1 /*
2 * Copyright (c) 2005, 2015, 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.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 "oops/instanceKlass.inline.hpp"
54 #include "oops/instanceMirrorKlass.inline.hpp"
55 #include "oops/methodData.hpp"
56 #include "oops/objArrayKlass.inline.hpp"
57 #include "oops/oop.inline.hpp"
58 #include "runtime/atomic.inline.hpp"
59 #include "runtime/fprofiler.hpp"
60 #include "runtime/safepoint.hpp"
61 #include "runtime/vmThread.hpp"
62 #include "services/management.hpp"
63 #include "services/memTracker.hpp"
64 #include "services/memoryService.hpp"
65 #include "utilities/events.hpp"
66 #include "utilities/stack.inline.hpp"
67
68 #include <math.h>
69
70 // All sizes are in HeapWords.
71 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words
72 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
73 const size_t ParallelCompactData::RegionSizeBytes =
74 RegionSize << LogHeapWordSize;
75 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
76 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
77 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
78
79 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words
80 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize;
81 const size_t ParallelCompactData::BlockSizeBytes =
82 BlockSize << LogHeapWordSize;
83 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1;
84 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1;
85 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask;
86
87 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
88 const size_t ParallelCompactData::Log2BlocksPerRegion =
89 Log2RegionSize - Log2BlockSize;
90
91 const ParallelCompactData::RegionData::region_sz_t
92 ParallelCompactData::RegionData::dc_shift = 27;
93
94 const ParallelCompactData::RegionData::region_sz_t
95 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
96
97 const ParallelCompactData::RegionData::region_sz_t
98 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
99
100 const ParallelCompactData::RegionData::region_sz_t
101 ParallelCompactData::RegionData::los_mask = ~dc_mask;
102
103 const ParallelCompactData::RegionData::region_sz_t
104 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
105
106 const ParallelCompactData::RegionData::region_sz_t
107 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
108
109 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
110 bool PSParallelCompact::_print_phases = false;
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 {
199 tty->print_cr("space bottom top end new_top");
200 tty->print_cr("------ ---------- ---------- ---------- ----------");
201
202 for (unsigned int id = 0; id < last_space_id; ++id) {
203 const MutableSpace* space = _space_info[id].space();
204 tty->print_cr("%u %s "
205 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
206 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
207 id, space_names[id],
208 summary_data().addr_to_region_idx(space->bottom()),
209 summary_data().addr_to_region_idx(space->top()),
210 summary_data().addr_to_region_idx(space->end()),
211 summary_data().addr_to_region_idx(_space_info[id].new_top()));
212 }
213 }
214
215 void
216 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
217 {
218 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7)
219 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5)
220
221 ParallelCompactData& sd = PSParallelCompact::summary_data();
222 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
223 tty->print_cr(REGION_IDX_FORMAT " " PTR_FORMAT " "
224 REGION_IDX_FORMAT " " PTR_FORMAT " "
225 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
226 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
227 i, p2i(c->data_location()), dci, p2i(c->destination()),
228 c->partial_obj_size(), c->live_obj_size(),
229 c->data_size(), c->source_region(), c->destination_count());
230
231 #undef REGION_IDX_FORMAT
232 #undef REGION_DATA_FORMAT
233 }
234
235 void
236 print_generic_summary_data(ParallelCompactData& summary_data,
237 HeapWord* const beg_addr,
238 HeapWord* const end_addr)
239 {
240 size_t total_words = 0;
241 size_t i = summary_data.addr_to_region_idx(beg_addr);
242 const size_t last = summary_data.addr_to_region_idx(end_addr);
243 HeapWord* pdest = 0;
244
245 while (i <= last) {
246 ParallelCompactData::RegionData* c = summary_data.region(i);
247 if (c->data_size() != 0 || c->destination() != pdest) {
248 print_generic_summary_region(i, c);
249 total_words += c->data_size();
250 pdest = c->destination();
251 }
252 ++i;
253 }
254
255 tty->print_cr("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
256 }
257
258 void
259 print_generic_summary_data(ParallelCompactData& summary_data,
260 SpaceInfo* space_info)
261 {
262 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
263 const MutableSpace* space = space_info[id].space();
264 print_generic_summary_data(summary_data, space->bottom(),
265 MAX2(space->top(), space_info[id].new_top()));
266 }
267 }
268
269 void
270 print_initial_summary_region(size_t i,
271 const ParallelCompactData::RegionData* c,
272 bool newline = true)
273 {
274 tty->print(SIZE_FORMAT_W(5) " " PTR_FORMAT " "
275 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " "
276 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
277 i, p2i(c->destination()),
278 c->partial_obj_size(), c->live_obj_size(),
279 c->data_size(), c->source_region(), c->destination_count());
280 if (newline) tty->cr();
281 }
282
283 void
284 print_initial_summary_data(ParallelCompactData& summary_data,
285 const MutableSpace* space) {
286 if (space->top() == space->bottom()) {
287 return;
288 }
289
290 const size_t region_size = ParallelCompactData::RegionSize;
291 typedef ParallelCompactData::RegionData RegionData;
292 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
293 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
294 const RegionData* c = summary_data.region(end_region - 1);
295 HeapWord* end_addr = c->destination() + c->data_size();
296 const size_t live_in_space = pointer_delta(end_addr, space->bottom());
297
298 // Print (and count) the full regions at the beginning of the space.
299 size_t full_region_count = 0;
300 size_t i = summary_data.addr_to_region_idx(space->bottom());
301 while (i < end_region && summary_data.region(i)->data_size() == region_size) {
302 print_initial_summary_region(i, summary_data.region(i));
303 ++full_region_count;
304 ++i;
305 }
306
307 size_t live_to_right = live_in_space - full_region_count * region_size;
308
309 double max_reclaimed_ratio = 0.0;
310 size_t max_reclaimed_ratio_region = 0;
311 size_t max_dead_to_right = 0;
312 size_t max_live_to_right = 0;
313
314 // Print the 'reclaimed ratio' for regions while there is something live in
315 // the region or to the right of it. The remaining regions are empty (and
316 // uninteresting), and computing the ratio will result in division by 0.
317 while (i < end_region && live_to_right > 0) {
318 c = summary_data.region(i);
319 HeapWord* const region_addr = summary_data.region_to_addr(i);
320 const size_t used_to_right = pointer_delta(space->top(), region_addr);
321 const size_t dead_to_right = used_to_right - live_to_right;
322 const double reclaimed_ratio = double(dead_to_right) / live_to_right;
323
324 if (reclaimed_ratio > max_reclaimed_ratio) {
325 max_reclaimed_ratio = reclaimed_ratio;
326 max_reclaimed_ratio_region = i;
327 max_dead_to_right = dead_to_right;
328 max_live_to_right = live_to_right;
329 }
330
331 print_initial_summary_region(i, c, false);
332 tty->print_cr(" %12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
333 reclaimed_ratio, dead_to_right, live_to_right);
334
335 live_to_right -= c->data_size();
336 ++i;
337 }
338
339 // Any remaining regions are empty. Print one more if there is one.
340 if (i < end_region) {
341 print_initial_summary_region(i, summary_data.region(i));
342 }
343
344 tty->print_cr("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " "
345 "l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
346 max_reclaimed_ratio_region, max_dead_to_right,
347 max_live_to_right, max_reclaimed_ratio);
348 }
349
350 void
351 print_initial_summary_data(ParallelCompactData& summary_data,
352 SpaceInfo* space_info) {
353 unsigned int id = PSParallelCompact::old_space_id;
354 const MutableSpace* space;
355 do {
356 space = space_info[id].space();
357 print_initial_summary_data(summary_data, space);
358 } while (++id < PSParallelCompact::eden_space_id);
359
360 do {
361 space = space_info[id].space();
362 print_generic_summary_data(summary_data, space->bottom(), space->top());
363 } while (++id < PSParallelCompact::last_space_id);
364 }
365 #endif // #ifndef PRODUCT
366
367 #ifdef ASSERT
368 size_t add_obj_count;
369 size_t add_obj_size;
370 size_t mark_bitmap_count;
371 size_t mark_bitmap_size;
372 #endif // #ifdef ASSERT
373
374 ParallelCompactData::ParallelCompactData()
375 {
376 _region_start = 0;
377
378 _region_vspace = 0;
379 _reserved_byte_size = 0;
380 _region_data = 0;
381 _region_count = 0;
382
383 _block_vspace = 0;
384 _block_data = 0;
385 _block_count = 0;
386 }
387
388 bool ParallelCompactData::initialize(MemRegion covered_region)
389 {
390 _region_start = covered_region.start();
391 const size_t region_size = covered_region.word_size();
392 DEBUG_ONLY(_region_end = _region_start + region_size;)
393
394 assert(region_align_down(_region_start) == _region_start,
395 "region start not aligned");
396 assert((region_size & RegionSizeOffsetMask) == 0,
397 "region size not a multiple of RegionSize");
398
399 bool result = initialize_region_data(region_size) && initialize_block_data();
400 return result;
401 }
402
403 PSVirtualSpace*
404 ParallelCompactData::create_vspace(size_t count, size_t element_size)
405 {
406 const size_t raw_bytes = count * element_size;
407 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
408 const size_t granularity = os::vm_allocation_granularity();
409 _reserved_byte_size = align_size_up(raw_bytes, MAX2(page_sz, granularity));
410
411 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
412 MAX2(page_sz, granularity);
413 ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0);
414 os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(),
415 rs.size());
416
417 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
418
419 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
420 if (vspace != 0) {
421 if (vspace->expand_by(_reserved_byte_size)) {
422 return vspace;
423 }
424 delete vspace;
425 // Release memory reserved in the space.
426 rs.release();
427 }
428
429 return 0;
430 }
431
432 bool ParallelCompactData::initialize_region_data(size_t region_size)
433 {
434 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
435 _region_vspace = create_vspace(count, sizeof(RegionData));
436 if (_region_vspace != 0) {
437 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
438 _region_count = count;
439 return true;
440 }
441 return false;
442 }
443
444 bool ParallelCompactData::initialize_block_data()
445 {
446 assert(_region_count != 0, "region data must be initialized first");
447 const size_t count = _region_count << Log2BlocksPerRegion;
448 _block_vspace = create_vspace(count, sizeof(BlockData));
449 if (_block_vspace != 0) {
450 _block_data = (BlockData*)_block_vspace->reserved_low_addr();
451 _block_count = count;
452 return true;
453 }
454 return false;
455 }
456
457 void ParallelCompactData::clear()
458 {
459 memset(_region_data, 0, _region_vspace->committed_size());
460 memset(_block_data, 0, _block_vspace->committed_size());
461 }
462
463 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
464 assert(beg_region <= _region_count, "beg_region out of range");
465 assert(end_region <= _region_count, "end_region out of range");
466 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize");
467
468 const size_t region_cnt = end_region - beg_region;
469 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
470
471 const size_t beg_block = beg_region * BlocksPerRegion;
472 const size_t block_cnt = region_cnt * BlocksPerRegion;
473 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));
474 }
475
476 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
477 {
478 const RegionData* cur_cp = region(region_idx);
479 const RegionData* const end_cp = region(region_count() - 1);
480
481 HeapWord* result = region_to_addr(region_idx);
482 if (cur_cp < end_cp) {
483 do {
484 result += cur_cp->partial_obj_size();
485 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
486 }
487 return result;
488 }
489
490 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
491 {
492 const size_t obj_ofs = pointer_delta(addr, _region_start);
493 const size_t beg_region = obj_ofs >> Log2RegionSize;
494 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
495
496 DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
497 DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
498
499 if (beg_region == end_region) {
500 // All in one region.
501 _region_data[beg_region].add_live_obj(len);
502 return;
503 }
504
505 // First region.
506 const size_t beg_ofs = region_offset(addr);
507 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
508
509 Klass* klass = ((oop)addr)->klass();
510 // Middle regions--completely spanned by this object.
511 for (size_t region = beg_region + 1; region < end_region; ++region) {
512 _region_data[region].set_partial_obj_size(RegionSize);
513 _region_data[region].set_partial_obj_addr(addr);
514 }
515
516 // Last region.
517 const size_t end_ofs = region_offset(addr + len - 1);
518 _region_data[end_region].set_partial_obj_size(end_ofs + 1);
519 _region_data[end_region].set_partial_obj_addr(addr);
520 }
521
522 void
523 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
524 {
525 assert(region_offset(beg) == 0, "not RegionSize aligned");
526 assert(region_offset(end) == 0, "not RegionSize aligned");
527
528 size_t cur_region = addr_to_region_idx(beg);
529 const size_t end_region = addr_to_region_idx(end);
530 HeapWord* addr = beg;
531 while (cur_region < end_region) {
532 _region_data[cur_region].set_destination(addr);
533 _region_data[cur_region].set_destination_count(0);
534 _region_data[cur_region].set_source_region(cur_region);
535 _region_data[cur_region].set_data_location(addr);
536
537 // Update live_obj_size so the region appears completely full.
538 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
539 _region_data[cur_region].set_live_obj_size(live_size);
540
541 ++cur_region;
542 addr += RegionSize;
543 }
544 }
545
546 // Find the point at which a space can be split and, if necessary, record the
547 // split point.
548 //
549 // If the current src region (which overflowed the destination space) doesn't
550 // have a partial object, the split point is at the beginning of the current src
551 // region (an "easy" split, no extra bookkeeping required).
