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/systemDictionary.hpp"
28 #include "code/codeCache.hpp"
29 #include "gc/parallel/gcTaskManager.hpp"
30 #include "gc/parallel/parallelScavengeHeap.inline.hpp"
31 #include "gc/parallel/pcTasks.hpp"
32 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
33 #include "gc/parallel/psCompactionManager.inline.hpp"
34 #include "gc/parallel/psMarkSweep.hpp"
35 #include "gc/parallel/psMarkSweepDecorator.hpp"
36 #include "gc/parallel/psOldGen.hpp"
37 #include "gc/parallel/psParallelCompact.inline.hpp"
38 #include "gc/parallel/psPromotionManager.inline.hpp"
39 #include "gc/parallel/psScavenge.hpp"
40 #include "gc/parallel/psYoungGen.hpp"
41 #include "gc/shared/gcCause.hpp"
42 #include "gc/shared/gcHeapSummary.hpp"
43 #include "gc/shared/gcId.hpp"
44 #include "gc/shared/gcLocker.inline.hpp"
45 #include "gc/shared/gcTimer.hpp"
46 #include "gc/shared/gcTrace.hpp"
47 #include "gc/shared/gcTraceTime.hpp"
48 #include "gc/shared/isGCActiveMark.hpp"
49 #include "gc/shared/referencePolicy.hpp"
50 #include "gc/shared/referenceProcessor.hpp"
51 #include "gc/shared/spaceDecorator.hpp"
52 #include "oops/instanceKlass.inline.hpp"
53 #include "oops/instanceMirrorKlass.inline.hpp"
54 #include "oops/methodData.hpp"
55 #include "oops/objArrayKlass.inline.hpp"
56 #include "oops/oop.inline.hpp"
57 #include "runtime/atomic.inline.hpp"
58 #include "runtime/fprofiler.hpp"
59 #include "runtime/safepoint.hpp"
60 #include "runtime/vmThread.hpp"
61 #include "services/management.hpp"
62 #include "services/memTracker.hpp"
63 #include "services/memoryService.hpp"
64 #include "utilities/events.hpp"
65 #include "utilities/stack.inline.hpp"
66
67 #include <math.h>
68
69 // All sizes are in HeapWords.
70 const size_t ParallelCompactData::Log2RegionSize = 16; // 64K words
71 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
72 const size_t ParallelCompactData::RegionSizeBytes =
73 RegionSize << LogHeapWordSize;
74 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
75 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
76 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
77
78 const size_t ParallelCompactData::Log2BlockSize = 7; // 128 words
79 const size_t ParallelCompactData::BlockSize = (size_t)1 << Log2BlockSize;
80 const size_t ParallelCompactData::BlockSizeBytes =
81 BlockSize << LogHeapWordSize;
82 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1;
83 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1;
84 const size_t ParallelCompactData::BlockAddrMask = ~BlockAddrOffsetMask;
85
86 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
87 const size_t ParallelCompactData::Log2BlocksPerRegion =
88 Log2RegionSize - Log2BlockSize;
89
90 const ParallelCompactData::RegionData::region_sz_t
91 ParallelCompactData::RegionData::dc_shift = 27;
92
93 const ParallelCompactData::RegionData::region_sz_t
94 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
95
96 const ParallelCompactData::RegionData::region_sz_t
97 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
98
99 const ParallelCompactData::RegionData::region_sz_t
100 ParallelCompactData::RegionData::los_mask = ~dc_mask;
101
102 const ParallelCompactData::RegionData::region_sz_t
103 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
104
105 const ParallelCompactData::RegionData::region_sz_t
106 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
107
108 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
109 bool PSParallelCompact::_print_phases = false;
110
111 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
112
113 double PSParallelCompact::_dwl_mean;
114 double PSParallelCompact::_dwl_std_dev;
115 double PSParallelCompact::_dwl_first_term;
116 double PSParallelCompact::_dwl_adjustment;
117 #ifdef ASSERT
118 bool PSParallelCompact::_dwl_initialized = false;
119 #endif // #ifdef ASSERT
120
121 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
122 HeapWord* destination)
123 {
124 assert(src_region_idx != 0, "invalid src_region_idx");
125 assert(partial_obj_size != 0, "invalid partial_obj_size argument");
126 assert(destination != NULL, "invalid destination argument");
127
128 _src_region_idx = src_region_idx;
129 _partial_obj_size = partial_obj_size;
130 _destination = destination;
131
132 // These fields may not be updated below, so make sure they're clear.
133 assert(_dest_region_addr == NULL, "should have been cleared");
134 assert(_first_src_addr == NULL, "should have been cleared");
135
136 // Determine the number of destination regions for the partial object.
137 HeapWord* const last_word = destination + partial_obj_size - 1;
138 const ParallelCompactData& sd = PSParallelCompact::summary_data();
139 HeapWord* const beg_region_addr = sd.region_align_down(destination);
140 HeapWord* const end_region_addr = sd.region_align_down(last_word);
141
142 if (beg_region_addr == end_region_addr) {
143 // One destination region.
144 _destination_count = 1;
145 if (end_region_addr == destination) {
146 // The destination falls on a region boundary, thus the first word of the
147 // partial object will be the first word copied to the destination region.
