1 /*
2 * Copyright (c) 2005, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "aot/aotLoader.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "code/codeCache.hpp"
31 #include "gc/parallel/gcTaskManager.hpp"
32 #include "gc/parallel/parallelScavengeHeap.inline.hpp"
33 #include "gc/parallel/parMarkBitMap.inline.hpp"
34 #include "gc/parallel/pcTasks.hpp"
35 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
36 #include "gc/parallel/psCompactionManager.inline.hpp"
37 #include "gc/parallel/psMarkSweep.hpp"
38 #include "gc/parallel/psMarkSweepDecorator.hpp"
39 #include "gc/parallel/psOldGen.hpp"
40 #include "gc/parallel/psParallelCompact.inline.hpp"
41 #include "gc/parallel/psPromotionManager.inline.hpp"
42 #include "gc/parallel/psScavenge.hpp"
43 #include "gc/parallel/psYoungGen.hpp"
44 #include "gc/shared/gcCause.hpp"
45 #include "gc/shared/gcHeapSummary.hpp"
46 #include "gc/shared/gcId.hpp"
47 #include "gc/shared/gcLocker.inline.hpp"
48 #include "gc/shared/gcTimer.hpp"
49 #include "gc/shared/gcTrace.hpp"
50 #include "gc/shared/gcTraceTime.inline.hpp"
51 #include "gc/shared/isGCActiveMark.hpp"
52 #include "gc/shared/referencePolicy.hpp"
53 #include "gc/shared/referenceProcessor.hpp"
54 #include "gc/shared/spaceDecorator.hpp"
55 #include "logging/log.hpp"
56 #include "memory/resourceArea.hpp"
57 #include "oops/instanceKlass.inline.hpp"
58 #include "oops/instanceMirrorKlass.inline.hpp"
59 #include "oops/methodData.hpp"
60 #include "oops/objArrayKlass.inline.hpp"
61 #include "oops/oop.inline.hpp"
62 #include "runtime/atomic.hpp"
63 #include "runtime/fprofiler.hpp"
64 #include "runtime/safepoint.hpp"
65 #include "runtime/vmThread.hpp"
66 #include "services/management.hpp"
67 #include "services/memTracker.hpp"
68 #include "services/memoryService.hpp"
69 #include "utilities/align.hpp"
70 #include "utilities/debug.hpp"
71 #include "utilities/events.hpp"
72 #include "utilities/formatBuffer.hpp"
73 #include "utilities/stack.inline.hpp"
74
75 #include <math.h>
76
77 // All sizes are in HeapWords.
78 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words
79 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
80 const size_t ParallelCompactData::RegionSizeBytes =
81 RegionSize << LogHeapWordSize;
82 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
83 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
84 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
85
86 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words
87 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize;
88 const size_t ParallelCompactData::BlockSizeBytes =
89 BlockSize << LogHeapWordSize;
90 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1;
91 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1;
92 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask;
93
94 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
95 const size_t ParallelCompactData::Log2BlocksPerRegion =
96 Log2RegionSize - Log2BlockSize;
97
98 const ParallelCompactData::RegionData::region_sz_t
99 ParallelCompactData::RegionData::dc_shift = 27;
100
101 const ParallelCompactData::RegionData::region_sz_t
102 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
103
104 const ParallelCompactData::RegionData::region_sz_t
105 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
106
107 const ParallelCompactData::RegionData::region_sz_t
108 ParallelCompactData::RegionData::los_mask = ~dc_mask;
109
110 const ParallelCompactData::RegionData::region_sz_t
111 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
112
113 const ParallelCompactData::RegionData::region_sz_t
114 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
115
116 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
117
118 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
119
120 double PSParallelCompact::_dwl_mean;
121 double PSParallelCompact::_dwl_std_dev;
122 double PSParallelCompact::_dwl_first_term;
123 double PSParallelCompact::_dwl_adjustment;
124 #ifdef ASSERT
125 bool PSParallelCompact::_dwl_initialized = false;
126 #endif // #ifdef ASSERT
127
128 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
129 HeapWord* destination)
130 {
131 assert(src_region_idx != 0, "invalid src_region_idx");
132 assert(partial_obj_size != 0, "invalid partial_obj_size argument");
133 assert(destination != NULL, "invalid destination argument");
134
135 _src_region_idx = src_region_idx;
136 _partial_obj_size = partial_obj_size;
137 _destination = destination;
138
139 // These fields may not be updated below, so make sure they're clear.
140 assert(_dest_region_addr == NULL, "should have been cleared");
141 assert(_first_src_addr == NULL, "should have been cleared");
142
143 // Determine the number of destination regions for the partial object.
144 HeapWord* const last_word = destination + partial_obj_size - 1;
145 const ParallelCompactData& sd = PSParallelCompact::summary_data();
146 HeapWord* const beg_region_addr = sd.region_align_down(destination);
147 HeapWord* const end_region_addr = sd.region_align_down(last_word);
148
149 if (beg_region_addr == end_region_addr) {
150 // One destination region.
151 _destination_count = 1;
152 if (end_region_addr == destination) {
153 // The destination falls on a region boundary, thus the first word of the
154 // partial object will be the first word copied to the destination region.
155 _dest_region_addr = end_region_addr;
156 _first_src_addr = sd.region_to_addr(src_region_idx);
157 }
158 } else {
159 // Two destination regions. When copied, the partial object will cross a
160 // destination region boundary, so a word somewhere within the partial
161 // object will be the first word copied to the second destination region.
162 _destination_count = 2;
163 _dest_region_addr = end_region_addr;
164 const size_t ofs = pointer_delta(end_region_addr, destination);
165 assert(ofs < _partial_obj_size, "sanity");
166 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
167 }
168 }
169
170 void SplitInfo::clear()
171 {
172 _src_region_idx = 0;
173 _partial_obj_size = 0;
174 _destination = NULL;
175 _destination_count = 0;
176 _dest_region_addr = NULL;
177 _first_src_addr = NULL;
178 assert(!is_valid(), "sanity");
179 }
180
181 #ifdef ASSERT
182 void SplitInfo::verify_clear()
183 {
184 assert(_src_region_idx == 0, "not clear");
185 assert(_partial_obj_size == 0, "not clear");
186 assert(_destination == NULL, "not clear");
187 assert(_destination_count == 0, "not clear");
188 assert(_dest_region_addr == NULL, "not clear");
189 assert(_first_src_addr == NULL, "not clear");
190 }
191 #endif // #ifdef ASSERT
192
193
194 void PSParallelCompact::print_on_error(outputStream* st) {
195 _mark_bitmap.print_on_error(st);
196 }
197
198 #ifndef PRODUCT
199 const char* PSParallelCompact::space_names[] = {
200 "old ", "eden", "from", "to "
201 };
202
203 void PSParallelCompact::print_region_ranges() {
204 if (!log_develop_is_enabled(Trace, gc, compaction)) {
205 return;
206 }
207 Log(gc, compaction) log;
208 ResourceMark rm;
209 LogStream ls(log.trace());
210 Universe::print_on(&ls);
211 log.trace("space bottom top end new_top");
212 log.trace("------ ---------- ---------- ---------- ----------");
213
214 for (unsigned int id = 0; id < last_space_id; ++id) {
215 const MutableSpace* space = _space_info[id].space();
216 log.trace("%u %s "
217 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
218 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
219 id, space_names[id],
220 summary_data().addr_to_region_idx(space->bottom()),
221 summary_data().addr_to_region_idx(space->top()),
222 summary_data().addr_to_region_idx(space->end()),
223 summary_data().addr_to_region_idx(_space_info[id].new_top()));
224 }
225 }
226
227 void
228 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
229 {
230 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7)
231 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5)
232
233 ParallelCompactData& sd = PSParallelCompact::summary_data();
234 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
235 log_develop_trace(gc, compaction)(
236 REGION_IDX_FORMAT " " PTR_FORMAT " "
237 REGION_IDX_FORMAT " " PTR_FORMAT " "
238 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
239 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
240 i, p2i(c->data_location()), dci, p2i(c->destination()),
241 c->partial_obj_size(), c->live_obj_size(),
242 c->data_size(), c->source_region(), c->destination_count());
243
244 #undef REGION_IDX_FORMAT
245 #undef REGION_DATA_FORMAT
246 }
247
248 void
249 print_generic_summary_data(ParallelCompactData& summary_data,
250 HeapWord* const beg_addr,
251 HeapWord* const end_addr)
252 {
253 size_t total_words = 0;
254 size_t i = summary_data.addr_to_region_idx(beg_addr);
255 const size_t last = summary_data.addr_to_region_idx(end_addr);
256 HeapWord* pdest = 0;
257
258 while (i < last) {
259 ParallelCompactData::RegionData* c = summary_data.region(i);
260 if (c->data_size() != 0 || c->destination() != pdest) {
261 print_generic_summary_region(i, c);
262 total_words += c->data_size();
263 pdest = c->destination();
264 }
265 ++i;
266 }
267
268 log_develop_trace(gc, compaction)("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
269 }
270
271 void
272 PSParallelCompact::print_generic_summary_data(ParallelCompactData& summary_data,
273 HeapWord* const beg_addr,
274 HeapWord* const end_addr) {
275 ::print_generic_summary_data(summary_data,beg_addr, end_addr);
276 }
277
278 void
279 print_generic_summary_data(ParallelCompactData& summary_data,
280 SpaceInfo* space_info)
281 {
282 if (!log_develop_is_enabled(Trace, gc, compaction)) {
283 return;
284 }
285
286 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
287 const MutableSpace* space = space_info[id].space();
288 print_generic_summary_data(summary_data, space->bottom(),
289 MAX2(space->top(), space_info[id].new_top()));
290 }
291 }
292
293 void
294 print_initial_summary_data(ParallelCompactData& summary_data,
295 const MutableSpace* space) {
296 if (space->top() == space->bottom()) {
297 return;
298 }
299
300 const size_t region_size = ParallelCompactData::RegionSize;
301 typedef ParallelCompactData::RegionData RegionData;
302 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
303 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
304 const RegionData* c = summary_data.region(end_region - 1);
305 HeapWord* end_addr = c->destination() + c->data_size();
306 const size_t live_in_space = pointer_delta(end_addr, space->bottom());
307
308 // Print (and count) the full regions at the beginning of the space.
309 size_t full_region_count = 0;
310 size_t i = summary_data.addr_to_region_idx(space->bottom());
311 while (i < end_region && summary_data.region(i)->data_size() == region_size) {
312 ParallelCompactData::RegionData* c = summary_data.region(i);
313 log_develop_trace(gc, compaction)(
314 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
315 i, p2i(c->destination()),
316 c->partial_obj_size(), c->live_obj_size(),
317 c->data_size(), c->source_region(), c->destination_count());
318 ++full_region_count;
319 ++i;
320 }
321
322 size_t live_to_right = live_in_space - full_region_count * region_size;
323
324 double max_reclaimed_ratio = 0.0;
325 size_t max_reclaimed_ratio_region = 0;
326 size_t max_dead_to_right = 0;
327 size_t max_live_to_right = 0;
328
329 // Print the 'reclaimed ratio' for regions while there is something live in
330 // the region or to the right of it. The remaining regions are empty (and
331 // uninteresting), and computing the ratio will result in division by 0.
332 while (i < end_region && live_to_right > 0) {
333 c = summary_data.region(i);
334 HeapWord* const region_addr = summary_data.region_to_addr(i);
335 const size_t used_to_right = pointer_delta(space->top(), region_addr);
336 const size_t dead_to_right = used_to_right - live_to_right;
337 const double reclaimed_ratio = double(dead_to_right) / live_to_right;
338
339 if (reclaimed_ratio > max_reclaimed_ratio) {
340 max_reclaimed_ratio = reclaimed_ratio;
341 max_reclaimed_ratio_region = i;
342 max_dead_to_right = dead_to_right;
343 max_live_to_right = live_to_right;
344 }
345
346 ParallelCompactData::RegionData* c = summary_data.region(i);
347 log_develop_trace(gc, compaction)(
348 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d"
349 "%12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
350 i, p2i(c->destination()),
351 c->partial_obj_size(), c->live_obj_size(),
352 c->data_size(), c->source_region(), c->destination_count(),
353 reclaimed_ratio, dead_to_right, live_to_right);
354
355
356 live_to_right -= c->data_size();
357 ++i;
358 }
359
360 // Any remaining regions are empty. Print one more if there is one.
