1 /*
2 * Copyright (c) 2005, 2016, 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 "classfile/stringTable.hpp"
27 #include "classfile/symbolTable.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "code/codeCache.hpp"
30 #include "gc/parallel/gcTaskManager.hpp"
31 #include "gc/parallel/parallelScavengeHeap.inline.hpp"
32 #include "gc/parallel/pcTasks.hpp"
33 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
34 #include "gc/parallel/psCompactionManager.inline.hpp"
35 #include "gc/parallel/psMarkSweep.hpp"
36 #include "gc/parallel/psMarkSweepDecorator.hpp"
37 #include "gc/parallel/psOldGen.hpp"
38 #include "gc/parallel/psParallelCompact.inline.hpp"
39 #include "gc/parallel/psPromotionManager.inline.hpp"
40 #include "gc/parallel/psScavenge.hpp"
41 #include "gc/parallel/psYoungGen.hpp"
42 #include "gc/shared/gcCause.hpp"
43 #include "gc/shared/gcHeapSummary.hpp"
44 #include "gc/shared/gcId.hpp"
45 #include "gc/shared/gcLocker.inline.hpp"
46 #include "gc/shared/gcTimer.hpp"
47 #include "gc/shared/gcTrace.hpp"
48 #include "gc/shared/gcTraceTime.inline.hpp"
49 #include "gc/shared/isGCActiveMark.hpp"
50 #include "gc/shared/referencePolicy.hpp"
51 #include "gc/shared/referenceProcessor.hpp"
52 #include "gc/shared/spaceDecorator.hpp"
53 #include "logging/log.hpp"
54 #include "memory/resourceArea.hpp"
55 #include "oops/instanceKlass.inline.hpp"
56 #include "oops/instanceMirrorKlass.inline.hpp"
57 #include "oops/methodData.hpp"
58 #include "oops/objArrayKlass.inline.hpp"
59 #include "oops/oop.inline.hpp"
60 #include "runtime/atomic.inline.hpp"
61 #include "runtime/fprofiler.hpp"
62 #include "runtime/safepoint.hpp"
63 #include "runtime/vmThread.hpp"
64 #include "services/management.hpp"
65 #include "services/memTracker.hpp"
66 #include "services/memoryService.hpp"
67 #include "utilities/events.hpp"
68 #include "utilities/stack.inline.hpp"
69
70 #include <math.h>
71
72 // All sizes are in HeapWords.
73 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words
74 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
75 const size_t ParallelCompactData::RegionSizeBytes =
76 RegionSize << LogHeapWordSize;
77 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
78 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
79 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
80
81 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words
82 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize;
83 const size_t ParallelCompactData::BlockSizeBytes =
84 BlockSize << LogHeapWordSize;
85 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1;
86 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1;
87 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask;
88
89 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
90 const size_t ParallelCompactData::Log2BlocksPerRegion =
91 Log2RegionSize - Log2BlockSize;
92
93 const ParallelCompactData::RegionData::region_sz_t
94 ParallelCompactData::RegionData::dc_shift = 27;
95
96 const ParallelCompactData::RegionData::region_sz_t
97 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
98
99 const ParallelCompactData::RegionData::region_sz_t
100 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
101
102 const ParallelCompactData::RegionData::region_sz_t
103 ParallelCompactData::RegionData::los_mask = ~dc_mask;
104
105 const ParallelCompactData::RegionData::region_sz_t
106 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
107
108 const ParallelCompactData::RegionData::region_sz_t
109 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
110
111 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
112
113 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
114
115 double PSParallelCompact::_dwl_mean;
116 double PSParallelCompact::_dwl_std_dev;
117 double PSParallelCompact::_dwl_first_term;
118 double PSParallelCompact::_dwl_adjustment;
119 #ifdef ASSERT
120 bool PSParallelCompact::_dwl_initialized = false;
121 #endif // #ifdef ASSERT
122
123 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
124 HeapWord* destination)
125 {
126 assert(src_region_idx != 0, "invalid src_region_idx");
127 assert(partial_obj_size != 0, "invalid partial_obj_size argument");
128 assert(destination != NULL, "invalid destination argument");
129
130 _src_region_idx = src_region_idx;
131 _partial_obj_size = partial_obj_size;
132 _destination = destination;
133
134 // These fields may not be updated below, so make sure they're clear.
135 assert(_dest_region_addr == NULL, "should have been cleared");
136 assert(_first_src_addr == NULL, "should have been cleared");
137
138 // Determine the number of destination regions for the partial object.
139 HeapWord* const last_word = destination + partial_obj_size - 1;
140 const ParallelCompactData& sd = PSParallelCompact::summary_data();
141 HeapWord* const beg_region_addr = sd.region_align_down(destination);
142 HeapWord* const end_region_addr = sd.region_align_down(last_word);
143
144 if (beg_region_addr == end_region_addr) {
145 // One destination region.
146 _destination_count = 1;
147 if (end_region_addr == destination) {
148 // The destination falls on a region boundary, thus the first word of the
149 // partial object will be the first word copied to the destination region.
150 _dest_region_addr = end_region_addr;
151 _first_src_addr = sd.region_to_addr(src_region_idx);
152 }
153 } else {
154 // Two destination regions. When copied, the partial object will cross a
155 // destination region boundary, so a word somewhere within the partial
156 // object will be the first word copied to the second destination region.
157 _destination_count = 2;
158 _dest_region_addr = end_region_addr;
159 const size_t ofs = pointer_delta(end_region_addr, destination);
160 assert(ofs < _partial_obj_size, "sanity");
161 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
162 }
163 }
164
165 void SplitInfo::clear()
166 {
167 _src_region_idx = 0;
168 _partial_obj_size = 0;
169 _destination = NULL;
170 _destination_count = 0;
171 _dest_region_addr = NULL;
172 _first_src_addr = NULL;
173 assert(!is_valid(), "sanity");
174 }
175
176 #ifdef ASSERT
177 void SplitInfo::verify_clear()
178 {
179 assert(_src_region_idx == 0, "not clear");
180 assert(_partial_obj_size == 0, "not clear");
181 assert(_destination == NULL, "not clear");
182 assert(_destination_count == 0, "not clear");
183 assert(_dest_region_addr == NULL, "not clear");
184 assert(_first_src_addr == NULL, "not clear");
185 }
186 #endif // #ifdef ASSERT
187
188
189 void PSParallelCompact::print_on_error(outputStream* st) {
190 _mark_bitmap.print_on_error(st);
191 }
192
193 #ifndef PRODUCT
194 const char* PSParallelCompact::space_names[] = {
195 "old ", "eden", "from", "to "
196 };
197
198 void PSParallelCompact::print_region_ranges() {
199 if (!log_develop_is_enabled(Trace, gc, compaction)) {
200 return;
201 }
202 Log(gc, compaction) log;
203 ResourceMark rm;
204 Universe::print_on(log.trace_stream());
205 log.trace("space bottom top end new_top");
206 log.trace("------ ---------- ---------- ---------- ----------");
207
208 for (unsigned int id = 0; id < last_space_id; ++id) {
209 const MutableSpace* space = _space_info[id].space();
210 log.trace("%u %s "
211 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
212 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
213 id, space_names[id],
214 summary_data().addr_to_region_idx(space->bottom()),
215 summary_data().addr_to_region_idx(space->top()),
216 summary_data().addr_to_region_idx(space->end()),
217 summary_data().addr_to_region_idx(_space_info[id].new_top()));
218 }
219 }
220
221 void
222 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
223 {
224 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7)
225 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5)
226
227 ParallelCompactData& sd = PSParallelCompact::summary_data();
228 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
229 log_develop_trace(gc, compaction)(
230 REGION_IDX_FORMAT " " PTR_FORMAT " "
231 REGION_IDX_FORMAT " " PTR_FORMAT " "
232 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
233 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
234 i, p2i(c->data_location()), dci, p2i(c->destination()),
235 c->partial_obj_size(), c->live_obj_size(),
236 c->data_size(), c->source_region(), c->destination_count());
237
238 #undef REGION_IDX_FORMAT
239 #undef REGION_DATA_FORMAT
240 }
241
242 void
243 print_generic_summary_data(ParallelCompactData& summary_data,
244 HeapWord* const beg_addr,
245 HeapWord* const end_addr)
246 {
247 size_t total_words = 0;
248 size_t i = summary_data.addr_to_region_idx(beg_addr);
249 const size_t last = summary_data.addr_to_region_idx(end_addr);
250 HeapWord* pdest = 0;
251
252 while (i < last) {
253 ParallelCompactData::RegionData* c = summary_data.region(i);
254 if (c->data_size() != 0 || c->destination() != pdest) {
255 print_generic_summary_region(i, c);
256 total_words += c->data_size();
257 pdest = c->destination();
258 }
259 ++i;
260 }
261
262 log_develop_trace(gc, compaction)("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
263 }
264
265 void
266 print_generic_summary_data(ParallelCompactData& summary_data,
267 SpaceInfo* space_info)
268 {
269 if (!log_develop_is_enabled(Trace, gc, compaction)) {
270 return;
271 }
272
273 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
274 const MutableSpace* space = space_info[id].space();
275 print_generic_summary_data(summary_data, space->bottom(),
276 MAX2(space->top(), space_info[id].new_top()));
277 }
278 }
279
280 void
281 print_initial_summary_data(ParallelCompactData& summary_data,
282 const MutableSpace* space) {
283 if (space->top() == space->bottom()) {
284 return;
285 }
286
287 const size_t region_size = ParallelCompactData::RegionSize;
288 typedef ParallelCompactData::RegionData RegionData;
289 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
290 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
291 const RegionData* c = summary_data.region(end_region - 1);
292 HeapWord* end_addr = c->destination() + c->data_size();
293 const size_t live_in_space = pointer_delta(end_addr, space->bottom());
294
295 // Print (and count) the full regions at the beginning of the space.
296 size_t full_region_count = 0;
297 size_t i = summary_data.addr_to_region_idx(space->bottom());
298 while (i < end_region && summary_data.region(i)->data_size() == region_size) {
299 ParallelCompactData::RegionData* c = summary_data.region(i);
300 log_develop_trace(gc, compaction)(
301 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
302 i, p2i(c->destination()),
303 c->partial_obj_size(), c->live_obj_size(),
304 c->data_size(), c->source_region(), c->destination_count());
305 ++full_region_count;
306 ++i;
307 }
308
309 size_t live_to_right = live_in_space - full_region_count * region_size;
310
311 double max_reclaimed_ratio = 0.0;
312 size_t max_reclaimed_ratio_region = 0;
313 size_t max_dead_to_right = 0;
314 size_t max_live_to_right = 0;
315
316 // Print the 'reclaimed ratio' for regions while there is something live in
317 // the region or to the right of it. The remaining regions are empty (and
318 // uninteresting), and computing the ratio will result in division by 0.
319 while (i < end_region && live_to_right > 0) {
320 c = summary_data.region(i);
321 HeapWord* const region_addr = summary_data.region_to_addr(i);
322 const size_t used_to_right = pointer_delta(space->top(), region_addr);
323 const size_t dead_to_right = used_to_right - live_to_right;
324 const double reclaimed_ratio = double(dead_to_right) / live_to_right;
325
326 if (reclaimed_ratio > max_reclaimed_ratio) {
327 max_reclaimed_ratio = reclaimed_ratio;
328 max_reclaimed_ratio_region = i;
329 max_dead_to_right = dead_to_right;
330 max_live_to_right = live_to_right;
331 }
332
333 ParallelCompactData::RegionData* c = summary_data.region(i);
334 log_develop_trace(gc, compaction)(
335 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d"
336 "%12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
337 i, p2i(c->destination()),
338 c->partial_obj_size(), c->live_obj_size(),
339 c->data_size(), c->source_region(), c->destination_count(),
340 reclaimed_ratio, dead_to_right, live_to_right);
341
342
343 live_to_right -= c->data_size();
344 ++i;
345 }
346
347 // Any remaining regions are empty. Print one more if there is one.
348 if (i < end_region) {
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 i, p2i(c->destination()),
353 c->partial_obj_size(), c->live_obj_size(),
354 c->data_size(), c->source_region(), c->destination_count());
355 }
356
357 log_develop_trace(gc, compaction)("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
358 max_reclaimed_ratio_region, max_dead_to_right, max_live_to_right, max_reclaimed_ratio);
359 }
360
361 void
362 print_initial_summary_data(ParallelCompactData& summary_data,
363 SpaceInfo* space_info) {
364 if (!log_develop_is_enabled(Trace, gc, compaction)) {
365 return;
366 }
367
368 unsigned int id = PSParallelCompact::old_space_id;
369 const MutableSpace* space;
370 do {
371 space = space_info[id].space();
372 print_initial_summary_data(summary_data, space);
373 } while (++id < PSParallelCompact::eden_space_id);
374
375 do {
376 space = space_info[id].space();
377 print_generic_summary_data(summary_data, space->bottom(), space->top());
378 } while (++id < PSParallelCompact::last_space_id);
379 }
380
381 void ParallelCompact_test() {
382 if (!UseParallelGC) {
383 return;
384 }
385 // Check that print_generic_summary_data() does not print the
386 // end region by placing a bad value in the destination of the
387 // end region. The end region should not be printed because it
388 // corresponds to the space after the end of the heap.
389 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
390 ParCompactionManager* const vmthread_cm =
391 ParCompactionManager::manager_array(ParallelGCThreads);
392 HeapWord* begin_heap =
393 (HeapWord*) heap->old_gen()->virtual_space()->low_boundary();
394 HeapWord* end_heap =
395 (HeapWord*) heap->young_gen()->virtual_space()->high_boundary();
396
397 size_t end_index =
398 PSParallelCompact::summary_data().addr_to_region_idx(end_heap);
399 ParallelCompactData::RegionData* c = PSParallelCompact::summary_data().region(end_index);
400
401 // Initialize the end region with a bad destination.
