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 "aot/aotLoader.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "code/codeCache.hpp"
31 #include "gc/parallel/gcTaskManager.hpp"
32 #include "gc/parallel/parallelScavengeHeap.inline.hpp"
33 #include "gc/parallel/pcTasks.hpp"
34 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
35 #include "gc/parallel/psCompactionManager.inline.hpp"
36 #include "gc/parallel/psMarkSweep.hpp"
37 #include "gc/parallel/psMarkSweepDecorator.hpp"
38 #include "gc/parallel/psOldGen.hpp"
39 #include "gc/parallel/psParallelCompact.inline.hpp"
40 #include "gc/parallel/psPromotionManager.inline.hpp"
41 #include "gc/parallel/psScavenge.hpp"
42 #include "gc/parallel/psYoungGen.hpp"
43 #include "gc/shared/gcCause.hpp"
44 #include "gc/shared/gcHeapSummary.hpp"
45 #include "gc/shared/gcId.hpp"
46 #include "gc/shared/gcLocker.inline.hpp"
47 #include "gc/shared/gcTimer.hpp"
48 #include "gc/shared/gcTrace.hpp"
49 #include "gc/shared/gcTraceTime.inline.hpp"
50 #include "gc/shared/isGCActiveMark.hpp"
51 #include "gc/shared/referencePolicy.hpp"
52 #include "gc/shared/referenceProcessor.hpp"
53 #include "gc/shared/spaceDecorator.hpp"
54 #include "logging/log.hpp"
55 #include "memory/resourceArea.hpp"
56 #include "oops/instanceKlass.inline.hpp"
57 #include "oops/instanceMirrorKlass.inline.hpp"
58 #include "oops/methodData.hpp"
59 #include "oops/objArrayKlass.inline.hpp"
60 #include "oops/oop.inline.hpp"
61 #include "runtime/atomic.hpp"
62 #include "runtime/fprofiler.hpp"
63 #include "runtime/safepoint.hpp"
64 #include "runtime/vmThread.hpp"
65 #include "services/management.hpp"
66 #include "services/memTracker.hpp"
67 #include "services/memoryService.hpp"
68 #include "utilities/events.hpp"
69 #include "utilities/stack.inline.hpp"
70
71 #include <math.h>
72
73 // All sizes are in HeapWords.
74 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words
75 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
76 const size_t ParallelCompactData::RegionSizeBytes =
77 RegionSize << LogHeapWordSize;
78 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
79 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
80 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
81
82 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words
83 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize;
84 const size_t ParallelCompactData::BlockSizeBytes =
85 BlockSize << LogHeapWordSize;
86 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1;
87 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1;
88 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask;
89
90 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
91 const size_t ParallelCompactData::Log2BlocksPerRegion =
92 Log2RegionSize - Log2BlockSize;
93
94 const ParallelCompactData::RegionData::region_sz_t
95 ParallelCompactData::RegionData::dc_shift = 27;
96
97 const ParallelCompactData::RegionData::region_sz_t
98 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
99
100 const ParallelCompactData::RegionData::region_sz_t
101 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
102
103 const ParallelCompactData::RegionData::region_sz_t
104 ParallelCompactData::RegionData::los_mask = ~dc_mask;
105
106 const ParallelCompactData::RegionData::region_sz_t
107 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
108
109 const ParallelCompactData::RegionData::region_sz_t
110 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
111
112 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
113
114 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
115
116 double PSParallelCompact::_dwl_mean;
117 double PSParallelCompact::_dwl_std_dev;
118 double PSParallelCompact::_dwl_first_term;
119 double PSParallelCompact::_dwl_adjustment;
120 #ifdef ASSERT
121 bool PSParallelCompact::_dwl_initialized = false;
122 #endif // #ifdef ASSERT
123
124 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
125 HeapWord* destination)
126 {
127 assert(src_region_idx != 0, "invalid src_region_idx");
128 assert(partial_obj_size != 0, "invalid partial_obj_size argument");
129 assert(destination != NULL, "invalid destination argument");
130
131 _src_region_idx = src_region_idx;
132 _partial_obj_size = partial_obj_size;
133 _destination = destination;
134
135 // These fields may not be updated below, so make sure they're clear.
136 assert(_dest_region_addr == NULL, "should have been cleared");
137 assert(_first_src_addr == NULL, "should have been cleared");
138
139 // Determine the number of destination regions for the partial object.
140 HeapWord* const last_word = destination + partial_obj_size - 1;
141 const ParallelCompactData& sd = PSParallelCompact::summary_data();
142 HeapWord* const beg_region_addr = sd.region_align_down(destination);
143 HeapWord* const end_region_addr = sd.region_align_down(last_word);
144
145 if (beg_region_addr == end_region_addr) {
146 // One destination region.
147 _destination_count = 1;
148 if (end_region_addr == destination) {
149 // The destination falls on a region boundary, thus the first word of the
150 // partial object will be the first word copied to the destination region.
151 _dest_region_addr = end_region_addr;
152 _first_src_addr = sd.region_to_addr(src_region_idx);
153 }
154 } else {
155 // Two destination regions. When copied, the partial object will cross a
156 // destination region boundary, so a word somewhere within the partial
157 // object will be the first word copied to the second destination region.
158 _destination_count = 2;
159 _dest_region_addr = end_region_addr;
160 const size_t ofs = pointer_delta(end_region_addr, destination);
161 assert(ofs < _partial_obj_size, "sanity");
162 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
163 }
164 }
165
166 void SplitInfo::clear()
167 {
168 _src_region_idx = 0;
169 _partial_obj_size = 0;
170 _destination = NULL;
171 _destination_count = 0;
172 _dest_region_addr = NULL;
173 _first_src_addr = NULL;
174 assert(!is_valid(), "sanity");
175 }
176
177 #ifdef ASSERT
178 void SplitInfo::verify_clear()
179 {
180 assert(_src_region_idx == 0, "not clear");
181 assert(_partial_obj_size == 0, "not clear");
182 assert(_destination == NULL, "not clear");
183 assert(_destination_count == 0, "not clear");
184 assert(_dest_region_addr == NULL, "not clear");
185 assert(_first_src_addr == NULL, "not clear");
186 }
187 #endif // #ifdef ASSERT
188
189
190 void PSParallelCompact::print_on_error(outputStream* st) {
191 _mark_bitmap.print_on_error(st);
192 }
193
194 #ifndef PRODUCT
195 const char* PSParallelCompact::space_names[] = {
196 "old ", "eden", "from", "to "
197 };
198
199 void PSParallelCompact::print_region_ranges() {
200 if (!log_develop_is_enabled(Trace, gc, compaction)) {
201 return;
202 }
203 Log(gc, compaction) log;
204 ResourceMark rm;
205 Universe::print_on(log.trace_stream());
206 log.trace("space bottom top end new_top");
207 log.trace("------ ---------- ---------- ---------- ----------");
208
209 for (unsigned int id = 0; id < last_space_id; ++id) {
210 const MutableSpace* space = _space_info[id].space();
211 log.trace("%u %s "
212 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
213 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
214 id, space_names[id],
215 summary_data().addr_to_region_idx(space->bottom()),
216 summary_data().addr_to_region_idx(space->top()),
217 summary_data().addr_to_region_idx(space->end()),
218 summary_data().addr_to_region_idx(_space_info[id].new_top()));
219 }
220 }
221
222 void
223 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
224 {
225 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7)
226 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5)
227
228 ParallelCompactData& sd = PSParallelCompact::summary_data();
229 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
230 log_develop_trace(gc, compaction)(
231 REGION_IDX_FORMAT " " PTR_FORMAT " "
232 REGION_IDX_FORMAT " " PTR_FORMAT " "
233 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
234 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
235 i, p2i(c->data_location()), dci, p2i(c->destination()),
236 c->partial_obj_size(), c->live_obj_size(),
237 c->data_size(), c->source_region(), c->destination_count());
238
239 #undef REGION_IDX_FORMAT
240 #undef REGION_DATA_FORMAT
241 }
242
243 void
244 print_generic_summary_data(ParallelCompactData& summary_data,
245 HeapWord* const beg_addr,
246 HeapWord* const end_addr)
247 {
248 size_t total_words = 0;
249 size_t i = summary_data.addr_to_region_idx(beg_addr);
250 const size_t last = summary_data.addr_to_region_idx(end_addr);
251 HeapWord* pdest = 0;
252
253 while (i < last) {
254 ParallelCompactData::RegionData* c = summary_data.region(i);
255 if (c->data_size() != 0 || c->destination() != pdest) {
256 print_generic_summary_region(i, c);
257 total_words += c->data_size();
258 pdest = c->destination();
259 }
260 ++i;
261 }
262
263 log_develop_trace(gc, compaction)("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
264 }
265
266 void
267 print_generic_summary_data(ParallelCompactData& summary_data,
268 SpaceInfo* space_info)
269 {
270 if (!log_develop_is_enabled(Trace, gc, compaction)) {
271 return;
272 }
273
274 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
275 const MutableSpace* space = space_info[id].space();
276 print_generic_summary_data(summary_data, space->bottom(),
277 MAX2(space->top(), space_info[id].new_top()));
278 }
279 }
280
281 void
282 print_initial_summary_data(ParallelCompactData& summary_data,
283 const MutableSpace* space) {
284 if (space->top() == space->bottom()) {
285 return;
286 }
287
288 const size_t region_size = ParallelCompactData::RegionSize;
289 typedef ParallelCompactData::RegionData RegionData;
290 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
291 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
292 const RegionData* c = summary_data.region(end_region - 1);
293 HeapWord* end_addr = c->destination() + c->data_size();
294 const size_t live_in_space = pointer_delta(end_addr, space->bottom());
295
296 // Print (and count) the full regions at the beginning of the space.
297 size_t full_region_count = 0;
298 size_t i = summary_data.addr_to_region_idx(space->bottom());
299 while (i < end_region && summary_data.region(i)->data_size() == region_size) {
300 ParallelCompactData::RegionData* c = summary_data.region(i);
301 log_develop_trace(gc, compaction)(
302 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
303 i, p2i(c->destination()),
304 c->partial_obj_size(), c->live_obj_size(),
305 c->data_size(), c->source_region(), c->destination_count());
306 ++full_region_count;
307 ++i;
308 }
309
310 size_t live_to_right = live_in_space - full_region_count * region_size;
311
312 double max_reclaimed_ratio = 0.0;
313 size_t max_reclaimed_ratio_region = 0;
314 size_t max_dead_to_right = 0;
315 size_t max_live_to_right = 0;
316
317 // Print the 'reclaimed ratio' for regions while there is something live in
318 // the region or to the right of it. The remaining regions are empty (and
319 // uninteresting), and computing the ratio will result in division by 0.
320 while (i < end_region && live_to_right > 0) {
321 c = summary_data.region(i);
322 HeapWord* const region_addr = summary_data.region_to_addr(i);
323 const size_t used_to_right = pointer_delta(space->top(), region_addr);
324 const size_t dead_to_right = used_to_right - live_to_right;
325 const double reclaimed_ratio = double(dead_to_right) / live_to_right;
326
327 if (reclaimed_ratio > max_reclaimed_ratio) {
328 max_reclaimed_ratio = reclaimed_ratio;
329 max_reclaimed_ratio_region = i;
330 max_dead_to_right = dead_to_right;
331 max_live_to_right = live_to_right;
332 }
333
334 ParallelCompactData::RegionData* c = summary_data.region(i);
335 log_develop_trace(gc, compaction)(
336 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d"
337 "%12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
338 i, p2i(c->destination()),
339 c->partial_obj_size(), c->live_obj_size(),
340 c->data_size(), c->source_region(), c->destination_count(),
341 reclaimed_ratio, dead_to_right, live_to_right);
342
343
344 live_to_right -= c->data_size();
345 ++i;
346 }
347
348 // Any remaining regions are empty. Print one more if there is one.
349 if (i < end_region) {
350 ParallelCompactData::RegionData* c = summary_data.region(i);
351 log_develop_trace(gc, compaction)(
352 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
353 i, p2i(c->destination()),
354 c->partial_obj_size(), c->live_obj_size(),
355 c->data_size(), c->source_region(), c->destination_count());
356 }
357
358 log_develop_trace(gc, compaction)("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
359 max_reclaimed_ratio_region, max_dead_to_right, max_live_to_right, max_reclaimed_ratio);
360 }
361
362 void
363 print_initial_summary_data(ParallelCompactData& summary_data,
364 SpaceInfo* space_info) {
365 if (!log_develop_is_enabled(Trace, gc, compaction)) {
366 return;
367 }
368
369 unsigned int id = PSParallelCompact::old_space_id;
370 const MutableSpace* space;
371 do {
372 space = space_info[id].space();
373 print_initial_summary_data(summary_data, space);
374 } while (++id < PSParallelCompact::eden_space_id);
375
376 do {
377 space = space_info[id].space();
378 print_generic_summary_data(summary_data, space->bottom(), space->top());
379 } while (++id < PSParallelCompact::last_space_id);
380 }
381
382 void ParallelCompact_test() {
383 if (!UseParallelOldGC) {
384 return;
385 }
386 // Check that print_generic_summary_data() does not print the
387 // end region by placing a bad value in the destination of the
388 // end region. The end region should not be printed because it
389 // corresponds to the space after the end of the heap.
