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 (!UseParallelOldGC) {
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 // Initialize static fields in ParCompactionManager.
875 ParCompactionManager::initialize(mark_bitmap());
876 }
877
878 bool PSParallelCompact::initialize() {
879 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
880 MemRegion mr = heap->reserved_region();
881
882 // Was the old gen get allocated successfully?
883 if (!heap->old_gen()->is_allocated()) {
884 return false;
885 }
886
887 initialize_space_info();
888 initialize_dead_wood_limiter();
889
890 if (!_mark_bitmap.initialize(mr)) {
891 vm_shutdown_during_initialization(
892 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
893 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
894 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
895 return false;
896 }
897
898 if (!_summary_data.initialize(mr)) {
899 vm_shutdown_during_initialization(
900 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
901 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
902 _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
903 return false;
904 }
905
906 return true;
907 }
908
909 void PSParallelCompact::initialize_space_info()
910 {
911 memset(&_space_info, 0, sizeof(_space_info));
912
913 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
914 PSYoungGen* young_gen = heap->young_gen();
915
916 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
917 _space_info[eden_space_id].set_space(young_gen->eden_space());
918 _space_info[from_space_id].set_space(young_gen->from_space());
919 _space_info[to_space_id].set_space(young_gen->to_space());
920
921 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
922 }
923
924 void PSParallelCompact::initialize_dead_wood_limiter()
925 {
926 const size_t max = 100;
927 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
928 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
929 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
930 DEBUG_ONLY(_dwl_initialized = true;)
931 _dwl_adjustment = normal_distribution(1.0);
932 }
933
934 void
935 PSParallelCompact::clear_data_covering_space(SpaceId id)
936 {
937 // At this point, top is the value before GC, new_top() is the value that will
938 // be set at the end of GC. The marking bitmap is cleared to top; nothing
939 // should be marked above top. The summary data is cleared to the larger of
940 // top & new_top.
941 MutableSpace* const space = _space_info[id].space();
942 HeapWord* const bot = space->bottom();
943 HeapWord* const top = space->top();
944 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
945
946 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
947 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
948 _mark_bitmap.clear_range(beg_bit, end_bit);
949
950 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
951 const size_t end_region =
952 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
953 _summary_data.clear_range(beg_region, end_region);
954
955 // Clear the data used to 'split' regions.
956 SplitInfo& split_info = _space_info[id].split_info();
957 if (split_info.is_valid()) {
958 split_info.clear();
959 }
960 DEBUG_ONLY(split_info.verify_clear();)
961 }
962
963 void PSParallelCompact::pre_compact()
964 {
965 // Update the from & to space pointers in space_info, since they are swapped
966 // at each young gen gc. Do the update unconditionally (even though a
967 // promotion failure does not swap spaces) because an unknown number of young
968 // collections will have swapped the spaces an unknown number of times.
969 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer);
970 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
971 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
972 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
973
974 DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
975 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
976
977 // Increment the invocation count
978 heap->increment_total_collections(true);
979
980 // We need to track unique mark sweep invocations as well.
981 _total_invocations++;
982
983 heap->print_heap_before_gc();
984 heap->trace_heap_before_gc(&_gc_tracer);
985
986 // Fill in TLABs
987 heap->accumulate_statistics_all_tlabs();
988 heap->ensure_parsability(true); // retire TLABs
989
990 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
991 HandleMark hm; // Discard invalid handles created during verification
992 Universe::verify("Before GC");
993 }
994
995 // Verify object start arrays
996 if (VerifyObjectStartArray &&
997 VerifyBeforeGC) {
998 heap->old_gen()->verify_object_start_array();
999 }
1000
1001 DEBUG_ONLY(mark_bitmap()->verify_clear();)
1002 DEBUG_ONLY(summary_data().verify_clear();)
1003
1004 // Have worker threads release resources the next time they run a task.
1005 gc_task_manager()->release_all_resources();
1006
1007 ParCompactionManager::reset_all_bitmap_query_caches();
1008 }
1009
1010 void PSParallelCompact::post_compact()
1011 {
1012 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer);
1013
1014 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1015 // Clear the marking bitmap, summary data and split info.
1016 clear_data_covering_space(SpaceId(id));
1017 // Update top(). Must be done after clearing the bitmap and summary data.
1018 _space_info[id].publish_new_top();
1019 }
1020
1021 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1022 MutableSpace* const from_space = _space_info[from_space_id].space();
1023 MutableSpace* const to_space = _space_info[to_space_id].space();
1024
1025 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1026 bool eden_empty = eden_space->is_empty();
1027 if (!eden_empty) {
1028 eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1029 heap->young_gen(), heap->old_gen());
1030 }
1031
1032 // Update heap occupancy information which is used as input to the soft ref
1033 // clearing policy at the next gc.
1034 Universe::update_heap_info_at_gc();
1035
1036 bool young_gen_empty = eden_empty && from_space->is_empty() &&
1037 to_space->is_empty();
1038
1039 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set());
1040 MemRegion old_mr = heap->old_gen()->reserved();
1041 if (young_gen_empty) {
1042 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
1043 } else {
1044 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1045 }
1046
1047 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1048 ClassLoaderDataGraph::purge();
1049 MetaspaceAux::verify_metrics();
1050
1051 CodeCache::gc_epilogue();
1052 JvmtiExport::gc_epilogue();
1053
1054 #if defined(COMPILER2) || INCLUDE_JVMCI
1055 DerivedPointerTable::update_pointers();
1056 #endif
1057
1058 ref_processor()->enqueue_discovered_references(NULL);
1059
1060 if (ZapUnusedHeapArea) {
1061 heap->gen_mangle_unused_area();
1062 }
1063
1064 // Update time of last GC
1065 reset_millis_since_last_gc();
1066 }
1067
1068 HeapWord*
1069 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1070 bool maximum_compaction)
1071 {
1072 const size_t region_size = ParallelCompactData::RegionSize;
1073 const ParallelCompactData& sd = summary_data();
1074
1075 const MutableSpace* const space = _space_info[id].space();
1076 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1077 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1078 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1079
1080 // Skip full regions at the beginning of the space--they are necessarily part
1081 // of the dense prefix.
1082 size_t full_count = 0;
1083 const RegionData* cp;
1084 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1085 ++full_count;
1086 }
1087
1088 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1089 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1090 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1091 if (maximum_compaction || cp == end_cp || interval_ended) {
1092 _maximum_compaction_gc_num = total_invocations();
1093 return sd.region_to_addr(cp);
1094 }
1095
1096 HeapWord* const new_top = _space_info[id].new_top();
1097 const size_t space_live = pointer_delta(new_top, space->bottom());
1098 const size_t space_used = space->used_in_words();
1099 const size_t space_capacity = space->capacity_in_words();
1100
1101 const double cur_density = double(space_live) / space_capacity;
1102 const double deadwood_density =
1103 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1104 const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1105
1106 if (TraceParallelOldGCDensePrefix) {
1107 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1108 cur_density, deadwood_density, deadwood_goal);
1109 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1110 "space_cap=" SIZE_FORMAT,
1111 space_live, space_used,
1112 space_capacity);
1113 }
1114
1115 // XXX - Use binary search?
1116 HeapWord* dense_prefix = sd.region_to_addr(cp);
1117 const RegionData* full_cp = cp;
1118 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1119 while (cp < end_cp) {
1120 HeapWord* region_destination = cp->destination();
1121 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1122 if (TraceParallelOldGCDensePrefix && Verbose) {
1123 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1124 "dp=" PTR_FORMAT " " "cdw=" SIZE_FORMAT_W(8),
1125 sd.region(cp), p2i(region_destination),
1126 p2i(dense_prefix), cur_deadwood);
1127 }
1128
1129 if (cur_deadwood >= deadwood_goal) {
1130 // Found the region that has the correct amount of deadwood to the left.
1131 // This typically occurs after crossing a fairly sparse set of regions, so
1132 // iterate backwards over those sparse regions, looking for the region
1133 // that has the lowest density of live objects 'to the right.'
1134 size_t space_to_left = sd.region(cp) * region_size;
1135 size_t live_to_left = space_to_left - cur_deadwood;
1136 size_t space_to_right = space_capacity - space_to_left;
1137 size_t live_to_right = space_live - live_to_left;
1138 double density_to_right = double(live_to_right) / space_to_right;
1139 while (cp > full_cp) {
1140 --cp;
1141 const size_t prev_region_live_to_right = live_to_right -
1142 cp->data_size();
1143 const size_t prev_region_space_to_right = space_to_right + region_size;
1144 double prev_region_density_to_right =
1145 double(prev_region_live_to_right) / prev_region_space_to_right;
1146 if (density_to_right <= prev_region_density_to_right) {
1147 return dense_prefix;
1148 }
1149 if (TraceParallelOldGCDensePrefix && Verbose) {
1150 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1151 "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1152 prev_region_density_to_right);
1153 }
1154 dense_prefix -= region_size;
1155 live_to_right = prev_region_live_to_right;
1156 space_to_right = prev_region_space_to_right;
1157 density_to_right = prev_region_density_to_right;
1158 }
1159 return dense_prefix;
1160 }
1161
1162 dense_prefix += region_size;
1163 ++cp;
1164 }
1165
1166 return dense_prefix;
1167 }
1168
1169 #ifndef PRODUCT
1170 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1171 const SpaceId id,
1172 const bool maximum_compaction,
1173 HeapWord* const addr)
1174 {
1175 const size_t region_idx = summary_data().addr_to_region_idx(addr);
1176 RegionData* const cp = summary_data().region(region_idx);
1177 const MutableSpace* const space = _space_info[id].space();
1178 HeapWord* const new_top = _space_info[id].new_top();
1179
1180 const size_t space_live = pointer_delta(new_top, space->bottom());
1181 const size_t dead_to_left = pointer_delta(addr, cp->destination());
1182 const size_t space_cap = space->capacity_in_words();
1183 const double dead_to_left_pct = double(dead_to_left) / space_cap;
1184 const size_t live_to_right = new_top - cp->destination();
1185 const size_t dead_to_right = space->top() - addr - live_to_right;
1186
1187 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1188 "spl=" SIZE_FORMAT " "
1189 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1190 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1191 " ratio=%10.8f",
1192 algorithm, p2i(addr), region_idx,
1193 space_live,
1194 dead_to_left, dead_to_left_pct,
1195 dead_to_right, live_to_right,
1196 double(dead_to_right) / live_to_right);
1197 }
1198 #endif // #ifndef PRODUCT
1199
1200 // Return a fraction indicating how much of the generation can be treated as
1201 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution
1202 // based on the density of live objects in the generation to determine a limit,
1203 // which is then adjusted so the return value is min_percent when the density is
1204 // 1.
