1 /*
2 * Copyright (c) 2005, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/symbolTable.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "code/codeCache.hpp"
29 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp"
30 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.inline.hpp"
31 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
32 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
33 #include "gc_implementation/parallelScavenge/psCompactionManager.inline.hpp"
34 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp"
35 #include "gc_implementation/parallelScavenge/psMarkSweepDecorator.hpp"
36 #include "gc_implementation/parallelScavenge/psOldGen.hpp"
37 #include "gc_implementation/parallelScavenge/psParallelCompact.hpp"
38 #include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp"
39 #include "gc_implementation/parallelScavenge/psScavenge.hpp"
40 #include "gc_implementation/parallelScavenge/psYoungGen.hpp"
41 #include "gc_implementation/shared/gcHeapSummary.hpp"
42 #include "gc_implementation/shared/gcTimer.hpp"
43 #include "gc_implementation/shared/gcTrace.hpp"
44 #include "gc_implementation/shared/gcTraceTime.hpp"
45 #include "gc_implementation/shared/isGCActiveMark.hpp"
46 #include "gc_interface/gcCause.hpp"
47 #include "memory/gcLocker.inline.hpp"
48 #include "memory/referencePolicy.hpp"
49 #include "memory/referenceProcessor.hpp"
50 #include "oops/methodData.hpp"
51 #include "oops/oop.inline.hpp"
52 #include "oops/oop.pcgc.inline.hpp"
53 #include "runtime/fprofiler.hpp"
54 #include "runtime/safepoint.hpp"
55 #include "runtime/vmThread.hpp"
56 #include "services/management.hpp"
57 #include "services/memoryService.hpp"
58 #include "services/memTracker.hpp"
59 #include "utilities/events.hpp"
60 #include "utilities/stack.inline.hpp"
61
62 #include <math.h>
63
64 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
65
66 // All sizes are in HeapWords.
67 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words
68 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
69 const size_t ParallelCompactData::RegionSizeBytes =
70 RegionSize << LogHeapWordSize;
71 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
72 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
73 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
74
75 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words
76 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize;
77 const size_t ParallelCompactData::BlockSizeBytes =
78 BlockSize << LogHeapWordSize;
79 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1;
80 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1;
81 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask;
82
83 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
84 const size_t ParallelCompactData::Log2BlocksPerRegion =
85 Log2RegionSize - Log2BlockSize;
86
87 const ParallelCompactData::RegionData::region_sz_t
88 ParallelCompactData::RegionData::dc_shift = 27;
89
90 const ParallelCompactData::RegionData::region_sz_t
91 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
92
93 const ParallelCompactData::RegionData::region_sz_t
94 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
95
96 const ParallelCompactData::RegionData::region_sz_t
97 ParallelCompactData::RegionData::los_mask = ~dc_mask;
98
99 const ParallelCompactData::RegionData::region_sz_t
100 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
101
102 const ParallelCompactData::RegionData::region_sz_t
103 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
104
105 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
106 bool PSParallelCompact::_print_phases = false;
107
108 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
109 Klass* PSParallelCompact::_updated_int_array_klass_obj = NULL;
110
111 double PSParallelCompact::_dwl_mean;
112 double PSParallelCompact::_dwl_std_dev;
113 double PSParallelCompact::_dwl_first_term;
114 double PSParallelCompact::_dwl_adjustment;
115 #ifdef ASSERT
116 bool PSParallelCompact::_dwl_initialized = false;
117 #endif // #ifdef ASSERT
118
119 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
120 HeapWord* destination)
121 {
122 assert(src_region_idx != 0, "invalid src_region_idx");
123 assert(partial_obj_size != 0, "invalid partial_obj_size argument");
124 assert(destination != NULL, "invalid destination argument");
125
126 _src_region_idx = src_region_idx;
127 _partial_obj_size = partial_obj_size;
128 _destination = destination;
129
130 // These fields may not be updated below, so make sure they're clear.
131 assert(_dest_region_addr == NULL, "should have been cleared");
132 assert(_first_src_addr == NULL, "should have been cleared");
133
134 // Determine the number of destination regions for the partial object.
135 HeapWord* const last_word = destination + partial_obj_size - 1;
136 const ParallelCompactData& sd = PSParallelCompact::summary_data();
137 HeapWord* const beg_region_addr = sd.region_align_down(destination);
138 HeapWord* const end_region_addr = sd.region_align_down(last_word);
139
140 if (beg_region_addr == end_region_addr) {
141 // One destination region.
142 _destination_count = 1;
143 if (end_region_addr == destination) {
144 // The destination falls on a region boundary, thus the first word of the
145 // partial object will be the first word copied to the destination region.
146 _dest_region_addr = end_region_addr;
147 _first_src_addr = sd.region_to_addr(src_region_idx);
148 }
149 } else {
150 // Two destination regions. When copied, the partial object will cross a
151 // destination region boundary, so a word somewhere within the partial
152 // object will be the first word copied to the second destination region.
153 _destination_count = 2;
154 _dest_region_addr = end_region_addr;
155 const size_t ofs = pointer_delta(end_region_addr, destination);
156 assert(ofs < _partial_obj_size, "sanity");
157 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
158 }
159 }
160
161 void SplitInfo::clear()
162 {
163 _src_region_idx = 0;
164 _partial_obj_size = 0;
165 _destination = NULL;
166 _destination_count = 0;
167 _dest_region_addr = NULL;
168 _first_src_addr = NULL;
169 assert(!is_valid(), "sanity");
170 }
171
172 #ifdef ASSERT
173 void SplitInfo::verify_clear()
174 {
175 assert(_src_region_idx == 0, "not clear");
176 assert(_partial_obj_size == 0, "not clear");
177 assert(_destination == NULL, "not clear");
178 assert(_destination_count == 0, "not clear");
179 assert(_dest_region_addr == NULL, "not clear");
180 assert(_first_src_addr == NULL, "not clear");
181 }
182 #endif // #ifdef ASSERT
183
184
185 void PSParallelCompact::print_on_error(outputStream* st) {
186 _mark_bitmap.print_on_error(st);
187 }
188
189 #ifndef PRODUCT
190 const char* PSParallelCompact::space_names[] = {
191 "old ", "eden", "from", "to "
192 };
193
194 void PSParallelCompact::print_region_ranges()
195 {
196 tty->print_cr("space bottom top end new_top");
197 tty->print_cr("------ ---------- ---------- ---------- ----------");
198
199 for (unsigned int id = 0; id < last_space_id; ++id) {
200 const MutableSpace* space = _space_info[id].space();
201 tty->print_cr("%u %s "
202 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
203 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
204 id, space_names[id],
205 summary_data().addr_to_region_idx(space->bottom()),
206 summary_data().addr_to_region_idx(space->top()),
207 summary_data().addr_to_region_idx(space->end()),
208 summary_data().addr_to_region_idx(_space_info[id].new_top()));
209 }
210 }
211
212 void
213 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
214 {
215 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7)
216 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5)
217
218 ParallelCompactData& sd = PSParallelCompact::summary_data();
219 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
220 tty->print_cr(REGION_IDX_FORMAT " " PTR_FORMAT " "
221 REGION_IDX_FORMAT " " PTR_FORMAT " "
222 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
223 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
224 i, c->data_location(), dci, c->destination(),
225 c->partial_obj_size(), c->live_obj_size(),
226 c->data_size(), c->source_region(), c->destination_count());
227
228 #undef REGION_IDX_FORMAT
229 #undef REGION_DATA_FORMAT
230 }
231
232 void
233 print_generic_summary_data(ParallelCompactData& summary_data,
234 HeapWord* const beg_addr,
235 HeapWord* const end_addr)
236 {
237 size_t total_words = 0;
238 size_t i = summary_data.addr_to_region_idx(beg_addr);
239 const size_t last = summary_data.addr_to_region_idx(end_addr);
240 HeapWord* pdest = 0;
241
242 while (i <= last) {
243 ParallelCompactData::RegionData* c = summary_data.region(i);
244 if (c->data_size() != 0 || c->destination() != pdest) {
245 print_generic_summary_region(i, c);
246 total_words += c->data_size();
247 pdest = c->destination();
248 }
249 ++i;
250 }
251
252 tty->print_cr("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
253 }
254
255 void
256 print_generic_summary_data(ParallelCompactData& summary_data,
257 SpaceInfo* space_info)
258 {
259 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
260 const MutableSpace* space = space_info[id].space();
261 print_generic_summary_data(summary_data, space->bottom(),
262 MAX2(space->top(), space_info[id].new_top()));
263 }
264 }
265
266 void
267 print_initial_summary_region(size_t i,
268 const ParallelCompactData::RegionData* c,
269 bool newline = true)
270 {
271 tty->print(SIZE_FORMAT_W(5) " " PTR_FORMAT " "
272 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " "
273 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
274 i, c->destination(),
275 c->partial_obj_size(), c->live_obj_size(),
276 c->data_size(), c->source_region(), c->destination_count());
277 if (newline) tty->cr();
278 }
279
280 void
281 print_initial_summary_data(ParallelCompactData& summary_data,
282 const MutableSpace* space) {
283 if (space->top() == space->bottom()) {
284 return;
285 }
286
287 const size_t region_size = ParallelCompactData::RegionSize;
288 typedef ParallelCompactData::RegionData RegionData;
289 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
290 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
291 const RegionData* c = summary_data.region(end_region - 1);
292 HeapWord* end_addr = c->destination() + c->data_size();
293 const size_t live_in_space = pointer_delta(end_addr, space->bottom());
294
295 // Print (and count) the full regions at the beginning of the space.
296 size_t full_region_count = 0;
297 size_t i = summary_data.addr_to_region_idx(space->bottom());
298 while (i < end_region && summary_data.region(i)->data_size() == region_size) {
299 print_initial_summary_region(i, summary_data.region(i));
300 ++full_region_count;
301 ++i;
302 }
303
304 size_t live_to_right = live_in_space - full_region_count * region_size;
305
306 double max_reclaimed_ratio = 0.0;
307 size_t max_reclaimed_ratio_region = 0;
308 size_t max_dead_to_right = 0;
309 size_t max_live_to_right = 0;
310
311 // Print the 'reclaimed ratio' for regions while there is something live in
312 // the region or to the right of it. The remaining regions are empty (and
313 // uninteresting), and computing the ratio will result in division by 0.
314 while (i < end_region && live_to_right > 0) {
315 c = summary_data.region(i);
316 HeapWord* const region_addr = summary_data.region_to_addr(i);
317 const size_t used_to_right = pointer_delta(space->top(), region_addr);
318 const size_t dead_to_right = used_to_right - live_to_right;
319 const double reclaimed_ratio = double(dead_to_right) / live_to_right;
320
321 if (reclaimed_ratio > max_reclaimed_ratio) {
322 max_reclaimed_ratio = reclaimed_ratio;
323 max_reclaimed_ratio_region = i;
324 max_dead_to_right = dead_to_right;
325 max_live_to_right = live_to_right;
326 }
327
328 print_initial_summary_region(i, c, false);
329 tty->print_cr(" %12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
330 reclaimed_ratio, dead_to_right, live_to_right);
331
332 live_to_right -= c->data_size();
333 ++i;
334 }
335
336 // Any remaining regions are empty. Print one more if there is one.
337 if (i < end_region) {
338 print_initial_summary_region(i, summary_data.region(i));
339 }
340
341 tty->print_cr("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " "
342 "l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
343 max_reclaimed_ratio_region, max_dead_to_right,
344 max_live_to_right, max_reclaimed_ratio);
345 }
346
347 void
348 print_initial_summary_data(ParallelCompactData& summary_data,
349 SpaceInfo* space_info) {
350 unsigned int id = PSParallelCompact::old_space_id;
351 const MutableSpace* space;
352 do {
353 space = space_info[id].space();
354 print_initial_summary_data(summary_data, space);
355 } while (++id < PSParallelCompact::eden_space_id);
356
357 do {
358 space = space_info[id].space();
359 print_generic_summary_data(summary_data, space->bottom(), space->top());
360 } while (++id < PSParallelCompact::last_space_id);
361 }
362 #endif // #ifndef PRODUCT
363
364 #ifdef ASSERT
365 size_t add_obj_count;
366 size_t add_obj_size;
367 size_t mark_bitmap_count;
368 size_t mark_bitmap_size;
369 #endif // #ifdef ASSERT
370
371 ParallelCompactData::ParallelCompactData()
372 {
373 _region_start = 0;
374
375 _region_vspace = 0;
376 _reserved_byte_size = 0;
377 _region_data = 0;
378 _region_count = 0;
379
380 _block_vspace = 0;
381 _block_data = 0;
382 _block_count = 0;
383 }
384
385 bool ParallelCompactData::initialize(MemRegion covered_region)
386 {
387 _region_start = covered_region.start();
388 const size_t region_size = covered_region.word_size();
389 DEBUG_ONLY(_region_end = _region_start + region_size;)
390
391 assert(region_align_down(_region_start) == _region_start,
392 "region start not aligned");
393 assert((region_size & RegionSizeOffsetMask) == 0,
394 "region size not a multiple of RegionSize");
395
396 bool result = initialize_region_data(region_size) && initialize_block_data();
397 return result;
398 }
399
400 PSVirtualSpace*
401 ParallelCompactData::create_vspace(size_t count, size_t element_size)
402 {
403 const size_t raw_bytes = count * element_size;
404 const size_t page_sz = os::page_size_for_region(raw_bytes, 10);
405 const size_t granularity = os::vm_allocation_granularity();
406 _reserved_byte_size = align_size_up(raw_bytes, MAX2(page_sz, granularity));
407
408 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
409 MAX2(page_sz, granularity);
410 ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0);
411 os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(),
412 rs.size());
413
414 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
415
416 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
417 if (vspace != 0) {
418 if (vspace->expand_by(_reserved_byte_size)) {
419 return vspace;
420 }
421 delete vspace;
422 // Release memory reserved in the space.
