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/stringTable.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_implementation/shared/spaceDecorator.hpp"
47 #include "gc_interface/gcCause.hpp"
48 #include "memory/gcLocker.inline.hpp"
49 #include "memory/referencePolicy.hpp"
50 #include "memory/referenceProcessor.hpp"
51 #include "oops/methodData.hpp"
52 #include "oops/oop.inline.hpp"
53 #include "oops/oop.pcgc.inline.hpp"
54 #include "runtime/atomic.inline.hpp"
55 #include "runtime/fprofiler.hpp"
56 #include "runtime/safepoint.hpp"
57 #include "runtime/vmThread.hpp"
58 #include "services/management.hpp"
59 #include "services/memoryService.hpp"
60 #include "services/memTracker.hpp"
61 #include "utilities/events.hpp"
62 #include "utilities/stack.inline.hpp"
63
64 #include <math.h>
65
66 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
67
68 // All sizes are in HeapWords.
69 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words
70 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
71 const size_t ParallelCompactData::RegionSizeBytes =
72 RegionSize << LogHeapWordSize;
73 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
74 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
75 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
76
77 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words
78 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize;
79 const size_t ParallelCompactData::BlockSizeBytes =
80 BlockSize << LogHeapWordSize;
81 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1;
82 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1;
83 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask;
84
85 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
86 const size_t ParallelCompactData::Log2BlocksPerRegion =
87 Log2RegionSize - Log2BlockSize;
88
89 const ParallelCompactData::RegionData::region_sz_t
90 ParallelCompactData::RegionData::dc_shift = 27;
91
92 const ParallelCompactData::RegionData::region_sz_t
93 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
94
95 const ParallelCompactData::RegionData::region_sz_t
96 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
97
98 const ParallelCompactData::RegionData::region_sz_t
99 ParallelCompactData::RegionData::los_mask = ~dc_mask;
100
101 const ParallelCompactData::RegionData::region_sz_t
102 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
103
104 const ParallelCompactData::RegionData::region_sz_t
105 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
106
107 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
108 bool PSParallelCompact::_print_phases = false;
109
110 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
111 Klass* PSParallelCompact::_updated_int_array_klass_obj = NULL;
112
113 double PSParallelCompact::_dwl_mean;
114 double PSParallelCompact::_dwl_std_dev;
115 double PSParallelCompact::_dwl_first_term;
116 double PSParallelCompact::_dwl_adjustment;
117 #ifdef ASSERT
118 bool PSParallelCompact::_dwl_initialized = false;
119 #endif // #ifdef ASSERT
120
121 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
122 HeapWord* destination)
123 {
124 assert(src_region_idx != 0, "invalid src_region_idx");
125 assert(partial_obj_size != 0, "invalid partial_obj_size argument");
126 assert(destination != NULL, "invalid destination argument");
127
128 _src_region_idx = src_region_idx;
129 _partial_obj_size = partial_obj_size;
130 _destination = destination;
131
132 // These fields may not be updated below, so make sure they're clear.
133 assert(_dest_region_addr == NULL, "should have been cleared");
134 assert(_first_src_addr == NULL, "should have been cleared");
135
136 // Determine the number of destination regions for the partial object.
137 HeapWord* const last_word = destination + partial_obj_size - 1;
138 const ParallelCompactData& sd = PSParallelCompact::summary_data();
139 HeapWord* const beg_region_addr = sd.region_align_down(destination);
140 HeapWord* const end_region_addr = sd.region_align_down(last_word);
141
142 if (beg_region_addr == end_region_addr) {
143 // One destination region.
144 _destination_count = 1;
145 if (end_region_addr == destination) {
146 // The destination falls on a region boundary, thus the first word of the
147 // partial object will be the first word copied to the destination region.
148 _dest_region_addr = end_region_addr;
149 _first_src_addr = sd.region_to_addr(src_region_idx);
150 }
151 } else {
152 // Two destination regions. When copied, the partial object will cross a
153 // destination region boundary, so a word somewhere within the partial
154 // object will be the first word copied to the second destination region.
155 _destination_count = 2;
156 _dest_region_addr = end_region_addr;
157 const size_t ofs = pointer_delta(end_region_addr, destination);
158 assert(ofs < _partial_obj_size, "sanity");
159 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
160 }
161 }
162
163 void SplitInfo::clear()
164 {
165 _src_region_idx = 0;
166 _partial_obj_size = 0;
167 _destination = NULL;
168 _destination_count = 0;
169 _dest_region_addr = NULL;
170 _first_src_addr = NULL;
171 assert(!is_valid(), "sanity");
172 }
173
174 #ifdef ASSERT
175 void SplitInfo::verify_clear()
176 {
177 assert(_src_region_idx == 0, "not clear");
178 assert(_partial_obj_size == 0, "not clear");
179 assert(_destination == NULL, "not clear");
180 assert(_destination_count == 0, "not clear");
181 assert(_dest_region_addr == NULL, "not clear");
182 assert(_first_src_addr == NULL, "not clear");
183 }
184 #endif // #ifdef ASSERT
185
186
187 void PSParallelCompact::print_on_error(outputStream* st) {
188 _mark_bitmap.print_on_error(st);
189 }
190
191 #ifndef PRODUCT
192 const char* PSParallelCompact::space_names[] = {
193 "old ", "eden", "from", "to "
194 };
195
196 void PSParallelCompact::print_region_ranges()
197 {
198 tty->print_cr("space bottom top end new_top");
199 tty->print_cr("------ ---------- ---------- ---------- ----------");
200
201 for (unsigned int id = 0; id < last_space_id; ++id) {
202 const MutableSpace* space = _space_info[id].space();
203 tty->print_cr("%u %s "
204 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
205 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
206 id, space_names[id],
207 summary_data().addr_to_region_idx(space->bottom()),
208 summary_data().addr_to_region_idx(space->top()),
209 summary_data().addr_to_region_idx(space->end()),
210 summary_data().addr_to_region_idx(_space_info[id].new_top()));
211 }
212 }
213
214 void
215 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
216 {
217 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7)
218 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5)
219
220 ParallelCompactData& sd = PSParallelCompact::summary_data();
221 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
222 tty->print_cr(REGION_IDX_FORMAT " " PTR_FORMAT " "
223 REGION_IDX_FORMAT " " PTR_FORMAT " "
224 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
225 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
226 i, c->data_location(), dci, c->destination(),
227 c->partial_obj_size(), c->live_obj_size(),
228 c->data_size(), c->source_region(), c->destination_count());
229
230 #undef REGION_IDX_FORMAT
231 #undef REGION_DATA_FORMAT
232 }
233
234 void
235 print_generic_summary_data(ParallelCompactData& summary_data,
236 HeapWord* const beg_addr,
237 HeapWord* const end_addr)
238 {
239 size_t total_words = 0;
240 size_t i = summary_data.addr_to_region_idx(beg_addr);
241 const size_t last = summary_data.addr_to_region_idx(end_addr);
242 HeapWord* pdest = 0;
243
244 while (i <= last) {
245 ParallelCompactData::RegionData* c = summary_data.region(i);
246 if (c->data_size() != 0 || c->destination() != pdest) {
247 print_generic_summary_region(i, c);
248 total_words += c->data_size();
249 pdest = c->destination();
250 }
251 ++i;
252 }
253
254 tty->print_cr("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
255 }
256
257 void
258 print_generic_summary_data(ParallelCompactData& summary_data,
259 SpaceInfo* space_info)
260 {
261 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
262 const MutableSpace* space = space_info[id].space();
263 print_generic_summary_data(summary_data, space->bottom(),
264 MAX2(space->top(), space_info[id].new_top()));
265 }
266 }
267
268 void
269 print_initial_summary_region(size_t i,
270 const ParallelCompactData::RegionData* c,
271 bool newline = true)
272 {
273 tty->print(SIZE_FORMAT_W(5) " " PTR_FORMAT " "
274 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " "
275 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
276 i, c->destination(),
277 c->partial_obj_size(), c->live_obj_size(),
278 c->data_size(), c->source_region(), c->destination_count());
279 if (newline) tty->cr();
280 }
281
282 void
283 print_initial_summary_data(ParallelCompactData& summary_data,
284 const MutableSpace* space) {
285 if (space->top() == space->bottom()) {
286 return;
287 }
288
289 const size_t region_size = ParallelCompactData::RegionSize;
290 typedef ParallelCompactData::RegionData RegionData;
291 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
292 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
293 const RegionData* c = summary_data.region(end_region - 1);
294 HeapWord* end_addr = c->destination() + c->data_size();
295 const size_t live_in_space = pointer_delta(end_addr, space->bottom());
296
297 // Print (and count) the full regions at the beginning of the space.
298 size_t full_region_count = 0;
299 size_t i = summary_data.addr_to_region_idx(space->bottom());
300 while (i < end_region && summary_data.region(i)->data_size() == region_size) {
301 print_initial_summary_region(i, summary_data.region(i));
302 ++full_region_count;
303 ++i;
304 }
305
306 size_t live_to_right = live_in_space - full_region_count * region_size;
307
308 double max_reclaimed_ratio = 0.0;
309 size_t max_reclaimed_ratio_region = 0;
310 size_t max_dead_to_right = 0;
311 size_t max_live_to_right = 0;
312
313 // Print the 'reclaimed ratio' for regions while there is something live in
314 // the region or to the right of it. The remaining regions are empty (and
315 // uninteresting), and computing the ratio will result in division by 0.
316 while (i < end_region && live_to_right > 0) {
317 c = summary_data.region(i);
318 HeapWord* const region_addr = summary_data.region_to_addr(i);
319 const size_t used_to_right = pointer_delta(space->top(), region_addr);
320 const size_t dead_to_right = used_to_right - live_to_right;
321 const double reclaimed_ratio = double(dead_to_right) / live_to_right;
322
323 if (reclaimed_ratio > max_reclaimed_ratio) {
324 max_reclaimed_ratio = reclaimed_ratio;
325 max_reclaimed_ratio_region = i;
326 max_dead_to_right = dead_to_right;
327 max_live_to_right = live_to_right;
328 }
329
330 print_initial_summary_region(i, c, false);
331 tty->print_cr(" %12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
332 reclaimed_ratio, dead_to_right, live_to_right);
333
334 live_to_right -= c->data_size();
335 ++i;
336 }
337
338 // Any remaining regions are empty. Print one more if there is one.
339 if (i < end_region) {
340 print_initial_summary_region(i, summary_data.region(i));
341 }
342
343 tty->print_cr("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " "
344 "l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
345 max_reclaimed_ratio_region, max_dead_to_right,
346 max_live_to_right, max_reclaimed_ratio);
347 }
348
349 void
350 print_initial_summary_data(ParallelCompactData& summary_data,
351 SpaceInfo* space_info) {
352 unsigned int id = PSParallelCompact::old_space_id;
353 const MutableSpace* space;
354 do {
355 space = space_info[id].space();
356 print_initial_summary_data(summary_data, space);
357 } while (++id < PSParallelCompact::eden_space_id);
358
359 do {
360 space = space_info[id].space();
361 print_generic_summary_data(summary_data, space->bottom(), space->top());
362 } while (++id < PSParallelCompact::last_space_id);
363 }
364 #endif // #ifndef PRODUCT
365
366 #ifdef ASSERT
367 size_t add_obj_count;
368 size_t add_obj_size;
369 size_t mark_bitmap_count;
370 size_t mark_bitmap_size;
371 #endif // #ifdef ASSERT
372
373 ParallelCompactData::ParallelCompactData()
374 {
375 _region_start = 0;
376
377 _region_vspace = 0;
378 _reserved_byte_size = 0;
379 _region_data = 0;
380 _region_count = 0;
381
382 _block_vspace = 0;
383 _block_data = 0;
384 _block_count = 0;
385 }
386
387 bool ParallelCompactData::initialize(MemRegion covered_region)
388 {
389 _region_start = covered_region.start();
390 const size_t region_size = covered_region.word_size();
391 DEBUG_ONLY(_region_end = _region_start + region_size;)
392
393 assert(region_align_down(_region_start) == _region_start,
394 "region start not aligned");
395 assert((region_size & RegionSizeOffsetMask) == 0,
396 "region size not a multiple of RegionSize");
397
398 bool result = initialize_region_data(region_size) && initialize_block_data();
399 return result;
400 }
401
402 PSVirtualSpace*
403 ParallelCompactData::create_vspace(size_t count, size_t element_size)
404 {
405 const size_t raw_bytes = count * element_size;
406 const size_t page_sz = os::page_size_for_region(raw_bytes, raw_bytes, 10);
407 const size_t granularity = os::vm_allocation_granularity();
408 _reserved_byte_size = align_size_up(raw_bytes, MAX2(page_sz, granularity));
409
410 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
411 MAX2(page_sz, granularity);
412 ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0);
413 os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(),
414 rs.size());
415
416 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
417
418 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
419 if (vspace != 0) {
420 if (vspace->expand_by(_reserved_byte_size)) {
421 return vspace;
422 }
423 delete vspace;
424 // Release memory reserved in the space.
425 rs.release();
426 }
427
428 return 0;
429 }
430
431 bool ParallelCompactData::initialize_region_data(size_t region_size)
432 {
433 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
434 _region_vspace = create_vspace(count, sizeof(RegionData));
435 if (_region_vspace != 0) {
436 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
437 _region_count = count;
438 return true;
439 }
440 return false;
441 }
442
443 bool ParallelCompactData::initialize_block_data()
444 {
445 assert(_region_count != 0, "region data must be initialized first");
446 const size_t count = _region_count << Log2BlocksPerRegion;
447 _block_vspace = create_vspace(count, sizeof(BlockData));
448 if (_block_vspace != 0) {
449 _block_data = (BlockData*)_block_vspace->reserved_low_addr();
450 _block_count = count;
451 return true;
452 }
453 return false;
454 }
455
456 void ParallelCompactData::clear()
457 {
458 memset(_region_data, 0, _region_vspace->committed_size());
459 memset(_block_data, 0, _block_vspace->committed_size());
460 }
461
462 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
463 assert(beg_region <= _region_count, "beg_region out of range");
464 assert(end_region <= _region_count, "end_region out of range");
465 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize");
466
467 const size_t region_cnt = end_region - beg_region;
468 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
469
470 const size_t beg_block = beg_region * BlocksPerRegion;
471 const size_t block_cnt = region_cnt * BlocksPerRegion;
472 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));
473 }
474
475 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
476 {
477 const RegionData* cur_cp = region(region_idx);
478 const RegionData* const end_cp = region(region_count() - 1);
479
480 HeapWord* result = region_to_addr(region_idx);
481 if (cur_cp < end_cp) {
482 do {
483 result += cur_cp->partial_obj_size();
484 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
485 }
486 return result;
487 }
488
489 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
490 {
491 const size_t obj_ofs = pointer_delta(addr, _region_start);
492 const size_t beg_region = obj_ofs >> Log2RegionSize;
493 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
494
495 DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
496 DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
497
498 if (beg_region == end_region) {
499 // All in one region.