1205 //
1206 // The following table shows some return values for a different values of the
1207 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1208 // min_percent is 1.
1209 //
1210 // fraction allowed as dead wood
1211 // -----------------------------------------------------------------
1212 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1213 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1214 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1215 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1216 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1217 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1218 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1219 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1220 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1221 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1222 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1223 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1224 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1225 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1226 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1227 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1228 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1229 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1230 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1231 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1232 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1233 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1234 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1235
1236 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1237 {
1238 assert(_dwl_initialized, "uninitialized");
1239
1240 // The raw limit is the value of the normal distribution at x = density.
1241 const double raw_limit = normal_distribution(density);
1242
1243 // Adjust the raw limit so it becomes the minimum when the density is 1.
1244 //
1245 // First subtract the adjustment value (which is simply the precomputed value
1246 // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1247 // Then add the minimum value, so the minimum is returned when the density is
1248 // 1. Finally, prevent negative values, which occur when the mean is not 0.5.
1249 const double min = double(min_percent) / 100.0;
1250 const double limit = raw_limit - _dwl_adjustment + min;
1251 return MAX2(limit, 0.0);
1252 }
1253
1254 ParallelCompactData::RegionData*
1255 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1256 const RegionData* end)
1257 {
1258 const size_t region_size = ParallelCompactData::RegionSize;
1259 ParallelCompactData& sd = summary_data();
1260 size_t left = sd.region(beg);
1261 size_t right = end > beg ? sd.region(end) - 1 : left;
1262
1263 // Binary search.
1264 while (left < right) {
1265 // Equivalent to (left + right) / 2, but does not overflow.
1266 const size_t middle = left + (right - left) / 2;
1267 RegionData* const middle_ptr = sd.region(middle);
1268 HeapWord* const dest = middle_ptr->destination();
1269 HeapWord* const addr = sd.region_to_addr(middle);
1270 assert(dest != NULL, "sanity");
1271 assert(dest <= addr, "must move left");
1272
1273 if (middle > left && dest < addr) {
1274 right = middle - 1;
1275 } else if (middle < right && middle_ptr->data_size() == region_size) {
1276 left = middle + 1;
1277 } else {
1278 return middle_ptr;
1279 }
1280 }
1281 return sd.region(left);
1282 }
1283
1284 ParallelCompactData::RegionData*
1285 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1286 const RegionData* end,
1287 size_t dead_words)
1288 {
1289 ParallelCompactData& sd = summary_data();
1290 size_t left = sd.region(beg);
1291 size_t right = end > beg ? sd.region(end) - 1 : left;
1292
1293 // Binary search.
1294 while (left < right) {
1295 // Equivalent to (left + right) / 2, but does not overflow.
1296 const size_t middle = left + (right - left) / 2;
1297 RegionData* const middle_ptr = sd.region(middle);
1298 HeapWord* const dest = middle_ptr->destination();
1299 HeapWord* const addr = sd.region_to_addr(middle);
1300 assert(dest != NULL, "sanity");
1301 assert(dest <= addr, "must move left");
1302
1303 const size_t dead_to_left = pointer_delta(addr, dest);
1304 if (middle > left && dead_to_left > dead_words) {
1305 right = middle - 1;
1306 } else if (middle < right && dead_to_left < dead_words) {
1307 left = middle + 1;
1308 } else {
1309 return middle_ptr;
1310 }
1311 }
1312 return sd.region(left);
1313 }
1314
1315 // The result is valid during the summary phase, after the initial summarization
1316 // of each space into itself, and before final summarization.
1317 inline double
1318 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1319 HeapWord* const bottom,
1320 HeapWord* const top,
1321 HeapWord* const new_top)
1322 {
1323 ParallelCompactData& sd = summary_data();
1324
1325 assert(cp != NULL, "sanity");
1326 assert(bottom != NULL, "sanity");
1327 assert(top != NULL, "sanity");
1328 assert(new_top != NULL, "sanity");
1329 assert(top >= new_top, "summary data problem?");
1330 assert(new_top > bottom, "space is empty; should not be here");
1331 assert(new_top >= cp->destination(), "sanity");
1332 assert(top >= sd.region_to_addr(cp), "sanity");
1333
1334 HeapWord* const destination = cp->destination();
1335 const size_t dense_prefix_live = pointer_delta(destination, bottom);
1336 const size_t compacted_region_live = pointer_delta(new_top, destination);
1337 const size_t compacted_region_used = pointer_delta(top,
1338 sd.region_to_addr(cp));
1339 const size_t reclaimable = compacted_region_used - compacted_region_live;
1340
1341 const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1342 return double(reclaimable) / divisor;
1343 }
1344
1345 // Return the address of the end of the dense prefix, a.k.a. the start of the
1346 // compacted region. The address is always on a region boundary.
1347 //
1348 // Completely full regions at the left are skipped, since no compaction can
1349 // occur in those regions. Then the maximum amount of dead wood to allow is
1350 // computed, based on the density (amount live / capacity) of the generation;
1351 // the region with approximately that amount of dead space to the left is
1352 // identified as the limit region. Regions between the last completely full
1353 // region and the limit region are scanned and the one that has the best
1354 // (maximum) reclaimed_ratio() is selected.
1355 HeapWord*
1356 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1357 bool maximum_compaction)
1358 {
1359 const size_t region_size = ParallelCompactData::RegionSize;
1360 const ParallelCompactData& sd = summary_data();
1361
1362 const MutableSpace* const space = _space_info[id].space();
1363 HeapWord* const top = space->top();
1364 HeapWord* const top_aligned_up = sd.region_align_up(top);
1365 HeapWord* const new_top = _space_info[id].new_top();
1366 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1367 HeapWord* const bottom = space->bottom();
1368 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1369 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1370 const RegionData* const new_top_cp =
1371 sd.addr_to_region_ptr(new_top_aligned_up);
1372
1373 // Skip full regions at the beginning of the space--they are necessarily part
1374 // of the dense prefix.
1375 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1376 assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1377 space->is_empty(), "no dead space allowed to the left");
1378 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1379 "region must have dead space");
1380
1381 // The gc number is saved whenever a maximum compaction is done, and used to
1382 // determine when the maximum compaction interval has expired. This avoids
1383 // successive max compactions for different reasons.
1384 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1385 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1386 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1387 total_invocations() == HeapFirstMaximumCompactionCount;
1388 if (maximum_compaction || full_cp == top_cp || interval_ended) {
1389 _maximum_compaction_gc_num = total_invocations();
1390 return sd.region_to_addr(full_cp);
1391 }
1392
1393 const size_t space_live = pointer_delta(new_top, bottom);
1394 const size_t space_used = space->used_in_words();
1395 const size_t space_capacity = space->capacity_in_words();
1396
1397 const double density = double(space_live) / double(space_capacity);
1398 const size_t min_percent_free = MarkSweepDeadRatio;
1399 const double limiter = dead_wood_limiter(density, min_percent_free);
1400 const size_t dead_wood_max = space_used - space_live;
1401 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1402 dead_wood_max);
1403
1404 if (TraceParallelOldGCDensePrefix) {
1405 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1406 "space_cap=" SIZE_FORMAT,
1407 space_live, space_used,
1408 space_capacity);
1409 tty->print_cr("dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f "
1410 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1411 density, min_percent_free, limiter,
1412 dead_wood_max, dead_wood_limit);
1413 }
1414
1415 // Locate the region with the desired amount of dead space to the left.
1416 const RegionData* const limit_cp =
1417 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1418
1419 // Scan from the first region with dead space to the limit region and find the
1420 // one with the best (largest) reclaimed ratio.
1421 double best_ratio = 0.0;
1422 const RegionData* best_cp = full_cp;
1423 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1424 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1425 if (tmp_ratio > best_ratio) {
1426 best_cp = cp;
1427 best_ratio = tmp_ratio;
1428 }
1429 }
1430
1431 return sd.region_to_addr(best_cp);
1432 }
1433
1434 void PSParallelCompact::summarize_spaces_quick()
1435 {
1436 for (unsigned int i = 0; i < last_space_id; ++i) {
1437 const MutableSpace* space = _space_info[i].space();
1438 HeapWord** nta = _space_info[i].new_top_addr();
1439 bool result = _summary_data.summarize(_space_info[i].split_info(),
1440 space->bottom(), space->top(), NULL,
1441 space->bottom(), space->end(), nta);
1442 assert(result, "space must fit into itself");
1443 _space_info[i].set_dense_prefix(space->bottom());
1444 }
1445 }
1446
1447 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1448 {
1449 HeapWord* const dense_prefix_end = dense_prefix(id);
1450 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1451 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1452 if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1453 // Only enough dead space is filled so that any remaining dead space to the
1454 // left is larger than the minimum filler object. (The remainder is filled
1455 // during the copy/update phase.)
1456 //
1457 // The size of the dead space to the right of the boundary is not a
1458 // concern, since compaction will be able to use whatever space is
1459 // available.
1460 //
1461 // Here '||' is the boundary, 'x' represents a don't care bit and a box
1462 // surrounds the space to be filled with an object.
1463 //
1464 // In the 32-bit VM, each bit represents two 32-bit words:
1465 // +---+
1466 // a) beg_bits: ... x x x | 0 | || 0 x x ...