423 rs.release();
424 }
425
426 return 0;
427 }
428
429 bool ParallelCompactData::initialize_region_data(size_t region_size)
430 {
431 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
432 _region_vspace = create_vspace(count, sizeof(RegionData));
433 if (_region_vspace != 0) {
434 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
435 _region_count = count;
436 return true;
437 }
438 return false;
439 }
440
441 bool ParallelCompactData::initialize_block_data()
442 {
443 assert(_region_count != 0, "region data must be initialized first");
444 const size_t count = _region_count << Log2BlocksPerRegion;
445 _block_vspace = create_vspace(count, sizeof(BlockData));
446 if (_block_vspace != 0) {
447 _block_data = (BlockData*)_block_vspace->reserved_low_addr();
448 _block_count = count;
449 return true;
450 }
451 return false;
452 }
453
454 void ParallelCompactData::clear()
455 {
456 memset(_region_data, 0, _region_vspace->committed_size());
457 memset(_block_data, 0, _block_vspace->committed_size());
458 }
459
460 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
461 assert(beg_region <= _region_count, "beg_region out of range");
462 assert(end_region <= _region_count, "end_region out of range");
463 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize");
464
465 const size_t region_cnt = end_region - beg_region;
466 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
467
468 const size_t beg_block = beg_region * BlocksPerRegion;
469 const size_t block_cnt = region_cnt * BlocksPerRegion;
470 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));
471 }
472
473 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
474 {
475 const RegionData* cur_cp = region(region_idx);
476 const RegionData* const end_cp = region(region_count() - 1);
477
478 HeapWord* result = region_to_addr(region_idx);
479 if (cur_cp < end_cp) {
480 do {
481 result += cur_cp->partial_obj_size();
482 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
483 }
484 return result;
485 }
486
487 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
488 {
489 const size_t obj_ofs = pointer_delta(addr, _region_start);
490 const size_t beg_region = obj_ofs >> Log2RegionSize;
491 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
492
493 DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
494 DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
495
496 if (beg_region == end_region) {
497 // All in one region.
498 _region_data[beg_region].add_live_obj(len);
499 return;
500 }
501
502 // First region.
503 const size_t beg_ofs = region_offset(addr);
504 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
505
506 Klass* klass = ((oop)addr)->klass();
507 // Middle regions--completely spanned by this object.
508 for (size_t region = beg_region + 1; region < end_region; ++region) {
509 _region_data[region].set_partial_obj_size(RegionSize);
510 _region_data[region].set_partial_obj_addr(addr);
511 }
512
513 // Last region.
514 const size_t end_ofs = region_offset(addr + len - 1);
515 _region_data[end_region].set_partial_obj_size(end_ofs + 1);
516 _region_data[end_region].set_partial_obj_addr(addr);
517 }
518
519 void
520 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
521 {
522 assert(region_offset(beg) == 0, "not RegionSize aligned");
523 assert(region_offset(end) == 0, "not RegionSize aligned");
524
525 size_t cur_region = addr_to_region_idx(beg);
526 const size_t end_region = addr_to_region_idx(end);
527 HeapWord* addr = beg;
528 while (cur_region < end_region) {
529 _region_data[cur_region].set_destination(addr);
530 _region_data[cur_region].set_destination_count(0);
531 _region_data[cur_region].set_source_region(cur_region);
532 _region_data[cur_region].set_data_location(addr);
533
534 // Update live_obj_size so the region appears completely full.
535 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
536 _region_data[cur_region].set_live_obj_size(live_size);
537
538 ++cur_region;
539 addr += RegionSize;
540 }
541 }
542
543 // Find the point at which a space can be split and, if necessary, record the
544 // split point.
545 //
546 // If the current src region (which overflowed the destination space) doesn't
547 // have a partial object, the split point is at the beginning of the current src
548 // region (an "easy" split, no extra bookkeeping required).
549 //
550 // If the current src region has a partial object, the split point is in the
551 // region where that partial object starts (call it the split_region). If
552 // split_region has a partial object, then the split point is just after that
553 // partial object (a "hard" split where we have to record the split data and
554 // zero the partial_obj_size field). With a "hard" split, we know that the
555 // partial_obj ends within split_region because the partial object that caused
556 // the overflow starts in split_region. If split_region doesn't have a partial
557 // obj, then the split is at the beginning of split_region (another "easy"
558 // split).
559 HeapWord*
560 ParallelCompactData::summarize_split_space(size_t src_region,
561 SplitInfo& split_info,
562 HeapWord* destination,
563 HeapWord* target_end,
564 HeapWord** target_next)
565 {
566 assert(destination <= target_end, "sanity");
567 assert(destination + _region_data[src_region].data_size() > target_end,
568 "region should not fit into target space");
569 assert(is_region_aligned(target_end), "sanity");
570
571 size_t split_region = src_region;
572 HeapWord* split_destination = destination;
573 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
574
575 if (destination + partial_obj_size > target_end) {
576 // The split point is just after the partial object (if any) in the
577 // src_region that contains the start of the object that overflowed the
578 // destination space.
579 //
580 // Find the start of the "overflow" object and set split_region to the
581 // region containing it.
582 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
583 split_region = addr_to_region_idx(overflow_obj);
584
585 // Clear the source_region field of all destination regions whose first word
586 // came from data after the split point (a non-null source_region field
587 // implies a region must be filled).
588 //
589 // An alternative to the simple loop below: clear during post_compact(),
590 // which uses memcpy instead of individual stores, and is easy to
591 // parallelize. (The downside is that it clears the entire RegionData
592 // object as opposed to just one field.)
593 //
594 // post_compact() would have to clear the summary data up to the highest
595 // address that was written during the summary phase, which would be
596 //
597 // max(top, max(new_top, clear_top))
598 //
599 // where clear_top is a new field in SpaceInfo. Would have to set clear_top
600 // to target_end.
601 const RegionData* const sr = region(split_region);
602 const size_t beg_idx =
603 addr_to_region_idx(region_align_up(sr->destination() +
604 sr->partial_obj_size()));
605 const size_t end_idx = addr_to_region_idx(target_end);
606
607 if (TraceParallelOldGCSummaryPhase) {
608 gclog_or_tty->print_cr("split: clearing source_region field in ["
609 SIZE_FORMAT ", " SIZE_FORMAT ")",
610 beg_idx, end_idx);
611 }
612 for (size_t idx = beg_idx; idx < end_idx; ++idx) {
613 _region_data[idx].set_source_region(0);
614 }
615
616 // Set split_destination and partial_obj_size to reflect the split region.
617 split_destination = sr->destination();
618 partial_obj_size = sr->partial_obj_size();
619 }
620
621 // The split is recorded only if a partial object extends onto the region.
622 if (partial_obj_size != 0) {
623 _region_data[split_region].set_partial_obj_size(0);
624 split_info.record(split_region, partial_obj_size, split_destination);
625 }
626
627 // Setup the continuation addresses.
628 *target_next = split_destination + partial_obj_size;
629 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
630
631 if (TraceParallelOldGCSummaryPhase) {
632 const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
633 gclog_or_tty->print_cr("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT
634 " pos=" SIZE_FORMAT,
635 split_type, source_next, split_region,
636 partial_obj_size);
637 gclog_or_tty->print_cr("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT
638 " tn=" PTR_FORMAT,
639 split_type, split_destination,
640 addr_to_region_idx(split_destination),
641 *target_next);
642
643 if (partial_obj_size != 0) {
644 HeapWord* const po_beg = split_info.destination();
645 HeapWord* const po_end = po_beg + split_info.partial_obj_size();
646 gclog_or_tty->print_cr("%s split: "
647 "po_beg=" PTR_FORMAT " " SIZE_FORMAT " "
648 "po_end=" PTR_FORMAT " " SIZE_FORMAT,
649 split_type,
650 po_beg, addr_to_region_idx(po_beg),
651 po_end, addr_to_region_idx(po_end));
652 }
653 }
654
655 return source_next;
656 }
657
658 bool ParallelCompactData::summarize(SplitInfo& split_info,
659 HeapWord* source_beg, HeapWord* source_end,
660 HeapWord** source_next,
661 HeapWord* target_beg, HeapWord* target_end,
662 HeapWord** target_next)
663 {
664 if (TraceParallelOldGCSummaryPhase) {
665 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
666 tty->print_cr("sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
667 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
668 source_beg, source_end, source_next_val,
669 target_beg, target_end, *target_next);
670 }
671
672 size_t cur_region = addr_to_region_idx(source_beg);
673 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
674
675 HeapWord *dest_addr = target_beg;
676 while (cur_region < end_region) {
677 // The destination must be set even if the region has no data.
678 _region_data[cur_region].set_destination(dest_addr);
679
680 size_t words = _region_data[cur_region].data_size();
681 if (words > 0) {
682 // If cur_region does not fit entirely into the target space, find a point
683 // at which the source space can be 'split' so that part is copied to the
684 // target space and the rest is copied elsewhere.
685 if (dest_addr + words > target_end) {
686 assert(source_next != NULL, "source_next is NULL when splitting");
687 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
688 target_end, target_next);
689 return false;
690 }
691
692 // Compute the destination_count for cur_region, and if necessary, update
693 // source_region for a destination region. The source_region field is
694 // updated if cur_region is the first (left-most) region to be copied to a
695 // destination region.
696 //
697 // The destination_count calculation is a bit subtle. A region that has
698 // data that compacts into itself does not count itself as a destination.
699 // This maintains the invariant that a zero count means the region is
700 // available and can be claimed and then filled.
701 uint destination_count = 0;
702 if (split_info.is_split(cur_region)) {
703 // The current region has been split: the partial object will be copied
704 // to one destination space and the remaining data will be copied to
705 // another destination space. Adjust the initial destination_count and,
706 // if necessary, set the source_region field if the partial object will
707 // cross a destination region boundary.
708 destination_count = split_info.destination_count();
709 if (destination_count == 2) {
710 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
711 _region_data[dest_idx].set_source_region(cur_region);
712 }
713 }
714
715 HeapWord* const last_addr = dest_addr + words - 1;
716 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
717 const size_t dest_region_2 = addr_to_region_idx(last_addr);
718
719 // Initially assume that the destination regions will be the same and
720 // adjust the value below if necessary. Under this assumption, if
721 // cur_region == dest_region_2, then cur_region will be compacted
722 // completely into itself.
723 destination_count += cur_region == dest_region_2 ? 0 : 1;
724 if (dest_region_1 != dest_region_2) {
725 // Destination regions differ; adjust destination_count.
726 destination_count += 1;
727 // Data from cur_region will be copied to the start of dest_region_2.
728 _region_data[dest_region_2].set_source_region(cur_region);
729 } else if (region_offset(dest_addr) == 0) {
730 // Data from cur_region will be copied to the start of the destination
731 // region.
732 _region_data[dest_region_1].set_source_region(cur_region);
733 }
734
735 _region_data[cur_region].set_destination_count(destination_count);
736 _region_data[cur_region].set_data_location(region_to_addr(cur_region));
737 dest_addr += words;
738 }
739
740 ++cur_region;
741 }
742
743 *target_next = dest_addr;
744 return true;
745 }
746
747 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) {
748 assert(addr != NULL, "Should detect NULL oop earlier");
749 assert(PSParallelCompact::gc_heap()->is_in(addr), "not in heap");
750 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked");
751
752 // Region covering the object.
753 RegionData* const region_ptr = addr_to_region_ptr(addr);
754 HeapWord* result = region_ptr->destination();
755
756 // If the entire Region is live, the new location is region->destination + the
757 // offset of the object within in the Region.
758
759 // Run some performance tests to determine if this special case pays off. It
760 // is worth it for pointers into the dense prefix. If the optimization to
761 // avoid pointer updates in regions that only point to the dense prefix is
762 // ever implemented, this should be revisited.
763 if (region_ptr->data_size() == RegionSize) {
764 result += region_offset(addr);
765 return result;
766 }
767
768 // Otherwise, the new location is region->destination + block offset + the
769 // number of live words in the Block that are (a) to the left of addr and (b)
770 // due to objects that start in the Block.
771
772 // Fill in the block table if necessary. This is unsynchronized, so multiple
773 // threads may fill the block table for a region (harmless, since it is
774 // idempotent).
775 if (!region_ptr->blocks_filled()) {
776 PSParallelCompact::fill_blocks(addr_to_region_idx(addr));
777 region_ptr->set_blocks_filled();
778 }
779
780 HeapWord* const search_start = block_align_down(addr);
781 const size_t block_offset = addr_to_block_ptr(addr)->offset();
782
783 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
784 const size_t live = bitmap->live_words_in_range(search_start, oop(addr));
785 result += block_offset + live;
786 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result));
787 return result;
788 }
789
790 #ifdef ASSERT
791 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
792 {
793 const size_t* const beg = (const size_t*)vspace->committed_low_addr();
794 const size_t* const end = (const size_t*)vspace->committed_high_addr();
795 for (const size_t* p = beg; p < end; ++p) {
796 assert(*p == 0, "not zero");
797 }
798 }
799
800 void ParallelCompactData::verify_clear()
801 {
802 verify_clear(_region_vspace);
803 verify_clear(_block_vspace);
804 }
805 #endif // #ifdef ASSERT
806
807 STWGCTimer PSParallelCompact::_gc_timer;
808 ParallelOldTracer PSParallelCompact::_gc_tracer;
809 elapsedTimer PSParallelCompact::_accumulated_time;
810 unsigned int PSParallelCompact::_total_invocations = 0;
811 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
812 jlong PSParallelCompact::_time_of_last_gc = 0;
813 CollectorCounters* PSParallelCompact::_counters = NULL;
814 ParMarkBitMap PSParallelCompact::_mark_bitmap;
815 ParallelCompactData PSParallelCompact::_summary_data;
816
817 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
818
819 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
820
821 void PSParallelCompact::KeepAliveClosure::do_oop(oop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
822 void PSParallelCompact::KeepAliveClosure::do_oop(narrowOop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
823
824 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_pointer_closure;
825 PSParallelCompact::AdjustKlassClosure PSParallelCompact::_adjust_klass_closure;
826
827 void PSParallelCompact::AdjustPointerClosure::do_oop(oop* p) { adjust_pointer(p); }
828 void PSParallelCompact::AdjustPointerClosure::do_oop(narrowOop* p) { adjust_pointer(p); }
829
830 void PSParallelCompact::FollowStackClosure::do_void() { _compaction_manager->follow_marking_stacks(); }
831
832 void PSParallelCompact::MarkAndPushClosure::do_oop(oop* p) {
833 mark_and_push(_compaction_manager, p);
834 }
835 void PSParallelCompact::MarkAndPushClosure::do_oop(narrowOop* p) { mark_and_push(_compaction_manager, p); }
836
837 void PSParallelCompact::FollowKlassClosure::do_klass(Klass* klass) {
838 klass->oops_do(_mark_and_push_closure);
839 }
840 void PSParallelCompact::AdjustKlassClosure::do_klass(Klass* klass) {
841 klass->oops_do(&PSParallelCompact::_adjust_pointer_closure);
842 }
843
844 void PSParallelCompact::post_initialize() {
845 ParallelScavengeHeap* heap = gc_heap();
846 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
847
848 MemRegion mr = heap->reserved_region();
849 _ref_processor =
850 new ReferenceProcessor(mr, // span
851 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
852 (int) ParallelGCThreads, // mt processing degree
853 true, // mt discovery
854 (int) ParallelGCThreads, // mt discovery degree
855 true, // atomic_discovery
856 &_is_alive_closure); // non-header is alive closure
857 _counters = new CollectorCounters("PSParallelCompact", 1);
858
859 // Initialize static fields in ParCompactionManager.