552 //
553 // If the current src region has a partial object, the split point is in the
554 // region where that partial object starts (call it the split_region). If
555 // split_region has a partial object, then the split point is just after that
556 // partial object (a "hard" split where we have to record the split data and
557 // zero the partial_obj_size field). With a "hard" split, we know that the
558 // partial_obj ends within split_region because the partial object that caused
559 // the overflow starts in split_region. If split_region doesn't have a partial
560 // obj, then the split is at the beginning of split_region (another "easy"
561 // split).
562 HeapWord*
563 ParallelCompactData::summarize_split_space(size_t src_region,
564 SplitInfo& split_info,
565 HeapWord* destination,
566 HeapWord* target_end,
567 HeapWord** target_next)
568 {
569 assert(destination <= target_end, "sanity");
570 assert(destination + _region_data[src_region].data_size() > target_end,
571 "region should not fit into target space");
572 assert(is_region_aligned(target_end), "sanity");
573
574 size_t split_region = src_region;
575 HeapWord* split_destination = destination;
576 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
577
578 if (destination + partial_obj_size > target_end) {
579 // The split point is just after the partial object (if any) in the
580 // src_region that contains the start of the object that overflowed the
581 // destination space.
582 //
583 // Find the start of the "overflow" object and set split_region to the
584 // region containing it.
585 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
586 split_region = addr_to_region_idx(overflow_obj);
587
588 // Clear the source_region field of all destination regions whose first word
589 // came from data after the split point (a non-null source_region field
590 // implies a region must be filled).
591 //
592 // An alternative to the simple loop below: clear during post_compact(),
593 // which uses memcpy instead of individual stores, and is easy to
594 // parallelize. (The downside is that it clears the entire RegionData
595 // object as opposed to just one field.)
596 //
597 // post_compact() would have to clear the summary data up to the highest
598 // address that was written during the summary phase, which would be
599 //
600 // max(top, max(new_top, clear_top))
601 //
602 // where clear_top is a new field in SpaceInfo. Would have to set clear_top
603 // to target_end.
604 const RegionData* const sr = region(split_region);
605 const size_t beg_idx =
606 addr_to_region_idx(region_align_up(sr->destination() +
607 sr->partial_obj_size()));
608 const size_t end_idx = addr_to_region_idx(target_end);
609
610 if (TraceParallelOldGCSummaryPhase) {
611 gclog_or_tty->print_cr("split: clearing source_region field in ["
612 SIZE_FORMAT ", " SIZE_FORMAT ")",
613 beg_idx, end_idx);
614 }
615 for (size_t idx = beg_idx; idx < end_idx; ++idx) {
616 _region_data[idx].set_source_region(0);
617 }
618
619 // Set split_destination and partial_obj_size to reflect the split region.
620 split_destination = sr->destination();
621 partial_obj_size = sr->partial_obj_size();
622 }
623
624 // The split is recorded only if a partial object extends onto the region.
625 if (partial_obj_size != 0) {
626 _region_data[split_region].set_partial_obj_size(0);
627 split_info.record(split_region, partial_obj_size, split_destination);
628 }
629
630 // Setup the continuation addresses.
631 *target_next = split_destination + partial_obj_size;
632 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
633
634 if (TraceParallelOldGCSummaryPhase) {
635 const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
636 gclog_or_tty->print_cr("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT
637 " pos=" SIZE_FORMAT,
638 split_type, p2i(source_next), split_region,
639 partial_obj_size);
640 gclog_or_tty->print_cr("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT
641 " tn=" PTR_FORMAT,
642 split_type, p2i(split_destination),
643 addr_to_region_idx(split_destination),
644 p2i(*target_next));
645
646 if (partial_obj_size != 0) {
647 HeapWord* const po_beg = split_info.destination();
648 HeapWord* const po_end = po_beg + split_info.partial_obj_size();
649 gclog_or_tty->print_cr("%s split: "
650 "po_beg=" PTR_FORMAT " " SIZE_FORMAT " "
651 "po_end=" PTR_FORMAT " " SIZE_FORMAT,
652 split_type,
653 p2i(po_beg), addr_to_region_idx(po_beg),
654 p2i(po_end), addr_to_region_idx(po_end));
655 }
656 }
657
658 return source_next;
659 }
660
661 bool ParallelCompactData::summarize(SplitInfo& split_info,
662 HeapWord* source_beg, HeapWord* source_end,
663 HeapWord** source_next,
664 HeapWord* target_beg, HeapWord* target_end,
665 HeapWord** target_next)
666 {
667 if (TraceParallelOldGCSummaryPhase) {
668 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
669 tty->print_cr("sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
670 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
671 p2i(source_beg), p2i(source_end), p2i(source_next_val),
672 p2i(target_beg), p2i(target_end), p2i(*target_next));
673 }
674
675 size_t cur_region = addr_to_region_idx(source_beg);
676 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
677
678 HeapWord *dest_addr = target_beg;
679 while (cur_region < end_region) {
680 // The destination must be set even if the region has no data.
681 _region_data[cur_region].set_destination(dest_addr);
682
683 size_t words = _region_data[cur_region].data_size();
684 if (words > 0) {
685 // If cur_region does not fit entirely into the target space, find a point
686 // at which the source space can be 'split' so that part is copied to the
687 // target space and the rest is copied elsewhere.
688 if (dest_addr + words > target_end) {
689 assert(source_next != NULL, "source_next is NULL when splitting");
690 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
691 target_end, target_next);
692 return false;
693 }
694
695 // Compute the destination_count for cur_region, and if necessary, update
696 // source_region for a destination region. The source_region field is
697 // updated if cur_region is the first (left-most) region to be copied to a
698 // destination region.
699 //
700 // The destination_count calculation is a bit subtle. A region that has
701 // data that compacts into itself does not count itself as a destination.
702 // This maintains the invariant that a zero count means the region is
703 // available and can be claimed and then filled.
704 uint destination_count = 0;
705 if (split_info.is_split(cur_region)) {
706 // The current region has been split: the partial object will be copied
707 // to one destination space and the remaining data will be copied to
708 // another destination space. Adjust the initial destination_count and,
709 // if necessary, set the source_region field if the partial object will
710 // cross a destination region boundary.
711 destination_count = split_info.destination_count();
712 if (destination_count == 2) {
713 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
714 _region_data[dest_idx].set_source_region(cur_region);
715 }
716 }
717
718 HeapWord* const last_addr = dest_addr + words - 1;
719 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
720 const size_t dest_region_2 = addr_to_region_idx(last_addr);
721
722 // Initially assume that the destination regions will be the same and
723 // adjust the value below if necessary. Under this assumption, if
724 // cur_region == dest_region_2, then cur_region will be compacted
725 // completely into itself.
726 destination_count += cur_region == dest_region_2 ? 0 : 1;
727 if (dest_region_1 != dest_region_2) {
728 // Destination regions differ; adjust destination_count.
729 destination_count += 1;
730 // Data from cur_region will be copied to the start of dest_region_2.
731 _region_data[dest_region_2].set_source_region(cur_region);
732 } else if (region_offset(dest_addr) == 0) {
733 // Data from cur_region will be copied to the start of the destination
734 // region.
735 _region_data[dest_region_1].set_source_region(cur_region);
736 }
737
738 _region_data[cur_region].set_destination_count(destination_count);
739 _region_data[cur_region].set_data_location(region_to_addr(cur_region));
740 dest_addr += words;
741 }
742
743 ++cur_region;
744 }
745
746 *target_next = dest_addr;
747 return true;
748 }
749
750 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) {
751 assert(addr != NULL, "Should detect NULL oop earlier");
752 assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap");
753 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked");
754
755 // Region covering the object.
756 RegionData* const region_ptr = addr_to_region_ptr(addr);
757 HeapWord* result = region_ptr->destination();
758
759 // If the entire Region is live, the new location is region->destination + the
760 // offset of the object within in the Region.
761
762 // Run some performance tests to determine if this special case pays off. It
763 // is worth it for pointers into the dense prefix. If the optimization to
764 // avoid pointer updates in regions that only point to the dense prefix is
765 // ever implemented, this should be revisited.
766 if (region_ptr->data_size() == RegionSize) {
767 result += region_offset(addr);
768 return result;
769 }
770
771 // Otherwise, the new location is region->destination + block offset + the
772 // number of live words in the Block that are (a) to the left of addr and (b)
773 // due to objects that start in the Block.
774
775 // Fill in the block table if necessary. This is unsynchronized, so multiple
776 // threads may fill the block table for a region (harmless, since it is
777 // idempotent).
778 if (!region_ptr->blocks_filled()) {
779 PSParallelCompact::fill_blocks(addr_to_region_idx(addr));
780 region_ptr->set_blocks_filled();
781 }
782
783 HeapWord* const search_start = block_align_down(addr);
784 const size_t block_offset = addr_to_block_ptr(addr)->offset();
785
786 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
787 const size_t live = bitmap->live_words_in_range(search_start, oop(addr));
788 result += block_offset + live;
789 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result));
790 return result;
791 }
792
793 #ifdef ASSERT
794 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
795 {
796 const size_t* const beg = (const size_t*)vspace->committed_low_addr();
797 const size_t* const end = (const size_t*)vspace->committed_high_addr();
798 for (const size_t* p = beg; p < end; ++p) {
799 assert(*p == 0, "not zero");
800 }
801 }
802
803 void ParallelCompactData::verify_clear()
804 {
805 verify_clear(_region_vspace);
806 verify_clear(_block_vspace);
807 }
808 #endif // #ifdef ASSERT
809
810 STWGCTimer PSParallelCompact::_gc_timer;
811 ParallelOldTracer PSParallelCompact::_gc_tracer;
812 elapsedTimer PSParallelCompact::_accumulated_time;
813 unsigned int PSParallelCompact::_total_invocations = 0;
814 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
815 jlong PSParallelCompact::_time_of_last_gc = 0;
816 CollectorCounters* PSParallelCompact::_counters = NULL;
817 ParMarkBitMap PSParallelCompact::_mark_bitmap;
818 ParallelCompactData PSParallelCompact::_summary_data;
819
820 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
821
822 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
823
824 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_pointer_closure;
825 PSParallelCompact::AdjustKlassClosure PSParallelCompact::_adjust_klass_closure;
826
827 void PSParallelCompact::AdjustKlassClosure::do_klass(Klass* klass) {
828 klass->oops_do(&PSParallelCompact::_adjust_pointer_closure);
829 }
830
831 void PSParallelCompact::post_initialize() {
832 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
833 MemRegion mr = heap->reserved_region();
834 _ref_processor =
835 new ReferenceProcessor(mr, // span
836 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
837 ParallelGCThreads, // mt processing degree
838 true, // mt discovery
839 ParallelGCThreads, // mt discovery degree
840 true, // atomic_discovery
841 &_is_alive_closure); // non-header is alive closure
842 _counters = new CollectorCounters("PSParallelCompact", 1);
843
844 // Initialize static fields in ParCompactionManager.
845 ParCompactionManager::initialize(mark_bitmap());
846 }
847
848 bool PSParallelCompact::initialize() {
849 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
850 MemRegion mr = heap->reserved_region();
851
852 // Was the old gen get allocated successfully?
853 if (!heap->old_gen()->is_allocated()) {
854 return false;
855 }
856
857 initialize_space_info();
858 initialize_dead_wood_limiter();
859
860 if (!_mark_bitmap.initialize(mr)) {
861 vm_shutdown_during_initialization(
862 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
863 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
864 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
865 return false;
866 }
867
868 if (!_summary_data.initialize(mr)) {
869 vm_shutdown_during_initialization(
870 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
871 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
872 _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
873 return false;
874 }
875
876 return true;
877 }
878
879 void PSParallelCompact::initialize_space_info()
880 {
881 memset(&_space_info, 0, sizeof(_space_info));
882
883 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
884 PSYoungGen* young_gen = heap->young_gen();
885
886 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
887 _space_info[eden_space_id].set_space(young_gen->eden_space());
888 _space_info[from_space_id].set_space(young_gen->from_space());
889 _space_info[to_space_id].set_space(young_gen->to_space());
890
891 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
892 }
893
894 void PSParallelCompact::initialize_dead_wood_limiter()
895 {
896 const size_t max = 100;
897 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
898 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
899 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
900 DEBUG_ONLY(_dwl_initialized = true;)
901 _dwl_adjustment = normal_distribution(1.0);
902 }
903
904 // Simple class for storing info about the heap at the start of GC, to be used
905 // after GC for comparison/printing.
906 class PreGCValues {
907 public:
908 PreGCValues() { }
909 PreGCValues(ParallelScavengeHeap* heap) { fill(heap); }
910
911 void fill(ParallelScavengeHeap* heap) {
912 _heap_used = heap->used();
913 _young_gen_used = heap->young_gen()->used_in_bytes();
914 _old_gen_used = heap->old_gen()->used_in_bytes();
915 _metadata_used = MetaspaceAux::used_bytes();
916 };
917
918 size_t heap_used() const { return _heap_used; }
919 size_t young_gen_used() const { return _young_gen_used; }
920 size_t old_gen_used() const { return _old_gen_used; }
921 size_t metadata_used() const { return _metadata_used; }
922
923 private:
924 size_t _heap_used;
925 size_t _young_gen_used;
926 size_t _old_gen_used;
927 size_t _metadata_used;
928 };
929
930 void
931 PSParallelCompact::clear_data_covering_space(SpaceId id)
932 {
933 // At this point, top is the value before GC, new_top() is the value that will
934 // be set at the end of GC. The marking bitmap is cleared to top; nothing
935 // should be marked above top. The summary data is cleared to the larger of
936 // top & new_top.