390 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
391 ParCompactionManager* const vmthread_cm =
392 ParCompactionManager::manager_array(ParallelGCThreads);
393 HeapWord* begin_heap =
394 (HeapWord*) heap->old_gen()->virtual_space()->low_boundary();
395 HeapWord* end_heap =
396 (HeapWord*) heap->young_gen()->virtual_space()->high_boundary();
397
398 print_generic_summary_data(PSParallelCompact::summary_data(),
399 begin_heap, end_heap);
400 }
401 #endif // #ifndef PRODUCT
402
403 #ifdef ASSERT
404 size_t add_obj_count;
405 size_t add_obj_size;
406 size_t mark_bitmap_count;
407 size_t mark_bitmap_size;
408 #endif // #ifdef ASSERT
409
410 ParallelCompactData::ParallelCompactData()
411 {
412 _region_start = 0;
413
414 _region_vspace = 0;
415 _reserved_byte_size = 0;
416 _region_data = 0;
417 _region_count = 0;
418
419 _block_vspace = 0;
420 _block_data = 0;
421 _block_count = 0;
422 }
423
424 bool ParallelCompactData::initialize(MemRegion covered_region)
425 {
426 _region_start = covered_region.start();
427 const size_t region_size = covered_region.word_size();
428 DEBUG_ONLY(_region_end = _region_start + region_size;)
429
430 assert(region_align_down(_region_start) == _region_start,
431 "region start not aligned");
432 assert((region_size & RegionSizeOffsetMask) == 0,
433 "region size not a multiple of RegionSize");
434
435 bool result = initialize_region_data(region_size) && initialize_block_data();
436 return result;
437 }
438
439 PSVirtualSpace*
440 ParallelCompactData::create_vspace(size_t count, size_t element_size)
441 {
442 const size_t raw_bytes = count * element_size;
443 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
444 const size_t granularity = os::vm_allocation_granularity();
445 _reserved_byte_size = align_size_up(raw_bytes, MAX2(page_sz, granularity));
446
447 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
448 MAX2(page_sz, granularity);
449 ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0);
450 os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, page_sz, rs.base(),
451 rs.size());
452
453 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
454
455 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
456 if (vspace != 0) {
457 if (vspace->expand_by(_reserved_byte_size)) {
458 return vspace;
459 }
460 delete vspace;
461 // Release memory reserved in the space.
462 rs.release();
463 }
464
465 return 0;
466 }
467
468 bool ParallelCompactData::initialize_region_data(size_t region_size)
469 {
470 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
471 _region_vspace = create_vspace(count, sizeof(RegionData));
472 if (_region_vspace != 0) {
473 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
474 _region_count = count;
475 return true;
476 }
477 return false;
478 }
479
480 bool ParallelCompactData::initialize_block_data()
481 {
482 assert(_region_count != 0, "region data must be initialized first");
483 const size_t count = _region_count << Log2BlocksPerRegion;
484 _block_vspace = create_vspace(count, sizeof(BlockData));
485 if (_block_vspace != 0) {
486 _block_data = (BlockData*)_block_vspace->reserved_low_addr();
487 _block_count = count;
488 return true;
489 }
490 return false;
491 }
492
493 void ParallelCompactData::clear()
494 {
495 memset(_region_data, 0, _region_vspace->committed_size());
496 memset(_block_data, 0, _block_vspace->committed_size());
497 }
498
499 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
500 assert(beg_region <= _region_count, "beg_region out of range");
501 assert(end_region <= _region_count, "end_region out of range");
502 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize");
503
504 const size_t region_cnt = end_region - beg_region;
505 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
506
507 const size_t beg_block = beg_region * BlocksPerRegion;
508 const size_t block_cnt = region_cnt * BlocksPerRegion;
509 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));
510 }
511
512 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
513 {
514 const RegionData* cur_cp = region(region_idx);
515 const RegionData* const end_cp = region(region_count() - 1);
516
517 HeapWord* result = region_to_addr(region_idx);
518 if (cur_cp < end_cp) {
519 do {
520 result += cur_cp->partial_obj_size();
521 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
522 }
523 return result;
524 }
525
526 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
527 {
528 const size_t obj_ofs = pointer_delta(addr, _region_start);
529 const size_t beg_region = obj_ofs >> Log2RegionSize;
530 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
531
532 DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
533 DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
534
535 if (beg_region == end_region) {
536 // All in one region.
537 _region_data[beg_region].add_live_obj(len);
538 return;
539 }
540
541 // First region.
542 const size_t beg_ofs = region_offset(addr);
543 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
544
545 Klass* klass = ((oop)addr)->klass();
546 // Middle regions--completely spanned by this object.
547 for (size_t region = beg_region + 1; region < end_region; ++region) {
548 _region_data[region].set_partial_obj_size(RegionSize);
549 _region_data[region].set_partial_obj_addr(addr);
550 }
551
552 // Last region.
553 const size_t end_ofs = region_offset(addr + len - 1);
554 _region_data[end_region].set_partial_obj_size(end_ofs + 1);
555 _region_data[end_region].set_partial_obj_addr(addr);
556 }
557
558 void
559 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
560 {
561 assert(region_offset(beg) == 0, "not RegionSize aligned");
562 assert(region_offset(end) == 0, "not RegionSize aligned");
563
564 size_t cur_region = addr_to_region_idx(beg);
565 const size_t end_region = addr_to_region_idx(end);
566 HeapWord* addr = beg;
567 while (cur_region < end_region) {
568 _region_data[cur_region].set_destination(addr);
569 _region_data[cur_region].set_destination_count(0);
570 _region_data[cur_region].set_source_region(cur_region);
571 _region_data[cur_region].set_data_location(addr);
572
573 // Update live_obj_size so the region appears completely full.
574 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
575 _region_data[cur_region].set_live_obj_size(live_size);
576
577 ++cur_region;
578 addr += RegionSize;
579 }
580 }
581
582 // Find the point at which a space can be split and, if necessary, record the
583 // split point.
584 //
585 // If the current src region (which overflowed the destination space) doesn't
586 // have a partial object, the split point is at the beginning of the current src
587 // region (an "easy" split, no extra bookkeeping required).
588 //
589 // If the current src region has a partial object, the split point is in the
590 // region where that partial object starts (call it the split_region). If
591 // split_region has a partial object, then the split point is just after that
592 // partial object (a "hard" split where we have to record the split data and
593 // zero the partial_obj_size field). With a "hard" split, we know that the
594 // partial_obj ends within split_region because the partial object that caused
595 // the overflow starts in split_region. If split_region doesn't have a partial
596 // obj, then the split is at the beginning of split_region (another "easy"
597 // split).
598 HeapWord*
599 ParallelCompactData::summarize_split_space(size_t src_region,
600 SplitInfo& split_info,
601 HeapWord* destination,
602 HeapWord* target_end,
603 HeapWord** target_next)
604 {
605 assert(destination <= target_end, "sanity");
606 assert(destination + _region_data[src_region].data_size() > target_end,
607 "region should not fit into target space");
608 assert(is_region_aligned(target_end), "sanity");
609
610 size_t split_region = src_region;
611 HeapWord* split_destination = destination;
612 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
613
614 if (destination + partial_obj_size > target_end) {
615 // The split point is just after the partial object (if any) in the
616 // src_region that contains the start of the object that overflowed the
617 // destination space.
618 //
619 // Find the start of the "overflow" object and set split_region to the
620 // region containing it.
621 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
622 split_region = addr_to_region_idx(overflow_obj);
623
624 // Clear the source_region field of all destination regions whose first word
625 // came from data after the split point (a non-null source_region field
626 // implies a region must be filled).
627 //
628 // An alternative to the simple loop below: clear during post_compact(),
629 // which uses memcpy instead of individual stores, and is easy to
630 // parallelize. (The downside is that it clears the entire RegionData
631 // object as opposed to just one field.)
632 //
633 // post_compact() would have to clear the summary data up to the highest
634 // address that was written during the summary phase, which would be
635 //
636 // max(top, max(new_top, clear_top))
637 //
638 // where clear_top is a new field in SpaceInfo. Would have to set clear_top
639 // to target_end.
640 const RegionData* const sr = region(split_region);
641 const size_t beg_idx =
642 addr_to_region_idx(region_align_up(sr->destination() +
643 sr->partial_obj_size()));
644 const size_t end_idx = addr_to_region_idx(target_end);
645
646 log_develop_trace(gc, compaction)("split: clearing source_region field in [" SIZE_FORMAT ", " SIZE_FORMAT ")", beg_idx, end_idx);
647 for (size_t idx = beg_idx; idx < end_idx; ++idx) {
648 _region_data[idx].set_source_region(0);
649 }
650
651 // Set split_destination and partial_obj_size to reflect the split region.
652 split_destination = sr->destination();
653 partial_obj_size = sr->partial_obj_size();
654 }
655
656 // The split is recorded only if a partial object extends onto the region.
657 if (partial_obj_size != 0) {
658 _region_data[split_region].set_partial_obj_size(0);
659 split_info.record(split_region, partial_obj_size, split_destination);
660 }
661
662 // Setup the continuation addresses.
663 *target_next = split_destination + partial_obj_size;
664 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
665
666 if (log_develop_is_enabled(Trace, gc, compaction)) {
667 const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
668 log_develop_trace(gc, compaction)("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT " pos=" SIZE_FORMAT,
669 split_type, p2i(source_next), split_region, partial_obj_size);
670 log_develop_trace(gc, compaction)("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT " tn=" PTR_FORMAT,
671 split_type, p2i(split_destination),
672 addr_to_region_idx(split_destination),
673 p2i(*target_next));
674
675 if (partial_obj_size != 0) {
676 HeapWord* const po_beg = split_info.destination();
677 HeapWord* const po_end = po_beg + split_info.partial_obj_size();
678 log_develop_trace(gc, compaction)("%s split: po_beg=" PTR_FORMAT " " SIZE_FORMAT " po_end=" PTR_FORMAT " " SIZE_FORMAT,
679 split_type,
680 p2i(po_beg), addr_to_region_idx(po_beg),
681 p2i(po_end), addr_to_region_idx(po_end));
682 }
683 }
684
685 return source_next;
686 }
687
688 bool ParallelCompactData::summarize(SplitInfo& split_info,
689 HeapWord* source_beg, HeapWord* source_end,
690 HeapWord** source_next,
691 HeapWord* target_beg, HeapWord* target_end,
692 HeapWord** target_next)
693 {
694 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
695 log_develop_trace(gc, compaction)(
696 "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
697 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
698 p2i(source_beg), p2i(source_end), p2i(source_next_val),
699 p2i(target_beg), p2i(target_end), p2i(*target_next));
700
701 size_t cur_region = addr_to_region_idx(source_beg);
702 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
703
704 HeapWord *dest_addr = target_beg;
705 while (cur_region < end_region) {
706 // The destination must be set even if the region has no data.
707 _region_data[cur_region].set_destination(dest_addr);
708
709 size_t words = _region_data[cur_region].data_size();
710 if (words > 0) {
711 // If cur_region does not fit entirely into the target space, find a point
712 // at which the source space can be 'split' so that part is copied to the
713 // target space and the rest is copied elsewhere.
714 if (dest_addr + words > target_end) {
715 assert(source_next != NULL, "source_next is NULL when splitting");
716 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
717 target_end, target_next);
718 return false;
719 }
720
721 // Compute the destination_count for cur_region, and if necessary, update
722 // source_region for a destination region. The source_region field is
723 // updated if cur_region is the first (left-most) region to be copied to a
724 // destination region.
725 //
726 // The destination_count calculation is a bit subtle. A region that has
727 // data that compacts into itself does not count itself as a destination.
728 // This maintains the invariant that a zero count means the region is
729 // available and can be claimed and then filled.
730 uint destination_count = 0;
731 if (split_info.is_split(cur_region)) {
732 // The current region has been split: the partial object will be copied
733 // to one destination space and the remaining data will be copied to
734 // another destination space. Adjust the initial destination_count and,
735 // if necessary, set the source_region field if the partial object will
736 // cross a destination region boundary.
737 destination_count = split_info.destination_count();
738 if (destination_count == 2) {
739 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
740 _region_data[dest_idx].set_source_region(cur_region);
741 }
742 }
743
744 HeapWord* const last_addr = dest_addr + words - 1;
745 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
746 const size_t dest_region_2 = addr_to_region_idx(last_addr);
747
748 // Initially assume that the destination regions will be the same and
749 // adjust the value below if necessary. Under this assumption, if
750 // cur_region == dest_region_2, then cur_region will be compacted
751 // completely into itself.
752 destination_count += cur_region == dest_region_2 ? 0 : 1;
753 if (dest_region_1 != dest_region_2) {
754 // Destination regions differ; adjust destination_count.
755 destination_count += 1;
756 // Data from cur_region will be copied to the start of dest_region_2.
757 _region_data[dest_region_2].set_source_region(cur_region);
758 } else if (region_offset(dest_addr) == 0) {
759 // Data from cur_region will be copied to the start of the destination
760 // region.
761 _region_data[dest_region_1].set_source_region(cur_region);
762 }
763
764 _region_data[cur_region].set_destination_count(destination_count);
765 _region_data[cur_region].set_data_location(region_to_addr(cur_region));
766 dest_addr += words;
767 }
768
769 ++cur_region;
770 }
771
772 *target_next = dest_addr;
773 return true;
774 }
775
776 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr, ParCompactionManager* cm) {
777 assert(addr != NULL, "Should detect NULL oop earlier");
778 assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap");
779 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked");
780
781 // Region covering the object.
782 RegionData* const region_ptr = addr_to_region_ptr(addr);
783 HeapWord* result = region_ptr->destination();
784
785 // If the entire Region is live, the new location is region->destination + the
786 // offset of the object within in the Region.
787
788 // Run some performance tests to determine if this special case pays off. It
789 // is worth it for pointers into the dense prefix. If the optimization to
790 // avoid pointer updates in regions that only point to the dense prefix is
791 // ever implemented, this should be revisited.
