obj_count);)
531 DEBUG_ONLY(Atomic::add(len, &add_obj_size);)
532
533 if (beg_region == end_region) {
534 // All in one region.
535 _region_data[beg_region].add_live_obj(len);
536 return;
537 }
538
539 // First region.
540 const size_t beg_ofs = region_offset(addr);
541 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
542
543 Klass* klass = ((oop)addr)->klass();
544 // Middle regions--completely spanned by this object.
545 for (size_t region = beg_region + 1; region < end_region; ++region) {
546 _region_data[region].set_partial_obj_size(RegionSize);
547 _region_data[region].set_partial_obj_addr(addr);
548 }
549
550 // Last region.
551 const size_t end_ofs = region_offset(addr + len - 1);
552 _region_data[end_region].set_partial_obj_size(end_ofs + 1);
553 _region_data[end_region].set_partial_obj_addr(addr);
554 }
555
556 void
557 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
558 {
559 assert(region_offset(beg) == 0, "not RegionSize aligned");
560 assert(region_offset(end) == 0, "not RegionSize aligned");
561
562 size_t cur_region = addr_to_region_idx(beg);
563 const size_t end_region = addr_to_region_idx(end);
564 HeapWord* addr = beg;
565 while (cur_region < end_region) {
566 _region_data[cur_region].set_destination(addr);
567 _region_data[cur_region].set_destination_count(0);
568 _region_data[cur_region].set_source_region(cur_region);
569 _region_data[cur_region].set_data_location(addr);
570
571 // Update live_obj_size so the region appears completely full.
572 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
573 _region_data[cur_region].set_live_obj_size(live_size);
574
575 ++cur_region;
576 addr += RegionSize;
577 }
578 }
579
580 // Find the point at which a space can be split and, if necessary, record the
581 // split point.
582 //
583 // If the current src region (which overflowed the destination space) doesn't
584 // have a partial object, the split point is at the beginning of the current src
585 // region (an "easy" split, no extra bookkeeping required).
586 //
587 // If the current src region has a partial object, the split point is in the
588 // region where that partial object starts (call it the split_region). If
589 // split_region has a partial object, then the split point is just after that
590 // partial object (a "hard" split where we have to record the split data and
591 // zero the partial_obj_size field). With a "hard" split, we know that the
592 // partial_obj ends within split_region because the partial object that caused
593 // the overflow starts in split_region. If split_region doesn't have a partial
594 // obj, then the split is at the beginning of split_region (another "easy"
595 // split).
596 HeapWord*
597 ParallelCompactData::summarize_split_space(size_t src_region,
598 SplitInfo& split_info,
599 HeapWord* destination,
600 HeapWord* target_end,
601 HeapWord** target_next)
602 {
603 assert(destination <= target_end, "sanity");
604 assert(destination + _region_data[src_region].data_size() > target_end,
605 "region should not fit into target space");
606 assert(is_region_aligned(target_end), "sanity");
607
608 size_t split_region = src_region;
609 HeapWord* split_destination = destination;
610 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
611
612 if (destination + partial_obj_size > target_end) {
613 // The split point is just after the partial object (if any) in the
614 // src_region that contains the start of the object that overflowed the
615 // destination space.
616 //
617 // Find the start of the "overflow" object and set split_region to the
618 // region containing it.
619 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
620 split_region = addr_to_region_idx(overflow_obj);
621
622 // Clear the source_region field of all destination regions whose first word
623 // came from data after the split point (a non-null source_region field
624 // implies a region must be filled).
625 //
626 // An alternative to the simple loop below: clear during post_compact(),
627 // which uses memcpy instead of individual stores, and is easy to
628 // parallelize. (The downside is that it clears the entire RegionData
629 // object as opposed to just one field.)
630 //
631 // post_compact() would have to clear the summary data up to the highest
632 // address that was written during the summary phase, which would be
633 //
634 // max(top, max(new_top, clear_top))
635 //
636 // where clear_top is a new field in SpaceInfo. Would have to set clear_top
637 // to target_end.
638 const RegionData* const sr = region(split_region);
639 const size_t beg_idx =
640 addr_to_region_idx(region_align_up(sr->destination() +
641 sr->partial_obj_size()));
642 const size_t end_idx = addr_to_region_idx(target_end);
643
644 log_develop_trace(gc, compaction)("split: clearing source_region field in [" SIZE_FORMAT ", " SIZE_FORMAT ")", beg_idx, end_idx);
645 for (size_t idx = beg_idx; idx < end_idx; ++idx) {
646 _region_data[idx].set_source_region(0);
647 }
648
649 // Set split_destination and partial_obj_size to reflect the split region.
650 split_destination = sr->destination();
651 partial_obj_size = sr->partial_obj_size();
652 }
653
654 // The split is recorded only if a partial object extends onto the region.
655 if (partial_obj_size != 0) {
656 _region_data[split_region].set_partial_obj_size(0);
657 split_info.record(split_region, partial_obj_size, split_destination);
658 }
659
660 // Setup the continuation addresses.
661 *target_next = split_destination + partial_obj_size;
662 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
663
664 if (log_develop_is_enabled(Trace, gc, compaction)) {
665 const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
666 log_develop_trace(gc, compaction)("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT " pos=" SIZE_FORMAT,
667 split_type, p2i(source_next), split_region, partial_obj_size);
668 log_develop_trace(gc, compaction)("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT " tn=" PTR_FORMAT,
669 split_type, p2i(split_destination),
670 addr_to_region_idx(split_destination),
671 p2i(*target_next));
672
673 if (partial_obj_size != 0) {
674 HeapWord* const po_beg = split_info.destination();
675 HeapWord* const po_end = po_beg + split_info.partial_obj_size();
676 log_develop_trace(gc, compaction)("%s split: po_beg=" PTR_FORMAT " " SIZE_FORMAT " po_end=" PTR_FORMAT " " SIZE_FORMAT,
677 split_type,
678 p2i(po_beg), addr_to_region_idx(po_beg),
679 p2i(po_end), addr_to_region_idx(po_end));
680 }
681 }
682
683 return source_next;
684 }
685
686 bool ParallelCompactData::summarize(SplitInfo& split_info,
687 HeapWord* source_beg, HeapWord* source_end,
688 HeapWord** source_next,
689 HeapWord* target_beg, HeapWord* target_end,
690 HeapWord** target_next)
691 {
692 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
693 log_develop_trace(gc, compaction)(
694 "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
695 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
696 p2i(source_beg), p2i(source_end), p2i(source_next_val),
697 p2i(target_beg), p2i(target_end), p2i(*target_next));
698
699 size_t cur_region = addr_to_region_idx(source_beg);
700 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
701
702 HeapWord *dest_addr = target_beg;
703 while (cur_region < end_region) {
704 // The destination must be set even if the region has no data.
705 _region_data[cur_region].set_destination(dest_addr);
706
707 size_t words = _region_data[cur_region].data_size();
708 if (words > 0) {
709 // If cur_region does not fit entirely into the target space, find a point
710 // at which the source space can be 'split' so that part is copied to the
711 // target space and the rest is copied elsewhere.
712 if (dest_addr + words > target_end) {
713 assert(source_next != NULL, "source_next is NULL when splitting");
714 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
715 target_end, target_next);
716 return false;
717 }
718
719 // Compute the destination_count for cur_region, and if necessary, update
720 // source_region for a destination region. The source_region field is
721 // updated if cur_region is the first (left-most) region to be copied to a
722 // destination region.
723 //
724 // The destination_count calculation is a bit subtle. A region that has
725 // data that compacts into itself does not count itself as a destination.
726 // This maintains the invariant that a zero count means the region is
727 // available and can be claimed and then filled.
728 uint destination_count = 0;
729 if (split_info.is_split(cur_region)) {
730 // The current region has been split: the partial object will be copied
731 // to one destination space and the remaining data will be copied to
732 // another destination space. Adjust the initial destination_count and,
733 // if necessary, set the source_region field if the partial object will
734 // cross a destination region boundary.
735 destination_count = split_info.destination_count();
736 if (destination_count == 2) {
737 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
738 _region_data[dest_idx].set_source_region(cur_region);
739 }
740 }
741
742 HeapWord* const last_addr = dest_addr + words - 1;
743 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
744 const size_t dest_region_2 = addr_to_region_idx(last_addr);
745
746 // Initially assume that the destination regions will be the same and
747 // adjust the value below if necessary. Under this assumption, if
748 // cur_region == dest_region_2, then cur_region will be compacted
749 // completely into itself.
750 destination_count += cur_region == dest_region_2 ? 0 : 1;
751 if (dest_region_1 != dest_region_2) {
752 // Destination regions differ; adjust destination_count.
753 destination_count += 1;
754 // Data from cur_region will be copied to the start of dest_region_2.
755 _region_data[dest_region_2].set_source_region(cur_region);
756 } else if (region_offset(dest_addr) == 0) {
757 // Data from cur_region will be copied to the start of the destination
758 // region.
759 _region_data[dest_region_1].set_source_region(cur_region);
760 }
761
762 _region_data[cur_region].set_destination_count(destination_count);
763 _region_data[cur_region].set_data_location(region_to_addr(cur_region));
764 dest_addr += words;
765 }
766
767 ++cur_region;
768 }
769
770 *target_next = dest_addr;
771 return true;
772 }
773
774 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr, ParCompactionManager* cm) {
775 assert(addr != NULL, "Should detect NULL oop earlier");
776 assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap");
777 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked");
778
779 // Region covering the object.
780 RegionData* const region_ptr = addr_to_region_ptr(addr);
781 HeapWord* result = region_ptr->destination();
782
783 // If the entire Region is live, the new location is region->destination + the
784 // offset of the object within in the Region.
785
786 // Run some performance tests to determine if this special case pays off. It
787 // is worth it for pointers into the dense prefix. If the optimization to
788 // avoid pointer updates in regions that only point to the dense prefix is
789 // ever implemented, this should be revisited.
790 if (region_ptr->data_size() == RegionSize) {
791 result += region_offset(addr);
792 return result;
793 }
794
795 // Otherwise, the new location is region->destination + block offset + the
796 // number of live words in the Block that are (a) to the left of addr and (b)
797 // due to objects that start in the Block.
798
799 // Fill in the block table if necessary. This is unsynchronized, so multiple
800 // threads may fill the block table for a region (harmless, since it is
801 // idempotent).
802 if (!region_ptr->blocks_filled()) {
803 PSParallelCompact::fill_blocks(addr_to_region_idx(addr));
804 region_ptr->set_blocks_filled();
805 }
806
807 HeapWord* const search_start = block_align_down(addr);
808 const size_t block_offset = addr_to_block_ptr(addr)->offset();
809
810 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
811 const size_t live = bitmap->live_words_in_range(cm, search_start, oop(addr));
812 result += block_offset + live;
813 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result));
814 return result;
815 }
816
817 #ifdef ASSERT
818 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
819 {
820 const size_t* const beg = (const size_t*)vspace->committed_low_addr();
821 const size_t* const end = (const size_t*)vspace->committed_high_addr();
822 for (const size_t* p = beg; p < end; ++p) {
823 assert(*p == 0, "not zero");
824 }
825 }
826
827 void ParallelCompactData::verify_clear()
828 {
829 verify_clear(_region_vspace);
830 verify_clear(_block_vspace);
831 }
832 #endif // #ifdef ASSERT
833
834 STWGCTimer PSParallelCompact::_gc_timer;
835 ParallelOldTracer PSParallelCompact::_gc_tracer;
836 elapsedTimer PSParallelCompact::_accumulated_time;
837 unsigned int PSParallelCompact::_total_invocations = 0;
838 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
839 jlong PSParallelCompact::_time_of_last_gc = 0;
840 CollectorCounters* PSParallelCompact::_counters = NULL;
841 ParMarkBitMap PSParallelCompact::_mark_bitmap;
842 ParallelCompactData PSParallelCompact::_summary_data;
843
844 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
845
846 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
847
848 void PSParallelCompact::post_initialize() {
849 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
850 _span_based_discoverer.set_span(heap->reserved_region());
851 _ref_processor =
852 new ReferenceProcessor(&_span_based_discoverer,
853 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
854 ParallelGCThreads, // mt processing degree
855 true, // mt discovery
856 ParallelGCThreads, // mt discovery degree
857 true, // atomic_discovery
858 &_is_alive_closure, // non-header is alive closure
859 false); // disable adjusting number of processing threads
860 _counters = new CollectorCounters("PSParallelCompact", 1);
861
862 // Initialize static fields in ParCompactionManager.