1467 // end_bits: ... x x x | 0 | || 0 x x ...
1468 // +---+
1469 //
1470 // In the 64-bit VM, each bit represents one 64-bit word:
1471 // +------------+
1472 // b) beg_bits: ... x x x | 0 || 0 | x x ...
1473 // end_bits: ... x x 1 | 0 || 0 | x x ...
1474 // +------------+
1475 // +-------+
1476 // c) beg_bits: ... x x | 0 0 | || 0 x x ...
1477 // end_bits: ... x 1 | 0 0 | || 0 x x ...
1478 // +-------+
1479 // +-----------+
1480 // d) beg_bits: ... x | 0 0 0 | || 0 x x ...
1481 // end_bits: ... 1 | 0 0 0 | || 0 x x ...
1482 // +-----------+
1483 // +-------+
1484 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ...
1485 // end_bits: ... 0 0 | 0 0 | || 0 x x ...
1486 // +-------+
1487
1488 // Initially assume case a, c or e will apply.
1489 size_t obj_len = CollectedHeap::min_fill_size();
1490 HeapWord* obj_beg = dense_prefix_end - obj_len;
1491
1492 #ifdef _LP64
1493 if (MinObjAlignment > 1) { // object alignment > heap word size
1494 // Cases a, c or e.
1495 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1496 // Case b above.
1497 obj_beg = dense_prefix_end - 1;
1498 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1499 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1500 // Case d above.
1501 obj_beg = dense_prefix_end - 3;
1502 obj_len = 3;
1503 }
1504 #endif // #ifdef _LP64
1505
1506 CollectedHeap::fill_with_object(obj_beg, obj_len);
1507 _mark_bitmap.mark_obj(obj_beg, obj_len);
1508 _summary_data.add_obj(obj_beg, obj_len);
1509 assert(start_array(id) != NULL, "sanity");
1510 start_array(id)->allocate_block(obj_beg);
1511 }
1512 }
1513
1514 void
1515 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1516 {
1517 assert(id < last_space_id, "id out of range");
1518 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(),
1519 "should have been reset in summarize_spaces_quick()");
1520
1521 const MutableSpace* space = _space_info[id].space();
1522 if (_space_info[id].new_top() != space->bottom()) {
1523 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1524 _space_info[id].set_dense_prefix(dense_prefix_end);
1525
1526 #ifndef PRODUCT
1527 if (TraceParallelOldGCDensePrefix) {
1528 print_dense_prefix_stats("ratio", id, maximum_compaction,
1529 dense_prefix_end);
1530 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1531 print_dense_prefix_stats("density", id, maximum_compaction, addr);
1532 }
1533 #endif // #ifndef PRODUCT
1534
1535 // Recompute the summary data, taking into account the dense prefix. If
1536 // every last byte will be reclaimed, then the existing summary data which
1537 // compacts everything can be left in place.
1538 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1539 // If dead space crosses the dense prefix boundary, it is (at least
1540 // partially) filled with a dummy object, marked live and added to the
1541 // summary data. This simplifies the copy/update phase and must be done
1542 // before the final locations of objects are determined, to prevent
1543 // leaving a fragment of dead space that is too small to fill.
1544 fill_dense_prefix_end(id);
1545
1546 // Compute the destination of each Region, and thus each object.
1547 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1548 _summary_data.summarize(_space_info[id].split_info(),
1549 dense_prefix_end, space->top(), NULL,
1550 dense_prefix_end, space->end(),
1551 _space_info[id].new_top_addr());
1552 }
1553 }
1554
1555 if (log_develop_is_enabled(Trace, gc, compaction)) {
1556 const size_t region_size = ParallelCompactData::RegionSize;
1557 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1558 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1559 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1560 HeapWord* const new_top = _space_info[id].new_top();
1561 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1562 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1563 log_develop_trace(gc, compaction)(
1564 "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1565 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1566 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1567 id, space->capacity_in_words(), p2i(dense_prefix_end),
1568 dp_region, dp_words / region_size,
1569 cr_words / region_size, p2i(new_top));
1570 }
1571 }
1572
1573 #ifndef PRODUCT
1574 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1575 HeapWord* dst_beg, HeapWord* dst_end,
1576 SpaceId src_space_id,
1577 HeapWord* src_beg, HeapWord* src_end)
1578 {
1579 log_develop_trace(gc, compaction)(
1580 "Summarizing %d [%s] into %d [%s]: "
1581 "src=" PTR_FORMAT "-" PTR_FORMAT " "
1582 SIZE_FORMAT "-" SIZE_FORMAT " "
1583 "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1584 SIZE_FORMAT "-" SIZE_FORMAT,
1585 src_space_id, space_names[src_space_id],
1586 dst_space_id, space_names[dst_space_id],
1587 p2i(src_beg), p2i(src_end),
1588 _summary_data.addr_to_region_idx(src_beg),
1589 _summary_data.addr_to_region_idx(src_end),
1590 p2i(dst_beg), p2i(dst_end),
1591 _summary_data.addr_to_region_idx(dst_beg),
1592 _summary_data.addr_to_region_idx(dst_end));
1593 }
1594 #endif // #ifndef PRODUCT
1595
1596 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1597 bool maximum_compaction)
1598 {
1599 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer);
1600
1601 #ifdef ASSERT
1602 if (TraceParallelOldGCMarkingPhase) {
1603 tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1604 "add_obj_bytes=" SIZE_FORMAT,
1605 add_obj_count, add_obj_size * HeapWordSize);
1606 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1607 "mark_bitmap_bytes=" SIZE_FORMAT,
1608 mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1609 }
1610 #endif // #ifdef ASSERT
1611
1612 // Quick summarization of each space into itself, to see how much is live.
1613 summarize_spaces_quick();
1614
1615 log_develop_trace(gc, compaction)("summary phase: after summarizing each space to self");
1616 NOT_PRODUCT(print_region_ranges());
1617 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1618
1619 // The amount of live data that will end up in old space (assuming it fits).
1620 size_t old_space_total_live = 0;
1621 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1622 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1623 _space_info[id].space()->bottom());
1624 }
1625
1626 MutableSpace* const old_space = _space_info[old_space_id].space();
1627 const size_t old_capacity = old_space->capacity_in_words();
1628 if (old_space_total_live > old_capacity) {
1629 // XXX - should also try to expand
1630 maximum_compaction = true;
1631 }
1632
1633 // Old generations.
1634 summarize_space(old_space_id, maximum_compaction);
1635
1636 // Summarize the remaining spaces in the young gen. The initial target space
1637 // is the old gen. If a space does not fit entirely into the target, then the
1638 // remainder is compacted into the space itself and that space becomes the new
1639 // target.
1640 SpaceId dst_space_id = old_space_id;
1641 HeapWord* dst_space_end = old_space->end();
1642 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1643 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1644 const MutableSpace* space = _space_info[id].space();
1645 const size_t live = pointer_delta(_space_info[id].new_top(),
1646 space->bottom());
1647 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1648
1649 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1650 SpaceId(id), space->bottom(), space->top());)
1651 if (live > 0 && live <= available) {
1652 // All the live data will fit.
1653 bool done = _summary_data.summarize(_space_info[id].split_info(),
1654 space->bottom(), space->top(),
1655 NULL,
1656 *new_top_addr, dst_space_end,
1657 new_top_addr);
1658 assert(done, "space must fit into old gen");
1659
1660 // Reset the new_top value for the space.
1661 _space_info[id].set_new_top(space->bottom());
1662 } else if (live > 0) {
1663 // Attempt to fit part of the source space into the target space.
1664 HeapWord* next_src_addr = NULL;
1665 bool done = _summary_data.summarize(_space_info[id].split_info(),
1666 space->bottom(), space->top(),
1667 &next_src_addr,
1668 *new_top_addr, dst_space_end,
1669 new_top_addr);
1670 assert(!done, "space should not fit into old gen");
1671 assert(next_src_addr != NULL, "sanity");
1672
1673 // The source space becomes the new target, so the remainder is compacted
1674 // within the space itself.
1675 dst_space_id = SpaceId(id);
1676 dst_space_end = space->end();
1677 new_top_addr = _space_info[id].new_top_addr();
1678 NOT_PRODUCT(summary_phase_msg(dst_space_id,
1679 space->bottom(), dst_space_end,
1680 SpaceId(id), next_src_addr, space->top());)
1681 done = _summary_data.summarize(_space_info[id].split_info(),
1682 next_src_addr, space->top(),
1683 NULL,
1684 space->bottom(), dst_space_end,
1685 new_top_addr);
1686 assert(done, "space must fit when compacted into itself");
1687 assert(*new_top_addr <= space->top(), "usage should not grow");
1688 }
1689 }
1690
1691 log_develop_trace(gc, compaction)("Summary_phase: after final summarization");
1692 NOT_PRODUCT(print_region_ranges());
1693 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1694 }
1695
1696 // This method should contain all heap-specific policy for invoking a full
1697 // collection. invoke_no_policy() will only attempt to compact the heap; it
1698 // will do nothing further. If we need to bail out for policy reasons, scavenge
1699 // before full gc, or any other specialized behavior, it needs to be added here.
1700 //
1701 // Note that this method should only be called from the vm_thread while at a
1702 // safepoint.
1703 //
1704 // Note that the all_soft_refs_clear flag in the collector policy
1705 // may be true because this method can be called without intervening
1706 // activity. For example when the heap space is tight and full measure
1707 // are being taken to free space.
1708 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1709 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1710 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1711 "should be in vm thread");
1712
1713 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1714 GCCause::Cause gc_cause = heap->gc_cause();
1715 assert(!heap->is_gc_active(), "not reentrant");
1716
1717 PSAdaptiveSizePolicy* policy = heap->size_policy();
1718 IsGCActiveMark mark;
1719
1720 if (ScavengeBeforeFullGC) {
1721 PSScavenge::invoke_no_policy();
1722 }
1723
1724 const bool clear_all_soft_refs =
1725 heap->collector_policy()->should_clear_all_soft_refs();
1726
1727 PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1728 maximum_heap_compaction);
1729 }
1730
1731 // This method contains no policy. You should probably
1732 // be calling invoke() instead.