792 if (region_ptr->data_size() == RegionSize) {
793 result += region_offset(addr);
794 return result;
795 }
796
797 // Otherwise, the new location is region->destination + block offset + the
798 // number of live words in the Block that are (a) to the left of addr and (b)
799 // due to objects that start in the Block.
800
801 // Fill in the block table if necessary. This is unsynchronized, so multiple
802 // threads may fill the block table for a region (harmless, since it is
803 // idempotent).
804 if (!region_ptr->blocks_filled()) {
805 PSParallelCompact::fill_blocks(addr_to_region_idx(addr));
806 region_ptr->set_blocks_filled();
807 }
808
809 HeapWord* const search_start = block_align_down(addr);
810 const size_t block_offset = addr_to_block_ptr(addr)->offset();
811
812 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
813 const size_t live = bitmap->live_words_in_range(cm, search_start, oop(addr));
814 result += block_offset + live;
815 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result));
816 return result;
817 }
818
819 #ifdef ASSERT
820 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
821 {
822 const size_t* const beg = (const size_t*)vspace->committed_low_addr();
823 const size_t* const end = (const size_t*)vspace->committed_high_addr();
824 for (const size_t* p = beg; p < end; ++p) {
825 assert(*p == 0, "not zero");
826 }
827 }
828
829 void ParallelCompactData::verify_clear()
830 {
831 verify_clear(_region_vspace);
832 verify_clear(_block_vspace);
833 }
834 #endif // #ifdef ASSERT
835
836 STWGCTimer PSParallelCompact::_gc_timer;
837 ParallelOldTracer PSParallelCompact::_gc_tracer;
838 elapsedTimer PSParallelCompact::_accumulated_time;
839 unsigned int PSParallelCompact::_total_invocations = 0;
840 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
841 jlong PSParallelCompact::_time_of_last_gc = 0;
842 CollectorCounters* PSParallelCompact::_counters = NULL;
843 ParMarkBitMap PSParallelCompact::_mark_bitmap;
844 ParallelCompactData PSParallelCompact::_summary_data;
845
846 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
847
848 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
849
850 void PSParallelCompact::AdjustKlassClosure::do_klass(Klass* klass) {
851 PSParallelCompact::AdjustPointerClosure closure(_cm);
852 klass->oops_do(&closure);
853 }
854
855 void PSParallelCompact::post_initialize() {
856 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
857 MemRegion mr = heap->reserved_region();
858 _ref_processor =
859 new ReferenceProcessor(mr, // span
860 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
861 ParallelGCThreads, // mt processing degree
862 true, // mt discovery
863 ParallelGCThreads, // mt discovery degree
864 true, // atomic_discovery
865 &_is_alive_closure); // non-header is alive closure
866 _counters = new CollectorCounters("PSParallelCompact", 1);
867
868 // Initialize static fields in ParCompactionManager.
869 ParCompactionManager::initialize(mark_bitmap());
870 }
871
872 bool PSParallelCompact::initialize() {
873 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
874 MemRegion mr = heap->reserved_region();
875
876 // Was the old gen get allocated successfully?
877 if (!heap->old_gen()->is_allocated()) {
878 return false;
879 }
880
881 initialize_space_info();
882 initialize_dead_wood_limiter();
883
884 if (!_mark_bitmap.initialize(mr)) {
885 vm_shutdown_during_initialization(
886 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
887 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
888 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
889 return false;
890 }
891
892 if (!_summary_data.initialize(mr)) {
893 vm_shutdown_during_initialization(
894 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
895 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
896 _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
897 return false;
898 }
899
900 return true;
901 }
902
903 void PSParallelCompact::initialize_space_info()
904 {
905 memset(&_space_info, 0, sizeof(_space_info));
906
907 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
908 PSYoungGen* young_gen = heap->young_gen();
909
910 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
911 _space_info[eden_space_id].set_space(young_gen->eden_space());
912 _space_info[from_space_id].set_space(young_gen->from_space());
913 _space_info[to_space_id].set_space(young_gen->to_space());
914
915 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
916 }
917
918 void PSParallelCompact::initialize_dead_wood_limiter()
919 {
920 const size_t max = 100;
921 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
922 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
923 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
924 DEBUG_ONLY(_dwl_initialized = true;)
925 _dwl_adjustment = normal_distribution(1.0);
926 }
927
928 void
929 PSParallelCompact::clear_data_covering_space(SpaceId id)
930 {
931 // At this point, top is the value before GC, new_top() is the value that will
932 // be set at the end of GC. The marking bitmap is cleared to top; nothing
933 // should be marked above top. The summary data is cleared to the larger of
934 // top & new_top.
935 MutableSpace* const space = _space_info[id].space();
936 HeapWord* const bot = space->bottom();
937 HeapWord* const top = space->top();
938 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
939
940 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
941 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
942 _mark_bitmap.clear_range(beg_bit, end_bit);
943
944 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
945 const size_t end_region =
946 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
947 _summary_data.clear_range(beg_region, end_region);
948
949 // Clear the data used to 'split' regions.
950 SplitInfo& split_info = _space_info[id].split_info();
951 if (split_info.is_valid()) {
952 split_info.clear();
953 }
954 DEBUG_ONLY(split_info.verify_clear();)
955 }
956
957 void PSParallelCompact::pre_compact()
958 {
959 // Update the from & to space pointers in space_info, since they are swapped
960 // at each young gen gc. Do the update unconditionally (even though a
961 // promotion failure does not swap spaces) because an unknown number of young
962 // collections will have swapped the spaces an unknown number of times.
963 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer);
964 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
965 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
966 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
967
968 DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
969 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
970
971 // Increment the invocation count
972 heap->increment_total_collections(true);
973
974 // We need to track unique mark sweep invocations as well.
975 _total_invocations++;
976
977 heap->print_heap_before_gc();
978 heap->trace_heap_before_gc(&_gc_tracer);
979
980 // Fill in TLABs
981 heap->accumulate_statistics_all_tlabs();
982 heap->ensure_parsability(true); // retire TLABs
983
984 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
985 HandleMark hm; // Discard invalid handles created during verification
986 Universe::verify("Before GC");
987 }
988
989 // Verify object start arrays
990 if (VerifyObjectStartArray &&
991 VerifyBeforeGC) {
992 heap->old_gen()->verify_object_start_array();
993 }
994
995 DEBUG_ONLY(mark_bitmap()->verify_clear();)
996 DEBUG_ONLY(summary_data().verify_clear();)
997
998 // Have worker threads release resources the next time they run a task.
999 gc_task_manager()->release_all_resources();
1000
1001 ParCompactionManager::reset_all_bitmap_query_caches();
1002 }
1003
1004 void PSParallelCompact::post_compact()
1005 {
1006 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer);
1007
1008 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1009 // Clear the marking bitmap, summary data and split info.
1010 clear_data_covering_space(SpaceId(id));
1011 // Update top(). Must be done after clearing the bitmap and summary data.
1012 _space_info[id].publish_new_top();
1013 }
1014
1015 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1016 MutableSpace* const from_space = _space_info[from_space_id].space();
1017 MutableSpace* const to_space = _space_info[to_space_id].space();
1018
1019 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1020 bool eden_empty = eden_space->is_empty();
1021 if (!eden_empty) {
1022 eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1023 heap->young_gen(), heap->old_gen());
1024 }
1025
1026 // Update heap occupancy information which is used as input to the soft ref
1027 // clearing policy at the next gc.
1028 Universe::update_heap_info_at_gc();
1029
1030 bool young_gen_empty = eden_empty && from_space->is_empty() &&
1031 to_space->is_empty();
1032
1033 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set());
1034 MemRegion old_mr = heap->old_gen()->reserved();
1035 if (young_gen_empty) {
1036 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
1037 } else {
1038 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1039 }
1040
1041 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1042 ClassLoaderDataGraph::purge();
1043 MetaspaceAux::verify_metrics();
1044
1045 CodeCache::gc_epilogue();
1046 JvmtiExport::gc_epilogue();
1047
1048 #if defined(COMPILER2) || INCLUDE_JVMCI
1049 DerivedPointerTable::update_pointers();
1050 #endif
1051
1052 ref_processor()->enqueue_discovered_references(NULL);
1053
1054 if (ZapUnusedHeapArea) {
1055 heap->gen_mangle_unused_area();
1056 }
1057
1058 // Update time of last GC
1059 reset_millis_since_last_gc();
1060 }
1061
1062 HeapWord*
1063 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1064 bool maximum_compaction)
1065 {
1066 const size_t region_size = ParallelCompactData::RegionSize;
1067 const ParallelCompactData& sd = summary_data();
1068
1069 const MutableSpace* const space = _space_info[id].space();
1070 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1071 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1072 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1073
1074 // Skip full regions at the beginning of the space--they are necessarily part
1075 // of the dense prefix.
1076 size_t full_count = 0;
1077 const RegionData* cp;
1078 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1079 ++full_count;
1080 }
1081
1082 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1083 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1084 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1085 if (maximum_compaction || cp == end_cp || interval_ended) {
1086 _maximum_compaction_gc_num = total_invocations();
1087 return sd.region_to_addr(cp);
1088 }
1089
1090 HeapWord* const new_top = _space_info[id].new_top();
1091 const size_t space_live = pointer_delta(new_top, space->bottom());
1092 const size_t space_used = space->used_in_words();
1093 const size_t space_capacity = space->capacity_in_words();
1094
1095 const double cur_density = double(space_live) / space_capacity;
1096 const double deadwood_density =
1097 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1098 const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1099
1100 if (TraceParallelOldGCDensePrefix) {
1101 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1102 cur_density, deadwood_density, deadwood_goal);
1103 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1104 "space_cap=" SIZE_FORMAT,
1105 space_live, space_used,
1106 space_capacity);
1107 }
1108
1109 // XXX - Use binary search?
1110 HeapWord* dense_prefix = sd.region_to_addr(cp);
1111 const RegionData* full_cp = cp;
1112 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1113 while (cp < end_cp) {
1114 HeapWord* region_destination = cp->destination();
1115 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1116 if (TraceParallelOldGCDensePrefix && Verbose) {
1117 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1118 "dp=" PTR_FORMAT " " "cdw=" SIZE_FORMAT_W(8),
1119 sd.region(cp), p2i(region_destination),
1120 p2i(dense_prefix), cur_deadwood);
1121 }
1122
1123 if (cur_deadwood >= deadwood_goal) {
1124 // Found the region that has the correct amount of deadwood to the left.
1125 // This typically occurs after crossing a fairly sparse set of regions, so
1126 // iterate backwards over those sparse regions, looking for the region
1127 // that has the lowest density of live objects 'to the right.'
1128 size_t space_to_left = sd.region(cp) * region_size;
1129 size_t live_to_left = space_to_left - cur_deadwood;
1130 size_t space_to_right = space_capacity - space_to_left;
1131 size_t live_to_right = space_live - live_to_left;
1132 double density_to_right = double(live_to_right) / space_to_right;
1133 while (cp > full_cp) {
1134 --cp;
1135 const size_t prev_region_live_to_right = live_to_right -
1136 cp->data_size();
1137 const size_t prev_region_space_to_right = space_to_right + region_size;
1138 double prev_region_density_to_right =
1139 double(prev_region_live_to_right) / prev_region_space_to_right;
1140 if (density_to_right <= prev_region_density_to_right) {
1141 return dense_prefix;
1142 }
1143 if (TraceParallelOldGCDensePrefix && Verbose) {
1144 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1145 "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1146 prev_region_density_to_right);
1147 }
1148 dense_prefix -= region_size;
1149 live_to_right = prev_region_live_to_right;
1150 space_to_right = prev_region_space_to_right;
1151 density_to_right = prev_region_density_to_right;
1152 }
1153 return dense_prefix;
1154 }
1155
1156 dense_prefix += region_size;
1157 ++cp;
1158 }
1159
1160 return dense_prefix;
1161 }
1162
1163 #ifndef PRODUCT
1164 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1165 const SpaceId id,
1166 const bool maximum_compaction,
1167 HeapWord* const addr)
1168 {
1169 const size_t region_idx = summary_data().addr_to_region_idx(addr);
1170 RegionData* const cp = summary_data().region(region_idx);
1171 const MutableSpace* const space = _space_info[id].space();
1172 HeapWord* const new_top = _space_info[id].new_top();
1173
1174 const size_t space_live = pointer_delta(new_top, space->bottom());
1175 const size_t dead_to_left = pointer_delta(addr, cp->destination());
1176 const size_t space_cap = space->capacity_in_words();
1177 const double dead_to_left_pct = double(dead_to_left) / space_cap;
1178 const size_t live_to_right = new_top - cp->destination();
1179 const size_t dead_to_right = space->top() - addr - live_to_right;
1180
1181 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1182 "spl=" SIZE_FORMAT " "
1183 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1184 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1185 " ratio=%10.8f",
1186 algorithm, p2i(addr), region_idx,
1187 space_live,
1188 dead_to_left, dead_to_left_pct,
1189 dead_to_right, live_to_right,
1190 double(dead_to_right) / live_to_right);
1191 }
1192 #endif // #ifndef PRODUCT
1193
1194 // Return a fraction indicating how much of the generation can be treated as
1195 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution
1196 // based on the density of live objects in the generation to determine a limit,
1197 // which is then adjusted so the return value is min_percent when the density is
1198 // 1.
1199 //
1200 // The following table shows some return values for a different values of the
1201 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1202 // min_percent is 1.