148 _dest_region_addr = end_region_addr;
149 _first_src_addr = sd.region_to_addr(src_region_idx);
150 }
151 } else {
152 // Two destination regions. When copied, the partial object will cross a
153 // destination region boundary, so a word somewhere within the partial
154 // object will be the first word copied to the second destination region.
155 _destination_count = 2;
156 _dest_region_addr = end_region_addr;
157 const size_t ofs = pointer_delta(end_region_addr, destination);
158 assert(ofs < _partial_obj_size, "sanity");
159 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
160 }
161 }
162
163 void SplitInfo::clear()
164 {
165 _src_region_idx = 0;
166 _partial_obj_size = 0;
167 _destination = NULL;
168 _destination_count = 0;
169 _dest_region_addr = NULL;
170 _first_src_addr = NULL;
171 assert(!is_valid(), "sanity");
172 }
173
174 #ifdef ASSERT
175 void SplitInfo::verify_clear()
176 {
177 assert(_src_region_idx == 0, "not clear");
178 assert(_partial_obj_size == 0, "not clear");
179 assert(_destination == NULL, "not clear");
180 assert(_destination_count == 0, "not clear");
181 assert(_dest_region_addr == NULL, "not clear");
182 assert(_first_src_addr == NULL, "not clear");
183 }
184 #endif // #ifdef ASSERT
185
186
187 void PSParallelCompact::print_on_error(outputStream* st) {
188 _mark_bitmap.print_on_error(st);
189 }
190
191 #ifndef PRODUCT
192 const char* PSParallelCompact::space_names[] = {
193 "old ", "eden", "from", "to "
194 };
195
196 void PSParallelCompact::print_region_ranges()
197 {
198 tty->print_cr("space bottom top end new_top");
199 tty->print_cr("------ ---------- ---------- ---------- ----------");
200
201 for (unsigned int id = 0; id < last_space_id; ++id) {
202 const MutableSpace* space = _space_info[id].space();
203 tty->print_cr("%u %s "
204 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
205 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
206 id, space_names[id],
207 summary_data().addr_to_region_idx(space->bottom()),
208 summary_data().addr_to_region_idx(space->top()),
209 summary_data().addr_to_region_idx(space->end()),
210 summary_data().addr_to_region_idx(_space_info[id].new_top()));
211 }
212 }
213
214 void
215 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
216 {
217 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7)
218 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5)
219
220 ParallelCompactData& sd = PSParallelCompact::summary_data();
221 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
222 tty->print_cr(REGION_IDX_FORMAT " " PTR_FORMAT " "
223 REGION_IDX_FORMAT " " PTR_FORMAT " "
224 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
225 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
226 i, p2i(c->data_location()), dci, p2i(c->destination()),
227 c->partial_obj_size(), c->live_obj_size(),
228 c->data_size(), c->source_region(), c->destination_count());
229
230 #undef REGION_IDX_FORMAT
231 #undef REGION_DATA_FORMAT
232 }
233
234 void
235 print_generic_summary_data(ParallelCompactData& summary_data,
236 HeapWord* const beg_addr,
237 HeapWord* const end_addr)
238 {
239 size_t total_words = 0;
240 size_t i = summary_data.addr_to_region_idx(beg_addr);
241 const size_t last = summary_data.addr_to_region_idx(end_addr);
242 HeapWord* pdest = 0;
243
244 while (i <= last) {
245 ParallelCompactData::RegionData* c = summary_data.region(i);
246 if (c->data_size() != 0 || c->destination() != pdest) {
247 print_generic_summary_region(i, c);
248 total_words += c->data_size();
249 pdest = c->destination();
250 }
251 ++i;
252 }
253
254 tty->print_cr("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
255 }
256
257 void
258 print_generic_summary_data(ParallelCompactData& summary_data,
259 SpaceInfo* space_info)
260 {
261 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
262 const MutableSpace* space = space_info[id].space();
263 print_generic_summary_data(summary_data, space->bottom(),
264 MAX2(space->top(), space_info[id].new_top()));
265 }
266 }
267
268 void
269 print_initial_summary_region(size_t i,
270 const ParallelCompactData::RegionData* c,
271 bool newline = true)
272 {
273 tty->print(SIZE_FORMAT_W(5) " " PTR_FORMAT " "
274 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " "
275 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
276 i, p2i(c->destination()),
277 c->partial_obj_size(), c->live_obj_size(),
278 c->data_size(), c->source_region(), c->destination_count());
279 if (newline) tty->cr();
280 }
281
282 void
283 print_initial_summary_data(ParallelCompactData& summary_data,
284 const MutableSpace* space) {
285 if (space->top() == space->bottom()) {
286 return;
287 }
288
289 const size_t region_size = ParallelCompactData::RegionSize;
290 typedef ParallelCompactData::RegionData RegionData;
291 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
292 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
293 const RegionData* c = summary_data.region(end_region - 1);
294 HeapWord* end_addr = c->destination() + c->data_size();
295 const size_t live_in_space = pointer_delta(end_addr, space->bottom());
296
297 // Print (and count) the full regions at the beginning of the space.