860 ParCompactionManager::initialize(mark_bitmap());
861 }
862
863 bool PSParallelCompact::initialize() {
864 ParallelScavengeHeap* heap = gc_heap();
865 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
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 = gc_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 // Simple class for storing info about the heap at the start of GC, to be used
921 // after GC for comparison/printing.
922 class PreGCValues {
923 public:
924 PreGCValues() { }
925 PreGCValues(ParallelScavengeHeap* heap) { fill(heap); }
926
927 void fill(ParallelScavengeHeap* heap) {
928 _heap_used = heap->used();
929 _young_gen_used = heap->young_gen()->used_in_bytes();
930 _old_gen_used = heap->old_gen()->used_in_bytes();
931 _metadata_used = MetaspaceAux::used_bytes();
932 };
933
934 size_t heap_used() const { return _heap_used; }
935 size_t young_gen_used() const { return _young_gen_used; }
936 size_t old_gen_used() const { return _old_gen_used; }
937 size_t metadata_used() const { return _metadata_used; }
938
939 private:
940 size_t _heap_used;
941 size_t _young_gen_used;
942 size_t _old_gen_used;
943 size_t _metadata_used;
944 };
945
946 void
947 PSParallelCompact::clear_data_covering_space(SpaceId id)
948 {
949 // At this point, top is the value before GC, new_top() is the value that will
950 // be set at the end of GC. The marking bitmap is cleared to top; nothing
951 // should be marked above top. The summary data is cleared to the larger of
952 // top & new_top.
953 MutableSpace* const space = _space_info[id].space();
954 HeapWord* const bot = space->bottom();
955 HeapWord* const top = space->top();
956 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
957
958 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
959 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
960 _mark_bitmap.clear_range(beg_bit, end_bit);
961
962 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
963 const size_t end_region =
964 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
965 _summary_data.clear_range(beg_region, end_region);
966
967 // Clear the data used to 'split' regions.
968 SplitInfo& split_info = _space_info[id].split_info();
969 if (split_info.is_valid()) {
970 split_info.clear();
971 }
972 DEBUG_ONLY(split_info.verify_clear();)
973 }
974
975 void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values)
976 {
977 // Update the from & to space pointers in space_info, since they are swapped
978 // at each young gen gc. Do the update unconditionally (even though a
979 // promotion failure does not swap spaces) because an unknown number of minor
980 // collections will have swapped the spaces an unknown number of times.
981 GCTraceTime tm("pre compact", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
982 ParallelScavengeHeap* heap = gc_heap();
983 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
984 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
985
986 pre_gc_values->fill(heap);
987
988 DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
989 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
990
991 // Increment the invocation count
992 heap->increment_total_collections(true);
993
994 // We need to track unique mark sweep invocations as well.
995 _total_invocations++;
996
997 heap->print_heap_before_gc();
998 heap->trace_heap_before_gc(&_gc_tracer);
999
1000 // Fill in TLABs
1001 heap->accumulate_statistics_all_tlabs();
1002 heap->ensure_parsability(true); // retire TLABs
1003
1004 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
1005 HandleMark hm; // Discard invalid handles created during verification
1006 Universe::verify(" VerifyBeforeGC:");
1007 }
1008
1009 // Verify object start arrays
1010 if (VerifyObjectStartArray &&
1011 VerifyBeforeGC) {
1012 heap->old_gen()->verify_object_start_array();
1013 }
1014
1015 DEBUG_ONLY(mark_bitmap()->verify_clear();)
1016 DEBUG_ONLY(summary_data().verify_clear();)
1017
1018 // Have worker threads release resources the next time they run a task.
1019 gc_task_manager()->release_all_resources();
1020 }
1021
1022 void PSParallelCompact::post_compact()
1023 {
1024 GCTraceTime tm("post compact", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
1025
1026 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1027 // Clear the marking bitmap, summary data and split info.
1028 clear_data_covering_space(SpaceId(id));
1029 // Update top(). Must be done after clearing the bitmap and summary data.
1030 _space_info[id].publish_new_top();
1031 }
1032
1033 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1034 MutableSpace* const from_space = _space_info[from_space_id].space();
1035 MutableSpace* const to_space = _space_info[to_space_id].space();
1036
1037 ParallelScavengeHeap* heap = gc_heap();
1038 bool eden_empty = eden_space->is_empty();
1039 if (!eden_empty) {
1040 eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1041 heap->young_gen(), heap->old_gen());
1042 }
1043
1044 // Update heap occupancy information which is used as input to the soft ref
1045 // clearing policy at the next gc.
1046 Universe::update_heap_info_at_gc();
1047
1048 bool young_gen_empty = eden_empty && from_space->is_empty() &&
1049 to_space->is_empty();
1050
1051 BarrierSet* bs = heap->barrier_set();
1052 if (bs->is_a(BarrierSet::ModRef)) {
1053 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
1054 MemRegion old_mr = heap->old_gen()->reserved();
1055
1056 if (young_gen_empty) {
1057 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
1058 } else {
1059 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1060 }
1061 }
1062
1063 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1064 ClassLoaderDataGraph::purge();
1065 MetaspaceAux::verify_metrics();
1066
1067 Threads::gc_epilogue();
1068 CodeCache::gc_epilogue();
1069 JvmtiExport::gc_epilogue();
1070
1071 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1072
1073 ref_processor()->enqueue_discovered_references(NULL);
1074
1075 if (ZapUnusedHeapArea) {
1076 heap->gen_mangle_unused_area();
1077 }
1078
1079 // Update time of last GC
1080 reset_millis_since_last_gc();
1081 }
1082
1083 HeapWord*
1084 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1085 bool maximum_compaction)
1086 {
1087 const size_t region_size = ParallelCompactData::RegionSize;
1088 const ParallelCompactData& sd = summary_data();
1089
1090 const MutableSpace* const space = _space_info[id].space();
1091 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1092 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1093 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1094
1095 // Skip full regions at the beginning of the space--they are necessarily part
1096 // of the dense prefix.
1097 size_t full_count = 0;
1098 const RegionData* cp;
1099 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1100 ++full_count;
1101 }
1102
1103 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1104 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1105 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1106 if (maximum_compaction || cp == end_cp || interval_ended) {
1107 _maximum_compaction_gc_num = total_invocations();
1108 return sd.region_to_addr(cp);
1109 }
1110
1111 HeapWord* const new_top = _space_info[id].new_top();
1112 const size_t space_live = pointer_delta(new_top, space->bottom());
1113 const size_t space_used = space->used_in_words();
1114 const size_t space_capacity = space->capacity_in_words();
1115
1116 const double cur_density = double(space_live) / space_capacity;
1117 const double deadwood_density =
1118 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1119 const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1120
1121 if (TraceParallelOldGCDensePrefix) {
1122 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1123 cur_density, deadwood_density, deadwood_goal);
1124 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1125 "space_cap=" SIZE_FORMAT,
1126 space_live, space_used,
1127 space_capacity);
1128 }
1129
1130 // XXX - Use binary search?
1131 HeapWord* dense_prefix = sd.region_to_addr(cp);
1132 const RegionData* full_cp = cp;
1133 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1134 while (cp < end_cp) {
1135 HeapWord* region_destination = cp->destination();
1136 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1137 if (TraceParallelOldGCDensePrefix && Verbose) {
1138 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1139 "dp=" SIZE_FORMAT_W(8) " " "cdw=" SIZE_FORMAT_W(8),
1140 sd.region(cp), region_destination,
1141 dense_prefix, cur_deadwood);
1142 }
1143
1144 if (cur_deadwood >= deadwood_goal) {
1145 // Found the region that has the correct amount of deadwood to the left.
1146 // This typically occurs after crossing a fairly sparse set of regions, so
1147 // iterate backwards over those sparse regions, looking for the region
1148 // that has the lowest density of live objects 'to the right.'
1149 size_t space_to_left = sd.region(cp) * region_size;
1150 size_t live_to_left = space_to_left - cur_deadwood;
1151 size_t space_to_right = space_capacity - space_to_left;
1152 size_t live_to_right = space_live - live_to_left;
1153 double density_to_right = double(live_to_right) / space_to_right;
1154 while (cp > full_cp) {
1155 --cp;
1156 const size_t prev_region_live_to_right = live_to_right -
1157 cp->data_size();
1158 const size_t prev_region_space_to_right = space_to_right + region_size;
1159 double prev_region_density_to_right =
1160 double(prev_region_live_to_right) / prev_region_space_to_right;
1161 if (density_to_right <= prev_region_density_to_right) {
1162 return dense_prefix;
1163 }
1164 if (TraceParallelOldGCDensePrefix && Verbose) {
1165 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1166 "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1167 prev_region_density_to_right);
1168 }
1169 dense_prefix -= region_size;
1170 live_to_right = prev_region_live_to_right;
1171 space_to_right = prev_region_space_to_right;
1172 density_to_right = prev_region_density_to_right;
1173 }
1174 return dense_prefix;
1175 }
1176
1177 dense_prefix += region_size;
1178 ++cp;
1179 }
1180
1181 return dense_prefix;
1182 }
1183
1184 #ifndef PRODUCT
1185 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1186 const SpaceId id,
1187 const bool maximum_compaction,
1188 HeapWord* const addr)
1189 {
1190 const size_t region_idx = summary_data().addr_to_region_idx(addr);
1191 RegionData* const cp = summary_data().region(region_idx);
1192 const MutableSpace* const space = _space_info[id].space();
1193 HeapWord* const new_top = _space_info[id].new_top();
1194
1195 const size_t space_live = pointer_delta(new_top, space->bottom());
1196 const size_t dead_to_left = pointer_delta(addr, cp->destination());
1197 const size_t space_cap = space->capacity_in_words();
1198 const double dead_to_left_pct = double(dead_to_left) / space_cap;
1199 const size_t live_to_right = new_top - cp->destination();
1200 const size_t dead_to_right = space->top() - addr - live_to_right;
1201
1202 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1203 "spl=" SIZE_FORMAT " "
1204 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1205 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1206 " ratio=%10.8f",
1207 algorithm, addr, region_idx,
1208 space_live,
1209 dead_to_left, dead_to_left_pct,
1210 dead_to_right, live_to_right,
1211 double(dead_to_right) / live_to_right);
1212 }
1213 #endif // #ifndef PRODUCT
1214
1215 // Return a fraction indicating how much of the generation can be treated as
1216 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution
1217 // based on the density of live objects in the generation to determine a limit,
1218 // which is then adjusted so the return value is min_percent when the density is
1219 // 1.
1220 //
1221 // The following table shows some return values for a different values of the
1222 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1223 // min_percent is 1.
1224 //
1225 // fraction allowed as dead wood
1226 // -----------------------------------------------------------------
1227 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1228 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1229 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1230 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1231 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1232 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1233 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1234 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1235 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1236 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1237 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1238 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1239 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1240 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1241 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1242 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1243 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1244 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1245 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1246 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1247 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1248 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1249 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1250
1251 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1252 {
1253 assert(_dwl_initialized, "uninitialized");
1254
1255 // The raw limit is the value of the normal distribution at x = density.
1256 const double raw_limit = normal_distribution(density);
1257
1258 // Adjust the raw limit so it becomes the minimum when the density is 1.
1259 //
1260 // First subtract the adjustment value (which is simply the precomputed value
1261 // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1262 // Then add the minimum value, so the minimum is returned when the density is
1263 // 1. Finally, prevent negative values, which occur when the mean is not 0.5.
1264 const double min = double(min_percent) / 100.0;
1265 const double limit = raw_limit - _dwl_adjustment + min;
1266 return MAX2(limit, 0.0);
1267 }
1268
1269 ParallelCompactData::RegionData*
1270 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1271 const RegionData* end)
1272 {
1273 const size_t region_size = ParallelCompactData::RegionSize;
1274 ParallelCompactData& sd = summary_data();
1275 size_t left = sd.region(beg);
1276 size_t right = end > beg ? sd.region(end) - 1 : left;
1277
1278 // Binary search.
1279 while (left < right) {
1280 // Equivalent to (left + right) / 2, but does not overflow.
1281 const size_t middle = left + (right - left) / 2;
1282 RegionData* const middle_ptr = sd.region(middle);
1283 HeapWord* const dest = middle_ptr->destination();
1284 HeapWord* const addr = sd.region_to_addr(middle);
1285 assert(dest != NULL, "sanity");
1286 assert(dest <= addr, "must move left");
1287
1288 if (middle > left && dest < addr) {
1289 right = middle - 1;
1290 } else if (middle < right && middle_ptr->data_size() == region_size) {
1291 left = middle + 1;
1292 } else {
1293 return middle_ptr;
1294 }
1295 }
1296 return sd.region(left);
1297 }
1298
1299 ParallelCompactData::RegionData*
1300 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1301 const RegionData* end,
1302 size_t dead_words)
1303 {
1304 ParallelCompactData& sd = summary_data();
1305 size_t left = sd.region(beg);
1306 size_t right = end > beg ? sd.region(end) - 1 : left;
1307
1308 // Binary search.
1309 while (left < right) {
1310 // Equivalent to (left + right) / 2, but does not overflow.
1311 const size_t middle = left + (right - left) / 2;
1312 RegionData* const middle_ptr = sd.region(middle);
1313 HeapWord* const dest = middle_ptr->destination();
1314 HeapWord* const addr = sd.region_to_addr(middle);
1315 assert(dest != NULL, "sanity");
1316 assert(dest <= addr, "must move left");
1317
1318 const size_t dead_to_left = pointer_delta(addr, dest);
1319 if (middle > left && dead_to_left > dead_words) {
1320 right = middle - 1;
1321 } else if (middle < right && dead_to_left < dead_words) {
1322 left = middle + 1;
1323 } else {
1324 return middle_ptr;
1325 }
1326 }
1327 return sd.region(left);
1328 }
1329
1330 // The result is valid during the summary phase, after the initial summarization
1331 // of each space into itself, and before final summarization.