937 MutableSpace* const space = _space_info[id].space();
938 HeapWord* const bot = space->bottom();
939 HeapWord* const top = space->top();
940 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
941
942 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
943 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
944 _mark_bitmap.clear_range(beg_bit, end_bit);
945
946 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
947 const size_t end_region =
948 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
949 _summary_data.clear_range(beg_region, end_region);
950
951 // Clear the data used to 'split' regions.
952 SplitInfo& split_info = _space_info[id].split_info();
953 if (split_info.is_valid()) {
954 split_info.clear();
955 }
956 DEBUG_ONLY(split_info.verify_clear();)
957 }
958
959 void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values)
960 {
961 // Update the from & to space pointers in space_info, since they are swapped
962 // at each young gen gc. Do the update unconditionally (even though a
963 // promotion failure does not swap spaces) because an unknown number of young
964 // collections will have swapped the spaces an unknown number of times.
965 GCTraceTime tm("pre compact", print_phases(), true, &_gc_timer);
966 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
967 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
968 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
969
970 pre_gc_values->fill(heap);
971
972 DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
973 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
974
975 // Increment the invocation count
976 heap->increment_total_collections(true);
977
978 // We need to track unique mark sweep invocations as well.
979 _total_invocations++;
980
981 heap->print_heap_before_gc();
982 heap->trace_heap_before_gc(&_gc_tracer);
983
984 // Fill in TLABs
985 heap->accumulate_statistics_all_tlabs();
986 heap->ensure_parsability(true); // retire TLABs
987
988 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
989 HandleMark hm; // Discard invalid handles created during verification
990 Universe::verify(" VerifyBeforeGC:");
991 }
992
993 // Verify object start arrays
994 if (VerifyObjectStartArray &&
995 VerifyBeforeGC) {
996 heap->old_gen()->verify_object_start_array();
997 }
998
999 DEBUG_ONLY(mark_bitmap()->verify_clear();)
1000 DEBUG_ONLY(summary_data().verify_clear();)
1001
1002 // Have worker threads release resources the next time they run a task.
1003 gc_task_manager()->release_all_resources();
1004 }
1005
1006 void PSParallelCompact::post_compact()
1007 {
1008 GCTraceTime tm("post compact", print_phases(), true, &_gc_timer);
1009
1010 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1011 // Clear the marking bitmap, summary data and split info.
1012 clear_data_covering_space(SpaceId(id));
1013 // Update top(). Must be done after clearing the bitmap and summary data.
1014 _space_info[id].publish_new_top();
1015 }
1016
1017 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1018 MutableSpace* const from_space = _space_info[from_space_id].space();
1019 MutableSpace* const to_space = _space_info[to_space_id].space();
1020
1021 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1022 bool eden_empty = eden_space->is_empty();
1023 if (!eden_empty) {
1024 eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1025 heap->young_gen(), heap->old_gen());
1026 }
1027
1028 // Update heap occupancy information which is used as input to the soft ref
1029 // clearing policy at the next gc.
1030 Universe::update_heap_info_at_gc();
1031
1032 bool young_gen_empty = eden_empty && from_space->is_empty() &&
1033 to_space->is_empty();
1034
1035 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set());
1036 MemRegion old_mr = heap->old_gen()->reserved();
1037 if (young_gen_empty) {
1038 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
1039 } else {
1040 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1041 }
1042
1043 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1044 ClassLoaderDataGraph::purge();
1045 MetaspaceAux::verify_metrics();
1046
1047 CodeCache::gc_epilogue();
1048 JvmtiExport::gc_epilogue();
1049
1050 #if defined(COMPILER2) || INCLUDE_JVMCI
1051 DerivedPointerTable::update_pointers();
1052 #endif
1053
1054 ref_processor()->enqueue_discovered_references(NULL);
1055
1056 if (ZapUnusedHeapArea) {
1057 heap->gen_mangle_unused_area();
1058 }
1059
1060 // Update time of last GC
1061 reset_millis_since_last_gc();
1062 }
1063
1064 HeapWord*
1065 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1066 bool maximum_compaction)
1067 {
1068 const size_t region_size = ParallelCompactData::RegionSize;
1069 const ParallelCompactData& sd = summary_data();
1070
1071 const MutableSpace* const space = _space_info[id].space();
1072 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1073 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1074 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1075
1076 // Skip full regions at the beginning of the space--they are necessarily part
1077 // of the dense prefix.
1078 size_t full_count = 0;
1079 const RegionData* cp;
1080 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1081 ++full_count;
1082 }
1083
1084 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1085 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1086 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1087 if (maximum_compaction || cp == end_cp || interval_ended) {
1088 _maximum_compaction_gc_num = total_invocations();
1089 return sd.region_to_addr(cp);
1090 }
1091
1092 HeapWord* const new_top = _space_info[id].new_top();
1093 const size_t space_live = pointer_delta(new_top, space->bottom());
1094 const size_t space_used = space->used_in_words();
1095 const size_t space_capacity = space->capacity_in_words();
1096
1097 const double cur_density = double(space_live) / space_capacity;
1098 const double deadwood_density =
1099 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1100 const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1101
1102 if (TraceParallelOldGCDensePrefix) {
1103 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1104 cur_density, deadwood_density, deadwood_goal);
1105 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1106 "space_cap=" SIZE_FORMAT,
1107 space_live, space_used,
1108 space_capacity);
1109 }
1110
1111 // XXX - Use binary search?
1112 HeapWord* dense_prefix = sd.region_to_addr(cp);
1113 const RegionData* full_cp = cp;
1114 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1115 while (cp < end_cp) {
1116 HeapWord* region_destination = cp->destination();
1117 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1118 if (TraceParallelOldGCDensePrefix && Verbose) {
1119 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1120 "dp=" PTR_FORMAT " " "cdw=" SIZE_FORMAT_W(8),
1121 sd.region(cp), p2i(region_destination),
1122 p2i(dense_prefix), cur_deadwood);
1123 }
1124
1125 if (cur_deadwood >= deadwood_goal) {
1126 // Found the region that has the correct amount of deadwood to the left.
1127 // This typically occurs after crossing a fairly sparse set of regions, so
1128 // iterate backwards over those sparse regions, looking for the region
1129 // that has the lowest density of live objects 'to the right.'
1130 size_t space_to_left = sd.region(cp) * region_size;
1131 size_t live_to_left = space_to_left - cur_deadwood;
1132 size_t space_to_right = space_capacity - space_to_left;
1133 size_t live_to_right = space_live - live_to_left;
1134 double density_to_right = double(live_to_right) / space_to_right;
1135 while (cp > full_cp) {
1136 --cp;
1137 const size_t prev_region_live_to_right = live_to_right -
1138 cp->data_size();
1139 const size_t prev_region_space_to_right = space_to_right + region_size;
1140 double prev_region_density_to_right =
1141 double(prev_region_live_to_right) / prev_region_space_to_right;
1142 if (density_to_right <= prev_region_density_to_right) {
1143 return dense_prefix;
1144 }
1145 if (TraceParallelOldGCDensePrefix && Verbose) {
1146 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1147 "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1148 prev_region_density_to_right);
1149 }
1150 dense_prefix -= region_size;
1151 live_to_right = prev_region_live_to_right;
1152 space_to_right = prev_region_space_to_right;
1153 density_to_right = prev_region_density_to_right;
1154 }
1155 return dense_prefix;
1156 }
1157
1158 dense_prefix += region_size;
1159 ++cp;
1160 }
1161
1162 return dense_prefix;
1163 }
1164
1165 #ifndef PRODUCT
1166 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1167 const SpaceId id,
1168 const bool maximum_compaction,
1169 HeapWord* const addr)
1170 {
1171 const size_t region_idx = summary_data().addr_to_region_idx(addr);
1172 RegionData* const cp = summary_data().region(region_idx);
1173 const MutableSpace* const space = _space_info[id].space();
1174 HeapWord* const new_top = _space_info[id].new_top();
1175
1176 const size_t space_live = pointer_delta(new_top, space->bottom());
1177 const size_t dead_to_left = pointer_delta(addr, cp->destination());
1178 const size_t space_cap = space->capacity_in_words();
1179 const double dead_to_left_pct = double(dead_to_left) / space_cap;
1180 const size_t live_to_right = new_top - cp->destination();
1181 const size_t dead_to_right = space->top() - addr - live_to_right;
1182
1183 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1184 "spl=" SIZE_FORMAT " "
1185 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1186 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1187 " ratio=%10.8f",
1188 algorithm, p2i(addr), region_idx,
1189 space_live,
1190 dead_to_left, dead_to_left_pct,
1191 dead_to_right, live_to_right,
1192 double(dead_to_right) / live_to_right);
1193 }
1194 #endif // #ifndef PRODUCT
1195
1196 // Return a fraction indicating how much of the generation can be treated as
1197 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution
1198 // based on the density of live objects in the generation to determine a limit,
1199 // which is then adjusted so the return value is min_percent when the density is
1200 // 1.
1201 //
1202 // The following table shows some return values for a different values of the
1203 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1204 // min_percent is 1.
1205 //
1206 // fraction allowed as dead wood
1207 // -----------------------------------------------------------------
1208 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1209 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1210 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1211 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1212 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1213 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1214 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1215 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1216 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1217 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1218 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1219 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1220 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1221 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1222 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1223 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1224 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1225 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1226 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1227 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1228 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1229 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1230 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1231
1232 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1233 {
1234 assert(_dwl_initialized, "uninitialized");
1235
1236 // The raw limit is the value of the normal distribution at x = density.
1237 const double raw_limit = normal_distribution(density);
1238
1239 // Adjust the raw limit so it becomes the minimum when the density is 1.
1240 //
1241 // First subtract the adjustment value (which is simply the precomputed value
1242 // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1243 // Then add the minimum value, so the minimum is returned when the density is
1244 // 1. Finally, prevent negative values, which occur when the mean is not 0.5.
1245 const double min = double(min_percent) / 100.0;
1246 const double limit = raw_limit - _dwl_adjustment + min;
1247 return MAX2(limit, 0.0);
1248 }
1249
1250 ParallelCompactData::RegionData*
1251 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1252 const RegionData* end)
1253 {
1254 const size_t region_size = ParallelCompactData::RegionSize;
1255 ParallelCompactData& sd = summary_data();
1256 size_t left = sd.region(beg);
1257 size_t right = end > beg ? sd.region(end) - 1 : left;
1258
1259 // Binary search.
1260 while (left < right) {
1261 // Equivalent to (left + right) / 2, but does not overflow.
1262 const size_t middle = left + (right - left) / 2;
1263 RegionData* const middle_ptr = sd.region(middle);
1264 HeapWord* const dest = middle_ptr->destination();
1265 HeapWord* const addr = sd.region_to_addr(middle);
1266 assert(dest != NULL, "sanity");
1267 assert(dest <= addr, "must move left");
1268
1269 if (middle > left && dest < addr) {
1270 right = middle - 1;
1271 } else if (middle < right && middle_ptr->data_size() == region_size) {
1272 left = middle + 1;
1273 } else {
1274 return middle_ptr;
1275 }
1276 }
1277 return sd.region(left);
1278 }
1279
1280 ParallelCompactData::RegionData*
1281 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1282 const RegionData* end,
1283 size_t dead_words)
1284 {
1285 ParallelCompactData& sd = summary_data();
1286 size_t left = sd.region(beg);
1287 size_t right = end > beg ? sd.region(end) - 1 : left;
1288
1289 // Binary search.
1290 while (left < right) {
1291 // Equivalent to (left + right) / 2, but does not overflow.
1292 const size_t middle = left + (right - left) / 2;
1293 RegionData* const middle_ptr = sd.region(middle);
1294 HeapWord* const dest = middle_ptr->destination();
1295 HeapWord* const addr = sd.region_to_addr(middle);
1296 assert(dest != NULL, "sanity");
1297 assert(dest <= addr, "must move left");
1298
1299 const size_t dead_to_left = pointer_delta(addr, dest);
1300 if (middle > left && dead_to_left > dead_words) {
1301 right = middle - 1;
1302 } else if (middle < right && dead_to_left < dead_words) {
1303 left = middle + 1;
1304 } else {
1305 return middle_ptr;
1306 }
1307 }
1308 return sd.region(left);
1309 }
1310
1311 // The result is valid during the summary phase, after the initial summarization
1312 // of each space into itself, and before final summarization.
1313 inline double
1314 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1315 HeapWord* const bottom,
1316 HeapWord* const top,
1317 HeapWord* const new_top)
1318 {
1319 ParallelCompactData& sd = summary_data();
1320
1321 assert(cp != NULL, "sanity");
1322 assert(bottom != NULL, "sanity");
1323 assert(top != NULL, "sanity");
1324 assert(new_top != NULL, "sanity");
1325 assert(top >= new_top, "summary data problem?");
1326 assert(new_top > bottom, "space is empty; should not be here");
1327 assert(new_top >= cp->destination(), "sanity");
1328 assert(top >= sd.region_to_addr(cp), "sanity");
1329
1330 HeapWord* const destination = cp->destination();
1331 const size_t dense_prefix_live = pointer_delta(destination, bottom);
1332 const size_t compacted_region_live = pointer_delta(new_top, destination);
1333 const size_t compacted_region_used = pointer_delta(top,
1334 sd.region_to_addr(cp));
1335 const size_t reclaimable = compacted_region_used - compacted_region_live;
1336
1337 const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1338 return double(reclaimable) / divisor;
1339 }
1340
1341 // Return the address of the end of the dense prefix, a.k.a. the start of the
1342 // compacted region. The address is always on a region boundary.