1203 //
1204 // fraction allowed as dead wood
1205 // -----------------------------------------------------------------
1206 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1207 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1208 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1209 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1210 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1211 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1212 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1213 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1214 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1215 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1216 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1217 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1218 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1219 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1220 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1221 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1222 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1223 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1224 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1225 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1226 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1227 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1228 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1229
1230 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1231 {
1232 assert(_dwl_initialized, "uninitialized");
1233
1234 // The raw limit is the value of the normal distribution at x = density.
1235 const double raw_limit = normal_distribution(density);
1236
1237 // Adjust the raw limit so it becomes the minimum when the density is 1.
1238 //
1239 // First subtract the adjustment value (which is simply the precomputed value
1240 // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1241 // Then add the minimum value, so the minimum is returned when the density is
1242 // 1. Finally, prevent negative values, which occur when the mean is not 0.5.
1243 const double min = double(min_percent) / 100.0;
1244 const double limit = raw_limit - _dwl_adjustment + min;
1245 return MAX2(limit, 0.0);
1246 }
1247
1248 ParallelCompactData::RegionData*
1249 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1250 const RegionData* end)
1251 {
1252 const size_t region_size = ParallelCompactData::RegionSize;
1253 ParallelCompactData& sd = summary_data();
1254 size_t left = sd.region(beg);
1255 size_t right = end > beg ? sd.region(end) - 1 : left;
1256
1257 // Binary search.
1258 while (left < right) {
1259 // Equivalent to (left + right) / 2, but does not overflow.
1260 const size_t middle = left + (right - left) / 2;
1261 RegionData* const middle_ptr = sd.region(middle);
1262 HeapWord* const dest = middle_ptr->destination();
1263 HeapWord* const addr = sd.region_to_addr(middle);
1264 assert(dest != NULL, "sanity");
1265 assert(dest <= addr, "must move left");
1266
1267 if (middle > left && dest < addr) {
1268 right = middle - 1;
1269 } else if (middle < right && middle_ptr->data_size() == region_size) {
1270 left = middle + 1;
1271 } else {
1272 return middle_ptr;
1273 }
1274 }
1275 return sd.region(left);
1276 }
1277
1278 ParallelCompactData::RegionData*
1279 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1280 const RegionData* end,
1281 size_t dead_words)
1282 {
1283 ParallelCompactData& sd = summary_data();
1284 size_t left = sd.region(beg);
1285 size_t right = end > beg ? sd.region(end) - 1 : left;
1286
1287 // Binary search.
1288 while (left < right) {
1289 // Equivalent to (left + right) / 2, but does not overflow.
1290 const size_t middle = left + (right - left) / 2;
1291 RegionData* const middle_ptr = sd.region(middle);
1292 HeapWord* const dest = middle_ptr->destination();
1293 HeapWord* const addr = sd.region_to_addr(middle);
1294 assert(dest != NULL, "sanity");
1295 assert(dest <= addr, "must move left");
1296
1297 const size_t dead_to_left = pointer_delta(addr, dest);
1298 if (middle > left && dead_to_left > dead_words) {
1299 right = middle - 1;
1300 } else if (middle < right && dead_to_left < dead_words) {
1301 left = middle + 1;
1302 } else {
1303 return middle_ptr;
1304 }
1305 }
1306 return sd.region(left);
1307 }
1308
1309 // The result is valid during the summary phase, after the initial summarization
1310 // of each space into itself, and before final summarization.
1311 inline double
1312 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1313 HeapWord* const bottom,
1314 HeapWord* const top,
1315 HeapWord* const new_top)
1316 {
1317 ParallelCompactData& sd = summary_data();
1318
1319 assert(cp != NULL, "sanity");
1320 assert(bottom != NULL, "sanity");
1321 assert(top != NULL, "sanity");
1322 assert(new_top != NULL, "sanity");
1323 assert(top >= new_top, "summary data problem?");
1324 assert(new_top > bottom, "space is empty; should not be here");
1325 assert(new_top >= cp->destination(), "sanity");
1326 assert(top >= sd.region_to_addr(cp), "sanity");
1327
1328 HeapWord* const destination = cp->destination();
1329 const size_t dense_prefix_live = pointer_delta(destination, bottom);
1330 const size_t compacted_region_live = pointer_delta(new_top, destination);
1331 const size_t compacted_region_used = pointer_delta(top,
1332 sd.region_to_addr(cp));
1333 const size_t reclaimable = compacted_region_used - compacted_region_live;
1334
1335 const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1336 return double(reclaimable) / divisor;
1337 }
1338
1339 // Return the address of the end of the dense prefix, a.k.a. the start of the
1340 // compacted region. The address is always on a region boundary.
1341 //
1342 // Completely full regions at the left are skipped, since no compaction can
1343 // occur in those regions. Then the maximum amount of dead wood to allow is
1344 // computed, based on the density (amount live / capacity) of the generation;
1345 // the region with approximately that amount of dead space to the left is
1346 // identified as the limit region. Regions between the last completely full
1347 // region and the limit region are scanned and the one that has the best
1348 // (maximum) reclaimed_ratio() is selected.
1349 HeapWord*
1350 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1351 bool maximum_compaction)
1352 {
1353 const size_t region_size = ParallelCompactData::RegionSize;
1354 const ParallelCompactData& sd = summary_data();
1355
1356 const MutableSpace* const space = _space_info[id].space();
1357 HeapWord* const top = space->top();
1358 HeapWord* const top_aligned_up = sd.region_align_up(top);
1359 HeapWord* const new_top = _space_info[id].new_top();
1360 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1361 HeapWord* const bottom = space->bottom();
1362 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1363 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1364 const RegionData* const new_top_cp =
1365 sd.addr_to_region_ptr(new_top_aligned_up);
1366
1367 // Skip full regions at the beginning of the space--they are necessarily part
1368 // of the dense prefix.
1369 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1370 assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1371 space->is_empty(), "no dead space allowed to the left");
1372 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1373 "region must have dead space");
1374
1375 // The gc number is saved whenever a maximum compaction is done, and used to
1376 // determine when the maximum compaction interval has expired. This avoids
1377 // successive max compactions for different reasons.
1378 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1379 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1380 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1381 total_invocations() == HeapFirstMaximumCompactionCount;
1382 if (maximum_compaction || full_cp == top_cp || interval_ended) {
1383 _maximum_compaction_gc_num = total_invocations();
1384 return sd.region_to_addr(full_cp);
1385 }
1386
1387 const size_t space_live = pointer_delta(new_top, bottom);
1388 const size_t space_used = space->used_in_words();
1389 const size_t space_capacity = space->capacity_in_words();
1390
1391 const double density = double(space_live) / double(space_capacity);
1392 const size_t min_percent_free = MarkSweepDeadRatio;
1393 const double limiter = dead_wood_limiter(density, min_percent_free);
1394 const size_t dead_wood_max = space_used - space_live;
1395 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1396 dead_wood_max);
1397
1398 if (TraceParallelOldGCDensePrefix) {
1399 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1400 "space_cap=" SIZE_FORMAT,
1401 space_live, space_used,
1402 space_capacity);
1403 tty->print_cr("dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f "
1404 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1405 density, min_percent_free, limiter,
1406 dead_wood_max, dead_wood_limit);
1407 }
1408
1409 // Locate the region with the desired amount of dead space to the left.
1410 const RegionData* const limit_cp =
1411 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1412
1413 // Scan from the first region with dead space to the limit region and find the
1414 // one with the best (largest) reclaimed ratio.
1415 double best_ratio = 0.0;
1416 const RegionData* best_cp = full_cp;
1417 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1418 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1419 if (tmp_ratio > best_ratio) {
1420 best_cp = cp;
1421 best_ratio = tmp_ratio;
1422 }
1423 }
1424
1425 return sd.region_to_addr(best_cp);
1426 }
1427
1428 void PSParallelCompact::summarize_spaces_quick()
1429 {
1430 for (unsigned int i = 0; i < last_space_id; ++i) {
1431 const MutableSpace* space = _space_info[i].space();
1432 HeapWord** nta = _space_info[i].new_top_addr();
1433 bool result = _summary_data.summarize(_space_info[i].split_info(),
1434 space->bottom(), space->top(), NULL,
1435 space->bottom(), space->end(), nta);
1436 assert(result, "space must fit into itself");
1437 _space_info[i].set_dense_prefix(space->bottom());
1438 }
1439 }
1440
1441 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1442 {
1443 HeapWord* const dense_prefix_end = dense_prefix(id);
1444 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1445 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1446 if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1447 // Only enough dead space is filled so that any remaining dead space to the
1448 // left is larger than the minimum filler object. (The remainder is filled
1449 // during the copy/update phase.)
1450 //
1451 // The size of the dead space to the right of the boundary is not a
1452 // concern, since compaction will be able to use whatever space is
1453 // available.
1454 //
1455 // Here '||' is the boundary, 'x' represents a don't care bit and a box
1456 // surrounds the space to be filled with an object.
1457 //
1458 // In the 32-bit VM, each bit represents two 32-bit words:
1459 // +---+
1460 // a) beg_bits: ... x x x | 0 | || 0 x x ...
1461 // end_bits: ... x x x | 0 | || 0 x x ...
1462 // +---+
1463 //
1464 // In the 64-bit VM, each bit represents one 64-bit word:
1465 // +------------+
1466 // b) beg_bits: ... x x x | 0 || 0 | x x ...
1467 // end_bits: ... x x 1 | 0 || 0 | x x ...
1468 // +------------+
1469 // +-------+
1470 // c) beg_bits: ... x x | 0 0 | || 0 x x ...
1471 // end_bits: ... x 1 | 0 0 | || 0 x x ...
1472 // +-------+
1473 // +-----------+
1474 // d) beg_bits: ... x | 0 0 0 | || 0 x x ...
1475 // end_bits: ... 1 | 0 0 0 | || 0 x x ...
1476 // +-----------+
1477 // +-------+
1478 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ...
1479 // end_bits: ... 0 0 | 0 0 | || 0 x x ...
1480 // +-------+
1481
1482 // Initially assume case a, c or e will apply.
1483 size_t obj_len = CollectedHeap::min_fill_size();
1484 HeapWord* obj_beg = dense_prefix_end - obj_len;
1485
1486 #ifdef _LP64
1487 if (MinObjAlignment > 1) { // object alignment > heap word size
1488 // Cases a, c or e.
1489 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1490 // Case b above.
1491 obj_beg = dense_prefix_end - 1;
1492 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1493 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1494 // Case d above.
1495 obj_beg = dense_prefix_end - 3;
1496 obj_len = 3;
1497 }
1498 #endif // #ifdef _LP64
1499
1500 CollectedHeap::fill_with_object(obj_beg, obj_len);
1501 _mark_bitmap.mark_obj(obj_beg, obj_len);
1502 _summary_data.add_obj(obj_beg, obj_len);
1503 assert(start_array(id) != NULL, "sanity");
1504 start_array(id)->allocate_block(obj_beg);
1505 }
1506 }
1507
1508 void
1509 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1510 {
1511 assert(id < last_space_id, "id out of range");
1512 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(),
1513 "should have been reset in summarize_spaces_quick()");
1514
1515 const MutableSpace* space = _space_info[id].space();
1516 if (_space_info[id].new_top() != space->bottom()) {
1517 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1518 _space_info[id].set_dense_prefix(dense_prefix_end);
1519
1520 #ifndef PRODUCT
1521 if (TraceParallelOldGCDensePrefix) {
1522 print_dense_prefix_stats("ratio", id, maximum_compaction,
1523 dense_prefix_end);
1524 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1525 print_dense_prefix_stats("density", id, maximum_compaction, addr);
1526 }
1527 #endif // #ifndef PRODUCT
1528
1529 // Recompute the summary data, taking into account the dense prefix. If
1530 // every last byte will be reclaimed, then the existing summary data which
1531 // compacts everything can be left in place.
1532 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1533 // If dead space crosses the dense prefix boundary, it is (at least
1534 // partially) filled with a dummy object, marked live and added to the
1535 // summary data. This simplifies the copy/update phase and must be done
1536 // before the final locations of objects are determined, to prevent
1537 // leaving a fragment of dead space that is too small to fill.
1538 fill_dense_prefix_end(id);
1539
1540 // Compute the destination of each Region, and thus each object.
1541 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1542 _summary_data.summarize(_space_info[id].split_info(),
1543 dense_prefix_end, space->top(), NULL,
1544 dense_prefix_end, space->end(),
1545 _space_info[id].new_top_addr());
1546 }
1547 }
1548
1549 if (log_develop_is_enabled(Trace, gc, compaction)) {
1550 const size_t region_size = ParallelCompactData::RegionSize;
1551 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1552 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1553 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1554 HeapWord* const new_top = _space_info[id].new_top();
1555 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1556 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1557 log_develop_trace(gc, compaction)(
1558 "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1559 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1560 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1561 id, space->capacity_in_words(), p2i(dense_prefix_end),
1562 dp_region, dp_words / region_size,
1563 cr_words / region_size, p2i(new_top));
1564 }
1565 }
1566
1567 #ifndef PRODUCT
1568 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1569 HeapWord* dst_beg, HeapWord* dst_end,
1570 SpaceId src_space_id,
1571 HeapWord* src_beg, HeapWord* src_end)
1572 {
1573 log_develop_trace(gc, compaction)(
1574 "Summarizing %d [%s] into %d [%s]: "
1575 "src=" PTR_FORMAT "-" PTR_FORMAT " "
1576 SIZE_FORMAT "-" SIZE_FORMAT " "
1577 "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1578 SIZE_FORMAT "-" SIZE_FORMAT,
1579 src_space_id, space_names[src_space_id],
1580 dst_space_id, space_names[dst_space_id],
1581 p2i(src_beg), p2i(src_end),
1582 _summary_data.addr_to_region_idx(src_beg),
1583 _summary_data.addr_to_region_idx(src_end),
1584 p2i(dst_beg), p2i(dst_end),
1585 _summary_data.addr_to_region_idx(dst_beg),
1586 _summary_data.addr_to_region_idx(dst_end));
1587 }
1588 #endif // #ifndef PRODUCT
1589
1590 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1591 bool maximum_compaction)
1592 {
1593 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer);
1594
1595 #ifdef ASSERT
1596 if (TraceParallelOldGCMarkingPhase) {
1597 tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1598 "add_obj_bytes=" SIZE_FORMAT,
1599 add_obj_count, add_obj_size * HeapWordSize);
1600 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1601 "mark_bitmap_bytes=" SIZE_FORMAT,
1602 mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1603 }
1604 #endif // #ifdef ASSERT
1605
1606 // Quick summarization of each space into itself, to see how much is live.