361 if (i < end_region) {
362 ParallelCompactData::RegionData* c = summary_data.region(i);
363 log_develop_trace(gc, compaction)(
364 SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
365 i, p2i(c->destination()),
366 c->partial_obj_size(), c->live_obj_size(),
367 c->data_size(), c->source_region(), c->destination_count());
368 }
369
370 log_develop_trace(gc, compaction)("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
371 max_reclaimed_ratio_region, max_dead_to_right, max_live_to_right, max_reclaimed_ratio);
372 }
373
374 void
375 print_initial_summary_data(ParallelCompactData& summary_data,
376 SpaceInfo* space_info) {
377 if (!log_develop_is_enabled(Trace, gc, compaction)) {
378 return;
379 }
380
381 unsigned int id = PSParallelCompact::old_space_id;
382 const MutableSpace* space;
383 do {
384 space = space_info[id].space();
385 print_initial_summary_data(summary_data, space);
386 } while (++id < PSParallelCompact::eden_space_id);
387
388 do {
389 space = space_info[id].space();
390 print_generic_summary_data(summary_data, space->bottom(), space->top());
391 } while (++id < PSParallelCompact::last_space_id);
392 }
393 #endif // #ifndef PRODUCT
394
395 #ifdef ASSERT
396 size_t add_obj_count;
397 size_t add_obj_size;
398 size_t mark_bitmap_count;
399 size_t mark_bitmap_size;
400 #endif // #ifdef ASSERT
401
402 ParallelCompactData::ParallelCompactData()
403 {
404 _region_start = 0;
405
406 _region_vspace = 0;
407 _reserved_byte_size = 0;
408 _region_data = 0;
409 _region_count = 0;
410
411 _block_vspace = 0;
412 _block_data = 0;
413 _block_count = 0;
414 }
415
416 bool ParallelCompactData::initialize(MemRegion covered_region)
417 {
418 _region_start = covered_region.start();
419 const size_t region_size = covered_region.word_size();
420 DEBUG_ONLY(_region_end = _region_start + region_size;)
421
422 assert(region_align_down(_region_start) == _region_start,
423 "region start not aligned");
424 assert((region_size & RegionSizeOffsetMask) == 0,
425 "region size not a multiple of RegionSize");
426
427 bool result = initialize_region_data(region_size) && initialize_block_data();
428 return result;
429 }
430
431 PSVirtualSpace*
432 ParallelCompactData::create_vspace(size_t count, size_t element_size)
433 {
434 const size_t raw_bytes = count * element_size;
435 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
436 const size_t granularity = os::vm_allocation_granularity();
437 _reserved_byte_size = align_up(raw_bytes, MAX2(page_sz, granularity));
438
439 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
440 MAX2(page_sz, granularity);
441 ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0);
442 os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, page_sz, rs.base(),
443 rs.size());
444
445 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
446
447 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
448 if (vspace != 0) {
449 if (vspace->expand_by(_reserved_byte_size)) {
450 return vspace;
451 }
452 delete vspace;
453 // Release memory reserved in the space.
454 rs.release();
455 }
456
457 return 0;
458 }
459
460 bool ParallelCompactData::initialize_region_data(size_t region_size)
461 {
462 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
463 _region_vspace = create_vspace(count, sizeof(RegionData));
464 if (_region_vspace != 0) {
465 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
466 _region_count = count;
467 return true;
468 }
469 return false;
470 }
471
472 bool ParallelCompactData::initialize_block_data()
473 {
474 assert(_region_count != 0, "region data must be initialized first");
475 const size_t count = _region_count << Log2BlocksPerRegion;
476 _block_vspace = create_vspace(count, sizeof(BlockData));
477 if (_block_vspace != 0) {
478 _block_data = (BlockData*)_block_vspace->reserved_low_addr();
479 _block_count = count;
480 return true;
481 }
482 return false;
483 }
484
485 void ParallelCompactData::clear()
486 {
487 memset(_region_data, 0, _region_vspace->committed_size());
488 memset(_block_data, 0, _block_vspace->committed_size());
489 }
490
491 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
492 assert(beg_region <= _region_count, "beg_region out of range");
493 assert(end_region <= _region_count, "end_region out of range");
494 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize");
495
496 const size_t region_cnt = end_region - beg_region;
497 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
498
499 const size_t beg_block = beg_region * BlocksPerRegion;
500 const size_t block_cnt = region_cnt * BlocksPerRegion;
501 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));
502 }
503
504 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
505 {
506 const RegionData* cur_cp = region(region_idx);
507 const RegionData* const end_cp = region(region_count() - 1);
508
509 HeapWord* result = region_to_addr(region_idx);
510 if (cur_cp < end_cp) {
511 do {
512 result += cur_cp->partial_obj_size();
513 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
514 }
515 return result;
516 }
517
518 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
519 {
520 const size_t obj_ofs = pointer_delta(addr, _region_start);
521 const size_t beg_region = obj_ofs >> Log2RegionSize;
522 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
523
524 DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
525 DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
526
527 if (beg_region == end_region) {
528 // All in one region.
529 _region_data[beg_region].add_live_obj(len);
530 return;
531 }
532
533 // First region.
534 const size_t beg_ofs = region_offset(addr);
535 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
536
537 Klass* klass = ((oop)addr)->klass();
538 // Middle regions--completely spanned by this object.
539 for (size_t region = beg_region + 1; region < end_region; ++region) {
540 _region_data[region].set_partial_obj_size(RegionSize);
541 _region_data[region].set_partial_obj_addr(addr);
542 }
543
544 // Last region.
545 const size_t end_ofs = region_offset(addr + len - 1);
546 _region_data[end_region].set_partial_obj_size(end_ofs + 1);
547 _region_data[end_region].set_partial_obj_addr(addr);
548 }
549
550 void
551 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
552 {
553 assert(region_offset(beg) == 0, "not RegionSize aligned");
554 assert(region_offset(end) == 0, "not RegionSize aligned");
555
556 size_t cur_region = addr_to_region_idx(beg);
557 const size_t end_region = addr_to_region_idx(end);
558 HeapWord* addr = beg;
559 while (cur_region < end_region) {
560 _region_data[cur_region].set_destination(addr);
561 _region_data[cur_region].set_destination_count(0);
562 _region_data[cur_region].set_source_region(cur_region);
563 _region_data[cur_region].set_data_location(addr);
564
565 // Update live_obj_size so the region appears completely full.
566 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
567 _region_data[cur_region].set_live_obj_size(live_size);
568
569 ++cur_region;
570 addr += RegionSize;
571 }
572 }
573
574 // Find the point at which a space can be split and, if necessary, record the
575 // split point.
576 //
577 // If the current src region (which overflowed the destination space) doesn't
578 // have a partial object, the split point is at the beginning of the current src
579 // region (an "easy" split, no extra bookkeeping required).
580 //
581 // If the current src region has a partial object, the split point is in the
582 // region where that partial object starts (call it the split_region). If
583 // split_region has a partial object, then the split point is just after that
584 // partial object (a "hard" split where we have to record the split data and
585 // zero the partial_obj_size field). With a "hard" split, we know that the
586 // partial_obj ends within split_region because the partial object that caused
587 // the overflow starts in split_region. If split_region doesn't have a partial
588 // obj, then the split is at the beginning of split_region (another "easy"
589 // split).
590 HeapWord*
591 ParallelCompactData::summarize_split_space(size_t src_region,
592 SplitInfo& split_info,
593 HeapWord* destination,
594 HeapWord* target_end,
595 HeapWord** target_next)
596 {
597 assert(destination <= target_end, "sanity");
598 assert(destination + _region_data[src_region].data_size() > target_end,
599 "region should not fit into target space");
600 assert(is_region_aligned(target_end), "sanity");
601
602 size_t split_region = src_region;
603 HeapWord* split_destination = destination;
604 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
605
606 if (destination + partial_obj_size > target_end) {
607 // The split point is just after the partial object (if any) in the
608 // src_region that contains the start of the object that overflowed the
609 // destination space.
610 //
611 // Find the start of the "overflow" object and set split_region to the
612 // region containing it.
613 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
614 split_region = addr_to_region_idx(overflow_obj);
615
616 // Clear the source_region field of all destination regions whose first word
617 // came from data after the split point (a non-null source_region field
618 // implies a region must be filled).
619 //
620 // An alternative to the simple loop below: clear during post_compact(),
621 // which uses memcpy instead of individual stores, and is easy to
622 // parallelize. (The downside is that it clears the entire RegionData
623 // object as opposed to just one field.)
624 //
625 // post_compact() would have to clear the summary data up to the highest
626 // address that was written during the summary phase, which would be
627 //
628 // max(top, max(new_top, clear_top))
629 //
630 // where clear_top is a new field in SpaceInfo. Would have to set clear_top
631 // to target_end.
632 const RegionData* const sr = region(split_region);
633 const size_t beg_idx =
634 addr_to_region_idx(region_align_up(sr->destination() +
635 sr->partial_obj_size()));
636 const size_t end_idx = addr_to_region_idx(target_end);
637
638 log_develop_trace(gc, compaction)("split: clearing source_region field in [" SIZE_FORMAT ", " SIZE_FORMAT ")", beg_idx, end_idx);
639 for (size_t idx = beg_idx; idx < end_idx; ++idx) {
640 _region_data[idx].set_source_region(0);
641 }
642
643 // Set split_destination and partial_obj_size to reflect the split region.
644 split_destination = sr->destination();
645 partial_obj_size = sr->partial_obj_size();
646 }
647
648 // The split is recorded only if a partial object extends onto the region.
649 if (partial_obj_size != 0) {
650 _region_data[split_region].set_partial_obj_size(0);
651 split_info.record(split_region, partial_obj_size, split_destination);
652 }
653
654 // Setup the continuation addresses.
655 *target_next = split_destination + partial_obj_size;
656 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
657
658 if (log_develop_is_enabled(Trace, gc, compaction)) {
659 const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
660 log_develop_trace(gc, compaction)("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT " pos=" SIZE_FORMAT,
661 split_type, p2i(source_next), split_region, partial_obj_size);
662 log_develop_trace(gc, compaction)("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT " tn=" PTR_FORMAT,
663 split_type, p2i(split_destination),
664 addr_to_region_idx(split_destination),
665 p2i(*target_next));
666
667 if (partial_obj_size != 0) {
668 HeapWord* const po_beg = split_info.destination();
669 HeapWord* const po_end = po_beg + split_info.partial_obj_size();
670 log_develop_trace(gc, compaction)("%s split: po_beg=" PTR_FORMAT " " SIZE_FORMAT " po_end=" PTR_FORMAT " " SIZE_FORMAT,
671 split_type,
672 p2i(po_beg), addr_to_region_idx(po_beg),
673 p2i(po_end), addr_to_region_idx(po_end));
674 }
675 }
676
677 return source_next;
678 }
679
680 bool ParallelCompactData::summarize(SplitInfo& split_info,
681 HeapWord* source_beg, HeapWord* source_end,
682 HeapWord** source_next,
683 HeapWord* target_beg, HeapWord* target_end,
684 HeapWord** target_next)
685 {
686 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
687 log_develop_trace(gc, compaction)(
688 "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
689 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
690 p2i(source_beg), p2i(source_end), p2i(source_next_val),
691 p2i(target_beg), p2i(target_end), p2i(*target_next));
692
693 size_t cur_region = addr_to_region_idx(source_beg);
694 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
695
696 HeapWord *dest_addr = target_beg;
697 while (cur_region < end_region) {
698 // The destination must be set even if the region has no data.
699 _region_data[cur_region].set_destination(dest_addr);
700
701 size_t words = _region_data[cur_region].data_size();
702 if (words > 0) {
703 // If cur_region does not fit entirely into the target space, find a point
704 // at which the source space can be 'split' so that part is copied to the
705 // target space and the rest is copied elsewhere.
706 if (dest_addr + words > target_end) {
707 assert(source_next != NULL, "source_next is NULL when splitting");
708 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
709 target_end, target_next);
710 return false;
711 }
712
713 // Compute the destination_count for cur_region, and if necessary, update
714 // source_region for a destination region. The source_region field is
715 // updated if cur_region is the first (left-most) region to be copied to a
716 // destination region.
717 //
718 // The destination_count calculation is a bit subtle. A region that has
719 // data that compacts into itself does not count itself as a destination.
720 // This maintains the invariant that a zero count means the region is
721 // available and can be claimed and then filled.
722 uint destination_count = 0;
723 if (split_info.is_split(cur_region)) {
724 // The current region has been split: the partial object will be copied
725 // to one destination space and the remaining data will be copied to
726 // another destination space. Adjust the initial destination_count and,
727 // if necessary, set the source_region field if the partial object will
728 // cross a destination region boundary.
729 destination_count = split_info.destination_count();
730 if (destination_count == 2) {
731 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
732 _region_data[dest_idx].set_source_region(cur_region);
733 }
734 }
735
736 HeapWord* const last_addr = dest_addr + words - 1;
737 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
738 const size_t dest_region_2 = addr_to_region_idx(last_addr);
739
740 // Initially assume that the destination regions will be the same and
741 // adjust the value below if necessary. Under this assumption, if
742 // cur_region == dest_region_2, then cur_region will be compacted
743 // completely into itself.
744 destination_count += cur_region == dest_region_2 ? 0 : 1;
745 if (dest_region_1 != dest_region_2) {
746 // Destination regions differ; adjust destination_count.
747 destination_count += 1;
748 // Data from cur_region will be copied to the start of dest_region_2.
749 _region_data[dest_region_2].set_source_region(cur_region);
750 } else if (region_offset(dest_addr) == 0) {
751 // Data from cur_region will be copied to the start of the destination
752 // region.
753 _region_data[dest_region_1].set_source_region(cur_region);
754 }
755
756 _region_data[cur_region].set_destination_count(destination_count);
757 _region_data[cur_region].set_data_location(region_to_addr(cur_region));
758 dest_addr += words;
759 }
760
761 ++cur_region;
762 }
763
764 *target_next = dest_addr;
765 return true;
766 }
767
768 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr, ParCompactionManager* cm) {
769 assert(addr != NULL, "Should detect NULL oop earlier");
770 assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap");
771 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked");
772
773 // Region covering the object.
774 RegionData* const region_ptr = addr_to_region_ptr(addr);
775 HeapWord* result = region_ptr->destination();
776
777 // If the entire Region is live, the new location is region->destination + the
778 // offset of the object within in the Region.
779
780 // Run some performance tests to determine if this special case pays off. It
781 // is worth it for pointers into the dense prefix. If the optimization to
782 // avoid pointer updates in regions that only point to the dense prefix is
783 // ever implemented, this should be revisited.
784 if (region_ptr->data_size() == RegionSize) {
785 result += region_offset(addr);
786 return result;
787 }
788
789 // Otherwise, the new location is region->destination + block offset + the
790 // number of live words in the Block that are (a) to the left of addr and (b)
791 // due to objects that start in the Block.