863 ParCompactionManager::initialize(mark_bitmap());
864 }
865
866 bool PSParallelCompact::initialize() {
867 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
868 MemRegion mr = heap->reserved_region();
869
870 // Was the old gen get allocated successfully?
871 if (!heap->old_gen()->is_allocated()) {
872 return false;
873 }
874
875 initialize_space_info();
876 initialize_dead_wood_limiter();
877
878 if (!_mark_bitmap.initialize(mr)) {
879 vm_shutdown_during_initialization(
880 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
881 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
882 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
883 return false;
884 }
885
886 if (!_summary_data.initialize(mr)) {
887 vm_shutdown_during_initialization(
888 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
889 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
890 _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
891 return false;
892 }
893
894 return true;
895 }
896
897 void PSParallelCompact::initialize_space_info()
898 {
899 memset(&_space_info, 0, sizeof(_space_info));
900
901 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
902 PSYoungGen* young_gen = heap->young_gen();
903
904 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
905 _space_info[eden_space_id].set_space(young_gen->eden_space());
906 _space_info[from_space_id].set_space(young_gen->from_space());
907 _space_info[to_space_id].set_space(young_gen->to_space());
908
909 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
910 }
911
912 void PSParallelCompact::initialize_dead_wood_limiter()
913 {
914 const size_t max = 100;
915 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
916 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
917 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
918 DEBUG_ONLY(_dwl_initialized = true;)
919 _dwl_adjustment = normal_distribution(1.0);
920 }
921
922 void
923 PSParallelCompact::clear_data_covering_space(SpaceId id)
924 {
925 // At this point, top is the value before GC, new_top() is the value that will
926 // be set at the end of GC. The marking bitmap is cleared to top; nothing
927 // should be marked above top. The summary data is cleared to the larger of
928 // top & new_top.
929 MutableSpace* const space = _space_info[id].space();
930 HeapWord* const bot = space->bottom();
931 HeapWord* const top = space->top();
932 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
933
934 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
935 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
936 _mark_bitmap.clear_range(beg_bit, end_bit);
937
938 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
939 const size_t end_region =
940 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
941 _summary_data.clear_range(beg_region, end_region);
942
943 // Clear the data used to 'split' regions.
944 SplitInfo& split_info = _space_info[id].split_info();
945 if (split_info.is_valid()) {
946 split_info.clear();
947 }
948 DEBUG_ONLY(split_info.verify_clear();)
949 }
950
951 void PSParallelCompact::pre_compact()
952 {
953 // Update the from & to space pointers in space_info, since they are swapped
954 // at each young gen gc. Do the update unconditionally (even though a
955 // promotion failure does not swap spaces) because an unknown number of young
956 // collections will have swapped the spaces an unknown number of times.
957 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer);
958 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
959 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
960 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
961
962 DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
963 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
964
965 // Increment the invocation count
966 heap->increment_total_collections(true);
967
968 // We need to track unique mark sweep invocations as well.
969 _total_invocations++;
970
971 heap->print_heap_before_gc();
972 heap->trace_heap_before_gc(&_gc_tracer);
973
974 // Fill in TLABs
975 heap->ensure_parsability(true); // retire TLABs
976
977 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
978 HandleMark hm; // Discard invalid handles created during verification
979 Universe::verify("Before GC");
980 }
981
982 // Verify object start arrays
983 if (VerifyObjectStartArray &&
984 VerifyBeforeGC) {
985 heap->old_gen()->verify_object_start_array();
986 }
987
988 DEBUG_ONLY(mark_bitmap()->verify_clear();)
989 DEBUG_ONLY(summary_data().verify_clear();)
990
991 // Have worker threads release resources the next time they run a task.
992 gc_task_manager()->release_all_resources();
993
994 ParCompactionManager::reset_all_bitmap_query_caches();
995 }
996
997 void PSParallelCompact::post_compact()
998 {
999 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer);
1000
1001 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1002 // Clear the marking bitmap, summary data and split info.
1003 clear_data_covering_space(SpaceId(id));
1004 // Update top(). Must be done after clearing the bitmap and summary data.
1005 _space_info[id].publish_new_top();
1006 }
1007
1008 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1009 MutableSpace* const from_space = _space_info[from_space_id].space();
1010 MutableSpace* const to_space = _space_info[to_space_id].space();
1011
1012 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1013 bool eden_empty = eden_space->is_empty();
1014 if (!eden_empty) {
1015 eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1016 heap->young_gen(), heap->old_gen());
1017 }
1018
1019 // Update heap occupancy information which is used as input to the soft ref
1020 // clearing policy at the next gc.
1021 Universe::update_heap_info_at_gc();
1022
1023 bool young_gen_empty = eden_empty && from_space->is_empty() &&
1024 to_space->is_empty();
1025
1026 PSCardTable* ct = heap->card_table();
1027 MemRegion old_mr = heap->old_gen()->reserved();
1028 if (young_gen_empty) {
1029 ct->clear(MemRegion(old_mr.start(), old_mr.end()));
1030 } else {
1031 ct->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1032 }
1033
1034 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1035 ClassLoaderDataGraph::purge();
1036 MetaspaceUtils::verify_metrics();
1037
1038 CodeCache::gc_epilogue();
1039 JvmtiExport::gc_epilogue();
1040
1041 #if COMPILER2_OR_JVMCI
1042 DerivedPointerTable::update_pointers();
1043 #endif
1044
1045 if (ZapUnusedHeapArea) {
1046 heap->gen_mangle_unused_area();
1047 }
1048
1049 // Update time of last GC
1050 reset_millis_since_last_gc();
1051 }
1052
1053 HeapWord*
1054 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1055 bool maximum_compaction)
1056 {
1057 const size_t region_size = ParallelCompactData::RegionSize;
1058 const ParallelCompactData& sd = summary_data();
1059
1060 const MutableSpace* const space = _space_info[id].space();
1061 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1062 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1063 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1064
1065 // Skip full regions at the beginning of the space--they are necessarily part
1066 // of the dense prefix.
1067 size_t full_count = 0;
1068 const RegionData* cp;
1069 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1070 ++full_count;
1071 }
1072
1073 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1074 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1075 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1076 if (maximum_compaction || cp == end_cp || interval_ended) {
1077 _maximum_compaction_gc_num = total_invocations();
1078 return sd.region_to_addr(cp);
1079 }
1080
1081 HeapWord* const new_top = _space_info[id].new_top();
1082 const size_t space_live = pointer_delta(new_top, space->bottom());
1083 const size_t space_used = space->used_in_words();
1084 const size_t space_capacity = space->capacity_in_words();
1085
1086 const double cur_density = double(space_live) / space_capacity;
1087 const double deadwood_density =
1088 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1089 const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1090
1091 if (TraceParallelOldGCDensePrefix) {
1092 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1093 cur_density, deadwood_density, deadwood_goal);
1094 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1095 "space_cap=" SIZE_FORMAT,
1096 space_live, space_used,
1097 space_capacity);
1098 }
1099
1100 // XXX - Use binary search?
1101 HeapWord* dense_prefix = sd.region_to_addr(cp);
1102 const RegionData* full_cp = cp;
1103 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1104 while (cp < end_cp) {
1105 HeapWord* region_destination = cp->destination();
1106 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1107 if (TraceParallelOldGCDensePrefix && Verbose) {
1108 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1109 "dp=" PTR_FORMAT " " "cdw=" SIZE_FORMAT_W(8),
1110 sd.region(cp), p2i(region_destination),
1111 p2i(dense_prefix), cur_deadwood);
1112 }
1113
1114 if (cur_deadwood >= deadwood_goal) {
1115 // Found the region that has the correct amount of deadwood to the left.
1116 // This typically occurs after crossing a fairly sparse set of regions, so
1117 // iterate backwards over those sparse regions, looking for the region
1118 // that has the lowest density of live objects 'to the right.'
1119 size_t space_to_left = sd.region(cp) * region_size;
1120 size_t live_to_left = space_to_left - cur_deadwood;
1121 size_t space_to_right = space_capacity - space_to_left;
1122 size_t live_to_right = space_live - live_to_left;
1123 double density_to_right = double(live_to_right) / space_to_right;
1124 while (cp > full_cp) {
1125 --cp;
1126 const size_t prev_region_live_to_right = live_to_right -
1127 cp->data_size();
1128 const size_t prev_region_space_to_right = space_to_right + region_size;
1129 double prev_region_density_to_right =
1130 double(prev_region_live_to_right) / prev_region_space_to_right;
1131 if (density_to_right <= prev_region_density_to_right) {
1132 return dense_prefix;
1133 }
1134 if (TraceParallelOldGCDensePrefix && Verbose) {
1135 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1136 "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1137 prev_region_density_to_right);
1138 }
1139 dense_prefix -= region_size;
1140 live_to_right = prev_region_live_to_right;
1141 space_to_right = prev_region_space_to_right;
1142 density_to_right = prev_region_density_to_right;
1143 }
1144 return dense_prefix;
1145 }
1146
1147 dense_prefix += region_size;
1148 ++cp;
1149 }
1150
1151 return dense_prefix;
1152 }
1153
1154 #ifndef PRODUCT
1155 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1156 const SpaceId id,
1157 const bool maximum_compaction,
1158 HeapWord* const addr)
1159 {
1160 const size_t region_idx = summary_data().addr_to_region_idx(addr);
1161 RegionData* const cp = summary_data().region(region_idx);
1162 const MutableSpace* const space = _space_info[id].space();
1163 HeapWord* const new_top = _space_info[id].new_top();
1164
1165 const size_t space_live = pointer_delta(new_top, space->bottom());
1166 const size_t dead_to_left = pointer_delta(addr, cp->destination());
1167 const size_t space_cap = space->capacity_in_words();
1168 const double dead_to_left_pct = double(dead_to_left) / space_cap;
1169 const size_t live_to_right = new_top - cp->destination();
1170 const size_t dead_to_right = space->top() - addr - live_to_right;
1171
1172 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1173 "spl=" SIZE_FORMAT " "
1174 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1175 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1176 " ratio=%10.8f",
1177 algorithm, p2i(addr), region_idx,
1178 space_live,
1179 dead_to_left, dead_to_left_pct,
1180 dead_to_right, live_to_right,
1181 double(dead_to_right) / live_to_right);
1182 }
1183 #endif // #ifndef PRODUCT
1184
1185 // Return a fraction indicating how much of the generation can be treated as
1186 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution
1187 // based on the density of live objects in the generation to determine a limit,
1188 // which is then adjusted so the return value is min_percent when the density is
1189 // 1.
1190 //
1191 // The following table shows some return values for a different values of the
1192 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1193 // min_percent is 1.