1607 summarize_spaces_quick();
1608
1609 log_develop_trace(gc, compaction)("summary phase: after summarizing each space to self");
1610 NOT_PRODUCT(print_region_ranges());
1611 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1612
1613 // The amount of live data that will end up in old space (assuming it fits).
1614 size_t old_space_total_live = 0;
1615 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1616 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1617 _space_info[id].space()->bottom());
1618 }
1619
1620 MutableSpace* const old_space = _space_info[old_space_id].space();
1621 const size_t old_capacity = old_space->capacity_in_words();
1622 if (old_space_total_live > old_capacity) {
1623 // XXX - should also try to expand
1624 maximum_compaction = true;
1625 }
1626
1627 // Old generations.
1628 summarize_space(old_space_id, maximum_compaction);
1629
1630 // Summarize the remaining spaces in the young gen. The initial target space
1631 // is the old gen. If a space does not fit entirely into the target, then the
1632 // remainder is compacted into the space itself and that space becomes the new
1633 // target.
1634 SpaceId dst_space_id = old_space_id;
1635 HeapWord* dst_space_end = old_space->end();
1636 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1637 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1638 const MutableSpace* space = _space_info[id].space();
1639 const size_t live = pointer_delta(_space_info[id].new_top(),
1640 space->bottom());
1641 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1642
1643 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1644 SpaceId(id), space->bottom(), space->top());)
1645 if (live > 0 && live <= available) {
1646 // All the live data will fit.
1647 bool done = _summary_data.summarize(_space_info[id].split_info(),
1648 space->bottom(), space->top(),
1649 NULL,
1650 *new_top_addr, dst_space_end,
1651 new_top_addr);
1652 assert(done, "space must fit into old gen");
1653
1654 // Reset the new_top value for the space.
1655 _space_info[id].set_new_top(space->bottom());
1656 } else if (live > 0) {
1657 // Attempt to fit part of the source space into the target space.
1658 HeapWord* next_src_addr = NULL;
1659 bool done = _summary_data.summarize(_space_info[id].split_info(),
1660 space->bottom(), space->top(),
1661 &next_src_addr,
1662 *new_top_addr, dst_space_end,
1663 new_top_addr);
1664 assert(!done, "space should not fit into old gen");
1665 assert(next_src_addr != NULL, "sanity");
1666
1667 // The source space becomes the new target, so the remainder is compacted
1668 // within the space itself.
1669 dst_space_id = SpaceId(id);
1670 dst_space_end = space->end();
1671 new_top_addr = _space_info[id].new_top_addr();
1672 NOT_PRODUCT(summary_phase_msg(dst_space_id,
1673 space->bottom(), dst_space_end,
1674 SpaceId(id), next_src_addr, space->top());)
1675 done = _summary_data.summarize(_space_info[id].split_info(),
1676 next_src_addr, space->top(),
1677 NULL,
1678 space->bottom(), dst_space_end,
1679 new_top_addr);
1680 assert(done, "space must fit when compacted into itself");
1681 assert(*new_top_addr <= space->top(), "usage should not grow");
1682 }
1683 }
1684
1685 log_develop_trace(gc, compaction)("Summary_phase: after final summarization");
1686 NOT_PRODUCT(print_region_ranges());
1687 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1688 }
1689
1690 // This method should contain all heap-specific policy for invoking a full
1691 // collection. invoke_no_policy() will only attempt to compact the heap; it
1692 // will do nothing further. If we need to bail out for policy reasons, scavenge
1693 // before full gc, or any other specialized behavior, it needs to be added here.
1694 //
1695 // Note that this method should only be called from the vm_thread while at a
1696 // safepoint.
1697 //
1698 // Note that the all_soft_refs_clear flag in the collector policy
1699 // may be true because this method can be called without intervening
1700 // activity. For example when the heap space is tight and full measure
1701 // are being taken to free space.
1702 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1703 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1704 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1705 "should be in vm thread");
1706
1707 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1708 GCCause::Cause gc_cause = heap->gc_cause();
1709 assert(!heap->is_gc_active(), "not reentrant");
1710
1711 PSAdaptiveSizePolicy* policy = heap->size_policy();
1712 IsGCActiveMark mark;
1713
1714 if (ScavengeBeforeFullGC) {
1715 PSScavenge::invoke_no_policy();
1716 }
1717
1718 const bool clear_all_soft_refs =
1719 heap->collector_policy()->should_clear_all_soft_refs();
1720
1721 PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1722 maximum_heap_compaction);
1723 }
1724
1725 // This method contains no policy. You should probably
1726 // be calling invoke() instead.
1727 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1728 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1729 assert(ref_processor() != NULL, "Sanity");
1730
1731 if (GCLocker::check_active_before_gc()) {
1732 return false;
1733 }
1734
1735 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1736
1737 GCIdMark gc_id_mark;
1738 _gc_timer.register_gc_start();
1739 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
1740
1741 TimeStamp marking_start;
1742 TimeStamp compaction_start;
1743 TimeStamp collection_exit;
1744
1745 GCCause::Cause gc_cause = heap->gc_cause();
1746 PSYoungGen* young_gen = heap->young_gen();
1747 PSOldGen* old_gen = heap->old_gen();
1748 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1749
1750 // The scope of casr should end after code that can change
1751 // CollectorPolicy::_should_clear_all_soft_refs.
1752 ClearedAllSoftRefs casr(maximum_heap_compaction,
1753 heap->collector_policy());
1754
1755 if (ZapUnusedHeapArea) {
1756 // Save information needed to minimize mangling
1757 heap->record_gen_tops_before_GC();
1758 }
1759
1760 // Make sure data structures are sane, make the heap parsable, and do other
1761 // miscellaneous bookkeeping.
1762 pre_compact();
1763
1764 PreGCValues pre_gc_values(heap);
1765
1766 // Get the compaction manager reserved for the VM thread.
1767 ParCompactionManager* const vmthread_cm =
1768 ParCompactionManager::manager_array(gc_task_manager()->workers());
1769
1770 {
1771 ResourceMark rm;
1772 HandleMark hm;
1773
1774 // Set the number of GC threads to be used in this collection
1775 gc_task_manager()->set_active_gang();
1776 gc_task_manager()->task_idle_workers();
1777
1778 GCTraceCPUTime tcpu;
1779 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause, true);
1780
1781 heap->pre_full_gc_dump(&_gc_timer);
1782
1783 TraceCollectorStats tcs(counters());
1784 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
1785
1786 if (TraceOldGenTime) accumulated_time()->start();
1787
1788 // Let the size policy know we're starting
1789 size_policy->major_collection_begin();
1790
1791 CodeCache::gc_prologue();
1792
1793 #if defined(COMPILER2) || INCLUDE_JVMCI
1794 DerivedPointerTable::clear();
1795 #endif
1796
1797 ref_processor()->enable_discovery();
1798 ref_processor()->setup_policy(maximum_heap_compaction);
1799
1800 bool marked_for_unloading = false;
1801
1802 marking_start.update();
1803 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer);
1804
1805 bool max_on_system_gc = UseMaximumCompactionOnSystemGC
1806 && GCCause::is_user_requested_gc(gc_cause);
1807 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
1808
1809 #if defined(COMPILER2) || INCLUDE_JVMCI
1810 assert(DerivedPointerTable::is_active(), "Sanity");
1811 DerivedPointerTable::set_active(false);
1812 #endif
1813
1814 // adjust_roots() updates Universe::_intArrayKlassObj which is
1815 // needed by the compaction for filling holes in the dense prefix.
1816 adjust_roots(vmthread_cm);
1817
1818 compaction_start.update();
1819 compact();
1820
1821 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
1822 // done before resizing.
1823 post_compact();
1824
1825 // Let the size policy know we're done
1826 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
1827
1828 if (UseAdaptiveSizePolicy) {
1829 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
1830 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
1831 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
1832
1833 // Don't check if the size_policy is ready here. Let
1834 // the size_policy check that internally.
1835 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
1836 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
1837 // Swap the survivor spaces if from_space is empty. The
1838 // resize_young_gen() called below is normally used after
1839 // a successful young GC and swapping of survivor spaces;
1840 // otherwise, it will fail to resize the young gen with
1841 // the current implementation.
1842 if (young_gen->from_space()->is_empty()) {
1843 young_gen->from_space()->clear(SpaceDecorator::Mangle);
1844 young_gen->swap_spaces();
1845 }
1846
1847 // Calculate optimal free space amounts
1848 assert(young_gen->max_size() >
1849 young_gen->from_space()->capacity_in_bytes() +
1850 young_gen->to_space()->capacity_in_bytes(),
1851 "Sizes of space in young gen are out-of-bounds");
1852
1853 size_t young_live = young_gen->used_in_bytes();
1854 size_t eden_live = young_gen->eden_space()->used_in_bytes();
1855 size_t old_live = old_gen->used_in_bytes();
1856 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
1857 size_t max_old_gen_size = old_gen->max_gen_size();
1858 size_t max_eden_size = young_gen->max_size() -
1859 young_gen->from_space()->capacity_in_bytes() -
1860 young_gen->to_space()->capacity_in_bytes();
1861
1862 // Used for diagnostics
1863 size_policy->clear_generation_free_space_flags();
1864
1865 size_policy->compute_generations_free_space(young_live,
1866 eden_live,
1867 old_live,
1868 cur_eden,
1869 max_old_gen_size,
1870 max_eden_size,
1871 true /* full gc*/);
1872
1873 size_policy->check_gc_overhead_limit(young_live,
1874 eden_live,
1875 max_old_gen_size,
1876 max_eden_size,
1877 true /* full gc*/,
1878 gc_cause,
1879 heap->collector_policy());
1880
1881 size_policy->decay_supplemental_growth(true /* full gc*/);
1882
1883 heap->resize_old_gen(
1884 size_policy->calculated_old_free_size_in_bytes());
1885
1886 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
1887 size_policy->calculated_survivor_size_in_bytes());
1888 }
1889
1890 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
1891 }
1892
1893 if (UsePerfData) {
1894 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
1895 counters->update_counters();
1896 counters->update_old_capacity(old_gen->capacity_in_bytes());
1897 counters->update_young_capacity(young_gen->capacity_in_bytes());
1898 }
1899
1900 heap->resize_all_tlabs();
1901
1902 // Resize the metaspace capacity after a collection
1903 MetaspaceGC::compute_new_size();
1904
1905 if (TraceOldGenTime) {
1906 accumulated_time()->stop();
1907 }
1908
1909 young_gen->print_used_change(pre_gc_values.young_gen_used());
1910 old_gen->print_used_change(pre_gc_values.old_gen_used());
1911 MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used());
1912
1913 // Track memory usage and detect low memory
1914 MemoryService::track_memory_usage();
1915 heap->update_counters();
1916 gc_task_manager()->release_idle_workers();
1917
1918 heap->post_full_gc_dump(&_gc_timer);
1919 }
1920
1921 #ifdef ASSERT
1922 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
1923 ParCompactionManager* const cm =
1924 ParCompactionManager::manager_array(int(i));
1925 assert(cm->marking_stack()->is_empty(), "should be empty");
1926 assert(cm->region_stack()->is_empty(), "Region stack " SIZE_FORMAT " is not empty", i);
1927 }
1928 #endif // ASSERT
1929
1930 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1931 HandleMark hm; // Discard invalid handles created during verification
1932 Universe::verify("After GC");
1933 }
1934
1935 // Re-verify object start arrays
1936 if (VerifyObjectStartArray &&
1937 VerifyAfterGC) {
1938 old_gen->verify_object_start_array();
1939 }
1940
1941 if (ZapUnusedHeapArea) {
1942 old_gen->object_space()->check_mangled_unused_area_complete();
1943 }
1944
1945 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1946
1947 collection_exit.update();
1948
1949 heap->print_heap_after_gc();
1950 heap->trace_heap_after_gc(&_gc_tracer);
1951
1952 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT,
1953 marking_start.ticks(), compaction_start.ticks(),
1954 collection_exit.ticks());
1955 gc_task_manager()->print_task_time_stamps();
1956
1957 #ifdef TRACESPINNING
1958 ParallelTaskTerminator::print_termination_counts();
1959 #endif
1960
1961 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
1962
1963 _gc_timer.register_gc_end();
1964
1965 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
1966 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
1967
1968 return true;
1969 }
1970
1971 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
1972 PSYoungGen* young_gen,
1973 PSOldGen* old_gen) {
1974 MutableSpace* const eden_space = young_gen->eden_space();
1975 assert(!eden_space->is_empty(), "eden must be non-empty");
1976 assert(young_gen->virtual_space()->alignment() ==
1977 old_gen->virtual_space()->alignment(), "alignments do not match");
1978
1979 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
1980 return false;
1981 }
1982
1983 // Both generations must be completely committed.