500 _region_data[beg_region].add_live_obj(len);
501 return;
502 }
503
504 // First region.
505 const size_t beg_ofs = region_offset(addr);
506 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
507
508 Klass* klass = ((oop)addr)->klass();
509 // Middle regions--completely spanned by this object.
510 for (size_t region = beg_region + 1; region < end_region; ++region) {
511 _region_data[region].set_partial_obj_size(RegionSize);
512 _region_data[region].set_partial_obj_addr(addr);
513 }
514
515 // Last region.
516 const size_t end_ofs = region_offset(addr + len - 1);
517 _region_data[end_region].set_partial_obj_size(end_ofs + 1);
518 _region_data[end_region].set_partial_obj_addr(addr);
519 }
520
521 void
522 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
523 {
524 assert(region_offset(beg) == 0, "not RegionSize aligned");
525 assert(region_offset(end) == 0, "not RegionSize aligned");
526
527 size_t cur_region = addr_to_region_idx(beg);
528 const size_t end_region = addr_to_region_idx(end);
529 HeapWord* addr = beg;
530 while (cur_region < end_region) {
531 _region_data[cur_region].set_destination(addr);
532 _region_data[cur_region].set_destination_count(0);
533 _region_data[cur_region].set_source_region(cur_region);
534 _region_data[cur_region].set_data_location(addr);
535
536 // Update live_obj_size so the region appears completely full.
537 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
538 _region_data[cur_region].set_live_obj_size(live_size);
539
540 ++cur_region;
541 addr += RegionSize;
542 }
543 }
544
545 // Find the point at which a space can be split and, if necessary, record the
546 // split point.
547 //
548 // If the current src region (which overflowed the destination space) doesn't
549 // have a partial object, the split point is at the beginning of the current src
550 // region (an "easy" split, no extra bookkeeping required).
551 //
552 // If the current src region has a partial object, the split point is in the
553 // region where that partial object starts (call it the split_region). If
554 // split_region has a partial object, then the split point is just after that
555 // partial object (a "hard" split where we have to record the split data and
556 // zero the partial_obj_size field). With a "hard" split, we know that the
557 // partial_obj ends within split_region because the partial object that caused
558 // the overflow starts in split_region. If split_region doesn't have a partial
559 // obj, then the split is at the beginning of split_region (another "easy"
560 // split).
561 HeapWord*
562 ParallelCompactData::summarize_split_space(size_t src_region,
563 SplitInfo& split_info,
564 HeapWord* destination,
565 HeapWord* target_end,
566 HeapWord** target_next)
567 {
568 assert(destination <= target_end, "sanity");
569 assert(destination + _region_data[src_region].data_size() > target_end,
570 "region should not fit into target space");
571 assert(is_region_aligned(target_end), "sanity");
572
573 size_t split_region = src_region;
574 HeapWord* split_destination = destination;
575 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
576
577 if (destination + partial_obj_size > target_end) {
578 // The split point is just after the partial object (if any) in the
579 // src_region that contains the start of the object that overflowed the
580 // destination space.
581 //
582 // Find the start of the "overflow" object and set split_region to the
583 // region containing it.
584 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
585 split_region = addr_to_region_idx(overflow_obj);
586
587 // Clear the source_region field of all destination regions whose first word
588 // came from data after the split point (a non-null source_region field
589 // implies a region must be filled).
590 //
591 // An alternative to the simple loop below: clear during post_compact(),
592 // which uses memcpy instead of individual stores, and is easy to
593 // parallelize. (The downside is that it clears the entire RegionData
594 // object as opposed to just one field.)
595 //
596 // post_compact() would have to clear the summary data up to the highest
597 // address that was written during the summary phase, which would be
598 //
599 // max(top, max(new_top, clear_top))
600 //
601 // where clear_top is a new field in SpaceInfo. Would have to set clear_top
602 // to target_end.
603 const RegionData* const sr = region(split_region);
604 const size_t beg_idx =
605 addr_to_region_idx(region_align_up(sr->destination() +
606 sr->partial_obj_size()));
607 const size_t end_idx = addr_to_region_idx(target_end);
608
609 if (TraceParallelOldGCSummaryPhase) {
610 gclog_or_tty->print_cr("split: clearing source_region field in ["
611 SIZE_FORMAT ", " SIZE_FORMAT ")",
612 beg_idx, end_idx);
613 }
614 for (size_t idx = beg_idx; idx < end_idx; ++idx) {
615 _region_data[idx].set_source_region(0);
616 }
617
618 // Set split_destination and partial_obj_size to reflect the split region.
619 split_destination = sr->destination();
620 partial_obj_size = sr->partial_obj_size();
621 }
622
623 // The split is recorded only if a partial object extends onto the region.
624 if (partial_obj_size != 0) {
625 _region_data[split_region].set_partial_obj_size(0);
626 split_info.record(split_region, partial_obj_size, split_destination);
627 }
628
629 // Setup the continuation addresses.
630 *target_next = split_destination + partial_obj_size;
631 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
632
633 if (TraceParallelOldGCSummaryPhase) {
634 const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
635 gclog_or_tty->print_cr("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT
636 " pos=" SIZE_FORMAT,
637 split_type, source_next, split_region,
638 partial_obj_size);
639 gclog_or_tty->print_cr("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT
640 " tn=" PTR_FORMAT,
641 split_type, split_destination,
642 addr_to_region_idx(split_destination),
643 *target_next);
644
645 if (partial_obj_size != 0) {
646 HeapWord* const po_beg = split_info.destination();
647 HeapWord* const po_end = po_beg + split_info.partial_obj_size();
648 gclog_or_tty->print_cr("%s split: "
649 "po_beg=" PTR_FORMAT " " SIZE_FORMAT " "
650 "po_end=" PTR_FORMAT " " SIZE_FORMAT,
651 split_type,
652 po_beg, addr_to_region_idx(po_beg),
653 po_end, addr_to_region_idx(po_end));
654 }
655 }
656
657 return source_next;
658 }
659
660 bool ParallelCompactData::summarize(SplitInfo& split_info,
661 HeapWord* source_beg, HeapWord* source_end,
662 HeapWord** source_next,
663 HeapWord* target_beg, HeapWord* target_end,
664 HeapWord** target_next)
665 {
666 if (TraceParallelOldGCSummaryPhase) {
667 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
668 tty->print_cr("sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
669 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
670 source_beg, source_end, source_next_val,
671 target_beg, target_end, *target_next);
672 }
673
674 size_t cur_region = addr_to_region_idx(source_beg);
675 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
676
677 HeapWord *dest_addr = target_beg;
678 while (cur_region < end_region) {
679 // The destination must be set even if the region has no data.
680 _region_data[cur_region].set_destination(dest_addr);
681
682 size_t words = _region_data[cur_region].data_size();
683 if (words > 0) {
684 // If cur_region does not fit entirely into the target space, find a point
685 // at which the source space can be 'split' so that part is copied to the
686 // target space and the rest is copied elsewhere.
687 if (dest_addr + words > target_end) {
688 assert(source_next != NULL, "source_next is NULL when splitting");
689 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
690 target_end, target_next);
691 return false;
692 }
693
694 // Compute the destination_count for cur_region, and if necessary, update
695 // source_region for a destination region. The source_region field is
696 // updated if cur_region is the first (left-most) region to be copied to a
697 // destination region.
698 //
699 // The destination_count calculation is a bit subtle. A region that has
700 // data that compacts into itself does not count itself as a destination.
701 // This maintains the invariant that a zero count means the region is
702 // available and can be claimed and then filled.
703 uint destination_count = 0;
704 if (split_info.is_split(cur_region)) {
705 // The current region has been split: the partial object will be copied
706 // to one destination space and the remaining data will be copied to
707 // another destination space. Adjust the initial destination_count and,
708 // if necessary, set the source_region field if the partial object will
709 // cross a destination region boundary.
710 destination_count = split_info.destination_count();
711 if (destination_count == 2) {
712 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
713 _region_data[dest_idx].set_source_region(cur_region);
714 }
715 }
716
717 HeapWord* const last_addr = dest_addr + words - 1;
718 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
719 const size_t dest_region_2 = addr_to_region_idx(last_addr);
720
721 // Initially assume that the destination regions will be the same and
722 // adjust the value below if necessary. Under this assumption, if
723 // cur_region == dest_region_2, then cur_region will be compacted
724 // completely into itself.
725 destination_count += cur_region == dest_region_2 ? 0 : 1;
726 if (dest_region_1 != dest_region_2) {
727 // Destination regions differ; adjust destination_count.
728 destination_count += 1;
729 // Data from cur_region will be copied to the start of dest_region_2.
730 _region_data[dest_region_2].set_source_region(cur_region);
731 } else if (region_offset(dest_addr) == 0) {
732 // Data from cur_region will be copied to the start of the destination
733 // region.
734 _region_data[dest_region_1].set_source_region(cur_region);
735 }
736
737 _region_data[cur_region].set_destination_count(destination_count);
738 _region_data[cur_region].set_data_location(region_to_addr(cur_region));
739 dest_addr += words;
740 }
741
742 ++cur_region;
743 }
744
745 *target_next = dest_addr;
746 return true;
747 }
748
749 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) {
750 assert(addr != NULL, "Should detect NULL oop earlier");
751 assert(PSParallelCompact::gc_heap()->is_in(addr), "not in heap");
752 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked");
753
754 // Region covering the object.
755 RegionData* const region_ptr = addr_to_region_ptr(addr);
756 HeapWord* result = region_ptr->destination();
757
758 // If the entire Region is live, the new location is region->destination + the
759 // offset of the object within in the Region.
760
761 // Run some performance tests to determine if this special case pays off. It
762 // is worth it for pointers into the dense prefix. If the optimization to
763 // avoid pointer updates in regions that only point to the dense prefix is
764 // ever implemented, this should be revisited.
765 if (region_ptr->data_size() == RegionSize) {
766 result += region_offset(addr);
767 return result;
768 }
769
770 // Otherwise, the new location is region->destination + block offset + the
771 // number of live words in the Block that are (a) to the left of addr and (b)
772 // due to objects that start in the Block.
773
774 // Fill in the block table if necessary. This is unsynchronized, so multiple
775 // threads may fill the block table for a region (harmless, since it is
776 // idempotent).
777 if (!region_ptr->blocks_filled()) {
778 PSParallelCompact::fill_blocks(addr_to_region_idx(addr));
779 region_ptr->set_blocks_filled();
780 }
781
782 HeapWord* const search_start = block_align_down(addr);
783 const size_t block_offset = addr_to_block_ptr(addr)->offset();
784
785 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
786 const size_t live = bitmap->live_words_in_range(search_start, oop(addr));
787 result += block_offset + live;
788 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result));
789 return result;
790 }
791
792 #ifdef ASSERT
793 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
794 {
795 const size_t* const beg = (const size_t*)vspace->committed_low_addr();
796 const size_t* const end = (const size_t*)vspace->committed_high_addr();
797 for (const size_t* p = beg; p < end; ++p) {
798 assert(*p == 0, "not zero");
799 }
800 }
801
802 void ParallelCompactData::verify_clear()
803 {
804 verify_clear(_region_vspace);
805 verify_clear(_block_vspace);
806 }
807 #endif // #ifdef ASSERT
808
809 STWGCTimer PSParallelCompact::_gc_timer;
810 ParallelOldTracer PSParallelCompact::_gc_tracer;
811 elapsedTimer PSParallelCompact::_accumulated_time;
812 unsigned int PSParallelCompact::_total_invocations = 0;
813 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
814 jlong PSParallelCompact::_time_of_last_gc = 0;
815 CollectorCounters* PSParallelCompact::_counters = NULL;
816 ParMarkBitMap PSParallelCompact::_mark_bitmap;
817 ParallelCompactData PSParallelCompact::_summary_data;
818
819 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
820
821 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
822
823 void PSParallelCompact::KeepAliveClosure::do_oop(oop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
824 void PSParallelCompact::KeepAliveClosure::do_oop(narrowOop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
825
826 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_pointer_closure;
827 PSParallelCompact::AdjustKlassClosure PSParallelCompact::_adjust_klass_closure;
828
829 void PSParallelCompact::AdjustPointerClosure::do_oop(oop* p) { adjust_pointer(p); }
830 void PSParallelCompact::AdjustPointerClosure::do_oop(narrowOop* p) { adjust_pointer(p); }
831
832 void PSParallelCompact::FollowStackClosure::do_void() { _compaction_manager->follow_marking_stacks(); }
833
834 void PSParallelCompact::MarkAndPushClosure::do_oop(oop* p) {
835 mark_and_push(_compaction_manager, p);
836 }
837 void PSParallelCompact::MarkAndPushClosure::do_oop(narrowOop* p) { mark_and_push(_compaction_manager, p); }
838
839 void PSParallelCompact::FollowKlassClosure::do_klass(Klass* klass) {
840 klass->oops_do(_mark_and_push_closure);
841 }
842 void PSParallelCompact::AdjustKlassClosure::do_klass(Klass* klass) {
843 klass->oops_do(&PSParallelCompact::_adjust_pointer_closure);
844 }
845
846 void PSParallelCompact::post_initialize() {
847 ParallelScavengeHeap* heap = gc_heap();
848 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
849
850 MemRegion mr = heap->reserved_region();
851 _ref_processor =
852 new ReferenceProcessor(mr, // span
853 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
854 (int) ParallelGCThreads, // mt processing degree
855 true, // mt discovery
856 (int) ParallelGCThreads, // mt discovery degree
857 true, // atomic_discovery
858 &_is_alive_closure); // non-header is alive closure
859 _counters = new CollectorCounters("PSParallelCompact", 1);
860
861 // Initialize static fields in ParCompactionManager.
862 ParCompactionManager::initialize(mark_bitmap());
863 }
864
865 bool PSParallelCompact::initialize() {
866 ParallelScavengeHeap* heap = gc_heap();
867 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
868 MemRegion mr = heap->reserved_region();
869
870 // Was the old gen get allocated successfully?