1733 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1734 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1735 assert(ref_processor() != NULL, "Sanity");
1736
1737 if (GCLocker::check_active_before_gc()) {
1738 return false;
1739 }
1740
1741 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1742
1743 GCIdMark gc_id_mark;
1744 _gc_timer.register_gc_start();
1745 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
1746
1747 TimeStamp marking_start;
1748 TimeStamp compaction_start;
1749 TimeStamp collection_exit;
1750
1751 GCCause::Cause gc_cause = heap->gc_cause();
1752 PSYoungGen* young_gen = heap->young_gen();
1753 PSOldGen* old_gen = heap->old_gen();
1754 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1755
1756 // The scope of casr should end after code that can change
1757 // CollectorPolicy::_should_clear_all_soft_refs.
1758 ClearedAllSoftRefs casr(maximum_heap_compaction,
1759 heap->collector_policy());
1760
1761 if (ZapUnusedHeapArea) {
1762 // Save information needed to minimize mangling
1763 heap->record_gen_tops_before_GC();
1764 }
1765
1766 // Make sure data structures are sane, make the heap parsable, and do other
1767 // miscellaneous bookkeeping.
1768 pre_compact();
1769
1770 PreGCValues pre_gc_values(heap);
1771
1772 // Get the compaction manager reserved for the VM thread.
1773 ParCompactionManager* const vmthread_cm =
1774 ParCompactionManager::manager_array(gc_task_manager()->workers());
1775
1776 {
1777 ResourceMark rm;
1778 HandleMark hm;
1779
1780 // Set the number of GC threads to be used in this collection
1781 gc_task_manager()->set_active_gang();
1782 gc_task_manager()->task_idle_workers();
1783
1784 GCTraceCPUTime tcpu;
1785 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause, true);
1786
1787 heap->pre_full_gc_dump(&_gc_timer);
1788
1789 TraceCollectorStats tcs(counters());
1790 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
1791
1792 if (TraceOldGenTime) accumulated_time()->start();
1793
1794 // Let the size policy know we're starting
1795 size_policy->major_collection_begin();
1796
1797 CodeCache::gc_prologue();
1798
1799 #if defined(COMPILER2) || INCLUDE_JVMCI
1800 DerivedPointerTable::clear();
1801 #endif
1802
1803 ref_processor()->enable_discovery();
1804 ref_processor()->setup_policy(maximum_heap_compaction);
1805
1806 bool marked_for_unloading = false;
1807
1808 marking_start.update();
1809 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer);
1810
1811 bool max_on_system_gc = UseMaximumCompactionOnSystemGC
1812 && GCCause::is_user_requested_gc(gc_cause);
1813 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
1814
1815 #if defined(COMPILER2) || INCLUDE_JVMCI
1816 assert(DerivedPointerTable::is_active(), "Sanity");
1817 DerivedPointerTable::set_active(false);
1818 #endif
1819
1820 // adjust_roots() updates Universe::_intArrayKlassObj which is
1821 // needed by the compaction for filling holes in the dense prefix.
1822 adjust_roots(vmthread_cm);
1823
1824 compaction_start.update();
1825 compact();
1826
1827 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
1828 // done before resizing.
1829 post_compact();
1830
1831 // Let the size policy know we're done
1832 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
1833
1834 if (UseAdaptiveSizePolicy) {
1835 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
1836 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
1837 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
1838
1839 // Don't check if the size_policy is ready here. Let
1840 // the size_policy check that internally.
1841 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
1842 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
1843 // Swap the survivor spaces if from_space is empty. The
1844 // resize_young_gen() called below is normally used after
1845 // a successful young GC and swapping of survivor spaces;
1846 // otherwise, it will fail to resize the young gen with
1847 // the current implementation.
1848 if (young_gen->from_space()->is_empty()) {
1849 young_gen->from_space()->clear(SpaceDecorator::Mangle);
1850 young_gen->swap_spaces();
1851 }
1852
1853 // Calculate optimal free space amounts
1854 assert(young_gen->max_size() >
1855 young_gen->from_space()->capacity_in_bytes() +
1856 young_gen->to_space()->capacity_in_bytes(),
1857 "Sizes of space in young gen are out-of-bounds");
1858
1859 size_t young_live = young_gen->used_in_bytes();
1860 size_t eden_live = young_gen->eden_space()->used_in_bytes();
1861 size_t old_live = old_gen->used_in_bytes();
1862 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
1863 size_t max_old_gen_size = old_gen->max_gen_size();
1864 size_t max_eden_size = young_gen->max_size() -
1865 young_gen->from_space()->capacity_in_bytes() -
1866 young_gen->to_space()->capacity_in_bytes();
1867
1868 // Used for diagnostics
1869 size_policy->clear_generation_free_space_flags();
1870
1871 size_policy->compute_generations_free_space(young_live,
1872 eden_live,
1873 old_live,
1874 cur_eden,
1875 max_old_gen_size,
1876 max_eden_size,
1877 true /* full gc*/);
1878
1879 size_policy->check_gc_overhead_limit(young_live,
1880 eden_live,
1881 max_old_gen_size,
1882 max_eden_size,
1883 true /* full gc*/,
1884 gc_cause,
1885 heap->collector_policy());
1886
1887 size_policy->decay_supplemental_growth(true /* full gc*/);
1888
1889 heap->resize_old_gen(
1890 size_policy->calculated_old_free_size_in_bytes());
1891
1892 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
1893 size_policy->calculated_survivor_size_in_bytes());
1894 }
1895
1896 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
1897 }
1898
1899 if (UsePerfData) {
1900 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
1901 counters->update_counters();
1902 counters->update_old_capacity(old_gen->capacity_in_bytes());
1903 counters->update_young_capacity(young_gen->capacity_in_bytes());
1904 }
1905
1906 heap->resize_all_tlabs();
1907
1908 // Resize the metaspace capacity after a collection
1909 MetaspaceGC::compute_new_size();
1910
1911 if (TraceOldGenTime) {
1912 accumulated_time()->stop();
1913 }
1914
1915 young_gen->print_used_change(pre_gc_values.young_gen_used());
1916 old_gen->print_used_change(pre_gc_values.old_gen_used());
1917 MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used());
1918
1919 // Track memory usage and detect low memory
1920 MemoryService::track_memory_usage();
1921 heap->update_counters();
1922 gc_task_manager()->release_idle_workers();
1923
1924 heap->post_full_gc_dump(&_gc_timer);
1925 }
1926
1927 #ifdef ASSERT
1928 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
1929 ParCompactionManager* const cm =
1930 ParCompactionManager::manager_array(int(i));
1931 assert(cm->marking_stack()->is_empty(), "should be empty");
1932 assert(cm->region_stack()->is_empty(), "Region stack " SIZE_FORMAT " is not empty", i);
1933 }
1934 #endif // ASSERT
1935
1936 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1937 HandleMark hm; // Discard invalid handles created during verification
1938 Universe::verify("After GC");
1939 }
1940
1941 // Re-verify object start arrays
1942 if (VerifyObjectStartArray &&
1943 VerifyAfterGC) {
1944 old_gen->verify_object_start_array();
1945 }
1946
1947 if (ZapUnusedHeapArea) {
1948 old_gen->object_space()->check_mangled_unused_area_complete();
1949 }
1950
1951 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1952
1953 collection_exit.update();
1954
1955 heap->print_heap_after_gc();
1956 heap->trace_heap_after_gc(&_gc_tracer);
1957
1958 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT,
1959 marking_start.ticks(), compaction_start.ticks(),
1960 collection_exit.ticks());
1961 gc_task_manager()->print_task_time_stamps();
1962
1963 #ifdef TRACESPINNING
1964 ParallelTaskTerminator::print_termination_counts();
1965 #endif
1966
1967 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
1968
1969 _gc_timer.register_gc_end();
1970
1971 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
1972 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
1973
1974 return true;
1975 }
1976
1977 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
1978 PSYoungGen* young_gen,
1979 PSOldGen* old_gen) {
1980 MutableSpace* const eden_space = young_gen->eden_space();
1981 assert(!eden_space->is_empty(), "eden must be non-empty");
1982 assert(young_gen->virtual_space()->alignment() ==
1983 old_gen->virtual_space()->alignment(), "alignments do not match");
1984
1985 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
1986 return false;
1987 }
1988
1989 // Both generations must be completely committed.
1990 if (young_gen->virtual_space()->uncommitted_size() != 0) {
1991 return false;
1992 }
1993 if (old_gen->virtual_space()->uncommitted_size() != 0) {
1994 return false;
1995 }
1996
1997 // Figure out how much to take from eden. Include the average amount promoted
1998 // in the total; otherwise the next young gen GC will simply bail out to a
1999 // full GC.
2000 const size_t alignment = old_gen->virtual_space()->alignment();
2001 const size_t eden_used = eden_space->used_in_bytes();
2002 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
2003 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
2004 const size_t eden_capacity = eden_space->capacity_in_bytes();
2005
2006 if (absorb_size >= eden_capacity) {
2007 return false; // Must leave some space in eden.
2008 }
2009
2010 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2011 if (new_young_size < young_gen->min_gen_size()) {
2012 return false; // Respect young gen minimum size.
2013 }
2014
2015 log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K: "
2016 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2017 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2018 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2019 absorb_size / K,
2020 eden_capacity / K, (eden_capacity - absorb_size) / K,
2021 young_gen->from_space()->used_in_bytes() / K,
2022 young_gen->to_space()->used_in_bytes() / K,
2023 young_gen->capacity_in_bytes() / K, new_young_size / K);
2024
2025 // Fill the unused part of the old gen.