1343 //
1344 // Completely full regions at the left are skipped, since no compaction can
1345 // occur in those regions. Then the maximum amount of dead wood to allow is
1346 // computed, based on the density (amount live / capacity) of the generation;
1347 // the region with approximately that amount of dead space to the left is
1348 // identified as the limit region. Regions between the last completely full
1349 // region and the limit region are scanned and the one that has the best
1350 // (maximum) reclaimed_ratio() is selected.
1351 HeapWord*
1352 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1353 bool maximum_compaction)
1354 {
1355 const size_t region_size = ParallelCompactData::RegionSize;
1356 const ParallelCompactData& sd = summary_data();
1357
1358 const MutableSpace* const space = _space_info[id].space();
1359 HeapWord* const top = space->top();
1360 HeapWord* const top_aligned_up = sd.region_align_up(top);
1361 HeapWord* const new_top = _space_info[id].new_top();
1362 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1363 HeapWord* const bottom = space->bottom();
1364 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1365 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1366 const RegionData* const new_top_cp =
1367 sd.addr_to_region_ptr(new_top_aligned_up);
1368
1369 // Skip full regions at the beginning of the space--they are necessarily part
1370 // of the dense prefix.
1371 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1372 assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1373 space->is_empty(), "no dead space allowed to the left");
1374 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1375 "region must have dead space");
1376
1377 // The gc number is saved whenever a maximum compaction is done, and used to
1378 // determine when the maximum compaction interval has expired. This avoids
1379 // successive max compactions for different reasons.
1380 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1381 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1382 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1383 total_invocations() == HeapFirstMaximumCompactionCount;
1384 if (maximum_compaction || full_cp == top_cp || interval_ended) {
1385 _maximum_compaction_gc_num = total_invocations();
1386 return sd.region_to_addr(full_cp);
1387 }
1388
1389 const size_t space_live = pointer_delta(new_top, bottom);
1390 const size_t space_used = space->used_in_words();
1391 const size_t space_capacity = space->capacity_in_words();
1392
1393 const double density = double(space_live) / double(space_capacity);
1394 const size_t min_percent_free = MarkSweepDeadRatio;
1395 const double limiter = dead_wood_limiter(density, min_percent_free);
1396 const size_t dead_wood_max = space_used - space_live;
1397 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1398 dead_wood_max);
1399
1400 if (TraceParallelOldGCDensePrefix) {
1401 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1402 "space_cap=" SIZE_FORMAT,
1403 space_live, space_used,
1404 space_capacity);
1405 tty->print_cr("dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f "
1406 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1407 density, min_percent_free, limiter,
1408 dead_wood_max, dead_wood_limit);
1409 }
1410
1411 // Locate the region with the desired amount of dead space to the left.
1412 const RegionData* const limit_cp =
1413 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1414
1415 // Scan from the first region with dead space to the limit region and find the
1416 // one with the best (largest) reclaimed ratio.
1417 double best_ratio = 0.0;
1418 const RegionData* best_cp = full_cp;
1419 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1420 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1421 if (tmp_ratio > best_ratio) {
1422 best_cp = cp;
1423 best_ratio = tmp_ratio;
1424 }
1425 }
1426
1427 return sd.region_to_addr(best_cp);
1428 }
1429
1430 void PSParallelCompact::summarize_spaces_quick()
1431 {
1432 for (unsigned int i = 0; i < last_space_id; ++i) {
1433 const MutableSpace* space = _space_info[i].space();
1434 HeapWord** nta = _space_info[i].new_top_addr();
1435 bool result = _summary_data.summarize(_space_info[i].split_info(),
1436 space->bottom(), space->top(), NULL,
1437 space->bottom(), space->end(), nta);
1438 assert(result, "space must fit into itself");
1439 _space_info[i].set_dense_prefix(space->bottom());
1440 }
1441 }
1442
1443 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1444 {
1445 HeapWord* const dense_prefix_end = dense_prefix(id);
1446 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1447 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1448 if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1449 // Only enough dead space is filled so that any remaining dead space to the
1450 // left is larger than the minimum filler object. (The remainder is filled
1451 // during the copy/update phase.)
1452 //
1453 // The size of the dead space to the right of the boundary is not a
1454 // concern, since compaction will be able to use whatever space is
1455 // available.
1456 //
1457 // Here '||' is the boundary, 'x' represents a don't care bit and a box
1458 // surrounds the space to be filled with an object.
1459 //
1460 // In the 32-bit VM, each bit represents two 32-bit words:
1461 // +---+
1462 // a) beg_bits: ... x x x | 0 | || 0 x x ...
1463 // end_bits: ... x x x | 0 | || 0 x x ...
1464 // +---+
1465 //
1466 // In the 64-bit VM, each bit represents one 64-bit word:
1467 // +------------+
1468 // b) beg_bits: ... x x x | 0 || 0 | x x ...
1469 // end_bits: ... x x 1 | 0 || 0 | x x ...
1470 // +------------+
1471 // +-------+
1472 // c) beg_bits: ... x x | 0 0 | || 0 x x ...
1473 // end_bits: ... x 1 | 0 0 | || 0 x x ...
1474 // +-------+
1475 // +-----------+
1476 // d) beg_bits: ... x | 0 0 0 | || 0 x x ...
1477 // end_bits: ... 1 | 0 0 0 | || 0 x x ...
1478 // +-----------+
1479 // +-------+
1480 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ...
1481 // end_bits: ... 0 0 | 0 0 | || 0 x x ...
1482 // +-------+
1483
1484 // Initially assume case a, c or e will apply.
1485 size_t obj_len = CollectedHeap::min_fill_size();
1486 HeapWord* obj_beg = dense_prefix_end - obj_len;
1487
1488 #ifdef _LP64
1489 if (MinObjAlignment > 1) { // object alignment > heap word size
1490 // Cases a, c or e.
1491 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1492 // Case b above.
1493 obj_beg = dense_prefix_end - 1;
1494 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1495 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1496 // Case d above.
1497 obj_beg = dense_prefix_end - 3;
1498 obj_len = 3;
1499 }
1500 #endif // #ifdef _LP64
1501
1502 CollectedHeap::fill_with_object(obj_beg, obj_len);
1503 _mark_bitmap.mark_obj(obj_beg, obj_len);
1504 _summary_data.add_obj(obj_beg, obj_len);
1505 assert(start_array(id) != NULL, "sanity");
1506 start_array(id)->allocate_block(obj_beg);
1507 }
1508 }
1509
1510 void
1511 PSParallelCompact::clear_source_region(HeapWord* beg_addr, HeapWord* end_addr)
1512 {
1513 RegionData* const beg_ptr = _summary_data.addr_to_region_ptr(beg_addr);
1514 HeapWord* const end_aligned_up = _summary_data.region_align_up(end_addr);
1515 RegionData* const end_ptr = _summary_data.addr_to_region_ptr(end_aligned_up);
1516 for (RegionData* cur = beg_ptr; cur < end_ptr; ++cur) {
1517 cur->set_source_region(0);
1518 }
1519 }
1520
1521 void
1522 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1523 {
1524 assert(id < last_space_id, "id out of range");
1525 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(),
1526 "should have been reset in summarize_spaces_quick()");
1527
1528 const MutableSpace* space = _space_info[id].space();
1529 if (_space_info[id].new_top() != space->bottom()) {
1530 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1531 _space_info[id].set_dense_prefix(dense_prefix_end);
1532
1533 #ifndef PRODUCT
1534 if (TraceParallelOldGCDensePrefix) {
1535 print_dense_prefix_stats("ratio", id, maximum_compaction,
1536 dense_prefix_end);
1537 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1538 print_dense_prefix_stats("density", id, maximum_compaction, addr);
1539 }
1540 #endif // #ifndef PRODUCT
1541
1542 // Recompute the summary data, taking into account the dense prefix. If
1543 // every last byte will be reclaimed, then the existing summary data which
1544 // compacts everything can be left in place.
1545 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1546 // If dead space crosses the dense prefix boundary, it is (at least
1547 // partially) filled with a dummy object, marked live and added to the
1548 // summary data. This simplifies the copy/update phase and must be done
1549 // before the final locations of objects are determined, to prevent
1550 // leaving a fragment of dead space that is too small to fill.
1551 fill_dense_prefix_end(id);
1552
1553 // Compute the destination of each Region, and thus each object.
1554 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1555 _summary_data.summarize(_space_info[id].split_info(),
1556 dense_prefix_end, space->top(), NULL,
1557 dense_prefix_end, space->end(),
1558 _space_info[id].new_top_addr());
1559 }
1560 }
1561
1562 if (TraceParallelOldGCSummaryPhase) {
1563 const size_t region_size = ParallelCompactData::RegionSize;
1564 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1565 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1566 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1567 HeapWord* const new_top = _space_info[id].new_top();
1568 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1569 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1570 tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1571 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1572 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1573 id, space->capacity_in_words(), p2i(dense_prefix_end),
1574 dp_region, dp_words / region_size,
1575 cr_words / region_size, p2i(new_top));
1576 }
1577 }
1578
1579 #ifndef PRODUCT
1580 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1581 HeapWord* dst_beg, HeapWord* dst_end,
1582 SpaceId src_space_id,
1583 HeapWord* src_beg, HeapWord* src_end)
1584 {
1585 if (TraceParallelOldGCSummaryPhase) {
1586 tty->print_cr("summarizing %d [%s] into %d [%s]: "
1587 "src=" PTR_FORMAT "-" PTR_FORMAT " "
1588 SIZE_FORMAT "-" SIZE_FORMAT " "
1589 "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1590 SIZE_FORMAT "-" SIZE_FORMAT,
1591 src_space_id, space_names[src_space_id],
1592 dst_space_id, space_names[dst_space_id],
1593 p2i(src_beg), p2i(src_end),
1594 _summary_data.addr_to_region_idx(src_beg),
1595 _summary_data.addr_to_region_idx(src_end),
1596 p2i(dst_beg), p2i(dst_end),
1597 _summary_data.addr_to_region_idx(dst_beg),
1598 _summary_data.addr_to_region_idx(dst_end));
1599 }
1600 }
1601 #endif // #ifndef PRODUCT
1602
1603 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1604 bool maximum_compaction)
1605 {
1606 GCTraceTime tm("summary phase", print_phases(), true, &_gc_timer);
1607 // trace("2");
1608
1609 #ifdef ASSERT
1610 if (TraceParallelOldGCMarkingPhase) {
1611 tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1612 "add_obj_bytes=" SIZE_FORMAT,
1613 add_obj_count, add_obj_size * HeapWordSize);
1614 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1615 "mark_bitmap_bytes=" SIZE_FORMAT,
1616 mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1617 }
1618 #endif // #ifdef ASSERT
1619
1620 // Quick summarization of each space into itself, to see how much is live.
1621 summarize_spaces_quick();
1622
1623 if (TraceParallelOldGCSummaryPhase) {
1624 tty->print_cr("summary_phase: after summarizing each space to self");
1625 Universe::print();
1626 NOT_PRODUCT(print_region_ranges());
1627 if (Verbose) {
1628 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1629 }
1630 }
1631
1632 // The amount of live data that will end up in old space (assuming it fits).
1633 size_t old_space_total_live = 0;
1634 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1635 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1636 _space_info[id].space()->bottom());
1637 }
1638
1639 MutableSpace* const old_space = _space_info[old_space_id].space();
1640 const size_t old_capacity = old_space->capacity_in_words();
1641 if (old_space_total_live > old_capacity) {
1642 // XXX - should also try to expand
1643 maximum_compaction = true;
1644 }
1645
1646 // Old generations.
1647 summarize_space(old_space_id, maximum_compaction);
1648
1649 // Summarize the remaining spaces in the young gen. The initial target space
1650 // is the old gen. If a space does not fit entirely into the target, then the
1651 // remainder is compacted into the space itself and that space becomes the new
1652 // target.
1653 SpaceId dst_space_id = old_space_id;
1654 HeapWord* dst_space_end = old_space->end();
1655 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1656 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1657 const MutableSpace* space = _space_info[id].space();
1658 const size_t live = pointer_delta(_space_info[id].new_top(),
1659 space->bottom());
1660 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1661
1662 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1663 SpaceId(id), space->bottom(), space->top());)
1664 if (live > 0 && live <= available) {
1665 // All the live data will fit.
1666 bool done = _summary_data.summarize(_space_info[id].split_info(),
1667 space->bottom(), space->top(),
1668 NULL,
1669 *new_top_addr, dst_space_end,
1670 new_top_addr);
1671 assert(done, "space must fit into old gen");
1672
1673 // Reset the new_top value for the space.
1674 _space_info[id].set_new_top(space->bottom());
1675 } else if (live > 0) {
1676 // Attempt to fit part of the source space into the target space.
1677 HeapWord* next_src_addr = NULL;
1678 bool done = _summary_data.summarize(_space_info[id].split_info(),
1679 space->bottom(), space->top(),
1680 &next_src_addr,
1681 *new_top_addr, dst_space_end,
1682 new_top_addr);
1683 assert(!done, "space should not fit into old gen");
1684 assert(next_src_addr != NULL, "sanity");
1685
1686 // The source space becomes the new target, so the remainder is compacted
1687 // within the space itself.