298 size_t full_region_count = 0;
299 size_t i = summary_data.addr_to_region_idx(space->bottom());
300 while (i < end_region && summary_data.region(i)->data_size() == region_size) {
301 print_initial_summary_region(i, summary_data.region(i));
302 ++full_region_count;
303 ++i;
304 }
305
306 size_t live_to_right = live_in_space - full_region_count * region_size;
307
308 double max_reclaimed_ratio = 0.0;
309 size_t max_reclaimed_ratio_region = 0;
310 size_t max_dead_to_right = 0;
311 size_t max_live_to_right = 0;
312
313 // Print the 'reclaimed ratio' for regions while there is something live in
314 // the region or to the right of it. The remaining regions are empty (and
315 // uninteresting), and computing the ratio will result in division by 0.
316 while (i < end_region && live_to_right > 0) {
317 c = summary_data.region(i);
318 HeapWord* const region_addr = summary_data.region_to_addr(i);
319 const size_t used_to_right = pointer_delta(space->top(), region_addr);
320 const size_t dead_to_right = used_to_right - live_to_right;
321 const double reclaimed_ratio = double(dead_to_right) / live_to_right;
322
323 if (reclaimed_ratio > max_reclaimed_ratio) {
324 max_reclaimed_ratio = reclaimed_ratio;
325 max_reclaimed_ratio_region = i;
326 max_dead_to_right = dead_to_right;
327 max_live_to_right = live_to_right;
328 }
329
330 print_initial_summary_region(i, c, false);
331 tty->print_cr(" %12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
332 reclaimed_ratio, dead_to_right, live_to_right);
333
334 live_to_right -= c->data_size();
335 ++i;
336 }
337
338 // Any remaining regions are empty. Print one more if there is one.
339 if (i < end_region) {
340 print_initial_summary_region(i, summary_data.region(i));
341 }
342
343 tty->print_cr("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " "
344 "l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
345 max_reclaimed_ratio_region, max_dead_to_right,
346 max_live_to_right, max_reclaimed_ratio);
347 }
348
349 void
350 print_initial_summary_data(ParallelCompactData& summary_data,
351 SpaceInfo* space_info) {
352 unsigned int id = PSParallelCompact::old_space_id;
353 const MutableSpace* space;
354 do {
355 space = space_info[id].space();
356 print_initial_summary_data(summary_data, space);
357 } while (++id < PSParallelCompact::eden_space_id);
358
359 do {
360 space = space_info[id].space();
361 print_generic_summary_data(summary_data, space->bottom(), space->top());
362 } while (++id < PSParallelCompact::last_space_id);
363 }
364 #endif // #ifndef PRODUCT
365
366 #ifdef ASSERT
367 size_t add_obj_count;
368 size_t add_obj_size;
369 size_t mark_bitmap_count;
370 size_t mark_bitmap_size;
371 #endif // #ifdef ASSERT
372
373 ParallelCompactData::ParallelCompactData()
374 {
375 _region_start = 0;
376
377 _region_vspace = 0;
378 _reserved_byte_size = 0;
379 _region_data = 0;
380 _region_count = 0;
381
382 _block_vspace = 0;
383 _block_data = 0;
384 _block_count = 0;
385 }
386
387 bool ParallelCompactData::initialize(MemRegion covered_region)
388 {
389 _region_start = covered_region.start();
390 const size_t region_size = covered_region.word_size();
391 DEBUG_ONLY(_region_end = _region_start + region_size;)
392
393 assert(region_align_down(_region_start) == _region_start,
394 "region start not aligned");
395 assert((region_size & RegionSizeOffsetMask) == 0,
396 "region size not a multiple of RegionSize");
397
398 bool result = initialize_region_data(region_size) && initialize_block_data();
399 return result;
400 }
401
402 PSVirtualSpace*
403 ParallelCompactData::create_vspace(size_t count, size_t element_size)
404 {
405 const size_t raw_bytes = count * element_size;
406 const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
407 const size_t granularity = os::vm_allocation_granularity();
408 _reserved_byte_size = align_size_up(raw_bytes, MAX2(page_sz, granularity));
409
410 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
411 MAX2(page_sz, granularity);
412 ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0);
413 os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(),
414 rs.size());
415
416 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
417
418 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
419 if (vspace != 0) {
420 if (vspace->expand_by(_reserved_byte_size)) {
421 return vspace;
422 }
423 delete vspace;
424 // Release memory reserved in the space.
425 rs.release();
426 }
427
428 return 0;
429 }
430
431 bool ParallelCompactData::initialize_region_data(size_t region_size)
432 {
433 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
434 _region_vspace = create_vspace(count, sizeof(RegionData));
435 if (_region_vspace != 0) {
436 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
437 _region_count = count;
438 return true;
439 }
440 return false;
441 }
442
443 bool ParallelCompactData::initialize_block_data()
444 {
445 assert(_region_count != 0, "region data must be initialized first");
446 const size_t count = _region_count << Log2BlocksPerRegion;
447 _block_vspace = create_vspace(count, sizeof(BlockData));
448 if (_block_vspace != 0) {
449 _block_data = (BlockData*)_block_vspace->reserved_low_addr();
450 _block_count = count;
451 return true;
452 }
453 return false;
454 }
455
456 void ParallelCompactData::clear()
457 {
458 memset(_region_data, 0, _region_vspace->committed_size());
459 memset(_block_data, 0, _block_vspace->committed_size());
460 }
461
462 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
463 assert(beg_region <= _region_count, "beg_region out of range");
464 assert(end_region <= _region_count, "end_region out of range");
465 assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize");
466
467 const size_t region_cnt = end_region - beg_region;
468 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
469
470 const size_t beg_block = beg_region * BlocksPerRegion;
471 const size_t block_cnt = region_cnt * BlocksPerRegion;
472 memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));
473 }
474
475 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
476 {
477 const RegionData* cur_cp = region(region_idx);
478 const RegionData* const end_cp = region(region_count() - 1);
479
480 HeapWord* result = region_to_addr(region_idx);
481 if (cur_cp < end_cp) {
482 do {
483 result += cur_cp->partial_obj_size();
484 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
485 }
486 return result;
487 }
488
489 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
490 {
491 const size_t obj_ofs = pointer_delta(addr, _region_start);
492 const size_t beg_region = obj_ofs >> Log2RegionSize;
493 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
494
495 DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
496 DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
497
498 if (beg_region == end_region) {
499 // All in one region.
