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