1984 if (young_gen->virtual_space()->uncommitted_size() != 0) {
1985 return false;
1986 }
1987 if (old_gen->virtual_space()->uncommitted_size() != 0) {
1988 return false;
1989 }
1990
1991 // Figure out how much to take from eden. Include the average amount promoted
1992 // in the total; otherwise the next young gen GC will simply bail out to a
1993 // full GC.
1994 const size_t alignment = old_gen->virtual_space()->alignment();
1995 const size_t eden_used = eden_space->used_in_bytes();
1996 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
1997 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
1998 const size_t eden_capacity = eden_space->capacity_in_bytes();
1999
2000 if (absorb_size >= eden_capacity) {
2001 return false; // Must leave some space in eden.
2002 }
2003
2004 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2005 if (new_young_size < young_gen->min_gen_size()) {
2006 return false; // Respect young gen minimum size.
2007 }
2008
2009 log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K: "
2010 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2011 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2012 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2013 absorb_size / K,
2014 eden_capacity / K, (eden_capacity - absorb_size) / K,
2015 young_gen->from_space()->used_in_bytes() / K,
2016 young_gen->to_space()->used_in_bytes() / K,
2017 young_gen->capacity_in_bytes() / K, new_young_size / K);
2018
2019 // Fill the unused part of the old gen.
2020 MutableSpace* const old_space = old_gen->object_space();
2021 HeapWord* const unused_start = old_space->top();
2022 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2023
2024 if (unused_words > 0) {
2025 if (unused_words < CollectedHeap::min_fill_size()) {
2026 return false; // If the old gen cannot be filled, must give up.
2027 }
2028 CollectedHeap::fill_with_objects(unused_start, unused_words);
2029 }
2030
2031 // Take the live data from eden and set both top and end in the old gen to
2032 // eden top. (Need to set end because reset_after_change() mangles the region
2033 // from end to virtual_space->high() in debug builds).
2034 HeapWord* const new_top = eden_space->top();
2035 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2036 absorb_size);
2037 young_gen->reset_after_change();
2038 old_space->set_top(new_top);
2039 old_space->set_end(new_top);
2040 old_gen->reset_after_change();
2041
2042 // Update the object start array for the filler object and the data from eden.
2043 ObjectStartArray* const start_array = old_gen->start_array();
2044 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2045 start_array->allocate_block(p);
2046 }
2047
2048 // Could update the promoted average here, but it is not typically updated at
2049 // full GCs and the value to use is unclear. Something like
2050 //
2051 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2052
2053 size_policy->set_bytes_absorbed_from_eden(absorb_size);
2054 return true;
2055 }
2056
2057 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2058 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2059 "shouldn't return NULL");
2060 return ParallelScavengeHeap::gc_task_manager();
2061 }
2062
2063 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2064 bool maximum_heap_compaction,
2065 ParallelOldTracer *gc_tracer) {
2066 // Recursively traverse all live objects and mark them
2067 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer);
2068
2069 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2070 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2071 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2072 TaskQueueSetSuper* qset = ParCompactionManager::stack_array();
2073 ParallelTaskTerminator terminator(active_gc_threads, qset);
2074
2075 ParCompactionManager::MarkAndPushClosure mark_and_push_closure(cm);
2076 ParCompactionManager::FollowStackClosure follow_stack_closure(cm);
2077
2078 // Need new claim bits before marking starts.
2079 ClassLoaderDataGraph::clear_claimed_marks();
2080
2081 {
2082 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer);
2083
2084 ParallelScavengeHeap::ParStrongRootsScope psrs;
2085
2086 GCTaskQueue* q = GCTaskQueue::create();
2087
2088 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2089 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2090 // We scan the thread roots in parallel
2091 Threads::create_thread_roots_marking_tasks(q);
2092 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2093 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
2094 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2095 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2096 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data));
2097 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2098 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2099
2100 if (active_gc_threads > 1) {
2101 for (uint j = 0; j < active_gc_threads; j++) {
2102 q->enqueue(new StealMarkingTask(&terminator));
2103 }
2104 }
2105
2106 gc_task_manager()->execute_and_wait(q);
2107 }
2108
2109 // Process reference objects found during marking
2110 {
2111 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
2112
2113 ReferenceProcessorStats stats;
2114 if (ref_processor()->processing_is_mt()) {
2115 RefProcTaskExecutor task_executor;
2116 stats = ref_processor()->process_discovered_references(
2117 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2118 &task_executor, &_gc_timer);
2119 } else {
2120 stats = ref_processor()->process_discovered_references(
2121 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
2122 &_gc_timer);
2123 }
2124
2125 gc_tracer->report_gc_reference_stats(stats);
2126 }
2127
2128 // This is the point where the entire marking should have completed.
2129 assert(cm->marking_stacks_empty(), "Marking should have completed");
2130
2131 {
2132 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer);
2133
2134 // Follow system dictionary roots and unload classes.
2135 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
2136
2137 // Unload nmethods.
2138 CodeCache::do_unloading(is_alive_closure(), purged_class);
2139
2140 // Prune dead klasses from subklass/sibling/implementor lists.
2141 Klass::clean_weak_klass_links(is_alive_closure());
2142 }
2143
2144 {
2145 GCTraceTime(Debug, gc, phases) t("Scrub String Table", &_gc_timer);
2146 // Delete entries for dead interned strings.
2147 StringTable::unlink(is_alive_closure());
2148 }
2149
2150 {
2151 GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", &_gc_timer);
2152 // Clean up unreferenced symbols in symbol table.
2153 SymbolTable::unlink();
2154 }
2155
2156 _gc_tracer.report_object_count_after_gc(is_alive_closure());
2157 }
2158
2159 void PSParallelCompact::adjust_roots(ParCompactionManager* cm) {
2160 // Adjust the pointers to reflect the new locations
2161 GCTraceTime(Info, gc, phases) tm("Adjust Roots", &_gc_timer);
2162
2163 // Need new claim bits when tracing through and adjusting pointers.
2164 ClassLoaderDataGraph::clear_claimed_marks();
2165
2166 PSParallelCompact::AdjustPointerClosure oop_closure(cm);
2167 PSParallelCompact::AdjustKlassClosure klass_closure(cm);
2168
2169 // General strong roots.
2170 Universe::oops_do(&oop_closure);
2171 JNIHandles::oops_do(&oop_closure); // Global (strong) JNI handles
2172 Threads::oops_do(&oop_closure, NULL);
2173 ObjectSynchronizer::oops_do(&oop_closure);
2174 FlatProfiler::oops_do(&oop_closure);
2175 Management::oops_do(&oop_closure);
2176 JvmtiExport::oops_do(&oop_closure);
2177 SystemDictionary::oops_do(&oop_closure);
2178 ClassLoaderDataGraph::oops_do(&oop_closure, &klass_closure, true);
2179
2180 // Now adjust pointers in remaining weak roots. (All of which should
2181 // have been cleared if they pointed to non-surviving objects.)
2182 // Global (weak) JNI handles
2183 JNIHandles::weak_oops_do(&oop_closure);
2184
2185 CodeBlobToOopClosure adjust_from_blobs(&oop_closure, CodeBlobToOopClosure::FixRelocations);
2186 CodeCache::blobs_do(&adjust_from_blobs);
2187 AOTLoader::oops_do(&oop_closure);
2188 StringTable::oops_do(&oop_closure);
2189 ref_processor()->weak_oops_do(&oop_closure);
2190 // Roots were visited so references into the young gen in roots
2191 // may have been scanned. Process them also.
2192 // Should the reference processor have a span that excludes
2193 // young gen objects?
2194 PSScavenge::reference_processor()->weak_oops_do(&oop_closure);
2195 }
2196
2197 // Helper class to print 8 region numbers per line and then print the total at the end.
2198 class FillableRegionLogger : public StackObj {
2199 private:
2200 Log(gc, compaction) log;
2201 static const int LineLength = 8;
2202 size_t _regions[LineLength];
2203 int _next_index;
2204 bool _enabled;
2205 size_t _total_regions;
2206 public:
2207 FillableRegionLogger() : _next_index(0), _total_regions(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)) { }
2208 ~FillableRegionLogger() {
2209 log.trace(SIZE_FORMAT " initially fillable regions", _total_regions);
2210 }
2211
2212 void print_line() {
2213 if (!_enabled || _next_index == 0) {
2214 return;
2215 }
2216 FormatBuffer<> line("Fillable: ");
2217 for (int i = 0; i < _next_index; i++) {
2218 line.append(" " SIZE_FORMAT_W(7), _regions[i]);
2219 }
2220 log.trace("%s", line.buffer());
2221 _next_index = 0;
2222 }
2223
2224 void handle(size_t region) {
2225 if (!_enabled) {
2226 return;
2227 }
2228 _regions[_next_index++] = region;
2229 if (_next_index == LineLength) {
2230 print_line();
2231 }
2232 _total_regions++;
2233 }
2234 };
2235
2236 void PSParallelCompact::prepare_region_draining_tasks(GCTaskQueue* q,
2237 uint parallel_gc_threads)
2238 {
2239 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer);
2240
2241 // Find the threads that are active
2242 unsigned int which = 0;
2243
2244 // Find all regions that are available (can be filled immediately) and
2245 // distribute them to the thread stacks. The iteration is done in reverse
2246 // order (high to low) so the regions will be removed in ascending order.
2247
2248 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2249
2250 which = 0;
2251 // id + 1 is used to test termination so unsigned can
2252 // be used with an old_space_id == 0.
2253 FillableRegionLogger region_logger;
2254 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2255 SpaceInfo* const space_info = _space_info + id;
2256 MutableSpace* const space = space_info->space();
2257 HeapWord* const new_top = space_info->new_top();
2258
2259 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2260 const size_t end_region =
2261 sd.addr_to_region_idx(sd.region_align_up(new_top));
2262
2263 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2264 if (sd.region(cur)->claim_unsafe()) {
2265 ParCompactionManager* cm = ParCompactionManager::manager_array(which);
2266 cm->region_stack()->push(cur);
2267 region_logger.handle(cur);
2268 // Assign regions to tasks in round-robin fashion.
2269 if (++which == parallel_gc_threads) {
2270 which = 0;
2271 }
2272 }
2273 }
2274 region_logger.print_line();
2275 }
2276 }
2277
2278 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2279
2280 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2281 uint parallel_gc_threads) {
2282 GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer);
2283
2284 ParallelCompactData& sd = PSParallelCompact::summary_data();
2285
2286 // Iterate over all the spaces adding tasks for updating
2287 // regions in the dense prefix. Assume that 1 gc thread
2288 // will work on opening the gaps and the remaining gc threads
2289 // will work on the dense prefix.
2290 unsigned int space_id;
2291 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2292 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2293 const MutableSpace* const space = _space_info[space_id].space();
2294
2295 if (dense_prefix_end == space->bottom()) {
2296 // There is no dense prefix for this space.
2297 continue;
2298 }
2299
2300 // The dense prefix is before this region.
2301 size_t region_index_end_dense_prefix =
2302 sd.addr_to_region_idx(dense_prefix_end);
2303 RegionData* const dense_prefix_cp =
2304 sd.region(region_index_end_dense_prefix);
2305 assert(dense_prefix_end == space->end() ||
2306 dense_prefix_cp->available() ||
2307 dense_prefix_cp->claimed(),
2308 "The region after the dense prefix should always be ready to fill");
2309
2310 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2311
2312 // Is there dense prefix work?
2313 size_t total_dense_prefix_regions =
2314 region_index_end_dense_prefix - region_index_start;
2315 // How many regions of the dense prefix should be given to
2316 // each thread?
2317 if (total_dense_prefix_regions > 0) {
2318 uint tasks_for_dense_prefix = 1;
2319 if (total_dense_prefix_regions <=
2320 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2321 // Don't over partition. This assumes that
2322 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2323 // so there are not many regions to process.
2324 tasks_for_dense_prefix = parallel_gc_threads;
2325 } else {
2326 // Over partition
2327 tasks_for_dense_prefix = parallel_gc_threads *
2328 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2329 }
2330 size_t regions_per_thread = total_dense_prefix_regions /
2331 tasks_for_dense_prefix;
2332 // Give each thread at least 1 region.
2333 if (regions_per_thread == 0) {
2334 regions_per_thread = 1;
2335 }
2336
2337 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2338 if (region_index_start >= region_index_end_dense_prefix) {
2339 break;
2340 }
2341 // region_index_end is not processed
2342 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2343 region_index_end_dense_prefix);
2344 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2345 region_index_start,
2346 region_index_end));
2347 region_index_start = region_index_end;
2348 }
2349 }
2350 // This gets any part of the dense prefix that did not
2351 // fit evenly.
2352 if (region_index_start < region_index_end_dense_prefix) {
2353 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2354 region_index_start,
2355 region_index_end_dense_prefix));
2356 }
2357 }
2358 }
2359
2360 void PSParallelCompact::enqueue_region_stealing_tasks(
2361 GCTaskQueue* q,
2362 ParallelTaskTerminator* terminator_ptr,
2363 uint parallel_gc_threads) {
2364 GCTraceTime(Trace, gc, phases) tm("Steal Task Setup", &_gc_timer);
2365
2366 // Once a thread has drained it's stack, it should try to steal regions from
2367 // other threads.
2368 for (uint j = 0; j < parallel_gc_threads; j++) {
2369 q->enqueue(new CompactionWithStealingTask(terminator_ptr));
2370 }
2371 }
2372
2373 #ifdef ASSERT
2374 // Write a histogram of the number of times the block table was filled for a
2375 // region.