871 if (!heap->old_gen()->is_allocated()) {
872 return false;
873 }
874
875 initialize_space_info();
876 initialize_dead_wood_limiter();
877
878 if (!_mark_bitmap.initialize(mr)) {
879 vm_shutdown_during_initialization(
880 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
881 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
882 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
883 return false;
884 }
885
886 if (!_summary_data.initialize(mr)) {
887 vm_shutdown_during_initialization(
888 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
889 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
890 _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
891 return false;
892 }
893
894 return true;
895 }
896
897 void PSParallelCompact::initialize_space_info()
898 {
899 memset(&_space_info, 0, sizeof(_space_info));
900
901 ParallelScavengeHeap* heap = gc_heap();
902 PSYoungGen* young_gen = heap->young_gen();
903
904 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
905 _space_info[eden_space_id].set_space(young_gen->eden_space());
906 _space_info[from_space_id].set_space(young_gen->from_space());
907 _space_info[to_space_id].set_space(young_gen->to_space());
908
909 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
910 }
911
912 void PSParallelCompact::initialize_dead_wood_limiter()
913 {
914 const size_t max = 100;
915 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
916 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
917 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
918 DEBUG_ONLY(_dwl_initialized = true;)
919 _dwl_adjustment = normal_distribution(1.0);
920 }
921
922 // Simple class for storing info about the heap at the start of GC, to be used
923 // after GC for comparison/printing.
924 class PreGCValues {
925 public:
926 PreGCValues() { }
927 PreGCValues(ParallelScavengeHeap* heap) { fill(heap); }
928
929 void fill(ParallelScavengeHeap* heap) {
930 _heap_used = heap->used();
931 _young_gen_used = heap->young_gen()->used_in_bytes();
932 _old_gen_used = heap->old_gen()->used_in_bytes();
933 _metadata_used = MetaspaceAux::used_bytes();
934 };
935
936 size_t heap_used() const { return _heap_used; }
937 size_t young_gen_used() const { return _young_gen_used; }
938 size_t old_gen_used() const { return _old_gen_used; }
939 size_t metadata_used() const { return _metadata_used; }
940
941 private:
942 size_t _heap_used;
943 size_t _young_gen_used;
944 size_t _old_gen_used;
945 size_t _metadata_used;
946 };
947
948 void
949 PSParallelCompact::clear_data_covering_space(SpaceId id)
950 {
951 // At this point, top is the value before GC, new_top() is the value that will
952 // be set at the end of GC. The marking bitmap is cleared to top; nothing
953 // should be marked above top. The summary data is cleared to the larger of
954 // top & new_top.
955 MutableSpace* const space = _space_info[id].space();
956 HeapWord* const bot = space->bottom();
957 HeapWord* const top = space->top();
958 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
959
960 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
961 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
962 _mark_bitmap.clear_range(beg_bit, end_bit);
963
964 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
965 const size_t end_region =
966 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
967 _summary_data.clear_range(beg_region, end_region);
968
969 // Clear the data used to 'split' regions.
970 SplitInfo& split_info = _space_info[id].split_info();
971 if (split_info.is_valid()) {
972 split_info.clear();
973 }
974 DEBUG_ONLY(split_info.verify_clear();)
975 }
976
977 void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values)
978 {
979 // Update the from & to space pointers in space_info, since they are swapped
980 // at each young gen gc. Do the update unconditionally (even though a
981 // promotion failure does not swap spaces) because an unknown number of minor
982 // collections will have swapped the spaces an unknown number of times.
983 GCTraceTime tm("pre compact", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
984 ParallelScavengeHeap* heap = gc_heap();
985 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
986 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
987
988 pre_gc_values->fill(heap);
989
990 DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
991 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
992
993 // Increment the invocation count
994 heap->increment_total_collections(true);
995
996 // We need to track unique mark sweep invocations as well.
997 _total_invocations++;
998
999 heap->print_heap_before_gc();
1000 heap->trace_heap_before_gc(&_gc_tracer);
1001
1002 // Fill in TLABs
1003 heap->accumulate_statistics_all_tlabs();
1004 heap->ensure_parsability(true); // retire TLABs
1005
1006 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
1007 HandleMark hm; // Discard invalid handles created during verification
1008 Universe::verify(" VerifyBeforeGC:");
1009 }
1010
1011 // Verify object start arrays
1012 if (VerifyObjectStartArray &&
1013 VerifyBeforeGC) {
1014 heap->old_gen()->verify_object_start_array();
1015 }
1016
1017 DEBUG_ONLY(mark_bitmap()->verify_clear();)
1018 DEBUG_ONLY(summary_data().verify_clear();)
1019
1020 // Have worker threads release resources the next time they run a task.
1021 gc_task_manager()->release_all_resources();
1022 }
1023
1024 void PSParallelCompact::post_compact()
1025 {
1026 GCTraceTime tm("post compact", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
1027
1028 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1029 // Clear the marking bitmap, summary data and split info.
1030 clear_data_covering_space(SpaceId(id));
1031 // Update top(). Must be done after clearing the bitmap and summary data.
1032 _space_info[id].publish_new_top();
1033 }
1034
1035 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1036 MutableSpace* const from_space = _space_info[from_space_id].space();
1037 MutableSpace* const to_space = _space_info[to_space_id].space();
1038
1039 ParallelScavengeHeap* heap = gc_heap();
1040 bool eden_empty = eden_space->is_empty();
1041 if (!eden_empty) {
1042 eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1043 heap->young_gen(), heap->old_gen());
1044 }
1045
1046 // Update heap occupancy information which is used as input to the soft ref
1047 // clearing policy at the next gc.
1048 Universe::update_heap_info_at_gc();
1049
1050 bool young_gen_empty = eden_empty && from_space->is_empty() &&
1051 to_space->is_empty();
1052
1053 BarrierSet* bs = heap->barrier_set();
1054 if (bs->is_a(BarrierSet::ModRef)) {
1055 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
1056 MemRegion old_mr = heap->old_gen()->reserved();
1057
1058 if (young_gen_empty) {
1059 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
1060 } else {
1061 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1062 }
1063 }
1064
1065 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1066 ClassLoaderDataGraph::purge();
1067 MetaspaceAux::verify_metrics();
1068
1069 CodeCache::gc_epilogue();
1070 JvmtiExport::gc_epilogue();
1071
1072 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1073
1074 ref_processor()->enqueue_discovered_references(NULL);
1075
1076 if (ZapUnusedHeapArea) {
1077 heap->gen_mangle_unused_area();
1078 }
1079
1080 // Update time of last GC
1081 reset_millis_since_last_gc();
1082 }
1083
1084 HeapWord*
1085 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1086 bool maximum_compaction)
1087 {
1088 const size_t region_size = ParallelCompactData::RegionSize;
1089 const ParallelCompactData& sd = summary_data();
1090
1091 const MutableSpace* const space = _space_info[id].space();
1092 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1093 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1094 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1095
1096 // Skip full regions at the beginning of the space--they are necessarily part
1097 // of the dense prefix.
1098 size_t full_count = 0;
1099 const RegionData* cp;
1100 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1101 ++full_count;
1102 }
1103
1104 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1105 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1106 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1107 if (maximum_compaction || cp == end_cp || interval_ended) {
1108 _maximum_compaction_gc_num = total_invocations();
1109 return sd.region_to_addr(cp);
1110 }
1111
1112 HeapWord* const new_top = _space_info[id].new_top();
1113 const size_t space_live = pointer_delta(new_top, space->bottom());
1114 const size_t space_used = space->used_in_words();
1115 const size_t space_capacity = space->capacity_in_words();
1116
1117 const double cur_density = double(space_live) / space_capacity;
1118 const double deadwood_density =
1119 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1120 const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1121
1122 if (TraceParallelOldGCDensePrefix) {
1123 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1124 cur_density, deadwood_density, deadwood_goal);
1125 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1126 "space_cap=" SIZE_FORMAT,
1127 space_live, space_used,
1128 space_capacity);
1129 }
1130
1131 // XXX - Use binary search?
1132 HeapWord* dense_prefix = sd.region_to_addr(cp);
1133 const RegionData* full_cp = cp;
1134 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1135 while (cp < end_cp) {
1136 HeapWord* region_destination = cp->destination();
1137 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1138 if (TraceParallelOldGCDensePrefix && Verbose) {
1139 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1140 "dp=" SIZE_FORMAT_W(8) " " "cdw=" SIZE_FORMAT_W(8),
1141 sd.region(cp), region_destination,
1142 dense_prefix, cur_deadwood);
1143 }
1144
1145 if (cur_deadwood >= deadwood_goal) {
1146 // Found the region that has the correct amount of deadwood to the left.
1147 // This typically occurs after crossing a fairly sparse set of regions, so
1148 // iterate backwards over those sparse regions, looking for the region
1149 // that has the lowest density of live objects 'to the right.'
1150 size_t space_to_left = sd.region(cp) * region_size;
1151 size_t live_to_left = space_to_left - cur_deadwood;
1152 size_t space_to_right = space_capacity - space_to_left;
1153 size_t live_to_right = space_live - live_to_left;
1154 double density_to_right = double(live_to_right) / space_to_right;
1155 while (cp > full_cp) {
1156 --cp;
1157 const size_t prev_region_live_to_right = live_to_right -
1158 cp->data_size();
1159 const size_t prev_region_space_to_right = space_to_right + region_size;
1160 double prev_region_density_to_right =
1161 double(prev_region_live_to_right) / prev_region_space_to_right;
1162 if (density_to_right <= prev_region_density_to_right) {
1163 return dense_prefix;
1164 }
1165 if (TraceParallelOldGCDensePrefix && Verbose) {
1166 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1167 "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1168 prev_region_density_to_right);
1169 }
1170 dense_prefix -= region_size;
1171 live_to_right = prev_region_live_to_right;
1172 space_to_right = prev_region_space_to_right;
1173 density_to_right = prev_region_density_to_right;
1174 }
1175 return dense_prefix;
1176 }
1177
1178 dense_prefix += region_size;
1179 ++cp;
1180 }
1181
1182 return dense_prefix;
1183 }
1184
1185 #ifndef PRODUCT
1186 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1187 const SpaceId id,
1188 const bool maximum_compaction,
1189 HeapWord* const addr)
1190 {
1191 const size_t region_idx = summary_data().addr_to_region_idx(addr);
1192 RegionData* const cp = summary_data().region(region_idx);
1193 const MutableSpace* const space = _space_info[id].space();
1194 HeapWord* const new_top = _space_info[id].new_top();
1195
1196 const size_t space_live = pointer_delta(new_top, space->bottom());
1197 const size_t dead_to_left = pointer_delta(addr, cp->destination());
1198 const size_t space_cap = space->capacity_in_words();
1199 const double dead_to_left_pct = double(dead_to_left) / space_cap;
1200 const size_t live_to_right = new_top - cp->destination();
1201 const size_t dead_to_right = space->top() - addr - live_to_right;
1202
1203 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1204 "spl=" SIZE_FORMAT " "
1205 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1206 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1207 " ratio=%10.8f",
1208 algorithm, addr, region_idx,
1209 space_live,
1210 dead_to_left, dead_to_left_pct,
1211 dead_to_right, live_to_right,
1212 double(dead_to_right) / live_to_right);
1213 }
1214 #endif // #ifndef PRODUCT
1215
1216 // Return a fraction indicating how much of the generation can be treated as
1217 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution
1218 // based on the density of live objects in the generation to determine a limit,
1219 // which is then adjusted so the return value is min_percent when the density is
1220 // 1.
1221 //
1222 // The following table shows some return values for a different values of the
1223 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1224 // min_percent is 1.
1225 //
1226 // fraction allowed as dead wood
1227 // -----------------------------------------------------------------
1228 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1229 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1230 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1231 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1232 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1233 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1234 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1235 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1236 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1237 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1238 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1239 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1240 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1241 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1242 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1243 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1244 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1245 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1246 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1247 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1248 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1249 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1250 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1251
1252 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1253 {
1254 assert(_dwl_initialized, "uninitialized");
1255
1256 // The raw limit is the value of the normal distribution at x = density.
1257 const double raw_limit = normal_distribution(density);
1258
1259 // Adjust the raw limit so it becomes the minimum when the density is 1.
1260 //
1261 // First subtract the adjustment value (which is simply the precomputed value
1262 // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1263 // Then add the minimum value, so the minimum is returned when the density is
1264 // 1. Finally, prevent negative values, which occur when the mean is not 0.5.
1265 const double min = double(min_percent) / 100.0;
1266 const double limit = raw_limit - _dwl_adjustment + min;
1267 return MAX2(limit, 0.0);
1268 }
1269
1270 ParallelCompactData::RegionData*
1271 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1272 const RegionData* end)
1273 {
1274 const size_t region_size = ParallelCompactData::RegionSize;
1275 ParallelCompactData& sd = summary_data();
1276 size_t left = sd.region(beg);
1277 size_t right = end > beg ? sd.region(end) - 1 : left;
1278
1279 // Binary search.
1280 while (left < right) {
1281 // Equivalent to (left + right) / 2, but does not overflow.
1282 const size_t middle = left + (right - left) / 2;
1283 RegionData* const middle_ptr = sd.region(middle);
1284 HeapWord* const dest = middle_ptr->destination();
1285 HeapWord* const addr = sd.region_to_addr(middle);
1286 assert(dest != NULL, "sanity");
1287 assert(dest <= addr, "must move left");
1288
1289 if (middle > left && dest < addr) {
1290 right = middle - 1;
1291 } else if (middle < right && middle_ptr->data_size() == region_size) {
1292 left = middle + 1;
1293 } else {
1294 return middle_ptr;
1295 }
1296 }
1297 return sd.region(left);
1298 }
1299
1300 ParallelCompactData::RegionData*
1301 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1302 const RegionData* end,
1303 size_t dead_words)
1304 {
1305 ParallelCompactData& sd = summary_data();
1306 size_t left = sd.region(beg);
1307 size_t right = end > beg ? sd.region(end) - 1 : left;
1308
1309 // Binary search.
1310 while (left < right) {
1311 // Equivalent to (left + right) / 2, but does not overflow.
1312 const size_t middle = left + (right - left) / 2;
1313 RegionData* const middle_ptr = sd.region(middle);
1314 HeapWord* const dest = middle_ptr->destination();
1315 HeapWord* const addr = sd.region_to_addr(middle);
1316 assert(dest != NULL, "sanity");
1317 assert(dest <= addr, "must move left");
1318
1319 const size_t dead_to_left = pointer_delta(addr, dest);
1320 if (middle > left && dead_to_left > dead_words) {
1321 right = middle - 1;
1322 } else if (middle < right && dead_to_left < dead_words) {
1323 left = middle + 1;
1324 } else {
1325 return middle_ptr;
1326 }
1327 }
1328 return sd.region(left);
1329 }
1330
1331 // The result is valid during the summary phase, after the initial summarization
1332 // of each space into itself, and before final summarization.