402 c->set_destination(begin_heap - 1);
403
404 print_generic_summary_data(PSParallelCompact::summary_data(),
405 begin_heap, end_heap);
406 }
407 #endif // #ifndef PRODUCT
408
409 #ifdef ASSERT
410 size_t add_obj_count;
411 size_t add_obj_size;
412 size_t mark_bitmap_count;
413 size_t mark_bitmap_size;
414 #endif // #ifdef ASSERT
415
416 ParallelCompactData::ParallelCompactData()
417 {
418 _region_start = 0;
419
420 _region_vspace = 0;
421 _reserved_byte_size = 0;
422 _region_data = 0;
423 _region_count = 0;
424
425 _block_vspace = 0;
426 _block_data = 0;
427 _block_count = 0;
428 }
429
430 bool ParallelCompactData::initialize(MemRegion covered_region)
431 {
432 _region_start = covered_region.start();
433 const size_t region_size = covered_region.word_size();
434 DEBUG_ONLY(_region_end = _region_start + region_size;)
435
436 assert(region_align_down(_region_start) == _region_start,
437 "region start not aligned");
438 assert((region_size & RegionSizeOffsetMask) == 0,
439 "region size not a multiple of RegionSize");
440
441 bool result = initialize_region_data(region_size) && initialize_block_data();
442 return result;
443 }
444
445 PSVirtualSpace*
446 ParallelCompactData::create_vspace(size_t count, size_t element_size)
447 {
448 const size_t raw_bytes = count * element_size;
449 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
450 const size_t granularity = os::vm_allocation_granularity();
451 _reserved_byte_size = align_size_up(raw_bytes, MAX2(page_sz, granularity));
452
453 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
454 MAX2(page_sz, granularity);
455 ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0);
456 os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, page_sz, rs.base(),
457 rs.size());
458
459 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
460
461 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
462 if (vspace != 0) {
463 if (vspace->expand_by(_reserved_byte_size)) {
464 return vspace;
465 }
466 delete vspace;
467 // Release memory reserved in the space.
468 rs.release();
469 }
470
471 return 0;
472 }
473
474 bool ParallelCompactData::initialize_region_data(size_t region_size)
475 {
476 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
477 _region_vspace = create_vspace(count, sizeof(RegionData));
478 if (_region_vspace != 0) {
479 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
480 _region_count = count;
481 return true;
482 }
483 return false;
484 }
485
486 bool ParallelCompactData::initialize_block_data()
487 {
488 assert(_region_count != 0, "region data must be initialized first");
489 const size_t count = _region_count << Log2BlocksPerRegion;
490 _block_vspace = create_vspace(count, sizeof(BlockData));
491 if (_block_vspace != 0) {
492 _block_data = (BlockData*)_block_vspace->reserved_low_addr();
493 _block_count = count;
494 return true;
495 }
496 return false;
497 }
498
499 void ParallelCompactData::clear()
500 {
501 memset(_region_data, 0, _region_vspace->committed_size());
502 memset(_block_data, 0, _block_vspace->committed_size());
503 }
504
505 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
506 assert(beg_region <= _region_count, "beg_region out of range");
507 assert(end_region <= _region_count, "end_region out of range");
508 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize");
509
510 const size_t region_cnt = end_region - beg_region;
511 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
512
513 const size_t beg_block = beg_region * BlocksPerRegion;
514 const size_t block_cnt = region_cnt * BlocksPerRegion;
515 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));
516 }
517
518 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
519 {
520 const RegionData* cur_cp = region(region_idx);
521 const RegionData* const end_cp = region(region_count() - 1);
522
523 HeapWord* result = region_to_addr(region_idx);
524 if (cur_cp < end_cp) {
525 do {
526 result += cur_cp->partial_obj_size();
527 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
528 }
529 return result;
530 }
531
532 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
533 {
534 const size_t obj_ofs = pointer_delta(addr, _region_start);
535 const size_t beg_region = obj_ofs >> Log2RegionSize;
536 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
537
538 DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
539 DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
540
541 if (beg_region == end_region) {
542 // All in one region.
543 _region_data[beg_region].add_live_obj(len);
544 return;
545 }
546
547 // First region.
548 const size_t beg_ofs = region_offset(addr);
549 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
550
551 Klass* klass = ((oop)addr)->klass();
552 // Middle regions--completely spanned by this object.
553 for (size_t region = beg_region + 1; region < end_region; ++region) {
554 _region_data[region].set_partial_obj_size(RegionSize);
555 _region_data[region].set_partial_obj_addr(addr);
556 }
557
558 // Last region.
559 const size_t end_ofs = region_offset(addr + len - 1);
560 _region_data[end_region].set_partial_obj_size(end_ofs + 1);
561 _region_data[end_region].set_partial_obj_addr(addr);
562 }
563
564 void
565 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
566 {
567 assert(region_offset(beg) == 0, "not RegionSize aligned");
568 assert(region_offset(end) == 0, "not RegionSize aligned");
569
570 size_t cur_region = addr_to_region_idx(beg);
571 const size_t end_region = addr_to_region_idx(end);
572 HeapWord* addr = beg;
573 while (cur_region < end_region) {
574 _region_data[cur_region].set_destination(addr);
575 _region_data[cur_region].set_destination_count(0);
576 _region_data[cur_region].set_source_region(cur_region);
577 _region_data[cur_region].set_data_location(addr);
578
579 // Update live_obj_size so the region appears completely full.
580 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
581 _region_data[cur_region].set_live_obj_size(live_size);
582
583 ++cur_region;
584 addr += RegionSize;
585 }
586 }
587
588 // Find the point at which a space can be split and, if necessary, record the
589 // split point.
590 //
591 // If the current src region (which overflowed the destination space) doesn't
592 // have a partial object, the split point is at the beginning of the current src
593 // region (an "easy" split, no extra bookkeeping required).
594 //
595 // If the current src region has a partial object, the split point is in the
596 // region where that partial object starts (call it the split_region). If
597 // split_region has a partial object, then the split point is just after that
598 // partial object (a "hard" split where we have to record the split data and
599 // zero the partial_obj_size field). With a "hard" split, we know that the
600 // partial_obj ends within split_region because the partial object that caused
601 // the overflow starts in split_region. If split_region doesn't have a partial
602 // obj, then the split is at the beginning of split_region (another "easy"
603 // split).
604 HeapWord*
605 ParallelCompactData::summarize_split_space(size_t src_region,
606 SplitInfo& split_info,
607 HeapWord* destination,
608 HeapWord* target_end,
609 HeapWord** target_next)
610 {
611 assert(destination <= target_end, "sanity");
612 assert(destination + _region_data[src_region].data_size() > target_end,
613 "region should not fit into target space");
614 assert(is_region_aligned(target_end), "sanity");
615
616 size_t split_region = src_region;
617 HeapWord* split_destination = destination;
618 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
619
620 if (destination + partial_obj_size > target_end) {
621 // The split point is just after the partial object (if any) in the
622 // src_region that contains the start of the object that overflowed the
623 // destination space.
624 //
625 // Find the start of the "overflow" object and set split_region to the
626 // region containing it.
627 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
628 split_region = addr_to_region_idx(overflow_obj);
629
630 // Clear the source_region field of all destination regions whose first word
631 // came from data after the split point (a non-null source_region field
632 // implies a region must be filled).
633 //
634 // An alternative to the simple loop below: clear during post_compact(),
635 // which uses memcpy instead of individual stores, and is easy to
636 // parallelize. (The downside is that it clears the entire RegionData
637 // object as opposed to just one field.)
638 //
639 // post_compact() would have to clear the summary data up to the highest
640 // address that was written during the summary phase, which would be
641 //
642 // max(top, max(new_top, clear_top))
643 //
644 // where clear_top is a new field in SpaceInfo. Would have to set clear_top
645 // to target_end.
646 const RegionData* const sr = region(split_region);
647 const size_t beg_idx =
648 addr_to_region_idx(region_align_up(sr->destination() +
649 sr->partial_obj_size()));
650 const size_t end_idx = addr_to_region_idx(target_end);
651
652 log_develop_trace(gc, compaction)("split: clearing source_region field in [" SIZE_FORMAT ", " SIZE_FORMAT ")", beg_idx, end_idx);
653 for (size_t idx = beg_idx; idx < end_idx; ++idx) {
654 _region_data[idx].set_source_region(0);
655 }
656
657 // Set split_destination and partial_obj_size to reflect the split region.
658 split_destination = sr->destination();
659 partial_obj_size = sr->partial_obj_size();
660 }
661
662 // The split is recorded only if a partial object extends onto the region.
663 if (partial_obj_size != 0) {
664 _region_data[split_region].set_partial_obj_size(0);
665 split_info.record(split_region, partial_obj_size, split_destination);
666 }
667
668 // Setup the continuation addresses.
669 *target_next = split_destination + partial_obj_size;
670 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
671
672 if (log_develop_is_enabled(Trace, gc, compaction)) {
673 const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
674 log_develop_trace(gc, compaction)("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT " pos=" SIZE_FORMAT,
675 split_type, p2i(source_next), split_region, partial_obj_size);
676 log_develop_trace(gc, compaction)("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT " tn=" PTR_FORMAT,
677 split_type, p2i(split_destination),
678 addr_to_region_idx(split_destination),
679 p2i(*target_next));
680
681 if (partial_obj_size != 0) {
682 HeapWord* const po_beg = split_info.destination();
683 HeapWord* const po_end = po_beg + split_info.partial_obj_size();
684 log_develop_trace(gc, compaction)("%s split: po_beg=" PTR_FORMAT " " SIZE_FORMAT " po_end=" PTR_FORMAT " " SIZE_FORMAT,
685 split_type,
686 p2i(po_beg), addr_to_region_idx(po_beg),
687 p2i(po_end), addr_to_region_idx(po_end));
688 }
689 }
690
691 return source_next;
692 }
693
694 bool ParallelCompactData::summarize(SplitInfo& split_info,
695 HeapWord* source_beg, HeapWord* source_end,
696 HeapWord** source_next,
697 HeapWord* target_beg, HeapWord* target_end,
698 HeapWord** target_next)
699 {
700 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
701 log_develop_trace(gc, compaction)(
702 "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
703 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
704 p2i(source_beg), p2i(source_end), p2i(source_next_val),
705 p2i(target_beg), p2i(target_end), p2i(*target_next));
706
707 size_t cur_region = addr_to_region_idx(source_beg);
708 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
709
710 HeapWord *dest_addr = target_beg;
711 while (cur_region < end_region) {
712 // The destination must be set even if the region has no data.
713 _region_data[cur_region].set_destination(dest_addr);
714
715 size_t words = _region_data[cur_region].data_size();
716 if (words > 0) {
717 // If cur_region does not fit entirely into the target space, find a point
718 // at which the source space can be 'split' so that part is copied to the
719 // target space and the rest is copied elsewhere.
720 if (dest_addr + words > target_end) {
721 assert(source_next != NULL, "source_next is NULL when splitting");
722 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
723 target_end, target_next);
724 return false;
725 }
726
727 // Compute the destination_count for cur_region, and if necessary, update
728 // source_region for a destination region. The source_region field is
729 // updated if cur_region is the first (left-most) region to be copied to a
730 // destination region.
731 //
732 // The destination_count calculation is a bit subtle. A region that has
733 // data that compacts into itself does not count itself as a destination.
734 // This maintains the invariant that a zero count means the region is
735 // available and can be claimed and then filled.
736 uint destination_count = 0;
737 if (split_info.is_split(cur_region)) {
738 // The current region has been split: the partial object will be copied
739 // to one destination space and the remaining data will be copied to
740 // another destination space. Adjust the initial destination_count and,
741 // if necessary, set the source_region field if the partial object will
742 // cross a destination region boundary.
743 destination_count = split_info.destination_count();
744 if (destination_count == 2) {
745 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
746 _region_data[dest_idx].set_source_region(cur_region);
747 }
748 }
749
750 HeapWord* const last_addr = dest_addr + words - 1;
751 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
752 const size_t dest_region_2 = addr_to_region_idx(last_addr);
753
754 // Initially assume that the destination regions will be the same and
755 // adjust the value below if necessary. Under this assumption, if
756 // cur_region == dest_region_2, then cur_region will be compacted
757 // completely into itself.
758 destination_count += cur_region == dest_region_2 ? 0 : 1;
759 if (dest_region_1 != dest_region_2) {
760 // Destination regions differ; adjust destination_count.
761 destination_count += 1;
762 // Data from cur_region will be copied to the start of dest_region_2.
763 _region_data[dest_region_2].set_source_region(cur_region);
764 } else if (region_offset(dest_addr) == 0) {
765 // Data from cur_region will be copied to the start of the destination
766 // region.
767 _region_data[dest_region_1].set_source_region(cur_region);
768 }
769
770 _region_data[cur_region].set_destination_count(destination_count);
771 _region_data[cur_region].set_data_location(region_to_addr(cur_region));
772 dest_addr += words;
773 }
774
775 ++cur_region;
776 }
777
778 *target_next = dest_addr;
779 return true;
780 }
781
782 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr, ParCompactionManager* cm) {
783 assert(addr != NULL, "Should detect NULL oop earlier");
784 assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap");
785 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked");
786
787 // Region covering the object.