1332 inline double
1333 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1334 HeapWord* const bottom,
1335 HeapWord* const top,
1336 HeapWord* const new_top)
1337 {
1338 ParallelCompactData& sd = summary_data();
1339
1340 assert(cp != NULL, "sanity");
1341 assert(bottom != NULL, "sanity");
1342 assert(top != NULL, "sanity");
1343 assert(new_top != NULL, "sanity");
1344 assert(top >= new_top, "summary data problem?");
1345 assert(new_top > bottom, "space is empty; should not be here");
1346 assert(new_top >= cp->destination(), "sanity");
1347 assert(top >= sd.region_to_addr(cp), "sanity");
1348
1349 HeapWord* const destination = cp->destination();
1350 const size_t dense_prefix_live = pointer_delta(destination, bottom);
1351 const size_t compacted_region_live = pointer_delta(new_top, destination);
1352 const size_t compacted_region_used = pointer_delta(top,
1353 sd.region_to_addr(cp));
1354 const size_t reclaimable = compacted_region_used - compacted_region_live;
1355
1356 const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1357 return double(reclaimable) / divisor;
1358 }
1359
1360 // Return the address of the end of the dense prefix, a.k.a. the start of the
1361 // compacted region. The address is always on a region boundary.
1362 //
1363 // Completely full regions at the left are skipped, since no compaction can
1364 // occur in those regions. Then the maximum amount of dead wood to allow is
1365 // computed, based on the density (amount live / capacity) of the generation;
1366 // the region with approximately that amount of dead space to the left is
1367 // identified as the limit region. Regions between the last completely full
1368 // region and the limit region are scanned and the one that has the best
1369 // (maximum) reclaimed_ratio() is selected.
1370 HeapWord*
1371 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1372 bool maximum_compaction)
1373 {
1374 if (ParallelOldGCSplitALot) {
1375 if (_space_info[id].dense_prefix() != _space_info[id].space()->bottom()) {
1376 // The value was chosen to provoke splitting a young gen space; use it.
1377 return _space_info[id].dense_prefix();
1378 }
1379 }
1380
1381 const size_t region_size = ParallelCompactData::RegionSize;
1382 const ParallelCompactData& sd = summary_data();
1383
1384 const MutableSpace* const space = _space_info[id].space();
1385 HeapWord* const top = space->top();
1386 HeapWord* const top_aligned_up = sd.region_align_up(top);
1387 HeapWord* const new_top = _space_info[id].new_top();
1388 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1389 HeapWord* const bottom = space->bottom();
1390 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1391 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1392 const RegionData* const new_top_cp =
1393 sd.addr_to_region_ptr(new_top_aligned_up);
1394
1395 // Skip full regions at the beginning of the space--they are necessarily part
1396 // of the dense prefix.
1397 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1398 assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1399 space->is_empty(), "no dead space allowed to the left");
1400 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1401 "region must have dead space");
1402
1403 // The gc number is saved whenever a maximum compaction is done, and used to
1404 // determine when the maximum compaction interval has expired. This avoids
1405 // successive max compactions for different reasons.
1406 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1407 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1408 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1409 total_invocations() == HeapFirstMaximumCompactionCount;
1410 if (maximum_compaction || full_cp == top_cp || interval_ended) {
1411 _maximum_compaction_gc_num = total_invocations();
1412 return sd.region_to_addr(full_cp);
1413 }
1414
1415 const size_t space_live = pointer_delta(new_top, bottom);
1416 const size_t space_used = space->used_in_words();
1417 const size_t space_capacity = space->capacity_in_words();
1418
1419 const double density = double(space_live) / double(space_capacity);
1420 const size_t min_percent_free = MarkSweepDeadRatio;
1421 const double limiter = dead_wood_limiter(density, min_percent_free);
1422 const size_t dead_wood_max = space_used - space_live;
1423 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1424 dead_wood_max);
1425
1426 if (TraceParallelOldGCDensePrefix) {
1427 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1428 "space_cap=" SIZE_FORMAT,
1429 space_live, space_used,
1430 space_capacity);
1431 tty->print_cr("dead_wood_limiter(%6.4f, %d)=%6.4f "
1432 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1433 density, min_percent_free, limiter,
1434 dead_wood_max, dead_wood_limit);
1435 }
1436
1437 // Locate the region with the desired amount of dead space to the left.
1438 const RegionData* const limit_cp =
1439 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1440
1441 // Scan from the first region with dead space to the limit region and find the
1442 // one with the best (largest) reclaimed ratio.
1443 double best_ratio = 0.0;
1444 const RegionData* best_cp = full_cp;
1445 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1446 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1447 if (tmp_ratio > best_ratio) {
1448 best_cp = cp;
1449 best_ratio = tmp_ratio;
1450 }
1451 }
1452
1453 #if 0
1454 // Something to consider: if the region with the best ratio is 'close to' the
1455 // first region w/free space, choose the first region with free space
1456 // ("first-free"). The first-free region is usually near the start of the
1457 // heap, which means we are copying most of the heap already, so copy a bit
1458 // more to get complete compaction.
1459 if (pointer_delta(best_cp, full_cp, sizeof(RegionData)) < 4) {
1460 _maximum_compaction_gc_num = total_invocations();
1461 best_cp = full_cp;
1462 }
1463 #endif // #if 0
1464
1465 return sd.region_to_addr(best_cp);
1466 }
1467
1468 #ifndef PRODUCT
1469 void
1470 PSParallelCompact::fill_with_live_objects(SpaceId id, HeapWord* const start,
1471 size_t words)
1472 {
1473 if (TraceParallelOldGCSummaryPhase) {
1474 tty->print_cr("fill_with_live_objects [" PTR_FORMAT " " PTR_FORMAT ") "
1475 SIZE_FORMAT, start, start + words, words);
1476 }
1477
1478 ObjectStartArray* const start_array = _space_info[id].start_array();
1479 CollectedHeap::fill_with_objects(start, words);
1480 for (HeapWord* p = start; p < start + words; p += oop(p)->size()) {
1481 _mark_bitmap.mark_obj(p, words);
1482 _summary_data.add_obj(p, words);
1483 start_array->allocate_block(p);
1484 }
1485 }
1486
1487 void
1488 PSParallelCompact::summarize_new_objects(SpaceId id, HeapWord* start)
1489 {
1490 ParallelCompactData& sd = summary_data();
1491 MutableSpace* space = _space_info[id].space();
1492
1493 // Find the source and destination start addresses.
1494 HeapWord* const src_addr = sd.region_align_down(start);
1495 HeapWord* dst_addr;
1496 if (src_addr < start) {
1497 dst_addr = sd.addr_to_region_ptr(src_addr)->destination();
1498 } else if (src_addr > space->bottom()) {
1499 // The start (the original top() value) is aligned to a region boundary so
1500 // the associated region does not have a destination. Compute the
1501 // destination from the previous region.
1502 RegionData* const cp = sd.addr_to_region_ptr(src_addr) - 1;
1503 dst_addr = cp->destination() + cp->data_size();
1504 } else {
1505 // Filling the entire space.
1506 dst_addr = space->bottom();
1507 }
1508 assert(dst_addr != NULL, "sanity");
1509
1510 // Update the summary data.
1511 bool result = _summary_data.summarize(_space_info[id].split_info(),
1512 src_addr, space->top(), NULL,
1513 dst_addr, space->end(),
1514 _space_info[id].new_top_addr());
1515 assert(result, "should not fail: bad filler object size");
1516 }
1517
1518 void
1519 PSParallelCompact::provoke_split_fill_survivor(SpaceId id)
1520 {
1521 if (total_invocations() % (ParallelOldGCSplitInterval * 3) != 0) {
1522 return;
1523 }
1524
1525 MutableSpace* const space = _space_info[id].space();
1526 if (space->is_empty()) {
1527 HeapWord* b = space->bottom();
1528 HeapWord* t = b + space->capacity_in_words() / 2;
1529 space->set_top(t);
1530 if (ZapUnusedHeapArea) {
1531 space->set_top_for_allocations();
1532 }
1533
1534 size_t min_size = CollectedHeap::min_fill_size();
1535 size_t obj_len = min_size;
1536 while (b + obj_len <= t) {
1537 CollectedHeap::fill_with_object(b, obj_len);
1538 mark_bitmap()->mark_obj(b, obj_len);
1539 summary_data().add_obj(b, obj_len);
1540 b += obj_len;
1541 obj_len = (obj_len & (min_size*3)) + min_size; // 8 16 24 32 8 16 24 32 ...
1542 }
1543 if (b < t) {
1544 // The loop didn't completely fill to t (top); adjust top downward.
1545 space->set_top(b);
1546 if (ZapUnusedHeapArea) {
1547 space->set_top_for_allocations();
1548 }
1549 }
1550
1551 HeapWord** nta = _space_info[id].new_top_addr();
1552 bool result = summary_data().summarize(_space_info[id].split_info(),
1553 space->bottom(), space->top(), NULL,
1554 space->bottom(), space->end(), nta);
1555 assert(result, "space must fit into itself");
1556 }
1557 }
1558
1559 void
1560 PSParallelCompact::provoke_split(bool & max_compaction)
1561 {
1562 if (total_invocations() % ParallelOldGCSplitInterval != 0) {
1563 return;
1564 }
1565
1566 const size_t region_size = ParallelCompactData::RegionSize;
1567 ParallelCompactData& sd = summary_data();
1568
1569 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1570 MutableSpace* const from_space = _space_info[from_space_id].space();
1571 const size_t eden_live = pointer_delta(eden_space->top(),
1572 _space_info[eden_space_id].new_top());
1573 const size_t from_live = pointer_delta(from_space->top(),
1574 _space_info[from_space_id].new_top());
1575
1576 const size_t min_fill_size = CollectedHeap::min_fill_size();
1577 const size_t eden_free = pointer_delta(eden_space->end(), eden_space->top());
1578 const size_t eden_fillable = eden_free >= min_fill_size ? eden_free : 0;
1579 const size_t from_free = pointer_delta(from_space->end(), from_space->top());
1580 const size_t from_fillable = from_free >= min_fill_size ? from_free : 0;
1581
1582 // Choose the space to split; need at least 2 regions live (or fillable).
1583 SpaceId id;
1584 MutableSpace* space;
1585 size_t live_words;
1586 size_t fill_words;
1587 if (eden_live + eden_fillable >= region_size * 2) {
1588 id = eden_space_id;
1589 space = eden_space;
1590 live_words = eden_live;
1591 fill_words = eden_fillable;
1592 } else if (from_live + from_fillable >= region_size * 2) {
1593 id = from_space_id;
1594 space = from_space;
1595 live_words = from_live;
1596 fill_words = from_fillable;
1597 } else {
1598 return; // Give up.
1599 }
1600 assert(fill_words == 0 || fill_words >= min_fill_size, "sanity");
1601
1602 if (live_words < region_size * 2) {
1603 // Fill from top() to end() w/live objects of mixed sizes.
1604 HeapWord* const fill_start = space->top();
1605 live_words += fill_words;
1606
1607 space->set_top(fill_start + fill_words);
1608 if (ZapUnusedHeapArea) {
1609 space->set_top_for_allocations();
1610 }
1611
1612 HeapWord* cur_addr = fill_start;
1613 while (fill_words > 0) {
1614 const size_t r = (size_t)os::random() % (region_size / 2) + min_fill_size;
1615 size_t cur_size = MIN2(align_object_size_(r), fill_words);
1616 if (fill_words - cur_size < min_fill_size) {
1617 cur_size = fill_words; // Avoid leaving a fragment too small to fill.
1618 }
1619
1620 CollectedHeap::fill_with_object(cur_addr, cur_size);
1621 mark_bitmap()->mark_obj(cur_addr, cur_size);
1622 sd.add_obj(cur_addr, cur_size);
1623
1624 cur_addr += cur_size;
1625 fill_words -= cur_size;
1626 }
1627
1628 summarize_new_objects(id, fill_start);
1629 }
1630
1631 max_compaction = false;
1632
1633 // Manipulate the old gen so that it has room for about half of the live data
1634 // in the target young gen space (live_words / 2).
1635 id = old_space_id;
1636 space = _space_info[id].space();
1637 const size_t free_at_end = space->free_in_words();
1638 const size_t free_target = align_object_size(live_words / 2);
1639 const size_t dead = pointer_delta(space->top(), _space_info[id].new_top());
1640
1641 if (free_at_end >= free_target + min_fill_size) {
1642 // Fill space above top() and set the dense prefix so everything survives.
1643 HeapWord* const fill_start = space->top();
1644 const size_t fill_size = free_at_end - free_target;
1645 space->set_top(space->top() + fill_size);
1646 if (ZapUnusedHeapArea) {
1647 space->set_top_for_allocations();
1648 }
1649 fill_with_live_objects(id, fill_start, fill_size);
1650 summarize_new_objects(id, fill_start);
1651 _space_info[id].set_dense_prefix(sd.region_align_down(space->top()));
1652 } else if (dead + free_at_end > free_target) {
1653 // Find a dense prefix that makes the right amount of space available.
1654 HeapWord* cur = sd.region_align_down(space->top());
1655 HeapWord* cur_destination = sd.addr_to_region_ptr(cur)->destination();
1656 size_t dead_to_right = pointer_delta(space->end(), cur_destination);
1657 while (dead_to_right < free_target) {
1658 cur -= region_size;
1659 cur_destination = sd.addr_to_region_ptr(cur)->destination();
1660 dead_to_right = pointer_delta(space->end(), cur_destination);
1661 }
1662 _space_info[id].set_dense_prefix(cur);
1663 }
1664 }
1665 #endif // #ifndef PRODUCT
1666
1667 void PSParallelCompact::summarize_spaces_quick()
1668 {
1669 for (unsigned int i = 0; i < last_space_id; ++i) {
1670 const MutableSpace* space = _space_info[i].space();
1671 HeapWord** nta = _space_info[i].new_top_addr();
1672 bool result = _summary_data.summarize(_space_info[i].split_info(),
1673 space->bottom(), space->top(), NULL,
1674 space->bottom(), space->end(), nta);
1675 assert(result, "space must fit into itself");
1676 _space_info[i].set_dense_prefix(space->bottom());
1677 }
1678
1679 #ifndef PRODUCT
1680 if (ParallelOldGCSplitALot) {
1681 provoke_split_fill_survivor(to_space_id);
1682 }
1683 #endif // #ifndef PRODUCT
1684 }
1685
1686 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1687 {
1688 HeapWord* const dense_prefix_end = dense_prefix(id);
1689 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1690 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1691 if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1692 // Only enough dead space is filled so that any remaining dead space to the
1693 // left is larger than the minimum filler object. (The remainder is filled
1694 // during the copy/update phase.)
1695 //
1696 // The size of the dead space to the right of the boundary is not a
1697 // concern, since compaction will be able to use whatever space is
1698 // available.
1699 //
1700 // Here '||' is the boundary, 'x' represents a don't care bit and a box
1701 // surrounds the space to be filled with an object.