792
793 // Fill in the block table if necessary. This is unsynchronized, so multiple
794 // threads may fill the block table for a region (harmless, since it is
795 // idempotent).
796 if (!region_ptr->blocks_filled()) {
797 PSParallelCompact::fill_blocks(addr_to_region_idx(addr));
798 region_ptr->set_blocks_filled();
799 }
800
801 HeapWord* const search_start = block_align_down(addr);
802 const size_t block_offset = addr_to_block_ptr(addr)->offset();
803
804 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
805 const size_t live = bitmap->live_words_in_range(cm, search_start, oop(addr));
806 result += block_offset + live;
807 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result));
808 return result;
809 }
810
811 #ifdef ASSERT
812 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
813 {
814 const size_t* const beg = (const size_t*)vspace->committed_low_addr();
815 const size_t* const end = (const size_t*)vspace->committed_high_addr();
816 for (const size_t* p = beg; p < end; ++p) {
817 assert(*p == 0, "not zero");
818 }
819 }
820
821 void ParallelCompactData::verify_clear()
822 {
823 verify_clear(_region_vspace);
824 verify_clear(_block_vspace);
825 }
826 #endif // #ifdef ASSERT
827
828 STWGCTimer PSParallelCompact::_gc_timer;
829 ParallelOldTracer PSParallelCompact::_gc_tracer;
830 elapsedTimer PSParallelCompact::_accumulated_time;
831 unsigned int PSParallelCompact::_total_invocations = 0;
832 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
833 jlong PSParallelCompact::_time_of_last_gc = 0;
834 CollectorCounters* PSParallelCompact::_counters = NULL;
835 ParMarkBitMap PSParallelCompact::_mark_bitmap;
836 ParallelCompactData PSParallelCompact::_summary_data;
837
838 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
839
840 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
841
842 void PSParallelCompact::AdjustKlassClosure::do_klass(Klass* klass) {
843 PSParallelCompact::AdjustPointerClosure closure(_cm);
844 klass->oops_do(&closure);
845 }
846
847 void PSParallelCompact::post_initialize() {
848 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
849 MemRegion mr = heap->reserved_region();
850 _ref_processor =
851 new ReferenceProcessor(mr, // span
852 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
853 ParallelGCThreads, // mt processing degree
854 true, // mt discovery
855 ParallelGCThreads, // mt discovery degree
856 true, // atomic_discovery
857 &_is_alive_closure); // non-header is alive closure
858 _counters = new CollectorCounters("PSParallelCompact", 1);
859
860 // Initialize static fields in ParCompactionManager.
861 ParCompactionManager::initialize(mark_bitmap());
862 }
863
864 bool PSParallelCompact::initialize() {
865 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
866 MemRegion mr = heap->reserved_region();
867
868 // Was the old gen get allocated successfully?
869 if (!heap->old_gen()->is_allocated()) {
870 return false;
871 }
872
873 initialize_space_info();
874 initialize_dead_wood_limiter();
875
876 if (!_mark_bitmap.initialize(mr)) {
877 vm_shutdown_during_initialization(
878 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
879 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
880 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
881 return false;
882 }
883
884 if (!_summary_data.initialize(mr)) {
885 vm_shutdown_during_initialization(
886 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
887 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
888 _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
889 return false;
890 }
891
892 return true;
893 }
894
895 void PSParallelCompact::initialize_space_info()
896 {
897 memset(&_space_info, 0, sizeof(_space_info));
898
899 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
900 PSYoungGen* young_gen = heap->young_gen();
901
902 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
903 _space_info[eden_space_id].set_space(young_gen->eden_space());
904 _space_info[from_space_id].set_space(young_gen->from_space());
905 _space_info[to_space_id].set_space(young_gen->to_space());
906
907 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
908 }
909
910 void PSParallelCompact::initialize_dead_wood_limiter()
911 {
912 const size_t max = 100;
913 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
914 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
915 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
916 DEBUG_ONLY(_dwl_initialized = true;)
917 _dwl_adjustment = normal_distribution(1.0);
918 }
919
920 void
921 PSParallelCompact::clear_data_covering_space(SpaceId id)
922 {
923 // At this point, top is the value before GC, new_top() is the value that will
924 // be set at the end of GC. The marking bitmap is cleared to top; nothing
925 // should be marked above top. The summary data is cleared to the larger of
926 // top & new_top.
927 MutableSpace* const space = _space_info[id].space();
928 HeapWord* const bot = space->bottom();
929 HeapWord* const top = space->top();
930 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
931
932 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
933 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
934 _mark_bitmap.clear_range(beg_bit, end_bit);
935
936 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
937 const size_t end_region =
938 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
939 _summary_data.clear_range(beg_region, end_region);
940
941 // Clear the data used to 'split' regions.
942 SplitInfo& split_info = _space_info[id].split_info();
943 if (split_info.is_valid()) {
944 split_info.clear();
945 }
946 DEBUG_ONLY(split_info.verify_clear();)
947 }
948
949 void PSParallelCompact::pre_compact()
950 {
951 // Update the from & to space pointers in space_info, since they are swapped
952 // at each young gen gc. Do the update unconditionally (even though a
953 // promotion failure does not swap spaces) because an unknown number of young
954 // collections will have swapped the spaces an unknown number of times.
955 GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer);
956 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
957 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
958 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
959
960 DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
961 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
962
963 // Increment the invocation count
964 heap->increment_total_collections(true);
965
966 // We need to track unique mark sweep invocations as well.
967 _total_invocations++;
968
969 heap->print_heap_before_gc();
970 heap->trace_heap_before_gc(&_gc_tracer);
971
972 // Fill in TLABs
973 heap->accumulate_statistics_all_tlabs();
974 heap->ensure_parsability(true); // retire TLABs
975
976 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
977 HandleMark hm; // Discard invalid handles created during verification
978 Universe::verify("Before GC");
979 }
980
981 // Verify object start arrays
982 if (VerifyObjectStartArray &&
983 VerifyBeforeGC) {
984 heap->old_gen()->verify_object_start_array();
985 }
986
987 DEBUG_ONLY(mark_bitmap()->verify_clear();)
988 DEBUG_ONLY(summary_data().verify_clear();)
989
990 // Have worker threads release resources the next time they run a task.
991 gc_task_manager()->release_all_resources();
992
993 ParCompactionManager::reset_all_bitmap_query_caches();
994 }
995
996 void PSParallelCompact::post_compact()
997 {
998 GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer);
999
1000 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1001 // Clear the marking bitmap, summary data and split info.
1002 clear_data_covering_space(SpaceId(id));
1003 // Update top(). Must be done after clearing the bitmap and summary data.
1004 _space_info[id].publish_new_top();
1005 }
1006
1007 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1008 MutableSpace* const from_space = _space_info[from_space_id].space();
1009 MutableSpace* const to_space = _space_info[to_space_id].space();
1010
1011 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1012 bool eden_empty = eden_space->is_empty();
1013 if (!eden_empty) {
1014 eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1015 heap->young_gen(), heap->old_gen());
1016 }
1017
1018 // Update heap occupancy information which is used as input to the soft ref
1019 // clearing policy at the next gc.
1020 Universe::update_heap_info_at_gc();
1021
1022 bool young_gen_empty = eden_empty && from_space->is_empty() &&
1023 to_space->is_empty();
1024
1025 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set());
1026 MemRegion old_mr = heap->old_gen()->reserved();
1027 if (young_gen_empty) {
1028 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
1029 } else {
1030 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1031 }
1032
1033 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1034 ClassLoaderDataGraph::purge();
1035 MetaspaceAux::verify_metrics();
1036
1037 CodeCache::gc_epilogue();
1038 JvmtiExport::gc_epilogue();
1039
1040 #if defined(COMPILER2) || INCLUDE_JVMCI
1041 DerivedPointerTable::update_pointers();
1042 #endif
1043
1044 ReferenceProcessorPhaseTimes pt(&_gc_timer,
1045 ref_processor()->num_q(),
1046 ref_processor()->processing_is_mt());
1047
1048 ref_processor()->enqueue_discovered_references(NULL, &pt);
1049
1050 pt.print_enqueue_phase();
1051
1052 if (ZapUnusedHeapArea) {
1053 heap->gen_mangle_unused_area();
1054 }
1055
1056 // Update time of last GC
1057 reset_millis_since_last_gc();
1058 }
1059
1060 HeapWord*
1061 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1062 bool maximum_compaction)
1063 {
1064 const size_t region_size = ParallelCompactData::RegionSize;
1065 const ParallelCompactData& sd = summary_data();
1066
1067 const MutableSpace* const space = _space_info[id].space();
1068 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1069 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1070 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1071
1072 // Skip full regions at the beginning of the space--they are necessarily part
1073 // of the dense prefix.
1074 size_t full_count = 0;
1075 const RegionData* cp;
1076 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1077 ++full_count;
1078 }
1079
1080 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1081 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1082 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1083 if (maximum_compaction || cp == end_cp || interval_ended) {
1084 _maximum_compaction_gc_num = total_invocations();
1085 return sd.region_to_addr(cp);
1086 }
1087
1088 HeapWord* const new_top = _space_info[id].new_top();
1089 const size_t space_live = pointer_delta(new_top, space->bottom());
1090 const size_t space_used = space->used_in_words();
1091 const size_t space_capacity = space->capacity_in_words();
1092
1093 const double cur_density = double(space_live) / space_capacity;
1094 const double deadwood_density =
1095 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1096 const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1097
1098 if (TraceParallelOldGCDensePrefix) {
1099 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1100 cur_density, deadwood_density, deadwood_goal);
1101 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1102 "space_cap=" SIZE_FORMAT,
1103 space_live, space_used,
1104 space_capacity);
1105 }
1106
1107 // XXX - Use binary search?
1108 HeapWord* dense_prefix = sd.region_to_addr(cp);
1109 const RegionData* full_cp = cp;
1110 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1111 while (cp < end_cp) {
1112 HeapWord* region_destination = cp->destination();
1113 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1114 if (TraceParallelOldGCDensePrefix && Verbose) {
1115 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1116 "dp=" PTR_FORMAT " " "cdw=" SIZE_FORMAT_W(8),
1117 sd.region(cp), p2i(region_destination),
1118 p2i(dense_prefix), cur_deadwood);
1119 }
1120
1121 if (cur_deadwood >= deadwood_goal) {
1122 // Found the region that has the correct amount of deadwood to the left.
1123 // This typically occurs after crossing a fairly sparse set of regions, so
1124 // iterate backwards over those sparse regions, looking for the region
1125 // that has the lowest density of live objects 'to the right.'
1126 size_t space_to_left = sd.region(cp) * region_size;
1127 size_t live_to_left = space_to_left - cur_deadwood;
1128 size_t space_to_right = space_capacity - space_to_left;
1129 size_t live_to_right = space_live - live_to_left;
1130 double density_to_right = double(live_to_right) / space_to_right;
1131 while (cp > full_cp) {
1132 --cp;
1133 const size_t prev_region_live_to_right = live_to_right -
1134 cp->data_size();
1135 const size_t prev_region_space_to_right = space_to_right + region_size;
1136 double prev_region_density_to_right =
1137 double(prev_region_live_to_right) / prev_region_space_to_right;
1138 if (density_to_right <= prev_region_density_to_right) {
1139 return dense_prefix;
1140 }
1141 if (TraceParallelOldGCDensePrefix && Verbose) {
1142 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1143 "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1144 prev_region_density_to_right);
1145 }
1146 dense_prefix -= region_size;
1147 live_to_right = prev_region_live_to_right;
1148 space_to_right = prev_region_space_to_right;
1149 density_to_right = prev_region_density_to_right;
1150 }
1151 return dense_prefix;
1152 }
1153
1154 dense_prefix += region_size;
1155 ++cp;
1156 }
1157
1158 return dense_prefix;
1159 }
1160
1161 #ifndef PRODUCT
1162 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1163 const SpaceId id,
1164 const bool maximum_compaction,
1165 HeapWord* const addr)
1166 {
1167 const size_t region_idx = summary_data().addr_to_region_idx(addr);
1168 RegionData* const cp = summary_data().region(region_idx);
1169 const MutableSpace* const space = _space_info[id].space();
1170 HeapWord* const new_top = _space_info[id].new_top();
1171
1172 const size_t space_live = pointer_delta(new_top, space->bottom());
1173 const size_t dead_to_left = pointer_delta(addr, cp->destination());
1174 const size_t space_cap = space->capacity_in_words();
1175 const double dead_to_left_pct = double(dead_to_left) / space_cap;
1176 const size_t live_to_right = new_top - cp->destination();
1177 const size_t dead_to_right = space->top() - addr - live_to_right;
1178
1179 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1180 "spl=" SIZE_FORMAT " "
1181 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1182 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1183 " ratio=%10.8f",
1184 algorithm, p2i(addr), region_idx,
1185 space_live,
1186 dead_to_left, dead_to_left_pct,
1187 dead_to_right, live_to_right,
1188 double(dead_to_right) / live_to_right);
1189 }
1190 #endif // #ifndef PRODUCT
1191
1192 // Return a fraction indicating how much of the generation can be treated as
1193 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution
1194 // based on the density of live objects in the generation to determine a limit,
1195 // which is then adjusted so the return value is min_percent when the density is
1196 // 1.
1197 //
1198 // The following table shows some return values for a different values of the
1199 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1200 // min_percent is 1.
1201 //
1202 // fraction allowed as dead wood
1203 // -----------------------------------------------------------------
1204 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1205 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1206 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1207 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1208 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1209 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1210 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1211 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1212 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1213 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1214 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1215 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1216 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1217 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1218 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1219 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1220 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1221 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1222 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1223 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1224 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1225 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1226 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1227
1228 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1229 {
1230 assert(_dwl_initialized, "uninitialized");
1231
1232 // The raw limit is the value of the normal distribution at x = density.