500 _region_data[beg_region].add_live_obj(len);
501 return;
502 }
503
504 // First region.
505 const size_t beg_ofs = region_offset(addr);
506 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
507
508 Klass* klass = ((oop)addr)->klass();
509 // Middle regions--completely spanned by this object.
510 for (size_t region = beg_region + 1; region < end_region; ++region) {
511 _region_data[region].set_partial_obj_size(RegionSize);
512 _region_data[region].set_partial_obj_addr(addr);
513 }
514
515 // Last region.
516 const size_t end_ofs = region_offset(addr + len - 1);
517 _region_data[end_region].set_partial_obj_size(end_ofs + 1);
518 _region_data[end_region].set_partial_obj_addr(addr);
519 }
520
521 void
522 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
523 {
524 assert(region_offset(beg) == 0, "not RegionSize aligned");
525 assert(region_offset(end) == 0, "not RegionSize aligned");
526
527 size_t cur_region = addr_to_region_idx(beg);
528 const size_t end_region = addr_to_region_idx(end);
529 HeapWord* addr = beg;
530 while (cur_region < end_region) {
531 _region_data[cur_region].set_destination(addr);
532 _region_data[cur_region].set_destination_count(0);
533 _region_data[cur_region].set_source_region(cur_region);
534 _region_data[cur_region].set_data_location(addr);
535
536 // Update live_obj_size so the region appears completely full.
537 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
538 _region_data[cur_region].set_live_obj_size(live_size);
539
540 ++cur_region;
541 addr += RegionSize;
542 }
543 }
544
545 // Find the point at which a space can be split and, if necessary, record the
546 // split point.
547 //
548 // If the current src region (which overflowed the destination space) doesn't
549 // have a partial object, the split point is at the beginning of the current src
550 // region (an "easy" split, no extra bookkeeping required).
551 //
552 // If the current src region has a partial object, the split point is in the
553 // region where that partial object starts (call it the split_region). If
554 // split_region has a partial object, then the split point is just after that
555 // partial object (a "hard" split where we have to record the split data and
556 // zero the partial_obj_size field). With a "hard" split, we know that the
557 // partial_obj ends within split_region because the partial object that caused
558 // the overflow starts in split_region. If split_region doesn't have a partial
559 // obj, then the split is at the beginning of split_region (another "easy"
560 // split).
561 HeapWord*
562 ParallelCompactData::summarize_split_space(size_t src_region,
563 SplitInfo& split_info,
564 HeapWord* destination,
565 HeapWord* target_end,
566 HeapWord** target_next)
567 {
568 assert(destination <= target_end, "sanity");
569 assert(destination + _region_data[src_region].data_size() > target_end,
570 "region should not fit into target space");
571 assert(is_region_aligned(target_end), "sanity");
572
573 size_t split_region = src_region;
574 HeapWord* split_destination = destination;
575 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
576
577 if (destination + partial_obj_size > target_end) {
578 // The split point is just after the partial object (if any) in the
579 // src_region that contains the start of the object that overflowed the
580 // destination space.
581 //
582 // Find the start of the "overflow" object and set split_region to the
583 // region containing it.
584 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
585 split_region = addr_to_region_idx(overflow_obj);
586
587 // Clear the source_region field of all destination regions whose first word
588 // came from data after the split point (a non-null source_region field
589 // implies a region must be filled).
590 //
591 // An alternative to the simple loop below: clear during post_compact(),
592 // which uses memcpy instead of individual stores, and is easy to
593 // parallelize. (The downside is that it clears the entire RegionData
594 // object as opposed to just one field.)
595 //
596 // post_compact() would have to clear the summary data up to the highest
597 // address that was written during the summary phase, which would be
598 //
599 // max(top, max(new_top, clear_top))
600 //
601 // where clear_top is a new field in SpaceInfo. Would have to set clear_top
602 // to target_end.
603 const RegionData* const sr = region(split_region);
604 const size_t beg_idx =
605 addr_to_region_idx(region_align_up(sr->destination() +
606 sr->partial_obj_size()));
607 const size_t end_idx = addr_to_region_idx(target_end);
608
609 if (TraceParallelOldGCSummaryPhase) {
610 gclog_or_tty->print_cr("split: clearing source_region field in ["
611 SIZE_FORMAT ", " SIZE_FORMAT ")",
612 beg_idx, end_idx);
613 }
614 for (size_t idx = beg_idx; idx < end_idx; ++idx) {
615 _region_data[idx].set_source_region(0);
616 }
617
618 // Set split_destination and partial_obj_size to reflect the split region.