1688 dst_space_id = SpaceId(id);
1689 dst_space_end = space->end();
1690 new_top_addr = _space_info[id].new_top_addr();
1691 NOT_PRODUCT(summary_phase_msg(dst_space_id,
1692 space->bottom(), dst_space_end,
1693 SpaceId(id), next_src_addr, space->top());)
1694 done = _summary_data.summarize(_space_info[id].split_info(),
1695 next_src_addr, space->top(),
1696 NULL,
1697 space->bottom(), dst_space_end,
1698 new_top_addr);
1699 assert(done, "space must fit when compacted into itself");
1700 assert(*new_top_addr <= space->top(), "usage should not grow");
1701 }
1702 }
1703
1704 if (TraceParallelOldGCSummaryPhase) {
1705 tty->print_cr("summary_phase: after final summarization");
1706 Universe::print();
1707 NOT_PRODUCT(print_region_ranges());
1708 if (Verbose) {
1709 NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info));
1710 }
1711 }
1712 }
1713
1714 // This method should contain all heap-specific policy for invoking a full
1715 // collection. invoke_no_policy() will only attempt to compact the heap; it
1716 // will do nothing further. If we need to bail out for policy reasons, scavenge
1717 // before full gc, or any other specialized behavior, it needs to be added here.
1718 //
1719 // Note that this method should only be called from the vm_thread while at a
1720 // safepoint.
1721 //
1722 // Note that the all_soft_refs_clear flag in the collector policy
1723 // may be true because this method can be called without intervening
1724 // activity. For example when the heap space is tight and full measure
1725 // are being taken to free space.
1726 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1727 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1728 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1729 "should be in vm thread");
1730
1731 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1732 GCCause::Cause gc_cause = heap->gc_cause();
1733 assert(!heap->is_gc_active(), "not reentrant");
1734
1735 PSAdaptiveSizePolicy* policy = heap->size_policy();
1736 IsGCActiveMark mark;
1737
1738 if (ScavengeBeforeFullGC) {
1739 PSScavenge::invoke_no_policy();
1740 }
1741
1742 const bool clear_all_soft_refs =
1743 heap->collector_policy()->should_clear_all_soft_refs();
1744
1745 PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1746 maximum_heap_compaction);
1747 }
1748
1749 // This method contains no policy. You should probably
1750 // be calling invoke() instead.
1751 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1752 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1753 assert(ref_processor() != NULL, "Sanity");
1754
1755 if (GC_locker::check_active_before_gc()) {
1756 return false;
1757 }
1758
1759 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1760
1761 GCIdMark gc_id_mark;
1762 _gc_timer.register_gc_start();
1763 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
1764
1765 TimeStamp marking_start;
1766 TimeStamp compaction_start;
1767 TimeStamp collection_exit;
1768
1769 GCCause::Cause gc_cause = heap->gc_cause();
1770 PSYoungGen* young_gen = heap->young_gen();
1771 PSOldGen* old_gen = heap->old_gen();
1772 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1773
1774 // The scope of casr should end after code that can change
1775 // CollectorPolicy::_should_clear_all_soft_refs.
1776 ClearedAllSoftRefs casr(maximum_heap_compaction,
1777 heap->collector_policy());
1778
1779 if (ZapUnusedHeapArea) {
1780 // Save information needed to minimize mangling
1781 heap->record_gen_tops_before_GC();
1782 }
1783
1784 heap->pre_full_gc_dump(&_gc_timer);
1785
1786 _print_phases = PrintGCDetails && PrintParallelOldGCPhaseTimes;
1787
1788 // Make sure data structures are sane, make the heap parsable, and do other
1789 // miscellaneous bookkeeping.
1790 PreGCValues pre_gc_values;
1791 pre_compact(&pre_gc_values);
1792
1793 // Get the compaction manager reserved for the VM thread.
1794 ParCompactionManager* const vmthread_cm =
1795 ParCompactionManager::manager_array(gc_task_manager()->workers());
1796
1797 // Place after pre_compact() where the number of invocations is incremented.
1798 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
1799
1800 {
1801 ResourceMark rm;
1802 HandleMark hm;
1803
1804 // Set the number of GC threads to be used in this collection
1805 gc_task_manager()->set_active_gang();
1806 gc_task_manager()->task_idle_workers();
1807
1808 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
1809 GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL);
1810 TraceCollectorStats tcs(counters());
1811 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
1812
1813 if (TraceOldGenTime) accumulated_time()->start();
1814
1815 // Let the size policy know we're starting
1816 size_policy->major_collection_begin();
1817
1818 CodeCache::gc_prologue();
1819
1820 #if defined(COMPILER2) || INCLUDE_JVMCI
1821 DerivedPointerTable::clear();
1822 #endif
1823
1824 ref_processor()->enable_discovery();
1825 ref_processor()->setup_policy(maximum_heap_compaction);
1826
1827 bool marked_for_unloading = false;
1828
1829 marking_start.update();
1830 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer);
1831
1832 bool max_on_system_gc = UseMaximumCompactionOnSystemGC
1833 && GCCause::is_user_requested_gc(gc_cause);
1834 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
1835
1836 #if defined(COMPILER2) || INCLUDE_JVMCI
1837 assert(DerivedPointerTable::is_active(), "Sanity");
1838 DerivedPointerTable::set_active(false);
1839 #endif
1840
1841 // adjust_roots() updates Universe::_intArrayKlassObj which is
1842 // needed by the compaction for filling holes in the dense prefix.
1843 adjust_roots();
1844
1845 compaction_start.update();
1846 compact();
1847
1848 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
1849 // done before resizing.
1850 post_compact();
1851
1852 // Let the size policy know we're done
1853 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
1854
1855 if (UseAdaptiveSizePolicy) {
1856 if (PrintAdaptiveSizePolicy) {
1857 gclog_or_tty->print("AdaptiveSizeStart: ");
1858 gclog_or_tty->stamp();
1859 gclog_or_tty->print_cr(" collection: %d ",
1860 heap->total_collections());
1861 if (Verbose) {
1862 gclog_or_tty->print("old_gen_capacity: " SIZE_FORMAT
1863 " young_gen_capacity: " SIZE_FORMAT,
1864 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
1865 }
1866 }
1867
1868 // Don't check if the size_policy is ready here. Let
1869 // the size_policy check that internally.
1870 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
1871 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
1872 // Swap the survivor spaces if from_space is empty. The
1873 // resize_young_gen() called below is normally used after
1874 // a successful young GC and swapping of survivor spaces;
1875 // otherwise, it will fail to resize the young gen with
1876 // the current implementation.
1877 if (young_gen->from_space()->is_empty()) {
1878 young_gen->from_space()->clear(SpaceDecorator::Mangle);
1879 young_gen->swap_spaces();
1880 }
1881
1882 // Calculate optimal free space amounts
1883 assert(young_gen->max_size() >
1884 young_gen->from_space()->capacity_in_bytes() +
1885 young_gen->to_space()->capacity_in_bytes(),
1886 "Sizes of space in young gen are out-of-bounds");
1887
1888 size_t young_live = young_gen->used_in_bytes();
1889 size_t eden_live = young_gen->eden_space()->used_in_bytes();
1890 size_t old_live = old_gen->used_in_bytes();
1891 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
1892 size_t max_old_gen_size = old_gen->max_gen_size();
1893 size_t max_eden_size = young_gen->max_size() -
1894 young_gen->from_space()->capacity_in_bytes() -
1895 young_gen->to_space()->capacity_in_bytes();
1896
1897 // Used for diagnostics
1898 size_policy->clear_generation_free_space_flags();
1899
1900 size_policy->compute_generations_free_space(young_live,
1901 eden_live,
1902 old_live,
1903 cur_eden,
1904 max_old_gen_size,
1905 max_eden_size,
1906 true /* full gc*/);
1907
1908 size_policy->check_gc_overhead_limit(young_live,
1909 eden_live,
1910 max_old_gen_size,
1911 max_eden_size,
1912 true /* full gc*/,
1913 gc_cause,
1914 heap->collector_policy());
1915
1916 size_policy->decay_supplemental_growth(true /* full gc*/);
1917
1918 heap->resize_old_gen(
1919 size_policy->calculated_old_free_size_in_bytes());
1920
1921 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
1922 size_policy->calculated_survivor_size_in_bytes());
1923 }
1924 if (PrintAdaptiveSizePolicy) {
1925 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
1926 heap->total_collections());
1927 }
1928 }
1929
1930 if (UsePerfData) {
1931 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
1932 counters->update_counters();
1933 counters->update_old_capacity(old_gen->capacity_in_bytes());
1934 counters->update_young_capacity(young_gen->capacity_in_bytes());
1935 }
1936
1937 heap->resize_all_tlabs();
1938
1939 // Resize the metaspace capacity after a collection
1940 MetaspaceGC::compute_new_size();
1941
1942 if (TraceOldGenTime) accumulated_time()->stop();
1943
1944 if (PrintGC) {
1945 if (PrintGCDetails) {
1946 // No GC timestamp here. This is after GC so it would be confusing.
1947 young_gen->print_used_change(pre_gc_values.young_gen_used());
1948 old_gen->print_used_change(pre_gc_values.old_gen_used());
1949 heap->print_heap_change(pre_gc_values.heap_used());
1950 MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used());
1951 } else {
1952 heap->print_heap_change(pre_gc_values.heap_used());
1953 }
1954 }
1955
1956 // Track memory usage and detect low memory
1957 MemoryService::track_memory_usage();
1958 heap->update_counters();
1959 gc_task_manager()->release_idle_workers();
1960 }
1961
1962 #ifdef ASSERT
1963 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
1964 ParCompactionManager* const cm =
1965 ParCompactionManager::manager_array(int(i));
1966 assert(cm->marking_stack()->is_empty(), "should be empty");
1967 assert(ParCompactionManager::region_list(int(i))->is_empty(), "should be empty");
1968 }
1969 #endif // ASSERT
1970
1971 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1972 HandleMark hm; // Discard invalid handles created during verification
1973 Universe::verify(" VerifyAfterGC:");
1974 }
1975
1976 // Re-verify object start arrays
1977 if (VerifyObjectStartArray &&
1978 VerifyAfterGC) {
1979 old_gen->verify_object_start_array();
1980 }
1981
1982 if (ZapUnusedHeapArea) {
1983 old_gen->object_space()->check_mangled_unused_area_complete();
1984 }
1985
1986 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1987
1988 collection_exit.update();
1989
1990 heap->print_heap_after_gc();
1991 heap->trace_heap_after_gc(&_gc_tracer);
1992
1993 if (PrintGCTaskTimeStamps) {
1994 gclog_or_tty->print_cr("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " "
1995 JLONG_FORMAT,
1996 marking_start.ticks(), compaction_start.ticks(),
1997 collection_exit.ticks());
1998 gc_task_manager()->print_task_time_stamps();
1999 }
2000
2001 heap->post_full_gc_dump(&_gc_timer);
2002
2003 #ifdef TRACESPINNING
2004 ParallelTaskTerminator::print_termination_counts();
2005 #endif
2006
2007 _gc_timer.register_gc_end();
2008
2009 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
2010 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
2011
2012 return true;
2013 }
2014
2015 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
2016 PSYoungGen* young_gen,
2017 PSOldGen* old_gen) {
2018 MutableSpace* const eden_space = young_gen->eden_space();
2019 assert(!eden_space->is_empty(), "eden must be non-empty");
2020 assert(young_gen->virtual_space()->alignment() ==
2021 old_gen->virtual_space()->alignment(), "alignments do not match");
2022
2023 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
2024 return false;
2025 }
2026
2027 // Both generations must be completely committed.
2028 if (young_gen->virtual_space()->uncommitted_size() != 0) {
2029 return false;
2030 }
2031 if (old_gen->virtual_space()->uncommitted_size() != 0) {
2032 return false;
2033 }
2034
2035 // Figure out how much to take from eden. Include the average amount promoted
2036 // in the total; otherwise the next young gen GC will simply bail out to a
2037 // full GC.
2038 const size_t alignment = old_gen->virtual_space()->alignment();
2039 const size_t eden_used = eden_space->used_in_bytes();
2040 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
2041 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
2042 const size_t eden_capacity = eden_space->capacity_in_bytes();
2043
2044 if (absorb_size >= eden_capacity) {
2045 return false; // Must leave some space in eden.
2046 }
2047
2048 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2049 if (new_young_size < young_gen->min_gen_size()) {
2050 return false; // Respect young gen minimum size.
2051 }
2052
2053 if (TraceAdaptiveGCBoundary && Verbose) {
2054 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
2055 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2056 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2057 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2058 absorb_size / K,
2059 eden_capacity / K, (eden_capacity - absorb_size) / K,
2060 young_gen->from_space()->used_in_bytes() / K,
2061 young_gen->to_space()->used_in_bytes() / K,
2062 young_gen->capacity_in_bytes() / K, new_young_size / K);
2063 }
2064
2065 // Fill the unused part of the old gen.
2066 MutableSpace* const old_space = old_gen->object_space();
2067 HeapWord* const unused_start = old_space->top();
2068 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2069
2070 if (unused_words > 0) {
2071 if (unused_words < CollectedHeap::min_fill_size()) {
2072 return false; // If the old gen cannot be filled, must give up.
2073 }
2074 CollectedHeap::fill_with_objects(unused_start, unused_words);
2075 }
2076
2077 // Take the live data from eden and set both top and end in the old gen to
2078 // eden top. (Need to set end because reset_after_change() mangles the region
2079 // from end to virtual_space->high() in debug builds).