1233 const double raw_limit = normal_distribution(density);
1234
1235 // Adjust the raw limit so it becomes the minimum when the density is 1.
1236 //
1237 // First subtract the adjustment value (which is simply the precomputed value
1238 // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1239 // Then add the minimum value, so the minimum is returned when the density is
1240 // 1. Finally, prevent negative values, which occur when the mean is not 0.5.
1241 const double min = double(min_percent) / 100.0;
1242 const double limit = raw_limit - _dwl_adjustment + min;
1243 return MAX2(limit, 0.0);
1244 }
1245
1246 ParallelCompactData::RegionData*
1247 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1248 const RegionData* end)
1249 {
1250 const size_t region_size = ParallelCompactData::RegionSize;
1251 ParallelCompactData& sd = summary_data();
1252 size_t left = sd.region(beg);
1253 size_t right = end > beg ? sd.region(end) - 1 : left;
1254
1255 // Binary search.
1256 while (left < right) {
1257 // Equivalent to (left + right) / 2, but does not overflow.
1258 const size_t middle = left + (right - left) / 2;
1259 RegionData* const middle_ptr = sd.region(middle);
1260 HeapWord* const dest = middle_ptr->destination();
1261 HeapWord* const addr = sd.region_to_addr(middle);
1262 assert(dest != NULL, "sanity");
1263 assert(dest <= addr, "must move left");
1264
1265 if (middle > left && dest < addr) {
1266 right = middle - 1;
1267 } else if (middle < right && middle_ptr->data_size() == region_size) {
1268 left = middle + 1;
1269 } else {
1270 return middle_ptr;
1271 }
1272 }
1273 return sd.region(left);
1274 }
1275
1276 ParallelCompactData::RegionData*
1277 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1278 const RegionData* end,
1279 size_t dead_words)
1280 {
1281 ParallelCompactData& sd = summary_data();
1282 size_t left = sd.region(beg);
1283 size_t right = end > beg ? sd.region(end) - 1 : left;
1284
1285 // Binary search.
1286 while (left < right) {
1287 // Equivalent to (left + right) / 2, but does not overflow.
1288 const size_t middle = left + (right - left) / 2;
1289 RegionData* const middle_ptr = sd.region(middle);
1290 HeapWord* const dest = middle_ptr->destination();
1291 HeapWord* const addr = sd.region_to_addr(middle);
1292 assert(dest != NULL, "sanity");
1293 assert(dest <= addr, "must move left");
1294
1295 const size_t dead_to_left = pointer_delta(addr, dest);
1296 if (middle > left && dead_to_left > dead_words) {
1297 right = middle - 1;
1298 } else if (middle < right && dead_to_left < dead_words) {
1299 left = middle + 1;
1300 } else {
1301 return middle_ptr;
1302 }
1303 }
1304 return sd.region(left);
1305 }
1306
1307 // The result is valid during the summary phase, after the initial summarization
1308 // of each space into itself, and before final summarization.
1309 inline double
1310 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1311 HeapWord* const bottom,
1312 HeapWord* const top,
1313 HeapWord* const new_top)
1314 {
1315 ParallelCompactData& sd = summary_data();
1316
1317 assert(cp != NULL, "sanity");
1318 assert(bottom != NULL, "sanity");
1319 assert(top != NULL, "sanity");
1320 assert(new_top != NULL, "sanity");
1321 assert(top >= new_top, "summary data problem?");
1322 assert(new_top > bottom, "space is empty; should not be here");
1323 assert(new_top >= cp->destination(), "sanity");
1324 assert(top >= sd.region_to_addr(cp), "sanity");
1325
1326 HeapWord* const destination = cp->destination();
1327 const size_t dense_prefix_live = pointer_delta(destination, bottom);
1328 const size_t compacted_region_live = pointer_delta(new_top, destination);
1329 const size_t compacted_region_used = pointer_delta(top,
1330 sd.region_to_addr(cp));
1331 const size_t reclaimable = compacted_region_used - compacted_region_live;
1332
1333 const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1334 return double(reclaimable) / divisor;
1335 }
1336
1337 // Return the address of the end of the dense prefix, a.k.a. the start of the
1338 // compacted region. The address is always on a region boundary.
1339 //
1340 // Completely full regions at the left are skipped, since no compaction can
1341 // occur in those regions. Then the maximum amount of dead wood to allow is
1342 // computed, based on the density (amount live / capacity) of the generation;
1343 // the region with approximately that amount of dead space to the left is
1344 // identified as the limit region. Regions between the last completely full
1345 // region and the limit region are scanned and the one that has the best
1346 // (maximum) reclaimed_ratio() is selected.
1347 HeapWord*
1348 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1349 bool maximum_compaction)
1350 {
1351 const size_t region_size = ParallelCompactData::RegionSize;
1352 const ParallelCompactData& sd = summary_data();
1353
1354 const MutableSpace* const space = _space_info[id].space();
1355 HeapWord* const top = space->top();
1356 HeapWord* const top_aligned_up = sd.region_align_up(top);
1357 HeapWord* const new_top = _space_info[id].new_top();
1358 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1359 HeapWord* const bottom = space->bottom();
1360 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1361 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1362 const RegionData* const new_top_cp =
1363 sd.addr_to_region_ptr(new_top_aligned_up);
1364
1365 // Skip full regions at the beginning of the space--they are necessarily part
1366 // of the dense prefix.
1367 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1368 assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1369 space->is_empty(), "no dead space allowed to the left");
1370 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1371 "region must have dead space");
1372
1373 // The gc number is saved whenever a maximum compaction is done, and used to
1374 // determine when the maximum compaction interval has expired. This avoids
1375 // successive max compactions for different reasons.
1376 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1377 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1378 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1379 total_invocations() == HeapFirstMaximumCompactionCount;
1380 if (maximum_compaction || full_cp == top_cp || interval_ended) {
1381 _maximum_compaction_gc_num = total_invocations();
1382 return sd.region_to_addr(full_cp);
1383 }
1384
1385 const size_t space_live = pointer_delta(new_top, bottom);
1386 const size_t space_used = space->used_in_words();
1387 const size_t space_capacity = space->capacity_in_words();
1388
1389 const double density = double(space_live) / double(space_capacity);
1390 const size_t min_percent_free = MarkSweepDeadRatio;
1391 const double limiter = dead_wood_limiter(density, min_percent_free);
1392 const size_t dead_wood_max = space_used - space_live;
1393 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1394 dead_wood_max);
1395
1396 if (TraceParallelOldGCDensePrefix) {
1397 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1398 "space_cap=" SIZE_FORMAT,
1399 space_live, space_used,
1400 space_capacity);
1401 tty->print_cr("dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f "
1402 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1403 density, min_percent_free, limiter,
1404 dead_wood_max, dead_wood_limit);
1405 }
1406
1407 // Locate the region with the desired amount of dead space to the left.
1408 const RegionData* const limit_cp =
1409 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1410
1411 // Scan from the first region with dead space to the limit region and find the
1412 // one with the best (largest) reclaimed ratio.
1413 double best_ratio = 0.0;
1414 const RegionData* best_cp = full_cp;
1415 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1416 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1417 if (tmp_ratio > best_ratio) {
1418 best_cp = cp;
1419 best_ratio = tmp_ratio;
1420 }
1421 }
1422
1423 return sd.region_to_addr(best_cp);
1424 }
1425
1426 void PSParallelCompact::summarize_spaces_quick()
1427 {
1428 for (unsigned int i = 0; i < last_space_id; ++i) {
1429 const MutableSpace* space = _space_info[i].space();
1430 HeapWord** nta = _space_info[i].new_top_addr();
1431 bool result = _summary_data.summarize(_space_info[i].split_info(),
1432 space->bottom(), space->top(), NULL,
1433 space->bottom(), space->end(), nta);
1434 assert(result, "space must fit into itself");
1435 _space_info[i].set_dense_prefix(space->bottom());
1436 }
1437 }
1438
1439 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1440 {
1441 HeapWord* const dense_prefix_end = dense_prefix(id);
1442 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1443 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1444 if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1445 // Only enough dead space is filled so that any remaining dead space to the
1446 // left is larger than the minimum filler object. (The remainder is filled
1447 // during the copy/update phase.)
1448 //
1449 // The size of the dead space to the right of the boundary is not a
1450 // concern, since compaction will be able to use whatever space is
1451 // available.
1452 //
1453 // Here '||' is the boundary, 'x' represents a don't care bit and a box
1454 // surrounds the space to be filled with an object.
1455 //
1456 // In the 32-bit VM, each bit represents two 32-bit words:
1457 // +---+
1458 // a) beg_bits: ... x x x | 0 | || 0 x x ...
1459 // end_bits: ... x x x | 0 | || 0 x x ...
1460 // +---+
1461 //
1462 // In the 64-bit VM, each bit represents one 64-bit word:
1463 // +------------+
1464 // b) beg_bits: ... x x x | 0 || 0 | x x ...
1465 // end_bits: ... x x 1 | 0 || 0 | x x ...
1466 // +------------+
1467 // +-------+
1468 // c) beg_bits: ... x x | 0 0 | || 0 x x ...
1469 // end_bits: ... x 1 | 0 0 | || 0 x x ...
1470 // +-------+
1471 // +-----------+
1472 // d) beg_bits: ... x | 0 0 0 | || 0 x x ...
1473 // end_bits: ... 1 | 0 0 0 | || 0 x x ...
1474 // +-----------+
1475 // +-------+
1476 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ...
1477 // end_bits: ... 0 0 | 0 0 | || 0 x x ...
1478 // +-------+
1479
1480 // Initially assume case a, c or e will apply.
1481 size_t obj_len = CollectedHeap::min_fill_size();
1482 HeapWord* obj_beg = dense_prefix_end - obj_len;
1483
1484 #ifdef _LP64
1485 if (MinObjAlignment > 1) { // object alignment > heap word size
1486 // Cases a, c or e.
1487 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1488 // Case b above.
1489 obj_beg = dense_prefix_end - 1;
1490 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1491 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1492 // Case d above.
1493 obj_beg = dense_prefix_end - 3;
1494 obj_len = 3;
1495 }
1496 #endif // #ifdef _LP64
1497
1498 CollectedHeap::fill_with_object(obj_beg, obj_len);
1499 _mark_bitmap.mark_obj(obj_beg, obj_len);
1500 _summary_data.add_obj(obj_beg, obj_len);
1501 assert(start_array(id) != NULL, "sanity");
1502 start_array(id)->allocate_block(obj_beg);
1503 }
1504 }
1505
1506 void
1507 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1508 {
1509 assert(id < last_space_id, "id out of range");
1510 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(),
1511 "should have been reset in summarize_spaces_quick()");
1512
1513 const MutableSpace* space = _space_info[id].space();
1514 if (_space_info[id].new_top() != space->bottom()) {
1515 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1516 _space_info[id].set_dense_prefix(dense_prefix_end);
1517
1518 #ifndef PRODUCT
1519 if (TraceParallelOldGCDensePrefix) {
1520 print_dense_prefix_stats("ratio", id, maximum_compaction,
1521 dense_prefix_end);
1522 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1523 print_dense_prefix_stats("density", id, maximum_compaction, addr);
1524 }
1525 #endif // #ifndef PRODUCT
1526
1527 // Recompute the summary data, taking into account the dense prefix. If
1528 // every last byte will be reclaimed, then the existing summary data which
1529 // compacts everything can be left in place.
1530 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1531 // If dead space crosses the dense prefix boundary, it is (at least
1532 // partially) filled with a dummy object, marked live and added to the
1533 // summary data. This simplifies the copy/update phase and must be done
1534 // before the final locations of objects are determined, to prevent
1535 // leaving a fragment of dead space that is too small to fill.
1536 fill_dense_prefix_end(id);
1537
1538 // Compute the destination of each Region, and thus each object.
1539 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1540 _summary_data.summarize(_space_info[id].split_info(),
1541 dense_prefix_end, space->top(), NULL,
1542 dense_prefix_end, space->end(),
1543 _space_info[id].new_top_addr());
1544 }
1545 }
1546
1547 if (log_develop_is_enabled(Trace, gc, compaction)) {
1548 const size_t region_size = ParallelCompactData::RegionSize;
1549 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1550 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1551 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1552 HeapWord* const new_top = _space_info[id].new_top();
1553 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1554 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1555 log_develop_trace(gc, compaction)(
1556 "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1557 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1558 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1559 id, space->capacity_in_words(), p2i(dense_prefix_end),
1560 dp_region, dp_words / region_size,
1561 cr_words / region_size, p2i(new_top));
1562 }
1563 }
1564
1565 #ifndef PRODUCT
1566 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1567 HeapWord* dst_beg, HeapWord* dst_end,
1568 SpaceId src_space_id,
1569 HeapWord* src_beg, HeapWord* src_end)
1570 {
1571 log_develop_trace(gc, compaction)(
1572 "Summarizing %d [%s] into %d [%s]: "
1573 "src=" PTR_FORMAT "-" PTR_FORMAT " "
1574 SIZE_FORMAT "-" SIZE_FORMAT " "
1575 "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1576 SIZE_FORMAT "-" SIZE_FORMAT,
1577 src_space_id, space_names[src_space_id],
1578 dst_space_id, space_names[dst_space_id],
1579 p2i(src_beg), p2i(src_end),
1580 _summary_data.addr_to_region_idx(src_beg),
1581 _summary_data.addr_to_region_idx(src_end),
1582 p2i(dst_beg), p2i(dst_end),
1583 _summary_data.addr_to_region_idx(dst_beg),
1584 _summary_data.addr_to_region_idx(dst_end));
1585 }
1586 #endif // #ifndef PRODUCT
1587
1588 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1589 bool maximum_compaction)
1590 {
1591 GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer);
1592
1593 #ifdef ASSERT
1594 if (TraceParallelOldGCMarkingPhase) {
1595 tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1596 "add_obj_bytes=" SIZE_FORMAT,
1597 add_obj_count, add_obj_size * HeapWordSize);
1598 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1599 "mark_bitmap_bytes=" SIZE_FORMAT,
1600 mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1601 }
1602 #endif // #ifdef ASSERT
1603
1604 // Quick summarization of each space into itself, to see how much is live.