788 RegionData* const region_ptr = addr_to_region_ptr(addr);
789 HeapWord* result = region_ptr->destination();
790
791 // If the entire Region is live, the new location is region->destination + the
792 // offset of the object within in the Region.
793
794 // Run some performance tests to determine if this special case pays off. It
795 // is worth it for pointers into the dense prefix. If the optimization to
796 // avoid pointer updates in regions that only point to the dense prefix is
797 // ever implemented, this should be revisited.
798 if (region_ptr->data_size() == RegionSize) {
799 result += region_offset(addr);
800 return result;
801 }
802
803 // Otherwise, the new location is region->destination + block offset + the
804 // number of live words in the Block that are (a) to the left of addr and (b)
805 // due to objects that start in the Block.
806
807 // Fill in the block table if necessary. This is unsynchronized, so multiple
808 // threads may fill the block table for a region (harmless, since it is
809 // idempotent).
810 if (!region_ptr->blocks_filled()) {
811 PSParallelCompact::fill_blocks(addr_to_region_idx(addr));
812 region_ptr->set_blocks_filled();
813 }
814
815 HeapWord* const search_start = block_align_down(addr);
816 const size_t block_offset = addr_to_block_ptr(addr)->offset();
817
818 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
819 const size_t live = bitmap->live_words_in_range(cm, search_start, oop(addr));
820 result += block_offset + live;
821 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result));
822 return result;
823 }
824
825 #ifdef ASSERT
826 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
827 {
828 const size_t* const beg = (const size_t*)vspace->committed_low_addr();
829 const size_t* const end = (const size_t*)vspace->committed_high_addr();
830 for (const size_t* p = beg; p < end; ++p) {
831 assert(*p == 0, "not zero");
832 }
833 }
834
835 void ParallelCompactData::verify_clear()
836 {
837 verify_clear(_region_vspace);
838 verify_clear(_block_vspace);
839 }
840 #endif // #ifdef ASSERT
841
842 STWGCTimer PSParallelCompact::_gc_timer;
843 ParallelOldTracer PSParallelCompact::_gc_tracer;
844 elapsedTimer PSParallelCompact::_accumulated_time;
845 unsigned int PSParallelCompact::_total_invocations = 0;
846 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
847 jlong PSParallelCompact::_time_of_last_gc = 0;
848 CollectorCounters* PSParallelCompact::_counters = NULL;
849 ParMarkBitMap PSParallelCompact::_mark_bitmap;
850 ParallelCompactData PSParallelCompact::_summary_data;
851
852 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
853
854 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
855
856 void PSParallelCompact::AdjustKlassClosure::do_klass(Klass* klass) {
857 PSParallelCompact::AdjustPointerClosure closure(_cm);
858 klass->oops_do(&closure);
859 }
860
861 void PSParallelCompact::post_initialize() {
862 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
863 MemRegion mr = heap->reserved_region();
864 _ref_processor =
865 new ReferenceProcessor(mr, // span
866 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
867 ParallelGCThreads, // mt processing degree
868 true, // mt discovery
869 ParallelGCThreads, // mt discovery degree
870 true, // atomic_discovery
871 &_is_alive_closure); // non-header is alive closure
872 _counters = new CollectorCounters("PSParallelCompact", 1);
873
874 // Dummy counter
875 new CollectorCounters("dummy", 2);
876
877 // Initialize static fields in ParCompactionManager.
878 ParCompactionManager::initialize(mark_bitmap());
879 }
880
881 bool PSParallelCompact::initialize() {
882 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
883 MemRegion mr = heap->reserved_region();
884
885 // Was the old gen get allocated successfully?
886 if (!heap->old_gen()->is_allocated()) {
887 return false;
888 }
889
890 initialize_space_info();
891 initialize_dead_wood_limiter();
892
893 if (!_mark_bitmap.initialize(mr)) {
894 vm_shutdown_during_initialization(
895 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
896 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
897 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
898 return false;
899 }
900
901 if (!_summary_data.initialize(mr)) {
902 vm_shutdown_during_initialization(
903 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
904 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
905 _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
906 return false;
907 }
908
909 return true;
910 }
911
912 void PSParallelCompact::initialize_space_info()
913 {
914 memset(&_space_info, 0, sizeof(_space_info));
915
916 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
917 PSYoungGen* young_gen = heap->young_gen();
918
919 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
920 _space_info[eden_space_id].set_space(young_gen->eden_space());
921 _space_info[from_space_id].set_space(young_gen->from_space());
922 _space_info[to_space_id].set_space(young_gen->to_space());
923
924 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
925 }
926
927 void PSParallelCompact::initialize_dead_wood_limiter()
928 {
929 const size_t max = 100;
930 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
931 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
932 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
933 DEBUG_ONLY(_dwl_initialized = true;)
934 _dwl_adjustment = normal_distribution(1.0);
935 }
936
937 void
938 PSParallelCompact::clear_data_covering_space(SpaceId id)
939 {
940 // At this point, top is the value before GC, new_top() is the value that will
941 // be set at the end of GC. The marking bitmap is cleared to top; nothing
942 // should be marked above top. The summary data is cleared to the larger of
943 // top & new_top.
944 MutableSpace* const space = _space_info[id].space();
945 HeapWord* const bot = space->bottom();
946 HeapWord* const top = space->top();
947 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
948
949 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
950 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
951 _mark_bitmap.clear_range(beg_bit, end_bit);
952
953 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
954 const size_t end_region =
955 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
956 _summary_data.clear_range(beg_region, end_region);
957
958 // Clear the data used to 'split' regions.
959 SplitInfo& split_info = _space_info[id].split_info();
960 if (split_info.is_valid()) {
961 split_info.clear();
962 }
963 DEBUG_ONLY(split_info.verify_clear();)
964 }
965
966 void PSParallelCompact::pre_compact()
967 {
968 // Update the from & to space pointers in space_info, since they are swapped
969 // at each young gen gc. Do the update unconditionally (even though a
970 // promotion failure does not swap spaces) because an unknown number of young
971 // collections will have swapped the spaces an unknown number of times.
972 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer);
973 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
974 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
975 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
976
977 DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
978 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
979
980 // Increment the invocation count
981 heap->increment_total_collections(true);
982
983 // We need to track unique mark sweep invocations as well.
984 _total_invocations++;
985
986 heap->print_heap_before_gc();
987 heap->trace_heap_before_gc(&_gc_tracer);
988
989 // Fill in TLABs
990 heap->accumulate_statistics_all_tlabs();
991 heap->ensure_parsability(true); // retire TLABs
992
993 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
994 HandleMark hm; // Discard invalid handles created during verification
995 Universe::verify("Before GC");
996 }
997
998 // Verify object start arrays
999 if (VerifyObjectStartArray &&
1000 VerifyBeforeGC) {
1001 heap->old_gen()->verify_object_start_array();
1002 }
1003
1004 DEBUG_ONLY(mark_bitmap()->verify_clear();)
1005 DEBUG_ONLY(summary_data().verify_clear();)
1006
1007 // Have worker threads release resources the next time they run a task.
1008 gc_task_manager()->release_all_resources();
1009
1010 ParCompactionManager::reset_all_bitmap_query_caches();
1011 }
1012
1013 void PSParallelCompact::post_compact()
1014 {
1015 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer);
1016
1017 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1018 // Clear the marking bitmap, summary data and split info.
1019 clear_data_covering_space(SpaceId(id));
1020 // Update top(). Must be done after clearing the bitmap and summary data.
1021 _space_info[id].publish_new_top();
1022 }
1023
1024 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1025 MutableSpace* const from_space = _space_info[from_space_id].space();
1026 MutableSpace* const to_space = _space_info[to_space_id].space();
1027
1028 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1029 bool eden_empty = eden_space->is_empty();
1030 if (!eden_empty) {
1031 eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1032 heap->young_gen(), heap->old_gen());
1033 }
1034
1035 // Update heap occupancy information which is used as input to the soft ref
1036 // clearing policy at the next gc.
1037 Universe::update_heap_info_at_gc();
1038
1039 bool young_gen_empty = eden_empty && from_space->is_empty() &&
1040 to_space->is_empty();
1041
1042 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set());
1043 MemRegion old_mr = heap->old_gen()->reserved();
1044 if (young_gen_empty) {
1045 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
1046 } else {
1047 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1048 }
1049
1050 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1051 ClassLoaderDataGraph::purge();
1052 MetaspaceAux::verify_metrics();
1053
1054 CodeCache::gc_epilogue();
1055 JvmtiExport::gc_epilogue();
1056
1057 #if defined(COMPILER2) || INCLUDE_JVMCI
1058 DerivedPointerTable::update_pointers();
1059 #endif
1060
1061 ref_processor()->enqueue_discovered_references(NULL);
1062
1063 if (ZapUnusedHeapArea) {
1064 heap->gen_mangle_unused_area();
1065 }
1066
1067 // Update time of last GC
1068 reset_millis_since_last_gc();
1069 }
1070
1071 HeapWord*
1072 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1073 bool maximum_compaction)
1074 {
1075 const size_t region_size = ParallelCompactData::RegionSize;
1076 const ParallelCompactData& sd = summary_data();
1077
1078 const MutableSpace* const space = _space_info[id].space();
1079 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1080 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1081 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1082
1083 // Skip full regions at the beginning of the space--they are necessarily part
1084 // of the dense prefix.
1085 size_t full_count = 0;
1086 const RegionData* cp;
1087 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1088 ++full_count;
1089 }
1090
1091 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1092 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1093 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1094 if (maximum_compaction || cp == end_cp || interval_ended) {
1095 _maximum_compaction_gc_num = total_invocations();
1096 return sd.region_to_addr(cp);
1097 }
1098
1099 HeapWord* const new_top = _space_info[id].new_top();
1100 const size_t space_live = pointer_delta(new_top, space->bottom());
1101 const size_t space_used = space->used_in_words();
1102 const size_t space_capacity = space->capacity_in_words();
1103
1104 const double cur_density = double(space_live) / space_capacity;
1105 const double deadwood_density =
1106 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1107 const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1108
1109 if (TraceParallelOldGCDensePrefix) {
1110 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1111 cur_density, deadwood_density, deadwood_goal);
1112 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1113 "space_cap=" SIZE_FORMAT,
1114 space_live, space_used,
1115 space_capacity);
1116 }
1117
1118 // XXX - Use binary search?
1119 HeapWord* dense_prefix = sd.region_to_addr(cp);
1120 const RegionData* full_cp = cp;
1121 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1122 while (cp < end_cp) {
1123 HeapWord* region_destination = cp->destination();
1124 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1125 if (TraceParallelOldGCDensePrefix && Verbose) {
1126 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1127 "dp=" PTR_FORMAT " " "cdw=" SIZE_FORMAT_W(8),
1128 sd.region(cp), p2i(region_destination),
1129 p2i(dense_prefix), cur_deadwood);
1130 }
1131
1132 if (cur_deadwood >= deadwood_goal) {
1133 // Found the region that has the correct amount of deadwood to the left.
1134 // This typically occurs after crossing a fairly sparse set of regions, so
1135 // iterate backwards over those sparse regions, looking for the region
1136 // that has the lowest density of live objects 'to the right.'
1137 size_t space_to_left = sd.region(cp) * region_size;
1138 size_t live_to_left = space_to_left - cur_deadwood;
1139 size_t space_to_right = space_capacity - space_to_left;
1140 size_t live_to_right = space_live - live_to_left;
1141 double density_to_right = double(live_to_right) / space_to_right;
1142 while (cp > full_cp) {
1143 --cp;
1144 const size_t prev_region_live_to_right = live_to_right -
1145 cp->data_size();
1146 const size_t prev_region_space_to_right = space_to_right + region_size;
1147 double prev_region_density_to_right =
1148 double(prev_region_live_to_right) / prev_region_space_to_right;
1149 if (density_to_right <= prev_region_density_to_right) {
1150 return dense_prefix;
1151 }
1152 if (TraceParallelOldGCDensePrefix && Verbose) {
1153 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1154 "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1155 prev_region_density_to_right);
1156 }
1157 dense_prefix -= region_size;
1158 live_to_right = prev_region_live_to_right;
1159 space_to_right = prev_region_space_to_right;
1160 density_to_right = prev_region_density_to_right;
1161 }
1162 return dense_prefix;
1163 }
1164
1165 dense_prefix += region_size;
1166 ++cp;
1167 }
1168
1169 return dense_prefix;
1170 }
1171
1172 #ifndef PRODUCT
1173 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1174 const SpaceId id,
1175 const bool maximum_compaction,
1176 HeapWord* const addr)
1177 {
1178 const size_t region_idx = summary_data().addr_to_region_idx(addr);
1179 RegionData* const cp = summary_data().region(region_idx);
1180 const MutableSpace* const space = _space_info[id].space();
1181 HeapWord* const new_top = _space_info[id].new_top();
1182
1183 const size_t space_live = pointer_delta(new_top, space->bottom());
1184 const size_t dead_to_left = pointer_delta(addr, cp->destination());
1185 const size_t space_cap = space->capacity_in_words();
1186 const double dead_to_left_pct = double(dead_to_left) / space_cap;
1187 const size_t live_to_right = new_top - cp->destination();
1188 const size_t dead_to_right = space->top() - addr - live_to_right;
1189
1190 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1191 "spl=" SIZE_FORMAT " "
1192 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1193 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1194 " ratio=%10.8f",
1195 algorithm, p2i(addr), region_idx,
1196 space_live,
1197 dead_to_left, dead_to_left_pct,
1198 dead_to_right, live_to_right,
1199 double(dead_to_right) / live_to_right);
1200 }
1201 #endif // #ifndef PRODUCT
1202
1203 // Return a fraction indicating how much of the generation can be treated as
1204 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution
1205 // based on the density of live objects in the generation to determine a limit,
1206 // which is then adjusted so the return value is min_percent when the density is
1207 // 1.