2026 MutableSpace* const old_space = old_gen->object_space();
2027 HeapWord* const unused_start = old_space->top();
2028 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2029
2030 if (unused_words > 0) {
2031 if (unused_words < CollectedHeap::min_fill_size()) {
2032 return false; // If the old gen cannot be filled, must give up.
2033 }
2034 CollectedHeap::fill_with_objects(unused_start, unused_words);
2035 }
2036
2037 // Take the live data from eden and set both top and end in the old gen to
2038 // eden top. (Need to set end because reset_after_change() mangles the region
2039 // from end to virtual_space->high() in debug builds).
2040 HeapWord* const new_top = eden_space->top();
2041 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2042 absorb_size);
2043 young_gen->reset_after_change();
2044 old_space->set_top(new_top);
2045 old_space->set_end(new_top);
2046 old_gen->reset_after_change();
2047
2048 // Update the object start array for the filler object and the data from eden.
2049 ObjectStartArray* const start_array = old_gen->start_array();
2050 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2051 start_array->allocate_block(p);
2052 }
2053
2054 // Could update the promoted average here, but it is not typically updated at
2055 // full GCs and the value to use is unclear. Something like
2056 //
2057 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2058
2059 size_policy->set_bytes_absorbed_from_eden(absorb_size);
2060 return true;
2061 }
2062
2063 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2064 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2065 "shouldn't return NULL");
2066 return ParallelScavengeHeap::gc_task_manager();
2067 }
2068
2069 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2070 bool maximum_heap_compaction,
2071 ParallelOldTracer *gc_tracer) {
2072 // Recursively traverse all live objects and mark them
2073 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer);
2074
2075 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2076 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2077 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2078 TaskQueueSetSuper* qset = ParCompactionManager::stack_array();
2079 ParallelTaskTerminator terminator(active_gc_threads, qset);
2080
2081 ParCompactionManager::MarkAndPushClosure mark_and_push_closure(cm);
2082 ParCompactionManager::FollowStackClosure follow_stack_closure(cm);
2083
2084 // Need new claim bits before marking starts.
2085 ClassLoaderDataGraph::clear_claimed_marks();
2086
2087 {
2088 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer);
2089
2090 ParallelScavengeHeap::ParStrongRootsScope psrs;
2091
2092 GCTaskQueue* q = GCTaskQueue::create();
2093
2094 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2095 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2096 // We scan the thread roots in parallel
2097 Threads::create_thread_roots_marking_tasks(q);
2098 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2099 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
2100 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2101 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2102 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data));
2103 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2104 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2105
2106 if (active_gc_threads > 1) {
2107 for (uint j = 0; j < active_gc_threads; j++) {
2108 q->enqueue(new StealMarkingTask(&terminator));
2109 }
2110 }
2111
2112 gc_task_manager()->execute_and_wait(q);
2113 }
2114
2115 // Process reference objects found during marking
2116 {
2117 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
2118
2119 ReferenceProcessorStats stats;
2120 if (ref_processor()->processing_is_mt()) {
2121 RefProcTaskExecutor task_executor;
2122 stats = ref_processor()->process_discovered_references(
2123 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2124 &task_executor, &_gc_timer);
2125 } else {
2126 stats = ref_processor()->process_discovered_references(
2127 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
2128 &_gc_timer);
2129 }
2130
2131 gc_tracer->report_gc_reference_stats(stats);
2132 }
2133
2134 // This is the point where the entire marking should have completed.
2135 assert(cm->marking_stacks_empty(), "Marking should have completed");
2136
2137 {
2138 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer);
2139
2140 // Follow system dictionary roots and unload classes.
2141 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
2142
2143 // Unload nmethods.
2144 CodeCache::do_unloading(is_alive_closure(), purged_class);
2145
2146 // Prune dead klasses from subklass/sibling/implementor lists.
2147 Klass::clean_weak_klass_links(is_alive_closure());
2148 }
2149
2150 {
2151 GCTraceTime(Debug, gc, phases) t("Scrub String Table", &_gc_timer);
2152 // Delete entries for dead interned strings.
2153 StringTable::unlink(is_alive_closure());
2154 }
2155
2156 {
2157 GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", &_gc_timer);
2158 // Clean up unreferenced symbols in symbol table.
2159 SymbolTable::unlink();
2160 }
2161
2162 _gc_tracer.report_object_count_after_gc(is_alive_closure());
2163 }
2164
2165 void PSParallelCompact::adjust_roots(ParCompactionManager* cm) {
2166 // Adjust the pointers to reflect the new locations
2167 GCTraceTime(Info, gc, phases) tm("Adjust Roots", &_gc_timer);
2168
2169 // Need new claim bits when tracing through and adjusting pointers.
2170 ClassLoaderDataGraph::clear_claimed_marks();
2171
2172 PSParallelCompact::AdjustPointerClosure oop_closure(cm);
2173 PSParallelCompact::AdjustKlassClosure klass_closure(cm);
2174
2175 // General strong roots.
2176 Universe::oops_do(&oop_closure);
2177 JNIHandles::oops_do(&oop_closure); // Global (strong) JNI handles
2178 Threads::oops_do(&oop_closure, NULL);
2179 ObjectSynchronizer::oops_do(&oop_closure);
2180 FlatProfiler::oops_do(&oop_closure);
2181 Management::oops_do(&oop_closure);
2182 JvmtiExport::oops_do(&oop_closure);
2183 SystemDictionary::oops_do(&oop_closure);
2184 ClassLoaderDataGraph::oops_do(&oop_closure, &klass_closure, true);
2185
2186 // Now adjust pointers in remaining weak roots. (All of which should
2187 // have been cleared if they pointed to non-surviving objects.)
2188 // Global (weak) JNI handles
2189 JNIHandles::weak_oops_do(&oop_closure);
2190
2191 CodeBlobToOopClosure adjust_from_blobs(&oop_closure, CodeBlobToOopClosure::FixRelocations);
2192 CodeCache::blobs_do(&adjust_from_blobs);
2193 StringTable::oops_do(&oop_closure);
2194 ref_processor()->weak_oops_do(&oop_closure);
2195 // Roots were visited so references into the young gen in roots
2196 // may have been scanned. Process them also.
2197 // Should the reference processor have a span that excludes
2198 // young gen objects?
2199 PSScavenge::reference_processor()->weak_oops_do(&oop_closure);
2200 }
2201
2202 // Helper class to print 8 region numbers per line and then print the total at the end.
2203 class FillableRegionLogger : public StackObj {
2204 private:
2205 Log(gc, compaction) log;
2206 static const int LineLength = 8;
2207 size_t _regions[LineLength];
2208 int _next_index;
2209 bool _enabled;
2210 size_t _total_regions;
2211 public:
2212 FillableRegionLogger() : _next_index(0), _total_regions(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)) { }
2213 ~FillableRegionLogger() {
2214 log.trace(SIZE_FORMAT " initially fillable regions", _total_regions);
2215 }
2216
2217 void print_line() {
2218 if (!_enabled || _next_index == 0) {
2219 return;
2220 }
2221 FormatBuffer<> line("Fillable: ");
2222 for (int i = 0; i < _next_index; i++) {
2223 line.append(" " SIZE_FORMAT_W(7), _regions[i]);
2224 }
2225 log.trace("%s", line.buffer());
2226 _next_index = 0;
2227 }
2228
2229 void handle(size_t region) {
2230 if (!_enabled) {
2231 return;
2232 }
2233 _regions[_next_index++] = region;
2234 if (_next_index == LineLength) {
2235 print_line();
2236 }
2237 _total_regions++;
2238 }
2239 };
2240
2241 void PSParallelCompact::prepare_region_draining_tasks(GCTaskQueue* q,
2242 uint parallel_gc_threads)
2243 {
2244 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer);
2245
2246 // Find the threads that are active
2247 unsigned int which = 0;
2248
2249 // Find all regions that are available (can be filled immediately) and
2250 // distribute them to the thread stacks. The iteration is done in reverse
2251 // order (high to low) so the regions will be removed in ascending order.
2252
2253 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2254
2255 which = 0;
2256 // id + 1 is used to test termination so unsigned can
2257 // be used with an old_space_id == 0.
2258 FillableRegionLogger region_logger;
2259 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2260 SpaceInfo* const space_info = _space_info + id;
2261 MutableSpace* const space = space_info->space();
2262 HeapWord* const new_top = space_info->new_top();
2263
2264 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2265 const size_t end_region =
2266 sd.addr_to_region_idx(sd.region_align_up(new_top));
2267
2268 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2269 if (sd.region(cur)->claim_unsafe()) {
2270 ParCompactionManager* cm = ParCompactionManager::manager_array(which);
2271 cm->region_stack()->push(cur);
2272 region_logger.handle(cur);
2273 // Assign regions to tasks in round-robin fashion.
2274 if (++which == parallel_gc_threads) {
2275 which = 0;
2276 }
2277 }
2278 }
2279 region_logger.print_line();
2280 }
2281 }
2282
2283 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2284
2285 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2286 uint parallel_gc_threads) {
2287 GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer);
2288
2289 ParallelCompactData& sd = PSParallelCompact::summary_data();
2290
2291 // Iterate over all the spaces adding tasks for updating
2292 // regions in the dense prefix. Assume that 1 gc thread
2293 // will work on opening the gaps and the remaining gc threads
2294 // will work on the dense prefix.
2295 unsigned int space_id;
2296 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2297 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2298 const MutableSpace* const space = _space_info[space_id].space();
2299
2300 if (dense_prefix_end == space->bottom()) {
2301 // There is no dense prefix for this space.
2302 continue;
2303 }
2304
2305 // The dense prefix is before this region.
2306 size_t region_index_end_dense_prefix =
2307 sd.addr_to_region_idx(dense_prefix_end);
2308 RegionData* const dense_prefix_cp =
2309 sd.region(region_index_end_dense_prefix);
2310 assert(dense_prefix_end == space->end() ||
2311 dense_prefix_cp->available() ||
2312 dense_prefix_cp->claimed(),
2313 "The region after the dense prefix should always be ready to fill");
2314
2315 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2316
2317 // Is there dense prefix work?