1605 summarize_spaces_quick();
1606
1607 log_develop_trace(gc, compaction)("summary phase: after summarizing each space to self");
1608 NOT_PRODUCT(print_region_ranges());
1609 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1610
1611 // The amount of live data that will end up in old space (assuming it fits).
1612 size_t old_space_total_live = 0;
1613 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1614 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1615 _space_info[id].space()->bottom());
1616 }
1617
1618 MutableSpace* const old_space = _space_info[old_space_id].space();
1619 const size_t old_capacity = old_space->capacity_in_words();
1620 if (old_space_total_live > old_capacity) {
1621 // XXX - should also try to expand
1622 maximum_compaction = true;
1623 }
1624
1625 // Old generations.
1626 summarize_space(old_space_id, maximum_compaction);
1627
1628 // Summarize the remaining spaces in the young gen. The initial target space
1629 // is the old gen. If a space does not fit entirely into the target, then the
1630 // remainder is compacted into the space itself and that space becomes the new
1631 // target.
1632 SpaceId dst_space_id = old_space_id;
1633 HeapWord* dst_space_end = old_space->end();
1634 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1635 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1636 const MutableSpace* space = _space_info[id].space();
1637 const size_t live = pointer_delta(_space_info[id].new_top(),
1638 space->bottom());
1639 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1640
1641 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1642 SpaceId(id), space->bottom(), space->top());)
1643 if (live > 0 && live <= available) {
1644 // All the live data will fit.
1645 bool done = _summary_data.summarize(_space_info[id].split_info(),
1646 space->bottom(), space->top(),
1647 NULL,
1648 *new_top_addr, dst_space_end,
1649 new_top_addr);
1650 assert(done, "space must fit into old gen");
1651
1652 // Reset the new_top value for the space.
1653 _space_info[id].set_new_top(space->bottom());
1654 } else if (live > 0) {
1655 // Attempt to fit part of the source space into the target space.
1656 HeapWord* next_src_addr = NULL;
1657 bool done = _summary_data.summarize(_space_info[id].split_info(),
1658 space->bottom(), space->top(),
1659 &next_src_addr,
1660 *new_top_addr, dst_space_end,
1661 new_top_addr);
1662 assert(!done, "space should not fit into old gen");
1663 assert(next_src_addr != NULL, "sanity");
1664
1665 // The source space becomes the new target, so the remainder is compacted
1666 // within the space itself.
1667 dst_space_id = SpaceId(id);
1668 dst_space_end = space->end();
1669 new_top_addr = _space_info[id].new_top_addr();
1670 NOT_PRODUCT(summary_phase_msg(dst_space_id,
1671 space->bottom(), dst_space_end,
1672 SpaceId(id), next_src_addr, space->top());)
1673 done = _summary_data.summarize(_space_info[id].split_info(),
1674 next_src_addr, space->top(),
1675 NULL,
1676 space->bottom(), dst_space_end,
1677 new_top_addr);
1678 assert(done, "space must fit when compacted into itself");
1679 assert(*new_top_addr <= space->top(), "usage should not grow");
1680 }
1681 }
1682
1683 log_develop_trace(gc, compaction)("Summary_phase: after final summarization");
1684 NOT_PRODUCT(print_region_ranges());
1685 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1686 }
1687
1688 // This method should contain all heap-specific policy for invoking a full
1689 // collection. invoke_no_policy() will only attempt to compact the heap; it
1690 // will do nothing further. If we need to bail out for policy reasons, scavenge
1691 // before full gc, or any other specialized behavior, it needs to be added here.
1692 //
1693 // Note that this method should only be called from the vm_thread while at a
1694 // safepoint.
1695 //
1696 // Note that the all_soft_refs_clear flag in the collector policy
1697 // may be true because this method can be called without intervening
1698 // activity. For example when the heap space is tight and full measure
1699 // are being taken to free space.
1700 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1701 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1702 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1703 "should be in vm thread");
1704
1705 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1706 GCCause::Cause gc_cause = heap->gc_cause();
1707 assert(!heap->is_gc_active(), "not reentrant");
1708
1709 PSAdaptiveSizePolicy* policy = heap->size_policy();
1710 IsGCActiveMark mark;
1711
1712 if (ScavengeBeforeFullGC) {
1713 PSScavenge::invoke_no_policy();
1714 }
1715
1716 const bool clear_all_soft_refs =
1717 heap->collector_policy()->should_clear_all_soft_refs();
1718
1719 PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1720 maximum_heap_compaction);
1721 }
1722
1723 // This method contains no policy. You should probably
1724 // be calling invoke() instead.
1725 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1726 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1727 assert(ref_processor() != NULL, "Sanity");
1728
1729 if (GCLocker::check_active_before_gc()) {
1730 return false;
1731 }
1732
1733 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1734
1735 GCIdMark gc_id_mark;
1736 _gc_timer.register_gc_start();
1737 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
1738
1739 TimeStamp marking_start;
1740 TimeStamp compaction_start;
1741 TimeStamp collection_exit;
1742
1743 GCCause::Cause gc_cause = heap->gc_cause();
1744 PSYoungGen* young_gen = heap->young_gen();
1745 PSOldGen* old_gen = heap->old_gen();
1746 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1747
1748 // The scope of casr should end after code that can change
1749 // CollectorPolicy::_should_clear_all_soft_refs.
1750 ClearedAllSoftRefs casr(maximum_heap_compaction,
1751 heap->collector_policy());
1752
1753 if (ZapUnusedHeapArea) {
1754 // Save information needed to minimize mangling
1755 heap->record_gen_tops_before_GC();
1756 }
1757
1758 // Make sure data structures are sane, make the heap parsable, and do other
1759 // miscellaneous bookkeeping.
1760 pre_compact();
1761
1762 PreGCValues pre_gc_values(heap);
1763
1764 // Get the compaction manager reserved for the VM thread.
1765 ParCompactionManager* const vmthread_cm =
1766 ParCompactionManager::manager_array(gc_task_manager()->workers());
1767
1768 {
1769 ResourceMark rm;
1770 HandleMark hm;
1771
1772 // Set the number of GC threads to be used in this collection
1773 gc_task_manager()->set_active_gang();
1774 gc_task_manager()->task_idle_workers();
1775
1776 GCTraceCPUTime tcpu;
1777 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause, true);
1778
1779 heap->pre_full_gc_dump(&_gc_timer);
1780
1781 TraceCollectorStats tcs(counters());
1782 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
1783
1784 if (TraceOldGenTime) accumulated_time()->start();
1785
1786 // Let the size policy know we're starting
1787 size_policy->major_collection_begin();
1788
1789 CodeCache::gc_prologue();
1790
1791 #if defined(COMPILER2) || INCLUDE_JVMCI
1792 DerivedPointerTable::clear();
1793 #endif
1794
1795 ref_processor()->enable_discovery();
1796 ref_processor()->setup_policy(maximum_heap_compaction);
1797
1798 bool marked_for_unloading = false;
1799
1800 marking_start.update();
1801 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer);
1802
1803 bool max_on_system_gc = UseMaximumCompactionOnSystemGC
1804 && GCCause::is_user_requested_gc(gc_cause);
1805 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
1806
1807 #if defined(COMPILER2) || INCLUDE_JVMCI
1808 assert(DerivedPointerTable::is_active(), "Sanity");
1809 DerivedPointerTable::set_active(false);
1810 #endif
1811
1812 // adjust_roots() updates Universe::_intArrayKlassObj which is
1813 // needed by the compaction for filling holes in the dense prefix.
1814 adjust_roots(vmthread_cm);
1815
1816 compaction_start.update();
1817 compact();
1818
1819 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
1820 // done before resizing.
1821 post_compact();
1822
1823 // Let the size policy know we're done
1824 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
1825
1826 if (UseAdaptiveSizePolicy) {
1827 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
1828 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
1829 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
1830
1831 // Don't check if the size_policy is ready here. Let
1832 // the size_policy check that internally.
1833 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
1834 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
1835 // Swap the survivor spaces if from_space is empty. The
1836 // resize_young_gen() called below is normally used after
1837 // a successful young GC and swapping of survivor spaces;
1838 // otherwise, it will fail to resize the young gen with
1839 // the current implementation.
1840 if (young_gen->from_space()->is_empty()) {
1841 young_gen->from_space()->clear(SpaceDecorator::Mangle);
1842 young_gen->swap_spaces();
1843 }
1844
1845 // Calculate optimal free space amounts
1846 assert(young_gen->max_size() >
1847 young_gen->from_space()->capacity_in_bytes() +
1848 young_gen->to_space()->capacity_in_bytes(),
1849 "Sizes of space in young gen are out-of-bounds");
1850
1851 size_t young_live = young_gen->used_in_bytes();
1852 size_t eden_live = young_gen->eden_space()->used_in_bytes();
1853 size_t old_live = old_gen->used_in_bytes();
1854 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
1855 size_t max_old_gen_size = old_gen->max_gen_size();
1856 size_t max_eden_size = young_gen->max_size() -
1857 young_gen->from_space()->capacity_in_bytes() -
1858 young_gen->to_space()->capacity_in_bytes();
1859
1860 // Used for diagnostics
1861 size_policy->clear_generation_free_space_flags();
1862
1863 size_policy->compute_generations_free_space(young_live,
1864 eden_live,
1865 old_live,
1866 cur_eden,
1867 max_old_gen_size,
1868 max_eden_size,
1869 true /* full gc*/);
1870
1871 size_policy->check_gc_overhead_limit(young_live,
1872 eden_live,
1873 max_old_gen_size,
1874 max_eden_size,
1875 true /* full gc*/,
1876 gc_cause,
1877 heap->collector_policy());
1878
1879 size_policy->decay_supplemental_growth(true /* full gc*/);
1880
1881 heap->resize_old_gen(
1882 size_policy->calculated_old_free_size_in_bytes());
1883
1884 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
1885 size_policy->calculated_survivor_size_in_bytes());
1886 }
1887
1888 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
1889 }
1890
1891 if (UsePerfData) {
1892 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
1893 counters->update_counters();
1894 counters->update_old_capacity(old_gen->capacity_in_bytes());
1895 counters->update_young_capacity(young_gen->capacity_in_bytes());
1896 }
1897
1898 heap->resize_all_tlabs();
1899
1900 // Resize the metaspace capacity after a collection
1901 MetaspaceGC::compute_new_size();
1902
1903 if (TraceOldGenTime) {
1904 accumulated_time()->stop();
1905 }
1906
1907 young_gen->print_used_change(pre_gc_values.young_gen_used());
1908 old_gen->print_used_change(pre_gc_values.old_gen_used());
1909 MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used());
1910
1911 // Track memory usage and detect low memory
1912 MemoryService::track_memory_usage();
1913 heap->update_counters();
1914 gc_task_manager()->release_idle_workers();
1915
1916 heap->post_full_gc_dump(&_gc_timer);
1917 }
1918
1919 #ifdef ASSERT
1920 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
1921 ParCompactionManager* const cm =
1922 ParCompactionManager::manager_array(int(i));
1923 assert(cm->marking_stack()->is_empty(), "should be empty");
1924 assert(cm->region_stack()->is_empty(), "Region stack " SIZE_FORMAT " is not empty", i);
1925 }
1926 #endif // ASSERT
1927
1928 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1929 HandleMark hm; // Discard invalid handles created during verification
1930 Universe::verify("After GC");
1931 }
1932
1933 // Re-verify object start arrays
1934 if (VerifyObjectStartArray &&
1935 VerifyAfterGC) {
1936 old_gen->verify_object_start_array();
1937 }
1938
1939 if (ZapUnusedHeapArea) {
1940 old_gen->object_space()->check_mangled_unused_area_complete();
1941 }
1942
1943 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1944
1945 collection_exit.update();
1946
1947 heap->print_heap_after_gc();
1948 heap->trace_heap_after_gc(&_gc_tracer);
1949
1950 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT,
1951 marking_start.ticks(), compaction_start.ticks(),
1952 collection_exit.ticks());
1953 gc_task_manager()->print_task_time_stamps();
1954
1955 #ifdef TRACESPINNING
1956 ParallelTaskTerminator::print_termination_counts();
1957 #endif
1958
1959 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
1960
1961 _gc_timer.register_gc_end();
1962
1963 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
1964 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
1965
1966 return true;
1967 }
1968
1969 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
1970 PSYoungGen* young_gen,
1971 PSOldGen* old_gen) {
1972 MutableSpace* const eden_space = young_gen->eden_space();
1973 assert(!eden_space->is_empty(), "eden must be non-empty");
1974 assert(young_gen->virtual_space()->alignment() ==
1975 old_gen->virtual_space()->alignment(), "alignments do not match");
1976
1977 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
1978 return false;
1979 }
1980
1981 // Both generations must be completely committed.
1982 if (young_gen->virtual_space()->uncommitted_size() != 0) {
1983 return false;
1984 }
1985 if (old_gen->virtual_space()->uncommitted_size() != 0) {
1986 return false;
1987 }
1988
1989 // Figure out how much to take from eden. Include the average amount promoted
1990 // in the total; otherwise the next young gen GC will simply bail out to a
1991 // full GC.