1333 inline double
1334 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1335 HeapWord* const bottom,
1336 HeapWord* const top,
1337 HeapWord* const new_top)
1338 {
1339 ParallelCompactData& sd = summary_data();
1340
1341 assert(cp != NULL, "sanity");
1342 assert(bottom != NULL, "sanity");
1343 assert(top != NULL, "sanity");
1344 assert(new_top != NULL, "sanity");
1345 assert(top >= new_top, "summary data problem?");
1346 assert(new_top > bottom, "space is empty; should not be here");
1347 assert(new_top >= cp->destination(), "sanity");
1348 assert(top >= sd.region_to_addr(cp), "sanity");
1349
1350 HeapWord* const destination = cp->destination();
1351 const size_t dense_prefix_live = pointer_delta(destination, bottom);
1352 const size_t compacted_region_live = pointer_delta(new_top, destination);
1353 const size_t compacted_region_used = pointer_delta(top,
1354 sd.region_to_addr(cp));
1355 const size_t reclaimable = compacted_region_used - compacted_region_live;
1356
1357 const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1358 return double(reclaimable) / divisor;
1359 }
1360
1361 // Return the address of the end of the dense prefix, a.k.a. the start of the
1362 // compacted region. The address is always on a region boundary.
1363 //
1364 // Completely full regions at the left are skipped, since no compaction can
1365 // occur in those regions. Then the maximum amount of dead wood to allow is
1366 // computed, based on the density (amount live / capacity) of the generation;
1367 // the region with approximately that amount of dead space to the left is
1368 // identified as the limit region. Regions between the last completely full
1369 // region and the limit region are scanned and the one that has the best
1370 // (maximum) reclaimed_ratio() is selected.
1371 HeapWord*
1372 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1373 bool maximum_compaction)
1374 {
1375 if (ParallelOldGCSplitALot) {
1376 if (_space_info[id].dense_prefix() != _space_info[id].space()->bottom()) {
1377 // The value was chosen to provoke splitting a young gen space; use it.
1378 return _space_info[id].dense_prefix();
1379 }
1380 }
1381
1382 const size_t region_size = ParallelCompactData::RegionSize;
1383 const ParallelCompactData& sd = summary_data();
1384
1385 const MutableSpace* const space = _space_info[id].space();
1386 HeapWord* const top = space->top();
1387 HeapWord* const top_aligned_up = sd.region_align_up(top);
1388 HeapWord* const new_top = _space_info[id].new_top();
1389 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1390 HeapWord* const bottom = space->bottom();
1391 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1392 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1393 const RegionData* const new_top_cp =
1394 sd.addr_to_region_ptr(new_top_aligned_up);
1395
1396 // Skip full regions at the beginning of the space--they are necessarily part
1397 // of the dense prefix.
1398 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1399 assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1400 space->is_empty(), "no dead space allowed to the left");
1401 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1402 "region must have dead space");
1403
1404 // The gc number is saved whenever a maximum compaction is done, and used to
1405 // determine when the maximum compaction interval has expired. This avoids
1406 // successive max compactions for different reasons.
1407 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1408 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1409 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1410 total_invocations() == HeapFirstMaximumCompactionCount;
1411 if (maximum_compaction || full_cp == top_cp || interval_ended) {
1412 _maximum_compaction_gc_num = total_invocations();
1413 return sd.region_to_addr(full_cp);
1414 }
1415
1416 const size_t space_live = pointer_delta(new_top, bottom);
1417 const size_t space_used = space->used_in_words();
1418 const size_t space_capacity = space->capacity_in_words();
1419
1420 const double density = double(space_live) / double(space_capacity);
1421 const size_t min_percent_free = MarkSweepDeadRatio;
1422 const double limiter = dead_wood_limiter(density, min_percent_free);
1423 const size_t dead_wood_max = space_used - space_live;
1424 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1425 dead_wood_max);
1426
1427 if (TraceParallelOldGCDensePrefix) {
1428 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1429 "space_cap=" SIZE_FORMAT,
1430 space_live, space_used,
1431 space_capacity);
1432 tty->print_cr("dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f "
1433 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1434 density, min_percent_free, limiter,
1435 dead_wood_max, dead_wood_limit);
1436 }
1437
1438 // Locate the region with the desired amount of dead space to the left.
1439 const RegionData* const limit_cp =
1440 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1441
1442 // Scan from the first region with dead space to the limit region and find the
1443 // one with the best (largest) reclaimed ratio.
1444 double best_ratio = 0.0;
1445 const RegionData* best_cp = full_cp;
1446 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1447 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1448 if (tmp_ratio > best_ratio) {
1449 best_cp = cp;
1450 best_ratio = tmp_ratio;
1451 }
1452 }
1453
1454 #if 0
1455 // Something to consider: if the region with the best ratio is 'close to' the
1456 // first region w/free space, choose the first region with free space
1457 // ("first-free"). The first-free region is usually near the start of the
1458 // heap, which means we are copying most of the heap already, so copy a bit
1459 // more to get complete compaction.
1460 if (pointer_delta(best_cp, full_cp, sizeof(RegionData)) < 4) {
1461 _maximum_compaction_gc_num = total_invocations();
1462 best_cp = full_cp;
1463 }
1464 #endif // #if 0
1465
1466 return sd.region_to_addr(best_cp);
1467 }
1468
1469 #ifndef PRODUCT
1470 void
1471 PSParallelCompact::fill_with_live_objects(SpaceId id, HeapWord* const start,
1472 size_t words)
1473 {
1474 if (TraceParallelOldGCSummaryPhase) {
1475 tty->print_cr("fill_with_live_objects [" PTR_FORMAT " " PTR_FORMAT ") "
1476 SIZE_FORMAT, start, start + words, words);
1477 }
1478
1479 ObjectStartArray* const start_array = _space_info[id].start_array();
1480 CollectedHeap::fill_with_objects(start, words);
1481 for (HeapWord* p = start; p < start + words; p += oop(p)->size()) {
1482 _mark_bitmap.mark_obj(p, words);
1483 _summary_data.add_obj(p, words);
1484 start_array->allocate_block(p);
1485 }
1486 }
1487
1488 void
1489 PSParallelCompact::summarize_new_objects(SpaceId id, HeapWord* start)
1490 {
1491 ParallelCompactData& sd = summary_data();
1492 MutableSpace* space = _space_info[id].space();
1493
1494 // Find the source and destination start addresses.
1495 HeapWord* const src_addr = sd.region_align_down(start);
1496 HeapWord* dst_addr;
1497 if (src_addr < start) {
1498 dst_addr = sd.addr_to_region_ptr(src_addr)->destination();
1499 } else if (src_addr > space->bottom()) {
1500 // The start (the original top() value) is aligned to a region boundary so
1501 // the associated region does not have a destination. Compute the
1502 // destination from the previous region.
1503 RegionData* const cp = sd.addr_to_region_ptr(src_addr) - 1;
1504 dst_addr = cp->destination() + cp->data_size();
1505 } else {
1506 // Filling the entire space.
1507 dst_addr = space->bottom();
1508 }
1509 assert(dst_addr != NULL, "sanity");
1510
1511 // Update the summary data.
1512 bool result = _summary_data.summarize(_space_info[id].split_info(),
1513 src_addr, space->top(), NULL,
1514 dst_addr, space->end(),
1515 _space_info[id].new_top_addr());
1516 assert(result, "should not fail: bad filler object size");
1517 }
1518
1519 void
1520 PSParallelCompact::provoke_split_fill_survivor(SpaceId id)
1521 {
1522 if (total_invocations() % (ParallelOldGCSplitInterval * 3) != 0) {
1523 return;
1524 }
1525
1526 MutableSpace* const space = _space_info[id].space();
1527 if (space->is_empty()) {
1528 HeapWord* b = space->bottom();
1529 HeapWord* t = b + space->capacity_in_words() / 2;
1530 space->set_top(t);
1531 if (ZapUnusedHeapArea) {
1532 space->set_top_for_allocations();
1533 }
1534
1535 size_t min_size = CollectedHeap::min_fill_size();
1536 size_t obj_len = min_size;
1537 while (b + obj_len <= t) {
1538 CollectedHeap::fill_with_object(b, obj_len);
1539 mark_bitmap()->mark_obj(b, obj_len);
1540 summary_data().add_obj(b, obj_len);
1541 b += obj_len;
1542 obj_len = (obj_len & (min_size*3)) + min_size; // 8 16 24 32 8 16 24 32 ...
1543 }
1544 if (b < t) {
1545 // The loop didn't completely fill to t (top); adjust top downward.
1546 space->set_top(b);
1547 if (ZapUnusedHeapArea) {
1548 space->set_top_for_allocations();
1549 }
1550 }
1551
1552 HeapWord** nta = _space_info[id].new_top_addr();
1553 bool result = summary_data().summarize(_space_info[id].split_info(),
1554 space->bottom(), space->top(), NULL,
1555 space->bottom(), space->end(), nta);
1556 assert(result, "space must fit into itself");
1557 }
1558 }
1559
1560 void
1561 PSParallelCompact::provoke_split(bool & max_compaction)
1562 {
1563 if (total_invocations() % ParallelOldGCSplitInterval != 0) {
1564 return;
1565 }
1566
1567 const size_t region_size = ParallelCompactData::RegionSize;
1568 ParallelCompactData& sd = summary_data();
1569
1570 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1571 MutableSpace* const from_space = _space_info[from_space_id].space();
1572 const size_t eden_live = pointer_delta(eden_space->top(),
1573 _space_info[eden_space_id].new_top());
1574 const size_t from_live = pointer_delta(from_space->top(),
1575 _space_info[from_space_id].new_top());
1576
1577 const size_t min_fill_size = CollectedHeap::min_fill_size();
1578 const size_t eden_free = pointer_delta(eden_space->end(), eden_space->top());
1579 const size_t eden_fillable = eden_free >= min_fill_size ? eden_free : 0;
1580 const size_t from_free = pointer_delta(from_space->end(), from_space->top());
1581 const size_t from_fillable = from_free >= min_fill_size ? from_free : 0;
1582
1583 // Choose the space to split; need at least 2 regions live (or fillable).
1584 SpaceId id;
1585 MutableSpace* space;
1586 size_t live_words;
1587 size_t fill_words;
1588 if (eden_live + eden_fillable >= region_size * 2) {
1589 id = eden_space_id;
1590 space = eden_space;
1591 live_words = eden_live;
1592 fill_words = eden_fillable;
1593 } else if (from_live + from_fillable >= region_size * 2) {
1594 id = from_space_id;
1595 space = from_space;
1596 live_words = from_live;
1597 fill_words = from_fillable;
1598 } else {
1599 return; // Give up.
1600 }
1601 assert(fill_words == 0 || fill_words >= min_fill_size, "sanity");
1602
1603 if (live_words < region_size * 2) {
1604 // Fill from top() to end() w/live objects of mixed sizes.
1605 HeapWord* const fill_start = space->top();
1606 live_words += fill_words;
1607
1608 space->set_top(fill_start + fill_words);
1609 if (ZapUnusedHeapArea) {
1610 space->set_top_for_allocations();
1611 }
1612
1613 HeapWord* cur_addr = fill_start;
1614 while (fill_words > 0) {
1615 const size_t r = (size_t)os::random() % (region_size / 2) + min_fill_size;
1616 size_t cur_size = MIN2(align_object_size_(r), fill_words);
1617 if (fill_words - cur_size < min_fill_size) {
1618 cur_size = fill_words; // Avoid leaving a fragment too small to fill.
1619 }
1620
1621 CollectedHeap::fill_with_object(cur_addr, cur_size);
1622 mark_bitmap()->mark_obj(cur_addr, cur_size);
1623 sd.add_obj(cur_addr, cur_size);
1624
1625 cur_addr += cur_size;
1626 fill_words -= cur_size;
1627 }
1628
1629 summarize_new_objects(id, fill_start);
1630 }
1631
1632 max_compaction = false;
1633
1634 // Manipulate the old gen so that it has room for about half of the live data
1635 // in the target young gen space (live_words / 2).
1636 id = old_space_id;
1637 space = _space_info[id].space();
1638 const size_t free_at_end = space->free_in_words();
1639 const size_t free_target = align_object_size(live_words / 2);
1640 const size_t dead = pointer_delta(space->top(), _space_info[id].new_top());
1641
1642 if (free_at_end >= free_target + min_fill_size) {
1643 // Fill space above top() and set the dense prefix so everything survives.
1644 HeapWord* const fill_start = space->top();
1645 const size_t fill_size = free_at_end - free_target;
1646 space->set_top(space->top() + fill_size);
1647 if (ZapUnusedHeapArea) {
1648 space->set_top_for_allocations();
1649 }
1650 fill_with_live_objects(id, fill_start, fill_size);
1651 summarize_new_objects(id, fill_start);
1652 _space_info[id].set_dense_prefix(sd.region_align_down(space->top()));
1653 } else if (dead + free_at_end > free_target) {
1654 // Find a dense prefix that makes the right amount of space available.
1655 HeapWord* cur = sd.region_align_down(space->top());
1656 HeapWord* cur_destination = sd.addr_to_region_ptr(cur)->destination();
1657 size_t dead_to_right = pointer_delta(space->end(), cur_destination);
1658 while (dead_to_right < free_target) {
1659 cur -= region_size;
1660 cur_destination = sd.addr_to_region_ptr(cur)->destination();
1661 dead_to_right = pointer_delta(space->end(), cur_destination);
1662 }
1663 _space_info[id].set_dense_prefix(cur);
1664 }
1665 }
1666 #endif // #ifndef PRODUCT
1667
1668 void PSParallelCompact::summarize_spaces_quick()
1669 {
1670 for (unsigned int i = 0; i < last_space_id; ++i) {
1671 const MutableSpace* space = _space_info[i].space();
1672 HeapWord** nta = _space_info[i].new_top_addr();
1673 bool result = _summary_data.summarize(_space_info[i].split_info(),
1674 space->bottom(), space->top(), NULL,
1675 space->bottom(), space->end(), nta);
1676 assert(result, "space must fit into itself");
1677 _space_info[i].set_dense_prefix(space->bottom());
1678 }
1679
1680 #ifndef PRODUCT
1681 if (ParallelOldGCSplitALot) {
1682 provoke_split_fill_survivor(to_space_id);
1683 }
1684 #endif // #ifndef PRODUCT
1685 }
1686
1687 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1688 {
1689 HeapWord* const dense_prefix_end = dense_prefix(id);
1690 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1691 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1692 if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1693 // Only enough dead space is filled so that any remaining dead space to the
1694 // left is larger than the minimum filler object. (The remainder is filled
1695 // during the copy/update phase.)
1696 //
1697 // The size of the dead space to the right of the boundary is not a
1698 // concern, since compaction will be able to use whatever space is
1699 // available.
1700 //
1701 // Here '||' is the boundary, 'x' represents a don't care bit and a box
1702 // surrounds the space to be filled with an object.