2318 size_t total_dense_prefix_regions =
2319 region_index_end_dense_prefix - region_index_start;
2320 // How many regions of the dense prefix should be given to
2321 // each thread?
2322 if (total_dense_prefix_regions > 0) {
2323 uint tasks_for_dense_prefix = 1;
2324 if (total_dense_prefix_regions <=
2325 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2326 // Don't over partition. This assumes that
2327 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2328 // so there are not many regions to process.
2329 tasks_for_dense_prefix = parallel_gc_threads;
2330 } else {
2331 // Over partition
2332 tasks_for_dense_prefix = parallel_gc_threads *
2333 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2334 }
2335 size_t regions_per_thread = total_dense_prefix_regions /
2336 tasks_for_dense_prefix;
2337 // Give each thread at least 1 region.
2338 if (regions_per_thread == 0) {
2339 regions_per_thread = 1;
2340 }
2341
2342 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2343 if (region_index_start >= region_index_end_dense_prefix) {
2344 break;
2345 }
2346 // region_index_end is not processed
2347 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2348 region_index_end_dense_prefix);
2349 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2350 region_index_start,
2351 region_index_end));
2352 region_index_start = region_index_end;
2353 }
2354 }
2355 // This gets any part of the dense prefix that did not
2356 // fit evenly.
2357 if (region_index_start < region_index_end_dense_prefix) {
2358 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2359 region_index_start,
2360 region_index_end_dense_prefix));
2361 }
2362 }
2363 }
2364
2365 void PSParallelCompact::enqueue_region_stealing_tasks(
2366 GCTaskQueue* q,
2367 ParallelTaskTerminator* terminator_ptr,
2368 uint parallel_gc_threads) {
2369 GCTraceTime(Trace, gc, phases) tm("Steal Task Setup", &_gc_timer);
2370
2371 // Once a thread has drained it's stack, it should try to steal regions from
2372 // other threads.
2373 for (uint j = 0; j < parallel_gc_threads; j++) {
2374 q->enqueue(new StealRegionCompactionTask(terminator_ptr));
2375 }
2376 }
2377
2378 #ifdef ASSERT
2379 // Write a histogram of the number of times the block table was filled for a
2380 // region.
2381 void PSParallelCompact::write_block_fill_histogram()
2382 {
2383 if (!log_develop_is_enabled(Trace, gc, compaction)) {
2384 return;
2385 }
2386
2387 Log(gc, compaction) log;
2388 ResourceMark rm;
2389 outputStream* out = log.trace_stream();
2390
2391 typedef ParallelCompactData::RegionData rd_t;
2392 ParallelCompactData& sd = summary_data();
2393
2394 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2395 MutableSpace* const spc = _space_info[id].space();
2396 if (spc->bottom() != spc->top()) {
2397 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
2398 HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
2399 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
2400
2401 size_t histo[5] = { 0, 0, 0, 0, 0 };
2402 const size_t histo_len = sizeof(histo) / sizeof(size_t);
2403 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
2404
2405 for (const rd_t* cur = beg; cur < end; ++cur) {
2406 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
2407 }
2408 out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
2409 for (size_t i = 0; i < histo_len; ++i) {
2410 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
2411 histo[i], 100.0 * histo[i] / region_cnt);
2412 }
2413 out->cr();
2414 }
2415 }
2416 }
2417 #endif // #ifdef ASSERT
2418
2419 void PSParallelCompact::compact() {
2420 GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer);
2421
2422 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2423 PSOldGen* old_gen = heap->old_gen();
2424 old_gen->start_array()->reset();
2425 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2426 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2427 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2428 ParallelTaskTerminator terminator(active_gc_threads, qset);
2429
2430 GCTaskQueue* q = GCTaskQueue::create();
2431 prepare_region_draining_tasks(q, active_gc_threads);
2432 enqueue_dense_prefix_tasks(q, active_gc_threads);
2433 enqueue_region_stealing_tasks(q, &terminator, active_gc_threads);
2434
2435 {
2436 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer);
2437
2438 gc_task_manager()->execute_and_wait(q);
2439
2440 #ifdef ASSERT
2441 // Verify that all regions have been processed before the deferred updates.
2442 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2443 verify_complete(SpaceId(id));
2444 }
2445 #endif
2446 }
2447
2448 {
2449 // Update the deferred objects, if any. Any compaction manager can be used.
2450 GCTraceTime(Trace, gc, phases) tm("Deferred Updates", &_gc_timer);
2451 ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2452 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2453 update_deferred_objects(cm, SpaceId(id));
2454 }
2455 }
2456
2457 DEBUG_ONLY(write_block_fill_histogram());
2458 }
2459
2460 #ifdef ASSERT
2461 void PSParallelCompact::verify_complete(SpaceId space_id) {
2462 // All Regions between space bottom() to new_top() should be marked as filled
2463 // and all Regions between new_top() and top() should be available (i.e.,
2464 // should have been emptied).
2465 ParallelCompactData& sd = summary_data();
2466 SpaceInfo si = _space_info[space_id];
2467 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2468 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2469 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2470 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2471 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2472
2473 bool issued_a_warning = false;
2474
2475 size_t cur_region;
2476 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2477 const RegionData* const c = sd.region(cur_region);
2478 if (!c->completed()) {
2479 log_warning(gc)("region " SIZE_FORMAT " not filled: destination_count=%u",
2480 cur_region, c->destination_count());
2481 issued_a_warning = true;
2482 }
2483 }
2484
2485 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2486 const RegionData* const c = sd.region(cur_region);
2487 if (!c->available()) {
2488 log_warning(gc)("region " SIZE_FORMAT " not empty: destination_count=%u",
2489 cur_region, c->destination_count());
2490 issued_a_warning = true;
2491 }
2492 }
2493
2494 if (issued_a_warning) {
2495 print_region_ranges();
2496 }
2497 }
2498 #endif // #ifdef ASSERT
2499
2500 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) {
2501 _start_array->allocate_block(addr);
2502 compaction_manager()->update_contents(oop(addr));
2503 }
2504
2505 // Update interior oops in the ranges of regions [beg_region, end_region).
2506 void
2507 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2508 SpaceId space_id,
2509 size_t beg_region,
2510 size_t end_region) {
2511 ParallelCompactData& sd = summary_data();
2512 ParMarkBitMap* const mbm = mark_bitmap();
2513
2514 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2515 HeapWord* const end_addr = sd.region_to_addr(end_region);
2516 assert(beg_region <= end_region, "bad region range");
2517 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2518
2519 #ifdef ASSERT
2520 // Claim the regions to avoid triggering an assert when they are marked as
2521 // filled.
2522 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2523 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2524 }
2525 #endif // #ifdef ASSERT
2526
2527 if (beg_addr != space(space_id)->bottom()) {
2528 // Find the first live object or block of dead space that *starts* in this
2529 // range of regions. If a partial object crosses onto the region, skip it;
2530 // it will be marked for 'deferred update' when the object head is
2531 // processed. If dead space crosses onto the region, it is also skipped; it
2532 // will be filled when the prior region is processed. If neither of those
2533 // apply, the first word in the region is the start of a live object or dead
2534 // space.
2535 assert(beg_addr > space(space_id)->bottom(), "sanity");
2536 const RegionData* const cp = sd.region(beg_region);
2537 if (cp->partial_obj_size() != 0) {
2538 beg_addr = sd.partial_obj_end(beg_region);
2539 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2540 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2541 }
2542 }
2543
2544 if (beg_addr < end_addr) {
2545 // A live object or block of dead space starts in this range of Regions.
2546 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2547
2548 // Create closures and iterate.
2549 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2550 FillClosure fill_closure(cm, space_id);
2551 ParMarkBitMap::IterationStatus status;
2552 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2553 dense_prefix_end);
2554 if (status == ParMarkBitMap::incomplete) {
2555 update_closure.do_addr(update_closure.source());
2556 }
2557 }
2558
2559 // Mark the regions as filled.
2560 RegionData* const beg_cp = sd.region(beg_region);
2561 RegionData* const end_cp = sd.region(end_region);
2562 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2563 cp->set_completed();
2564 }
2565 }
2566
2567 // Return the SpaceId for the space containing addr. If addr is not in the
2568 // heap, last_space_id is returned. In debug mode it expects the address to be
2569 // in the heap and asserts such.
2570 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2571 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
2572
2573 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2574 if (_space_info[id].space()->contains(addr)) {
2575 return SpaceId(id);
2576 }
2577 }
2578
2579 assert(false, "no space contains the addr");
2580 return last_space_id;
2581 }
2582
2583 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2584 SpaceId id) {
2585 assert(id < last_space_id, "bad space id");
2586
2587 ParallelCompactData& sd = summary_data();
2588 const SpaceInfo* const space_info = _space_info + id;
2589 ObjectStartArray* const start_array = space_info->start_array();
2590
2591 const MutableSpace* const space = space_info->space();
2592 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2593 HeapWord* const beg_addr = space_info->dense_prefix();
2594 HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2595
2596 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2597 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2598 const RegionData* cur_region;
2599 for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2600 HeapWord* const addr = cur_region->deferred_obj_addr();
2601 if (addr != NULL) {
2602 if (start_array != NULL) {
2603 start_array->allocate_block(addr);
2604 }
2605 cm->update_contents(oop(addr));
2606 assert(oop(addr)->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(addr)));
2607 }
2608 }
2609 }
2610
2611 // Skip over count live words starting from beg, and return the address of the
2612 // next live word. Unless marked, the word corresponding to beg is assumed to
2613 // be dead. Callers must either ensure beg does not correspond to the middle of
2614 // an object, or account for those live words in some other way. Callers must
2615 // also ensure that there are enough live words in the range [beg, end) to skip.