1702 //
1703 // In the 32-bit VM, each bit represents two 32-bit words:
1704 // +---+
1705 // a) beg_bits: ... x x x | 0 | || 0 x x ...
1706 // end_bits: ... x x x | 0 | || 0 x x ...
1707 // +---+
1708 //
1709 // In the 64-bit VM, each bit represents one 64-bit word:
1710 // +------------+
1711 // b) beg_bits: ... x x x | 0 || 0 | x x ...
1712 // end_bits: ... x x 1 | 0 || 0 | x x ...
1713 // +------------+
1714 // +-------+
1715 // c) beg_bits: ... x x | 0 0 | || 0 x x ...
1716 // end_bits: ... x 1 | 0 0 | || 0 x x ...
1717 // +-------+
1718 // +-----------+
1719 // d) beg_bits: ... x | 0 0 0 | || 0 x x ...
1720 // end_bits: ... 1 | 0 0 0 | || 0 x x ...
1721 // +-----------+
1722 // +-------+
1723 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ...
1724 // end_bits: ... 0 0 | 0 0 | || 0 x x ...
1725 // +-------+
1726
1727 // Initially assume case a, c or e will apply.
1728 size_t obj_len = CollectedHeap::min_fill_size();
1729 HeapWord* obj_beg = dense_prefix_end - obj_len;
1730
1731 #ifdef _LP64
1732 if (MinObjAlignment > 1) { // object alignment > heap word size
1733 // Cases a, c or e.
1734 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1735 // Case b above.
1736 obj_beg = dense_prefix_end - 1;
1737 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1738 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1739 // Case d above.
1740 obj_beg = dense_prefix_end - 3;
1741 obj_len = 3;
1742 }
1743 #endif // #ifdef _LP64
1744
1745 CollectedHeap::fill_with_object(obj_beg, obj_len);
1746 _mark_bitmap.mark_obj(obj_beg, obj_len);
1747 _summary_data.add_obj(obj_beg, obj_len);
1748 assert(start_array(id) != NULL, "sanity");
1749 start_array(id)->allocate_block(obj_beg);
1750 }
1751 }
1752
1753 void
1754 PSParallelCompact::clear_source_region(HeapWord* beg_addr, HeapWord* end_addr)
1755 {
1756 RegionData* const beg_ptr = _summary_data.addr_to_region_ptr(beg_addr);
1757 HeapWord* const end_aligned_up = _summary_data.region_align_up(end_addr);
1758 RegionData* const end_ptr = _summary_data.addr_to_region_ptr(end_aligned_up);
1759 for (RegionData* cur = beg_ptr; cur < end_ptr; ++cur) {
1760 cur->set_source_region(0);
1761 }
1762 }
1763
1764 void
1765 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1766 {
1767 assert(id < last_space_id, "id out of range");
1768 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom() ||
1769 ParallelOldGCSplitALot && id == old_space_id,
1770 "should have been reset in summarize_spaces_quick()");
1771
1772 const MutableSpace* space = _space_info[id].space();
1773 if (_space_info[id].new_top() != space->bottom()) {
1774 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1775 _space_info[id].set_dense_prefix(dense_prefix_end);
1776
1777 #ifndef PRODUCT
1778 if (TraceParallelOldGCDensePrefix) {
1779 print_dense_prefix_stats("ratio", id, maximum_compaction,
1780 dense_prefix_end);
1781 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1782 print_dense_prefix_stats("density", id, maximum_compaction, addr);
1783 }
1784 #endif // #ifndef PRODUCT
1785
1786 // Recompute the summary data, taking into account the dense prefix. If
1787 // every last byte will be reclaimed, then the existing summary data which
1788 // compacts everything can be left in place.
1789 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1790 // If dead space crosses the dense prefix boundary, it is (at least
1791 // partially) filled with a dummy object, marked live and added to the
1792 // summary data. This simplifies the copy/update phase and must be done
1793 // before the final locations of objects are determined, to prevent
1794 // leaving a fragment of dead space that is too small to fill.
1795 fill_dense_prefix_end(id);
1796
1797 // Compute the destination of each Region, and thus each object.
1798 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1799 _summary_data.summarize(_space_info[id].split_info(),
1800 dense_prefix_end, space->top(), NULL,
1801 dense_prefix_end, space->end(),
1802 _space_info[id].new_top_addr());
1803 }
1804 }
1805
1806 if (TraceParallelOldGCSummaryPhase) {
1807 const size_t region_size = ParallelCompactData::RegionSize;
1808 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1809 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1810 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1811 HeapWord* const new_top = _space_info[id].new_top();
1812 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1813 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1814 tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1815 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1816 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1817 id, space->capacity_in_words(), dense_prefix_end,
1818 dp_region, dp_words / region_size,
1819 cr_words / region_size, new_top);
1820 }
1821 }
1822
1823 #ifndef PRODUCT
1824 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1825 HeapWord* dst_beg, HeapWord* dst_end,
1826 SpaceId src_space_id,
1827 HeapWord* src_beg, HeapWord* src_end)
1828 {
1829 if (TraceParallelOldGCSummaryPhase) {
1830 tty->print_cr("summarizing %d [%s] into %d [%s]: "
1831 "src=" PTR_FORMAT "-" PTR_FORMAT " "
1832 SIZE_FORMAT "-" SIZE_FORMAT " "
1833 "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1834 SIZE_FORMAT "-" SIZE_FORMAT,
1835 src_space_id, space_names[src_space_id],
1836 dst_space_id, space_names[dst_space_id],
1837 src_beg, src_end,
1838 _summary_data.addr_to_region_idx(src_beg),
1839 _summary_data.addr_to_region_idx(src_end),
1840 dst_beg, dst_end,
1841 _summary_data.addr_to_region_idx(dst_beg),
1842 _summary_data.addr_to_region_idx(dst_end));
1843 }
1844 }
1845 #endif // #ifndef PRODUCT
1846
1847 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1848 bool maximum_compaction)
1849 {
1850 GCTraceTime tm("summary phase", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
1851 // trace("2");
1852
1853 #ifdef ASSERT
1854 if (TraceParallelOldGCMarkingPhase) {
1855 tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1856 "add_obj_bytes=" SIZE_FORMAT,
1857 add_obj_count, add_obj_size * HeapWordSize);
1858 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1859 "mark_bitmap_bytes=" SIZE_FORMAT,
1860 mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1861 }
1862 #endif // #ifdef ASSERT
1863
1864 // Quick summarization of each space into itself, to see how much is live.
1865 summarize_spaces_quick();
1866
1867 if (TraceParallelOldGCSummaryPhase) {
1868 tty->print_cr("summary_phase: after summarizing each space to self");
1869 Universe::print();
1870 NOT_PRODUCT(print_region_ranges());
1871 if (Verbose) {
1872 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1873 }
1874 }
1875
1876 // The amount of live data that will end up in old space (assuming it fits).
1877 size_t old_space_total_live = 0;
1878 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1879 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1880 _space_info[id].space()->bottom());
1881 }
1882
1883 MutableSpace* const old_space = _space_info[old_space_id].space();
1884 const size_t old_capacity = old_space->capacity_in_words();
1885 if (old_space_total_live > old_capacity) {
1886 // XXX - should also try to expand
1887 maximum_compaction = true;
1888 }
1889 #ifndef PRODUCT
1890 if (ParallelOldGCSplitALot && old_space_total_live < old_capacity) {
1891 provoke_split(maximum_compaction);
1892 }
1893 #endif // #ifndef PRODUCT
1894
1895 // Old generations.
1896 summarize_space(old_space_id, maximum_compaction);
1897
1898 // Summarize the remaining spaces in the young gen. The initial target space
1899 // is the old gen. If a space does not fit entirely into the target, then the
1900 // remainder is compacted into the space itself and that space becomes the new
1901 // target.
1902 SpaceId dst_space_id = old_space_id;
1903 HeapWord* dst_space_end = old_space->end();
1904 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1905 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1906 const MutableSpace* space = _space_info[id].space();
1907 const size_t live = pointer_delta(_space_info[id].new_top(),
1908 space->bottom());
1909 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1910
1911 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1912 SpaceId(id), space->bottom(), space->top());)
1913 if (live > 0 && live <= available) {
1914 // All the live data will fit.
1915 bool done = _summary_data.summarize(_space_info[id].split_info(),
1916 space->bottom(), space->top(),
1917 NULL,
1918 *new_top_addr, dst_space_end,
1919 new_top_addr);
1920 assert(done, "space must fit into old gen");
1921
1922 // Reset the new_top value for the space.
1923 _space_info[id].set_new_top(space->bottom());
1924 } else if (live > 0) {
1925 // Attempt to fit part of the source space into the target space.
1926 HeapWord* next_src_addr = NULL;
1927 bool done = _summary_data.summarize(_space_info[id].split_info(),
1928 space->bottom(), space->top(),
1929 &next_src_addr,
1930 *new_top_addr, dst_space_end,
1931 new_top_addr);
1932 assert(!done, "space should not fit into old gen");
1933 assert(next_src_addr != NULL, "sanity");
1934
1935 // The source space becomes the new target, so the remainder is compacted
1936 // within the space itself.
1937 dst_space_id = SpaceId(id);
1938 dst_space_end = space->end();
1939 new_top_addr = _space_info[id].new_top_addr();
1940 NOT_PRODUCT(summary_phase_msg(dst_space_id,
1941 space->bottom(), dst_space_end,
1942 SpaceId(id), next_src_addr, space->top());)
1943 done = _summary_data.summarize(_space_info[id].split_info(),
1944 next_src_addr, space->top(),
1945 NULL,
1946 space->bottom(), dst_space_end,
1947 new_top_addr);
1948 assert(done, "space must fit when compacted into itself");
1949 assert(*new_top_addr <= space->top(), "usage should not grow");
1950 }
1951 }
1952
1953 if (TraceParallelOldGCSummaryPhase) {
1954 tty->print_cr("summary_phase: after final summarization");
1955 Universe::print();
1956 NOT_PRODUCT(print_region_ranges());
1957 if (Verbose) {
1958 NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info));
1959 }
1960 }
1961 }
1962
1963 // This method should contain all heap-specific policy for invoking a full
1964 // collection. invoke_no_policy() will only attempt to compact the heap; it
1965 // will do nothing further. If we need to bail out for policy reasons, scavenge
1966 // before full gc, or any other specialized behavior, it needs to be added here.
1967 //
1968 // Note that this method should only be called from the vm_thread while at a
1969 // safepoint.
1970 //
1971 // Note that the all_soft_refs_clear flag in the collector policy
1972 // may be true because this method can be called without intervening
1973 // activity. For example when the heap space is tight and full measure
1974 // are being taken to free space.
1975 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1976 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1977 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1978 "should be in vm thread");
1979
1980 ParallelScavengeHeap* heap = gc_heap();
1981 GCCause::Cause gc_cause = heap->gc_cause();
1982 assert(!heap->is_gc_active(), "not reentrant");
1983
1984 PSAdaptiveSizePolicy* policy = heap->size_policy();
1985 IsGCActiveMark mark;
1986
1987 if (ScavengeBeforeFullGC) {
1988 PSScavenge::invoke_no_policy();
1989 }
1990
1991 const bool clear_all_soft_refs =
1992 heap->collector_policy()->should_clear_all_soft_refs();
1993
1994 PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1995 maximum_heap_compaction);
1996 }
1997
1998 // This method contains no policy. You should probably
1999 // be calling invoke() instead.
2000 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
2001 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
2002 assert(ref_processor() != NULL, "Sanity");
2003
2004 if (GC_locker::check_active_before_gc()) {
2005 return false;
2006 }
2007
2008 ParallelScavengeHeap* heap = gc_heap();
2009
2010 _gc_timer.register_gc_start();
2011 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
2012
2013 TimeStamp marking_start;
2014 TimeStamp compaction_start;
2015 TimeStamp collection_exit;
2016
2017 GCCause::Cause gc_cause = heap->gc_cause();
2018 PSYoungGen* young_gen = heap->young_gen();
2019 PSOldGen* old_gen = heap->old_gen();
2020 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
2021
2022 // The scope of casr should end after code that can change
2023 // CollectorPolicy::_should_clear_all_soft_refs.
2024 ClearedAllSoftRefs casr(maximum_heap_compaction,
2025 heap->collector_policy());
2026
2027 if (ZapUnusedHeapArea) {
2028 // Save information needed to minimize mangling
2029 heap->record_gen_tops_before_GC();
2030 }
2031
2032 heap->pre_full_gc_dump(&_gc_timer);
2033
2034 _print_phases = PrintGCDetails && PrintParallelOldGCPhaseTimes;
2035
2036 // Make sure data structures are sane, make the heap parsable, and do other
2037 // miscellaneous bookkeeping.
2038 PreGCValues pre_gc_values;
2039 pre_compact(&pre_gc_values);
2040
2041 // Get the compaction manager reserved for the VM thread.
2042 ParCompactionManager* const vmthread_cm =
2043 ParCompactionManager::manager_array(gc_task_manager()->workers());
2044
2045 // Place after pre_compact() where the number of invocations is incremented.
2046 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
2047
2048 {
2049 ResourceMark rm;
2050 HandleMark hm;
2051
2052 // Set the number of GC threads to be used in this collection
2053 gc_task_manager()->set_active_gang();
2054 gc_task_manager()->task_idle_workers();
2055 heap->set_par_threads(gc_task_manager()->active_workers());
2056
2057 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2058 GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL, _gc_tracer.gc_id());
2059 TraceCollectorStats tcs(counters());
2060 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
2061
2062 if (TraceGen1Time) accumulated_time()->start();
2063
2064 // Let the size policy know we're starting
2065 size_policy->major_collection_begin();
2066
2067 CodeCache::gc_prologue();
2068 Threads::gc_prologue();
2069
2070 COMPILER2_PRESENT(DerivedPointerTable::clear());
2071
2072 ref_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
2073 ref_processor()->setup_policy(maximum_heap_compaction);
2074
2075 bool marked_for_unloading = false;
2076
2077 marking_start.update();
2078 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer);
2079
2080 bool max_on_system_gc = UseMaximumCompactionOnSystemGC
2081 && gc_cause == GCCause::_java_lang_system_gc;
2082 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
2083
2084 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
2085 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
2086
2087 // adjust_roots() updates Universe::_intArrayKlassObj which is
2088 // needed by the compaction for filling holes in the dense prefix.
2089 adjust_roots();
2090
2091 compaction_start.update();
2092 compact();
2093
2094 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
2095 // done before resizing.