2376 void PSParallelCompact::write_block_fill_histogram()
2377 {
2378 if (!log_develop_is_enabled(Trace, gc, compaction)) {
2379 return;
2380 }
2381
2382 Log(gc, compaction) log;
2383 ResourceMark rm;
2384 outputStream* out = log.trace_stream();
2385
2386 typedef ParallelCompactData::RegionData rd_t;
2387 ParallelCompactData& sd = summary_data();
2388
2389 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2390 MutableSpace* const spc = _space_info[id].space();
2391 if (spc->bottom() != spc->top()) {
2392 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
2393 HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
2394 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
2395
2396 size_t histo[5] = { 0, 0, 0, 0, 0 };
2397 const size_t histo_len = sizeof(histo) / sizeof(size_t);
2398 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
2399
2400 for (const rd_t* cur = beg; cur < end; ++cur) {
2401 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
2402 }
2403 out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
2404 for (size_t i = 0; i < histo_len; ++i) {
2405 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
2406 histo[i], 100.0 * histo[i] / region_cnt);
2407 }
2408 out->cr();
2409 }
2410 }
2411 }
2412 #endif // #ifdef ASSERT
2413
2414 void PSParallelCompact::compact() {
2415 GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer);
2416
2417 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2418 PSOldGen* old_gen = heap->old_gen();
2419 old_gen->start_array()->reset();
2420 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2421 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2422 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2423 ParallelTaskTerminator terminator(active_gc_threads, qset);
2424
2425 GCTaskQueue* q = GCTaskQueue::create();
2426 prepare_region_draining_tasks(q, active_gc_threads);
2427 enqueue_dense_prefix_tasks(q, active_gc_threads);
2428 enqueue_region_stealing_tasks(q, &terminator, active_gc_threads);
2429
2430 {
2431 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer);
2432
2433 gc_task_manager()->execute_and_wait(q);
2434
2435 #ifdef ASSERT
2436 // Verify that all regions have been processed before the deferred updates.
2437 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2438 verify_complete(SpaceId(id));
2439 }
2440 #endif
2441 }
2442
2443 {
2444 // Update the deferred objects, if any. Any compaction manager can be used.
2445 GCTraceTime(Trace, gc, phases) tm("Deferred Updates", &_gc_timer);
2446 ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2447 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2448 update_deferred_objects(cm, SpaceId(id));
2449 }
2450 }
2451
2452 DEBUG_ONLY(write_block_fill_histogram());
2453 }
2454
2455 #ifdef ASSERT
2456 void PSParallelCompact::verify_complete(SpaceId space_id) {
2457 // All Regions between space bottom() to new_top() should be marked as filled
2458 // and all Regions between new_top() and top() should be available (i.e.,
2459 // should have been emptied).
2460 ParallelCompactData& sd = summary_data();
2461 SpaceInfo si = _space_info[space_id];
2462 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2463 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2464 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2465 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2466 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2467
2468 bool issued_a_warning = false;
2469
2470 size_t cur_region;
2471 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2472 const RegionData* const c = sd.region(cur_region);
2473 if (!c->completed()) {
2474 log_warning(gc)("region " SIZE_FORMAT " not filled: destination_count=%u",
2475 cur_region, c->destination_count());
2476 issued_a_warning = true;
2477 }
2478 }
2479
2480 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2481 const RegionData* const c = sd.region(cur_region);
2482 if (!c->available()) {
2483 log_warning(gc)("region " SIZE_FORMAT " not empty: destination_count=%u",
2484 cur_region, c->destination_count());
2485 issued_a_warning = true;
2486 }
2487 }
2488
2489 if (issued_a_warning) {
2490 print_region_ranges();
2491 }
2492 }
2493 #endif // #ifdef ASSERT
2494
2495 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) {
2496 _start_array->allocate_block(addr);
2497 compaction_manager()->update_contents(oop(addr));
2498 }
2499
2500 // Update interior oops in the ranges of regions [beg_region, end_region).
2501 void
2502 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2503 SpaceId space_id,
2504 size_t beg_region,
2505 size_t end_region) {
2506 ParallelCompactData& sd = summary_data();
2507 ParMarkBitMap* const mbm = mark_bitmap();
2508
2509 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2510 HeapWord* const end_addr = sd.region_to_addr(end_region);
2511 assert(beg_region <= end_region, "bad region range");
2512 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2513
2514 #ifdef ASSERT
2515 // Claim the regions to avoid triggering an assert when they are marked as
2516 // filled.
2517 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2518 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2519 }
2520 #endif // #ifdef ASSERT
2521
2522 if (beg_addr != space(space_id)->bottom()) {
2523 // Find the first live object or block of dead space that *starts* in this
2524 // range of regions. If a partial object crosses onto the region, skip it;
2525 // it will be marked for 'deferred update' when the object head is
2526 // processed. If dead space crosses onto the region, it is also skipped; it
2527 // will be filled when the prior region is processed. If neither of those
2528 // apply, the first word in the region is the start of a live object or dead
2529 // space.
2530 assert(beg_addr > space(space_id)->bottom(), "sanity");
2531 const RegionData* const cp = sd.region(beg_region);
2532 if (cp->partial_obj_size() != 0) {
2533 beg_addr = sd.partial_obj_end(beg_region);
2534 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2535 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2536 }
2537 }
2538
2539 if (beg_addr < end_addr) {
2540 // A live object or block of dead space starts in this range of Regions.
2541 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2542
2543 // Create closures and iterate.
2544 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2545 FillClosure fill_closure(cm, space_id);
2546 ParMarkBitMap::IterationStatus status;
2547 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2548 dense_prefix_end);
2549 if (status == ParMarkBitMap::incomplete) {
2550 update_closure.do_addr(update_closure.source());
2551 }
2552 }
2553
2554 // Mark the regions as filled.
2555 RegionData* const beg_cp = sd.region(beg_region);
2556 RegionData* const end_cp = sd.region(end_region);
2557 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2558 cp->set_completed();
2559 }
2560 }
2561
2562 // Return the SpaceId for the space containing addr. If addr is not in the
2563 // heap, last_space_id is returned. In debug mode it expects the address to be
2564 // in the heap and asserts such.
2565 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2566 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
2567
2568 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2569 if (_space_info[id].space()->contains(addr)) {
2570 return SpaceId(id);
2571 }
2572 }
2573
2574 assert(false, "no space contains the addr");
2575 return last_space_id;
2576 }
2577
2578 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2579 SpaceId id) {
2580 assert(id < last_space_id, "bad space id");
2581
2582 ParallelCompactData& sd = summary_data();
2583 const SpaceInfo* const space_info = _space_info + id;
2584 ObjectStartArray* const start_array = space_info->start_array();
2585
2586 const MutableSpace* const space = space_info->space();
2587 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2588 HeapWord* const beg_addr = space_info->dense_prefix();
2589 HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2590
2591 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2592 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2593 const RegionData* cur_region;
2594 for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2595 HeapWord* const addr = cur_region->deferred_obj_addr();
2596 if (addr != NULL) {
2597 if (start_array != NULL) {
2598 start_array->allocate_block(addr);
2599 }
2600 cm->update_contents(oop(addr));
2601 assert(oop(addr)->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(addr)));
2602 }
2603 }
2604 }
2605
2606 // Skip over count live words starting from beg, and return the address of the
2607 // next live word. Unless marked, the word corresponding to beg is assumed to
2608 // be dead. Callers must either ensure beg does not correspond to the middle of
2609 // an object, or account for those live words in some other way. Callers must
2610 // also ensure that there are enough live words in the range [beg, end) to skip.
2611 HeapWord*
2612 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2613 {
2614 assert(count > 0, "sanity");
2615
2616 ParMarkBitMap* m = mark_bitmap();
2617 idx_t bits_to_skip = m->words_to_bits(count);
2618 idx_t cur_beg = m->addr_to_bit(beg);
2619 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
2620
2621 do {
2622 cur_beg = m->find_obj_beg(cur_beg, search_end);
2623 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2624 const size_t obj_bits = cur_end - cur_beg + 1;
2625 if (obj_bits > bits_to_skip) {
2626 return m->bit_to_addr(cur_beg + bits_to_skip);
2627 }
2628 bits_to_skip -= obj_bits;
2629 cur_beg = cur_end + 1;
2630 } while (bits_to_skip > 0);
2631
2632 // Skipping the desired number of words landed just past the end of an object.
2633 // Find the start of the next object.
2634 cur_beg = m->find_obj_beg(cur_beg, search_end);
2635 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2636 return m->bit_to_addr(cur_beg);
2637 }
2638
2639 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2640 SpaceId src_space_id,
2641 size_t src_region_idx)
2642 {
2643 assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2644
2645 const SplitInfo& split_info = _space_info[src_space_id].split_info();
2646 if (split_info.dest_region_addr() == dest_addr) {
2647 // The partial object ending at the split point contains the first word to
2648 // be copied to dest_addr.
2649 return split_info.first_src_addr();
2650 }
2651
2652 const ParallelCompactData& sd = summary_data();
2653 ParMarkBitMap* const bitmap = mark_bitmap();
2654 const size_t RegionSize = ParallelCompactData::RegionSize;
2655
2656 assert(sd.is_region_aligned(dest_addr), "not aligned");
2657 const RegionData* const src_region_ptr = sd.region(src_region_idx);
2658 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2659 HeapWord* const src_region_destination = src_region_ptr->destination();
2660
2661 assert(dest_addr >= src_region_destination, "wrong src region");
2662 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2663
2664 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2665 HeapWord* const src_region_end = src_region_beg + RegionSize;
2666
2667 HeapWord* addr = src_region_beg;
2668 if (dest_addr == src_region_destination) {
2669 // Return the first live word in the source region.
2670 if (partial_obj_size == 0) {
2671 addr = bitmap->find_obj_beg(addr, src_region_end);
2672 assert(addr < src_region_end, "no objects start in src region");
2673 }
2674 return addr;
2675 }
2676
2677 // Must skip some live data.
2678 size_t words_to_skip = dest_addr - src_region_destination;
2679 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2680
2681 if (partial_obj_size >= words_to_skip) {
2682 // All the live words to skip are part of the partial object.
2683 addr += words_to_skip;
2684 if (partial_obj_size == words_to_skip) {
2685 // Find the first live word past the partial object.
2686 addr = bitmap->find_obj_beg(addr, src_region_end);
2687 assert(addr < src_region_end, "wrong src region");
2688 }
2689 return addr;
2690 }
2691
2692 // Skip over the partial object (if any).
2693 if (partial_obj_size != 0) {
2694 words_to_skip -= partial_obj_size;
2695 addr += partial_obj_size;
2696 }
2697
2698 // Skip over live words due to objects that start in the region.
2699 addr = skip_live_words(addr, src_region_end, words_to_skip);
2700 assert(addr < src_region_end, "wrong src region");
2701 return addr;
2702 }
2703
2704 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2705 SpaceId src_space_id,
2706 size_t beg_region,
2707 HeapWord* end_addr)
2708 {
2709 ParallelCompactData& sd = summary_data();
2710
2711 #ifdef ASSERT
2712 MutableSpace* const src_space = _space_info[src_space_id].space();
2713 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2714 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2715 "src_space_id does not match beg_addr");
2716 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2717 "src_space_id does not match end_addr");
2718 #endif // #ifdef ASSERT
2719
2720 RegionData* const beg = sd.region(beg_region);
2721 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2722
2723 // Regions up to new_top() are enqueued if they become available.
2724 HeapWord* const new_top = _space_info[src_space_id].new_top();
2725 RegionData* const enqueue_end =
2726 sd.addr_to_region_ptr(sd.region_align_up(new_top));
2727
2728 for (RegionData* cur = beg; cur < end; ++cur) {
2729 assert(cur->data_size() > 0, "region must have live data");
2730 cur->decrement_destination_count();
2731 if (cur < enqueue_end && cur->available() && cur->claim()) {
2732 cm->push_region(sd.region(cur));
2733 }
2734 }
2735 }
2736
2737 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2738 SpaceId& src_space_id,
2739 HeapWord*& src_space_top,
2740 HeapWord* end_addr)
2741 {
2742 typedef ParallelCompactData::RegionData RegionData;
2743
2744 ParallelCompactData& sd = PSParallelCompact::summary_data();
2745 const size_t region_size = ParallelCompactData::RegionSize;
2746
2747 size_t src_region_idx = 0;
2748
2749 // Skip empty regions (if any) up to the top of the space.
2750 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2751 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2752 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2753 const RegionData* const top_region_ptr =
2754 sd.addr_to_region_ptr(top_aligned_up);
2755 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2756 ++src_region_ptr;
2757 }
2758
2759 if (src_region_ptr < top_region_ptr) {
2760 // The next source region is in the current space. Update src_region_idx
2761 // and the source address to match src_region_ptr.
2762 src_region_idx = sd.region(src_region_ptr);
2763 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
2764 if (src_region_addr > closure.source()) {
2765 closure.set_source(src_region_addr);
2766 }
2767 return src_region_idx;
2768 }
2769
2770 // Switch to a new source space and find the first non-empty region.
2771 unsigned int space_id = src_space_id + 1;
2772 assert(space_id < last_space_id, "not enough spaces");
2773
2774 HeapWord* const destination = closure.destination();
2775
2776 do {
2777 MutableSpace* space = _space_info[space_id].space();
2778 HeapWord* const bottom = space->bottom();
2779 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
2780
2781 // Iterate over the spaces that do not compact into themselves.
2782 if (bottom_cp->destination() != bottom) {
2783 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
2784 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
2785
2786 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
2787 if (src_cp->live_obj_size() > 0) {
2788 // Found it.