1992 const size_t alignment = old_gen->virtual_space()->alignment();
1993 const size_t eden_used = eden_space->used_in_bytes();
1994 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
1995 const size_t absorb_size = align_up(eden_used + promoted, alignment);
1996 const size_t eden_capacity = eden_space->capacity_in_bytes();
1997
1998 if (absorb_size >= eden_capacity) {
1999 return false; // Must leave some space in eden.
2000 }
2001
2002 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2003 if (new_young_size < young_gen->min_gen_size()) {
2004 return false; // Respect young gen minimum size.
2005 }
2006
2007 log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K: "
2008 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2009 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2010 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2011 absorb_size / K,
2012 eden_capacity / K, (eden_capacity - absorb_size) / K,
2013 young_gen->from_space()->used_in_bytes() / K,
2014 young_gen->to_space()->used_in_bytes() / K,
2015 young_gen->capacity_in_bytes() / K, new_young_size / K);
2016
2017 // Fill the unused part of the old gen.
2018 MutableSpace* const old_space = old_gen->object_space();
2019 HeapWord* const unused_start = old_space->top();
2020 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2021
2022 if (unused_words > 0) {
2023 if (unused_words < CollectedHeap::min_fill_size()) {
2024 return false; // If the old gen cannot be filled, must give up.
2025 }
2026 CollectedHeap::fill_with_objects(unused_start, unused_words);
2027 }
2028
2029 // Take the live data from eden and set both top and end in the old gen to
2030 // eden top. (Need to set end because reset_after_change() mangles the region
2031 // from end to virtual_space->high() in debug builds).
2032 HeapWord* const new_top = eden_space->top();
2033 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2034 absorb_size);
2035 young_gen->reset_after_change();
2036 old_space->set_top(new_top);
2037 old_space->set_end(new_top);
2038 old_gen->reset_after_change();
2039
2040 // Update the object start array for the filler object and the data from eden.
2041 ObjectStartArray* const start_array = old_gen->start_array();
2042 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2043 start_array->allocate_block(p);
2044 }
2045
2046 // Could update the promoted average here, but it is not typically updated at
2047 // full GCs and the value to use is unclear. Something like
2048 //
2049 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2050
2051 size_policy->set_bytes_absorbed_from_eden(absorb_size);
2052 return true;
2053 }
2054
2055 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2056 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2057 "shouldn't return NULL");
2058 return ParallelScavengeHeap::gc_task_manager();
2059 }
2060
2061 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2062 bool maximum_heap_compaction,
2063 ParallelOldTracer *gc_tracer) {
2064 // Recursively traverse all live objects and mark them
2065 GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer);
2066
2067 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2068 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2069 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2070 TaskQueueSetSuper* qset = ParCompactionManager::stack_array();
2071 ParallelTaskTerminator terminator(active_gc_threads, qset);
2072
2073 ParCompactionManager::MarkAndPushClosure mark_and_push_closure(cm);
2074 ParCompactionManager::FollowStackClosure follow_stack_closure(cm);
2075
2076 // Need new claim bits before marking starts.
2077 ClassLoaderDataGraph::clear_claimed_marks();
2078
2079 {
2080 GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer);
2081
2082 ParallelScavengeHeap::ParStrongRootsScope psrs;
2083
2084 GCTaskQueue* q = GCTaskQueue::create();
2085
2086 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2087 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2088 // We scan the thread roots in parallel
2089 Threads::create_thread_roots_marking_tasks(q);
2090 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2091 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
2092 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2093 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2094 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data));
2095 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2096 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2097
2098 if (active_gc_threads > 1) {
2099 for (uint j = 0; j < active_gc_threads; j++) {
2100 q->enqueue(new StealMarkingTask(&terminator));
2101 }
2102 }
2103
2104 gc_task_manager()->execute_and_wait(q);
2105 }
2106
2107 // Process reference objects found during marking
2108 {
2109 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
2110
2111 ReferenceProcessorStats stats;
2112 ReferenceProcessorPhaseTimes pt(&_gc_timer,
2113 ref_processor()->num_q(),
2114 ref_processor()->processing_is_mt());
2115 if (ref_processor()->processing_is_mt()) {
2116 RefProcTaskExecutor task_executor;
2117 stats = ref_processor()->process_discovered_references(
2118 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2119 &task_executor, &pt);
2120 } else {
2121 stats = ref_processor()->process_discovered_references(
2122 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
2123 &pt);
2124 }
2125
2126 gc_tracer->report_gc_reference_stats(stats);
2127 pt.print_all_references();
2128 }
2129
2130 // This is the point where the entire marking should have completed.
2131 assert(cm->marking_stacks_empty(), "Marking should have completed");
2132
2133 {
2134 GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer);
2135
2136 // Follow system dictionary roots and unload classes.
2137 bool purged_class = SystemDictionary::do_unloading(is_alive_closure(), &_gc_timer);
2138
2139 // Unload nmethods.
2140 CodeCache::do_unloading(is_alive_closure(), purged_class);
2141
2142 // Prune dead klasses from subklass/sibling/implementor lists.
2143 Klass::clean_weak_klass_links(is_alive_closure());
2144 }
2145
2146 {
2147 GCTraceTime(Debug, gc, phases) t("Scrub String Table", &_gc_timer);
2148 // Delete entries for dead interned strings.
2149 StringTable::unlink(is_alive_closure());
2150 }
2151
2152 {
2153 GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", &_gc_timer);
2154 // Clean up unreferenced symbols in symbol table.
2155 SymbolTable::unlink();
2156 }
2157
2158 _gc_tracer.report_object_count_after_gc(is_alive_closure());
2159 }
2160
2161 void PSParallelCompact::adjust_roots(ParCompactionManager* cm) {
2162 // Adjust the pointers to reflect the new locations
2163 GCTraceTime(Info, gc, phases) tm("Adjust Roots", &_gc_timer);
2164
2165 // Need new claim bits when tracing through and adjusting pointers.
2166 ClassLoaderDataGraph::clear_claimed_marks();
2167
2168 PSParallelCompact::AdjustPointerClosure oop_closure(cm);
2169 PSParallelCompact::AdjustKlassClosure klass_closure(cm);
2170
2171 // General strong roots.
2172 Universe::oops_do(&oop_closure);
2173 JNIHandles::oops_do(&oop_closure); // Global (strong) JNI handles
2174 Threads::oops_do(&oop_closure, NULL);
2175 ObjectSynchronizer::oops_do(&oop_closure);
2176 FlatProfiler::oops_do(&oop_closure);
2177 Management::oops_do(&oop_closure);
2178 JvmtiExport::oops_do(&oop_closure);
2179 SystemDictionary::oops_do(&oop_closure);
2180 ClassLoaderDataGraph::oops_do(&oop_closure, &klass_closure, true);
2181
2182 // Now adjust pointers in remaining weak roots. (All of which should
2183 // have been cleared if they pointed to non-surviving objects.)
2184 // Global (weak) JNI handles
2185 JNIHandles::weak_oops_do(&oop_closure);
2186
2187 CodeBlobToOopClosure adjust_from_blobs(&oop_closure, CodeBlobToOopClosure::FixRelocations);
2188 CodeCache::blobs_do(&adjust_from_blobs);
2189 AOTLoader::oops_do(&oop_closure);
2190 StringTable::oops_do(&oop_closure);
2191 ref_processor()->weak_oops_do(&oop_closure);
2192 // Roots were visited so references into the young gen in roots
2193 // may have been scanned. Process them also.
2194 // Should the reference processor have a span that excludes
2195 // young gen objects?
2196 PSScavenge::reference_processor()->weak_oops_do(&oop_closure);
2197 }
2198
2199 // Helper class to print 8 region numbers per line and then print the total at the end.
2200 class FillableRegionLogger : public StackObj {
2201 private:
2202 Log(gc, compaction) log;
2203 static const int LineLength = 8;
2204 size_t _regions[LineLength];
2205 int _next_index;
2206 bool _enabled;
2207 size_t _total_regions;
2208 public:
2209 FillableRegionLogger() : _next_index(0), _total_regions(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)) { }
2210 ~FillableRegionLogger() {
2211 log.trace(SIZE_FORMAT " initially fillable regions", _total_regions);
2212 }
2213
2214 void print_line() {
2215 if (!_enabled || _next_index == 0) {
2216 return;
2217 }
2218 FormatBuffer<> line("Fillable: ");
2219 for (int i = 0; i < _next_index; i++) {
2220 line.append(" " SIZE_FORMAT_W(7), _regions[i]);
2221 }
2222 log.trace("%s", line.buffer());
2223 _next_index = 0;
2224 }
2225
2226 void handle(size_t region) {
2227 if (!_enabled) {
2228 return;
2229 }
2230 _regions[_next_index++] = region;
2231 if (_next_index == LineLength) {
2232 print_line();
2233 }
2234 _total_regions++;
2235 }
2236 };
2237
2238 void PSParallelCompact::prepare_region_draining_tasks(GCTaskQueue* q,
2239 uint parallel_gc_threads)
2240 {
2241 GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer);
2242
2243 // Find the threads that are active
2244 unsigned int which = 0;
2245
2246 // Find all regions that are available (can be filled immediately) and
2247 // distribute them to the thread stacks. The iteration is done in reverse
2248 // order (high to low) so the regions will be removed in ascending order.
2249
2250 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2251
2252 which = 0;
2253 // id + 1 is used to test termination so unsigned can
2254 // be used with an old_space_id == 0.
2255 FillableRegionLogger region_logger;
2256 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2257 SpaceInfo* const space_info = _space_info + id;
2258 MutableSpace* const space = space_info->space();
2259 HeapWord* const new_top = space_info->new_top();
2260
2261 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2262 const size_t end_region =
2263 sd.addr_to_region_idx(sd.region_align_up(new_top));
2264
2265 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2266 if (sd.region(cur)->claim_unsafe()) {
2267 ParCompactionManager* cm = ParCompactionManager::manager_array(which);
2268 cm->region_stack()->push(cur);
2269 region_logger.handle(cur);
2270 // Assign regions to tasks in round-robin fashion.
2271 if (++which == parallel_gc_threads) {
2272 which = 0;
2273 }
2274 }
2275 }
2276 region_logger.print_line();
2277 }
2278 }
2279
2280 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2281
2282 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2283 uint parallel_gc_threads) {
2284 GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer);
2285
2286 ParallelCompactData& sd = PSParallelCompact::summary_data();
2287
2288 // Iterate over all the spaces adding tasks for updating
2289 // regions in the dense prefix. Assume that 1 gc thread
2290 // will work on opening the gaps and the remaining gc threads
2291 // will work on the dense prefix.
2292 unsigned int space_id;
2293 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2294 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2295 const MutableSpace* const space = _space_info[space_id].space();
2296
2297 if (dense_prefix_end == space->bottom()) {
2298 // There is no dense prefix for this space.
2299 continue;
2300 }
2301
2302 // The dense prefix is before this region.
2303 size_t region_index_end_dense_prefix =
2304 sd.addr_to_region_idx(dense_prefix_end);
2305 RegionData* const dense_prefix_cp =
2306 sd.region(region_index_end_dense_prefix);
2307 assert(dense_prefix_end == space->end() ||
2308 dense_prefix_cp->available() ||
2309 dense_prefix_cp->claimed(),
2310 "The region after the dense prefix should always be ready to fill");
2311
2312 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2313
2314 // Is there dense prefix work?
2315 size_t total_dense_prefix_regions =
2316 region_index_end_dense_prefix - region_index_start;
2317 // How many regions of the dense prefix should be given to
2318 // each thread?
2319 if (total_dense_prefix_regions > 0) {
2320 uint tasks_for_dense_prefix = 1;
2321 if (total_dense_prefix_regions <=
2322 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2323 // Don't over partition. This assumes that
2324 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2325 // so there are not many regions to process.
2326 tasks_for_dense_prefix = parallel_gc_threads;
2327 } else {
2328 // Over partition
2329 tasks_for_dense_prefix = parallel_gc_threads *
2330 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2331 }
2332 size_t regions_per_thread = total_dense_prefix_regions /
2333 tasks_for_dense_prefix;
2334 // Give each thread at least 1 region.
2335 if (regions_per_thread == 0) {
2336 regions_per_thread = 1;
2337 }
2338
2339 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2340 if (region_index_start >= region_index_end_dense_prefix) {
2341 break;
2342 }
2343 // region_index_end is not processed
2344 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2345 region_index_end_dense_prefix);
2346 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2347 region_index_start,
2348 region_index_end));
2349 region_index_start = region_index_end;
2350 }
2351 }
2352 // This gets any part of the dense prefix that did not
2353 // fit evenly.
2354 if (region_index_start < region_index_end_dense_prefix) {
2355 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2356 region_index_start,
2357 region_index_end_dense_prefix));
2358 }
2359 }
2360 }
2361
2362 void PSParallelCompact::enqueue_region_stealing_tasks(
2363 GCTaskQueue* q,
2364 ParallelTaskTerminator* terminator_ptr,
2365 uint parallel_gc_threads) {
2366 GCTraceTime(Trace, gc, phases) tm("Steal Task Setup", &_gc_timer);
2367
2368 // Once a thread has drained it's stack, it should try to steal regions from
2369 // other threads.
2370 for (uint j = 0; j < parallel_gc_threads; j++) {
2371 q->enqueue(new CompactionWithStealingTask(terminator_ptr));
2372 }
2373 }
2374
2375 #ifdef ASSERT
2376 // Write a histogram of the number of times the block table was filled for a
2377 // region.