2080 HeapWord* const new_top = eden_space->top();
2081 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2082 absorb_size);
2083 young_gen->reset_after_change();
2084 old_space->set_top(new_top);
2085 old_space->set_end(new_top);
2086 old_gen->reset_after_change();
2087
2088 // Update the object start array for the filler object and the data from eden.
2089 ObjectStartArray* const start_array = old_gen->start_array();
2090 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2091 start_array->allocate_block(p);
2092 }
2093
2094 // Could update the promoted average here, but it is not typically updated at
2095 // full GCs and the value to use is unclear. Something like
2096 //
2097 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2098
2099 size_policy->set_bytes_absorbed_from_eden(absorb_size);
2100 return true;
2101 }
2102
2103 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2104 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2105 "shouldn't return NULL");
2106 return ParallelScavengeHeap::gc_task_manager();
2107 }
2108
2109 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2110 bool maximum_heap_compaction,
2111 ParallelOldTracer *gc_tracer) {
2112 // Recursively traverse all live objects and mark them
2113 GCTraceTime tm("marking phase", print_phases(), true, &_gc_timer);
2114
2115 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2116 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2117 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2118 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2119 ParallelTaskTerminator terminator(active_gc_threads, qset);
2120
2121 ParCompactionManager::MarkAndPushClosure mark_and_push_closure(cm);
2122 ParCompactionManager::FollowStackClosure follow_stack_closure(cm);
2123
2124 // Need new claim bits before marking starts.
2125 ClassLoaderDataGraph::clear_claimed_marks();
2126
2127 {
2128 GCTraceTime tm_m("par mark", print_phases(), true, &_gc_timer);
2129
2130 ParallelScavengeHeap::ParStrongRootsScope psrs;
2131
2132 GCTaskQueue* q = GCTaskQueue::create();
2133
2134 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2135 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2136 // We scan the thread roots in parallel
2137 Threads::create_thread_roots_marking_tasks(q);
2138 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2139 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
2140 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2141 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2142 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data));
2143 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2144 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2145
2146 if (active_gc_threads > 1) {
2147 for (uint j = 0; j < active_gc_threads; j++) {
2148 q->enqueue(new StealMarkingTask(&terminator));
2149 }
2150 }
2151
2152 gc_task_manager()->execute_and_wait(q);
2153 }
2154
2155 // Process reference objects found during marking
2156 {
2157 GCTraceTime tm_r("reference processing", print_phases(), true, &_gc_timer);
2158
2159 ReferenceProcessorStats stats;
2160 if (ref_processor()->processing_is_mt()) {
2161 RefProcTaskExecutor task_executor;
2162 stats = ref_processor()->process_discovered_references(
2163 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2164 &task_executor, &_gc_timer);
2165 } else {
2166 stats = ref_processor()->process_discovered_references(
2167 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
2168 &_gc_timer);
2169 }
2170
2171 gc_tracer->report_gc_reference_stats(stats);
2172 }
2173
2174 GCTraceTime tm_c("class unloading", print_phases(), true, &_gc_timer);
2175
2176 // This is the point where the entire marking should have completed.
2177 assert(cm->marking_stacks_empty(), "Marking should have completed");
2178
2179 // Follow system dictionary roots and unload classes.
2180 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
2181
2182 // Unload nmethods.
2183 CodeCache::do_unloading(is_alive_closure(), purged_class);
2184
2185 // Prune dead klasses from subklass/sibling/implementor lists.
2186 Klass::clean_weak_klass_links(is_alive_closure());
2187
2188 // Delete entries for dead interned strings.
2189 StringTable::unlink(is_alive_closure());
2190
2191 // Clean up unreferenced symbols in symbol table.
2192 SymbolTable::unlink();
2193 _gc_tracer.report_object_count_after_gc(is_alive_closure());
2194 }
2195
2196 // This should be moved to the shared markSweep code!
2197 class PSAlwaysTrueClosure: public BoolObjectClosure {
2198 public:
2199 bool do_object_b(oop p) { return true; }
2200 };
2201 static PSAlwaysTrueClosure always_true;
2202
2203 void PSParallelCompact::adjust_roots() {
2204 // Adjust the pointers to reflect the new locations
2205 GCTraceTime tm("adjust roots", print_phases(), true, &_gc_timer);
2206
2207 // Need new claim bits when tracing through and adjusting pointers.
2208 ClassLoaderDataGraph::clear_claimed_marks();
2209
2210 // General strong roots.
2211 Universe::oops_do(adjust_pointer_closure());
2212 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
2213 CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
2214 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
2215 ObjectSynchronizer::oops_do(adjust_pointer_closure());
2216 FlatProfiler::oops_do(adjust_pointer_closure());
2217 Management::oops_do(adjust_pointer_closure());
2218 JvmtiExport::oops_do(adjust_pointer_closure());
2219 SystemDictionary::oops_do(adjust_pointer_closure());
2220 ClassLoaderDataGraph::oops_do(adjust_pointer_closure(), adjust_klass_closure(), true);
2221
2222 // Now adjust pointers in remaining weak roots. (All of which should
2223 // have been cleared if they pointed to non-surviving objects.)
2224 // Global (weak) JNI handles
2225 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure());
2226
2227 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations);
2228 CodeCache::blobs_do(&adjust_from_blobs);
2229 StringTable::oops_do(adjust_pointer_closure());
2230 ref_processor()->weak_oops_do(adjust_pointer_closure());
2231 // Roots were visited so references into the young gen in roots
2232 // may have been scanned. Process them also.
2233 // Should the reference processor have a span that excludes
2234 // young gen objects?
2235 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
2236 }
2237
2238 void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q,
2239 uint parallel_gc_threads)
2240 {
2241 GCTraceTime tm("drain task setup", print_phases(), true, &_gc_timer);
2242
2243 // Find the threads that are active
2244 unsigned int which = 0;
2245
2246 const uint task_count = MAX2(parallel_gc_threads, 1U);
2247 for (uint j = 0; j < task_count; j++) {
2248 q->enqueue(new DrainStacksCompactionTask(j));
2249 ParCompactionManager::verify_region_list_empty(j);
2250 // Set the region stacks variables to "no" region stack values
2251 // so that they will be recognized and needing a region stack
2252 // in the stealing tasks if they do not get one by executing
2253 // a draining stack.
2254 ParCompactionManager* cm = ParCompactionManager::manager_array(j);
2255 cm->set_region_stack(NULL);
2256 cm->set_region_stack_index((uint)max_uintx);
2257 }
2258 ParCompactionManager::reset_recycled_stack_index();
2259
2260 // Find all regions that are available (can be filled immediately) and
2261 // distribute them to the thread stacks. The iteration is done in reverse
2262 // order (high to low) so the regions will be removed in ascending order.
2263
2264 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2265
2266 size_t fillable_regions = 0; // A count for diagnostic purposes.
2267 // A region index which corresponds to the tasks created above.
2268 // "which" must be 0 <= which < task_count
2269
2270 which = 0;
2271 // id + 1 is used to test termination so unsigned can
2272 // be used with an old_space_id == 0.
2273 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2274 SpaceInfo* const space_info = _space_info + id;
2275 MutableSpace* const space = space_info->space();
2276 HeapWord* const new_top = space_info->new_top();
2277
2278 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2279 const size_t end_region =
2280 sd.addr_to_region_idx(sd.region_align_up(new_top));
2281
2282 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2283 if (sd.region(cur)->claim_unsafe()) {
2284 ParCompactionManager::region_list_push(which, cur);
2285
2286 if (TraceParallelOldGCCompactionPhase && Verbose) {
2287 const size_t count_mod_8 = fillable_regions & 7;
2288 if (count_mod_8 == 0) gclog_or_tty->print("fillable: ");
2289 gclog_or_tty->print(" " SIZE_FORMAT_W(7), cur);
2290 if (count_mod_8 == 7) gclog_or_tty->cr();
2291 }
2292
2293 NOT_PRODUCT(++fillable_regions;)
2294
2295 // Assign regions to tasks in round-robin fashion.
2296 if (++which == task_count) {
2297 assert(which <= parallel_gc_threads,
2298 "Inconsistent number of workers");
2299 which = 0;
2300 }
2301 }
2302 }
2303 }
2304
2305 if (TraceParallelOldGCCompactionPhase) {
2306 if (Verbose && (fillable_regions & 7) != 0) gclog_or_tty->cr();
2307 gclog_or_tty->print_cr(SIZE_FORMAT " initially fillable regions", fillable_regions);
2308 }
2309 }
2310
2311 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2312
2313 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2314 uint parallel_gc_threads) {
2315 GCTraceTime tm("dense prefix task setup", print_phases(), true, &_gc_timer);
2316
2317 ParallelCompactData& sd = PSParallelCompact::summary_data();
2318
2319 // Iterate over all the spaces adding tasks for updating
2320 // regions in the dense prefix. Assume that 1 gc thread
2321 // will work on opening the gaps and the remaining gc threads
2322 // will work on the dense prefix.
2323 unsigned int space_id;
2324 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2325 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2326 const MutableSpace* const space = _space_info[space_id].space();
2327
2328 if (dense_prefix_end == space->bottom()) {
2329 // There is no dense prefix for this space.
2330 continue;
2331 }
2332
2333 // The dense prefix is before this region.
2334 size_t region_index_end_dense_prefix =
2335 sd.addr_to_region_idx(dense_prefix_end);
2336 RegionData* const dense_prefix_cp =
2337 sd.region(region_index_end_dense_prefix);
2338 assert(dense_prefix_end == space->end() ||
2339 dense_prefix_cp->available() ||
2340 dense_prefix_cp->claimed(),
2341 "The region after the dense prefix should always be ready to fill");
2342
2343 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2344
2345 // Is there dense prefix work?
2346 size_t total_dense_prefix_regions =
2347 region_index_end_dense_prefix - region_index_start;
2348 // How many regions of the dense prefix should be given to
2349 // each thread?
2350 if (total_dense_prefix_regions > 0) {
2351 uint tasks_for_dense_prefix = 1;
2352 if (total_dense_prefix_regions <=
2353 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2354 // Don't over partition. This assumes that
2355 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2356 // so there are not many regions to process.
2357 tasks_for_dense_prefix = parallel_gc_threads;
2358 } else {
2359 // Over partition
2360 tasks_for_dense_prefix = parallel_gc_threads *
2361 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2362 }
2363 size_t regions_per_thread = total_dense_prefix_regions /
2364 tasks_for_dense_prefix;
2365 // Give each thread at least 1 region.
2366 if (regions_per_thread == 0) {
2367 regions_per_thread = 1;
2368 }
2369
2370 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2371 if (region_index_start >= region_index_end_dense_prefix) {
2372 break;
2373 }
2374 // region_index_end is not processed
2375 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2376 region_index_end_dense_prefix);
2377 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2378 region_index_start,
2379 region_index_end));
2380 region_index_start = region_index_end;
2381 }
2382 }
2383 // This gets any part of the dense prefix that did not
2384 // fit evenly.
2385 if (region_index_start < region_index_end_dense_prefix) {
2386 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2387 region_index_start,
2388 region_index_end_dense_prefix));
2389 }
2390 }
2391 }
2392
2393 void PSParallelCompact::enqueue_region_stealing_tasks(
2394 GCTaskQueue* q,
2395 ParallelTaskTerminator* terminator_ptr,
2396 uint parallel_gc_threads) {
2397 GCTraceTime tm("steal task setup", print_phases(), true, &_gc_timer);
2398
2399 // Once a thread has drained it's stack, it should try to steal regions from
2400 // other threads.
2401 if (parallel_gc_threads > 1) {
2402 for (uint j = 0; j < parallel_gc_threads; j++) {
2403 q->enqueue(new StealRegionCompactionTask(terminator_ptr));
2404 }
2405 }
2406 }
2407
2408 #ifdef ASSERT
2409 // Write a histogram of the number of times the block table was filled for a
2410 // region.
2411 void PSParallelCompact::write_block_fill_histogram(outputStream* const out)
2412 {
2413 if (!TraceParallelOldGCCompactionPhase) return;
2414
2415 typedef ParallelCompactData::RegionData rd_t;
2416 ParallelCompactData& sd = summary_data();
2417
2418 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2419 MutableSpace* const spc = _space_info[id].space();
2420 if (spc->bottom() != spc->top()) {
2421 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
2422 HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
2423 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
2424
2425 size_t histo[5] = { 0, 0, 0, 0, 0 };
2426 const size_t histo_len = sizeof(histo) / sizeof(size_t);
2427 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
2428
2429 for (const rd_t* cur = beg; cur < end; ++cur) {
2430 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
2431 }
2432 out->print("%u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
2433 for (size_t i = 0; i < histo_len; ++i) {
2434 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
2435 histo[i], 100.0 * histo[i] / region_cnt);
2436 }
2437 out->cr();
2438 }
2439 }
2440 }
2441 #endif // #ifdef ASSERT
2442
2443 void PSParallelCompact::compact() {
2444 // trace("5");
2445 GCTraceTime tm("compaction phase", print_phases(), true, &_gc_timer);
2446
2447 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2448 PSOldGen* old_gen = heap->old_gen();
2449 old_gen->start_array()->reset();
2450 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2451 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2452 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2453 ParallelTaskTerminator terminator(active_gc_threads, qset);
2454
2455 GCTaskQueue* q = GCTaskQueue::create();
2456 enqueue_region_draining_tasks(q, active_gc_threads);
2457 enqueue_dense_prefix_tasks(q, active_gc_threads);
2458 enqueue_region_stealing_tasks(q, &terminator, active_gc_threads);
2459
2460 {
2461 GCTraceTime tm_pc("par compact", print_phases(), true, &_gc_timer);
2462
2463 gc_task_manager()->execute_and_wait(q);
2464
2465 #ifdef ASSERT
2466 // Verify that all regions have been processed before the deferred updates.