1208 //
1209 // The following table shows some return values for a different values of the
1210 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1211 // min_percent is 1.
1212 //
1213 // fraction allowed as dead wood
1214 // -----------------------------------------------------------------
1215 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1216 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1217 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1218 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1219 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1220 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1221 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1222 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1223 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1224 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1225 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1226 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1227 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1228 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1229 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1230 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1231 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1232 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1233 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1234 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1235 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1236 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1237 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1238
1239 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1240 {
1241 assert(_dwl_initialized, "uninitialized");
1242
1243 // The raw limit is the value of the normal distribution at x = density.
1244 const double raw_limit = normal_distribution(density);
1245
1246 // Adjust the raw limit so it becomes the minimum when the density is 1.
1247 //
1248 // First subtract the adjustment value (which is simply the precomputed value
1249 // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1250 // Then add the minimum value, so the minimum is returned when the density is
1251 // 1. Finally, prevent negative values, which occur when the mean is not 0.5.
1252 const double min = double(min_percent) / 100.0;
1253 const double limit = raw_limit - _dwl_adjustment + min;
1254 return MAX2(limit, 0.0);
1255 }
1256
1257 ParallelCompactData::RegionData*
1258 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1259 const RegionData* end)
1260 {
1261 const size_t region_size = ParallelCompactData::RegionSize;
1262 ParallelCompactData& sd = summary_data();
1263 size_t left = sd.region(beg);
1264 size_t right = end > beg ? sd.region(end) - 1 : left;
1265
1266 // Binary search.
1267 while (left < right) {
1268 // Equivalent to (left + right) / 2, but does not overflow.
1269 const size_t middle = left + (right - left) / 2;
1270 RegionData* const middle_ptr = sd.region(middle);
1271 HeapWord* const dest = middle_ptr->destination();
1272 HeapWord* const addr = sd.region_to_addr(middle);
1273 assert(dest != NULL, "sanity");
1274 assert(dest <= addr, "must move left");
1275
1276 if (middle > left && dest < addr) {
1277 right = middle - 1;
1278 } else if (middle < right && middle_ptr->data_size() == region_size) {
1279 left = middle + 1;
1280 } else {
1281 return middle_ptr;
1282 }
1283 }
1284 return sd.region(left);
1285 }
1286
1287 ParallelCompactData::RegionData*
1288 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1289 const RegionData* end,
1290 size_t dead_words)
1291 {
1292 ParallelCompactData& sd = summary_data();
1293 size_t left = sd.region(beg);
1294 size_t right = end > beg ? sd.region(end) - 1 : left;
1295
1296 // Binary search.
1297 while (left < right) {
1298 // Equivalent to (left + right) / 2, but does not overflow.
1299 const size_t middle = left + (right - left) / 2;
1300 RegionData* const middle_ptr = sd.region(middle);
1301 HeapWord* const dest = middle_ptr->destination();
1302 HeapWord* const addr = sd.region_to_addr(middle);
1303 assert(dest != NULL, "sanity");
1304 assert(dest <= addr, "must move left");
1305
1306 const size_t dead_to_left = pointer_delta(addr, dest);
1307 if (middle > left && dead_to_left > dead_words) {
1308 right = middle - 1;
1309 } else if (middle < right && dead_to_left < dead_words) {
1310 left = middle + 1;
1311 } else {
1312 return middle_ptr;
1313 }
1314 }
1315 return sd.region(left);
1316 }
1317
1318 // The result is valid during the summary phase, after the initial summarization
1319 // of each space into itself, and before final summarization.
1320 inline double
1321 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1322 HeapWord* const bottom,
1323 HeapWord* const top,
1324 HeapWord* const new_top)
1325 {
1326 ParallelCompactData& sd = summary_data();
1327
1328 assert(cp != NULL, "sanity");
1329 assert(bottom != NULL, "sanity");
1330 assert(top != NULL, "sanity");
1331 assert(new_top != NULL, "sanity");
1332 assert(top >= new_top, "summary data problem?");
1333 assert(new_top > bottom, "space is empty; should not be here");
1334 assert(new_top >= cp->destination(), "sanity");
1335 assert(top >= sd.region_to_addr(cp), "sanity");
1336
1337 HeapWord* const destination = cp->destination();
1338 const size_t dense_prefix_live = pointer_delta(destination, bottom);
1339 const size_t compacted_region_live = pointer_delta(new_top, destination);
1340 const size_t compacted_region_used = pointer_delta(top,
1341 sd.region_to_addr(cp));
1342 const size_t reclaimable = compacted_region_used - compacted_region_live;
1343
1344 const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1345 return double(reclaimable) / divisor;
1346 }
1347
1348 // Return the address of the end of the dense prefix, a.k.a. the start of the
1349 // compacted region. The address is always on a region boundary.
1350 //
1351 // Completely full regions at the left are skipped, since no compaction can
1352 // occur in those regions. Then the maximum amount of dead wood to allow is
1353 // computed, based on the density (amount live / capacity) of the generation;
1354 // the region with approximately that amount of dead space to the left is
1355 // identified as the limit region. Regions between the last completely full
1356 // region and the limit region are scanned and the one that has the best
1357 // (maximum) reclaimed_ratio() is selected.
1358 HeapWord*
1359 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1360 bool maximum_compaction)
1361 {
1362 const size_t region_size = ParallelCompactData::RegionSize;
1363 const ParallelCompactData& sd = summary_data();
1364
1365 const MutableSpace* const space = _space_info[id].space();
1366 HeapWord* const top = space->top();
1367 HeapWord* const top_aligned_up = sd.region_align_up(top);
1368 HeapWord* const new_top = _space_info[id].new_top();
1369 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1370 HeapWord* const bottom = space->bottom();
1371 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1372 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1373 const RegionData* const new_top_cp =
1374 sd.addr_to_region_ptr(new_top_aligned_up);
1375
1376 // Skip full regions at the beginning of the space--they are necessarily part
1377 // of the dense prefix.
1378 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1379 assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1380 space->is_empty(), "no dead space allowed to the left");
1381 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1382 "region must have dead space");
1383
1384 // The gc number is saved whenever a maximum compaction is done, and used to
1385 // determine when the maximum compaction interval has expired. This avoids
1386 // successive max compactions for different reasons.
1387 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1388 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1389 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1390 total_invocations() == HeapFirstMaximumCompactionCount;
1391 if (maximum_compaction || full_cp == top_cp || interval_ended) {
1392 _maximum_compaction_gc_num = total_invocations();
1393 return sd.region_to_addr(full_cp);
1394 }
1395
1396 const size_t space_live = pointer_delta(new_top, bottom);
1397 const size_t space_used = space->used_in_words();
1398 const size_t space_capacity = space->capacity_in_words();
1399
1400 const double density = double(space_live) / double(space_capacity);
1401 const size_t min_percent_free = MarkSweepDeadRatio;
1402 const double limiter = dead_wood_limiter(density, min_percent_free);
1403 const size_t dead_wood_max = space_used - space_live;
1404 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1405 dead_wood_max);
1406
1407 if (TraceParallelOldGCDensePrefix) {
1408 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1409 "space_cap=" SIZE_FORMAT,
1410 space_live, space_used,
1411 space_capacity);
1412 tty->print_cr("dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f "
1413 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1414 density, min_percent_free, limiter,
1415 dead_wood_max, dead_wood_limit);
1416 }
1417
1418 // Locate the region with the desired amount of dead space to the left.
1419 const RegionData* const limit_cp =
1420 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1421
1422 // Scan from the first region with dead space to the limit region and find the
1423 // one with the best (largest) reclaimed ratio.
1424 double best_ratio = 0.0;
1425 const RegionData* best_cp = full_cp;
1426 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1427 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1428 if (tmp_ratio > best_ratio) {
1429 best_cp = cp;
1430 best_ratio = tmp_ratio;
1431 }
1432 }
1433
1434 return sd.region_to_addr(best_cp);
1435 }
1436
1437 void PSParallelCompact::summarize_spaces_quick()
1438 {
1439 for (unsigned int i = 0; i < last_space_id; ++i) {
1440 const MutableSpace* space = _space_info[i].space();
1441 HeapWord** nta = _space_info[i].new_top_addr();
1442 bool result = _summary_data.summarize(_space_info[i].split_info(),
1443 space->bottom(), space->top(), NULL,
1444 space->bottom(), space->end(), nta);
1445 assert(result, "space must fit into itself");
1446 _space_info[i].set_dense_prefix(space->bottom());
1447 }
1448 }
1449
1450 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1451 {
1452 HeapWord* const dense_prefix_end = dense_prefix(id);
1453 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1454 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1455 if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1456 // Only enough dead space is filled so that any remaining dead space to the
1457 // left is larger than the minimum filler object. (The remainder is filled
1458 // during the copy/update phase.)
1459 //
1460 // The size of the dead space to the right of the boundary is not a
1461 // concern, since compaction will be able to use whatever space is
1462 // available.
1463 //
1464 // Here '||' is the boundary, 'x' represents a don't care bit and a box
1465 // surrounds the space to be filled with an object.
1466 //
1467 // In the 32-bit VM, each bit represents two 32-bit words:
1468 // +---+
1469 // a) beg_bits: ... x x x | 0 | || 0 x x ...
1470 // end_bits: ... x x x | 0 | || 0 x x ...
1471 // +---+
1472 //
1473 // In the 64-bit VM, each bit represents one 64-bit word:
1474 // +------------+
1475 // b) beg_bits: ... x x x | 0 || 0 | x x ...
1476 // end_bits: ... x x 1 | 0 || 0 | x x ...
1477 // +------------+
1478 // +-------+
1479 // c) beg_bits: ... x x | 0 0 | || 0 x x ...
1480 // end_bits: ... x 1 | 0 0 | || 0 x x ...
1481 // +-------+
1482 // +-----------+
1483 // d) beg_bits: ... x | 0 0 0 | || 0 x x ...
1484 // end_bits: ... 1 | 0 0 0 | || 0 x x ...
1485 // +-----------+
1486 // +-------+
1487 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ...
1488 // end_bits: ... 0 0 | 0 0 | || 0 x x ...
1489 // +-------+
1490
1491 // Initially assume case a, c or e will apply.
1492 size_t obj_len = CollectedHeap::min_fill_size();
1493 HeapWord* obj_beg = dense_prefix_end - obj_len;
1494
1495 #ifdef _LP64
1496 if (MinObjAlignment > 1) { // object alignment > heap word size
1497 // Cases a, c or e.
1498 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1499 // Case b above.
1500 obj_beg = dense_prefix_end - 1;
1501 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1502 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1503 // Case d above.
1504 obj_beg = dense_prefix_end - 3;
1505 obj_len = 3;
1506 }
1507 #endif // #ifdef _LP64
1508
1509 CollectedHeap::fill_with_object(obj_beg, obj_len);
1510 _mark_bitmap.mark_obj(obj_beg, obj_len);
1511 _summary_data.add_obj(obj_beg, obj_len);
1512 assert(start_array(id) != NULL, "sanity");
1513 start_array(id)->allocate_block(obj_beg);
1514 }
1515 }
1516
1517 void
1518 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1519 {
1520 assert(id < last_space_id, "id out of range");
1521 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(),
1522 "should have been reset in summarize_spaces_quick()");
1523
1524 const MutableSpace* space = _space_info[id].space();
1525 if (_space_info[id].new_top() != space->bottom()) {
1526 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1527 _space_info[id].set_dense_prefix(dense_prefix_end);
1528
1529 #ifndef PRODUCT
1530 if (TraceParallelOldGCDensePrefix) {
1531 print_dense_prefix_stats("ratio", id, maximum_compaction,
1532 dense_prefix_end);
1533 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1534 print_dense_prefix_stats("density", id, maximum_compaction, addr);
1535 }
1536 #endif // #ifndef PRODUCT
1537
1538 // Recompute the summary data, taking into account the dense prefix. If
1539 // every last byte will be reclaimed, then the existing summary data which
1540 // compacts everything can be left in place.
1541 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1542 // If dead space crosses the dense prefix boundary, it is (at least
1543 // partially) filled with a dummy object, marked live and added to the
1544 // summary data. This simplifies the copy/update phase and must be done
1545 // before the final locations of objects are determined, to prevent
1546 // leaving a fragment of dead space that is too small to fill.
1547 fill_dense_prefix_end(id);
1548
1549 // Compute the destination of each Region, and thus each object.