1703 //
1704 // In the 32-bit VM, each bit represents two 32-bit words:
1705 // +---+
1706 // a) beg_bits: ... x x x | 0 | || 0 x x ...
1707 // end_bits: ... x x x | 0 | || 0 x x ...
1708 // +---+
1709 //
1710 // In the 64-bit VM, each bit represents one 64-bit word:
1711 // +------------+
1712 // b) beg_bits: ... x x x | 0 || 0 | x x ...
1713 // end_bits: ... x x 1 | 0 || 0 | x x ...
1714 // +------------+
1715 // +-------+
1716 // c) beg_bits: ... x x | 0 0 | || 0 x x ...
1717 // end_bits: ... x 1 | 0 0 | || 0 x x ...
1718 // +-------+
1719 // +-----------+
1720 // d) beg_bits: ... x | 0 0 0 | || 0 x x ...
1721 // end_bits: ... 1 | 0 0 0 | || 0 x x ...
1722 // +-----------+
1723 // +-------+
1724 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ...
1725 // end_bits: ... 0 0 | 0 0 | || 0 x x ...
1726 // +-------+
1727
1728 // Initially assume case a, c or e will apply.
1729 size_t obj_len = CollectedHeap::min_fill_size();
1730 HeapWord* obj_beg = dense_prefix_end - obj_len;
1731
1732 #ifdef _LP64
1733 if (MinObjAlignment > 1) { // object alignment > heap word size
1734 // Cases a, c or e.
1735 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1736 // Case b above.
1737 obj_beg = dense_prefix_end - 1;
1738 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1739 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1740 // Case d above.
1741 obj_beg = dense_prefix_end - 3;
1742 obj_len = 3;
1743 }
1744 #endif // #ifdef _LP64
1745
1746 CollectedHeap::fill_with_object(obj_beg, obj_len);
1747 _mark_bitmap.mark_obj(obj_beg, obj_len);
1748 _summary_data.add_obj(obj_beg, obj_len);
1749 assert(start_array(id) != NULL, "sanity");
1750 start_array(id)->allocate_block(obj_beg);
1751 }
1752 }
1753
1754 void
1755 PSParallelCompact::clear_source_region(HeapWord* beg_addr, HeapWord* end_addr)
1756 {
1757 RegionData* const beg_ptr = _summary_data.addr_to_region_ptr(beg_addr);
1758 HeapWord* const end_aligned_up = _summary_data.region_align_up(end_addr);
1759 RegionData* const end_ptr = _summary_data.addr_to_region_ptr(end_aligned_up);
1760 for (RegionData* cur = beg_ptr; cur < end_ptr; ++cur) {
1761 cur->set_source_region(0);
1762 }
1763 }
1764
1765 void
1766 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1767 {
1768 assert(id < last_space_id, "id out of range");
1769 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom() ||
1770 ParallelOldGCSplitALot && id == old_space_id,
1771 "should have been reset in summarize_spaces_quick()");
1772
1773 const MutableSpace* space = _space_info[id].space();
1774 if (_space_info[id].new_top() != space->bottom()) {
1775 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1776 _space_info[id].set_dense_prefix(dense_prefix_end);
1777
1778 #ifndef PRODUCT
1779 if (TraceParallelOldGCDensePrefix) {
1780 print_dense_prefix_stats("ratio", id, maximum_compaction,
1781 dense_prefix_end);
1782 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1783 print_dense_prefix_stats("density", id, maximum_compaction, addr);
1784 }
1785 #endif // #ifndef PRODUCT
1786
1787 // Recompute the summary data, taking into account the dense prefix. If
1788 // every last byte will be reclaimed, then the existing summary data which
1789 // compacts everything can be left in place.
1790 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1791 // If dead space crosses the dense prefix boundary, it is (at least
1792 // partially) filled with a dummy object, marked live and added to the
1793 // summary data. This simplifies the copy/update phase and must be done
1794 // before the final locations of objects are determined, to prevent
1795 // leaving a fragment of dead space that is too small to fill.
1796 fill_dense_prefix_end(id);
1797
1798 // Compute the destination of each Region, and thus each object.
1799 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1800 _summary_data.summarize(_space_info[id].split_info(),
1801 dense_prefix_end, space->top(), NULL,
1802 dense_prefix_end, space->end(),
1803 _space_info[id].new_top_addr());
1804 }
1805 }
1806
1807 if (TraceParallelOldGCSummaryPhase) {
1808 const size_t region_size = ParallelCompactData::RegionSize;
1809 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1810 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1811 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1812 HeapWord* const new_top = _space_info[id].new_top();
1813 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1814 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1815 tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1816 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1817 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1818 id, space->capacity_in_words(), dense_prefix_end,
1819 dp_region, dp_words / region_size,
1820 cr_words / region_size, new_top);
1821 }
1822 }
1823
1824 #ifndef PRODUCT
1825 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1826 HeapWord* dst_beg, HeapWord* dst_end,
1827 SpaceId src_space_id,
1828 HeapWord* src_beg, HeapWord* src_end)
1829 {
1830 if (TraceParallelOldGCSummaryPhase) {
1831 tty->print_cr("summarizing %d [%s] into %d [%s]: "
1832 "src=" PTR_FORMAT "-" PTR_FORMAT " "
1833 SIZE_FORMAT "-" SIZE_FORMAT " "
1834 "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1835 SIZE_FORMAT "-" SIZE_FORMAT,
1836 src_space_id, space_names[src_space_id],
1837 dst_space_id, space_names[dst_space_id],
1838 src_beg, src_end,
1839 _summary_data.addr_to_region_idx(src_beg),
1840 _summary_data.addr_to_region_idx(src_end),
1841 dst_beg, dst_end,
1842 _summary_data.addr_to_region_idx(dst_beg),
1843 _summary_data.addr_to_region_idx(dst_end));
1844 }
1845 }
1846 #endif // #ifndef PRODUCT
1847
1848 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1849 bool maximum_compaction)
1850 {
1851 GCTraceTime tm("summary phase", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
1852 // trace("2");
1853
1854 #ifdef ASSERT
1855 if (TraceParallelOldGCMarkingPhase) {
1856 tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1857 "add_obj_bytes=" SIZE_FORMAT,
1858 add_obj_count, add_obj_size * HeapWordSize);
1859 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1860 "mark_bitmap_bytes=" SIZE_FORMAT,
1861 mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1862 }
1863 #endif // #ifdef ASSERT
1864
1865 // Quick summarization of each space into itself, to see how much is live.
1866 summarize_spaces_quick();
1867
1868 if (TraceParallelOldGCSummaryPhase) {
1869 tty->print_cr("summary_phase: after summarizing each space to self");
1870 Universe::print();
1871 NOT_PRODUCT(print_region_ranges());
1872 if (Verbose) {
1873 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1874 }
1875 }
1876
1877 // The amount of live data that will end up in old space (assuming it fits).
1878 size_t old_space_total_live = 0;
1879 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1880 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1881 _space_info[id].space()->bottom());
1882 }
1883
1884 MutableSpace* const old_space = _space_info[old_space_id].space();
1885 const size_t old_capacity = old_space->capacity_in_words();
1886 if (old_space_total_live > old_capacity) {
1887 // XXX - should also try to expand
1888 maximum_compaction = true;
1889 }
1890 #ifndef PRODUCT
1891 if (ParallelOldGCSplitALot && old_space_total_live < old_capacity) {
1892 provoke_split(maximum_compaction);
1893 }
1894 #endif // #ifndef PRODUCT
1895
1896 // Old generations.
1897 summarize_space(old_space_id, maximum_compaction);
1898
1899 // Summarize the remaining spaces in the young gen. The initial target space
1900 // is the old gen. If a space does not fit entirely into the target, then the
1901 // remainder is compacted into the space itself and that space becomes the new
1902 // target.
1903 SpaceId dst_space_id = old_space_id;
1904 HeapWord* dst_space_end = old_space->end();
1905 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1906 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1907 const MutableSpace* space = _space_info[id].space();
1908 const size_t live = pointer_delta(_space_info[id].new_top(),
1909 space->bottom());
1910 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1911
1912 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1913 SpaceId(id), space->bottom(), space->top());)
1914 if (live > 0 && live <= available) {
1915 // All the live data will fit.
1916 bool done = _summary_data.summarize(_space_info[id].split_info(),
1917 space->bottom(), space->top(),
1918 NULL,
1919 *new_top_addr, dst_space_end,
1920 new_top_addr);
1921 assert(done, "space must fit into old gen");
1922
1923 // Reset the new_top value for the space.
1924 _space_info[id].set_new_top(space->bottom());
1925 } else if (live > 0) {
1926 // Attempt to fit part of the source space into the target space.
1927 HeapWord* next_src_addr = NULL;
1928 bool done = _summary_data.summarize(_space_info[id].split_info(),
1929 space->bottom(), space->top(),
1930 &next_src_addr,
1931 *new_top_addr, dst_space_end,
1932 new_top_addr);
1933 assert(!done, "space should not fit into old gen");
1934 assert(next_src_addr != NULL, "sanity");
1935
1936 // The source space becomes the new target, so the remainder is compacted
1937 // within the space itself.
1938 dst_space_id = SpaceId(id);
1939 dst_space_end = space->end();
1940 new_top_addr = _space_info[id].new_top_addr();
1941 NOT_PRODUCT(summary_phase_msg(dst_space_id,
1942 space->bottom(), dst_space_end,
1943 SpaceId(id), next_src_addr, space->top());)
1944 done = _summary_data.summarize(_space_info[id].split_info(),
1945 next_src_addr, space->top(),
1946 NULL,
1947 space->bottom(), dst_space_end,
1948 new_top_addr);
1949 assert(done, "space must fit when compacted into itself");
1950 assert(*new_top_addr <= space->top(), "usage should not grow");
1951 }
1952 }
1953
1954 if (TraceParallelOldGCSummaryPhase) {
1955 tty->print_cr("summary_phase: after final summarization");
1956 Universe::print();
1957 NOT_PRODUCT(print_region_ranges());
1958 if (Verbose) {
1959 NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info));
1960 }
1961 }
1962 }
1963
1964 // This method should contain all heap-specific policy for invoking a full
1965 // collection. invoke_no_policy() will only attempt to compact the heap; it
1966 // will do nothing further. If we need to bail out for policy reasons, scavenge
1967 // before full gc, or any other specialized behavior, it needs to be added here.
1968 //
1969 // Note that this method should only be called from the vm_thread while at a
1970 // safepoint.
1971 //
1972 // Note that the all_soft_refs_clear flag in the collector policy
1973 // may be true because this method can be called without intervening
1974 // activity. For example when the heap space is tight and full measure
1975 // are being taken to free space.
1976 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1977 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1978 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1979 "should be in vm thread");
1980
1981 ParallelScavengeHeap* heap = gc_heap();
1982 GCCause::Cause gc_cause = heap->gc_cause();
1983 assert(!heap->is_gc_active(), "not reentrant");
1984
1985 PSAdaptiveSizePolicy* policy = heap->size_policy();
1986 IsGCActiveMark mark;
1987
1988 if (ScavengeBeforeFullGC) {
1989 PSScavenge::invoke_no_policy();
1990 }
1991
1992 const bool clear_all_soft_refs =
1993 heap->collector_policy()->should_clear_all_soft_refs();
1994
1995 PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1996 maximum_heap_compaction);
1997 }
1998
1999 // This method contains no policy. You should probably
2000 // be calling invoke() instead.
2001 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
2002 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
2003 assert(ref_processor() != NULL, "Sanity");
2004
2005 if (GC_locker::check_active_before_gc()) {
2006 return false;
2007 }
2008
2009 ParallelScavengeHeap* heap = gc_heap();
2010
2011 _gc_timer.register_gc_start();
2012 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
2013
2014 TimeStamp marking_start;
2015 TimeStamp compaction_start;
2016 TimeStamp collection_exit;
2017
2018 GCCause::Cause gc_cause = heap->gc_cause();
2019 PSYoungGen* young_gen = heap->young_gen();
2020 PSOldGen* old_gen = heap->old_gen();
2021 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
2022
2023 // The scope of casr should end after code that can change
2024 // CollectorPolicy::_should_clear_all_soft_refs.
2025 ClearedAllSoftRefs casr(maximum_heap_compaction,
2026 heap->collector_policy());
2027
2028 if (ZapUnusedHeapArea) {
2029 // Save information needed to minimize mangling
2030 heap->record_gen_tops_before_GC();
2031 }
2032
2033 heap->pre_full_gc_dump(&_gc_timer);
2034
2035 _print_phases = PrintGCDetails && PrintParallelOldGCPhaseTimes;
2036
2037 // Make sure data structures are sane, make the heap parsable, and do other
2038 // miscellaneous bookkeeping.
2039 PreGCValues pre_gc_values;
2040 pre_compact(&pre_gc_values);
2041
2042 // Get the compaction manager reserved for the VM thread.
2043 ParCompactionManager* const vmthread_cm =
2044 ParCompactionManager::manager_array(gc_task_manager()->workers());
2045
2046 // Place after pre_compact() where the number of invocations is incremented.
2047 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
2048
2049 {
2050 ResourceMark rm;
2051 HandleMark hm;
2052
2053 // Set the number of GC threads to be used in this collection
2054 gc_task_manager()->set_active_gang();
2055 gc_task_manager()->task_idle_workers();
2056 heap->set_par_threads(gc_task_manager()->active_workers());
2057
2058 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2059 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2060 GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL, _gc_tracer.gc_id());
2061 TraceCollectorStats tcs(counters());
2062 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
2063
2064 if (TraceOldGenTime) accumulated_time()->start();
2065
2066 // Let the size policy know we're starting
2067 size_policy->major_collection_begin();
2068
2069 CodeCache::gc_prologue();
2070
2071 COMPILER2_PRESENT(DerivedPointerTable::clear());
2072
2073 ref_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
2074 ref_processor()->setup_policy(maximum_heap_compaction);
2075
2076 bool marked_for_unloading = false;
2077
2078 marking_start.update();
2079 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer);
2080
2081 bool max_on_system_gc = UseMaximumCompactionOnSystemGC
2082 && gc_cause == GCCause::_java_lang_system_gc;
2083 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
2084
2085 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
2086 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
2087
2088 // adjust_roots() updates Universe::_intArrayKlassObj which is
2089 // needed by the compaction for filling holes in the dense prefix.
2090 adjust_roots();
2091
2092 compaction_start.update();
2093 compact();
2094
2095 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
2096 // done before resizing.