619 split_destination = sr->destination();
620 partial_obj_size = sr->partial_obj_size();
621 }
622
623 // The split is recorded only if a partial object extends onto the region.
624 if (partial_obj_size != 0) {
625 _region_data[split_region].set_partial_obj_size(0);
626 split_info.record(split_region, partial_obj_size, split_destination);
627 }
628
629 // Setup the continuation addresses.
630 *target_next = split_destination + partial_obj_size;
631 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
632
633 if (TraceParallelOldGCSummaryPhase) {
634 const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
635 gclog_or_tty->print_cr("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT
636 " pos=" SIZE_FORMAT,
637 split_type, p2i(source_next), split_region,
638 partial_obj_size);
639 gclog_or_tty->print_cr("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT
640 " tn=" PTR_FORMAT,
641 split_type, p2i(split_destination),
642 addr_to_region_idx(split_destination),
643 p2i(*target_next));
644
645 if (partial_obj_size != 0) {
646 HeapWord* const po_beg = split_info.destination();
647 HeapWord* const po_end = po_beg + split_info.partial_obj_size();
648 gclog_or_tty->print_cr("%s split: "
649 "po_beg=" PTR_FORMAT " " SIZE_FORMAT " "
650 "po_end=" PTR_FORMAT " " SIZE_FORMAT,
651 split_type,
652 p2i(po_beg), addr_to_region_idx(po_beg),
653 p2i(po_end), addr_to_region_idx(po_end));
654 }
655 }
656
657 return source_next;
658 }
659
660 bool ParallelCompactData::summarize(SplitInfo& split_info,
661 HeapWord* source_beg, HeapWord* source_end,
662 HeapWord** source_next,
663 HeapWord* target_beg, HeapWord* target_end,
664 HeapWord** target_next)
665 {
666 if (TraceParallelOldGCSummaryPhase) {
667 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
668 tty->print_cr("sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
669 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
670 p2i(source_beg), p2i(source_end), p2i(source_next_val),
671 p2i(target_beg), p2i(target_end), p2i(*target_next));
672 }
673
674 size_t cur_region = addr_to_region_idx(source_beg);
675 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
676
677 HeapWord *dest_addr = target_beg;
678 while (cur_region < end_region) {
679 // The destination must be set even if the region has no data.
680 _region_data[cur_region].set_destination(dest_addr);
681
682 size_t words = _region_data[cur_region].data_size();
683 if (words > 0) {
684 // If cur_region does not fit entirely into the target space, find a point
685 // at which the source space can be 'split' so that part is copied to the
686 // target space and the rest is copied elsewhere.
687 if (dest_addr + words > target_end) {
688 assert(source_next != NULL, "source_next is NULL when splitting");
689 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
690 target_end, target_next);
691 return false;
692 }
693
694 // Compute the destination_count for cur_region, and if necessary, update
695 // source_region for a destination region. The source_region field is
696 // updated if cur_region is the first (left-most) region to be copied to a
697 // destination region.
698 //
699 // The destination_count calculation is a bit subtle. A region that has
700 // data that compacts into itself does not count itself as a destination.
701 // This maintains the invariant that a zero count means the region is
702 // available and can be claimed and then filled.
703 uint destination_count = 0;
704 if (split_info.is_split(cur_region)) {
705 // The current region has been split: the partial object will be copied
706 // to one destination space and the remaining data will be copied to
707 // another destination space. Adjust the initial destination_count and,
708 // if necessary, set the source_region field if the partial object will
709 // cross a destination region boundary.
710 destination_count = split_info.destination_count();
711 if (destination_count == 2) {
712 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
713 _region_data[dest_idx].set_source_region(cur_region);
714 }
715 }
716
717 HeapWord* const last_addr = dest_addr + words - 1;
718 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
719 const size_t dest_region_2 = addr_to_region_idx(last_addr);
720
721 // Initially assume that the destination regions will be the same and
722 // adjust the value below if necessary. Under this assumption, if
723 // cur_region == dest_region_2, then cur_region will be compacted
724 // completely into itself.
725 destination_count += cur_region == dest_region_2 ? 0 : 1;
726 if (dest_region_1 != dest_region_2) {
727 // Destination regions differ; adjust destination_count.
728 destination_count += 1;
729 // Data from cur_region will be copied to the start of dest_region_2.
730 _region_data[dest_region_2].set_source_region(cur_region);
731 } else if (region_offset(dest_addr) == 0) {
732 // Data from cur_region will be copied to the start of the destination
733 // region.
734 _region_data[dest_region_1].set_source_region(cur_region);
735 }
736
737 _region_data[cur_region].set_destination_count(destination_count);
738 _region_data[cur_region].set_data_location(region_to_addr(cur_region));
739 dest_addr += words;
740 }
741
742 ++cur_region;
743 }
744
745 *target_next = dest_addr;
746 return true;
747 }
748
749 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) {
750 assert(addr != NULL, "Should detect NULL oop earlier");
751 assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap");
752 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked");
753
754 // Region covering the object.