1194 //
1195 // fraction allowed as dead wood
1196 // -----------------------------------------------------------------
1197 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1198 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1199 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1200 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1201 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1202 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1203 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1204 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1205 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1206 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1207 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1208 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1209 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1210 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1211 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1212 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1213 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1214 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1215 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1216 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1217 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1218 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1219 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1220
1221 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1222 {
1223 assert(_dwl_initialized, "uninitialized");
1224
1225 // The raw limit is the value of the normal distribution at x = density.
1226 const double raw_limit = normal_distribution(density);
1227
1228 // Adjust the raw limit so it becomes the minimum when the density is 1.
1229 //
1230 // First subtract the adjustment value (which is simply the precomputed value
1231 // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1232 // Then add the minimum value, so the minimum is returned when the density is
1233 // 1. Finally, prevent negative values, which occur when the mean is not 0.5.
1234 const double min = double(min_percent) / 100.0;
1235 const double limit = raw_limit - _dwl_adjustment + min;
1236 return MAX2(limit, 0.0);
1237 }
1238
1239 ParallelCompactData::RegionData*
1240 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1241 const RegionData* end)
1242 {
1243 const size_t region_size = ParallelCompactData::RegionSize;
1244 ParallelCompactData& sd = summary_data();
1245 size_t left = sd.region(beg);
1246 size_t right = end > beg ? sd.region(end) - 1 : left;
1247
1248 // Binary search.
1249 while (left < right) {
1250 // Equivalent to (left + right) / 2, but does not overflow.
1251 const size_t middle = left + (right - left) / 2;
1252 RegionData* const middle_ptr = sd.region(middle);
1253 HeapWord* const dest = middle_ptr->destination();
1254 HeapWord* const addr = sd.region_to_addr(middle);
1255 assert(dest != NULL, "sanity");
1256 assert(dest <= addr, "must move left");
1257
1258 if (middle > left && dest < addr) {
1259 right = middle - 1;
1260 } else if (middle < right && middle_ptr->data_size() == region_size) {
1261 left = middle + 1;
1262 } else {
1263 return middle_ptr;
1264 }
1265 }
1266 return sd.region(left);
1267 }
1268
1269 ParallelCompactData::RegionData*
1270 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1271 const RegionData* end,
1272 size_t dead_words)
1273 {
1274 ParallelCompactData& sd = summary_data();
1275 size_t left = sd.region(beg);
1276 size_t right = end > beg ? sd.region(end) - 1 : left;
1277
1278 // Binary search.
1279 while (left < right) {
1280 // Equivalent to (left + right) / 2, but does not overflow.
1281 const size_t middle = left + (right - left) / 2;
1282 RegionData* const middle_ptr = sd.region(middle);
1283 HeapWord* const dest = middle_ptr->destination();
1284 HeapWord* const addr = sd.region_to_addr(middle);
1285 assert(dest != NULL, "sanity");
1286 assert(dest <= addr, "must move left");
1287
1288 const size_t dead_to_left = pointer_delta(addr, dest);
1289 if (middle > left && dead_to_left > dead_words) {
1290 right = middle - 1;
1291 } else if (middle < right && dead_to_left < dead_words) {
1292 left = middle + 1;
1293 } else {
1294 return middle_ptr;
1295 }
1296 }
1297 return sd.region(left);
1298 }
1299
1300 // The result is valid during the summary phase, after the initial summarization
1301 // of each space into itself, and before final summarization.
1302 inline double
1303 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1304 HeapWord* const bottom,
1305 HeapWord* const top,
1306 HeapWord* const new_top)
1307 {
1308 ParallelCompactData& sd = summary_data();
1309
1310 assert(cp != NULL, "sanity");
1311 assert(bottom != NULL, "sanity");
1312 assert(top != NULL, "sanity");
1313 assert(new_top != NULL, "sanity");
1314 assert(top >= new_top, "summary data problem?");
1315 assert(new_top > bottom, "space is empty; should not be here");
1316 assert(new_top >= cp->destination(), "sanity");
1317 assert(top >= sd.region_to_addr(cp), "sanity");
1318
1319 HeapWord* const destination = cp->destination();
1320 const size_t dense_prefix_live = pointer_delta(destination, bottom);
1321 const size_t compacted_region_live = pointer_delta(new_top, destination);
1322 const size_t compacted_region_used = pointer_delta(top,
1323 sd.region_to_addr(cp));
1324 const size_t reclaimable = compacted_region_used - compacted_region_live;
1325
1326 const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1327 return double(reclaimable) / divisor;
1328 }
1329
1330 // Return the address of the end of the dense prefix, a.k.a. the start of the
1331 // compacted region. The address is always on a region boundary.
1332 //
1333 // Completely full regions at the left are skipped, since no compaction can
1334 // occur in those regions. Then the maximum amount of dead wood to allow is
1335 // computed, based on the density (amount live / capacity) of the generation;
1336 // the region with approximately that amount of dead space to the left is
1337 // identified as the limit region. Regions between the last completely full
1338 // region and the limit region are scanned and the one that has the best
1339 // (maximum) reclaimed_ratio() is selected.
1340 HeapWord*
1341 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1342 bool maximum_compaction)
1343 {
1344 const size_t region_size = ParallelCompactData::RegionSize;
1345 const ParallelCompactData& sd = summary_data();
1346
1347 const MutableSpace* const space = _space_info[id].space();
1348 HeapWord* const top = space->top();
1349 HeapWord* const top_aligned_up = sd.region_align_up(top);
1350 HeapWord* const new_top = _space_info[id].new_top();
1351 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1352 HeapWord* const bottom = space->bottom();
1353 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1354 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1355 const RegionData* const new_top_cp =
1356 sd.addr_to_region_ptr(new_top_aligned_up);
1357
1358 // Skip full regions at the beginning of the space--they are necessarily part
1359 // of the dense prefix.
1360 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1361 assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1362 space->is_empty(), "no dead space allowed to the left");
1363 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1364 "region must have dead space");
1365
1366 // The gc number is saved whenever a maximum compaction is done, and used to
1367 // determine when the maximum compaction interval has expired. This avoids
1368 // successive max compactions for different reasons.
1369 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1370 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1371 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1372 total_invocations() == HeapFirstMaximumCompactionCount;
1373 if (maximum_compaction || full_cp == top_cp || interval_ended) {
1374 _maximum_compaction_gc_num = total_invocations();
1375 return sd.region_to_addr(full_cp);
1376 }
1377
1378 const size_t space_live = pointer_delta(new_top, bottom);
1379 const size_t space_used = space->used_in_words();
1380 const size_t space_capacity = space->capacity_in_words();
1381
1382 const double density = double(space_live) / double(space_capacity);
1383 const size_t min_percent_free = MarkSweepDeadRatio;
1384 const double limiter = dead_wood_limiter(density, min_percent_free);
1385 const size_t dead_wood_max = space_used - space_live;
1386 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1387 dead_wood_max);
1388
1389 if (TraceParallelOldGCDensePrefix) {
1390 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1391 "space_cap=" SIZE_FORMAT,
1392 space_live, space_used,
1393 space_capacity);
1394 tty->print_cr("dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f "
1395 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1396 density, min_percent_free, limiter,
1397 dead_wood_max, dead_wood_limit);
1398 }
1399
1400 // Locate the region with the desired amount of dead space to the left.
1401 const RegionData* const limit_cp =
1402 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1403
1404 // Scan from the first region with dead space to the limit region and find the
1405 // one with the best (largest) reclaimed ratio.
1406 double best_ratio = 0.0;
1407 const RegionData* best_cp = full_cp;
1408 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1409 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1410 if (tmp_ratio > best_ratio) {
1411 best_cp = cp;
1412 best_ratio = tmp_ratio;
1413 }
1414 }
1415
1416 return sd.region_to_addr(best_cp);
1417 }
1418
1419 void PSParallelCompact::summarize_spaces_quick()
1420 {
1421 for (unsigned int i = 0; i < last_space_id; ++i) {
1422 const MutableSpace* space = _space_info[i].space();
1423 HeapWord** nta = _space_info[i].new_top_addr();
1424 bool result = _summary_data.summarize(_space_info[i].split_info(),
1425 space->bottom(), space->top(), NULL,
1426 space->bottom(), space->end(), nta);
1427 assert(result, "space must fit into itself");
1428 _space_info[i].set_dense_prefix(space->bottom());
1429 }
1430 }
1431
1432 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1433 {
1434 HeapWord* const dense_prefix_end = dense_prefix(id);
1435 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1436 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1437 if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1438 // Only enough dead space is filled so that any remaining dead space to the
1439 // left is larger than the minimum filler object. (The remainder is filled
1440 // during the copy/update phase.)
1441 //
1442 // The size of the dead space to the right of the boundary is not a
1443 // concern, since compaction will be able to use whatever space is
1444 // available.
1445 //
1446 // Here '||' is the boundary, 'x' represents a don't care bit and a box
1447 // surrounds the space to be filled with an object.
1448 //
1449 // In the 32-bit VM, each bit represents two 32-bit words:
1450 // +---+
1451 // a) beg_bits: ... x x x | 0 | || 0 x x ...
1452 // end_bits: ... x x x | 0 | || 0 x x ...
1453 // +---+
1454 //
1455 // In the 64-bit VM, each bit represents one 64-bit word:
1456 // +------------+
1457 // b) beg_bits: ... x x x | 0 || 0 | x x ...
1458 // end_bits: ... x x 1 | 0 || 0 | x x ...
1459 // +------------+
1460 // +-------+
1461 // c) beg_bits: ... x x | 0 0 | || 0 x x ...
1462 // end_bits: ... x 1 | 0 0 | || 0 x x ...
1463 // +-------+
1464 // +-----------+
1465 // d) beg_bits: ... x | 0 0 0 | || 0 x x ...
1466 // end_bits: ... 1 | 0 0 0 | || 0 x x ...
1467 // +-----------+
1468 // +-------+
1469 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ...
1470 // end_bits: ... 0 0 | 0 0 | || 0 x x ...
1471 // +-------+
1472
1473 // Initially assume case a, c or e will apply.
1474 size_t obj_len = CollectedHeap::min_fill_size();
1475 HeapWord* obj_beg = dense_prefix_end - obj_len;
1476
1477 #ifdef _LP64
1478 if (MinObjAlignment > 1) { // object alignment > heap word size
1479 // Cases a, c or e.
1480 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1481 // Case b above.
1482 obj_beg = dense_prefix_end - 1;
1483 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1484 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1485 // Case d above.
1486 obj_beg = dense_prefix_end - 3;
1487 obj_len = 3;
1488 }
1489 #endif // #ifdef _LP64
1490
1491 CollectedHeap::fill_with_object(obj_beg, obj_len);
1492 _mark_bitmap.mark_obj(obj_beg, obj_len);
1493 _summary_data.add_obj(obj_beg, obj_len);
1494 assert(start_array(id) != NULL, "sanity");
1495 start_array(id)->allocate_block(obj_beg);
1496 }
1497 }
1498
1499 void
1500 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1501 {
1502 assert(id < last_space_id, "id out of range");
1503 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(),
1504 "should have been reset in summarize_spaces_quick()");
1505
1506 const MutableSpace* space = _space_info[id].space();
1507 if (_space_info[id].new_top() != space->bottom()) {
1508 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1509 _space_info[id].set_dense_prefix(dense_prefix_end);
1510
1511 #ifndef PRODUCT
1512 if (TraceParallelOldGCDensePrefix) {
1513 print_dense_prefix_stats("ratio", id, maximum_compaction,
1514 dense_prefix_end);
1515 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1516 print_dense_prefix_stats("density", id, maximum_compaction, addr);
1517 }
1518 #endif // #ifndef PRODUCT
1519
1520 // Recompute the summary data, taking into account the dense prefix. If
1521 // every last byte will be reclaimed, then the existing summary data which
1522 // compacts everything can be left in place.