1550 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1551 _summary_data.summarize(_space_info[id].split_info(),
1552 dense_prefix_end, space->top(), NULL,
1553 dense_prefix_end, space->end(),
1554 _space_info[id].new_top_addr());
1555 }
1556 }
1557
1558 if (log_develop_is_enabled(Trace, gc, compaction)) {
1559 const size_t region_size = ParallelCompactData::RegionSize;
1560 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1561 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1562 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1563 HeapWord* const new_top = _space_info[id].new_top();
1564 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1565 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1566 log_develop_trace(gc, compaction)(
1567 "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1568 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1569 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1570 id, space->capacity_in_words(), p2i(dense_prefix_end),
1571 dp_region, dp_words / region_size,
1572 cr_words / region_size, p2i(new_top));
1573 }
1574 }
1575
1576 #ifndef PRODUCT
1577 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1578 HeapWord* dst_beg, HeapWord* dst_end,
1579 SpaceId src_space_id,
1580 HeapWord* src_beg, HeapWord* src_end)
1581 {
1582 log_develop_trace(gc, compaction)(
1583 "Summarizing %d [%s] into %d [%s]: "
1584 "src=" PTR_FORMAT "-" PTR_FORMAT " "
1585 SIZE_FORMAT "-" SIZE_FORMAT " "
1586 "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1587 SIZE_FORMAT "-" SIZE_FORMAT,
1588 src_space_id, space_names[src_space_id],
1589 dst_space_id, space_names[dst_space_id],
1590 p2i(src_beg), p2i(src_end),
1591 _summary_data.addr_to_region_idx(src_beg),
1592 _summary_data.addr_to_region_idx(src_end),
1593 p2i(dst_beg), p2i(dst_end),
1594 _summary_data.addr_to_region_idx(dst_beg),
1595 _summary_data.addr_to_region_idx(dst_end));
1596 }
1597 #endif // #ifndef PRODUCT
1598
1599 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1600 bool maximum_compaction)
1601 {
1602 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer);
1603
1604 #ifdef ASSERT
1605 if (TraceParallelOldGCMarkingPhase) {
1606 tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1607 "add_obj_bytes=" SIZE_FORMAT,
1608 add_obj_count, add_obj_size * HeapWordSize);
1609 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1610 "mark_bitmap_bytes=" SIZE_FORMAT,
1611 mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1612 }
1613 #endif // #ifdef ASSERT
1614
1615 // Quick summarization of each space into itself, to see how much is live.
1616 summarize_spaces_quick();
1617
1618 log_develop_trace(gc, compaction)("summary phase: after summarizing each space to self");
1619 NOT_PRODUCT(print_region_ranges());
1620 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1621
1622 // The amount of live data that will end up in old space (assuming it fits).
1623 size_t old_space_total_live = 0;
1624 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1625 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1626 _space_info[id].space()->bottom());
1627 }
1628
1629 MutableSpace* const old_space = _space_info[old_space_id].space();
1630 const size_t old_capacity = old_space->capacity_in_words();
1631 if (old_space_total_live > old_capacity) {
1632 // XXX - should also try to expand
1633 maximum_compaction = true;
1634 }
1635
1636 // Old generations.
1637 summarize_space(old_space_id, maximum_compaction);
1638
1639 // Summarize the remaining spaces in the young gen. The initial target space
1640 // is the old gen. If a space does not fit entirely into the target, then the
1641 // remainder is compacted into the space itself and that space becomes the new
1642 // target.
1643 SpaceId dst_space_id = old_space_id;
1644 HeapWord* dst_space_end = old_space->end();
1645 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1646 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1647 const MutableSpace* space = _space_info[id].space();
1648 const size_t live = pointer_delta(_space_info[id].new_top(),
1649 space->bottom());
1650 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1651
1652 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1653 SpaceId(id), space->bottom(), space->top());)
1654 if (live > 0 && live <= available) {
1655 // All the live data will fit.
1656 bool done = _summary_data.summarize(_space_info[id].split_info(),
1657 space->bottom(), space->top(),
1658 NULL,
1659 *new_top_addr, dst_space_end,
1660 new_top_addr);
1661 assert(done, "space must fit into old gen");
1662
1663 // Reset the new_top value for the space.
1664 _space_info[id].set_new_top(space->bottom());
1665 } else if (live > 0) {
1666 // Attempt to fit part of the source space into the target space.
1667 HeapWord* next_src_addr = NULL;
1668 bool done = _summary_data.summarize(_space_info[id].split_info(),
1669 space->bottom(), space->top(),
1670 &next_src_addr,
1671 *new_top_addr, dst_space_end,
1672 new_top_addr);
1673 assert(!done, "space should not fit into old gen");
1674 assert(next_src_addr != NULL, "sanity");
1675
1676 // The source space becomes the new target, so the remainder is compacted
1677 // within the space itself.
1678 dst_space_id = SpaceId(id);
1679 dst_space_end = space->end();
1680 new_top_addr = _space_info[id].new_top_addr();
1681 NOT_PRODUCT(summary_phase_msg(dst_space_id,
1682 space->bottom(), dst_space_end,
1683 SpaceId(id), next_src_addr, space->top());)
1684 done = _summary_data.summarize(_space_info[id].split_info(),
1685 next_src_addr, space->top(),
1686 NULL,
1687 space->bottom(), dst_space_end,
1688 new_top_addr);
1689 assert(done, "space must fit when compacted into itself");
1690 assert(*new_top_addr <= space->top(), "usage should not grow");
1691 }
1692 }
1693
1694 log_develop_trace(gc, compaction)("Summary_phase: after final summarization");
1695 NOT_PRODUCT(print_region_ranges());
1696 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1697 }
1698
1699 // This method should contain all heap-specific policy for invoking a full
1700 // collection. invoke_no_policy() will only attempt to compact the heap; it
1701 // will do nothing further. If we need to bail out for policy reasons, scavenge
1702 // before full gc, or any other specialized behavior, it needs to be added here.
1703 //
1704 // Note that this method should only be called from the vm_thread while at a
1705 // safepoint.
1706 //
1707 // Note that the all_soft_refs_clear flag in the collector policy
1708 // may be true because this method can be called without intervening
1709 // activity. For example when the heap space is tight and full measure
1710 // are being taken to free space.
1711 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1712 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1713 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1714 "should be in vm thread");
1715
1716 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1717 GCCause::Cause gc_cause = heap->gc_cause();
1718 assert(!heap->is_gc_active(), "not reentrant");
1719
1720 PSAdaptiveSizePolicy* policy = heap->size_policy();
1721 IsGCActiveMark mark;
1722
1723 if (ScavengeBeforeFullGC) {
1724 PSScavenge::invoke_no_policy();
1725 }
1726
1727 const bool clear_all_soft_refs =
1728 heap->collector_policy()->should_clear_all_soft_refs();
1729
1730 PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1731 maximum_heap_compaction);
1732 }
1733
1734 // This method contains no policy. You should probably
1735 // be calling invoke() instead.
1736 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1737 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1738 assert(ref_processor() != NULL, "Sanity");
1739
1740 if (GCLocker::check_active_before_gc()) {
1741 return false;
1742 }
1743
1744 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1745
1746 GCIdMark gc_id_mark;
1747 _gc_timer.register_gc_start();
1748 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
1749
1750 TimeStamp marking_start;
1751 TimeStamp compaction_start;
1752 TimeStamp collection_exit;
1753
1754 GCCause::Cause gc_cause = heap->gc_cause();
1755 PSYoungGen* young_gen = heap->young_gen();
1756 PSOldGen* old_gen = heap->old_gen();
1757 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1758
1759 // The scope of casr should end after code that can change
1760 // CollectorPolicy::_should_clear_all_soft_refs.
1761 ClearedAllSoftRefs casr(maximum_heap_compaction,
1762 heap->collector_policy());
1763
1764 if (ZapUnusedHeapArea) {
1765 // Save information needed to minimize mangling
1766 heap->record_gen_tops_before_GC();
1767 }
1768
1769 // Make sure data structures are sane, make the heap parsable, and do other
1770 // miscellaneous bookkeeping.
1771 pre_compact();
1772
1773 PreGCValues pre_gc_values(heap);
1774
1775 // Get the compaction manager reserved for the VM thread.
1776 ParCompactionManager* const vmthread_cm =
1777 ParCompactionManager::manager_array(gc_task_manager()->workers());
1778
1779 {
1780 ResourceMark rm;
1781 HandleMark hm;
1782
1783 // Set the number of GC threads to be used in this collection
1784 gc_task_manager()->set_active_gang();
1785 gc_task_manager()->task_idle_workers();
1786
1787 GCTraceCPUTime tcpu;
1788 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause, true);
1789
1790 heap->pre_full_gc_dump(&_gc_timer);
1791
1792 TraceCollectorStats tcs(counters());
1793 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
1794
1795 if (TraceOldGenTime) accumulated_time()->start();
1796
1797 // Let the size policy know we're starting
1798 size_policy->major_collection_begin();
1799
1800 CodeCache::gc_prologue();
1801
1802 #if defined(COMPILER2) || INCLUDE_JVMCI
1803 DerivedPointerTable::clear();
1804 #endif
1805
1806 ref_processor()->enable_discovery();
1807 ref_processor()->setup_policy(maximum_heap_compaction);
1808
1809 bool marked_for_unloading = false;
1810
1811 marking_start.update();
1812 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer);
1813
1814 bool max_on_system_gc = UseMaximumCompactionOnSystemGC
1815 && GCCause::is_user_requested_gc(gc_cause);
1816 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
1817
1818 #if defined(COMPILER2) || INCLUDE_JVMCI
1819 assert(DerivedPointerTable::is_active(), "Sanity");
1820 DerivedPointerTable::set_active(false);
1821 #endif
1822
1823 // adjust_roots() updates Universe::_intArrayKlassObj which is
1824 // needed by the compaction for filling holes in the dense prefix.
1825 adjust_roots(vmthread_cm);
1826
1827 compaction_start.update();
1828 compact();
1829
1830 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
1831 // done before resizing.
1832 post_compact();
1833
1834 // Let the size policy know we're done
1835 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
1836
1837 if (UseAdaptiveSizePolicy) {
1838 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
1839 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
1840 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
1841
1842 // Don't check if the size_policy is ready here. Let
1843 // the size_policy check that internally.
1844 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
1845 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
1846 // Swap the survivor spaces if from_space is empty. The
1847 // resize_young_gen() called below is normally used after
1848 // a successful young GC and swapping of survivor spaces;
1849 // otherwise, it will fail to resize the young gen with
1850 // the current implementation.
1851 if (young_gen->from_space()->is_empty()) {
1852 young_gen->from_space()->clear(SpaceDecorator::Mangle);
1853 young_gen->swap_spaces();
1854 }
1855
1856 // Calculate optimal free space amounts
1857 assert(young_gen->max_size() >
1858 young_gen->from_space()->capacity_in_bytes() +
1859 young_gen->to_space()->capacity_in_bytes(),
1860 "Sizes of space in young gen are out-of-bounds");
1861
1862 size_t young_live = young_gen->used_in_bytes();
1863 size_t eden_live = young_gen->eden_space()->used_in_bytes();
1864 size_t old_live = old_gen->used_in_bytes();
1865 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
1866 size_t max_old_gen_size = old_gen->max_gen_size();
1867 size_t max_eden_size = young_gen->max_size() -
1868 young_gen->from_space()->capacity_in_bytes() -
1869 young_gen->to_space()->capacity_in_bytes();
1870
1871 // Used for diagnostics
1872 size_policy->clear_generation_free_space_flags();
1873
1874 size_policy->compute_generations_free_space(young_live,
1875 eden_live,
1876 old_live,
1877 cur_eden,
1878 max_old_gen_size,
1879 max_eden_size,
1880 true /* full gc*/);
1881
1882 size_policy->check_gc_overhead_limit(young_live,
1883 eden_live,
1884 max_old_gen_size,
1885 max_eden_size,
1886 true /* full gc*/,
1887 gc_cause,
1888 heap->collector_policy());
1889
1890 size_policy->decay_supplemental_growth(true /* full gc*/);
1891
1892 heap->resize_old_gen(
1893 size_policy->calculated_old_free_size_in_bytes());
1894
1895 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
1896 size_policy->calculated_survivor_size_in_bytes());
1897 }
1898
1899 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
1900 }
1901
1902 if (UsePerfData) {
1903 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
1904 counters->update_counters();
1905 counters->update_old_capacity(old_gen->capacity_in_bytes());
1906 counters->update_young_capacity(young_gen->capacity_in_bytes());
1907 }
1908
1909 heap->resize_all_tlabs();
1910
1911 // Resize the metaspace capacity after a collection
1912 MetaspaceGC::compute_new_size();
1913
1914 if (TraceOldGenTime) {
1915 accumulated_time()->stop();
1916 }
1917
1918 young_gen->print_used_change(pre_gc_values.young_gen_used());
1919 old_gen->print_used_change(pre_gc_values.old_gen_used());
1920 MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used());
1921
1922 // Track memory usage and detect low memory
1923 MemoryService::track_memory_usage();
1924 heap->update_counters();
1925 gc_task_manager()->release_idle_workers();
1926
1927 heap->post_full_gc_dump(&_gc_timer);
1928 }
1929
1930 #ifdef ASSERT
1931 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
1932 ParCompactionManager* const cm =
1933 ParCompactionManager::manager_array(int(i));
1934 assert(cm->marking_stack()->is_empty(), "should be empty");
1935 assert(cm->region_stack()->is_empty(), "Region stack " SIZE_FORMAT " is not empty", i);
1936 }
1937 #endif // ASSERT
1938
1939 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1940 HandleMark hm; // Discard invalid handles created during verification
1941 Universe::verify("After GC");
1942 }
1943
1944 // Re-verify object start arrays
1945 if (VerifyObjectStartArray &&
1946 VerifyAfterGC) {
1947 old_gen->verify_object_start_array();
1948 }
1949
1950 if (ZapUnusedHeapArea) {
1951 old_gen->object_space()->check_mangled_unused_area_complete();
1952 }
1953
1954 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1955
1956 collection_exit.update();
1957
1958 heap->print_heap_after_gc();
1959 heap->trace_heap_after_gc(&_gc_tracer);
1960
1961 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT,
1962 marking_start.ticks(), compaction_start.ticks(),
1963 collection_exit.ticks());
1964 gc_task_manager()->print_task_time_stamps();
1965
1966 #ifdef TRACESPINNING
1967 ParallelTaskTerminator::print_termination_counts();
1968 #endif
1969
1970 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
1971
1972 _gc_timer.register_gc_end();
1973
1974 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
1975 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
1976
1977 return true;
1978 }
1979
1980 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
1981 PSYoungGen* young_gen,
1982 PSOldGen* old_gen) {
1983 MutableSpace* const eden_space = young_gen->eden_space();
1984 assert(!eden_space->is_empty(), "eden must be non-empty");
1985 assert(young_gen->virtual_space()->alignment() ==
1986 old_gen->virtual_space()->alignment(), "alignments do not match");
1987
1988 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
1989 return false;
1990 }
1991
1992 // Both generations must be completely committed.