2616 HeapWord*
2617 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2618 {
2619 assert(count > 0, "sanity");
2620
2621 ParMarkBitMap* m = mark_bitmap();
2622 idx_t bits_to_skip = m->words_to_bits(count);
2623 idx_t cur_beg = m->addr_to_bit(beg);
2624 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
2625
2626 do {
2627 cur_beg = m->find_obj_beg(cur_beg, search_end);
2628 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2629 const size_t obj_bits = cur_end - cur_beg + 1;
2630 if (obj_bits > bits_to_skip) {
2631 return m->bit_to_addr(cur_beg + bits_to_skip);
2632 }
2633 bits_to_skip -= obj_bits;
2634 cur_beg = cur_end + 1;
2635 } while (bits_to_skip > 0);
2636
2637 // Skipping the desired number of words landed just past the end of an object.
2638 // Find the start of the next object.
2639 cur_beg = m->find_obj_beg(cur_beg, search_end);
2640 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2641 return m->bit_to_addr(cur_beg);
2642 }
2643
2644 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2645 SpaceId src_space_id,
2646 size_t src_region_idx)
2647 {
2648 assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2649
2650 const SplitInfo& split_info = _space_info[src_space_id].split_info();
2651 if (split_info.dest_region_addr() == dest_addr) {
2652 // The partial object ending at the split point contains the first word to
2653 // be copied to dest_addr.
2654 return split_info.first_src_addr();
2655 }
2656
2657 const ParallelCompactData& sd = summary_data();
2658 ParMarkBitMap* const bitmap = mark_bitmap();
2659 const size_t RegionSize = ParallelCompactData::RegionSize;
2660
2661 assert(sd.is_region_aligned(dest_addr), "not aligned");
2662 const RegionData* const src_region_ptr = sd.region(src_region_idx);
2663 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2664 HeapWord* const src_region_destination = src_region_ptr->destination();
2665
2666 assert(dest_addr >= src_region_destination, "wrong src region");
2667 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2668
2669 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2670 HeapWord* const src_region_end = src_region_beg + RegionSize;
2671
2672 HeapWord* addr = src_region_beg;
2673 if (dest_addr == src_region_destination) {
2674 // Return the first live word in the source region.
2675 if (partial_obj_size == 0) {
2676 addr = bitmap->find_obj_beg(addr, src_region_end);
2677 assert(addr < src_region_end, "no objects start in src region");
2678 }
2679 return addr;
2680 }
2681
2682 // Must skip some live data.
2683 size_t words_to_skip = dest_addr - src_region_destination;
2684 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2685
2686 if (partial_obj_size >= words_to_skip) {
2687 // All the live words to skip are part of the partial object.
2688 addr += words_to_skip;
2689 if (partial_obj_size == words_to_skip) {
2690 // Find the first live word past the partial object.
2691 addr = bitmap->find_obj_beg(addr, src_region_end);
2692 assert(addr < src_region_end, "wrong src region");
2693 }
2694 return addr;
2695 }
2696
2697 // Skip over the partial object (if any).
2698 if (partial_obj_size != 0) {
2699 words_to_skip -= partial_obj_size;
2700 addr += partial_obj_size;
2701 }
2702
2703 // Skip over live words due to objects that start in the region.
2704 addr = skip_live_words(addr, src_region_end, words_to_skip);
2705 assert(addr < src_region_end, "wrong src region");
2706 return addr;
2707 }
2708
2709 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2710 SpaceId src_space_id,
2711 size_t beg_region,
2712 HeapWord* end_addr)
2713 {
2714 ParallelCompactData& sd = summary_data();
2715
2716 #ifdef ASSERT
2717 MutableSpace* const src_space = _space_info[src_space_id].space();
2718 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2719 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2720 "src_space_id does not match beg_addr");
2721 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2722 "src_space_id does not match end_addr");
2723 #endif // #ifdef ASSERT
2724
2725 RegionData* const beg = sd.region(beg_region);
2726 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2727
2728 // Regions up to new_top() are enqueued if they become available.
2729 HeapWord* const new_top = _space_info[src_space_id].new_top();
2730 RegionData* const enqueue_end =
2731 sd.addr_to_region_ptr(sd.region_align_up(new_top));
2732
2733 for (RegionData* cur = beg; cur < end; ++cur) {
2734 assert(cur->data_size() > 0, "region must have live data");
2735 cur->decrement_destination_count();
2736 if (cur < enqueue_end && cur->available() && cur->claim()) {
2737 cm->push_region(sd.region(cur));
2738 }
2739 }
2740 }
2741
2742 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2743 SpaceId& src_space_id,
2744 HeapWord*& src_space_top,
2745 HeapWord* end_addr)
2746 {
2747 typedef ParallelCompactData::RegionData RegionData;
2748
2749 ParallelCompactData& sd = PSParallelCompact::summary_data();
2750 const size_t region_size = ParallelCompactData::RegionSize;
2751
2752 size_t src_region_idx = 0;
2753
2754 // Skip empty regions (if any) up to the top of the space.
2755 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2756 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2757 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2758 const RegionData* const top_region_ptr =
2759 sd.addr_to_region_ptr(top_aligned_up);
2760 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2761 ++src_region_ptr;
2762 }
2763
2764 if (src_region_ptr < top_region_ptr) {
2765 // The next source region is in the current space. Update src_region_idx
2766 // and the source address to match src_region_ptr.
2767 src_region_idx = sd.region(src_region_ptr);
2768 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
2769 if (src_region_addr > closure.source()) {
2770 closure.set_source(src_region_addr);
2771 }
2772 return src_region_idx;
2773 }
2774
2775 // Switch to a new source space and find the first non-empty region.
2776 unsigned int space_id = src_space_id + 1;
2777 assert(space_id < last_space_id, "not enough spaces");
2778
2779 HeapWord* const destination = closure.destination();
2780
2781 do {
2782 MutableSpace* space = _space_info[space_id].space();
2783 HeapWord* const bottom = space->bottom();
2784 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
2785
2786 // Iterate over the spaces that do not compact into themselves.
2787 if (bottom_cp->destination() != bottom) {
2788 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
2789 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
2790
2791 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
2792 if (src_cp->live_obj_size() > 0) {
2793 // Found it.
2794 assert(src_cp->destination() == destination,
2795 "first live obj in the space must match the destination");
2796 assert(src_cp->partial_obj_size() == 0,
2797 "a space cannot begin with a partial obj");
2798
2799 src_space_id = SpaceId(space_id);
2800 src_space_top = space->top();
2801 const size_t src_region_idx = sd.region(src_cp);
2802 closure.set_source(sd.region_to_addr(src_region_idx));
2803 return src_region_idx;
2804 } else {
2805 assert(src_cp->data_size() == 0, "sanity");
2806 }
2807 }
2808 }
2809 } while (++space_id < last_space_id);
2810
2811 assert(false, "no source region was found");
2812 return 0;
2813 }
2814
2815 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
2816 {
2817 typedef ParMarkBitMap::IterationStatus IterationStatus;
2818 const size_t RegionSize = ParallelCompactData::RegionSize;
2819 ParMarkBitMap* const bitmap = mark_bitmap();
2820 ParallelCompactData& sd = summary_data();
2821 RegionData* const region_ptr = sd.region(region_idx);
2822
2823 // Get the items needed to construct the closure.
2824 HeapWord* dest_addr = sd.region_to_addr(region_idx);
2825 SpaceId dest_space_id = space_id(dest_addr);
2826 ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
2827 HeapWord* new_top = _space_info[dest_space_id].new_top();
2828 assert(dest_addr < new_top, "sanity");
2829 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
2830
2831 // Get the source region and related info.
2832 size_t src_region_idx = region_ptr->source_region();
2833 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2834 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2835
2836 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
2837 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2838
2839 // Adjust src_region_idx to prepare for decrementing destination counts (the
2840 // destination count is not decremented when a region is copied to itself).
2841 if (src_region_idx == region_idx) {
2842 src_region_idx += 1;
2843 }
2844
2845 if (bitmap->is_unmarked(closure.source())) {
2846 // The first source word is in the middle of an object; copy the remainder
2847 // of the object or as much as will fit. The fact that pointer updates were
2848 // deferred will be noted when the object header is processed.
2849 HeapWord* const old_src_addr = closure.source();
2850 closure.copy_partial_obj();
2851 if (closure.is_full()) {
2852 decrement_destination_counts(cm, src_space_id, src_region_idx,
2853 closure.source());
2854 region_ptr->set_deferred_obj_addr(NULL);
2855 region_ptr->set_completed();
2856 return;
2857 }
2858
2859 HeapWord* const end_addr = sd.region_align_down(closure.source());
2860 if (sd.region_align_down(old_src_addr) != end_addr) {
2861 // The partial object was copied from more than one source region.
2862 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2863
2864 // Move to the next source region, possibly switching spaces as well. All
2865 // args except end_addr may be modified.
2866 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2867 end_addr);
2868 }
2869 }
2870
2871 do {
2872 HeapWord* const cur_addr = closure.source();
2873 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2874 src_space_top);
2875 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
2876
2877 if (status == ParMarkBitMap::incomplete) {
2878 // The last obj that starts in the source region does not end in the
2879 // region.
2880 assert(closure.source() < end_addr, "sanity");
2881 HeapWord* const obj_beg = closure.source();
2882 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
2883 src_space_top);
2884 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
2885 if (obj_end < range_end) {
2886 // The end was found; the entire object will fit.
2887 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
2888 assert(status != ParMarkBitMap::would_overflow, "sanity");
2889 } else {
2890 // The end was not found; the object will not fit.
2891 assert(range_end < src_space_top, "obj cannot cross space boundary");
2892 status = ParMarkBitMap::would_overflow;
2893 }
2894 }
2895
2896 if (status == ParMarkBitMap::would_overflow) {
2897 // The last object did not fit. Note that interior oop updates were
2898 // deferred, then copy enough of the object to fill the region.