1523 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1524 // If dead space crosses the dense prefix boundary, it is (at least
1525 // partially) filled with a dummy object, marked live and added to the
1526 // summary data. This simplifies the copy/update phase and must be done
1527 // before the final locations of objects are determined, to prevent
1528 // leaving a fragment of dead space that is too small to fill.
1529 fill_dense_prefix_end(id);
1530
1531 // Compute the destination of each Region, and thus each object.
1532 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1533 _summary_data.summarize(_space_info[id].split_info(),
1534 dense_prefix_end, space->top(), NULL,
1535 dense_prefix_end, space->end(),
1536 _space_info[id].new_top_addr());
1537 }
1538 }
1539
1540 if (log_develop_is_enabled(Trace, gc, compaction)) {
1541 const size_t region_size = ParallelCompactData::RegionSize;
1542 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1543 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1544 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1545 HeapWord* const new_top = _space_info[id].new_top();
1546 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1547 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1548 log_develop_trace(gc, compaction)(
1549 "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1550 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1551 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1552 id, space->capacity_in_words(), p2i(dense_prefix_end),
1553 dp_region, dp_words / region_size,
1554 cr_words / region_size, p2i(new_top));
1555 }
1556 }
1557
1558 #ifndef PRODUCT
1559 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1560 HeapWord* dst_beg, HeapWord* dst_end,
1561 SpaceId src_space_id,
1562 HeapWord* src_beg, HeapWord* src_end)
1563 {
1564 log_develop_trace(gc, compaction)(
1565 "Summarizing %d [%s] into %d [%s]: "
1566 "src=" PTR_FORMAT "-" PTR_FORMAT " "
1567 SIZE_FORMAT "-" SIZE_FORMAT " "
1568 "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1569 SIZE_FORMAT "-" SIZE_FORMAT,
1570 src_space_id, space_names[src_space_id],
1571 dst_space_id, space_names[dst_space_id],
1572 p2i(src_beg), p2i(src_end),
1573 _summary_data.addr_to_region_idx(src_beg),
1574 _summary_data.addr_to_region_idx(src_end),
1575 p2i(dst_beg), p2i(dst_end),
1576 _summary_data.addr_to_region_idx(dst_beg),
1577 _summary_data.addr_to_region_idx(dst_end));
1578 }
1579 #endif // #ifndef PRODUCT
1580
1581 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1582 bool maximum_compaction)
1583 {
1584 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer);
1585
1586 #ifdef ASSERT
1587 if (TraceParallelOldGCMarkingPhase) {
1588 tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1589 "add_obj_bytes=" SIZE_FORMAT,
1590 add_obj_count, add_obj_size * HeapWordSize);
1591 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1592 "mark_bitmap_bytes=" SIZE_FORMAT,
1593 mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1594 }
1595 #endif // #ifdef ASSERT
1596
1597 // Quick summarization of each space into itself, to see how much is live.
1598 summarize_spaces_quick();
1599
1600 log_develop_trace(gc, compaction)("summary phase: after summarizing each space to self");
1601 NOT_PRODUCT(print_region_ranges());
1602 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1603
1604 // The amount of live data that will end up in old space (assuming it fits).
1605 size_t old_space_total_live = 0;
1606 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1607 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1608 _space_info[id].space()->bottom());
1609 }
1610
1611 MutableSpace* const old_space = _space_info[old_space_id].space();
1612 const size_t old_capacity = old_space->capacity_in_words();
1613 if (old_space_total_live > old_capacity) {
1614 // XXX - should also try to expand
1615 maximum_compaction = true;
1616 }
1617
1618 // Old generations.
1619 summarize_space(old_space_id, maximum_compaction);
1620
1621 // Summarize the remaining spaces in the young gen. The initial target space
1622 // is the old gen. If a space does not fit entirely into the target, then the
1623 // remainder is compacted into the space itself and that space becomes the new
1624 // target.
1625 SpaceId dst_space_id = old_space_id;
1626 HeapWord* dst_space_end = old_space->end();
1627 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1628 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1629 const MutableSpace* space = _space_info[id].space();
1630 const size_t live = pointer_delta(_space_info[id].new_top(),
1631 space->bottom());
1632 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1633
1634 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1635 SpaceId(id), space->bottom(), space->top());)
1636 if (live > 0 && live <= available) {
1637 // All the live data will fit.
1638 bool done = _summary_data.summarize(_space_info[id].split_info(),
1639 space->bottom(), space->top(),
1640 NULL,
1641 *new_top_addr, dst_space_end,
1642 new_top_addr);
1643 assert(done, "space must fit into old gen");
1644
1645 // Reset the new_top value for the space.
1646 _space_info[id].set_new_top(space->bottom());
1647 } else if (live > 0) {
1648 // Attempt to fit part of the source space into the target space.
1649 HeapWord* next_src_addr = NULL;
1650 bool done = _summary_data.summarize(_space_info[id].split_info(),
1651 space->bottom(), space->top(),
1652 &next_src_addr,
1653 *new_top_addr, dst_space_end,
1654 new_top_addr);
1655 assert(!done, "space should not fit into old gen");
1656 assert(next_src_addr != NULL, "sanity");
1657
1658 // The source space becomes the new target, so the remainder is compacted
1659 // within the space itself.
1660 dst_space_id = SpaceId(id);
1661 dst_space_end = space->end();
1662 new_top_addr = _space_info[id].new_top_addr();
1663 NOT_PRODUCT(summary_phase_msg(dst_space_id,
1664 space->bottom(), dst_space_end,
1665 SpaceId(id), next_src_addr, space->top());)
1666 done = _summary_data.summarize(_space_info[id].split_info(),
1667 next_src_addr, space->top(),
1668 NULL,
1669 space->bottom(), dst_space_end,
1670 new_top_addr);
1671 assert(done, "space must fit when compacted into itself");
1672 assert(*new_top_addr <= space->top(), "usage should not grow");
1673 }
1674 }
1675
1676 log_develop_trace(gc, compaction)("Summary_phase: after final summarization");
1677 NOT_PRODUCT(print_region_ranges());
1678 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1679 }
1680
1681 // This method should contain all heap-specific policy for invoking a full
1682 // collection. invoke_no_policy() will only attempt to compact the heap; it
1683 // will do nothing further. If we need to bail out for policy reasons, scavenge
1684 // before full gc, or any other specialized behavior, it needs to be added here.
1685 //
1686 // Note that this method should only be called from the vm_thread while at a
1687 // safepoint.
1688 //
1689 // Note that the all_soft_refs_clear flag in the collector policy
1690 // may be true because this method can be called without intervening
1691 // activity. For example when the heap space is tight and full measure
1692 // are being taken to free space.
1693 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1694 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1695 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1696 "should be in vm thread");
1697
1698 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1699 GCCause::Cause gc_cause = heap->gc_cause();
1700 assert(!heap->is_gc_active(), "not reentrant");
1701
1702 PSAdaptiveSizePolicy* policy = heap->size_policy();
1703 IsGCActiveMark mark;
1704
1705 if (ScavengeBeforeFullGC) {
1706 PSScavenge::invoke_no_policy();
1707 }
1708
1709 const bool clear_all_soft_refs =
1710 heap->soft_ref_policy()->should_clear_all_soft_refs();
1711
1712 PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1713 maximum_heap_compaction);
1714 }
1715
1716 // This method contains no policy. You should probably
1717 // be calling invoke() instead.
1718 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1719 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1720 assert(ref_processor() != NULL, "Sanity");
1721
1722 if (GCLocker::check_active_before_gc()) {
1723 return false;
1724 }
1725
1726 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1727
1728 GCIdMark gc_id_mark;
1729 _gc_timer.register_gc_start();
1730 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
1731
1732 TimeStamp marking_start;
1733 TimeStamp compaction_start;
1734 TimeStamp collection_exit;
1735
1736 GCCause::Cause gc_cause = heap->gc_cause();
1737 PSYoungGen* young_gen = heap->young_gen();
1738 PSOldGen* old_gen = heap->old_gen();
1739 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1740
1741 // The scope of casr should end after code that can change
1742 // CollectorPolicy::_should_clear_all_soft_refs.
1743 ClearedAllSoftRefs casr(maximum_heap_compaction,
1744 heap->soft_ref_policy());
1745
1746 if (ZapUnusedHeapArea) {
1747 // Save information needed to minimize mangling
1748 heap->record_gen_tops_before_GC();
1749 }
1750
1751 // Make sure data structures are sane, make the heap parsable, and do other
1752 // miscellaneous bookkeeping.
1753 pre_compact();
1754
1755 PreGCValues pre_gc_values(heap);
1756
1757 // Get the compaction manager reserved for the VM thread.
1758 ParCompactionManager* const vmthread_cm =
1759 ParCompactionManager::manager_array(gc_task_manager()->workers());
1760
1761 {
1762 ResourceMark rm;
1763 HandleMark hm;
1764
1765 // Set the number of GC threads to be used in this collection
1766 gc_task_manager()->set_active_gang();
1767 gc_task_manager()->task_idle_workers();
1768
1769 GCTraceCPUTime tcpu;
1770 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause, true);
1771
1772 heap->pre_full_gc_dump(&_gc_timer);
1773
1774 TraceCollectorStats tcs(counters());
1775 TraceMemoryManagerStats tms(heap->old_gc_manager(), gc_cause);
1776
1777 if (log_is_enabled(Debug, gc, heap, exit)) {
1778 accumulated_time()->start();
1779 }
1780
1781 // Let the size policy know we're starting
1782 size_policy->major_collection_begin();
1783
1784 CodeCache::gc_prologue();
1785
1786 #if COMPILER2_OR_JVMCI
1787 DerivedPointerTable::clear();
1788 #endif
1789
1790 ref_processor()->enable_discovery();
1791 ref_processor()->setup_policy(maximum_heap_compaction);
1792
1793 bool marked_for_unloading = false;
1794
1795 marking_start.update();
1796 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer);
1797
1798 bool max_on_system_gc = UseMaximumCompactionOnSystemGC
1799 && GCCause::is_user_requested_gc(gc_cause);
1800 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
1801
1802 #if COMPILER2_OR_JVMCI
1803 assert(DerivedPointerTable::is_active(), "Sanity");
1804 DerivedPointerTable::set_active(false);
1805 #endif
1806
1807 // adjust_roots() updates Universe::_intArrayKlassObj which is
1808 // needed by the compaction for filling holes in the dense prefix.
1809 adjust_roots(vmthread_cm);
1810
1811 compaction_start.update();
1812 compact();
1813
1814 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
1815 // done before resizing.
1816 post_compact();
1817
1818 // Let the size policy know we're done
1819 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
1820
1821 if (UseAdaptiveSizePolicy) {
1822 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
1823 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
1824 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
1825
1826 // Don't check if the size_policy is ready here. Let
1827 // the size_policy check that internally.
1828 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
1829 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
1830 // Swap the survivor spaces if from_space is empty. The
1831 // resize_young_gen() called below is normally used after
1832 // a successful young GC and swapping of survivor spaces;
1833 // otherwise, it will fail to resize the young gen with
1834 // the current implementation.