2097 post_compact();
2098
2099 // Let the size policy know we're done
2100 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
2101
2102 if (UseAdaptiveSizePolicy) {
2103 if (PrintAdaptiveSizePolicy) {
2104 gclog_or_tty->print("AdaptiveSizeStart: ");
2105 gclog_or_tty->stamp();
2106 gclog_or_tty->print_cr(" collection: %d ",
2107 heap->total_collections());
2108 if (Verbose) {
2109 gclog_or_tty->print("old_gen_capacity: " SIZE_FORMAT
2110 " young_gen_capacity: " SIZE_FORMAT,
2111 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
2112 }
2113 }
2114
2115 // Don't check if the size_policy is ready here. Let
2116 // the size_policy check that internally.
2117 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
2118 ((gc_cause != GCCause::_java_lang_system_gc) ||
2119 UseAdaptiveSizePolicyWithSystemGC)) {
2120 // Swap the survivor spaces if from_space is empty. The
2121 // resize_young_gen() called below is normally used after
2122 // a successful young GC and swapping of survivor spaces;
2123 // otherwise, it will fail to resize the young gen with
2124 // the current implementation.
2125 if (young_gen->from_space()->is_empty()) {
2126 young_gen->from_space()->clear(SpaceDecorator::Mangle);
2127 young_gen->swap_spaces();
2128 }
2129
2130 // Calculate optimal free space amounts
2131 assert(young_gen->max_size() >
2132 young_gen->from_space()->capacity_in_bytes() +
2133 young_gen->to_space()->capacity_in_bytes(),
2134 "Sizes of space in young gen are out-of-bounds");
2135
2136 size_t young_live = young_gen->used_in_bytes();
2137 size_t eden_live = young_gen->eden_space()->used_in_bytes();
2138 size_t old_live = old_gen->used_in_bytes();
2139 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
2140 size_t max_old_gen_size = old_gen->max_gen_size();
2141 size_t max_eden_size = young_gen->max_size() -
2142 young_gen->from_space()->capacity_in_bytes() -
2143 young_gen->to_space()->capacity_in_bytes();
2144
2145 // Used for diagnostics
2146 size_policy->clear_generation_free_space_flags();
2147
2148 size_policy->compute_generations_free_space(young_live,
2149 eden_live,
2150 old_live,
2151 cur_eden,
2152 max_old_gen_size,
2153 max_eden_size,
2154 true /* full gc*/);
2155
2156 size_policy->check_gc_overhead_limit(young_live,
2157 eden_live,
2158 max_old_gen_size,
2159 max_eden_size,
2160 true /* full gc*/,
2161 gc_cause,
2162 heap->collector_policy());
2163
2164 size_policy->decay_supplemental_growth(true /* full gc*/);
2165
2166 heap->resize_old_gen(
2167 size_policy->calculated_old_free_size_in_bytes());
2168
2169 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
2170 size_policy->calculated_survivor_size_in_bytes());
2171 }
2172 if (PrintAdaptiveSizePolicy) {
2173 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
2174 heap->total_collections());
2175 }
2176 }
2177
2178 if (UsePerfData) {
2179 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
2180 counters->update_counters();
2181 counters->update_old_capacity(old_gen->capacity_in_bytes());
2182 counters->update_young_capacity(young_gen->capacity_in_bytes());
2183 }
2184
2185 heap->resize_all_tlabs();
2186
2187 // Resize the metaspace capacity after a collection
2188 MetaspaceGC::compute_new_size();
2189
2190 if (TraceOldGenTime) accumulated_time()->stop();
2191
2192 if (PrintGC) {
2193 if (PrintGCDetails) {
2194 // No GC timestamp here. This is after GC so it would be confusing.
2195 young_gen->print_used_change(pre_gc_values.young_gen_used());
2196 old_gen->print_used_change(pre_gc_values.old_gen_used());
2197 heap->print_heap_change(pre_gc_values.heap_used());
2198 MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used());
2199 } else {
2200 heap->print_heap_change(pre_gc_values.heap_used());
2201 }
2202 }
2203
2204 // Track memory usage and detect low memory
2205 MemoryService::track_memory_usage();
2206 heap->update_counters();
2207 gc_task_manager()->release_idle_workers();
2208 }
2209
2210 #ifdef ASSERT
2211 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
2212 ParCompactionManager* const cm =
2213 ParCompactionManager::manager_array(int(i));
2214 assert(cm->marking_stack()->is_empty(), "should be empty");
2215 assert(ParCompactionManager::region_list(int(i))->is_empty(), "should be empty");
2216 }
2217 #endif // ASSERT
2218
2219 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
2220 HandleMark hm; // Discard invalid handles created during verification
2221 Universe::verify(" VerifyAfterGC:");
2222 }
2223
2224 // Re-verify object start arrays
2225 if (VerifyObjectStartArray &&
2226 VerifyAfterGC) {
2227 old_gen->verify_object_start_array();
2228 }
2229
2230 if (ZapUnusedHeapArea) {
2231 old_gen->object_space()->check_mangled_unused_area_complete();
2232 }
2233
2234 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
2235
2236 collection_exit.update();
2237
2238 heap->print_heap_after_gc();
2239 heap->trace_heap_after_gc(&_gc_tracer);
2240
2241 if (PrintGCTaskTimeStamps) {
2242 gclog_or_tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " "
2243 INT64_FORMAT,
2244 marking_start.ticks(), compaction_start.ticks(),
2245 collection_exit.ticks());
2246 gc_task_manager()->print_task_time_stamps();
2247 }
2248
2249 heap->post_full_gc_dump(&_gc_timer);
2250
2251 #ifdef TRACESPINNING
2252 ParallelTaskTerminator::print_termination_counts();
2253 #endif
2254
2255 _gc_timer.register_gc_end();
2256
2257 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
2258 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
2259
2260 return true;
2261 }
2262
2263 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
2264 PSYoungGen* young_gen,
2265 PSOldGen* old_gen) {
2266 MutableSpace* const eden_space = young_gen->eden_space();
2267 assert(!eden_space->is_empty(), "eden must be non-empty");
2268 assert(young_gen->virtual_space()->alignment() ==
2269 old_gen->virtual_space()->alignment(), "alignments do not match");
2270
2271 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
2272 return false;
2273 }
2274
2275 // Both generations must be completely committed.
2276 if (young_gen->virtual_space()->uncommitted_size() != 0) {
2277 return false;
2278 }
2279 if (old_gen->virtual_space()->uncommitted_size() != 0) {
2280 return false;
2281 }
2282
2283 // Figure out how much to take from eden. Include the average amount promoted
2284 // in the total; otherwise the next young gen GC will simply bail out to a
2285 // full GC.
2286 const size_t alignment = old_gen->virtual_space()->alignment();
2287 const size_t eden_used = eden_space->used_in_bytes();
2288 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
2289 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
2290 const size_t eden_capacity = eden_space->capacity_in_bytes();
2291
2292 if (absorb_size >= eden_capacity) {
2293 return false; // Must leave some space in eden.
2294 }
2295
2296 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2297 if (new_young_size < young_gen->min_gen_size()) {
2298 return false; // Respect young gen minimum size.
2299 }
2300
2301 if (TraceAdaptiveGCBoundary && Verbose) {
2302 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
2303 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2304 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2305 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2306 absorb_size / K,
2307 eden_capacity / K, (eden_capacity - absorb_size) / K,
2308 young_gen->from_space()->used_in_bytes() / K,
2309 young_gen->to_space()->used_in_bytes() / K,
2310 young_gen->capacity_in_bytes() / K, new_young_size / K);
2311 }
2312
2313 // Fill the unused part of the old gen.
2314 MutableSpace* const old_space = old_gen->object_space();
2315 HeapWord* const unused_start = old_space->top();
2316 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2317
2318 if (unused_words > 0) {
2319 if (unused_words < CollectedHeap::min_fill_size()) {
2320 return false; // If the old gen cannot be filled, must give up.
2321 }
2322 CollectedHeap::fill_with_objects(unused_start, unused_words);
2323 }
2324
2325 // Take the live data from eden and set both top and end in the old gen to
2326 // eden top. (Need to set end because reset_after_change() mangles the region
2327 // from end to virtual_space->high() in debug builds).
2328 HeapWord* const new_top = eden_space->top();
2329 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2330 absorb_size);
2331 young_gen->reset_after_change();
2332 old_space->set_top(new_top);
2333 old_space->set_end(new_top);
2334 old_gen->reset_after_change();
2335
2336 // Update the object start array for the filler object and the data from eden.
2337 ObjectStartArray* const start_array = old_gen->start_array();
2338 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2339 start_array->allocate_block(p);
2340 }
2341
2342 // Could update the promoted average here, but it is not typically updated at
2343 // full GCs and the value to use is unclear. Something like
2344 //
2345 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2346
2347 size_policy->set_bytes_absorbed_from_eden(absorb_size);
2348 return true;
2349 }
2350
2351 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2352 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2353 "shouldn't return NULL");
2354 return ParallelScavengeHeap::gc_task_manager();
2355 }
2356
2357 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2358 bool maximum_heap_compaction,
2359 ParallelOldTracer *gc_tracer) {
2360 // Recursively traverse all live objects and mark them
2361 GCTraceTime tm("marking phase", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2362
2363 ParallelScavengeHeap* heap = gc_heap();
2364 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2365 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2366 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2367 ParallelTaskTerminator terminator(active_gc_threads, qset);
2368
2369 PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
2370 PSParallelCompact::FollowStackClosure follow_stack_closure(cm);
2371
2372 // Need new claim bits before marking starts.
2373 ClassLoaderDataGraph::clear_claimed_marks();
2374
2375 {
2376 GCTraceTime tm_m("par mark", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2377
2378 ParallelScavengeHeap::ParStrongRootsScope psrs;
2379
2380 GCTaskQueue* q = GCTaskQueue::create();
2381
2382 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2383 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2384 // We scan the thread roots in parallel
2385 Threads::create_thread_roots_marking_tasks(q);
2386 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2387 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
2388 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2389 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2390 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data));
2391 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2392 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2393
2394 if (active_gc_threads > 1) {
2395 for (uint j = 0; j < active_gc_threads; j++) {
2396 q->enqueue(new StealMarkingTask(&terminator));
2397 }
2398 }
2399
2400 gc_task_manager()->execute_and_wait(q);
2401 }
2402
2403 // Process reference objects found during marking
2404 {
2405 GCTraceTime tm_r("reference processing", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2406
2407 ReferenceProcessorStats stats;
2408 if (ref_processor()->processing_is_mt()) {
2409 RefProcTaskExecutor task_executor;
2410 stats = ref_processor()->process_discovered_references(
2411 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2412 &task_executor, &_gc_timer, _gc_tracer.gc_id());
2413 } else {
2414 stats = ref_processor()->process_discovered_references(
2415 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
2416 &_gc_timer, _gc_tracer.gc_id());
2417 }
2418
2419 gc_tracer->report_gc_reference_stats(stats);
2420 }
2421
2422 GCTraceTime tm_c("class unloading", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2423
2424 // This is the point where the entire marking should have completed.
2425 assert(cm->marking_stacks_empty(), "Marking should have completed");
2426
2427 // Follow system dictionary roots and unload classes.
2428 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
2429
2430 // Unload nmethods.
2431 CodeCache::do_unloading(is_alive_closure(), purged_class);
2432
2433 // Prune dead klasses from subklass/sibling/implementor lists.
2434 Klass::clean_weak_klass_links(is_alive_closure());
2435
2436 // Delete entries for dead interned strings.
2437 StringTable::unlink(is_alive_closure());
2438
2439 // Clean up unreferenced symbols in symbol table.
2440 SymbolTable::unlink();
2441 _gc_tracer.report_object_count_after_gc(is_alive_closure());
2442 }
2443
2444 void PSParallelCompact::follow_class_loader(ParCompactionManager* cm,
2445 ClassLoaderData* cld) {
2446 PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
2447 PSParallelCompact::FollowKlassClosure follow_klass_closure(&mark_and_push_closure);
2448
2449 cld->oops_do(&mark_and_push_closure, &follow_klass_closure, true);
2450 }
2451
2452 // This should be moved to the shared markSweep code!
2453 class PSAlwaysTrueClosure: public BoolObjectClosure {
2454 public:
2455 bool do_object_b(oop p) { return true; }
2456 };
2457 static PSAlwaysTrueClosure always_true;
2458
2459 void PSParallelCompact::adjust_roots() {
2460 // Adjust the pointers to reflect the new locations
2461 GCTraceTime tm("adjust roots", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2462
2463 // Need new claim bits when tracing through and adjusting pointers.
2464 ClassLoaderDataGraph::clear_claimed_marks();
2465
2466 // General strong roots.
2467 Universe::oops_do(adjust_pointer_closure());
2468 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
2469 CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
2470 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
2471 ObjectSynchronizer::oops_do(adjust_pointer_closure());
2472 FlatProfiler::oops_do(adjust_pointer_closure());
2473 Management::oops_do(adjust_pointer_closure());
2474 JvmtiExport::oops_do(adjust_pointer_closure());
2475 SystemDictionary::oops_do(adjust_pointer_closure());
2476 ClassLoaderDataGraph::oops_do(adjust_pointer_closure(), adjust_klass_closure(), true);
2477
2478 // Now adjust pointers in remaining weak roots. (All of which should
2479 // have been cleared if they pointed to non-surviving objects.)
2480 // Global (weak) JNI handles
2481 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure());
2482
2483 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations);
2484 CodeCache::blobs_do(&adjust_from_blobs);
2485 StringTable::oops_do(adjust_pointer_closure());
2486 ref_processor()->weak_oops_do(adjust_pointer_closure());
2487 // Roots were visited so references into the young gen in roots
2488 // may have been scanned. Process them also.
2489 // Should the reference processor have a span that excludes
2490 // young gen objects?
2491 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
2492 }
2493
2494 void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q,
2495 uint parallel_gc_threads)
2496 {
2497 GCTraceTime tm("drain task setup", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2498
2499 // Find the threads that are active
2500 unsigned int which = 0;
2501
2502 const uint task_count = MAX2(parallel_gc_threads, 1U);
2503 for (uint j = 0; j < task_count; j++) {
2504 q->enqueue(new DrainStacksCompactionTask(j));
2505 ParCompactionManager::verify_region_list_empty(j);
2506 // Set the region stacks variables to "no" region stack values
2507 // so that they will be recognized and needing a region stack
2508 // in the stealing tasks if they do not get one by executing
2509 // a draining stack.
2510 ParCompactionManager* cm = ParCompactionManager::manager_array(j);
2511 cm->set_region_stack(NULL);
2512 cm->set_region_stack_index((uint)max_uintx);
2513 }
2514 ParCompactionManager::reset_recycled_stack_index();
2515
2516 // Find all regions that are available (can be filled immediately) and
2517 // distribute them to the thread stacks. The iteration is done in reverse
2518 // order (high to low) so the regions will be removed in ascending order.