755 RegionData* const region_ptr = addr_to_region_ptr(addr);
756 HeapWord* result = region_ptr->destination();
757
758 // If the entire Region is live, the new location is region->destination + the
759 // offset of the object within in the Region.
760
761 // Run some performance tests to determine if this special case pays off. It
762 // is worth it for pointers into the dense prefix. If the optimization to
763 // avoid pointer updates in regions that only point to the dense prefix is
764 // ever implemented, this should be revisited.
765 if (region_ptr->data_size() == RegionSize) {
766 result += region_offset(addr);
767 return result;
768 }
769
770 // Otherwise, the new location is region->destination + block offset + the
771 // number of live words in the Block that are (a) to the left of addr and (b)
772 // due to objects that start in the Block.
773
774 // Fill in the block table if necessary. This is unsynchronized, so multiple
775 // threads may fill the block table for a region (harmless, since it is
776 // idempotent).
777 if (!region_ptr->blocks_filled()) {
778 PSParallelCompact::fill_blocks(addr_to_region_idx(addr));
779 region_ptr->set_blocks_filled();
780 }
781
782 HeapWord* const search_start = block_align_down(addr);
783 const size_t block_offset = addr_to_block_ptr(addr)->offset();
784
785 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
786 const size_t live = bitmap->live_words_in_range(search_start, oop(addr));
787 result += block_offset + live;
788 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result));
789 return result;
790 }
791
792 #ifdef ASSERT
793 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
794 {
795 const size_t* const beg = (const size_t*)vspace->committed_low_addr();
796 const size_t* const end = (const size_t*)vspace->committed_high_addr();
797 for (const size_t* p = beg; p < end; ++p) {
798 assert(*p == 0, "not zero");
799 }
800 }
801
802 void ParallelCompactData::verify_clear()
803 {
804 verify_clear(_region_vspace);
805 verify_clear(_block_vspace);
806 }
807 #endif // #ifdef ASSERT
808
809 STWGCTimer PSParallelCompact::_gc_timer;
810 ParallelOldTracer PSParallelCompact::_gc_tracer;
811 elapsedTimer PSParallelCompact::_accumulated_time;
812 unsigned int PSParallelCompact::_total_invocations = 0;
813 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
814 jlong PSParallelCompact::_time_of_last_gc = 0;
815 CollectorCounters* PSParallelCompact::_counters = NULL;
816 ParMarkBitMap PSParallelCompact::_mark_bitmap;
817 ParallelCompactData PSParallelCompact::_summary_data;
818
819 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
820
821 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
822
823 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_pointer_closure;
824 PSParallelCompact::AdjustKlassClosure PSParallelCompact::_adjust_klass_closure;
825
826 void PSParallelCompact::AdjustKlassClosure::do_klass(Klass* klass) {
827 klass->oops_do(&PSParallelCompact::_adjust_pointer_closure);
828 }
829
830 void PSParallelCompact::post_initialize() {
831 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
832 MemRegion mr = heap->reserved_region();
833 _ref_processor =
834 new ReferenceProcessor(mr, // span
835 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
836 ParallelGCThreads, // mt processing degree
837 true, // mt discovery
838 ParallelGCThreads, // mt discovery degree
839 true, // atomic_discovery
840 &_is_alive_closure); // non-header is alive closure
841 _counters = new CollectorCounters("PSParallelCompact", 1);
842
843 // Initialize static fields in ParCompactionManager.
844 ParCompactionManager::initialize(mark_bitmap());
845 }
846
847 bool PSParallelCompact::initialize() {
848 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
849 MemRegion mr = heap->reserved_region();
850
851 // Was the old gen get allocated successfully?
852 if (!heap->old_gen()->is_allocated()) {
853 return false;
854 }
855
856 initialize_space_info();
857 initialize_dead_wood_limiter();
858
859 if (!_mark_bitmap.initialize(mr)) {
860 vm_shutdown_during_initialization(
861 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
862 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
863 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
864 return false;
865 }
866
867 if (!_summary_data.initialize(mr)) {
868 vm_shutdown_during_initialization(
869 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
870 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
871 _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
872 return false;
873 }
874
875 return true;
876 }
877
878 void PSParallelCompact::initialize_space_info()
879 {
880 memset(&_space_info, 0, sizeof(_space_info));
881
882 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
883 PSYoungGen* young_gen = heap->young_gen();
884
885 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
886 _space_info[eden_space_id].set_space(young_gen->eden_space());
887 _space_info[from_space_id].set_space(young_gen->from_space());
888 _space_info[to_space_id].set_space(young_gen->to_space());
889
890 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
891 }
892
893 void PSParallelCompact::initialize_dead_wood_limiter()
894 {
895 const size_t max = 100;
896 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
897 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
898 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
899 DEBUG_ONLY(_dwl_initialized = true;)
900 _dwl_adjustment = normal_distribution(1.0);
901 }
902
903 // Simple class for storing info about the heap at the start of GC, to be used
904 // after GC for comparison/printing.