1835 if (young_gen->from_space()->is_empty()) {
1836 young_gen->from_space()->clear(SpaceDecorator::Mangle);
1837 young_gen->swap_spaces();
1838 }
1839
1840 // Calculate optimal free space amounts
1841 assert(young_gen->max_size() >
1842 young_gen->from_space()->capacity_in_bytes() +
1843 young_gen->to_space()->capacity_in_bytes(),
1844 "Sizes of space in young gen are out-of-bounds");
1845
1846 size_t young_live = young_gen->used_in_bytes();
1847 size_t eden_live = young_gen->eden_space()->used_in_bytes();
1848 size_t old_live = old_gen->used_in_bytes();
1849 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
1850 size_t max_old_gen_size = old_gen->max_gen_size();
1851 size_t max_eden_size = young_gen->max_size() -
1852 young_gen->from_space()->capacity_in_bytes() -
1853 young_gen->to_space()->capacity_in_bytes();
1854
1855 // Used for diagnostics
1856 size_policy->clear_generation_free_space_flags();
1857
1858 size_policy->compute_generations_free_space(young_live,
1859 eden_live,
1860 old_live,
1861 cur_eden,
1862 max_old_gen_size,
1863 max_eden_size,
1864 true /* full gc*/);
1865
1866 size_policy->check_gc_overhead_limit(young_live,
1867 eden_live,
1868 max_old_gen_size,
1869 max_eden_size,
1870 true /* full gc*/,
1871 gc_cause,
1872 heap->soft_ref_policy());
1873
1874 size_policy->decay_supplemental_growth(true /* full gc*/);
1875
1876 heap->resize_old_gen(
1877 size_policy->calculated_old_free_size_in_bytes());
1878
1879 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
1880 size_policy->calculated_survivor_size_in_bytes());
1881 }
1882
1883 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
1884 }
1885
1886 if (UsePerfData) {
1887 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
1888 counters->update_counters();
1889 counters->update_old_capacity(old_gen->capacity_in_bytes());
1890 counters->update_young_capacity(young_gen->capacity_in_bytes());
1891 }
1892
1893 heap->resize_all_tlabs();
1894
1895 // Resize the metaspace capacity after a collection
1896 MetaspaceGC::compute_new_size();
1897
1898 if (log_is_enabled(Debug, gc, heap, exit)) {
1899 accumulated_time()->stop();
1900 }
1901
1902 young_gen->print_used_change(pre_gc_values.young_gen_used());
1903 old_gen->print_used_change(pre_gc_values.old_gen_used());
1904 MetaspaceUtils::print_metaspace_change(pre_gc_values.metadata_used());
1905
1906 // Track memory usage and detect low memory
1907 MemoryService::track_memory_usage();
1908 heap->update_counters();
1909 gc_task_manager()->release_idle_workers();
1910
1911 heap->post_full_gc_dump(&_gc_timer);
1912 }
1913
1914 #ifdef ASSERT
1915 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
1916 ParCompactionManager* const cm =
1917 ParCompactionManager::manager_array(int(i));
1918 assert(cm->marking_stack()->is_empty(), "should be empty");
1919 assert(cm->region_stack()->is_empty(), "Region stack " SIZE_FORMAT " is not empty", i);
1920 }
1921 #endif // ASSERT
1922
1923 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1924 HandleMark hm; // Discard invalid handles created during verification
1925 Universe::verify("After GC");
1926 }
1927
1928 // Re-verify object start arrays
1929 if (VerifyObjectStartArray &&
1930 VerifyAfterGC) {
1931 old_gen->verify_object_start_array();
1932 }
1933
1934 if (ZapUnusedHeapArea) {
1935 old_gen->object_space()->check_mangled_unused_area_complete();
1936 }
1937
1938 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1939
1940 collection_exit.update();
1941
1942 heap->print_heap_after_gc();
1943 heap->trace_heap_after_gc(&_gc_tracer);
1944
1945 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT,
1946 marking_start.ticks(), compaction_start.ticks(),
1947 collection_exit.ticks());
1948 gc_task_manager()->print_task_time_stamps();
1949
1950 #ifdef TRACESPINNING
1951 ParallelTaskTerminator::print_termination_counts();
1952 #endif
1953
1954 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
1955
1956 _gc_timer.register_gc_end();
1957
1958 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
1959 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
1960
1961 return true;
1962 }
1963
1964 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
1965 PSYoungGen* young_gen,
1966 PSOldGen* old_gen) {
1967 MutableSpace* const eden_space = young_gen->eden_space();
1968 assert(!eden_space->is_empty(), "eden must be non-empty");
1969 assert(young_gen->virtual_space()->alignment() ==
1970 old_gen->virtual_space()->alignment(), "alignments do not match");
1971
1972 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
1973 return false;
1974 }
1975
1976 // Both generations must be completely committed.
1977 if (young_gen->virtual_space()->uncommitted_size() != 0) {
1978 return false;
1979 }
1980 if (old_gen->virtual_space()->uncommitted_size() != 0) {
1981 return false;
1982 }
1983
1984 // Figure out how much to take from eden. Include the average amount promoted
1985 // in the total; otherwise the next young gen GC will simply bail out to a
1986 // full GC.
1987 const size_t alignment = old_gen->virtual_space()->alignment();
1988 const size_t eden_used = eden_space->used_in_bytes();
1989 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
1990 const size_t absorb_size = align_up(eden_used + promoted, alignment);
1991 const size_t eden_capacity = eden_space->capacity_in_bytes();
1992
1993 if (absorb_size >= eden_capacity) {
1994 return false; // Must leave some space in eden.
1995 }
1996
1997 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
1998 if (new_young_size < young_gen->min_gen_size()) {
1999 return false; // Respect young gen minimum size.
2000 }
2001
2002 log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K: "
2003 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2004 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2005 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2006 absorb_size / K,
2007 eden_capacity / K, (eden_capacity - absorb_size) / K,
2008 young_gen->from_space()->used_in_bytes() / K,
2009 young_gen->to_space()->used_in_bytes() / K,
2010 young_gen->capacity_in_bytes() / K, new_young_size / K);
2011
2012 // Fill the unused part of the old gen.
2013 MutableSpace* const old_space = old_gen->object_space();
2014 HeapWord* const unused_start = old_space->top();
2015 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2016
2017 if (unused_words > 0) {
2018 if (unused_words < CollectedHeap::min_fill_size()) {
2019 return false; // If the old gen cannot be filled, must give up.
2020 }
2021 CollectedHeap::fill_with_objects(unused_start, unused_words);
2022 }
2023
2024 // Take the live data from eden and set both top and end in the old gen to
2025 // eden top. (Need to set end because reset_after_change() mangles the region
2026 // from end to virtual_space->high() in debug builds).
2027 HeapWord* const new_top = eden_space->top();
2028 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2029 absorb_size);
2030 young_gen->reset_after_change();
2031 old_space->set_top(new_top);
2032 old_space->set_end(new_top);
2033 old_gen->reset_after_change();
2034
2035 // Update the object start array for the filler object and the data from eden.
2036 ObjectStartArray* const start_array = old_gen->start_array();
2037 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2038 start_array->allocate_block(p);
2039 }
2040
2041 // Could update the promoted average here, but it is not typically updated at
2042 // full GCs and the value to use is unclear. Something like
2043 //
2044 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2045
2046 size_policy->set_bytes_absorbed_from_eden(absorb_size);
2047 return true;
2048 }
2049
2050 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2051 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2052 "shouldn't return NULL");
2053 return ParallelScavengeHeap::gc_task_manager();
2054 }
2055
2056 class PCAddThreadRootsMarkingTaskClosure : public ThreadClosure {
2057 private:
2058 GCTaskQueue* _q;
2059
2060 public:
2061 PCAddThreadRootsMarkingTaskClosure(GCTaskQueue* q) : _q(q) { }
2062 void do_thread(Thread* t) {
2063 _q->enqueue(new ThreadRootsMarkingTask(t));
2064 }
2065 };
2066
2067 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2068 bool maximum_heap_compaction,
2069 ParallelOldTracer *gc_tracer) {
2070 // Recursively traverse all live objects and mark them
2071 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer);
2072
2073 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2074 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2075 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2076 TaskQueueSetSuper* qset = ParCompactionManager::stack_array();
2077 ParallelTaskTerminator terminator(active_gc_threads, qset);
2078
2079 ParCompactionManager::MarkAndPushClosure mark_and_push_closure(cm);
2080 ParCompactionManager::FollowStackClosure follow_stack_closure(cm);
2081
2082 // Need new claim bits before marking starts.
2083 ClassLoaderDataGraph::clear_claimed_marks();
2084
2085 {
2086 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer);
2087
2088 ParallelScavengeHeap::ParStrongRootsScope psrs;
2089
2090 GCTaskQueue* q = GCTaskQueue::create();
2091
2092 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2093 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2094 // We scan the thread roots in parallel
2095 PCAddThreadRootsMarkingTaskClosure cl(q);
2096 Threads::java_threads_and_vm_thread_do(&cl);
2097 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2098 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2099 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2100 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data));
2101 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2102 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2103
2104 if (active_gc_threads > 1) {
2105 for (uint j = 0; j < active_gc_threads; j++) {
2106 q->enqueue(new StealMarkingTask(&terminator));
2107 }
2108 }
2109
2110 gc_task_manager()->execute_and_wait(q);
2111 }
2112
2113 // Process reference objects found during marking
2114 {
2115 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
2116
2117 ReferenceProcessorStats stats;
2118 ReferenceProcessorPhaseTimes pt(&_gc_timer, ref_processor()->max_num_queues());
2119
2120 if (ref_processor()->processing_is_mt()) {
2121 ref_processor()->set_active_mt_degree(active_gc_threads);
2122
2123 RefProcTaskExecutor task_executor;
2124 stats = ref_processor()->process_discovered_references(
2125 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2126 &task_executor, &pt);
2127 } else {
2128 stats = ref_processor()->process_discovered_references(
2129 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
2130 &pt);
2131 }
2132
2133 gc_tracer->report_gc_reference_stats(stats);
2134 pt.print_all_references();
2135 }
2136
2137 // This is the point where the entire marking should have completed.
2138 assert(cm->marking_stacks_empty(), "Marking should have completed");
2139
2140 {
2141 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer);
2142 WeakProcessor::weak_oops_do(is_alive_closure(), &do_nothing_cl);
2143 }
2144
2145 {
2146 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer);
2147
2148 // Follow system dictionary roots and unload classes.
2149 bool purged_class = SystemDictionary::do_unloading(&_gc_timer);
2150
2151 // Unload nmethods.
2152 CodeCache::do_unloading(is_alive_closure(), purged_class);
2153
2154 // Prune dead klasses from subklass/sibling/implementor lists.
2155 Klass::clean_weak_klass_links(purged_class);
2156 }
2157
2158 {
2159 GCTraceTime(Debug, gc, phases) t("Scrub String Table", &_gc_timer);
2160 // Delete entries for dead interned strings.
2161 StringTable::unlink(is_alive_closure());
2162 }
2163
2164 {
2165 GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", &_gc_timer);
2166 // Clean up unreferenced symbols in symbol table.
2167 SymbolTable::unlink();
2168 }
2169
2170 _gc_tracer.report_object_count_after_gc(is_alive_closure());
2171 }
2172
2173 void PSParallelCompact::adjust_roots(ParCompactionManager* cm) {
2174 // Adjust the pointers to reflect the new locations
2175 GCTraceTime(Info, gc, phases) tm("Adjust Roots", &_gc_timer);
2176
2177 // Need new claim bits when tracing through and adjusting pointers.
2178 ClassLoaderDataGraph::clear_claimed_marks();
2179
2180 PSParallelCompact::AdjustPointerClosure oop_closure(cm);
2181
2182 // General strong roots.
2183 Universe::oops_do(&oop_closure);
2184 JNIHandles::oops_do(&oop_closure); // Global (strong) JNI handles
2185 Threads::oops_do(&oop_closure, NULL);
2186 ObjectSynchronizer::oops_do(&oop_closure);
2187 Management::oops_do(&oop_closure);
2188 JvmtiExport::oops_do(&oop_closure);
2189 SystemDictionary::oops_do(&oop_closure);
2190 CLDToOopClosure cld_closure(&oop_closure);
2191 ClassLoaderDataGraph::cld_do(&cld_closure);
2192
2193 // Now adjust pointers in remaining weak roots. (All of which should
2194 // have been cleared if they pointed to non-surviving objects.)