2519
2520 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2521
2522 size_t fillable_regions = 0; // A count for diagnostic purposes.
2523 // A region index which corresponds to the tasks created above.
2524 // "which" must be 0 <= which < task_count
2525
2526 which = 0;
2527 // id + 1 is used to test termination so unsigned can
2528 // be used with an old_space_id == 0.
2529 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2530 SpaceInfo* const space_info = _space_info + id;
2531 MutableSpace* const space = space_info->space();
2532 HeapWord* const new_top = space_info->new_top();
2533
2534 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2535 const size_t end_region =
2536 sd.addr_to_region_idx(sd.region_align_up(new_top));
2537
2538 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2539 if (sd.region(cur)->claim_unsafe()) {
2540 ParCompactionManager::region_list_push(which, cur);
2541
2542 if (TraceParallelOldGCCompactionPhase && Verbose) {
2543 const size_t count_mod_8 = fillable_regions & 7;
2544 if (count_mod_8 == 0) gclog_or_tty->print("fillable: ");
2545 gclog_or_tty->print(" " SIZE_FORMAT_W(7), cur);
2546 if (count_mod_8 == 7) gclog_or_tty->cr();
2547 }
2548
2549 NOT_PRODUCT(++fillable_regions;)
2550
2551 // Assign regions to tasks in round-robin fashion.
2552 if (++which == task_count) {
2553 assert(which <= parallel_gc_threads,
2554 "Inconsistent number of workers");
2555 which = 0;
2556 }
2557 }
2558 }
2559 }
2560
2561 if (TraceParallelOldGCCompactionPhase) {
2562 if (Verbose && (fillable_regions & 7) != 0) gclog_or_tty->cr();
2563 gclog_or_tty->print_cr(SIZE_FORMAT " initially fillable regions", fillable_regions);
2564 }
2565 }
2566
2567 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2568
2569 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2570 uint parallel_gc_threads) {
2571 GCTraceTime tm("dense prefix task setup", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2572
2573 ParallelCompactData& sd = PSParallelCompact::summary_data();
2574
2575 // Iterate over all the spaces adding tasks for updating
2576 // regions in the dense prefix. Assume that 1 gc thread
2577 // will work on opening the gaps and the remaining gc threads
2578 // will work on the dense prefix.
2579 unsigned int space_id;
2580 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2581 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2582 const MutableSpace* const space = _space_info[space_id].space();
2583
2584 if (dense_prefix_end == space->bottom()) {
2585 // There is no dense prefix for this space.
2586 continue;
2587 }
2588
2589 // The dense prefix is before this region.
2590 size_t region_index_end_dense_prefix =
2591 sd.addr_to_region_idx(dense_prefix_end);
2592 RegionData* const dense_prefix_cp =
2593 sd.region(region_index_end_dense_prefix);
2594 assert(dense_prefix_end == space->end() ||
2595 dense_prefix_cp->available() ||
2596 dense_prefix_cp->claimed(),
2597 "The region after the dense prefix should always be ready to fill");
2598
2599 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2600
2601 // Is there dense prefix work?
2602 size_t total_dense_prefix_regions =
2603 region_index_end_dense_prefix - region_index_start;
2604 // How many regions of the dense prefix should be given to
2605 // each thread?
2606 if (total_dense_prefix_regions > 0) {
2607 uint tasks_for_dense_prefix = 1;
2608 if (total_dense_prefix_regions <=
2609 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2610 // Don't over partition. This assumes that
2611 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2612 // so there are not many regions to process.
2613 tasks_for_dense_prefix = parallel_gc_threads;
2614 } else {
2615 // Over partition
2616 tasks_for_dense_prefix = parallel_gc_threads *
2617 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2618 }
2619 size_t regions_per_thread = total_dense_prefix_regions /
2620 tasks_for_dense_prefix;
2621 // Give each thread at least 1 region.
2622 if (regions_per_thread == 0) {
2623 regions_per_thread = 1;
2624 }
2625
2626 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2627 if (region_index_start >= region_index_end_dense_prefix) {
2628 break;
2629 }
2630 // region_index_end is not processed
2631 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2632 region_index_end_dense_prefix);
2633 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2634 region_index_start,
2635 region_index_end));
2636 region_index_start = region_index_end;
2637 }
2638 }
2639 // This gets any part of the dense prefix that did not
2640 // fit evenly.
2641 if (region_index_start < region_index_end_dense_prefix) {
2642 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2643 region_index_start,
2644 region_index_end_dense_prefix));
2645 }
2646 }
2647 }
2648
2649 void PSParallelCompact::enqueue_region_stealing_tasks(
2650 GCTaskQueue* q,
2651 ParallelTaskTerminator* terminator_ptr,
2652 uint parallel_gc_threads) {
2653 GCTraceTime tm("steal task setup", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2654
2655 // Once a thread has drained it's stack, it should try to steal regions from
2656 // other threads.
2657 if (parallel_gc_threads > 1) {
2658 for (uint j = 0; j < parallel_gc_threads; j++) {
2659 q->enqueue(new StealRegionCompactionTask(terminator_ptr));
2660 }
2661 }
2662 }
2663
2664 #ifdef ASSERT
2665 // Write a histogram of the number of times the block table was filled for a
2666 // region.
2667 void PSParallelCompact::write_block_fill_histogram(outputStream* const out)
2668 {
2669 if (!TraceParallelOldGCCompactionPhase) return;
2670
2671 typedef ParallelCompactData::RegionData rd_t;
2672 ParallelCompactData& sd = summary_data();
2673
2674 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2675 MutableSpace* const spc = _space_info[id].space();
2676 if (spc->bottom() != spc->top()) {
2677 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
2678 HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
2679 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
2680
2681 size_t histo[5] = { 0, 0, 0, 0, 0 };
2682 const size_t histo_len = sizeof(histo) / sizeof(size_t);
2683 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
2684
2685 for (const rd_t* cur = beg; cur < end; ++cur) {
2686 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
2687 }
2688 out->print("%u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
2689 for (size_t i = 0; i < histo_len; ++i) {
2690 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
2691 histo[i], 100.0 * histo[i] / region_cnt);
2692 }
2693 out->cr();
2694 }
2695 }
2696 }
2697 #endif // #ifdef ASSERT
2698
2699 void PSParallelCompact::compact() {
2700 // trace("5");
2701 GCTraceTime tm("compaction phase", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2702
2703 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
2704 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
2705 PSOldGen* old_gen = heap->old_gen();
2706 old_gen->start_array()->reset();
2707 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2708 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2709 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2710 ParallelTaskTerminator terminator(active_gc_threads, qset);
2711
2712 GCTaskQueue* q = GCTaskQueue::create();
2713 enqueue_region_draining_tasks(q, active_gc_threads);
2714 enqueue_dense_prefix_tasks(q, active_gc_threads);
2715 enqueue_region_stealing_tasks(q, &terminator, active_gc_threads);
2716
2717 {
2718 GCTraceTime tm_pc("par compact", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2719
2720 gc_task_manager()->execute_and_wait(q);
2721
2722 #ifdef ASSERT
2723 // Verify that all regions have been processed before the deferred updates.
2724 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2725 verify_complete(SpaceId(id));
2726 }
2727 #endif
2728 }
2729
2730 {
2731 // Update the deferred objects, if any. Any compaction manager can be used.
2732 GCTraceTime tm_du("deferred updates", print_phases(), true, &_gc_timer, _gc_tracer.gc_id());
2733 ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2734 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2735 update_deferred_objects(cm, SpaceId(id));
2736 }
2737 }
2738
2739 DEBUG_ONLY(write_block_fill_histogram(gclog_or_tty));
2740 }
2741
2742 #ifdef ASSERT
2743 void PSParallelCompact::verify_complete(SpaceId space_id) {
2744 // All Regions between space bottom() to new_top() should be marked as filled
2745 // and all Regions between new_top() and top() should be available (i.e.,
2746 // should have been emptied).
2747 ParallelCompactData& sd = summary_data();
2748 SpaceInfo si = _space_info[space_id];
2749 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2750 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2751 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2752 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2753 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2754
2755 bool issued_a_warning = false;
2756
2757 size_t cur_region;
2758 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2759 const RegionData* const c = sd.region(cur_region);
2760 if (!c->completed()) {
2761 warning("region " SIZE_FORMAT " not filled: "
2762 "destination_count=" SIZE_FORMAT,
2763 cur_region, c->destination_count());
2764 issued_a_warning = true;
2765 }
2766 }
2767
2768 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2769 const RegionData* const c = sd.region(cur_region);
2770 if (!c->available()) {
2771 warning("region " SIZE_FORMAT " not empty: "
2772 "destination_count=" SIZE_FORMAT,
2773 cur_region, c->destination_count());
2774 issued_a_warning = true;
2775 }
2776 }
2777
2778 if (issued_a_warning) {
2779 print_region_ranges();
2780 }
2781 }
2782 #endif // #ifdef ASSERT
2783
2784 // Update interior oops in the ranges of regions [beg_region, end_region).
2785 void
2786 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2787 SpaceId space_id,
2788 size_t beg_region,
2789 size_t end_region) {
2790 ParallelCompactData& sd = summary_data();
2791 ParMarkBitMap* const mbm = mark_bitmap();
2792
2793 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2794 HeapWord* const end_addr = sd.region_to_addr(end_region);
2795 assert(beg_region <= end_region, "bad region range");
2796 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2797
2798 #ifdef ASSERT
2799 // Claim the regions to avoid triggering an assert when they are marked as
2800 // filled.
2801 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2802 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2803 }
2804 #endif // #ifdef ASSERT
2805
2806 if (beg_addr != space(space_id)->bottom()) {
2807 // Find the first live object or block of dead space that *starts* in this
2808 // range of regions. If a partial object crosses onto the region, skip it;
2809 // it will be marked for 'deferred update' when the object head is
2810 // processed. If dead space crosses onto the region, it is also skipped; it
2811 // will be filled when the prior region is processed. If neither of those
2812 // apply, the first word in the region is the start of a live object or dead
2813 // space.
2814 assert(beg_addr > space(space_id)->bottom(), "sanity");
2815 const RegionData* const cp = sd.region(beg_region);
2816 if (cp->partial_obj_size() != 0) {
2817 beg_addr = sd.partial_obj_end(beg_region);
2818 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2819 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2820 }
2821 }
2822
2823 if (beg_addr < end_addr) {
2824 // A live object or block of dead space starts in this range of Regions.
2825 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2826
2827 // Create closures and iterate.
2828 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2829 FillClosure fill_closure(cm, space_id);
2830 ParMarkBitMap::IterationStatus status;
2831 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2832 dense_prefix_end);
2833 if (status == ParMarkBitMap::incomplete) {
2834 update_closure.do_addr(update_closure.source());
2835 }
2836 }
2837
2838 // Mark the regions as filled.
2839 RegionData* const beg_cp = sd.region(beg_region);
2840 RegionData* const end_cp = sd.region(end_region);
2841 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2842 cp->set_completed();
2843 }
2844 }
2845
2846 // Return the SpaceId for the space containing addr. If addr is not in the
2847 // heap, last_space_id is returned. In debug mode it expects the address to be
2848 // in the heap and asserts such.
2849 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2850 assert(Universe::heap()->is_in_reserved(addr), "addr not in the heap");
2851
2852 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2853 if (_space_info[id].space()->contains(addr)) {
2854 return SpaceId(id);
2855 }
2856 }
2857
2858 assert(false, "no space contains the addr");
2859 return last_space_id;
2860 }
2861
2862 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2863 SpaceId id) {
2864 assert(id < last_space_id, "bad space id");
2865
2866 ParallelCompactData& sd = summary_data();
2867 const SpaceInfo* const space_info = _space_info + id;
2868 ObjectStartArray* const start_array = space_info->start_array();
2869
2870 const MutableSpace* const space = space_info->space();
2871 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2872 HeapWord* const beg_addr = space_info->dense_prefix();
2873 HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2874
2875 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2876 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2877 const RegionData* cur_region;
2878 for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2879 HeapWord* const addr = cur_region->deferred_obj_addr();
2880 if (addr != NULL) {
2881 if (start_array != NULL) {
2882 start_array->allocate_block(addr);
2883 }
2884 oop(addr)->update_contents(cm);
2885 assert(oop(addr)->is_oop_or_null(), "should be an oop now");
2886 }
2887 }
2888 }
2889
2890 // Skip over count live words starting from beg, and return the address of the
2891 // next live word. Unless marked, the word corresponding to beg is assumed to
2892 // be dead. Callers must either ensure beg does not correspond to the middle of
2893 // an object, or account for those live words in some other way. Callers must
2894 // also ensure that there are enough live words in the range [beg, end) to skip.
2895 HeapWord*
2896 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2897 {
2898 assert(count > 0, "sanity");
2899
2900 ParMarkBitMap* m = mark_bitmap();
2901 idx_t bits_to_skip = m->words_to_bits(count);
2902 idx_t cur_beg = m->addr_to_bit(beg);
2903 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
2904
2905 do {
2906 cur_beg = m->find_obj_beg(cur_beg, search_end);
2907 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2908 const size_t obj_bits = cur_end - cur_beg + 1;
2909 if (obj_bits > bits_to_skip) {
2910 return m->bit_to_addr(cur_beg + bits_to_skip);
2911 }
2912 bits_to_skip -= obj_bits;
2913 cur_beg = cur_end + 1;
2914 } while (bits_to_skip > 0);
2915
2916 // Skipping the desired number of words landed just past the end of an object.
2917 // Find the start of the next object.
2918 cur_beg = m->find_obj_beg(cur_beg, search_end);
2919 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2920 return m->bit_to_addr(cur_beg);
2921 }
2922
2923 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2924 SpaceId src_space_id,
2925 size_t src_region_idx)
2926 {
2927 assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2928
2929 const SplitInfo& split_info = _space_info[src_space_id].split_info();
2930 if (split_info.dest_region_addr() == dest_addr) {
2931 // The partial object ending at the split point contains the first word to
2932 // be copied to dest_addr.
2933 return split_info.first_src_addr();
2934 }
2935
2936 const ParallelCompactData& sd = summary_data();
2937 ParMarkBitMap* const bitmap = mark_bitmap();
2938 const size_t RegionSize = ParallelCompactData::RegionSize;
2939
2940 assert(sd.is_region_aligned(dest_addr), "not aligned");
2941 const RegionData* const src_region_ptr = sd.region(src_region_idx);
2942 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2943 HeapWord* const src_region_destination = src_region_ptr->destination();
2944
2945 assert(dest_addr >= src_region_destination, "wrong src region");
2946 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2947
2948 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2949 HeapWord* const src_region_end = src_region_beg + RegionSize;
2950
2951 HeapWord* addr = src_region_beg;
2952 if (dest_addr == src_region_destination) {
2953 // Return the first live word in the source region.