2096 post_compact();
2097
2098 // Let the size policy know we're done
2099 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
2100
2101 if (UseAdaptiveSizePolicy) {
2102 if (PrintAdaptiveSizePolicy) {
2103 gclog_or_tty->print("AdaptiveSizeStart: ");
2104 gclog_or_tty->stamp();
2105 gclog_or_tty->print_cr(" collection: %d ",
2106 heap->total_collections());
2107 if (Verbose) {
2108 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d",
2109 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
2110 }
2111 }
2112
2113 // Don't check if the size_policy is ready here. Let
2114 // the size_policy check that internally.
2115 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
2116 ((gc_cause != GCCause::_java_lang_system_gc) ||
2117 UseAdaptiveSizePolicyWithSystemGC)) {
2118 // Calculate optimal free space amounts
2119 assert(young_gen->max_size() >
2120 young_gen->from_space()->capacity_in_bytes() +
2121 young_gen->to_space()->capacity_in_bytes(),
2122 "Sizes of space in young gen are out-of-bounds");
2123
2124 size_t young_live = young_gen->used_in_bytes();
2125 size_t eden_live = young_gen->eden_space()->used_in_bytes();
2126 size_t old_live = old_gen->used_in_bytes();
2127 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
2128 size_t max_old_gen_size = old_gen->max_gen_size();
2129 size_t max_eden_size = young_gen->max_size() -
2130 young_gen->from_space()->capacity_in_bytes() -
2131 young_gen->to_space()->capacity_in_bytes();
2132
2133 // Used for diagnostics
2134 size_policy->clear_generation_free_space_flags();
2135
2136 size_policy->compute_generations_free_space(young_live,
2137 eden_live,
2138 old_live,
2139 cur_eden,
2140 max_old_gen_size,
2141 max_eden_size,
2142 true /* full gc*/);
2143
2144 size_policy->check_gc_overhead_limit(young_live,
2145 eden_live,
2146 max_old_gen_size,
2147 max_eden_size,
2148 true /* full gc*/,
2149 gc_cause,
2150 heap->collector_policy());
2151
2152 size_policy->decay_supplemental_growth(true /* full gc*/);
2153
2154 heap->resize_old_gen(
2155 size_policy->calculated_old_free_size_in_bytes());
2156
2157 // Don't resize the young generation at an major collection. A
2158 // desired young generation size may have been calculated but
2159 // resizing the young generation complicates the code because the
2160 // resizing of the old generation may have moved the boundary
2161 // between the young generation and the old generation. Let the
2162 // young generation resizing happen at the minor collections.
2163 }
2164 if (PrintAdaptiveSizePolicy) {
2165 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
2166 heap->total_collections());
2167 }
2168 }
2169
2170 if (UsePerfData) {
2171 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
2172 counters->update_counters();
2173 counters->update_old_capacity(old_gen->capacity_in_bytes());
2174 counters->update_young_capacity(young_gen->capacity_in_bytes());
2175 }
2176
2177 heap->resize_all_tlabs();
2178
2179 // Resize the metaspace capactiy after a collection
2180 MetaspaceGC::compute_new_size();
2181
2182 if (TraceGen1Time) accumulated_time()->stop();
2183
2184 if (PrintGC) {
2185 if (PrintGCDetails) {
2186 // No GC timestamp here. This is after GC so it would be confusing.
2187 young_gen->print_used_change(pre_gc_values.young_gen_used());
2188 old_gen->print_used_change(pre_gc_values.old_gen_used());
2189 heap->print_heap_change(pre_gc_values.heap_used());
2190 MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used());
2191 } else {
2192 heap->print_heap_change(pre_gc_values.heap_used());
2193 }
2194 }
2195
2196 // Track memory usage and detect low memory
2197 MemoryService::track_memory_usage();
2198 heap->update_counters();
2199 gc_task_manager()->release_idle_workers();
2200 }
2201
2202 #ifdef ASSERT
2203 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
2204 ParCompactionManager* const cm =
2205 ParCompactionManager::manager_array(int(i));
2206 assert(cm->marking_stack()->is_empty(), "should be empty");
2207 assert(ParCompactionManager::region_list(int(i))->is_empty(), "should be empty");
2208 }
2209 #endif // ASSERT
2210
2211 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
2212 HandleMark hm; // Discard invalid handles created during verification
2213 Universe::verify(" VerifyAfterGC:");
2214 }
2215
2216 // Re-verify object start arrays
2217 if (VerifyObjectStartArray &&
2218 VerifyAfterGC) {
2219 old_gen->verify_object_start_array();
2220 }
2221
2222 if (ZapUnusedHeapArea) {
2223 old_gen->object_space()->check_mangled_unused_area_complete();
2224 }
2225
2226 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
2227
2228 collection_exit.update();
2229
2230 heap->print_heap_after_gc();
2231 heap->trace_heap_after_gc(&_gc_tracer);
2232
2233 if (PrintGCTaskTimeStamps) {
2234 gclog_or_tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " "
2235 INT64_FORMAT,
2236 marking_start.ticks(), compaction_start.ticks(),
2237 collection_exit.ticks());
2238 gc_task_manager()->print_task_time_stamps();
2239 }
2240
2241 heap->post_full_gc_dump(&_gc_timer);
2242
2243 #ifdef TRACESPINNING
2244 ParallelTaskTerminator::print_termination_counts();
2245 #endif
2246
2247 _gc_timer.register_gc_end();
2248
2249 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
2250 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
2251
2252 return true;
2253 }
2254
2255 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
2256 PSYoungGen* young_gen,
2257 PSOldGen* old_gen) {
2258 MutableSpace* const eden_space = young_gen->eden_space();
2259 assert(!eden_space->is_empty(), "eden must be non-empty");
2260 assert(young_gen->virtual_space()->alignment() ==
2261 old_gen->virtual_space()->alignment(), "alignments do not match");
2262
2263 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
2264 return false;
2265 }
2266
2267 // Both generations must be completely committed.
2268 if (young_gen->virtual_space()->uncommitted_size() != 0) {
2269 return false;
2270 }
2271 if (old_gen->virtual_space()->uncommitted_size() != 0) {
2272 return false;
2273 }
2274
2275 // Figure out how much to take from eden. Include the average amount promoted
2276 // in the total; otherwise the next young gen GC will simply bail out to a
2277 // full GC.
2278 const size_t alignment = old_gen->virtual_space()->alignment();
2279 const size_t eden_used = eden_space->used_in_bytes();
2280 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
2281 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
2282 const size_t eden_capacity = eden_space->capacity_in_bytes();
2283
2284 if (absorb_size >= eden_capacity) {
2285 return false; // Must leave some space in eden.
2286 }
2287
2288 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2289 if (new_young_size < young_gen->min_gen_size()) {
2290 return false; // Respect young gen minimum size.
2291 }
2292
2293 if (TraceAdaptiveGCBoundary && Verbose) {
2294 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
2295 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2296 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2297 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2298 absorb_size / K,
2299 eden_capacity / K, (eden_capacity - absorb_size) / K,
2300 young_gen->from_space()->used_in_bytes() / K,
2301 young_gen->to_space()->used_in_bytes() / K,
2302 young_gen->capacity_in_bytes() / K, new_young_size / K);
2303 }
2304
2305 // Fill the unused part of the old gen.
2306 MutableSpace* const old_space = old_gen->object_space();
2307 HeapWord* const unused_start = old_space->top();
2308 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2309
2310 if (unused_words > 0) {
2311 if (unused_words < CollectedHeap::min_fill_size()) {
2312 return false; // If the old gen cannot be filled, must give up.
2313 }
2314 CollectedHeap::fill_with_objects(unused_start, unused_words);
2315 }
2316
2317 // Take the live data from eden and set both top and end in the old gen to
2318 // eden top. (Need to set end because reset_after_change() mangles the region
2319 // from end to virtual_space->high() in debug builds).
2320 HeapWord* const new_top = eden_space->top();
2321 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2322 absorb_size);
2323 young_gen->reset_after_change();
2324 old_space->set_top(new_top);
2325 old_space->set_end(new_top);
2326 old_gen->reset_after_change();
2327
2328 // Update the object start array for the filler object and the data from eden.
2329 ObjectStartArray* const start_array = old_gen->start_array();
2330 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2331 start_array->allocate_block(p);
2332 }
2333
2334 // Could update the promoted average here, but it is not typically updated at
2335 // full GCs and the value to use is unclear. Something like
2336 //
2337 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2338
2339 size_policy->set_bytes_absorbed_from_eden(absorb_size);
2340 return true;
2341 }
2342
2343 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2344 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2345 "shouldn't return NULL");
2346 return ParallelScavengeHeap::gc_task_manager();
2347 }
2348
2349 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2350 bool maximum_heap_compaction,
2351 ParallelOldTracer *gc_tracer) {
2352 // Recursively traverse all live objects and mark them
2353 GCTraceTime tm("marking phase", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2354
2355 ParallelScavengeHeap* heap = gc_heap();
2356 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2357 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2358 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2359 ParallelTaskTerminator terminator(active_gc_threads, qset);
2360
2361 PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
2362 PSParallelCompact::FollowStackClosure follow_stack_closure(cm);
2363
2364 // Need new claim bits before marking starts.
2365 ClassLoaderDataGraph::clear_claimed_marks();
2366
2367 {
2368 GCTraceTime tm_m("par mark", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2369
2370 ParallelScavengeHeap::ParStrongRootsScope psrs;
2371
2372 GCTaskQueue* q = GCTaskQueue::create();
2373
2374 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2375 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2376 // We scan the thread roots in parallel
2377 Threads::create_thread_roots_marking_tasks(q);
2378 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2379 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
2380 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2381 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2382 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data));
2383 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2384 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2385
2386 if (active_gc_threads > 1) {
2387 for (uint j = 0; j < active_gc_threads; j++) {
2388 q->enqueue(new StealMarkingTask(&terminator));
2389 }
2390 }
2391
2392 gc_task_manager()->execute_and_wait(q);
2393 }
2394
2395 // Process reference objects found during marking
2396 {
2397 GCTraceTime tm_r("reference processing", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2398
2399 ReferenceProcessorStats stats;
2400 if (ref_processor()->processing_is_mt()) {
2401 RefProcTaskExecutor task_executor;
2402 stats = ref_processor()->process_discovered_references(
2403 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2404 &task_executor, &_gc_timer, _gc_tracer.gc_id());
2405 } else {
2406 stats = ref_processor()->process_discovered_references(
2407 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
2408 &_gc_timer, _gc_tracer.gc_id());
2409 }
2410
2411 gc_tracer->report_gc_reference_stats(stats);
2412 }
2413
2414 GCTraceTime tm_c("class unloading", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2415
2416 // This is the point where the entire marking should have completed.
2417 assert(cm->marking_stacks_empty(), "Marking should have completed");
2418
2419 // Follow system dictionary roots and unload classes.
2420 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
2421
2422 // Unload nmethods.
2423 CodeCache::do_unloading(is_alive_closure(), purged_class);
2424
2425 // Prune dead klasses from subklass/sibling/implementor lists.
2426 Klass::clean_weak_klass_links(is_alive_closure());
2427
2428 // Delete entries for dead interned strings.
2429 StringTable::unlink(is_alive_closure());
2430
2431 // Clean up unreferenced symbols in symbol table.
2432 SymbolTable::unlink();
2433 _gc_tracer.report_object_count_after_gc(is_alive_closure());
2434 }
2435
2436 void PSParallelCompact::follow_class_loader(ParCompactionManager* cm,
2437 ClassLoaderData* cld) {
2438 PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
2439 PSParallelCompact::FollowKlassClosure follow_klass_closure(&mark_and_push_closure);
2440
2441 cld->oops_do(&mark_and_push_closure, &follow_klass_closure, true);
2442 }
2443
2444 // This should be moved to the shared markSweep code!
2445 class PSAlwaysTrueClosure: public BoolObjectClosure {
2446 public:
2447 bool do_object_b(oop p) { return true; }
2448 };
2449 static PSAlwaysTrueClosure always_true;
2450
2451 void PSParallelCompact::adjust_roots() {
2452 // Adjust the pointers to reflect the new locations
2453 GCTraceTime tm("adjust roots", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2454
2455 // Need new claim bits when tracing through and adjusting pointers.
2456 ClassLoaderDataGraph::clear_claimed_marks();
2457
2458 // General strong roots.
2459 Universe::oops_do(adjust_pointer_closure());
2460 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
2461 CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
2462 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
2463 ObjectSynchronizer::oops_do(adjust_pointer_closure());
2464 FlatProfiler::oops_do(adjust_pointer_closure());
2465 Management::oops_do(adjust_pointer_closure());
2466 JvmtiExport::oops_do(adjust_pointer_closure());
2467 SystemDictionary::oops_do(adjust_pointer_closure());
2468 ClassLoaderDataGraph::oops_do(adjust_pointer_closure(), adjust_klass_closure(), true);
2469
2470 // Now adjust pointers in remaining weak roots. (All of which should
2471 // have been cleared if they pointed to non-surviving objects.)
2472 // Global (weak) JNI handles
2473 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure());
2474
2475 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations);
2476 CodeCache::blobs_do(&adjust_from_blobs);
2477 StringTable::oops_do(adjust_pointer_closure());
2478 ref_processor()->weak_oops_do(adjust_pointer_closure());
2479 // Roots were visited so references into the young gen in roots
2480 // may have been scanned. Process them also.
2481 // Should the reference processor have a span that excludes
2482 // young gen objects?
2483 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
2484 }
2485
2486 void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q,
2487 uint parallel_gc_threads)
2488 {
2489 GCTraceTime tm("drain task setup", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2490
2491 // Find the threads that are active
2492 unsigned int which = 0;
2493
2494 const uint task_count = MAX2(parallel_gc_threads, 1U);
2495 for (uint j = 0; j < task_count; j++) {
2496 q->enqueue(new DrainStacksCompactionTask(j));
2497 ParCompactionManager::verify_region_list_empty(j);
2498 // Set the region stacks variables to "no" region stack values
2499 // so that they will be recognized and needing a region stack
2500 // in the stealing tasks if they do not get one by executing
2501 // a draining stack.
2502 ParCompactionManager* cm = ParCompactionManager::manager_array(j);
2503 cm->set_region_stack(NULL);
2504 cm->set_region_stack_index((uint)max_uintx);
2505 }
2506 ParCompactionManager::reset_recycled_stack_index();
2507
2508 // Find all regions that are available (can be filled immediately) and
2509 // distribute them to the thread stacks. The iteration is done in reverse
2510 // order (high to low) so the regions will be removed in ascending order.
2511
2512 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2513
2514 size_t fillable_regions = 0; // A count for diagnostic purposes.