2195 WeakProcessor::oops_do(&oop_closure);
2196
2197 CodeBlobToOopClosure adjust_from_blobs(&oop_closure, CodeBlobToOopClosure::FixRelocations);
2198 CodeCache::blobs_do(&adjust_from_blobs);
2199 AOTLoader::oops_do(&oop_closure);
2200 StringTable::oops_do(&oop_closure);
2201 ref_processor()->weak_oops_do(&oop_closure);
2202 // Roots were visited so references into the young gen in roots
2203 // may have been scanned. Process them also.
2204 // Should the reference processor have a span that excludes
2205 // young gen objects?
2206 PSScavenge::reference_processor()->weak_oops_do(&oop_closure);
2207 }
2208
2209 // Helper class to print 8 region numbers per line and then print the total at the end.
2210 class FillableRegionLogger : public StackObj {
2211 private:
2212 Log(gc, compaction) log;
2213 static const int LineLength = 8;
2214 size_t _regions[LineLength];
2215 int _next_index;
2216 bool _enabled;
2217 size_t _total_regions;
2218 public:
2219 FillableRegionLogger() : _next_index(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)), _total_regions(0) { }
2220 ~FillableRegionLogger() {
2221 log.trace(SIZE_FORMAT " initially fillable regions", _total_regions);
2222 }
2223
2224 void print_line() {
2225 if (!_enabled || _next_index == 0) {
2226 return;
2227 }
2228 FormatBuffer<> line("Fillable: ");
2229 for (int i = 0; i < _next_index; i++) {
2230 line.append(" " SIZE_FORMAT_W(7), _regions[i]);
2231 }
2232 log.trace("%s", line.buffer());
2233 _next_index = 0;
2234 }
2235
2236 void handle(size_t region) {
2237 if (!_enabled) {
2238 return;
2239 }
2240 _regions[_next_index++] = region;
2241 if (_next_index == LineLength) {
2242 print_line();
2243 }
2244 _total_regions++;
2245 }
2246 };
2247
2248 void PSParallelCompact::prepare_region_draining_tasks(GCTaskQueue* q,
2249 uint parallel_gc_threads)
2250 {
2251 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer);
2252
2253 // Find the threads that are active
2254 unsigned int which = 0;
2255
2256 // Find all regions that are available (can be filled immediately) and
2257 // distribute them to the thread stacks. The iteration is done in reverse
2258 // order (high to low) so the regions will be removed in ascending order.
2259
2260 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2261
2262 which = 0;
2263 // id + 1 is used to test termination so unsigned can
2264 // be used with an old_space_id == 0.
2265 FillableRegionLogger region_logger;
2266 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2267 SpaceInfo* const space_info = _space_info + id;
2268 MutableSpace* const space = space_info->space();
2269 HeapWord* const new_top = space_info->new_top();
2270
2271 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2272 const size_t end_region =
2273 sd.addr_to_region_idx(sd.region_align_up(new_top));
2274
2275 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2276 if (sd.region(cur)->claim_unsafe()) {
2277 ParCompactionManager* cm = ParCompactionManager::manager_array(which);
2278 cm->region_stack()->push(cur);
2279 region_logger.handle(cur);
2280 // Assign regions to tasks in round-robin fashion.
2281 if (++which == parallel_gc_threads) {
2282 which = 0;
2283 }
2284 }
2285 }
2286 region_logger.print_line();
2287 }
2288 }
2289
2290 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2291
2292 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2293 uint parallel_gc_threads) {
2294 GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer);
2295
2296 ParallelCompactData& sd = PSParallelCompact::summary_data();
2297
2298 // Iterate over all the spaces adding tasks for updating
2299 // regions in the dense prefix. Assume that 1 gc thread
2300 // will work on opening the gaps and the remaining gc threads
2301 // will work on the dense prefix.
2302 unsigned int space_id;
2303 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2304 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2305 const MutableSpace* const space = _space_info[space_id].space();
2306
2307 if (dense_prefix_end == space->bottom()) {
2308 // There is no dense prefix for this space.
2309 continue;
2310 }
2311
2312 // The dense prefix is before this region.
2313 size_t region_index_end_dense_prefix =
2314 sd.addr_to_region_idx(dense_prefix_end);
2315 RegionData* const dense_prefix_cp =
2316 sd.region(region_index_end_dense_prefix);
2317 assert(dense_prefix_end == space->end() ||
2318 dense_prefix_cp->available() ||
2319 dense_prefix_cp->claimed(),
2320 "The region after the dense prefix should always be ready to fill");
2321
2322 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2323
2324 // Is there dense prefix work?
2325 size_t total_dense_prefix_regions =
2326 region_index_end_dense_prefix - region_index_start;
2327 // How many regions of the dense prefix should be given to
2328 // each thread?
2329 if (total_dense_prefix_regions > 0) {
2330 uint tasks_for_dense_prefix = 1;
2331 if (total_dense_prefix_regions <=
2332 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2333 // Don't over partition. This assumes that
2334 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2335 // so there are not many regions to process.
2336 tasks_for_dense_prefix = parallel_gc_threads;
2337 } else {
2338 // Over partition
2339 tasks_for_dense_prefix = parallel_gc_threads *
2340 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2341 }
2342 size_t regions_per_thread = total_dense_prefix_regions /
2343 tasks_for_dense_prefix;
2344 // Give each thread at least 1 region.
2345 if (regions_per_thread == 0) {
2346 regions_per_thread = 1;
2347 }
2348
2349 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2350 if (region_index_start >= region_index_end_dense_prefix) {
2351 break;
2352 }
2353 // region_index_end is not processed
2354 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2355 region_index_end_dense_prefix);
2356 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2357 region_index_start,
2358 region_index_end));
2359 region_index_start = region_index_end;
2360 }
2361 }
2362 // This gets any part of the dense prefix that did not
2363 // fit evenly.
2364 if (region_index_start < region_index_end_dense_prefix) {
2365 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2366 region_index_start,
2367 region_index_end_dense_prefix));
2368 }
2369 }
2370 }
2371
2372 void PSParallelCompact::enqueue_region_stealing_tasks(
2373 GCTaskQueue* q,
2374 ParallelTaskTerminator* terminator_ptr,
2375 uint parallel_gc_threads) {
2376 GCTraceTime(Trace, gc, phases) tm("Steal Task Setup", &_gc_timer);
2377
2378 // Once a thread has drained it's stack, it should try to steal regions from
2379 // other threads.
2380 for (uint j = 0; j < parallel_gc_threads; j++) {
2381 q->enqueue(new CompactionWithStealingTask(terminator_ptr));
2382 }
2383 }
2384
2385 #ifdef ASSERT
2386 // Write a histogram of the number of times the block table was filled for a
2387 // region.
2388 void PSParallelCompact::write_block_fill_histogram()
2389 {
2390 if (!log_develop_is_enabled(Trace, gc, compaction)) {
2391 return;
2392 }
2393
2394 Log(gc, compaction) log;
2395 ResourceMark rm;
2396 LogStream ls(log.trace());
2397 outputStream* out = &ls;
2398
2399 typedef ParallelCompactData::RegionData rd_t;
2400 ParallelCompactData& sd = summary_data();
2401
2402 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2403 MutableSpace* const spc = _space_info[id].space();
2404 if (spc->bottom() != spc->top()) {
2405 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
2406 HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
2407 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
2408
2409 size_t histo[5] = { 0, 0, 0, 0, 0 };
2410 const size_t histo_len = sizeof(histo) / sizeof(size_t);
2411 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
2412
2413 for (const rd_t* cur = beg; cur < end; ++cur) {
2414 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
2415 }
2416 out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
2417 for (size_t i = 0; i < histo_len; ++i) {
2418 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
2419 histo[i], 100.0 * histo[i] / region_cnt);
2420 }
2421 out->cr();
2422 }
2423 }
2424 }
2425 #endif // #ifdef ASSERT
2426
2427 void PSParallelCompact::compact() {
2428 GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer);
2429
2430 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2431 PSOldGen* old_gen = heap->old_gen();
2432 old_gen->start_array()->reset();
2433 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2434 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2435 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2436 ParallelTaskTerminator terminator(active_gc_threads, qset);
2437
2438 GCTaskQueue* q = GCTaskQueue::create();
2439 prepare_region_draining_tasks(q, active_gc_threads);
2440 enqueue_dense_prefix_tasks(q, active_gc_threads);
2441 enqueue_region_stealing_tasks(q, &terminator, active_gc_threads);
2442
2443 {
2444 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer);
2445
2446 gc_task_manager()->execute_and_wait(q);
2447
2448 #ifdef ASSERT
2449 // Verify that all regions have been processed before the deferred updates.
2450 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2451 verify_complete(SpaceId(id));
2452 }
2453 #endif
2454 }
2455
2456 {
2457 // Update the deferred objects, if any. Any compaction manager can be used.
2458 GCTraceTime(Trace, gc, phases) tm("Deferred Updates", &_gc_timer);
2459 ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2460 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2461 update_deferred_objects(cm, SpaceId(id));
2462 }
2463 }
2464
2465 DEBUG_ONLY(write_block_fill_histogram());
2466 }
2467
2468 #ifdef ASSERT
2469 void PSParallelCompact::verify_complete(SpaceId space_id) {
2470 // All Regions between space bottom() to new_top() should be marked as filled
2471 // and all Regions between new_top() and top() should be available (i.e.,
2472 // should have been emptied).
2473 ParallelCompactData& sd = summary_data();
2474 SpaceInfo si = _space_info[space_id];
2475 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2476 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2477 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2478 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2479 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2480
2481 bool issued_a_warning = false;
2482
2483 size_t cur_region;
2484 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2485 const RegionData* const c = sd.region(cur_region);
2486 if (!c->completed()) {
2487 log_warning(gc)("region " SIZE_FORMAT " not filled: destination_count=%u",
2488 cur_region, c->destination_count());
2489 issued_a_warning = true;
2490 }
2491 }
2492
2493 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2494 const RegionData* const c = sd.region(cur_region);
2495 if (!c->available()) {
2496 log_warning(gc)("region " SIZE_FORMAT " not empty: destination_count=%u",
2497 cur_region, c->destination_count());
2498 issued_a_warning = true;
2499 }
2500 }
2501
2502 if (issued_a_warning) {
2503 print_region_ranges();
2504 }
2505 }
2506 #endif // #ifdef ASSERT
2507
2508 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) {
2509 _start_array->allocate_block(addr);
2510 compaction_manager()->update_contents(oop(addr));
2511 }
2512
2513 // Update interior oops in the ranges of regions [beg_region, end_region).
2514 void
2515 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2516 SpaceId space_id,
2517 size_t beg_region,
2518 size_t end_region) {
2519 ParallelCompactData& sd = summary_data();
2520 ParMarkBitMap* const mbm = mark_bitmap();
2521
2522 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2523 HeapWord* const end_addr = sd.region_to_addr(end_region);
2524 assert(beg_region <= end_region, "bad region range");
2525 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2526
2527 #ifdef ASSERT
2528 // Claim the regions to avoid triggering an assert when they are marked as
2529 // filled.
2530 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2531 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2532 }
2533 #endif // #ifdef ASSERT
2534
2535 if (beg_addr != space(space_id)->bottom()) {
2536 // Find the first live object or block of dead space that *starts* in this
2537 // range of regions. If a partial object crosses onto the region, skip it;
2538 // it will be marked for 'deferred update' when the object head is
2539 // processed. If dead space crosses onto the region, it is also skipped; it
2540 // will be filled when the prior region is processed. If neither of those
2541 // apply, the first word in the region is the start of a live object or dead
2542 // space.
