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