905 class PreGCValues {
906 public:
907 PreGCValues() { }
908 PreGCValues(ParallelScavengeHeap* heap) { fill(heap); }
909
910 void fill(ParallelScavengeHeap* heap) {
911 _heap_used = heap->used();
912 _young_gen_used = heap->young_gen()->used_in_bytes();
913 _old_gen_used = heap->old_gen()->used_in_bytes();
914 _metadata_used = MetaspaceAux::used_bytes();
915 };
916
917 size_t heap_used() const { return _heap_used; }
918 size_t young_gen_used() const { return _young_gen_used; }
919 size_t old_gen_used() const { return _old_gen_used; }
920 size_t metadata_used() const { return _metadata_used; }
921
922 private:
923 size_t _heap_used;
924 size_t _young_gen_used;
925 size_t _old_gen_used;
926 size_t _metadata_used;
927 };
928
929 void
930 PSParallelCompact::clear_data_covering_space(SpaceId id)
931 {
932 // At this point, top is the value before GC, new_top() is the value that will
933 // be set at the end of GC. The marking bitmap is cleared to top; nothing
934 // should be marked above top. The summary data is cleared to the larger of
935 // top & new_top.
936 MutableSpace* const space = _space_info[id].space();
937 HeapWord* const bot = space->bottom();
938 HeapWord* const top = space->top();
939 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
940
941 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
942 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
943 _mark_bitmap.clear_range(beg_bit, end_bit);
944
945 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
946 const size_t end_region =
947 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
948 _summary_data.clear_range(beg_region, end_region);
949
950 // Clear the data used to 'split' regions.
951 SplitInfo& split_info = _space_info[id].split_info();
952 if (split_info.is_valid()) {
953 split_info.clear();
954 }
955 DEBUG_ONLY(split_info.verify_clear();)
956 }
957
958 void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values)
959 {
960 // Update the from & to space pointers in space_info, since they are swapped
961 // at each young gen gc. Do the update unconditionally (even though a
962 // promotion failure does not swap spaces) because an unknown number of young
963 // collections will have swapped the spaces an unknown number of times.
964 GCTraceTime tm("pre compact", print_phases(), true, &_gc_timer);
965 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
966 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
967 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
968
969 pre_gc_values->fill(heap);
970
971 DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
972 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
973
974 // Increment the invocation count
975 heap->increment_total_collections(true);
976
977 // We need to track unique mark sweep invocations as well.
978 _total_invocations++;
979
980 heap->print_heap_before_gc();
981 heap->trace_heap_before_gc(&_gc_tracer);
982
983 // Fill in TLABs
984 heap->accumulate_statistics_all_tlabs();
985 heap->ensure_parsability(true); // retire TLABs
986
987 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
988 HandleMark hm; // Discard invalid handles created during verification
989 Universe::verify(" VerifyBeforeGC:");
990 }
991
992 // Verify object start arrays
993 if (VerifyObjectStartArray &&
994 VerifyBeforeGC) {
995 heap->old_gen()->verify_object_start_array();
996 }
997
998 DEBUG_ONLY(mark_bitmap()->verify_clear();)
999 DEBUG_ONLY(summary_data().verify_clear();)
1000
1001 // Have worker threads release resources the next time they run a task.
1002 gc_task_manager()->release_all_resources();
1003 }
1004
1005 void PSParallelCompact::post_compact()
1006 {
1007 GCTraceTime tm("post compact", print_phases(), true, &_gc_timer);
1008
1009 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1010 // Clear the marking bitmap, summary data and split info.
1011 clear_data_covering_space(SpaceId(id));
1012 // Update top(). Must be done after clearing the bitmap and summary data.
1013 _space_info[id].publish_new_top();
1014 }
1015
1016 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1017 MutableSpace* const from_space = _space_info[from_space_id].space();
1018 MutableSpace* const to_space = _space_info[to_space_id].space();
1019
1020 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1021 bool eden_empty = eden_space->is_empty();
1022 if (!eden_empty) {
1023 eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1024 heap->young_gen(), heap->old_gen());
1025 }
1026
1027 // Update heap occupancy information which is used as input to the soft ref
1028 // clearing policy at the next gc.
1029 Universe::update_heap_info_at_gc();
1030
1031 bool young_gen_empty = eden_empty && from_space->is_empty() &&
1032 to_space->is_empty();
1033
1034 ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set());
1035 MemRegion old_mr = heap->old_gen()->reserved();
1036 if (young_gen_empty) {
1037 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
1038 } else {
1039 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1040 }
1041
1042 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1043 ClassLoaderDataGraph::purge();
1044 MetaspaceAux::verify_metrics();
1045
1046 CodeCache::gc_epilogue();
1047 JvmtiExport::gc_epilogue();
1048
1049 #if defined(COMPILER2) || INCLUDE_JVMCI
1050 DerivedPointerTable::update_pointers();
1051 #endif
1052
1053 ref_processor()->enqueue_discovered_references(NULL);
1054
1055 if (ZapUnusedHeapArea) {
1056 heap->gen_mangle_unused_area();
1057 }
1058
1059 // Update time of last GC
1060 reset_millis_since_last_gc();
1061 }
1062
1063 HeapWord*
1064 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1065 bool maximum_compaction)
1066 {
1067 const size_t region_size = ParallelCompactData::RegionSize;
1068 const ParallelCompactData& sd = summary_data();
1069
1070 const MutableSpace* const space = _space_info[id].space();
1071 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1072 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1073 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1074
1075 // Skip full regions at the beginning of the space--they are necessarily part
1076 // of the dense prefix.