1993 if (young_gen->virtual_space()->uncommitted_size() != 0) {
1994 return false;
1995 }
1996 if (old_gen->virtual_space()->uncommitted_size() != 0) {
1997 return false;
1998 }
1999
2000 // Figure out how much to take from eden. Include the average amount promoted
2001 // in the total; otherwise the next young gen GC will simply bail out to a
2002 // full GC.
2003 const size_t alignment = old_gen->virtual_space()->alignment();
2004 const size_t eden_used = eden_space->used_in_bytes();
2005 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
2006 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
2007 const size_t eden_capacity = eden_space->capacity_in_bytes();
2008
2009 if (absorb_size >= eden_capacity) {
2010 return false; // Must leave some space in eden.
2011 }
2012
2013 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2014 if (new_young_size < young_gen->min_gen_size()) {
2015 return false; // Respect young gen minimum size.
2016 }
2017
2018 log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K: "
2019 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2020 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2021 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2022 absorb_size / K,
2023 eden_capacity / K, (eden_capacity - absorb_size) / K,
2024 young_gen->from_space()->used_in_bytes() / K,
2025 young_gen->to_space()->used_in_bytes() / K,
2026 young_gen->capacity_in_bytes() / K, new_young_size / K);
2027
2028 // Fill the unused part of the old gen.
2029 MutableSpace* const old_space = old_gen->object_space();
2030 HeapWord* const unused_start = old_space->top();
2031 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2032
2033 if (unused_words > 0) {
2034 if (unused_words < CollectedHeap::min_fill_size()) {
2035 return false; // If the old gen cannot be filled, must give up.
2036 }
2037 CollectedHeap::fill_with_objects(unused_start, unused_words);
2038 }
2039
2040 // Take the live data from eden and set both top and end in the old gen to
2041 // eden top. (Need to set end because reset_after_change() mangles the region
2042 // from end to virtual_space->high() in debug builds).
2043 HeapWord* const new_top = eden_space->top();
2044 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2045 absorb_size);
2046 young_gen->reset_after_change();
2047 old_space->set_top(new_top);
2048 old_space->set_end(new_top);
2049 old_gen->reset_after_change();
2050
2051 // Update the object start array for the filler object and the data from eden.
2052 ObjectStartArray* const start_array = old_gen->start_array();
2053 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2054 start_array->allocate_block(p);
2055 }
2056
2057 // Could update the promoted average here, but it is not typically updated at
2058 // full GCs and the value to use is unclear. Something like
2059 //
2060 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2061
2062 size_policy->set_bytes_absorbed_from_eden(absorb_size);
2063 return true;
2064 }
2065
2066 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2067 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2068 "shouldn't return NULL");
2069 return ParallelScavengeHeap::gc_task_manager();
2070 }
2071
2072 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2073 bool maximum_heap_compaction,
2074 ParallelOldTracer *gc_tracer) {
2075 // Recursively traverse all live objects and mark them
2076 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer);
2077
2078 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2079 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2080 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2081 TaskQueueSetSuper* qset = ParCompactionManager::stack_array();
2082 ParallelTaskTerminator terminator(active_gc_threads, qset);
2083
2084 ParCompactionManager::MarkAndPushClosure mark_and_push_closure(cm);
2085 ParCompactionManager::FollowStackClosure follow_stack_closure(cm);
2086
2087 // Need new claim bits before marking starts.
2088 ClassLoaderDataGraph::clear_claimed_marks();
2089
2090 {
2091 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer);
2092
2093 ParallelScavengeHeap::ParStrongRootsScope psrs;
2094
2095 GCTaskQueue* q = GCTaskQueue::create();
2096
2097 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2098 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2099 // We scan the thread roots in parallel
2100 Threads::create_thread_roots_marking_tasks(q);
2101 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2102 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
2103 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2104 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2105 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data));
2106 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2107 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2108
2109 if (active_gc_threads > 1) {
2110 for (uint j = 0; j < active_gc_threads; j++) {
2111 q->enqueue(new StealMarkingTask(&terminator));
2112 }
2113 }
2114
2115 gc_task_manager()->execute_and_wait(q);
2116 }
2117
2118 // Process reference objects found during marking
2119 {
2120 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
2121
2122 ReferenceProcessorStats stats;
2123 if (ref_processor()->processing_is_mt()) {
2124 RefProcTaskExecutor task_executor;
2125 stats = ref_processor()->process_discovered_references(
2126 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2127 &task_executor, &_gc_timer);
2128 } else {
2129 stats = ref_processor()->process_discovered_references(
2130 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
2131 &_gc_timer);
2132 }
2133
2134 gc_tracer->report_gc_reference_stats(stats);
2135 }
2136
2137 // This is the point where the entire marking should have completed.
2138 assert(cm->marking_stacks_empty(), "Marking should have completed");
2139
2140 {
2141 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer);
2142
2143 // Follow system dictionary roots and unload classes.
2144 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
2145
2146 // Unload nmethods.
2147 CodeCache::do_unloading(is_alive_closure(), purged_class);
2148
2149 // Prune dead klasses from subklass/sibling/implementor lists.
2150 Klass::clean_weak_klass_links(is_alive_closure());
2151 }
2152
2153 {
2154 GCTraceTime(Debug, gc, phases) t("Scrub String Table", &_gc_timer);
2155 // Delete entries for dead interned strings.
2156 StringTable::unlink(is_alive_closure());
2157 }
2158
2159 {
2160 GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", &_gc_timer);
2161 // Clean up unreferenced symbols in symbol table.
2162 SymbolTable::unlink();
2163 }
2164
2165 _gc_tracer.report_object_count_after_gc(is_alive_closure());
2166 }
2167
2168 void PSParallelCompact::adjust_roots(ParCompactionManager* cm) {
2169 // Adjust the pointers to reflect the new locations
2170 GCTraceTime(Info, gc, phases) tm("Adjust Roots", &_gc_timer);
2171
2172 // Need new claim bits when tracing through and adjusting pointers.
2173 ClassLoaderDataGraph::clear_claimed_marks();
2174
2175 PSParallelCompact::AdjustPointerClosure oop_closure(cm);
2176 PSParallelCompact::AdjustKlassClosure klass_closure(cm);
2177
2178 // General strong roots.
2179 Universe::oops_do(&oop_closure);
2180 JNIHandles::oops_do(&oop_closure); // Global (strong) JNI handles
2181 Threads::oops_do(&oop_closure, NULL);
2182 ObjectSynchronizer::oops_do(&oop_closure);
2183 FlatProfiler::oops_do(&oop_closure);
2184 Management::oops_do(&oop_closure);
2185 JvmtiExport::oops_do(&oop_closure);
2186 SystemDictionary::oops_do(&oop_closure);
2187 ClassLoaderDataGraph::oops_do(&oop_closure, &klass_closure, true);
2188
2189 // Now adjust pointers in remaining weak roots. (All of which should
2190 // have been cleared if they pointed to non-surviving objects.)
2191 // Global (weak) JNI handles
2192 JNIHandles::weak_oops_do(&oop_closure);
2193
2194 CodeBlobToOopClosure adjust_from_blobs(&oop_closure, CodeBlobToOopClosure::FixRelocations);
2195 CodeCache::blobs_do(&adjust_from_blobs);
2196 StringTable::oops_do(&oop_closure);
2197 ref_processor()->weak_oops_do(&oop_closure);
2198 // Roots were visited so references into the young gen in roots
2199 // may have been scanned. Process them also.
2200 // Should the reference processor have a span that excludes
2201 // young gen objects?
2202 PSScavenge::reference_processor()->weak_oops_do(&oop_closure);
2203 }
2204
2205 // Helper class to print 8 region numbers per line and then print the total at the end.
2206 class FillableRegionLogger : public StackObj {
2207 private:
2208 Log(gc, compaction) log;
2209 static const int LineLength = 8;
2210 size_t _regions[LineLength];
2211 int _next_index;
2212 bool _enabled;
2213 size_t _total_regions;
2214 public:
2215 FillableRegionLogger() : _next_index(0), _total_regions(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)) { }
2216 ~FillableRegionLogger() {
2217 log.trace(SIZE_FORMAT " initially fillable regions", _total_regions);
2218 }
2219
2220 void print_line() {
2221 if (!_enabled || _next_index == 0) {
2222 return;
2223 }
2224 FormatBuffer<> line("Fillable: ");
2225 for (int i = 0; i < _next_index; i++) {
2226 line.append(" " SIZE_FORMAT_W(7), _regions[i]);
2227 }
2228 log.trace("%s", line.buffer());
2229 _next_index = 0;
2230 }
2231
2232 void handle(size_t region) {
2233 if (!_enabled) {
2234 return;
2235 }
2236 _regions[_next_index++] = region;
2237 if (_next_index == LineLength) {
2238 print_line();
2239 }
2240 _total_regions++;
2241 }
2242 };
2243
2244 void PSParallelCompact::prepare_region_draining_tasks(GCTaskQueue* q,
2245 uint parallel_gc_threads)
2246 {
2247 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer);
2248
2249 // Find the threads that are active
2250 unsigned int which = 0;
2251
2252 // Find all regions that are available (can be filled immediately) and
2253 // distribute them to the thread stacks. The iteration is done in reverse
2254 // order (high to low) so the regions will be removed in ascending order.
2255
2256 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2257
2258 which = 0;
2259 // id + 1 is used to test termination so unsigned can
2260 // be used with an old_space_id == 0.
2261 FillableRegionLogger region_logger;
2262 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2263 SpaceInfo* const space_info = _space_info + id;
2264 MutableSpace* const space = space_info->space();
2265 HeapWord* const new_top = space_info->new_top();
2266
2267 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2268 const size_t end_region =
2269 sd.addr_to_region_idx(sd.region_align_up(new_top));
2270
2271 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2272 if (sd.region(cur)->claim_unsafe()) {
2273 ParCompactionManager* cm = ParCompactionManager::manager_array(which);
2274 cm->region_stack()->push(cur);
2275 region_logger.handle(cur);
2276 // Assign regions to tasks in round-robin fashion.
2277 if (++which == parallel_gc_threads) {
2278 which = 0;
2279 }
2280 }
2281 }
2282 region_logger.print_line();
2283 }
2284 }
2285
2286 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2287
2288 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2289 uint parallel_gc_threads) {
2290 GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer);
2291
2292 ParallelCompactData& sd = PSParallelCompact::summary_data();
2293
2294 // Iterate over all the spaces adding tasks for updating
2295 // regions in the dense prefix. Assume that 1 gc thread
2296 // will work on opening the gaps and the remaining gc threads
2297 // will work on the dense prefix.
2298 unsigned int space_id;
2299 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2300 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2301 const MutableSpace* const space = _space_info[space_id].space();
2302
2303 if (dense_prefix_end == space->bottom()) {
2304 // There is no dense prefix for this space.
2305 continue;
2306 }
2307
2308 // The dense prefix is before this region.
2309 size_t region_index_end_dense_prefix =
2310 sd.addr_to_region_idx(dense_prefix_end);
2311 RegionData* const dense_prefix_cp =
2312 sd.region(region_index_end_dense_prefix);
2313 assert(dense_prefix_end == space->end() ||
2314 dense_prefix_cp->available() ||
2315 dense_prefix_cp->claimed(),
2316 "The region after the dense prefix should always be ready to fill");
2317
2318 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2319
2320 // Is there dense prefix work?
2321 size_t total_dense_prefix_regions =
2322 region_index_end_dense_prefix - region_index_start;
2323 // How many regions of the dense prefix should be given to
2324 // each thread?
2325 if (total_dense_prefix_regions > 0) {
2326 uint tasks_for_dense_prefix = 1;
2327 if (total_dense_prefix_regions <=
2328 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2329 // Don't over partition. This assumes that
2330 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2331 // so there are not many regions to process.
2332 tasks_for_dense_prefix = parallel_gc_threads;
2333 } else {
2334 // Over partition
2335 tasks_for_dense_prefix = parallel_gc_threads *
2336 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2337 }
2338 size_t regions_per_thread = total_dense_prefix_regions /
2339 tasks_for_dense_prefix;
2340 // Give each thread at least 1 region.
2341 if (regions_per_thread == 0) {
2342 regions_per_thread = 1;
2343 }
2344
2345 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2346 if (region_index_start >= region_index_end_dense_prefix) {
2347 break;
2348 }
2349 // region_index_end is not processed
2350 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2351 region_index_end_dense_prefix);
2352 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2353 region_index_start,
2354 region_index_end));
2355 region_index_start = region_index_end;
2356 }
2357 }
2358 // This gets any part of the dense prefix that did not
2359 // fit evenly.
2360 if (region_index_start < region_index_end_dense_prefix) {
2361 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2362 region_index_start,
2363 region_index_end_dense_prefix));
2364 }
2365 }
2366 }
2367
2368 void PSParallelCompact::enqueue_region_stealing_tasks(
2369 GCTaskQueue* q,
2370 ParallelTaskTerminator* terminator_ptr,
2371 uint parallel_gc_threads) {
2372 GCTraceTime(Trace, gc, phases) tm("Steal Task Setup", &_gc_timer);
2373
2374 // Once a thread has drained it's stack, it should try to steal regions from
2375 // other threads.