2789 assert(src_cp->destination() == destination,
2790 "first live obj in the space must match the destination");
2791 assert(src_cp->partial_obj_size() == 0,
2792 "a space cannot begin with a partial obj");
2793
2794 src_space_id = SpaceId(space_id);
2795 src_space_top = space->top();
2796 const size_t src_region_idx = sd.region(src_cp);
2797 closure.set_source(sd.region_to_addr(src_region_idx));
2798 return src_region_idx;
2799 } else {
2800 assert(src_cp->data_size() == 0, "sanity");
2801 }
2802 }
2803 }
2804 } while (++space_id < last_space_id);
2805
2806 assert(false, "no source region was found");
2807 return 0;
2808 }
2809
2810 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
2811 {
2812 typedef ParMarkBitMap::IterationStatus IterationStatus;
2813 const size_t RegionSize = ParallelCompactData::RegionSize;
2814 ParMarkBitMap* const bitmap = mark_bitmap();
2815 ParallelCompactData& sd = summary_data();
2816 RegionData* const region_ptr = sd.region(region_idx);
2817
2818 // Get the items needed to construct the closure.
2819 HeapWord* dest_addr = sd.region_to_addr(region_idx);
2820 SpaceId dest_space_id = space_id(dest_addr);
2821 ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
2822 HeapWord* new_top = _space_info[dest_space_id].new_top();
2823 assert(dest_addr < new_top, "sanity");
2824 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
2825
2826 // Get the source region and related info.
2827 size_t src_region_idx = region_ptr->source_region();
2828 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2829 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2830
2831 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
2832 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2833
2834 // Adjust src_region_idx to prepare for decrementing destination counts (the
2835 // destination count is not decremented when a region is copied to itself).
2836 if (src_region_idx == region_idx) {
2837 src_region_idx += 1;
2838 }
2839
2840 if (bitmap->is_unmarked(closure.source())) {
2841 // The first source word is in the middle of an object; copy the remainder
2842 // of the object or as much as will fit. The fact that pointer updates were
2843 // deferred will be noted when the object header is processed.
2844 HeapWord* const old_src_addr = closure.source();
2845 closure.copy_partial_obj();
2846 if (closure.is_full()) {
2847 decrement_destination_counts(cm, src_space_id, src_region_idx,
2848 closure.source());
2849 region_ptr->set_deferred_obj_addr(NULL);
2850 region_ptr->set_completed();
2851 return;
2852 }
2853
2854 HeapWord* const end_addr = sd.region_align_down(closure.source());
2855 if (sd.region_align_down(old_src_addr) != end_addr) {
2856 // The partial object was copied from more than one source region.
2857 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2858
2859 // Move to the next source region, possibly switching spaces as well. All
2860 // args except end_addr may be modified.
2861 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2862 end_addr);
2863 }
2864 }
2865
2866 do {
2867 HeapWord* const cur_addr = closure.source();
2868 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2869 src_space_top);
2870 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
2871
2872 if (status == ParMarkBitMap::incomplete) {
2873 // The last obj that starts in the source region does not end in the
2874 // region.
2875 assert(closure.source() < end_addr, "sanity");
2876 HeapWord* const obj_beg = closure.source();
2877 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
2878 src_space_top);
2879 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
2880 if (obj_end < range_end) {
2881 // The end was found; the entire object will fit.
2882 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
2883 assert(status != ParMarkBitMap::would_overflow, "sanity");
2884 } else {
2885 // The end was not found; the object will not fit.
2886 assert(range_end < src_space_top, "obj cannot cross space boundary");
2887 status = ParMarkBitMap::would_overflow;
2888 }
2889 }
2890
2891 if (status == ParMarkBitMap::would_overflow) {
2892 // The last object did not fit. Note that interior oop updates were
2893 // deferred, then copy enough of the object to fill the region.
2894 region_ptr->set_deferred_obj_addr(closure.destination());
2895 status = closure.copy_until_full(); // copies from closure.source()
2896
2897 decrement_destination_counts(cm, src_space_id, src_region_idx,
2898 closure.source());
2899 region_ptr->set_completed();
2900 return;
2901 }
2902
2903 if (status == ParMarkBitMap::full) {
2904 decrement_destination_counts(cm, src_space_id, src_region_idx,
2905 closure.source());
2906 region_ptr->set_deferred_obj_addr(NULL);
2907 region_ptr->set_completed();
2908 return;
2909 }
2910
2911 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2912
2913 // Move to the next source region, possibly switching spaces as well. All
2914 // args except end_addr may be modified.
2915 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2916 end_addr);
2917 } while (true);
2918 }
2919
2920 void PSParallelCompact::fill_blocks(size_t region_idx)
2921 {
2922 // Fill in the block table elements for the specified region. Each block
2923 // table element holds the number of live words in the region that are to the
2924 // left of the first object that starts in the block. Thus only blocks in
2925 // which an object starts need to be filled.
2926 //
2927 // The algorithm scans the section of the bitmap that corresponds to the
2928 // region, keeping a running total of the live words. When an object start is
2929 // found, if it's the first to start in the block that contains it, the
2930 // current total is written to the block table element.
2931 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
2932 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
2933 const size_t RegionSize = ParallelCompactData::RegionSize;
2934
2935 ParallelCompactData& sd = summary_data();
2936 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
2937 if (partial_obj_size >= RegionSize) {
2938 return; // No objects start in this region.
2939 }
2940
2941 // Ensure the first loop iteration decides that the block has changed.
2942 size_t cur_block = sd.block_count();
2943
2944 const ParMarkBitMap* const bitmap = mark_bitmap();
2945
2946 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
2947 assert((size_t)1 << Log2BitsPerBlock ==
2948 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
2949
2950 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
2951 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
2952 size_t live_bits = bitmap->words_to_bits(partial_obj_size);
2953 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
2954 while (beg_bit < range_end) {
2955 const size_t new_block = beg_bit >> Log2BitsPerBlock;
2956 if (new_block != cur_block) {
2957 cur_block = new_block;
2958 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
2959 }
2960
2961 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
2962 if (end_bit < range_end - 1) {
2963 live_bits += end_bit - beg_bit + 1;
2964 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
2965 } else {
2966 return;
2967 }
2968 }
2969 }
2970
2971 void
2972 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
2973 const MutableSpace* sp = space(space_id);
2974 if (sp->is_empty()) {
2975 return;
2976 }
2977
2978 ParallelCompactData& sd = PSParallelCompact::summary_data();
2979 ParMarkBitMap* const bitmap = mark_bitmap();
2980 HeapWord* const dp_addr = dense_prefix(space_id);
2981 HeapWord* beg_addr = sp->bottom();
2982 HeapWord* end_addr = sp->top();
2983
2984 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
2985
2986 const size_t beg_region = sd.addr_to_region_idx(beg_addr);
2987 const size_t dp_region = sd.addr_to_region_idx(dp_addr);
2988 if (beg_region < dp_region) {
2989 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
2990 }
2991
2992 // The destination of the first live object that starts in the region is one
2993 // past the end of the partial object entering the region (if any).
2994 HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
2995 HeapWord* const new_top = _space_info[space_id].new_top();
2996 assert(new_top >= dest_addr, "bad new_top value");
2997 const size_t words = pointer_delta(new_top, dest_addr);
2998
2999 if (words > 0) {
3000 ObjectStartArray* start_array = _space_info[space_id].start_array();
3001 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3002
3003 ParMarkBitMap::IterationStatus status;
3004 status = bitmap->iterate(&closure, dest_addr, end_addr);
3005 assert(status == ParMarkBitMap::full, "iteration not complete");
3006 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3007 "live objects skipped because closure is full");
3008 }
3009 }
3010
3011 jlong PSParallelCompact::millis_since_last_gc() {
3012 // We need a monotonically non-decreasing time in ms but
3013 // os::javaTimeMillis() does not guarantee monotonicity.
3014 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3015 jlong ret_val = now - _time_of_last_gc;
3016 // XXX See note in genCollectedHeap::millis_since_last_gc().
3017 if (ret_val < 0) {
3018 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);)
3019 return 0;
3020 }
3021 return ret_val;
3022 }
3023
3024 void PSParallelCompact::reset_millis_since_last_gc() {
3025 // We need a monotonically non-decreasing time in ms but
3026 // os::javaTimeMillis() does not guarantee monotonicity.
3027 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3028 }
3029
3030 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3031 {
3032 if (source() != destination()) {
3033 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3034 Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3035 }
3036 update_state(words_remaining());
3037 assert(is_full(), "sanity");
3038 return ParMarkBitMap::full;
3039 }
3040
3041 void MoveAndUpdateClosure::copy_partial_obj()
3042 {
3043 size_t words = words_remaining();
3044
3045 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3046 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3047 if (end_addr < range_end) {
3048 words = bitmap()->obj_size(source(), end_addr);
3049 }
3050
3051 // This test is necessary; if omitted, the pointer updates to a partial object
3052 // that crosses the dense prefix boundary could be overwritten.
3053 if (source() != destination()) {
3054 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3055 Copy::aligned_conjoint_words(source(), destination(), words);
3056 }
3057 update_state(words);
3058 }
3059
3060 void InstanceKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3061 PSParallelCompact::AdjustPointerClosure closure(cm);
3062 oop_oop_iterate_oop_maps<true>(obj, &closure);
3063 }
3064
3065 void InstanceMirrorKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3066 InstanceKlass::oop_pc_update_pointers(obj, cm);
3067
3068 PSParallelCompact::AdjustPointerClosure closure(cm);
3069 oop_oop_iterate_statics<true>(obj, &closure);
3070 }
3071
3072 void InstanceClassLoaderKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3073 InstanceKlass::oop_pc_update_pointers(obj, cm);
3074 }
3075
3076 #ifdef ASSERT
3077 template <class T> static void trace_reference_gc(const char *s, oop obj,
3078 T* referent_addr,
3079 T* next_addr,
3080 T* discovered_addr) {
3081 log_develop_trace(gc, ref)("%s obj " PTR_FORMAT, s, p2i(obj));
3082 log_develop_trace(gc, ref)(" referent_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3083 p2i(referent_addr), referent_addr ? p2i(oopDesc::load_decode_heap_oop(referent_addr)) : NULL);
3084 log_develop_trace(gc, ref)(" next_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3085 p2i(next_addr), next_addr ? p2i(oopDesc::load_decode_heap_oop(next_addr)) : NULL);
3086 log_develop_trace(gc, ref)(" discovered_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3087 p2i(discovered_addr), discovered_addr ? p2i(oopDesc::load_decode_heap_oop(discovered_addr)) : NULL);
3088 }
3089 #endif
3090
3091 template <class T>
3092 static void oop_pc_update_pointers_specialized(oop obj, ParCompactionManager* cm) {
3093 T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj);
3094 PSParallelCompact::adjust_pointer(referent_addr, cm);
3095 T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj);
3096 PSParallelCompact::adjust_pointer(next_addr, cm);
3097 T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj);
3098 PSParallelCompact::adjust_pointer(discovered_addr, cm);
3099 debug_only(trace_reference_gc("InstanceRefKlass::oop_update_ptrs", obj,
3100 referent_addr, next_addr, discovered_addr);)
3101 }
3102
3103 void InstanceRefKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3104 InstanceKlass::oop_pc_update_pointers(obj, cm);
3105
3106 if (UseCompressedOops) {
3107 oop_pc_update_pointers_specialized<narrowOop>(obj, cm);
3108 } else {
3109 oop_pc_update_pointers_specialized<oop>(obj, cm);
3110 }
3111 }
3112
3113 void ObjArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3114 assert(obj->is_objArray(), "obj must be obj array");
3115 PSParallelCompact::AdjustPointerClosure closure(cm);
3116 oop_oop_iterate_elements<true>(objArrayOop(obj), &closure);
3117 }
3118
3119 void TypeArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3120 assert(obj->is_typeArray(),"must be a type array");
3121 }
3122
3123 ParMarkBitMapClosure::IterationStatus
3124 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3125 assert(destination() != NULL, "sanity");
3126 assert(bitmap()->obj_size(addr) == words, "bad size");
3127
3128 _source = addr;
3129 assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) ==
3130 destination(), "wrong destination");
3131
3132 if (words > words_remaining()) {
3133 return ParMarkBitMap::would_overflow;
3134 }
3135
3136 // The start_array must be updated even if the object is not moving.
3137 if (_start_array != NULL) {
3138 _start_array->allocate_block(destination());
3139 }
3140
3141 if (destination() != source()) {
3142 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3143 Copy::aligned_conjoint_words(source(), destination(), words);
3144 }
3145
3146 oop moved_oop = (oop) destination();
3147 compaction_manager()->update_contents(moved_oop);
3148 assert(moved_oop->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop));
3149
3150 update_state(words);
3151 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3152 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3153 }
3154
3155 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3156 ParCompactionManager* cm,
3157 PSParallelCompact::SpaceId space_id) :
3158 ParMarkBitMapClosure(mbm, cm),
3159 _space_id(space_id),
3160 _start_array(PSParallelCompact::start_array(space_id))
3161 {
3162 }
3163
3164 // Updates the references in the object to their new values.
3165 ParMarkBitMapClosure::IterationStatus
3166 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3167 do_addr(addr);
3168 return ParMarkBitMap::incomplete;
3169 }
3170
3171 ParMarkBitMapClosure::IterationStatus
3172 FillClosure::do_addr(HeapWord* addr, size_t size) {
3173 CollectedHeap::fill_with_objects(addr, size);
3174 HeapWord* const end = addr + size;
3175 do {
3176 _start_array->allocate_block(addr);
3177 addr += oop(addr)->size();
3178 } while (addr < end);
3179 return ParMarkBitMap::incomplete;
3180 }