2378 void PSParallelCompact::write_block_fill_histogram()
2379 {
2380 if (!log_develop_is_enabled(Trace, gc, compaction)) {
2381 return;
2382 }
2383
2384 Log(gc, compaction) log;
2385 ResourceMark rm;
2386 LogStream ls(log.trace());
2387 outputStream* out = &ls;
2388
2389 typedef ParallelCompactData::RegionData rd_t;
2390 ParallelCompactData& sd = summary_data();
2391
2392 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2393 MutableSpace* const spc = _space_info[id].space();
2394 if (spc->bottom() != spc->top()) {
2395 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
2396 HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
2397 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
2398
2399 size_t histo[5] = { 0, 0, 0, 0, 0 };
2400 const size_t histo_len = sizeof(histo) / sizeof(size_t);
2401 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
2402
2403 for (const rd_t* cur = beg; cur < end; ++cur) {
2404 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
2405 }
2406 out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
2407 for (size_t i = 0; i < histo_len; ++i) {
2408 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
2409 histo[i], 100.0 * histo[i] / region_cnt);
2410 }
2411 out->cr();
2412 }
2413 }
2414 }
2415 #endif // #ifdef ASSERT
2416
2417 void PSParallelCompact::compact() {
2418 GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer);
2419
2420 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2421 PSOldGen* old_gen = heap->old_gen();
2422 old_gen->start_array()->reset();
2423 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2424 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2425 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2426 ParallelTaskTerminator terminator(active_gc_threads, qset);
2427
2428 GCTaskQueue* q = GCTaskQueue::create();
2429 prepare_region_draining_tasks(q, active_gc_threads);
2430 enqueue_dense_prefix_tasks(q, active_gc_threads);
2431 enqueue_region_stealing_tasks(q, &terminator, active_gc_threads);
2432
2433 {
2434 GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer);
2435
2436 gc_task_manager()->execute_and_wait(q);
2437
2438 #ifdef ASSERT
2439 // Verify that all regions have been processed before the deferred updates.
2440 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2441 verify_complete(SpaceId(id));
2442 }
2443 #endif
2444 }
2445
2446 {
2447 // Update the deferred objects, if any. Any compaction manager can be used.
2448 GCTraceTime(Trace, gc, phases) tm("Deferred Updates", &_gc_timer);
2449 ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2450 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2451 update_deferred_objects(cm, SpaceId(id));
2452 }
2453 }
2454
2455 DEBUG_ONLY(write_block_fill_histogram());
2456 }
2457
2458 #ifdef ASSERT
2459 void PSParallelCompact::verify_complete(SpaceId space_id) {
2460 // All Regions between space bottom() to new_top() should be marked as filled
2461 // and all Regions between new_top() and top() should be available (i.e.,
2462 // should have been emptied).
2463 ParallelCompactData& sd = summary_data();
2464 SpaceInfo si = _space_info[space_id];
2465 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2466 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2467 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2468 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2469 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2470
2471 bool issued_a_warning = false;
2472
2473 size_t cur_region;
2474 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2475 const RegionData* const c = sd.region(cur_region);
2476 if (!c->completed()) {
2477 log_warning(gc)("region " SIZE_FORMAT " not filled: destination_count=%u",
2478 cur_region, c->destination_count());
2479 issued_a_warning = true;
2480 }
2481 }
2482
2483 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2484 const RegionData* const c = sd.region(cur_region);
2485 if (!c->available()) {
2486 log_warning(gc)("region " SIZE_FORMAT " not empty: destination_count=%u",
2487 cur_region, c->destination_count());
2488 issued_a_warning = true;
2489 }
2490 }
2491
2492 if (issued_a_warning) {
2493 print_region_ranges();
2494 }
2495 }
2496 #endif // #ifdef ASSERT
2497
2498 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) {
2499 _start_array->allocate_block(addr);
2500 compaction_manager()->update_contents(oop(addr));
2501 }
2502
2503 // Update interior oops in the ranges of regions [beg_region, end_region).
2504 void
2505 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2506 SpaceId space_id,
2507 size_t beg_region,
2508 size_t end_region) {
2509 ParallelCompactData& sd = summary_data();
2510 ParMarkBitMap* const mbm = mark_bitmap();
2511
2512 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2513 HeapWord* const end_addr = sd.region_to_addr(end_region);
2514 assert(beg_region <= end_region, "bad region range");
2515 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2516
2517 #ifdef ASSERT
2518 // Claim the regions to avoid triggering an assert when they are marked as
2519 // filled.
2520 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2521 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2522 }
2523 #endif // #ifdef ASSERT
2524
2525 if (beg_addr != space(space_id)->bottom()) {
2526 // Find the first live object or block of dead space that *starts* in this
2527 // range of regions. If a partial object crosses onto the region, skip it;
2528 // it will be marked for 'deferred update' when the object head is
2529 // processed. If dead space crosses onto the region, it is also skipped; it
2530 // will be filled when the prior region is processed. If neither of those
2531 // apply, the first word in the region is the start of a live object or dead
2532 // space.
2533 assert(beg_addr > space(space_id)->bottom(), "sanity");
2534 const RegionData* const cp = sd.region(beg_region);
2535 if (cp->partial_obj_size() != 0) {
2536 beg_addr = sd.partial_obj_end(beg_region);
2537 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2538 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2539 }
2540 }
2541
2542 if (beg_addr < end_addr) {
2543 // A live object or block of dead space starts in this range of Regions.
2544 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2545
2546 // Create closures and iterate.
2547 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2548 FillClosure fill_closure(cm, space_id);
2549 ParMarkBitMap::IterationStatus status;
2550 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2551 dense_prefix_end);
2552 if (status == ParMarkBitMap::incomplete) {
2553 update_closure.do_addr(update_closure.source());
2554 }
2555 }
2556
2557 // Mark the regions as filled.
2558 RegionData* const beg_cp = sd.region(beg_region);
2559 RegionData* const end_cp = sd.region(end_region);
2560 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2561 cp->set_completed();
2562 }
2563 }
2564
2565 // Return the SpaceId for the space containing addr. If addr is not in the
2566 // heap, last_space_id is returned. In debug mode it expects the address to be
2567 // in the heap and asserts such.
2568 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2569 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
2570
2571 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2572 if (_space_info[id].space()->contains(addr)) {
2573 return SpaceId(id);
2574 }
2575 }
2576
2577 assert(false, "no space contains the addr");
2578 return last_space_id;
2579 }
2580
2581 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2582 SpaceId id) {
2583 assert(id < last_space_id, "bad space id");
2584
2585 ParallelCompactData& sd = summary_data();
2586 const SpaceInfo* const space_info = _space_info + id;
2587 ObjectStartArray* const start_array = space_info->start_array();
2588
2589 const MutableSpace* const space = space_info->space();
2590 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2591 HeapWord* const beg_addr = space_info->dense_prefix();
2592 HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2593
2594 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2595 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2596 const RegionData* cur_region;
2597 for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2598 HeapWord* const addr = cur_region->deferred_obj_addr();
2599 if (addr != NULL) {
2600 if (start_array != NULL) {
2601 start_array->allocate_block(addr);
2602 }
2603 cm->update_contents(oop(addr));
2604 assert(oop(addr)->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(addr)));
2605 }
2606 }
2607 }
2608
2609 // Skip over count live words starting from beg, and return the address of the
2610 // next live word. Unless marked, the word corresponding to beg is assumed to
2611 // be dead. Callers must either ensure beg does not correspond to the middle of
2612 // an object, or account for those live words in some other way. Callers must
2613 // also ensure that there are enough live words in the range [beg, end) to skip.
2614 HeapWord*
2615 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2616 {
2617 assert(count > 0, "sanity");
2618
2619 ParMarkBitMap* m = mark_bitmap();
2620 idx_t bits_to_skip = m->words_to_bits(count);
2621 idx_t cur_beg = m->addr_to_bit(beg);
2622 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
2623
2624 do {
2625 cur_beg = m->find_obj_beg(cur_beg, search_end);
2626 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2627 const size_t obj_bits = cur_end - cur_beg + 1;
2628 if (obj_bits > bits_to_skip) {
2629 return m->bit_to_addr(cur_beg + bits_to_skip);
2630 }
2631 bits_to_skip -= obj_bits;
2632 cur_beg = cur_end + 1;
2633 } while (bits_to_skip > 0);
2634
2635 // Skipping the desired number of words landed just past the end of an object.
2636 // Find the start of the next object.
2637 cur_beg = m->find_obj_beg(cur_beg, search_end);
2638 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2639 return m->bit_to_addr(cur_beg);
2640 }
2641
2642 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2643 SpaceId src_space_id,
2644 size_t src_region_idx)
2645 {
2646 assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2647
2648 const SplitInfo& split_info = _space_info[src_space_id].split_info();
2649 if (split_info.dest_region_addr() == dest_addr) {
2650 // The partial object ending at the split point contains the first word to
2651 // be copied to dest_addr.
2652 return split_info.first_src_addr();
2653 }
2654
2655 const ParallelCompactData& sd = summary_data();
2656 ParMarkBitMap* const bitmap = mark_bitmap();
2657 const size_t RegionSize = ParallelCompactData::RegionSize;
2658
2659 assert(sd.is_region_aligned(dest_addr), "not aligned");
2660 const RegionData* const src_region_ptr = sd.region(src_region_idx);
2661 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2662 HeapWord* const src_region_destination = src_region_ptr->destination();
2663
2664 assert(dest_addr >= src_region_destination, "wrong src region");
2665 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2666
2667 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2668 HeapWord* const src_region_end = src_region_beg + RegionSize;
2669
2670 HeapWord* addr = src_region_beg;
2671 if (dest_addr == src_region_destination) {
2672 // Return the first live word in the source region.
2673 if (partial_obj_size == 0) {
2674 addr = bitmap->find_obj_beg(addr, src_region_end);
2675 assert(addr < src_region_end, "no objects start in src region");
2676 }
2677 return addr;
2678 }
2679
2680 // Must skip some live data.
2681 size_t words_to_skip = dest_addr - src_region_destination;
2682 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2683
2684 if (partial_obj_size >= words_to_skip) {
2685 // All the live words to skip are part of the partial object.
2686 addr += words_to_skip;
2687 if (partial_obj_size == words_to_skip) {
2688 // Find the first live word past the partial object.
2689 addr = bitmap->find_obj_beg(addr, src_region_end);
2690 assert(addr < src_region_end, "wrong src region");
2691 }
2692 return addr;
2693 }
2694
2695 // Skip over the partial object (if any).
2696 if (partial_obj_size != 0) {
2697 words_to_skip -= partial_obj_size;
2698 addr += partial_obj_size;
2699 }
2700
2701 // Skip over live words due to objects that start in the region.
2702 addr = skip_live_words(addr, src_region_end, words_to_skip);
2703 assert(addr < src_region_end, "wrong src region");
2704 return addr;
2705 }
2706
2707 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2708 SpaceId src_space_id,
2709 size_t beg_region,
2710 HeapWord* end_addr)
2711 {
2712 ParallelCompactData& sd = summary_data();
2713
2714 #ifdef ASSERT
2715 MutableSpace* const src_space = _space_info[src_space_id].space();
2716 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2717 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2718 "src_space_id does not match beg_addr");
2719 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2720 "src_space_id does not match end_addr");
2721 #endif // #ifdef ASSERT
2722
2723 RegionData* const beg = sd.region(beg_region);
2724 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2725
2726 // Regions up to new_top() are enqueued if they become available.
2727 HeapWord* const new_top = _space_info[src_space_id].new_top();
2728 RegionData* const enqueue_end =
2729 sd.addr_to_region_ptr(sd.region_align_up(new_top));
2730
2731 for (RegionData* cur = beg; cur < end; ++cur) {
2732 assert(cur->data_size() > 0, "region must have live data");
2733 cur->decrement_destination_count();
2734 if (cur < enqueue_end && cur->available() && cur->claim()) {
2735 cm->push_region(sd.region(cur));
2736 }
2737 }
2738 }
2739
2740 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2741 SpaceId& src_space_id,
2742 HeapWord*& src_space_top,
2743 HeapWord* end_addr)
2744 {
2745 typedef ParallelCompactData::RegionData RegionData;
2746
2747 ParallelCompactData& sd = PSParallelCompact::summary_data();
2748 const size_t region_size = ParallelCompactData::RegionSize;
2749
2750 size_t src_region_idx = 0;
2751
2752 // Skip empty regions (if any) up to the top of the space.
2753 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2754 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2755 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2756 const RegionData* const top_region_ptr =
2757 sd.addr_to_region_ptr(top_aligned_up);
2758 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2759 ++src_region_ptr;
2760 }
2761
2762 if (src_region_ptr < top_region_ptr) {
2763 // The next source region is in the current space. Update src_region_idx
2764 // and the source address to match src_region_ptr.
2765 src_region_idx = sd.region(src_region_ptr);
2766 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
2767 if (src_region_addr > closure.source()) {
2768 closure.set_source(src_region_addr);
2769 }
2770 return src_region_idx;
2771 }
2772
2773 // Switch to a new source space and find the first non-empty region.
2774 unsigned int space_id = src_space_id + 1;
2775 assert(space_id < last_space_id, "not enough spaces");
2776
2777 HeapWord* const destination = closure.destination();
2778
2779 do {
2780 MutableSpace* space = _space_info[space_id].space();
2781 HeapWord* const bottom = space->bottom();
2782 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
2783
2784 // Iterate over the spaces that do not compact into themselves.
2785 if (bottom_cp->destination() != bottom) {
2786 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
2787 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
2788
2789 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
2790 if (src_cp->live_obj_size() > 0) {
2791 // Found it.