2543 assert(beg_addr > space(space_id)->bottom(), "sanity");
2544 const RegionData* const cp = sd.region(beg_region);
2545 if (cp->partial_obj_size() != 0) {
2546 beg_addr = sd.partial_obj_end(beg_region);
2547 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2548 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2549 }
2550 }
2551
2552 if (beg_addr < end_addr) {
2553 // A live object or block of dead space starts in this range of Regions.
2554 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2555
2556 // Create closures and iterate.
2557 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2558 FillClosure fill_closure(cm, space_id);
2559 ParMarkBitMap::IterationStatus status;
2560 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2561 dense_prefix_end);
2562 if (status == ParMarkBitMap::incomplete) {
2563 update_closure.do_addr(update_closure.source());
2564 }
2565 }
2566
2567 // Mark the regions as filled.
2568 RegionData* const beg_cp = sd.region(beg_region);
2569 RegionData* const end_cp = sd.region(end_region);
2570 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2571 cp->set_completed();
2572 }
2573 }
2574
2575 // Return the SpaceId for the space containing addr. If addr is not in the
2576 // heap, last_space_id is returned. In debug mode it expects the address to be
2577 // in the heap and asserts such.
2578 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2579 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
2580
2581 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2582 if (_space_info[id].space()->contains(addr)) {
2583 return SpaceId(id);
2584 }
2585 }
2586
2587 assert(false, "no space contains the addr");
2588 return last_space_id;
2589 }
2590
2591 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2592 SpaceId id) {
2593 assert(id < last_space_id, "bad space id");
2594
2595 ParallelCompactData& sd = summary_data();
2596 const SpaceInfo* const space_info = _space_info + id;
2597 ObjectStartArray* const start_array = space_info->start_array();
2598
2599 const MutableSpace* const space = space_info->space();
2600 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2601 HeapWord* const beg_addr = space_info->dense_prefix();
2602 HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2603
2604 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2605 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2606 const RegionData* cur_region;
2607 for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2608 HeapWord* const addr = cur_region->deferred_obj_addr();
2609 if (addr != NULL) {
2610 if (start_array != NULL) {
2611 start_array->allocate_block(addr);
2612 }
2613 cm->update_contents(oop(addr));
2614 assert(oopDesc::is_oop_or_null(oop(addr)), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(addr)));
2615 }
2616 }
2617 }
2618
2619 // Skip over count live words starting from beg, and return the address of the
2620 // next live word. Unless marked, the word corresponding to beg is assumed to
2621 // be dead. Callers must either ensure beg does not correspond to the middle of
2622 // an object, or account for those live words in some other way. Callers must
2623 // also ensure that there are enough live words in the range [beg, end) to skip.
2624 HeapWord*
2625 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2626 {
2627 assert(count > 0, "sanity");
2628
2629 ParMarkBitMap* m = mark_bitmap();
2630 idx_t bits_to_skip = m->words_to_bits(count);
2631 idx_t cur_beg = m->addr_to_bit(beg);
2632 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
2633
2634 do {
2635 cur_beg = m->find_obj_beg(cur_beg, search_end);
2636 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2637 const size_t obj_bits = cur_end - cur_beg + 1;
2638 if (obj_bits > bits_to_skip) {
2639 return m->bit_to_addr(cur_beg + bits_to_skip);
2640 }
2641 bits_to_skip -= obj_bits;
2642 cur_beg = cur_end + 1;
2643 } while (bits_to_skip > 0);
2644
2645 // Skipping the desired number of words landed just past the end of an object.
2646 // Find the start of the next object.
2647 cur_beg = m->find_obj_beg(cur_beg, search_end);
2648 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2649 return m->bit_to_addr(cur_beg);
2650 }
2651
2652 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2653 SpaceId src_space_id,
2654 size_t src_region_idx)
2655 {
2656 assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2657
2658 const SplitInfo& split_info = _space_info[src_space_id].split_info();
2659 if (split_info.dest_region_addr() == dest_addr) {
2660 // The partial object ending at the split point contains the first word to
2661 // be copied to dest_addr.
2662 return split_info.first_src_addr();
2663 }
2664
2665 const ParallelCompactData& sd = summary_data();
2666 ParMarkBitMap* const bitmap = mark_bitmap();
2667 const size_t RegionSize = ParallelCompactData::RegionSize;
2668
2669 assert(sd.is_region_aligned(dest_addr), "not aligned");
2670 const RegionData* const src_region_ptr = sd.region(src_region_idx);
2671 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2672 HeapWord* const src_region_destination = src_region_ptr->destination();
2673
2674 assert(dest_addr >= src_region_destination, "wrong src region");
2675 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2676
2677 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2678 HeapWord* const src_region_end = src_region_beg + RegionSize;
2679
2680 HeapWord* addr = src_region_beg;
2681 if (dest_addr == src_region_destination) {
2682 // Return the first live word in the source region.
2683 if (partial_obj_size == 0) {
2684 addr = bitmap->find_obj_beg(addr, src_region_end);
2685 assert(addr < src_region_end, "no objects start in src region");
2686 }
2687 return addr;
2688 }
2689
2690 // Must skip some live data.
2691 size_t words_to_skip = dest_addr - src_region_destination;
2692 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2693
2694 if (partial_obj_size >= words_to_skip) {
2695 // All the live words to skip are part of the partial object.
2696 addr += words_to_skip;
2697 if (partial_obj_size == words_to_skip) {
2698 // Find the first live word past the partial object.
2699 addr = bitmap->find_obj_beg(addr, src_region_end);
2700 assert(addr < src_region_end, "wrong src region");
2701 }
2702 return addr;
2703 }
2704
2705 // Skip over the partial object (if any).
2706 if (partial_obj_size != 0) {
2707 words_to_skip -= partial_obj_size;
2708 addr += partial_obj_size;
2709 }
2710
2711 // Skip over live words due to objects that start in the region.
2712 addr = skip_live_words(addr, src_region_end, words_to_skip);
2713 assert(addr < src_region_end, "wrong src region");
2714 return addr;
2715 }
2716
2717 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2718 SpaceId src_space_id,
2719 size_t beg_region,
2720 HeapWord* end_addr)
2721 {
2722 ParallelCompactData& sd = summary_data();
2723
2724 #ifdef ASSERT
2725 MutableSpace* const src_space = _space_info[src_space_id].space();
2726 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2727 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2728 "src_space_id does not match beg_addr");
2729 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2730 "src_space_id does not match end_addr");
2731 #endif // #ifdef ASSERT
2732
2733 RegionData* const beg = sd.region(beg_region);
2734 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2735
2736 // Regions up to new_top() are enqueued if they become available.
2737 HeapWord* const new_top = _space_info[src_space_id].new_top();
2738 RegionData* const enqueue_end =
2739 sd.addr_to_region_ptr(sd.region_align_up(new_top));
2740
2741 for (RegionData* cur = beg; cur < end; ++cur) {
2742 assert(cur->data_size() > 0, "region must have live data");
2743 cur->decrement_destination_count();
2744 if (cur < enqueue_end && cur->available() && cur->claim()) {
2745 cm->push_region(sd.region(cur));
2746 }
2747 }
2748 }
2749
2750 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2751 SpaceId& src_space_id,
2752 HeapWord*& src_space_top,
2753 HeapWord* end_addr)
2754 {
2755 typedef ParallelCompactData::RegionData RegionData;
2756
2757 ParallelCompactData& sd = PSParallelCompact::summary_data();
2758 const size_t region_size = ParallelCompactData::RegionSize;
2759
2760 size_t src_region_idx = 0;
2761
2762 // Skip empty regions (if any) up to the top of the space.
2763 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2764 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2765 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2766 const RegionData* const top_region_ptr =
2767 sd.addr_to_region_ptr(top_aligned_up);
2768 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2769 ++src_region_ptr;
2770 }
2771
2772 if (src_region_ptr < top_region_ptr) {
2773 // The next source region is in the current space. Update src_region_idx
2774 // and the source address to match src_region_ptr.
2775 src_region_idx = sd.region(src_region_ptr);
2776 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
2777 if (src_region_addr > closure.source()) {
2778 closure.set_source(src_region_addr);
2779 }
2780 return src_region_idx;
2781 }
2782
2783 // Switch to a new source space and find the first non-empty region.
2784 unsigned int space_id = src_space_id + 1;
2785 assert(space_id < last_space_id, "not enough spaces");
2786
2787 HeapWord* const destination = closure.destination();
2788
2789 do {
2790 MutableSpace* space = _space_info[space_id].space();
2791 HeapWord* const bottom = space->bottom();
2792 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
2793
2794 // Iterate over the spaces that do not compact into themselves.
2795 if (bottom_cp->destination() != bottom) {
2796 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
2797 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
2798
2799 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
2800 if (src_cp->live_obj_size() > 0) {
2801 // Found it.
2802 assert(src_cp->destination() == destination,
2803 "first live obj in the space must match the destination");
2804 assert(src_cp->partial_obj_size() == 0,
2805 "a space cannot begin with a partial obj");
2806
2807 src_space_id = SpaceId(space_id);
2808 src_space_top = space->top();
2809 const size_t src_region_idx = sd.region(src_cp);
2810 closure.set_source(sd.region_to_addr(src_region_idx));
2811 return src_region_idx;
2812 } else {
2813 assert(src_cp->data_size() == 0, "sanity");
2814 }
2815 }
2816 }
2817 } while (++space_id < last_space_id);
2818
2819 assert(false, "no source region was found");
2820 return 0;
2821 }
2822
2823 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
2824 {
2825 typedef ParMarkBitMap::IterationStatus IterationStatus;
2826 const size_t RegionSize = ParallelCompactData::RegionSize;
2827 ParMarkBitMap* const bitmap = mark_bitmap();
2828 ParallelCompactData& sd = summary_data();
2829 RegionData* const region_ptr = sd.region(region_idx);
2830
2831 // Get the items needed to construct the closure.
2832 HeapWord* dest_addr = sd.region_to_addr(region_idx);
2833 SpaceId dest_space_id = space_id(dest_addr);
2834 ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
2835 HeapWord* new_top = _space_info[dest_space_id].new_top();
2836 assert(dest_addr < new_top, "sanity");
2837 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
2838
2839 // Get the source region and related info.
2840 size_t src_region_idx = region_ptr->source_region();
2841 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2842 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2843
2844 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
2845 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2846
2847 // Adjust src_region_idx to prepare for decrementing destination counts (the
2848 // destination count is not decremented when a region is copied to itself).
2849 if (src_region_idx == region_idx) {
2850 src_region_idx += 1;
2851 }
2852
2853 if (bitmap->is_unmarked(closure.source())) {
2854 // The first source word is in the middle of an object; copy the remainder
2855 // of the object or as much as will fit. The fact that pointer updates were
2856 // deferred will be noted when the object header is processed.
2857 HeapWord* const old_src_addr = closure.source();
2858 closure.copy_partial_obj();
2859 if (closure.is_full()) {
2860 decrement_destination_counts(cm, src_space_id, src_region_idx,
2861 closure.source());
2862 region_ptr->set_deferred_obj_addr(NULL);
2863 region_ptr->set_completed();
2864 return;
2865 }
2866
2867 HeapWord* const end_addr = sd.region_align_down(closure.source());
2868 if (sd.region_align_down(old_src_addr) != end_addr) {
2869 // The partial object was copied from more than one source region.