2515 // A region index which corresponds to the tasks created above.
2516 // "which" must be 0 <= which < task_count
2517
2518 which = 0;
2519 // id + 1 is used to test termination so unsigned can
2520 // be used with an old_space_id == 0.
2521 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2522 SpaceInfo* const space_info = _space_info + id;
2523 MutableSpace* const space = space_info->space();
2524 HeapWord* const new_top = space_info->new_top();
2525
2526 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2527 const size_t end_region =
2528 sd.addr_to_region_idx(sd.region_align_up(new_top));
2529
2530 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2531 if (sd.region(cur)->claim_unsafe()) {
2532 ParCompactionManager::region_list_push(which, cur);
2533
2534 if (TraceParallelOldGCCompactionPhase && Verbose) {
2535 const size_t count_mod_8 = fillable_regions & 7;
2536 if (count_mod_8 == 0) gclog_or_tty->print("fillable: ");
2537 gclog_or_tty->print(" " SIZE_FORMAT_W(7), cur);
2538 if (count_mod_8 == 7) gclog_or_tty->cr();
2539 }
2540
2541 NOT_PRODUCT(++fillable_regions;)
2542
2543 // Assign regions to tasks in round-robin fashion.
2544 if (++which == task_count) {
2545 assert(which <= parallel_gc_threads,
2546 "Inconsistent number of workers");
2547 which = 0;
2548 }
2549 }
2550 }
2551 }
2552
2553 if (TraceParallelOldGCCompactionPhase) {
2554 if (Verbose && (fillable_regions & 7) != 0) gclog_or_tty->cr();
2555 gclog_or_tty->print_cr("%u initially fillable regions", fillable_regions);
2556 }
2557 }
2558
2559 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2560
2561 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2562 uint parallel_gc_threads) {
2563 GCTraceTime tm("dense prefix task setup", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2564
2565 ParallelCompactData& sd = PSParallelCompact::summary_data();
2566
2567 // Iterate over all the spaces adding tasks for updating
2568 // regions in the dense prefix. Assume that 1 gc thread
2569 // will work on opening the gaps and the remaining gc threads
2570 // will work on the dense prefix.
2571 unsigned int space_id;
2572 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2573 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2574 const MutableSpace* const space = _space_info[space_id].space();
2575
2576 if (dense_prefix_end == space->bottom()) {
2577 // There is no dense prefix for this space.
2578 continue;
2579 }
2580
2581 // The dense prefix is before this region.
2582 size_t region_index_end_dense_prefix =
2583 sd.addr_to_region_idx(dense_prefix_end);
2584 RegionData* const dense_prefix_cp =
2585 sd.region(region_index_end_dense_prefix);
2586 assert(dense_prefix_end == space->end() ||
2587 dense_prefix_cp->available() ||
2588 dense_prefix_cp->claimed(),
2589 "The region after the dense prefix should always be ready to fill");
2590
2591 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2592
2593 // Is there dense prefix work?
2594 size_t total_dense_prefix_regions =
2595 region_index_end_dense_prefix - region_index_start;
2596 // How many regions of the dense prefix should be given to
2597 // each thread?
2598 if (total_dense_prefix_regions > 0) {
2599 uint tasks_for_dense_prefix = 1;
2600 if (total_dense_prefix_regions <=
2601 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2602 // Don't over partition. This assumes that
2603 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2604 // so there are not many regions to process.
2605 tasks_for_dense_prefix = parallel_gc_threads;
2606 } else {
2607 // Over partition
2608 tasks_for_dense_prefix = parallel_gc_threads *
2609 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2610 }
2611 size_t regions_per_thread = total_dense_prefix_regions /
2612 tasks_for_dense_prefix;
2613 // Give each thread at least 1 region.
2614 if (regions_per_thread == 0) {
2615 regions_per_thread = 1;
2616 }
2617
2618 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2619 if (region_index_start >= region_index_end_dense_prefix) {
2620 break;
2621 }
2622 // region_index_end is not processed
2623 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2624 region_index_end_dense_prefix);
2625 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2626 region_index_start,
2627 region_index_end));
2628 region_index_start = region_index_end;
2629 }
2630 }
2631 // This gets any part of the dense prefix that did not
2632 // fit evenly.
2633 if (region_index_start < region_index_end_dense_prefix) {
2634 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2635 region_index_start,
2636 region_index_end_dense_prefix));
2637 }
2638 }
2639 }
2640
2641 void PSParallelCompact::enqueue_region_stealing_tasks(
2642 GCTaskQueue* q,
2643 ParallelTaskTerminator* terminator_ptr,
2644 uint parallel_gc_threads) {
2645 GCTraceTime tm("steal task setup", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2646
2647 // Once a thread has drained it's stack, it should try to steal regions from
2648 // other threads.
2649 if (parallel_gc_threads > 1) {
2650 for (uint j = 0; j < parallel_gc_threads; j++) {
2651 q->enqueue(new StealRegionCompactionTask(terminator_ptr));
2652 }
2653 }
2654 }
2655
2656 #ifdef ASSERT
2657 // Write a histogram of the number of times the block table was filled for a
2658 // region.
2659 void PSParallelCompact::write_block_fill_histogram(outputStream* const out)
2660 {
2661 if (!TraceParallelOldGCCompactionPhase) return;
2662
2663 typedef ParallelCompactData::RegionData rd_t;
2664 ParallelCompactData& sd = summary_data();
2665
2666 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2667 MutableSpace* const spc = _space_info[id].space();
2668 if (spc->bottom() != spc->top()) {
2669 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
2670 HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
2671 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
2672
2673 size_t histo[5] = { 0, 0, 0, 0, 0 };
2674 const size_t histo_len = sizeof(histo) / sizeof(size_t);
2675 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
2676
2677 for (const rd_t* cur = beg; cur < end; ++cur) {
2678 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
2679 }
2680 out->print("%u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
2681 for (size_t i = 0; i < histo_len; ++i) {
2682 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
2683 histo[i], 100.0 * histo[i] / region_cnt);
2684 }
2685 out->cr();
2686 }
2687 }
2688 }
2689 #endif // #ifdef ASSERT
2690
2691 void PSParallelCompact::compact() {
2692 // trace("5");
2693 GCTraceTime tm("compaction phase", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2694
2695 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
2696 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
2697 PSOldGen* old_gen = heap->old_gen();
2698 old_gen->start_array()->reset();
2699 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2700 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2701 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2702 ParallelTaskTerminator terminator(active_gc_threads, qset);
2703
2704 GCTaskQueue* q = GCTaskQueue::create();
2705 enqueue_region_draining_tasks(q, active_gc_threads);
2706 enqueue_dense_prefix_tasks(q, active_gc_threads);
2707 enqueue_region_stealing_tasks(q, &terminator, active_gc_threads);
2708
2709 {
2710 GCTraceTime tm_pc("par compact", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2711
2712 gc_task_manager()->execute_and_wait(q);
2713
2714 #ifdef ASSERT
2715 // Verify that all regions have been processed before the deferred updates.
2716 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2717 verify_complete(SpaceId(id));
2718 }
2719 #endif
2720 }
2721
2722 {
2723 // Update the deferred objects, if any. Any compaction manager can be used.
2724 GCTraceTime tm_du("deferred updates", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2725 ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2726 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2727 update_deferred_objects(cm, SpaceId(id));
2728 }
2729 }
2730
2731 DEBUG_ONLY(write_block_fill_histogram(gclog_or_tty));
2732 }
2733
2734 #ifdef ASSERT
2735 void PSParallelCompact::verify_complete(SpaceId space_id) {
2736 // All Regions between space bottom() to new_top() should be marked as filled
2737 // and all Regions between new_top() and top() should be available (i.e.,
2738 // should have been emptied).
2739 ParallelCompactData& sd = summary_data();
2740 SpaceInfo si = _space_info[space_id];
2741 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2742 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2743 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2744 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2745 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2746
2747 bool issued_a_warning = false;
2748
2749 size_t cur_region;
2750 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2751 const RegionData* const c = sd.region(cur_region);
2752 if (!c->completed()) {
2753 warning("region " SIZE_FORMAT " not filled: "
2754 "destination_count=" SIZE_FORMAT,
2755 cur_region, c->destination_count());
2756 issued_a_warning = true;
2757 }
2758 }
2759
2760 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2761 const RegionData* const c = sd.region(cur_region);
2762 if (!c->available()) {
2763 warning("region " SIZE_FORMAT " not empty: "
2764 "destination_count=" SIZE_FORMAT,
2765 cur_region, c->destination_count());
2766 issued_a_warning = true;
2767 }
2768 }
2769
2770 if (issued_a_warning) {
2771 print_region_ranges();
2772 }
2773 }
2774 #endif // #ifdef ASSERT
2775
2776 // Update interior oops in the ranges of regions [beg_region, end_region).
2777 void
2778 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2779 SpaceId space_id,
2780 size_t beg_region,
2781 size_t end_region) {
2782 ParallelCompactData& sd = summary_data();
2783 ParMarkBitMap* const mbm = mark_bitmap();
2784
2785 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2786 HeapWord* const end_addr = sd.region_to_addr(end_region);
2787 assert(beg_region <= end_region, "bad region range");
2788 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2789
2790 #ifdef ASSERT
2791 // Claim the regions to avoid triggering an assert when they are marked as
2792 // filled.
2793 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2794 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2795 }
2796 #endif // #ifdef ASSERT
2797
2798 if (beg_addr != space(space_id)->bottom()) {
2799 // Find the first live object or block of dead space that *starts* in this
2800 // range of regions. If a partial object crosses onto the region, skip it;
2801 // it will be marked for 'deferred update' when the object head is
2802 // processed. If dead space crosses onto the region, it is also skipped; it
2803 // will be filled when the prior region is processed. If neither of those
2804 // apply, the first word in the region is the start of a live object or dead
2805 // space.
2806 assert(beg_addr > space(space_id)->bottom(), "sanity");
2807 const RegionData* const cp = sd.region(beg_region);
2808 if (cp->partial_obj_size() != 0) {
2809 beg_addr = sd.partial_obj_end(beg_region);
2810 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2811 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2812 }
2813 }
2814
2815 if (beg_addr < end_addr) {
2816 // A live object or block of dead space starts in this range of Regions.
2817 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2818
2819 // Create closures and iterate.
2820 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2821 FillClosure fill_closure(cm, space_id);
2822 ParMarkBitMap::IterationStatus status;
2823 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2824 dense_prefix_end);
2825 if (status == ParMarkBitMap::incomplete) {
2826 update_closure.do_addr(update_closure.source());
2827 }
2828 }
2829
2830 // Mark the regions as filled.
2831 RegionData* const beg_cp = sd.region(beg_region);
2832 RegionData* const end_cp = sd.region(end_region);
2833 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2834 cp->set_completed();
2835 }
2836 }
2837
2838 // Return the SpaceId for the space containing addr. If addr is not in the
2839 // heap, last_space_id is returned. In debug mode it expects the address to be
2840 // in the heap and asserts such.
2841 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2842 assert(Universe::heap()->is_in_reserved(addr), "addr not in the heap");
2843
2844 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2845 if (_space_info[id].space()->contains(addr)) {
2846 return SpaceId(id);
2847 }
2848 }
2849
2850 assert(false, "no space contains the addr");
2851 return last_space_id;
2852 }
2853
2854 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2855 SpaceId id) {
2856 assert(id < last_space_id, "bad space id");
2857
2858 ParallelCompactData& sd = summary_data();
2859 const SpaceInfo* const space_info = _space_info + id;
2860 ObjectStartArray* const start_array = space_info->start_array();
2861
2862 const MutableSpace* const space = space_info->space();
2863 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2864 HeapWord* const beg_addr = space_info->dense_prefix();
2865 HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2866
2867 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2868 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2869 const RegionData* cur_region;
2870 for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2871 HeapWord* const addr = cur_region->deferred_obj_addr();
2872 if (addr != NULL) {
2873 if (start_array != NULL) {
2874 start_array->allocate_block(addr);
2875 }
2876 oop(addr)->update_contents(cm);
2877 assert(oop(addr)->is_oop_or_null(), "should be an oop now");
2878 }
2879 }
2880 }
2881
2882 // Skip over count live words starting from beg, and return the address of the
2883 // next live word. Unless marked, the word corresponding to beg is assumed to
2884 // be dead. Callers must either ensure beg does not correspond to the middle of
2885 // an object, or account for those live words in some other way. Callers must
2886 // also ensure that there are enough live words in the range [beg, end) to skip.
2887 HeapWord*
2888 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2889 {
2890 assert(count > 0, "sanity");
2891
2892 ParMarkBitMap* m = mark_bitmap();
2893 idx_t bits_to_skip = m->words_to_bits(count);
2894 idx_t cur_beg = m->addr_to_bit(beg);
2895 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
2896
2897 do {
2898 cur_beg = m->find_obj_beg(cur_beg, search_end);
2899 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2900 const size_t obj_bits = cur_end - cur_beg + 1;
2901 if (obj_bits > bits_to_skip) {
2902 return m->bit_to_addr(cur_beg + bits_to_skip);
2903 }
2904 bits_to_skip -= obj_bits;
2905 cur_beg = cur_end + 1;
2906 } while (bits_to_skip > 0);
2907
2908 // Skipping the desired number of words landed just past the end of an object.
2909 // Find the start of the next object.
2910 cur_beg = m->find_obj_beg(cur_beg, search_end);
2911 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2912 return m->bit_to_addr(cur_beg);
2913 }
2914
2915 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2916 SpaceId src_space_id,
2917 size_t src_region_idx)
2918 {
2919 assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2920
2921 const SplitInfo& split_info = _space_info[src_space_id].split_info();
2922 if (split_info.dest_region_addr() == dest_addr) {
2923 // The partial object ending at the split point contains the first word to
2924 // be copied to dest_addr.
2925 return split_info.first_src_addr();
2926 }
2927
2928 const ParallelCompactData& sd = summary_data();
2929 ParMarkBitMap* const bitmap = mark_bitmap();
2930 const size_t RegionSize = ParallelCompactData::RegionSize;
2931
2932 assert(sd.is_region_aligned(dest_addr), "not aligned");
2933 const RegionData* const src_region_ptr = sd.region(src_region_idx);
2934 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2935 HeapWord* const src_region_destination = src_region_ptr->destination();
2936
2937 assert(dest_addr >= src_region_destination, "wrong src region");
2938 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2939
2940 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2941 HeapWord* const src_region_end = src_region_beg + RegionSize;
2942
2943 HeapWord* addr = src_region_beg;
2944 if (dest_addr == src_region_destination) {
2945 // Return the first live word in the source region.