2792 assert(src_cp->destination() == destination,
2793 "first live obj in the space must match the destination");
2794 assert(src_cp->partial_obj_size() == 0,
2795 "a space cannot begin with a partial obj");
2796
2797 src_space_id = SpaceId(space_id);
2798 src_space_top = space->top();
2799 const size_t src_region_idx = sd.region(src_cp);
2800 closure.set_source(sd.region_to_addr(src_region_idx));
2801 return src_region_idx;
2802 } else {
2803 assert(src_cp->data_size() == 0, "sanity");
2804 }
2805 }
2806 }
2807 } while (++space_id < last_space_id);
2808
2809 assert(false, "no source region was found");
2810 return 0;
2811 }
2812
2813 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
2814 {
2815 typedef ParMarkBitMap::IterationStatus IterationStatus;
2816 const size_t RegionSize = ParallelCompactData::RegionSize;
2817 ParMarkBitMap* const bitmap = mark_bitmap();
2818 ParallelCompactData& sd = summary_data();
2819 RegionData* const region_ptr = sd.region(region_idx);
2820
2821 // Get the items needed to construct the closure.
2822 HeapWord* dest_addr = sd.region_to_addr(region_idx);
2823 SpaceId dest_space_id = space_id(dest_addr);
2824 ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
2825 HeapWord* new_top = _space_info[dest_space_id].new_top();
2826 assert(dest_addr < new_top, "sanity");
2827 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
2828
2829 // Get the source region and related info.
2830 size_t src_region_idx = region_ptr->source_region();
2831 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2832 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2833
2834 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
2835 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2836
2837 // Adjust src_region_idx to prepare for decrementing destination counts (the
2838 // destination count is not decremented when a region is copied to itself).
2839 if (src_region_idx == region_idx) {
2840 src_region_idx += 1;
2841 }
2842
2843 if (bitmap->is_unmarked(closure.source())) {
2844 // The first source word is in the middle of an object; copy the remainder
2845 // of the object or as much as will fit. The fact that pointer updates were
2846 // deferred will be noted when the object header is processed.
2847 HeapWord* const old_src_addr = closure.source();
2848 closure.copy_partial_obj();
2849 if (closure.is_full()) {
2850 decrement_destination_counts(cm, src_space_id, src_region_idx,
2851 closure.source());
2852 region_ptr->set_deferred_obj_addr(NULL);
2853 region_ptr->set_completed();
2854 return;
2855 }
2856
2857 HeapWord* const end_addr = sd.region_align_down(closure.source());
2858 if (sd.region_align_down(old_src_addr) != end_addr) {
2859 // The partial object was copied from more than one source region.
2860 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2861
2862 // Move to the next source region, possibly switching spaces as well. All
2863 // args except end_addr may be modified.
2864 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2865 end_addr);
2866 }
2867 }
2868
2869 do {
2870 HeapWord* const cur_addr = closure.source();
2871 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2872 src_space_top);
2873 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
2874
2875 if (status == ParMarkBitMap::incomplete) {
2876 // The last obj that starts in the source region does not end in the
2877 // region.
2878 assert(closure.source() < end_addr, "sanity");
2879 HeapWord* const obj_beg = closure.source();
2880 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
2881 src_space_top);
2882 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
2883 if (obj_end < range_end) {
2884 // The end was found; the entire object will fit.
2885 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
2886 assert(status != ParMarkBitMap::would_overflow, "sanity");
2887 } else {
2888 // The end was not found; the object will not fit.
2889 assert(range_end < src_space_top, "obj cannot cross space boundary");
2890 status = ParMarkBitMap::would_overflow;
2891 }
2892 }
2893
2894 if (status == ParMarkBitMap::would_overflow) {
2895 // The last object did not fit. Note that interior oop updates were
2896 // deferred, then copy enough of the object to fill the region.
2897 region_ptr->set_deferred_obj_addr(closure.destination());
2898 status = closure.copy_until_full(); // copies from closure.source()
2899
2900 decrement_destination_counts(cm, src_space_id, src_region_idx,
2901 closure.source());
2902 region_ptr->set_completed();
2903 return;
2904 }
2905
2906 if (status == ParMarkBitMap::full) {
2907 decrement_destination_counts(cm, src_space_id, src_region_idx,
2908 closure.source());
2909 region_ptr->set_deferred_obj_addr(NULL);
2910 region_ptr->set_completed();
2911 return;
2912 }
2913
2914 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2915
2916 // Move to the next source region, possibly switching spaces as well. All
2917 // args except end_addr may be modified.
2918 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2919 end_addr);
2920 } while (true);
2921 }
2922
2923 void PSParallelCompact::fill_blocks(size_t region_idx)
2924 {
2925 // Fill in the block table elements for the specified region. Each block
2926 // table element holds the number of live words in the region that are to the
2927 // left of the first object that starts in the block. Thus only blocks in
2928 // which an object starts need to be filled.
2929 //
2930 // The algorithm scans the section of the bitmap that corresponds to the
2931 // region, keeping a running total of the live words. When an object start is
2932 // found, if it's the first to start in the block that contains it, the
2933 // current total is written to the block table element.
2934 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
2935 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
2936 const size_t RegionSize = ParallelCompactData::RegionSize;
2937
2938 ParallelCompactData& sd = summary_data();
2939 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
2940 if (partial_obj_size >= RegionSize) {
2941 return; // No objects start in this region.
2942 }
2943
2944 // Ensure the first loop iteration decides that the block has changed.
2945 size_t cur_block = sd.block_count();
2946
2947 const ParMarkBitMap* const bitmap = mark_bitmap();
2948
2949 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
2950 assert((size_t)1 << Log2BitsPerBlock ==
2951 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
2952
2953 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
2954 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
2955 size_t live_bits = bitmap->words_to_bits(partial_obj_size);
2956 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
2957 while (beg_bit < range_end) {
2958 const size_t new_block = beg_bit >> Log2BitsPerBlock;
2959 if (new_block != cur_block) {
2960 cur_block = new_block;
2961 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
2962 }
2963
2964 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
2965 if (end_bit < range_end - 1) {
2966 live_bits += end_bit - beg_bit + 1;
2967 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
2968 } else {
2969 return;
2970 }
2971 }
2972 }
2973
2974 void
2975 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
2976 const MutableSpace* sp = space(space_id);
2977 if (sp->is_empty()) {
2978 return;
2979 }
2980
2981 ParallelCompactData& sd = PSParallelCompact::summary_data();
2982 ParMarkBitMap* const bitmap = mark_bitmap();
2983 HeapWord* const dp_addr = dense_prefix(space_id);
2984 HeapWord* beg_addr = sp->bottom();
2985 HeapWord* end_addr = sp->top();
2986
2987 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
2988
2989 const size_t beg_region = sd.addr_to_region_idx(beg_addr);
2990 const size_t dp_region = sd.addr_to_region_idx(dp_addr);
2991 if (beg_region < dp_region) {
2992 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
2993 }
2994
2995 // The destination of the first live object that starts in the region is one
2996 // past the end of the partial object entering the region (if any).
2997 HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
2998 HeapWord* const new_top = _space_info[space_id].new_top();
2999 assert(new_top >= dest_addr, "bad new_top value");
3000 const size_t words = pointer_delta(new_top, dest_addr);
3001
3002 if (words > 0) {
3003 ObjectStartArray* start_array = _space_info[space_id].start_array();
3004 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3005
3006 ParMarkBitMap::IterationStatus status;
3007 status = bitmap->iterate(&closure, dest_addr, end_addr);
3008 assert(status == ParMarkBitMap::full, "iteration not complete");
3009 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3010 "live objects skipped because closure is full");
3011 }
3012 }
3013
3014 jlong PSParallelCompact::millis_since_last_gc() {
3015 // We need a monotonically non-decreasing time in ms but
3016 // os::javaTimeMillis() does not guarantee monotonicity.
3017 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3018 jlong ret_val = now - _time_of_last_gc;
3019 // XXX See note in genCollectedHeap::millis_since_last_gc().
3020 if (ret_val < 0) {
3021 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);)
3022 return 0;
3023 }
3024 return ret_val;
3025 }
3026
3027 void PSParallelCompact::reset_millis_since_last_gc() {
3028 // We need a monotonically non-decreasing time in ms but
3029 // os::javaTimeMillis() does not guarantee monotonicity.
3030 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3031 }
3032
3033 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3034 {
3035 if (source() != destination()) {
3036 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3037 Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3038 }
3039 update_state(words_remaining());
3040 assert(is_full(), "sanity");
3041 return ParMarkBitMap::full;
3042 }
3043
3044 void MoveAndUpdateClosure::copy_partial_obj()
3045 {
3046 size_t words = words_remaining();
3047
3048 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3049 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3050 if (end_addr < range_end) {
3051 words = bitmap()->obj_size(source(), end_addr);
3052 }
3053
3054 // This test is necessary; if omitted, the pointer updates to a partial object
3055 // that crosses the dense prefix boundary could be overwritten.
3056 if (source() != destination()) {
3057 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3058 Copy::aligned_conjoint_words(source(), destination(), words);
3059 }
3060 update_state(words);
3061 }
3062
3063 void InstanceKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3064 PSParallelCompact::AdjustPointerClosure closure(cm);
3065 oop_oop_iterate_oop_maps<true>(obj, &closure);
3066 }
3067
3068 void InstanceMirrorKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3069 InstanceKlass::oop_pc_update_pointers(obj, cm);
3070
3071 PSParallelCompact::AdjustPointerClosure closure(cm);
3072 oop_oop_iterate_statics<true>(obj, &closure);
3073 }
3074
3075 void InstanceClassLoaderKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3076 InstanceKlass::oop_pc_update_pointers(obj, cm);
3077 }
3078
3079 #ifdef ASSERT
3080 template <class T> static void trace_reference_gc(const char *s, oop obj,
3081 T* referent_addr,
3082 T* next_addr,
3083 T* discovered_addr) {
3084 log_develop_trace(gc, ref)("%s obj " PTR_FORMAT, s, p2i(obj));
3085 log_develop_trace(gc, ref)(" referent_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3086 p2i(referent_addr), referent_addr ? p2i(oopDesc::load_decode_heap_oop(referent_addr)) : NULL);
3087 log_develop_trace(gc, ref)(" next_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3088 p2i(next_addr), next_addr ? p2i(oopDesc::load_decode_heap_oop(next_addr)) : NULL);
3089 log_develop_trace(gc, ref)(" discovered_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3090 p2i(discovered_addr), discovered_addr ? p2i(oopDesc::load_decode_heap_oop(discovered_addr)) : NULL);
3091 }
3092 #endif
3093
3094 template <class T>
3095 static void oop_pc_update_pointers_specialized(oop obj, ParCompactionManager* cm) {
3096 T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj);
3097 PSParallelCompact::adjust_pointer(referent_addr, cm);
3098 T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj);
3099 PSParallelCompact::adjust_pointer(next_addr, cm);
3100 T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj);
3101 PSParallelCompact::adjust_pointer(discovered_addr, cm);
3102 debug_only(trace_reference_gc("InstanceRefKlass::oop_update_ptrs", obj,
3103 referent_addr, next_addr, discovered_addr);)
3104 }
3105
3106 void InstanceRefKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3107 InstanceKlass::oop_pc_update_pointers(obj, cm);
3108
3109 if (UseCompressedOops) {
3110 oop_pc_update_pointers_specialized<narrowOop>(obj, cm);
3111 } else {
3112 oop_pc_update_pointers_specialized<oop>(obj, cm);
3113 }
3114 }
3115
3116 void ObjArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3117 assert(obj->is_objArray(), "obj must be obj array");
3118 PSParallelCompact::AdjustPointerClosure closure(cm);
3119 oop_oop_iterate_elements<true>(objArrayOop(obj), &closure);
3120 }
3121
3122 void TypeArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3123 assert(obj->is_typeArray(),"must be a type array");
3124 }
3125
3126 ParMarkBitMapClosure::IterationStatus
3127 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3128 assert(destination() != NULL, "sanity");
3129 assert(bitmap()->obj_size(addr) == words, "bad size");
3130
3131 _source = addr;
3132 assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) ==
3133 destination(), "wrong destination");
3134
3135 if (words > words_remaining()) {
3136 return ParMarkBitMap::would_overflow;
3137 }
3138
3139 // The start_array must be updated even if the object is not moving.
3140 if (_start_array != NULL) {
3141 _start_array->allocate_block(destination());
3142 }
3143
3144 if (destination() != source()) {
3145 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3146 Copy::aligned_conjoint_words(source(), destination(), words);
3147 }
3148
3149 oop moved_oop = (oop) destination();
3150 compaction_manager()->update_contents(moved_oop);
3151 assert(moved_oop->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop));
3152
3153 update_state(words);
3154 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3155 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3156 }
3157
3158 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3159 ParCompactionManager* cm,
3160 PSParallelCompact::SpaceId space_id) :
3161 ParMarkBitMapClosure(mbm, cm),
3162 _space_id(space_id),
3163 _start_array(PSParallelCompact::start_array(space_id))
3164 {
3165 }
3166
3167 // Updates the references in the object to their new values.
3168 ParMarkBitMapClosure::IterationStatus
3169 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3170 do_addr(addr);
3171 return ParMarkBitMap::incomplete;
3172 }
3173
3174 FillClosure::FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) :
3175 ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm),
3176 _start_array(PSParallelCompact::start_array(space_id))
3177 {
3178 assert(space_id == PSParallelCompact::old_space_id,
3179 "cannot use FillClosure in the young gen");
3180 }
3181
3182 ParMarkBitMapClosure::IterationStatus
3183 FillClosure::do_addr(HeapWord* addr, size_t size) {
3184 CollectedHeap::fill_with_objects(addr, size);
3185 HeapWord* const end = addr + size;
3186 do {
3187 _start_array->allocate_block(addr);
3188 addr += oop(addr)->size();
3189 } while (addr < end);
3190 return ParMarkBitMap::incomplete;
3191 }