2899 region_ptr->set_deferred_obj_addr(closure.destination());
2900 status = closure.copy_until_full(); // copies from closure.source()
2901
2902 decrement_destination_counts(cm, src_space_id, src_region_idx,
2903 closure.source());
2904 region_ptr->set_completed();
2905 return;
2906 }
2907
2908 if (status == ParMarkBitMap::full) {
2909 decrement_destination_counts(cm, src_space_id, src_region_idx,
2910 closure.source());
2911 region_ptr->set_deferred_obj_addr(NULL);
2912 region_ptr->set_completed();
2913 return;
2914 }
2915
2916 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2917
2918 // Move to the next source region, possibly switching spaces as well. All
2919 // args except end_addr may be modified.
2920 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2921 end_addr);
2922 } while (true);
2923 }
2924
2925 void PSParallelCompact::fill_blocks(size_t region_idx)
2926 {
2927 // Fill in the block table elements for the specified region. Each block
2928 // table element holds the number of live words in the region that are to the
2929 // left of the first object that starts in the block. Thus only blocks in
2930 // which an object starts need to be filled.
2931 //
2932 // The algorithm scans the section of the bitmap that corresponds to the
2933 // region, keeping a running total of the live words. When an object start is
2934 // found, if it's the first to start in the block that contains it, the
2935 // current total is written to the block table element.
2936 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
2937 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
2938 const size_t RegionSize = ParallelCompactData::RegionSize;
2939
2940 ParallelCompactData& sd = summary_data();
2941 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
2942 if (partial_obj_size >= RegionSize) {
2943 return; // No objects start in this region.
2944 }
2945
2946 // Ensure the first loop iteration decides that the block has changed.
2947 size_t cur_block = sd.block_count();
2948
2949 const ParMarkBitMap* const bitmap = mark_bitmap();
2950
2951 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
2952 assert((size_t)1 << Log2BitsPerBlock ==
2953 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
2954
2955 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
2956 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
2957 size_t live_bits = bitmap->words_to_bits(partial_obj_size);
2958 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
2959 while (beg_bit < range_end) {
2960 const size_t new_block = beg_bit >> Log2BitsPerBlock;
2961 if (new_block != cur_block) {
2962 cur_block = new_block;
2963 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
2964 }
2965
2966 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
2967 if (end_bit < range_end - 1) {
2968 live_bits += end_bit - beg_bit + 1;
2969 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
2970 } else {
2971 return;
2972 }
2973 }
2974 }
2975
2976 void
2977 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
2978 const MutableSpace* sp = space(space_id);
2979 if (sp->is_empty()) {
2980 return;
2981 }
2982
2983 ParallelCompactData& sd = PSParallelCompact::summary_data();
2984 ParMarkBitMap* const bitmap = mark_bitmap();
2985 HeapWord* const dp_addr = dense_prefix(space_id);
2986 HeapWord* beg_addr = sp->bottom();
2987 HeapWord* end_addr = sp->top();
2988
2989 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
2990
2991 const size_t beg_region = sd.addr_to_region_idx(beg_addr);
2992 const size_t dp_region = sd.addr_to_region_idx(dp_addr);
2993 if (beg_region < dp_region) {
2994 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
2995 }
2996
2997 // The destination of the first live object that starts in the region is one
2998 // past the end of the partial object entering the region (if any).
2999 HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3000 HeapWord* const new_top = _space_info[space_id].new_top();
3001 assert(new_top >= dest_addr, "bad new_top value");
3002 const size_t words = pointer_delta(new_top, dest_addr);
3003
3004 if (words > 0) {
3005 ObjectStartArray* start_array = _space_info[space_id].start_array();
3006 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3007
3008 ParMarkBitMap::IterationStatus status;
3009 status = bitmap->iterate(&closure, dest_addr, end_addr);
3010 assert(status == ParMarkBitMap::full, "iteration not complete");
3011 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3012 "live objects skipped because closure is full");
3013 }
3014 }
3015
3016 jlong PSParallelCompact::millis_since_last_gc() {
3017 // We need a monotonically non-decreasing time in ms but
3018 // os::javaTimeMillis() does not guarantee monotonicity.
3019 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3020 jlong ret_val = now - _time_of_last_gc;
3021 // XXX See note in genCollectedHeap::millis_since_last_gc().
3022 if (ret_val < 0) {
3023 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);)
3024 return 0;
3025 }
3026 return ret_val;
3027 }
3028
3029 void PSParallelCompact::reset_millis_since_last_gc() {
3030 // We need a monotonically non-decreasing time in ms but
3031 // os::javaTimeMillis() does not guarantee monotonicity.
3032 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3033 }
3034
3035 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3036 {
3037 if (source() != destination()) {
3038 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3039 Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3040 }
3041 update_state(words_remaining());
3042 assert(is_full(), "sanity");
3043 return ParMarkBitMap::full;
3044 }
3045
3046 void MoveAndUpdateClosure::copy_partial_obj()
3047 {
3048 size_t words = words_remaining();
3049
3050 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3051 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3052 if (end_addr < range_end) {
3053 words = bitmap()->obj_size(source(), end_addr);
3054 }
3055
3056 // This test is necessary; if omitted, the pointer updates to a partial object
3057 // that crosses the dense prefix boundary could be overwritten.
3058 if (source() != destination()) {
3059 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3060 Copy::aligned_conjoint_words(source(), destination(), words);
3061 }
3062 update_state(words);
3063 }
3064
3065 void InstanceKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3066 PSParallelCompact::AdjustPointerClosure closure(cm);
3067 oop_oop_iterate_oop_maps<true>(obj, &closure);
3068 }
3069
3070 void InstanceMirrorKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3071 InstanceKlass::oop_pc_update_pointers(obj, cm);
3072
3073 PSParallelCompact::AdjustPointerClosure closure(cm);
3074 oop_oop_iterate_statics<true>(obj, &closure);
3075 }
3076
3077 void InstanceClassLoaderKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3078 InstanceKlass::oop_pc_update_pointers(obj, cm);
3079 }
3080
3081 #ifdef ASSERT
3082 template <class T> static void trace_reference_gc(const char *s, oop obj,
3083 T* referent_addr,
3084 T* next_addr,
3085 T* discovered_addr) {
3086 log_develop_trace(gc, ref)("%s obj " PTR_FORMAT, s, p2i(obj));
3087 log_develop_trace(gc, ref)(" referent_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3088 p2i(referent_addr), referent_addr ? p2i(oopDesc::load_decode_heap_oop(referent_addr)) : NULL);
3089 log_develop_trace(gc, ref)(" next_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3090 p2i(next_addr), next_addr ? p2i(oopDesc::load_decode_heap_oop(next_addr)) : NULL);
3091 log_develop_trace(gc, ref)(" discovered_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3092 p2i(discovered_addr), discovered_addr ? p2i(oopDesc::load_decode_heap_oop(discovered_addr)) : NULL);
3093 }
3094 #endif
3095
3096 template <class T>
3097 static void oop_pc_update_pointers_specialized(oop obj, ParCompactionManager* cm) {
3098 T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj);
3099 PSParallelCompact::adjust_pointer(referent_addr, cm);
3100 T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj);
3101 PSParallelCompact::adjust_pointer(next_addr, cm);
3102 T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj);
3103 PSParallelCompact::adjust_pointer(discovered_addr, cm);
3104 debug_only(trace_reference_gc("InstanceRefKlass::oop_update_ptrs", obj,
3105 referent_addr, next_addr, discovered_addr);)
3106 }
3107
3108 void InstanceRefKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3109 InstanceKlass::oop_pc_update_pointers(obj, cm);
3110
3111 if (UseCompressedOops) {
3112 oop_pc_update_pointers_specialized<narrowOop>(obj, cm);
3113 } else {
3114 oop_pc_update_pointers_specialized<oop>(obj, cm);
3115 }
3116 }
3117
3118 void ObjArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3119 assert(obj->is_objArray(), "obj must be obj array");
3120 PSParallelCompact::AdjustPointerClosure closure(cm);
3121 oop_oop_iterate_elements<true>(objArrayOop(obj), &closure);
3122 }
3123
3124 void TypeArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3125 assert(obj->is_typeArray(),"must be a type array");
3126 }
3127
3128 ParMarkBitMapClosure::IterationStatus
3129 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3130 assert(destination() != NULL, "sanity");
3131 assert(bitmap()->obj_size(addr) == words, "bad size");
3132
3133 _source = addr;
3134 assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) ==
3135 destination(), "wrong destination");
3136
3137 if (words > words_remaining()) {
3138 return ParMarkBitMap::would_overflow;
3139 }
3140
3141 // The start_array must be updated even if the object is not moving.
3142 if (_start_array != NULL) {
3143 _start_array->allocate_block(destination());
3144 }
3145
3146 if (destination() != source()) {
3147 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3148 Copy::aligned_conjoint_words(source(), destination(), words);
3149 }
3150
3151 oop moved_oop = (oop) destination();
3152 compaction_manager()->update_contents(moved_oop);
3153 assert(moved_oop->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop));
3154
3155 update_state(words);
3156 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3157 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3158 }
3159
3160 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3161 ParCompactionManager* cm,
3162 PSParallelCompact::SpaceId space_id) :
3163 ParMarkBitMapClosure(mbm, cm),
3164 _space_id(space_id),
3165 _start_array(PSParallelCompact::start_array(space_id))
3166 {
3167 }
3168
3169 // Updates the references in the object to their new values.
3170 ParMarkBitMapClosure::IterationStatus
3171 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3172 do_addr(addr);
3173 return ParMarkBitMap::incomplete;
3174 }
3175
3176 ParMarkBitMapClosure::IterationStatus
3177 FillClosure::do_addr(HeapWord* addr, size_t size) {
3178 CollectedHeap::fill_with_objects(addr, size);
3179 HeapWord* const end = addr + size;
3180 do {
3181 _start_array->allocate_block(addr);
3182 addr += oop(addr)->size();
3183 } while (addr < end);
3184 return ParMarkBitMap::incomplete;
3185 }