2376 for (uint j = 0; j < parallel_gc_threads; j++) {
2377 q->enqueue(new StealRegionCompactionTask(terminator_ptr));
2378 }
2379 }
2380
2381 #ifdef ASSERT
2382 // Write a histogram of the number of times the block table was filled for a
2383 // region.
2384 void PSParallelCompact::write_block_fill_histogram()
2385 {
2386 if (!log_develop_is_enabled(Trace, gc, compaction)) {
2387 return;
2388 }
2389
2390 Log(gc, compaction) log;
2391 ResourceMark rm;
2392 outputStream* out = log.trace_stream();
2393
2394 typedef ParallelCompactData::RegionData rd_t;
2395 ParallelCompactData& sd = summary_data();
2396
2397 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2398 MutableSpace* const spc = _space_info[id].space();
2399 if (spc->bottom() != spc->top()) {
2400 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
2401 HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
2402 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
2403
2404 size_t histo[5] = { 0, 0, 0, 0, 0 };
2405 const size_t histo_len = sizeof(histo) / sizeof(size_t);
2406 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
2407
2408 for (const rd_t* cur = beg; cur < end; ++cur) {
2409 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
2410 }
2411 out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
2412 for (size_t i = 0; i < histo_len; ++i) {
2413 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
2414 histo[i], 100.0 * histo[i] / region_cnt);
2415 }
2416 out->cr();
2417 }
2418 }
2419 }
2420 #endif // #ifdef ASSERT
2421
2422 void PSParallelCompact::compact() {
2423 GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer);
2424
2425 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2426 PSOldGen* old_gen = heap->old_gen();
2427 old_gen->start_array()->reset();
2428 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2429 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2430 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2431 ParallelTaskTerminator terminator(active_gc_threads, qset);
2432
2433 GCTaskQueue* q = GCTaskQueue::create();
2434 prepare_region_draining_tasks(q, active_gc_threads);
2435 enqueue_dense_prefix_tasks(q, active_gc_threads);
2436 enqueue_region_stealing_tasks(q, &terminator, active_gc_threads);
2437
2438 {
2439 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer);
2440
2441 gc_task_manager()->execute_and_wait(q);
2442
2443 #ifdef ASSERT
2444 // Verify that all regions have been processed before the deferred updates.
2445 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2446 verify_complete(SpaceId(id));
2447 }
2448 #endif
2449 }
2450
2451 {
2452 // Update the deferred objects, if any. Any compaction manager can be used.
2453 GCTraceTime(Trace, gc, phases) tm("Deferred Updates", &_gc_timer);
2454 ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2455 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2456 update_deferred_objects(cm, SpaceId(id));
2457 }
2458 }
2459
2460 DEBUG_ONLY(write_block_fill_histogram());
2461 }
2462
2463 #ifdef ASSERT
2464 void PSParallelCompact::verify_complete(SpaceId space_id) {
2465 // All Regions between space bottom() to new_top() should be marked as filled
2466 // and all Regions between new_top() and top() should be available (i.e.,
2467 // should have been emptied).
2468 ParallelCompactData& sd = summary_data();
2469 SpaceInfo si = _space_info[space_id];
2470 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2471 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2472 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2473 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2474 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2475
2476 bool issued_a_warning = false;
2477
2478 size_t cur_region;
2479 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2480 const RegionData* const c = sd.region(cur_region);
2481 if (!c->completed()) {
2482 log_warning(gc)("region " SIZE_FORMAT " not filled: destination_count=%u",
2483 cur_region, c->destination_count());
2484 issued_a_warning = true;
2485 }
2486 }
2487
2488 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2489 const RegionData* const c = sd.region(cur_region);
2490 if (!c->available()) {
2491 log_warning(gc)("region " SIZE_FORMAT " not empty: destination_count=%u",
2492 cur_region, c->destination_count());
2493 issued_a_warning = true;
2494 }
2495 }
2496
2497 if (issued_a_warning) {
2498 print_region_ranges();
2499 }
2500 }
2501 #endif // #ifdef ASSERT
2502
2503 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) {
2504 _start_array->allocate_block(addr);
2505 compaction_manager()->update_contents(oop(addr));
2506 }
2507
2508 // Update interior oops in the ranges of regions [beg_region, end_region).
2509 void
2510 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2511 SpaceId space_id,
2512 size_t beg_region,
2513 size_t end_region) {
2514 ParallelCompactData& sd = summary_data();
2515 ParMarkBitMap* const mbm = mark_bitmap();
2516
2517 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2518 HeapWord* const end_addr = sd.region_to_addr(end_region);
2519 assert(beg_region <= end_region, "bad region range");
2520 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2521
2522 #ifdef ASSERT
2523 // Claim the regions to avoid triggering an assert when they are marked as
2524 // filled.
2525 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2526 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2527 }
2528 #endif // #ifdef ASSERT
2529
2530 if (beg_addr != space(space_id)->bottom()) {
2531 // Find the first live object or block of dead space that *starts* in this
2532 // range of regions. If a partial object crosses onto the region, skip it;
2533 // it will be marked for 'deferred update' when the object head is
2534 // processed. If dead space crosses onto the region, it is also skipped; it
2535 // will be filled when the prior region is processed. If neither of those
2536 // apply, the first word in the region is the start of a live object or dead
2537 // space.
2538 assert(beg_addr > space(space_id)->bottom(), "sanity");
2539 const RegionData* const cp = sd.region(beg_region);
2540 if (cp->partial_obj_size() != 0) {
2541 beg_addr = sd.partial_obj_end(beg_region);
2542 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2543 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2544 }
2545 }
2546
2547 if (beg_addr < end_addr) {
2548 // A live object or block of dead space starts in this range of Regions.
2549 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2550
2551 // Create closures and iterate.
2552 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2553 FillClosure fill_closure(cm, space_id);
2554 ParMarkBitMap::IterationStatus status;
2555 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2556 dense_prefix_end);
2557 if (status == ParMarkBitMap::incomplete) {
2558 update_closure.do_addr(update_closure.source());
2559 }
2560 }
2561
2562 // Mark the regions as filled.
2563 RegionData* const beg_cp = sd.region(beg_region);
2564 RegionData* const end_cp = sd.region(end_region);
2565 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2566 cp->set_completed();
2567 }
2568 }
2569
2570 // Return the SpaceId for the space containing addr. If addr is not in the
2571 // heap, last_space_id is returned. In debug mode it expects the address to be
2572 // in the heap and asserts such.
2573 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2574 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
2575
2576 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2577 if (_space_info[id].space()->contains(addr)) {
2578 return SpaceId(id);
2579 }
2580 }
2581
2582 assert(false, "no space contains the addr");
2583 return last_space_id;
2584 }
2585
2586 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2587 SpaceId id) {
2588 assert(id < last_space_id, "bad space id");
2589
2590 ParallelCompactData& sd = summary_data();
2591 const SpaceInfo* const space_info = _space_info + id;
2592 ObjectStartArray* const start_array = space_info->start_array();
2593
2594 const MutableSpace* const space = space_info->space();
2595 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2596 HeapWord* const beg_addr = space_info->dense_prefix();
2597 HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2598
2599 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2600 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2601 const RegionData* cur_region;
2602 for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2603 HeapWord* const addr = cur_region->deferred_obj_addr();
2604 if (addr != NULL) {
2605 if (start_array != NULL) {
2606 start_array->allocate_block(addr);
2607 }
2608 cm->update_contents(oop(addr));
2609 assert(oop(addr)->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(addr)));
2610 }
2611 }
2612 }
2613
2614 // Skip over count live words starting from beg, and return the address of the
2615 // next live word. Unless marked, the word corresponding to beg is assumed to
2616 // be dead. Callers must either ensure beg does not correspond to the middle of
2617 // an object, or account for those live words in some other way. Callers must
2618 // also ensure that there are enough live words in the range [beg, end) to skip.
2619 HeapWord*
2620 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2621 {
2622 assert(count > 0, "sanity");
2623
2624 ParMarkBitMap* m = mark_bitmap();
2625 idx_t bits_to_skip = m->words_to_bits(count);
2626 idx_t cur_beg = m->addr_to_bit(beg);
2627 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
2628
2629 do {
2630 cur_beg = m->find_obj_beg(cur_beg, search_end);
2631 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2632 const size_t obj_bits = cur_end - cur_beg + 1;
2633 if (obj_bits > bits_to_skip) {
2634 return m->bit_to_addr(cur_beg + bits_to_skip);
2635 }
2636 bits_to_skip -= obj_bits;
2637 cur_beg = cur_end + 1;
2638 } while (bits_to_skip > 0);
2639
2640 // Skipping the desired number of words landed just past the end of an object.
2641 // Find the start of the next object.
2642 cur_beg = m->find_obj_beg(cur_beg, search_end);
2643 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2644 return m->bit_to_addr(cur_beg);
2645 }
2646
2647 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2648 SpaceId src_space_id,
2649 size_t src_region_idx)
2650 {
2651 assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2652
2653 const SplitInfo& split_info = _space_info[src_space_id].split_info();
2654 if (split_info.dest_region_addr() == dest_addr) {
2655 // The partial object ending at the split point contains the first word to
2656 // be copied to dest_addr.
2657 return split_info.first_src_addr();
2658 }
2659
2660 const ParallelCompactData& sd = summary_data();
2661 ParMarkBitMap* const bitmap = mark_bitmap();
2662 const size_t RegionSize = ParallelCompactData::RegionSize;
2663
2664 assert(sd.is_region_aligned(dest_addr), "not aligned");
2665 const RegionData* const src_region_ptr = sd.region(src_region_idx);
2666 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2667 HeapWord* const src_region_destination = src_region_ptr->destination();
2668
2669 assert(dest_addr >= src_region_destination, "wrong src region");
2670 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2671
2672 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2673 HeapWord* const src_region_end = src_region_beg + RegionSize;
2674
2675 HeapWord* addr = src_region_beg;
2676 if (dest_addr == src_region_destination) {
2677 // Return the first live word in the source region.
2678 if (partial_obj_size == 0) {
2679 addr = bitmap->find_obj_beg(addr, src_region_end);
2680 assert(addr < src_region_end, "no objects start in src region");
2681 }
2682 return addr;
2683 }
2684
2685 // Must skip some live data.
2686 size_t words_to_skip = dest_addr - src_region_destination;
2687 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2688
2689 if (partial_obj_size >= words_to_skip) {
2690 // All the live words to skip are part of the partial object.
2691 addr += words_to_skip;
2692 if (partial_obj_size == words_to_skip) {
2693 // Find the first live word past the partial object.
2694 addr = bitmap->find_obj_beg(addr, src_region_end);
2695 assert(addr < src_region_end, "wrong src region");
2696 }
2697 return addr;
2698 }
2699
2700 // Skip over the partial object (if any).
2701 if (partial_obj_size != 0) {
2702 words_to_skip -= partial_obj_size;
2703 addr += partial_obj_size;
2704 }
2705
2706 // Skip over live words due to objects that start in the region.
2707 addr = skip_live_words(addr, src_region_end, words_to_skip);
2708 assert(addr < src_region_end, "wrong src region");
2709 return addr;
2710 }
2711
2712 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2713 SpaceId src_space_id,
2714 size_t beg_region,
2715 HeapWord* end_addr)
2716 {
2717 ParallelCompactData& sd = summary_data();
2718
2719 #ifdef ASSERT
2720 MutableSpace* const src_space = _space_info[src_space_id].space();
2721 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2722 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2723 "src_space_id does not match beg_addr");
2724 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2725 "src_space_id does not match end_addr");
2726 #endif // #ifdef ASSERT
2727
2728 RegionData* const beg = sd.region(beg_region);
2729 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2730
2731 // Regions up to new_top() are enqueued if they become available.
2732 HeapWord* const new_top = _space_info[src_space_id].new_top();
2733 RegionData* const enqueue_end =
2734 sd.addr_to_region_ptr(sd.region_align_up(new_top));
2735
2736 for (RegionData* cur = beg; cur < end; ++cur) {
2737 assert(cur->data_size() > 0, "region must have live data");
2738 cur->decrement_destination_count();
2739 if (cur < enqueue_end && cur->available() && cur->claim()) {
2740 cm->push_region(sd.region(cur));
2741 }
2742 }
2743 }
2744
2745 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2746 SpaceId& src_space_id,
2747 HeapWord*& src_space_top,
2748 HeapWord* end_addr)
2749 {
2750 typedef ParallelCompactData::RegionData RegionData;
2751
2752 ParallelCompactData& sd = PSParallelCompact::summary_data();
2753 const size_t region_size = ParallelCompactData::RegionSize;
2754
2755 size_t src_region_idx = 0;
2756
2757 // Skip empty regions (if any) up to the top of the space.
2758 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2759 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2760 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2761 const RegionData* const top_region_ptr =
2762 sd.addr_to_region_ptr(top_aligned_up);
2763 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2764 ++src_region_ptr;
2765 }
2766
2767 if (src_region_ptr < top_region_ptr) {
2768 // The next source region is in the current space. Update src_region_idx
2769 // and the source address to match src_region_ptr.
2770 src_region_idx = sd.region(src_region_ptr);
2771 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
2772 if (src_region_addr > closure.source()) {
2773 closure.set_source(src_region_addr);
2774 }
2775 return src_region_idx;
2776 }
2777
2778 // Switch to a new source space and find the first non-empty region.
2779 unsigned int space_id = src_space_id + 1;
2780 assert(space_id < last_space_id, "not enough spaces");
2781
2782 HeapWord* const destination = closure.destination();
2783
2784 do {
2785 MutableSpace* space = _space_info[space_id].space();
2786 HeapWord* const bottom = space->bottom();
2787 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
2788
2789 // Iterate over the spaces that do not compact into themselves.