2946 if (partial_obj_size == 0) {
2947 addr = bitmap->find_obj_beg(addr, src_region_end);
2948 assert(addr < src_region_end, "no objects start in src region");
2949 }
2950 return addr;
2951 }
2952
2953 // Must skip some live data.
2954 size_t words_to_skip = dest_addr - src_region_destination;
2955 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2956
2957 if (partial_obj_size >= words_to_skip) {
2958 // All the live words to skip are part of the partial object.
2959 addr += words_to_skip;
2960 if (partial_obj_size == words_to_skip) {
2961 // Find the first live word past the partial object.
2962 addr = bitmap->find_obj_beg(addr, src_region_end);
2963 assert(addr < src_region_end, "wrong src region");
2964 }
2965 return addr;
2966 }
2967
2968 // Skip over the partial object (if any).
2969 if (partial_obj_size != 0) {
2970 words_to_skip -= partial_obj_size;
2971 addr += partial_obj_size;
2972 }
2973
2974 // Skip over live words due to objects that start in the region.
2975 addr = skip_live_words(addr, src_region_end, words_to_skip);
2976 assert(addr < src_region_end, "wrong src region");
2977 return addr;
2978 }
2979
2980 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2981 SpaceId src_space_id,
2982 size_t beg_region,
2983 HeapWord* end_addr)
2984 {
2985 ParallelCompactData& sd = summary_data();
2986
2987 #ifdef ASSERT
2988 MutableSpace* const src_space = _space_info[src_space_id].space();
2989 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2990 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2991 "src_space_id does not match beg_addr");
2992 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2993 "src_space_id does not match end_addr");
2994 #endif // #ifdef ASSERT
2995
2996 RegionData* const beg = sd.region(beg_region);
2997 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2998
2999 // Regions up to new_top() are enqueued if they become available.
3000 HeapWord* const new_top = _space_info[src_space_id].new_top();
3001 RegionData* const enqueue_end =
3002 sd.addr_to_region_ptr(sd.region_align_up(new_top));
3003
3004 for (RegionData* cur = beg; cur < end; ++cur) {
3005 assert(cur->data_size() > 0, "region must have live data");
3006 cur->decrement_destination_count();
3007 if (cur < enqueue_end && cur->available() && cur->claim()) {
3008 cm->push_region(sd.region(cur));
3009 }
3010 }
3011 }
3012
3013 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
3014 SpaceId& src_space_id,
3015 HeapWord*& src_space_top,
3016 HeapWord* end_addr)
3017 {
3018 typedef ParallelCompactData::RegionData RegionData;
3019
3020 ParallelCompactData& sd = PSParallelCompact::summary_data();
3021 const size_t region_size = ParallelCompactData::RegionSize;
3022
3023 size_t src_region_idx = 0;
3024
3025 // Skip empty regions (if any) up to the top of the space.
3026 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
3027 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
3028 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
3029 const RegionData* const top_region_ptr =
3030 sd.addr_to_region_ptr(top_aligned_up);
3031 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
3032 ++src_region_ptr;
3033 }
3034
3035 if (src_region_ptr < top_region_ptr) {
3036 // The next source region is in the current space. Update src_region_idx
3037 // and the source address to match src_region_ptr.
3038 src_region_idx = sd.region(src_region_ptr);
3039 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
3040 if (src_region_addr > closure.source()) {
3041 closure.set_source(src_region_addr);
3042 }
3043 return src_region_idx;
3044 }
3045
3046 // Switch to a new source space and find the first non-empty region.
3047 unsigned int space_id = src_space_id + 1;
3048 assert(space_id < last_space_id, "not enough spaces");
3049
3050 HeapWord* const destination = closure.destination();
3051
3052 do {
3053 MutableSpace* space = _space_info[space_id].space();
3054 HeapWord* const bottom = space->bottom();
3055 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
3056
3057 // Iterate over the spaces that do not compact into themselves.
3058 if (bottom_cp->destination() != bottom) {
3059 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
3060 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
3061
3062 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
3063 if (src_cp->live_obj_size() > 0) {
3064 // Found it.
3065 assert(src_cp->destination() == destination,
3066 "first live obj in the space must match the destination");
3067 assert(src_cp->partial_obj_size() == 0,
3068 "a space cannot begin with a partial obj");
3069
3070 src_space_id = SpaceId(space_id);
3071 src_space_top = space->top();
3072 const size_t src_region_idx = sd.region(src_cp);
3073 closure.set_source(sd.region_to_addr(src_region_idx));
3074 return src_region_idx;
3075 } else {
3076 assert(src_cp->data_size() == 0, "sanity");
3077 }
3078 }
3079 }
3080 } while (++space_id < last_space_id);
3081
3082 assert(false, "no source region was found");
3083 return 0;
3084 }
3085
3086 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
3087 {
3088 typedef ParMarkBitMap::IterationStatus IterationStatus;
3089 const size_t RegionSize = ParallelCompactData::RegionSize;
3090 ParMarkBitMap* const bitmap = mark_bitmap();
3091 ParallelCompactData& sd = summary_data();
3092 RegionData* const region_ptr = sd.region(region_idx);
3093
3094 // Get the items needed to construct the closure.
3095 HeapWord* dest_addr = sd.region_to_addr(region_idx);
3096 SpaceId dest_space_id = space_id(dest_addr);
3097 ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
3098 HeapWord* new_top = _space_info[dest_space_id].new_top();
3099 assert(dest_addr < new_top, "sanity");
3100 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
3101
3102 // Get the source region and related info.
3103 size_t src_region_idx = region_ptr->source_region();
3104 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
3105 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
3106
3107 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3108 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
3109
3110 // Adjust src_region_idx to prepare for decrementing destination counts (the
3111 // destination count is not decremented when a region is copied to itself).
3112 if (src_region_idx == region_idx) {
3113 src_region_idx += 1;
3114 }
3115
3116 if (bitmap->is_unmarked(closure.source())) {
3117 // The first source word is in the middle of an object; copy the remainder
3118 // of the object or as much as will fit. The fact that pointer updates were
3119 // deferred will be noted when the object header is processed.
3120 HeapWord* const old_src_addr = closure.source();
3121 closure.copy_partial_obj();
3122 if (closure.is_full()) {
3123 decrement_destination_counts(cm, src_space_id, src_region_idx,
3124 closure.source());
3125 region_ptr->set_deferred_obj_addr(NULL);
3126 region_ptr->set_completed();
3127 return;
3128 }
3129
3130 HeapWord* const end_addr = sd.region_align_down(closure.source());
3131 if (sd.region_align_down(old_src_addr) != end_addr) {
3132 // The partial object was copied from more than one source region.
3133 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3134
3135 // Move to the next source region, possibly switching spaces as well. All
3136 // args except end_addr may be modified.
3137 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3138 end_addr);
3139 }
3140 }
3141
3142 do {
3143 HeapWord* const cur_addr = closure.source();
3144 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
3145 src_space_top);
3146 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
3147
3148 if (status == ParMarkBitMap::incomplete) {
3149 // The last obj that starts in the source region does not end in the
3150 // region.
3151 assert(closure.source() < end_addr, "sanity");
3152 HeapWord* const obj_beg = closure.source();
3153 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
3154 src_space_top);
3155 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
3156 if (obj_end < range_end) {
3157 // The end was found; the entire object will fit.
3158 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
3159 assert(status != ParMarkBitMap::would_overflow, "sanity");
3160 } else {
3161 // The end was not found; the object will not fit.
3162 assert(range_end < src_space_top, "obj cannot cross space boundary");
3163 status = ParMarkBitMap::would_overflow;
3164 }
3165 }
3166
3167 if (status == ParMarkBitMap::would_overflow) {
3168 // The last object did not fit. Note that interior oop updates were
3169 // deferred, then copy enough of the object to fill the region.
3170 region_ptr->set_deferred_obj_addr(closure.destination());
3171 status = closure.copy_until_full(); // copies from closure.source()
3172
3173 decrement_destination_counts(cm, src_space_id, src_region_idx,
3174 closure.source());
3175 region_ptr->set_completed();
3176 return;
3177 }
3178
3179 if (status == ParMarkBitMap::full) {
3180 decrement_destination_counts(cm, src_space_id, src_region_idx,
3181 closure.source());
3182 region_ptr->set_deferred_obj_addr(NULL);
3183 region_ptr->set_completed();
3184 return;
3185 }
3186
3187 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3188
3189 // Move to the next source region, possibly switching spaces as well. All
3190 // args except end_addr may be modified.
3191 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3192 end_addr);
3193 } while (true);
3194 }
3195
3196 void PSParallelCompact::fill_blocks(size_t region_idx)
3197 {
3198 // Fill in the block table elements for the specified region. Each block
3199 // table element holds the number of live words in the region that are to the
3200 // left of the first object that starts in the block. Thus only blocks in
3201 // which an object starts need to be filled.
3202 //
3203 // The algorithm scans the section of the bitmap that corresponds to the
3204 // region, keeping a running total of the live words. When an object start is
3205 // found, if it's the first to start in the block that contains it, the
3206 // current total is written to the block table element.
3207 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
3208 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
3209 const size_t RegionSize = ParallelCompactData::RegionSize;
3210
3211 ParallelCompactData& sd = summary_data();
3212 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
3213 if (partial_obj_size >= RegionSize) {
3214 return; // No objects start in this region.
3215 }
3216
3217 // Ensure the first loop iteration decides that the block has changed.
3218 size_t cur_block = sd.block_count();
3219
3220 const ParMarkBitMap* const bitmap = mark_bitmap();
3221
3222 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
3223 assert((size_t)1 << Log2BitsPerBlock ==
3224 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
3225
3226 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
3227 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
3228 size_t live_bits = bitmap->words_to_bits(partial_obj_size);
3229 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
3230 while (beg_bit < range_end) {
3231 const size_t new_block = beg_bit >> Log2BitsPerBlock;
3232 if (new_block != cur_block) {
3233 cur_block = new_block;
3234 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
3235 }
3236
3237 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
3238 if (end_bit < range_end - 1) {
3239 live_bits += end_bit - beg_bit + 1;
3240 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
3241 } else {
3242 return;
3243 }
3244 }
3245 }
3246
3247 void
3248 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
3249 const MutableSpace* sp = space(space_id);
3250 if (sp->is_empty()) {
3251 return;
3252 }
3253
3254 ParallelCompactData& sd = PSParallelCompact::summary_data();
3255 ParMarkBitMap* const bitmap = mark_bitmap();
3256 HeapWord* const dp_addr = dense_prefix(space_id);
3257 HeapWord* beg_addr = sp->bottom();
3258 HeapWord* end_addr = sp->top();
3259
3260 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
3261
3262 const size_t beg_region = sd.addr_to_region_idx(beg_addr);
3263 const size_t dp_region = sd.addr_to_region_idx(dp_addr);
3264 if (beg_region < dp_region) {
3265 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
3266 }
3267
3268 // The destination of the first live object that starts in the region is one
3269 // past the end of the partial object entering the region (if any).
3270 HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3271 HeapWord* const new_top = _space_info[space_id].new_top();
3272 assert(new_top >= dest_addr, "bad new_top value");
3273 const size_t words = pointer_delta(new_top, dest_addr);
3274
3275 if (words > 0) {
3276 ObjectStartArray* start_array = _space_info[space_id].start_array();
3277 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3278
3279 ParMarkBitMap::IterationStatus status;
3280 status = bitmap->iterate(&closure, dest_addr, end_addr);
3281 assert(status == ParMarkBitMap::full, "iteration not complete");
3282 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3283 "live objects skipped because closure is full");
3284 }
3285 }
3286
3287 jlong PSParallelCompact::millis_since_last_gc() {
3288 // We need a monotonically non-deccreasing time in ms but
3289 // os::javaTimeMillis() does not guarantee monotonicity.
3290 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3291 jlong ret_val = now - _time_of_last_gc;
3292 // XXX See note in genCollectedHeap::millis_since_last_gc().
3293 if (ret_val < 0) {
3294 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, ret_val);)
3295 return 0;
3296 }
3297 return ret_val;
3298 }
3299
3300 void PSParallelCompact::reset_millis_since_last_gc() {
3301 // We need a monotonically non-deccreasing time in ms but
3302 // os::javaTimeMillis() does not guarantee monotonicity.
3303 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3304 }
3305
3306 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3307 {
3308 if (source() != destination()) {
3309 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3310 Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3311 }
3312 update_state(words_remaining());
3313 assert(is_full(), "sanity");
3314 return ParMarkBitMap::full;
3315 }
3316
3317 void MoveAndUpdateClosure::copy_partial_obj()
3318 {
3319 size_t words = words_remaining();
3320
3321 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3322 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3323 if (end_addr < range_end) {
3324 words = bitmap()->obj_size(source(), end_addr);
3325 }
3326
3327 // This test is necessary; if omitted, the pointer updates to a partial object
3328 // that crosses the dense prefix boundary could be overwritten.
3329 if (source() != destination()) {
3330 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3331 Copy::aligned_conjoint_words(source(), destination(), words);
3332 }
3333 update_state(words);
3334 }
3335
3336 ParMarkBitMapClosure::IterationStatus
3337 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3338 assert(destination() != NULL, "sanity");
3339 assert(bitmap()->obj_size(addr) == words, "bad size");
3340
3341 _source = addr;
3342 assert(PSParallelCompact::summary_data().calc_new_pointer(source()) ==
3343 destination(), "wrong destination");
3344
3345 if (words > words_remaining()) {
3346 return ParMarkBitMap::would_overflow;
3347 }
3348
3349 // The start_array must be updated even if the object is not moving.
3350 if (_start_array != NULL) {
3351 _start_array->allocate_block(destination());
3352 }
3353
3354 if (destination() != source()) {
3355 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3356 Copy::aligned_conjoint_words(source(), destination(), words);
3357 }
3358
3359 oop moved_oop = (oop) destination();
3360 moved_oop->update_contents(compaction_manager());
3361 assert(moved_oop->is_oop_or_null(), "Object should be whole at this point");
3362
3363 update_state(words);
3364 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3365 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3366 }
3367
3368 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3369 ParCompactionManager* cm,
3370 PSParallelCompact::SpaceId space_id) :
3371 ParMarkBitMapClosure(mbm, cm),
3372 _space_id(space_id),
3373 _start_array(PSParallelCompact::start_array(space_id))
3374 {
3375 }
3376
3377 // Updates the references in the object to their new values.
3378 ParMarkBitMapClosure::IterationStatus
3379 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3380 do_addr(addr);
3381 return ParMarkBitMap::incomplete;
3382 }