2467 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2468 verify_complete(SpaceId(id));
2469 }
2470 #endif
2471 }
2472
2473 {
2474 // Update the deferred objects, if any. Any compaction manager can be used.
2475 GCTraceTime tm_du("deferred updates", print_phases(), true, &_gc_timer);
2476 ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2477 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2478 update_deferred_objects(cm, SpaceId(id));
2479 }
2480 }
2481
2482 DEBUG_ONLY(write_block_fill_histogram(gclog_or_tty));
2483 }
2484
2485 #ifdef ASSERT
2486 void PSParallelCompact::verify_complete(SpaceId space_id) {
2487 // All Regions between space bottom() to new_top() should be marked as filled
2488 // and all Regions between new_top() and top() should be available (i.e.,
2489 // should have been emptied).
2490 ParallelCompactData& sd = summary_data();
2491 SpaceInfo si = _space_info[space_id];
2492 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2493 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2494 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2495 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2496 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2497
2498 bool issued_a_warning = false;
2499
2500 size_t cur_region;
2501 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2502 const RegionData* const c = sd.region(cur_region);
2503 if (!c->completed()) {
2504 warning("region " SIZE_FORMAT " not filled: "
2505 "destination_count=%u",
2506 cur_region, c->destination_count());
2507 issued_a_warning = true;
2508 }
2509 }
2510
2511 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2512 const RegionData* const c = sd.region(cur_region);
2513 if (!c->available()) {
2514 warning("region " SIZE_FORMAT " not empty: "
2515 "destination_count=%u",
2516 cur_region, c->destination_count());
2517 issued_a_warning = true;
2518 }
2519 }
2520
2521 if (issued_a_warning) {
2522 print_region_ranges();
2523 }
2524 }
2525 #endif // #ifdef ASSERT
2526
2527 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) {
2528 _start_array->allocate_block(addr);
2529 compaction_manager()->update_contents(oop(addr));
2530 }
2531
2532 // Update interior oops in the ranges of regions [beg_region, end_region).
2533 void
2534 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2535 SpaceId space_id,
2536 size_t beg_region,
2537 size_t end_region) {
2538 ParallelCompactData& sd = summary_data();
2539 ParMarkBitMap* const mbm = mark_bitmap();
2540
2541 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2542 HeapWord* const end_addr = sd.region_to_addr(end_region);
2543 assert(beg_region <= end_region, "bad region range");
2544 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2545
2546 #ifdef ASSERT
2547 // Claim the regions to avoid triggering an assert when they are marked as
2548 // filled.
2549 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2550 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2551 }
2552 #endif // #ifdef ASSERT
2553
2554 if (beg_addr != space(space_id)->bottom()) {
2555 // Find the first live object or block of dead space that *starts* in this
2556 // range of regions. If a partial object crosses onto the region, skip it;
2557 // it will be marked for 'deferred update' when the object head is
2558 // processed. If dead space crosses onto the region, it is also skipped; it
2559 // will be filled when the prior region is processed. If neither of those
2560 // apply, the first word in the region is the start of a live object or dead
2561 // space.
2562 assert(beg_addr > space(space_id)->bottom(), "sanity");
2563 const RegionData* const cp = sd.region(beg_region);
2564 if (cp->partial_obj_size() != 0) {
2565 beg_addr = sd.partial_obj_end(beg_region);
2566 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2567 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2568 }
2569 }
2570
2571 if (beg_addr < end_addr) {
2572 // A live object or block of dead space starts in this range of Regions.
2573 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2574
2575 // Create closures and iterate.
2576 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2577 FillClosure fill_closure(cm, space_id);
2578 ParMarkBitMap::IterationStatus status;
2579 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2580 dense_prefix_end);
2581 if (status == ParMarkBitMap::incomplete) {
2582 update_closure.do_addr(update_closure.source());
2583 }
2584 }
2585
2586 // Mark the regions as filled.
2587 RegionData* const beg_cp = sd.region(beg_region);
2588 RegionData* const end_cp = sd.region(end_region);
2589 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2590 cp->set_completed();
2591 }
2592 }
2593
2594 // Return the SpaceId for the space containing addr. If addr is not in the
2595 // heap, last_space_id is returned. In debug mode it expects the address to be
2596 // in the heap and asserts such.
2597 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2598 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
2599
2600 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2601 if (_space_info[id].space()->contains(addr)) {
2602 return SpaceId(id);
2603 }
2604 }
2605
2606 assert(false, "no space contains the addr");
2607 return last_space_id;
2608 }
2609
2610 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2611 SpaceId id) {
2612 assert(id < last_space_id, "bad space id");
2613
2614 ParallelCompactData& sd = summary_data();
2615 const SpaceInfo* const space_info = _space_info + id;
2616 ObjectStartArray* const start_array = space_info->start_array();
2617
2618 const MutableSpace* const space = space_info->space();
2619 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2620 HeapWord* const beg_addr = space_info->dense_prefix();
2621 HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2622
2623 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2624 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2625 const RegionData* cur_region;
2626 for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2627 HeapWord* const addr = cur_region->deferred_obj_addr();
2628 if (addr != NULL) {
2629 if (start_array != NULL) {
2630 start_array->allocate_block(addr);
2631 }
2632 cm->update_contents(oop(addr));
2633 assert(oop(addr)->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(addr)));
2634 }
2635 }
2636 }
2637
2638 // Skip over count live words starting from beg, and return the address of the
2639 // next live word. Unless marked, the word corresponding to beg is assumed to
2640 // be dead. Callers must either ensure beg does not correspond to the middle of
2641 // an object, or account for those live words in some other way. Callers must
2642 // also ensure that there are enough live words in the range [beg, end) to skip.
2643 HeapWord*
2644 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2645 {
2646 assert(count > 0, "sanity");
2647
2648 ParMarkBitMap* m = mark_bitmap();
2649 idx_t bits_to_skip = m->words_to_bits(count);
2650 idx_t cur_beg = m->addr_to_bit(beg);
2651 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
2652
2653 do {
2654 cur_beg = m->find_obj_beg(cur_beg, search_end);
2655 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2656 const size_t obj_bits = cur_end - cur_beg + 1;
2657 if (obj_bits > bits_to_skip) {
2658 return m->bit_to_addr(cur_beg + bits_to_skip);
2659 }
2660 bits_to_skip -= obj_bits;
2661 cur_beg = cur_end + 1;
2662 } while (bits_to_skip > 0);
2663
2664 // Skipping the desired number of words landed just past the end of an object.
2665 // Find the start of the next object.
2666 cur_beg = m->find_obj_beg(cur_beg, search_end);
2667 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2668 return m->bit_to_addr(cur_beg);
2669 }
2670
2671 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2672 SpaceId src_space_id,
2673 size_t src_region_idx)
2674 {
2675 assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2676
2677 const SplitInfo& split_info = _space_info[src_space_id].split_info();
2678 if (split_info.dest_region_addr() == dest_addr) {
2679 // The partial object ending at the split point contains the first word to
2680 // be copied to dest_addr.
2681 return split_info.first_src_addr();
2682 }
2683
2684 const ParallelCompactData& sd = summary_data();
2685 ParMarkBitMap* const bitmap = mark_bitmap();
2686 const size_t RegionSize = ParallelCompactData::RegionSize;
2687
2688 assert(sd.is_region_aligned(dest_addr), "not aligned");
2689 const RegionData* const src_region_ptr = sd.region(src_region_idx);
2690 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2691 HeapWord* const src_region_destination = src_region_ptr->destination();
2692
2693 assert(dest_addr >= src_region_destination, "wrong src region");
2694 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2695
2696 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2697 HeapWord* const src_region_end = src_region_beg + RegionSize;
2698
2699 HeapWord* addr = src_region_beg;
2700 if (dest_addr == src_region_destination) {
2701 // Return the first live word in the source region.
2702 if (partial_obj_size == 0) {
2703 addr = bitmap->find_obj_beg(addr, src_region_end);
2704 assert(addr < src_region_end, "no objects start in src region");
2705 }
2706 return addr;
2707 }
2708
2709 // Must skip some live data.
2710 size_t words_to_skip = dest_addr - src_region_destination;
2711 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2712
2713 if (partial_obj_size >= words_to_skip) {
2714 // All the live words to skip are part of the partial object.
2715 addr += words_to_skip;
2716 if (partial_obj_size == words_to_skip) {
2717 // Find the first live word past the partial object.
2718 addr = bitmap->find_obj_beg(addr, src_region_end);
2719 assert(addr < src_region_end, "wrong src region");
2720 }
2721 return addr;
2722 }
2723
2724 // Skip over the partial object (if any).
2725 if (partial_obj_size != 0) {
2726 words_to_skip -= partial_obj_size;
2727 addr += partial_obj_size;
2728 }
2729
2730 // Skip over live words due to objects that start in the region.
2731 addr = skip_live_words(addr, src_region_end, words_to_skip);
2732 assert(addr < src_region_end, "wrong src region");
2733 return addr;
2734 }
2735
2736 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2737 SpaceId src_space_id,
2738 size_t beg_region,
2739 HeapWord* end_addr)
2740 {
2741 ParallelCompactData& sd = summary_data();
2742
2743 #ifdef ASSERT
2744 MutableSpace* const src_space = _space_info[src_space_id].space();
2745 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2746 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2747 "src_space_id does not match beg_addr");
2748 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2749 "src_space_id does not match end_addr");
2750 #endif // #ifdef ASSERT
2751
2752 RegionData* const beg = sd.region(beg_region);
2753 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2754
2755 // Regions up to new_top() are enqueued if they become available.
2756 HeapWord* const new_top = _space_info[src_space_id].new_top();
2757 RegionData* const enqueue_end =
2758 sd.addr_to_region_ptr(sd.region_align_up(new_top));
2759
2760 for (RegionData* cur = beg; cur < end; ++cur) {
2761 assert(cur->data_size() > 0, "region must have live data");
2762 cur->decrement_destination_count();
2763 if (cur < enqueue_end && cur->available() && cur->claim()) {
2764 cm->push_region(sd.region(cur));
2765 }
2766 }
2767 }
2768
2769 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2770 SpaceId& src_space_id,
2771 HeapWord*& src_space_top,
2772 HeapWord* end_addr)
2773 {
2774 typedef ParallelCompactData::RegionData RegionData;
2775
2776 ParallelCompactData& sd = PSParallelCompact::summary_data();
2777 const size_t region_size = ParallelCompactData::RegionSize;
2778
2779 size_t src_region_idx = 0;
2780
2781 // Skip empty regions (if any) up to the top of the space.
2782 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2783 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2784 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2785 const RegionData* const top_region_ptr =
2786 sd.addr_to_region_ptr(top_aligned_up);
2787 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2788 ++src_region_ptr;
2789 }
2790
2791 if (src_region_ptr < top_region_ptr) {
2792 // The next source region is in the current space. Update src_region_idx
2793 // and the source address to match src_region_ptr.
2794 src_region_idx = sd.region(src_region_ptr);
2795 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
2796 if (src_region_addr > closure.source()) {
2797 closure.set_source(src_region_addr);
2798 }
2799 return src_region_idx;
2800 }
2801
2802 // Switch to a new source space and find the first non-empty region.
2803 unsigned int space_id = src_space_id + 1;
2804 assert(space_id < last_space_id, "not enough spaces");
2805
2806 HeapWord* const destination = closure.destination();
2807
2808 do {
2809 MutableSpace* space = _space_info[space_id].space();
2810 HeapWord* const bottom = space->bottom();
2811 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
2812
2813 // Iterate over the spaces that do not compact into themselves.
2814 if (bottom_cp->destination() != bottom) {
2815 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
2816 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
2817
2818 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
2819 if (src_cp->live_obj_size() > 0) {
2820 // Found it.
2821 assert(src_cp->destination() == destination,
2822 "first live obj in the space must match the destination");
2823 assert(src_cp->partial_obj_size() == 0,
2824 "a space cannot begin with a partial obj");
2825
2826 src_space_id = SpaceId(space_id);
2827 src_space_top = space->top();
2828 const size_t src_region_idx = sd.region(src_cp);
2829 closure.set_source(sd.region_to_addr(src_region_idx));
2830 return src_region_idx;
2831 } else {
2832 assert(src_cp->data_size() == 0, "sanity");
2833 }
2834 }
2835 }
2836 } while (++space_id < last_space_id);
2837
2838 assert(false, "no source region was found");
2839 return 0;
2840 }
2841
2842 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
2843 {
2844 typedef ParMarkBitMap::IterationStatus IterationStatus;
2845 const size_t RegionSize = ParallelCompactData::RegionSize;
2846 ParMarkBitMap* const bitmap = mark_bitmap();
2847 ParallelCompactData& sd = summary_data();
2848 RegionData* const region_ptr = sd.region(region_idx);
2849
2850 // Get the items needed to construct the closure.