2790 if (bottom_cp->destination() != bottom) {
2791 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
2792 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
2793
2794 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
2795 if (src_cp->live_obj_size() > 0) {
2796 // Found it.
2797 assert(src_cp->destination() == destination,
2798 "first live obj in the space must match the destination");
2799 assert(src_cp->partial_obj_size() == 0,
2800 "a space cannot begin with a partial obj");
2801
2802 src_space_id = SpaceId(space_id);
2803 src_space_top = space->top();
2804 const size_t src_region_idx = sd.region(src_cp);
2805 closure.set_source(sd.region_to_addr(src_region_idx));
2806 return src_region_idx;
2807 } else {
2808 assert(src_cp->data_size() == 0, "sanity");
2809 }
2810 }
2811 }
2812 } while (++space_id < last_space_id);
2813
2814 assert(false, "no source region was found");
2815 return 0;
2816 }
2817
2818 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
2819 {
2820 typedef ParMarkBitMap::IterationStatus IterationStatus;
2821 const size_t RegionSize = ParallelCompactData::RegionSize;
2822 ParMarkBitMap* const bitmap = mark_bitmap();
2823 ParallelCompactData& sd = summary_data();
2824 RegionData* const region_ptr = sd.region(region_idx);
2825
2826 // Get the items needed to construct the closure.
2827 HeapWord* dest_addr = sd.region_to_addr(region_idx);
2828 SpaceId dest_space_id = space_id(dest_addr);
2829 ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
2830 HeapWord* new_top = _space_info[dest_space_id].new_top();
2831 assert(dest_addr < new_top, "sanity");
2832 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
2833
2834 // Get the source region and related info.
2835 size_t src_region_idx = region_ptr->source_region();
2836 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2837 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2838
2839 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
2840 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2841
2842 // Adjust src_region_idx to prepare for decrementing destination counts (the
2843 // destination count is not decremented when a region is copied to itself).
2844 if (src_region_idx == region_idx) {
2845 src_region_idx += 1;
2846 }
2847
2848 if (bitmap->is_unmarked(closure.source())) {
2849 // The first source word is in the middle of an object; copy the remainder
2850 // of the object or as much as will fit. The fact that pointer updates were
2851 // deferred will be noted when the object header is processed.
2852 HeapWord* const old_src_addr = closure.source();
2853 closure.copy_partial_obj();
2854 if (closure.is_full()) {
2855 decrement_destination_counts(cm, src_space_id, src_region_idx,
2856 closure.source());
2857 region_ptr->set_deferred_obj_addr(NULL);
2858 region_ptr->set_completed();
2859 return;
2860 }
2861
2862 HeapWord* const end_addr = sd.region_align_down(closure.source());
2863 if (sd.region_align_down(old_src_addr) != end_addr) {
2864 // The partial object was copied from more than one source region.
2865 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2866
2867 // Move to the next source region, possibly switching spaces as well. All
2868 // args except end_addr may be modified.
2869 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2870 end_addr);
2871 }
2872 }
2873
2874 do {
2875 HeapWord* const cur_addr = closure.source();
2876 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2877 src_space_top);
2878 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
2879
2880 if (status == ParMarkBitMap::incomplete) {
2881 // The last obj that starts in the source region does not end in the
2882 // region.
2883 assert(closure.source() < end_addr, "sanity");
2884 HeapWord* const obj_beg = closure.source();
2885 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
2886 src_space_top);
2887 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
2888 if (obj_end < range_end) {
2889 // The end was found; the entire object will fit.
2890 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
2891 assert(status != ParMarkBitMap::would_overflow, "sanity");
2892 } else {
2893 // The end was not found; the object will not fit.
2894 assert(range_end < src_space_top, "obj cannot cross space boundary");
2895 status = ParMarkBitMap::would_overflow;
2896 }
2897 }
2898
2899 if (status == ParMarkBitMap::would_overflow) {
2900 // The last object did not fit. Note that interior oop updates were
2901 // deferred, then copy enough of the object to fill the region.
2902 region_ptr->set_deferred_obj_addr(closure.destination());
2903 status = closure.copy_until_full(); // copies from closure.source()
2904
2905 decrement_destination_counts(cm, src_space_id, src_region_idx,
2906 closure.source());
2907 region_ptr->set_completed();
2908 return;
2909 }
2910
2911 if (status == ParMarkBitMap::full) {
2912 decrement_destination_counts(cm, src_space_id, src_region_idx,
2913 closure.source());
2914 region_ptr->set_deferred_obj_addr(NULL);
2915 region_ptr->set_completed();
2916 return;
2917 }
2918
2919 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2920
2921 // Move to the next source region, possibly switching spaces as well. All
2922 // args except end_addr may be modified.
2923 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2924 end_addr);
2925 } while (true);
2926 }
2927
2928 void PSParallelCompact::fill_blocks(size_t region_idx)
2929 {
2930 // Fill in the block table elements for the specified region. Each block
2931 // table element holds the number of live words in the region that are to the
2932 // left of the first object that starts in the block. Thus only blocks in
2933 // which an object starts need to be filled.
2934 //
2935 // The algorithm scans the section of the bitmap that corresponds to the
2936 // region, keeping a running total of the live words. When an object start is
2937 // found, if it's the first to start in the block that contains it, the
2938 // current total is written to the block table element.
2939 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
2940 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
2941 const size_t RegionSize = ParallelCompactData::RegionSize;
2942
2943 ParallelCompactData& sd = summary_data();
2944 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
2945 if (partial_obj_size >= RegionSize) {
2946 return; // No objects start in this region.
2947 }
2948
2949 // Ensure the first loop iteration decides that the block has changed.
2950 size_t cur_block = sd.block_count();
2951
2952 const ParMarkBitMap* const bitmap = mark_bitmap();
2953
2954 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
2955 assert((size_t)1 << Log2BitsPerBlock ==
2956 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
2957
2958 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
2959 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
2960 size_t live_bits = bitmap->words_to_bits(partial_obj_size);
2961 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
2962 while (beg_bit < range_end) {
2963 const size_t new_block = beg_bit >> Log2BitsPerBlock;
2964 if (new_block != cur_block) {
2965 cur_block = new_block;
2966 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
2967 }
2968
2969 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
2970 if (end_bit < range_end - 1) {
2971 live_bits += end_bit - beg_bit + 1;
2972 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
2973 } else {
2974 return;
2975 }
2976 }
2977 }
2978
2979 void
2980 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
2981 const MutableSpace* sp = space(space_id);
2982 if (sp->is_empty()) {
2983 return;
2984 }
2985
2986 ParallelCompactData& sd = PSParallelCompact::summary_data();
2987 ParMarkBitMap* const bitmap = mark_bitmap();
2988 HeapWord* const dp_addr = dense_prefix(space_id);
2989 HeapWord* beg_addr = sp->bottom();
2990 HeapWord* end_addr = sp->top();
2991
2992 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
2993
2994 const size_t beg_region = sd.addr_to_region_idx(beg_addr);
2995 const size_t dp_region = sd.addr_to_region_idx(dp_addr);
2996 if (beg_region < dp_region) {
2997 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
2998 }
2999
3000 // The destination of the first live object that starts in the region is one
3001 // past the end of the partial object entering the region (if any).
3002 HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3003 HeapWord* const new_top = _space_info[space_id].new_top();
3004 assert(new_top >= dest_addr, "bad new_top value");
3005 const size_t words = pointer_delta(new_top, dest_addr);
3006
3007 if (words > 0) {
3008 ObjectStartArray* start_array = _space_info[space_id].start_array();
3009 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3010
3011 ParMarkBitMap::IterationStatus status;
3012 status = bitmap->iterate(&closure, dest_addr, end_addr);
3013 assert(status == ParMarkBitMap::full, "iteration not complete");
3014 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3015 "live objects skipped because closure is full");
3016 }
3017 }
3018
3019 jlong PSParallelCompact::millis_since_last_gc() {
3020 // We need a monotonically non-decreasing time in ms but
3021 // os::javaTimeMillis() does not guarantee monotonicity.
3022 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3023 jlong ret_val = now - _time_of_last_gc;
3024 // XXX See note in genCollectedHeap::millis_since_last_gc().
3025 if (ret_val < 0) {
3026 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);)
3027 return 0;
3028 }
3029 return ret_val;
3030 }
3031
3032 void PSParallelCompact::reset_millis_since_last_gc() {
3033 // We need a monotonically non-decreasing time in ms but
3034 // os::javaTimeMillis() does not guarantee monotonicity.
3035 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3036 }
3037
3038 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3039 {
3040 if (source() != destination()) {
3041 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3042 Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3043 }
3044 update_state(words_remaining());
3045 assert(is_full(), "sanity");
3046 return ParMarkBitMap::full;
3047 }
3048
3049 void MoveAndUpdateClosure::copy_partial_obj()
3050 {
3051 size_t words = words_remaining();
3052
3053 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3054 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3055 if (end_addr < range_end) {
3056 words = bitmap()->obj_size(source(), end_addr);
3057 }
3058
3059 // This test is necessary; if omitted, the pointer updates to a partial object
3060 // that crosses the dense prefix boundary could be overwritten.
3061 if (source() != destination()) {
3062 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3063 Copy::aligned_conjoint_words(source(), destination(), words);
3064 }
3065 update_state(words);
3066 }
3067
3068 void InstanceKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3069 PSParallelCompact::AdjustPointerClosure closure(cm);
3070 oop_oop_iterate_oop_maps<true>(obj, &closure);
3071 }
3072
3073 void InstanceMirrorKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3074 InstanceKlass::oop_pc_update_pointers(obj, cm);
3075
3076 PSParallelCompact::AdjustPointerClosure closure(cm);
3077 oop_oop_iterate_statics<true>(obj, &closure);
3078 }
3079
3080 void InstanceClassLoaderKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3081 InstanceKlass::oop_pc_update_pointers(obj, cm);
3082 }
3083
3084 #ifdef ASSERT
3085 template <class T> static void trace_reference_gc(const char *s, oop obj,
3086 T* referent_addr,
3087 T* next_addr,
3088 T* discovered_addr) {
3089 log_develop_trace(gc, ref)("%s obj " PTR_FORMAT, s, p2i(obj));
3090 log_develop_trace(gc, ref)(" referent_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3091 p2i(referent_addr), referent_addr ? p2i(oopDesc::load_decode_heap_oop(referent_addr)) : NULL);
3092 log_develop_trace(gc, ref)(" next_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3093 p2i(next_addr), next_addr ? p2i(oopDesc::load_decode_heap_oop(next_addr)) : NULL);
3094 log_develop_trace(gc, ref)(" discovered_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3095 p2i(discovered_addr), discovered_addr ? p2i(oopDesc::load_decode_heap_oop(discovered_addr)) : NULL);
3096 }
3097 #endif
3098
3099 template <class T>
3100 static void oop_pc_update_pointers_specialized(oop obj, ParCompactionManager* cm) {
3101 T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj);
3102 PSParallelCompact::adjust_pointer(referent_addr, cm);
3103 T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj);
3104 PSParallelCompact::adjust_pointer(next_addr, cm);
3105 T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj);
3106 PSParallelCompact::adjust_pointer(discovered_addr, cm);
3107 debug_only(trace_reference_gc("InstanceRefKlass::oop_update_ptrs", obj,
3108 referent_addr, next_addr, discovered_addr);)
3109 }
3110
3111 void InstanceRefKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3112 InstanceKlass::oop_pc_update_pointers(obj, cm);
3113
3114 if (UseCompressedOops) {
3115 oop_pc_update_pointers_specialized<narrowOop>(obj, cm);
3116 } else {
3117 oop_pc_update_pointers_specialized<oop>(obj, cm);
3118 }
3119 }
3120
3121 void ObjArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3122 assert(obj->is_objArray(), "obj must be obj array");
3123 PSParallelCompact::AdjustPointerClosure closure(cm);
3124 oop_oop_iterate_elements<true>(objArrayOop(obj), &closure);
3125 }
3126
3127 void TypeArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3128 assert(obj->is_typeArray(),"must be a type array");
3129 }
3130
3131 ParMarkBitMapClosure::IterationStatus
3132 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3133 assert(destination() != NULL, "sanity");
3134 assert(bitmap()->obj_size(addr) == words, "bad size");
3135
3136 _source = addr;
3137 assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) ==
3138 destination(), "wrong destination");
3139
3140 if (words > words_remaining()) {
3141 return ParMarkBitMap::would_overflow;
3142 }
3143
3144 // The start_array must be updated even if the object is not moving.
3145 if (_start_array != NULL) {
3146 _start_array->allocate_block(destination());
3147 }
3148
3149 if (destination() != source()) {
3150 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3151 Copy::aligned_conjoint_words(source(), destination(), words);
3152 }
3153
3154 oop moved_oop = (oop) destination();
3155 compaction_manager()->update_contents(moved_oop);
3156 assert(moved_oop->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop));
3157
3158 update_state(words);
3159 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3160 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3161 }
3162
3163 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3164 ParCompactionManager* cm,
3165 PSParallelCompact::SpaceId space_id) :
3166 ParMarkBitMapClosure(mbm, cm),
3167 _space_id(space_id),
3168 _start_array(PSParallelCompact::start_array(space_id))
3169 {
3170 }
3171
3172 // Updates the references in the object to their new values.
3173 ParMarkBitMapClosure::IterationStatus
3174 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3175 do_addr(addr);
3176 return ParMarkBitMap::incomplete;
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 }