2870 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2871
2872 // Move to the next source region, possibly switching spaces as well. All
2873 // args except end_addr may be modified.
2874 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2875 end_addr);
2876 }
2877 }
2878
2879 do {
2880 HeapWord* const cur_addr = closure.source();
2881 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2882 src_space_top);
2883 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
2884
2885 if (status == ParMarkBitMap::incomplete) {
2886 // The last obj that starts in the source region does not end in the
2887 // region.
2888 assert(closure.source() < end_addr, "sanity");
2889 HeapWord* const obj_beg = closure.source();
2890 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
2891 src_space_top);
2892 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
2893 if (obj_end < range_end) {
2894 // The end was found; the entire object will fit.
2895 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
2896 assert(status != ParMarkBitMap::would_overflow, "sanity");
2897 } else {
2898 // The end was not found; the object will not fit.
2899 assert(range_end < src_space_top, "obj cannot cross space boundary");
2900 status = ParMarkBitMap::would_overflow;
2901 }
2902 }
2903
2904 if (status == ParMarkBitMap::would_overflow) {
2905 // The last object did not fit. Note that interior oop updates were
2906 // deferred, then copy enough of the object to fill the region.
2907 region_ptr->set_deferred_obj_addr(closure.destination());
2908 status = closure.copy_until_full(); // copies from closure.source()
2909
2910 decrement_destination_counts(cm, src_space_id, src_region_idx,
2911 closure.source());
2912 region_ptr->set_completed();
2913 return;
2914 }
2915
2916 if (status == ParMarkBitMap::full) {
2917 decrement_destination_counts(cm, src_space_id, src_region_idx,
2918 closure.source());
2919 region_ptr->set_deferred_obj_addr(NULL);
2920 region_ptr->set_completed();
2921 return;
2922 }
2923
2924 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2925
2926 // Move to the next source region, possibly switching spaces as well. All
2927 // args except end_addr may be modified.
2928 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2929 end_addr);
2930 } while (true);
2931 }
2932
2933 void PSParallelCompact::fill_blocks(size_t region_idx)
2934 {
2935 // Fill in the block table elements for the specified region. Each block
2936 // table element holds the number of live words in the region that are to the
2937 // left of the first object that starts in the block. Thus only blocks in
2938 // which an object starts need to be filled.
2939 //
2940 // The algorithm scans the section of the bitmap that corresponds to the
2941 // region, keeping a running total of the live words. When an object start is
2942 // found, if it's the first to start in the block that contains it, the
2943 // current total is written to the block table element.
2944 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
2945 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
2946 const size_t RegionSize = ParallelCompactData::RegionSize;
2947
2948 ParallelCompactData& sd = summary_data();
2949 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
2950 if (partial_obj_size >= RegionSize) {
2951 return; // No objects start in this region.
2952 }
2953
2954 // Ensure the first loop iteration decides that the block has changed.
2955 size_t cur_block = sd.block_count();
2956
2957 const ParMarkBitMap* const bitmap = mark_bitmap();
2958
2959 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
2960 assert((size_t)1 << Log2BitsPerBlock ==
2961 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
2962
2963 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
2964 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
2965 size_t live_bits = bitmap->words_to_bits(partial_obj_size);
2966 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
2967 while (beg_bit < range_end) {
2968 const size_t new_block = beg_bit >> Log2BitsPerBlock;
2969 if (new_block != cur_block) {
2970 cur_block = new_block;
2971 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
2972 }
2973
2974 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
2975 if (end_bit < range_end - 1) {
2976 live_bits += end_bit - beg_bit + 1;
2977 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
2978 } else {
2979 return;
2980 }
2981 }
2982 }
2983
2984 void
2985 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
2986 const MutableSpace* sp = space(space_id);
2987 if (sp->is_empty()) {
2988 return;
2989 }
2990
2991 ParallelCompactData& sd = PSParallelCompact::summary_data();
2992 ParMarkBitMap* const bitmap = mark_bitmap();
2993 HeapWord* const dp_addr = dense_prefix(space_id);
2994 HeapWord* beg_addr = sp->bottom();
2995 HeapWord* end_addr = sp->top();
2996
2997 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
2998
2999 const size_t beg_region = sd.addr_to_region_idx(beg_addr);
3000 const size_t dp_region = sd.addr_to_region_idx(dp_addr);
3001 if (beg_region < dp_region) {
3002 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
3003 }
3004
3005 // The destination of the first live object that starts in the region is one
3006 // past the end of the partial object entering the region (if any).
3007 HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3008 HeapWord* const new_top = _space_info[space_id].new_top();
3009 assert(new_top >= dest_addr, "bad new_top value");
3010 const size_t words = pointer_delta(new_top, dest_addr);
3011
3012 if (words > 0) {
3013 ObjectStartArray* start_array = _space_info[space_id].start_array();
3014 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3015
3016 ParMarkBitMap::IterationStatus status;
3017 status = bitmap->iterate(&closure, dest_addr, end_addr);
3018 assert(status == ParMarkBitMap::full, "iteration not complete");
3019 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3020 "live objects skipped because closure is full");
3021 }
3022 }
3023
3024 jlong PSParallelCompact::millis_since_last_gc() {
3025 // We need a monotonically non-decreasing time in ms but
3026 // os::javaTimeMillis() does not guarantee monotonicity.
3027 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3028 jlong ret_val = now - _time_of_last_gc;
3029 // XXX See note in genCollectedHeap::millis_since_last_gc().
3030 if (ret_val < 0) {
3031 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);)
3032 return 0;
3033 }
3034 return ret_val;
3035 }
3036
3037 void PSParallelCompact::reset_millis_since_last_gc() {
3038 // We need a monotonically non-decreasing time in ms but
3039 // os::javaTimeMillis() does not guarantee monotonicity.
3040 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3041 }
3042
3043 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3044 {
3045 if (source() != destination()) {
3046 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3047 Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3048 }
3049 update_state(words_remaining());
3050 assert(is_full(), "sanity");
3051 return ParMarkBitMap::full;
3052 }
3053
3054 void MoveAndUpdateClosure::copy_partial_obj()
3055 {
3056 size_t words = words_remaining();
3057
3058 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3059 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3060 if (end_addr < range_end) {
3061 words = bitmap()->obj_size(source(), end_addr);
3062 }
3063
3064 // This test is necessary; if omitted, the pointer updates to a partial object
3065 // that crosses the dense prefix boundary could be overwritten.
3066 if (source() != destination()) {
3067 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3068 Copy::aligned_conjoint_words(source(), destination(), words);
3069 }
3070 update_state(words);
3071 }
3072
3073 void InstanceKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3074 PSParallelCompact::AdjustPointerClosure closure(cm);
3075 if (UseCompressedOops) {
3076 oop_oop_iterate_oop_maps<narrowOop>(obj, &closure);
3077 } else {
3078 oop_oop_iterate_oop_maps<oop>(obj, &closure);
3079 }
3080 }
3081
3082 void InstanceMirrorKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3083 InstanceKlass::oop_pc_update_pointers(obj, cm);
3084
3085 PSParallelCompact::AdjustPointerClosure closure(cm);
3086 if (UseCompressedOops) {
3087 oop_oop_iterate_statics<narrowOop>(obj, &closure);
3088 } else {
3089 oop_oop_iterate_statics<oop>(obj, &closure);
3090 }
3091 }
3092
3093 void InstanceClassLoaderKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3094 InstanceKlass::oop_pc_update_pointers(obj, cm);
3095 }
3096
3097 #ifdef ASSERT
3098 template <class T> static void trace_reference_gc(const char *s, oop obj,
3099 T* referent_addr,
3100 T* discovered_addr) {
3101 log_develop_trace(gc, ref)("%s obj " PTR_FORMAT, s, p2i(obj));
3102 log_develop_trace(gc, ref)(" referent_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3103 p2i(referent_addr), referent_addr ? p2i((oop)RawAccess<>::oop_load(referent_addr)) : NULL);
3104 log_develop_trace(gc, ref)(" discovered_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3105 p2i(discovered_addr), discovered_addr ? p2i((oop)RawAccess<>::oop_load(discovered_addr)) : NULL);
3106 }
3107 #endif
3108
3109 template <class T>
3110 static void oop_pc_update_pointers_specialized(oop obj, ParCompactionManager* cm) {
3111 T* referent_addr = (T*)java_lang_ref_Reference::referent_addr_raw(obj);
3112 PSParallelCompact::adjust_pointer(referent_addr, cm);
3113 T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr_raw(obj);
3114 PSParallelCompact::adjust_pointer(discovered_addr, cm);
3115 debug_only(trace_reference_gc("InstanceRefKlass::oop_update_ptrs", obj,
3116 referent_addr, discovered_addr);)
3117 }
3118
3119 void InstanceRefKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3120 InstanceKlass::oop_pc_update_pointers(obj, cm);
3121
3122 if (UseCompressedOops) {
3123 oop_pc_update_pointers_specialized<narrowOop>(obj, cm);
3124 } else {
3125 oop_pc_update_pointers_specialized<oop>(obj, cm);
3126 }
3127 }
3128
3129 void ObjArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3130 assert(obj->is_objArray(), "obj must be obj array");
3131 PSParallelCompact::AdjustPointerClosure closure(cm);
3132 if (UseCompressedOops) {
3133 oop_oop_iterate_elements<narrowOop>(objArrayOop(obj), &closure);
3134 } else {
3135 oop_oop_iterate_elements<oop>(objArrayOop(obj), &closure);
3136 }
3137 }
3138
3139 void TypeArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3140 assert(obj->is_typeArray(),"must be a type array");
3141 }
3142
3143 ParMarkBitMapClosure::IterationStatus
3144 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3145 assert(destination() != NULL, "sanity");
3146 assert(bitmap()->obj_size(addr) == words, "bad size");
3147
3148 _source = addr;
3149 assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) ==
3150 destination(), "wrong destination");
3151
3152 if (words > words_remaining()) {
3153 return ParMarkBitMap::would_overflow;
3154 }
3155
3156 // The start_array must be updated even if the object is not moving.
3157 if (_start_array != NULL) {
3158 _start_array->allocate_block(destination());
3159 }
3160
3161 if (destination() != source()) {
3162 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3163 Copy::aligned_conjoint_words(source(), destination(), words);
3164 }
3165
3166 oop moved_oop = (oop) destination();
3167 compaction_manager()->update_contents(moved_oop);
3168 assert(oopDesc::is_oop_or_null(moved_oop), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop));
3169
3170 update_state(words);
3171 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3172 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3173 }
3174
3175 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3176 ParCompactionManager* cm,
3177 PSParallelCompact::SpaceId space_id) :
3178 ParMarkBitMapClosure(mbm, cm),
3179 _space_id(space_id),
3180 _start_array(PSParallelCompact::start_array(space_id))
3181 {
3182 }
3183
3184 // Updates the references in the object to their new values.
3185 ParMarkBitMapClosure::IterationStatus
3186 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3187 do_addr(addr);
3188 return ParMarkBitMap::incomplete;
3189 }
3190
3191 FillClosure::FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) :
3192 ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm),
3193 _start_array(PSParallelCompact::start_array(space_id))
3194 {
3195 assert(space_id == PSParallelCompact::old_space_id,
3196 "cannot use FillClosure in the young gen");
3197 }
3198
3199 ParMarkBitMapClosure::IterationStatus
3200 FillClosure::do_addr(HeapWord* addr, size_t size) {
3201 CollectedHeap::fill_with_objects(addr, size);
3202 HeapWord* const end = addr + size;
3203 do {
3204 _start_array->allocate_block(addr);
3205 addr += oop(addr)->size();
3206 } while (addr < end);
3207 return ParMarkBitMap::incomplete;
3208 }