2954 if (partial_obj_size == 0) {
2955 addr = bitmap->find_obj_beg(addr, src_region_end);
2956 assert(addr < src_region_end, "no objects start in src region");
2957 }
2958 return addr;
2959 }
2960
2961 // Must skip some live data.
2962 size_t words_to_skip = dest_addr - src_region_destination;
2963 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2964
2965 if (partial_obj_size >= words_to_skip) {
2966 // All the live words to skip are part of the partial object.
2967 addr += words_to_skip;
2968 if (partial_obj_size == words_to_skip) {
2969 // Find the first live word past the partial object.
2970 addr = bitmap->find_obj_beg(addr, src_region_end);
2971 assert(addr < src_region_end, "wrong src region");
2972 }
2973 return addr;
2974 }
2975
2976 // Skip over the partial object (if any).
2977 if (partial_obj_size != 0) {
2978 words_to_skip -= partial_obj_size;
2979 addr += partial_obj_size;
2980 }
2981
2982 // Skip over live words due to objects that start in the region.
2983 addr = skip_live_words(addr, src_region_end, words_to_skip);
2984 assert(addr < src_region_end, "wrong src region");
2985 return addr;
2986 }
2987
2988 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2989 SpaceId src_space_id,
2990 size_t beg_region,
2991 HeapWord* end_addr)
2992 {
2993 ParallelCompactData& sd = summary_data();
2994
2995 #ifdef ASSERT
2996 MutableSpace* const src_space = _space_info[src_space_id].space();
2997 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2998 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2999 "src_space_id does not match beg_addr");
3000 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
3001 "src_space_id does not match end_addr");
3002 #endif // #ifdef ASSERT
3003
3004 RegionData* const beg = sd.region(beg_region);
3005 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
3006
3007 // Regions up to new_top() are enqueued if they become available.
3008 HeapWord* const new_top = _space_info[src_space_id].new_top();
3009 RegionData* const enqueue_end =
3010 sd.addr_to_region_ptr(sd.region_align_up(new_top));
3011
3012 for (RegionData* cur = beg; cur < end; ++cur) {
3013 assert(cur->data_size() > 0, "region must have live data");
3014 cur->decrement_destination_count();
3015 if (cur < enqueue_end && cur->available() && cur->claim()) {
3016 cm->push_region(sd.region(cur));
3017 }
3018 }
3019 }
3020
3021 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
3022 SpaceId& src_space_id,
3023 HeapWord*& src_space_top,
3024 HeapWord* end_addr)
3025 {
3026 typedef ParallelCompactData::RegionData RegionData;
3027
3028 ParallelCompactData& sd = PSParallelCompact::summary_data();
3029 const size_t region_size = ParallelCompactData::RegionSize;
3030
3031 size_t src_region_idx = 0;
3032
3033 // Skip empty regions (if any) up to the top of the space.
3034 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
3035 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
3036 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
3037 const RegionData* const top_region_ptr =
3038 sd.addr_to_region_ptr(top_aligned_up);
3039 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
3040 ++src_region_ptr;
3041 }
3042
3043 if (src_region_ptr < top_region_ptr) {
3044 // The next source region is in the current space. Update src_region_idx
3045 // and the source address to match src_region_ptr.
3046 src_region_idx = sd.region(src_region_ptr);
3047 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
3048 if (src_region_addr > closure.source()) {
3049 closure.set_source(src_region_addr);
3050 }
3051 return src_region_idx;
3052 }
3053
3054 // Switch to a new source space and find the first non-empty region.
3055 unsigned int space_id = src_space_id + 1;
3056 assert(space_id < last_space_id, "not enough spaces");
3057
3058 HeapWord* const destination = closure.destination();
3059
3060 do {
3061 MutableSpace* space = _space_info[space_id].space();
3062 HeapWord* const bottom = space->bottom();
3063 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
3064
3065 // Iterate over the spaces that do not compact into themselves.
3066 if (bottom_cp->destination() != bottom) {
3067 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
3068 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
3069
3070 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
3071 if (src_cp->live_obj_size() > 0) {
3072 // Found it.
3073 assert(src_cp->destination() == destination,
3074 "first live obj in the space must match the destination");
3075 assert(src_cp->partial_obj_size() == 0,
3076 "a space cannot begin with a partial obj");
3077
3078 src_space_id = SpaceId(space_id);
3079 src_space_top = space->top();
3080 const size_t src_region_idx = sd.region(src_cp);
3081 closure.set_source(sd.region_to_addr(src_region_idx));
3082 return src_region_idx;
3083 } else {
3084 assert(src_cp->data_size() == 0, "sanity");
3085 }
3086 }
3087 }
3088 } while (++space_id < last_space_id);
3089
3090 assert(false, "no source region was found");
3091 return 0;
3092 }
3093
3094 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
3095 {
3096 typedef ParMarkBitMap::IterationStatus IterationStatus;
3097 const size_t RegionSize = ParallelCompactData::RegionSize;
3098 ParMarkBitMap* const bitmap = mark_bitmap();
3099 ParallelCompactData& sd = summary_data();
3100 RegionData* const region_ptr = sd.region(region_idx);
3101
3102 // Get the items needed to construct the closure.
3103 HeapWord* dest_addr = sd.region_to_addr(region_idx);
3104 SpaceId dest_space_id = space_id(dest_addr);
3105 ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
3106 HeapWord* new_top = _space_info[dest_space_id].new_top();
3107 assert(dest_addr < new_top, "sanity");
3108 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
3109
3110 // Get the source region and related info.
3111 size_t src_region_idx = region_ptr->source_region();
3112 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
3113 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
3114
3115 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3116 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
3117
3118 // Adjust src_region_idx to prepare for decrementing destination counts (the
3119 // destination count is not decremented when a region is copied to itself).
3120 if (src_region_idx == region_idx) {
3121 src_region_idx += 1;
3122 }
3123
3124 if (bitmap->is_unmarked(closure.source())) {
3125 // The first source word is in the middle of an object; copy the remainder
3126 // of the object or as much as will fit. The fact that pointer updates were
3127 // deferred will be noted when the object header is processed.
3128 HeapWord* const old_src_addr = closure.source();
3129 closure.copy_partial_obj();
3130 if (closure.is_full()) {
3131 decrement_destination_counts(cm, src_space_id, src_region_idx,
3132 closure.source());
3133 region_ptr->set_deferred_obj_addr(NULL);
3134 region_ptr->set_completed();
3135 return;
3136 }
3137
3138 HeapWord* const end_addr = sd.region_align_down(closure.source());
3139 if (sd.region_align_down(old_src_addr) != end_addr) {
3140 // The partial object was copied from more than one source region.
3141 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3142
3143 // Move to the next source region, possibly switching spaces as well. All
3144 // args except end_addr may be modified.
3145 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3146 end_addr);
3147 }
3148 }
3149
3150 do {
3151 HeapWord* const cur_addr = closure.source();
3152 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
3153 src_space_top);
3154 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
3155
3156 if (status == ParMarkBitMap::incomplete) {
3157 // The last obj that starts in the source region does not end in the
3158 // region.
3159 assert(closure.source() < end_addr, "sanity");
3160 HeapWord* const obj_beg = closure.source();
3161 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
3162 src_space_top);
3163 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
3164 if (obj_end < range_end) {
3165 // The end was found; the entire object will fit.
3166 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
3167 assert(status != ParMarkBitMap::would_overflow, "sanity");
3168 } else {
3169 // The end was not found; the object will not fit.
3170 assert(range_end < src_space_top, "obj cannot cross space boundary");
3171 status = ParMarkBitMap::would_overflow;
3172 }
3173 }
3174
3175 if (status == ParMarkBitMap::would_overflow) {
3176 // The last object did not fit. Note that interior oop updates were
3177 // deferred, then copy enough of the object to fill the region.
3178 region_ptr->set_deferred_obj_addr(closure.destination());
3179 status = closure.copy_until_full(); // copies from closure.source()
3180
3181 decrement_destination_counts(cm, src_space_id, src_region_idx,
3182 closure.source());
3183 region_ptr->set_completed();
3184 return;
3185 }
3186
3187 if (status == ParMarkBitMap::full) {
3188 decrement_destination_counts(cm, src_space_id, src_region_idx,
3189 closure.source());
3190 region_ptr->set_deferred_obj_addr(NULL);
3191 region_ptr->set_completed();
3192 return;
3193 }
3194
3195 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3196
3197 // Move to the next source region, possibly switching spaces as well. All
3198 // args except end_addr may be modified.
3199 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3200 end_addr);
3201 } while (true);
3202 }
3203
3204 void PSParallelCompact::fill_blocks(size_t region_idx)
3205 {
3206 // Fill in the block table elements for the specified region. Each block
3207 // table element holds the number of live words in the region that are to the
3208 // left of the first object that starts in the block. Thus only blocks in
3209 // which an object starts need to be filled.
3210 //
3211 // The algorithm scans the section of the bitmap that corresponds to the
3212 // region, keeping a running total of the live words. When an object start is
3213 // found, if it's the first to start in the block that contains it, the
3214 // current total is written to the block table element.
3215 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
3216 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
3217 const size_t RegionSize = ParallelCompactData::RegionSize;
3218
3219 ParallelCompactData& sd = summary_data();
3220 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
3221 if (partial_obj_size >= RegionSize) {
3222 return; // No objects start in this region.
3223 }
3224
3225 // Ensure the first loop iteration decides that the block has changed.
3226 size_t cur_block = sd.block_count();
3227
3228 const ParMarkBitMap* const bitmap = mark_bitmap();
3229
3230 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
3231 assert((size_t)1 << Log2BitsPerBlock ==
3232 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
3233
3234 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
3235 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
3236 size_t live_bits = bitmap->words_to_bits(partial_obj_size);
3237 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
3238 while (beg_bit < range_end) {
3239 const size_t new_block = beg_bit >> Log2BitsPerBlock;
3240 if (new_block != cur_block) {
3241 cur_block = new_block;
3242 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
3243 }
3244
3245 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
3246 if (end_bit < range_end - 1) {
3247 live_bits += end_bit - beg_bit + 1;
3248 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
3249 } else {
3250 return;
3251 }
3252 }
3253 }
3254
3255 void
3256 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
3257 const MutableSpace* sp = space(space_id);
3258 if (sp->is_empty()) {
3259 return;
3260 }
3261
3262 ParallelCompactData& sd = PSParallelCompact::summary_data();
3263 ParMarkBitMap* const bitmap = mark_bitmap();
3264 HeapWord* const dp_addr = dense_prefix(space_id);
3265 HeapWord* beg_addr = sp->bottom();
3266 HeapWord* end_addr = sp->top();
3267
3268 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
3269
3270 const size_t beg_region = sd.addr_to_region_idx(beg_addr);
3271 const size_t dp_region = sd.addr_to_region_idx(dp_addr);
3272 if (beg_region < dp_region) {
3273 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
3274 }
3275
3276 // The destination of the first live object that starts in the region is one
3277 // past the end of the partial object entering the region (if any).
3278 HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3279 HeapWord* const new_top = _space_info[space_id].new_top();
3280 assert(new_top >= dest_addr, "bad new_top value");
3281 const size_t words = pointer_delta(new_top, dest_addr);
3282
3283 if (words > 0) {
3284 ObjectStartArray* start_array = _space_info[space_id].start_array();
3285 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3286
3287 ParMarkBitMap::IterationStatus status;
3288 status = bitmap->iterate(&closure, dest_addr, end_addr);
3289 assert(status == ParMarkBitMap::full, "iteration not complete");
3290 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3291 "live objects skipped because closure is full");
3292 }
3293 }
3294
3295 jlong PSParallelCompact::millis_since_last_gc() {
3296 // We need a monotonically non-decreasing time in ms but
3297 // os::javaTimeMillis() does not guarantee monotonicity.
3298 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3299 jlong ret_val = now - _time_of_last_gc;
3300 // XXX See note in genCollectedHeap::millis_since_last_gc().
3301 if (ret_val < 0) {
3302 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, ret_val);)
3303 return 0;
3304 }
3305 return ret_val;
3306 }
3307
3308 void PSParallelCompact::reset_millis_since_last_gc() {
3309 // We need a monotonically non-decreasing time in ms but
3310 // os::javaTimeMillis() does not guarantee monotonicity.
3311 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3312 }
3313
3314 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3315 {
3316 if (source() != destination()) {
3317 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3318 Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3319 }
3320 update_state(words_remaining());
3321 assert(is_full(), "sanity");
3322 return ParMarkBitMap::full;
3323 }
3324
3325 void MoveAndUpdateClosure::copy_partial_obj()
3326 {
3327 size_t words = words_remaining();
3328
3329 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3330 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3331 if (end_addr < range_end) {
3332 words = bitmap()->obj_size(source(), end_addr);
3333 }
3334
3335 // This test is necessary; if omitted, the pointer updates to a partial object
3336 // that crosses the dense prefix boundary could be overwritten.
3337 if (source() != destination()) {
3338 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3339 Copy::aligned_conjoint_words(source(), destination(), words);
3340 }
3341 update_state(words);
3342 }
3343
3344 ParMarkBitMapClosure::IterationStatus
3345 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3346 assert(destination() != NULL, "sanity");
3347 assert(bitmap()->obj_size(addr) == words, "bad size");
3348
3349 _source = addr;
3350 assert(PSParallelCompact::summary_data().calc_new_pointer(source()) ==
3351 destination(), "wrong destination");
3352
3353 if (words > words_remaining()) {
3354 return ParMarkBitMap::would_overflow;
3355 }
3356
3357 // The start_array must be updated even if the object is not moving.
3358 if (_start_array != NULL) {
3359 _start_array->allocate_block(destination());
3360 }
3361
3362 if (destination() != source()) {
3363 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3364 Copy::aligned_conjoint_words(source(), destination(), words);
3365 }
3366
3367 oop moved_oop = (oop) destination();
3368 moved_oop->update_contents(compaction_manager());
3369 assert(moved_oop->is_oop_or_null(), "Object should be whole at this point");
3370
3371 update_state(words);
3372 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3373 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3374 }
3375
3376 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3377 ParCompactionManager* cm,
3378 PSParallelCompact::SpaceId space_id) :
3379 ParMarkBitMapClosure(mbm, cm),
3380 _space_id(space_id),
3381 _start_array(PSParallelCompact::start_array(space_id))
3382 {
3383 }
3384
3385 // Updates the references in the object to their new values.
3386 ParMarkBitMapClosure::IterationStatus
3387 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3388 do_addr(addr);
3389 return ParMarkBitMap::incomplete;
3390 }