2851 HeapWord* dest_addr = sd.region_to_addr(region_idx);
2852 SpaceId dest_space_id = space_id(dest_addr);
2853 ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
2854 HeapWord* new_top = _space_info[dest_space_id].new_top();
2855 assert(dest_addr < new_top, "sanity");
2856 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
2857
2858 // Get the source region and related info.
2859 size_t src_region_idx = region_ptr->source_region();
2860 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2861 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2862
2863 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
2864 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2865
2866 // Adjust src_region_idx to prepare for decrementing destination counts (the
2867 // destination count is not decremented when a region is copied to itself).
2868 if (src_region_idx == region_idx) {
2869 src_region_idx += 1;
2870 }
2871
2872 if (bitmap->is_unmarked(closure.source())) {
2873 // The first source word is in the middle of an object; copy the remainder
2874 // of the object or as much as will fit. The fact that pointer updates were
2875 // deferred will be noted when the object header is processed.
2876 HeapWord* const old_src_addr = closure.source();
2877 closure.copy_partial_obj();
2878 if (closure.is_full()) {
2879 decrement_destination_counts(cm, src_space_id, src_region_idx,
2880 closure.source());
2881 region_ptr->set_deferred_obj_addr(NULL);
2882 region_ptr->set_completed();
2883 return;
2884 }
2885
2886 HeapWord* const end_addr = sd.region_align_down(closure.source());
2887 if (sd.region_align_down(old_src_addr) != end_addr) {
2888 // The partial object was copied from more than one source region.
2889 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2890
2891 // Move to the next source region, possibly switching spaces as well. All
2892 // args except end_addr may be modified.
2893 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2894 end_addr);
2895 }
2896 }
2897
2898 do {
2899 HeapWord* const cur_addr = closure.source();
2900 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2901 src_space_top);
2902 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
2903
2904 if (status == ParMarkBitMap::incomplete) {
2905 // The last obj that starts in the source region does not end in the
2906 // region.
2907 assert(closure.source() < end_addr, "sanity");
2908 HeapWord* const obj_beg = closure.source();
2909 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
2910 src_space_top);
2911 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
2912 if (obj_end < range_end) {
2913 // The end was found; the entire object will fit.
2914 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
2915 assert(status != ParMarkBitMap::would_overflow, "sanity");
2916 } else {
2917 // The end was not found; the object will not fit.
2918 assert(range_end < src_space_top, "obj cannot cross space boundary");
2919 status = ParMarkBitMap::would_overflow;
2920 }
2921 }
2922
2923 if (status == ParMarkBitMap::would_overflow) {
2924 // The last object did not fit. Note that interior oop updates were
2925 // deferred, then copy enough of the object to fill the region.
2926 region_ptr->set_deferred_obj_addr(closure.destination());
2927 status = closure.copy_until_full(); // copies from closure.source()
2928
2929 decrement_destination_counts(cm, src_space_id, src_region_idx,
2930 closure.source());
2931 region_ptr->set_completed();
2932 return;
2933 }
2934
2935 if (status == ParMarkBitMap::full) {
2936 decrement_destination_counts(cm, src_space_id, src_region_idx,
2937 closure.source());
2938 region_ptr->set_deferred_obj_addr(NULL);
2939 region_ptr->set_completed();
2940 return;
2941 }
2942
2943 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2944
2945 // Move to the next source region, possibly switching spaces as well. All
2946 // args except end_addr may be modified.
2947 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2948 end_addr);
2949 } while (true);
2950 }
2951
2952 void PSParallelCompact::fill_blocks(size_t region_idx)
2953 {
2954 // Fill in the block table elements for the specified region. Each block
2955 // table element holds the number of live words in the region that are to the
2956 // left of the first object that starts in the block. Thus only blocks in
2957 // which an object starts need to be filled.
2958 //
2959 // The algorithm scans the section of the bitmap that corresponds to the
2960 // region, keeping a running total of the live words. When an object start is
2961 // found, if it's the first to start in the block that contains it, the
2962 // current total is written to the block table element.
2963 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
2964 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
2965 const size_t RegionSize = ParallelCompactData::RegionSize;
2966
2967 ParallelCompactData& sd = summary_data();
2968 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
2969 if (partial_obj_size >= RegionSize) {
2970 return; // No objects start in this region.
2971 }
2972
2973 // Ensure the first loop iteration decides that the block has changed.
2974 size_t cur_block = sd.block_count();
2975
2976 const ParMarkBitMap* const bitmap = mark_bitmap();
2977
2978 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
2979 assert((size_t)1 << Log2BitsPerBlock ==
2980 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
2981
2982 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
2983 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
2984 size_t live_bits = bitmap->words_to_bits(partial_obj_size);
2985 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
2986 while (beg_bit < range_end) {
2987 const size_t new_block = beg_bit >> Log2BitsPerBlock;
2988 if (new_block != cur_block) {
2989 cur_block = new_block;
2990 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
2991 }
2992
2993 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
2994 if (end_bit < range_end - 1) {
2995 live_bits += end_bit - beg_bit + 1;
2996 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
2997 } else {
2998 return;
2999 }
3000 }
3001 }
3002
3003 void
3004 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
3005 const MutableSpace* sp = space(space_id);
3006 if (sp->is_empty()) {
3007 return;
3008 }
3009
3010 ParallelCompactData& sd = PSParallelCompact::summary_data();
3011 ParMarkBitMap* const bitmap = mark_bitmap();
3012 HeapWord* const dp_addr = dense_prefix(space_id);
3013 HeapWord* beg_addr = sp->bottom();
3014 HeapWord* end_addr = sp->top();
3015
3016 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
3017
3018 const size_t beg_region = sd.addr_to_region_idx(beg_addr);
3019 const size_t dp_region = sd.addr_to_region_idx(dp_addr);
3020 if (beg_region < dp_region) {
3021 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
3022 }
3023
3024 // The destination of the first live object that starts in the region is one
3025 // past the end of the partial object entering the region (if any).
3026 HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3027 HeapWord* const new_top = _space_info[space_id].new_top();
3028 assert(new_top >= dest_addr, "bad new_top value");
3029 const size_t words = pointer_delta(new_top, dest_addr);
3030
3031 if (words > 0) {
3032 ObjectStartArray* start_array = _space_info[space_id].start_array();
3033 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3034
3035 ParMarkBitMap::IterationStatus status;
3036 status = bitmap->iterate(&closure, dest_addr, end_addr);
3037 assert(status == ParMarkBitMap::full, "iteration not complete");
3038 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3039 "live objects skipped because closure is full");
3040 }
3041 }
3042
3043 jlong PSParallelCompact::millis_since_last_gc() {
3044 // We need a monotonically non-decreasing time in ms but
3045 // os::javaTimeMillis() does not guarantee monotonicity.
3046 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3047 jlong ret_val = now - _time_of_last_gc;
3048 // XXX See note in genCollectedHeap::millis_since_last_gc().
3049 if (ret_val < 0) {
3050 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, ret_val);)
3051 return 0;
3052 }
3053 return ret_val;
3054 }
3055
3056 void PSParallelCompact::reset_millis_since_last_gc() {
3057 // We need a monotonically non-decreasing time in ms but
3058 // os::javaTimeMillis() does not guarantee monotonicity.
3059 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3060 }
3061
3062 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3063 {
3064 if (source() != destination()) {
3065 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3066 Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3067 }
3068 update_state(words_remaining());
3069 assert(is_full(), "sanity");
3070 return ParMarkBitMap::full;
3071 }
3072
3073 void MoveAndUpdateClosure::copy_partial_obj()
3074 {
3075 size_t words = words_remaining();
3076
3077 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3078 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3079 if (end_addr < range_end) {
3080 words = bitmap()->obj_size(source(), end_addr);
3081 }
3082
3083 // This test is necessary; if omitted, the pointer updates to a partial object
3084 // that crosses the dense prefix boundary could be overwritten.
3085 if (source() != destination()) {
3086 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3087 Copy::aligned_conjoint_words(source(), destination(), words);
3088 }
3089 update_state(words);
3090 }
3091
3092 void InstanceKlass::oop_pc_update_pointers(oop obj) {
3093 oop_oop_iterate_oop_maps<true>(obj, PSParallelCompact::adjust_pointer_closure());
3094 }
3095
3096 void InstanceMirrorKlass::oop_pc_update_pointers(oop obj) {
3097 InstanceKlass::oop_pc_update_pointers(obj);
3098
3099 oop_oop_iterate_statics<true>(obj, PSParallelCompact::adjust_pointer_closure());
3100 }
3101
3102 void InstanceClassLoaderKlass::oop_pc_update_pointers(oop obj) {
3103 InstanceKlass::oop_pc_update_pointers(obj);
3104 }
3105
3106 #ifdef ASSERT
3107 template <class T> static void trace_reference_gc(const char *s, oop obj,
3108 bool is_ephemeron,
3109 T* referent_addr,
3110 T* next_addr,
3111 T* discovered_addr,
3112 T* value_addr) {
3113 if(TraceReferenceGC && PrintGCDetails) {
3114 gclog_or_tty->print_cr("%s obj " PTR_FORMAT, s, p2i(obj));
3115 gclog_or_tty->print_cr(" referent_addr/* " PTR_FORMAT " / "
3116 PTR_FORMAT, p2i(referent_addr),
3117 referent_addr ? p2i(oopDesc::load_decode_heap_oop(referent_addr)) : NULL);
3118 gclog_or_tty->print_cr(" next_addr/* " PTR_FORMAT " / "
3119 PTR_FORMAT, p2i(next_addr),
3120 next_addr ? p2i(oopDesc::load_decode_heap_oop(next_addr)) : NULL);
3121 gclog_or_tty->print_cr(" discovered_addr/* " PTR_FORMAT " / "
3122 PTR_FORMAT, p2i(discovered_addr),
3123 discovered_addr ? p2i(oopDesc::load_decode_heap_oop(discovered_addr)) : NULL);
3124 if (is_ephemeron) {
3125 gclog_or_tty->print_cr(" value_addr/* " PTR_FORMAT " / "
3126 PTR_FORMAT, p2i(value_addr),
3127 value_addr ? p2i(oopDesc::load_decode_heap_oop(value_addr)) : NULL);
3128 }
3129 }
3130 }
3131 #endif
3132
3133 template <class T>
3134 static void oop_pc_update_pointers_specialized(oop obj, InstanceRefKlass* klass) {
3135 T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj);
3136 PSParallelCompact::adjust_pointer(referent_addr);
3137 T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj);
3138 PSParallelCompact::adjust_pointer(next_addr);
3139 T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj);
3140 PSParallelCompact::adjust_pointer(discovered_addr);
3141 if (klass->reference_type() == REF_EPHEMERON) {
3142 T* value_addr = (T*)java_lang_ref_Ephemeron::value_addr(obj);
3143 PSParallelCompact::adjust_pointer(value_addr);
3144 debug_only(trace_reference_gc("InstanceRefKlass<Ephemeron>::oop_update_ptrs", obj, true,
3145 referent_addr, next_addr, discovered_addr, value_addr);)
3146 } else {
3147 debug_only(trace_reference_gc("InstanceRefKlass::oop_update_ptrs", obj, false,
3148 referent_addr, next_addr, discovered_addr, (T*)NULL);)
3149 }
3150 }
3151
3152 void InstanceRefKlass::oop_pc_update_pointers(oop obj) {
3153 InstanceKlass::oop_pc_update_pointers(obj);
3154
3155 if (UseCompressedOops) {
3156 oop_pc_update_pointers_specialized<narrowOop>(obj, this);
3157 } else {
3158 oop_pc_update_pointers_specialized<oop>(obj, this);
3159 }
3160 }
3161
3162 void ObjArrayKlass::oop_pc_update_pointers(oop obj) {
3163 assert(obj->is_objArray(), "obj must be obj array");
3164 oop_oop_iterate_elements<true>(objArrayOop(obj), PSParallelCompact::adjust_pointer_closure());
3165 }
3166
3167 void TypeArrayKlass::oop_pc_update_pointers(oop obj) {
3168 assert(obj->is_typeArray(),"must be a type array");
3169 }
3170
3171 ParMarkBitMapClosure::IterationStatus
3172 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3173 assert(destination() != NULL, "sanity");
3174 assert(bitmap()->obj_size(addr) == words, "bad size");
3175
3176 _source = addr;
3177 assert(PSParallelCompact::summary_data().calc_new_pointer(source()) ==
3178 destination(), "wrong destination");
3179
3180 if (words > words_remaining()) {
3181 return ParMarkBitMap::would_overflow;
3182 }
3183
3184 // The start_array must be updated even if the object is not moving.
3185 if (_start_array != NULL) {
3186 _start_array->allocate_block(destination());
3187 }
3188
3189 if (destination() != source()) {
3190 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3191 Copy::aligned_conjoint_words(source(), destination(), words);
3192 }
3193
3194 oop moved_oop = (oop) destination();
3195 compaction_manager()->update_contents(moved_oop);
3196 assert(moved_oop->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop));
3197
3198 update_state(words);
3199 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3200 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3201 }
3202
3203 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3204 ParCompactionManager* cm,
3205 PSParallelCompact::SpaceId space_id) :
3206 ParMarkBitMapClosure(mbm, cm),
3207 _space_id(space_id),
3208 _start_array(PSParallelCompact::start_array(space_id))
3209 {
3210 }
3211
3212 // Updates the references in the object to their new values.
3213 ParMarkBitMapClosure::IterationStatus
3214 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3215 do_addr(addr);
3216 return ParMarkBitMap::incomplete;
3217 }