1077 size_t full_count = 0;
1078 const RegionData* cp;
1079 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1080 ++full_count;
1081 }
1082
1083 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1084 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1085 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1086 if (maximum_compaction || cp == end_cp || interval_ended) {
1087 _maximum_compaction_gc_num = total_invocations();
1088 return sd.region_to_addr(cp);
1089 }
1090
1091 HeapWord* const new_top = _space_info[id].new_top();
1092 const size_t space_live = pointer_delta(new_top, space->bottom());
1093 const size_t space_used = space->used_in_words();
1094 const size_t space_capacity = space->capacity_in_words();
1095
1096 const double cur_density = double(space_live) / space_capacity;
1097 const double deadwood_density =
1098 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1099 const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1100
1101 if (TraceParallelOldGCDensePrefix) {
1102 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1103 cur_density, deadwood_density, deadwood_goal);
1104 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1105 "space_cap=" SIZE_FORMAT,
1106 space_live, space_used,
1107 space_capacity);
1108 }
1109
1110 // XXX - Use binary search?
1111 HeapWord* dense_prefix = sd.region_to_addr(cp);
1112 const RegionData* full_cp = cp;
1113 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1114 while (cp < end_cp) {
1115 HeapWord* region_destination = cp->destination();
1116 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1117 if (TraceParallelOldGCDensePrefix && Verbose) {
1118 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1119 "dp=" PTR_FORMAT " " "cdw=" SIZE_FORMAT_W(8),
1120 sd.region(cp), p2i(region_destination),
1121 p2i(dense_prefix), cur_deadwood);
1122 }
1123
1124 if (cur_deadwood >= deadwood_goal) {
1125 // Found the region that has the correct amount of deadwood to the left.
1126 // This typically occurs after crossing a fairly sparse set of regions, so
1127 // iterate backwards over those sparse regions, looking for the region
1128 // that has the lowest density of live objects 'to the right.'
1129 size_t space_to_left = sd.region(cp) * region_size;
1130 size_t live_to_left = space_to_left - cur_deadwood;
1131 size_t space_to_right = space_capacity - space_to_left;
1132 size_t live_to_right = space_live - live_to_left;
1133 double density_to_right = double(live_to_right) / space_to_right;
1134 while (cp > full_cp) {
1135 --cp;
1136 const size_t prev_region_live_to_right = live_to_right -
1137 cp->data_size();
1138 const size_t prev_region_space_to_right = space_to_right + region_size;
1139 double prev_region_density_to_right =
1140 double(prev_region_live_to_right) / prev_region_space_to_right;
1141 if (density_to_right <= prev_region_density_to_right) {
1142 return dense_prefix;
1143 }
1144 if (TraceParallelOldGCDensePrefix && Verbose) {
1145 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1146 "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1147 prev_region_density_to_right);
1148 }
1149 dense_prefix -= region_size;
1150 live_to_right = prev_region_live_to_right;
1151 space_to_right = prev_region_space_to_right;
1152 density_to_right = prev_region_density_to_right;
1153 }
1154 return dense_prefix;
1155 }
1156
1157 dense_prefix += region_size;
1158 ++cp;
1159 }
1160
1161 return dense_prefix;
1162 }
1163
1164 #ifndef PRODUCT
1165 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1166 const SpaceId id,
1167 const bool maximum_compaction,
1168 HeapWord* const addr)
1169 {
1170 const size_t region_idx = summary_data().addr_to_region_idx(addr);
1171 RegionData* const cp = summary_data().region(region_idx);
1172 const MutableSpace* const space = _space_info[id].space();
1173 HeapWord* const new_top = _space_info[id].new_top();
1174
1175 const size_t space_live = pointer_delta(new_top, space->bottom());
1176 const size_t dead_to_left = pointer_delta(addr, cp->destination());
1177 const size_t space_cap = space->capacity_in_words();
1178 const double dead_to_left_pct = double(dead_to_left) / space_cap;
1179 const size_t live_to_right = new_top - cp->destination();
1180 const size_t dead_to_right = space->top() - addr - live_to_right;
1181
1182 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1183 "spl=" SIZE_FORMAT " "
1184 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1185 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1186 " ratio=%10.8f",
1187 algorithm, p2i(addr), region_idx,
1188 space_live,
1189 dead_to_left, dead_to_left_pct,
1190 dead_to_right, live_to_right,
1191 double(dead_to_right) / live_to_right);
1192 }
1193 #endif // #ifndef PRODUCT
1194
1195 // Return a fraction indicating how much of the generation can be treated as
1196 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution
1197 // based on the density of live objects in the generation to determine a limit,
1198 // which is then adjusted so the return value is min_percent when the density is
1199 // 1.
1200 //
1201 // The following table shows some return values for a different values of the
1202 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1203 // min_percent is 1.
1204 //
1205 // fraction allowed as dead wood
1206 // -----------------------------------------------------------------
1207 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1208 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1209 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1210 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1211 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1212 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1213 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1214 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1215 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1216 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1217 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1218 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1219 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1220 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1221 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1222 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1223 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1224 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1225 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1226 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1227 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1228 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1229 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1230
1231 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1232 {
1233 assert(_dwl_initialized, "uninitialized");
1234
1235 // The raw limit is the value of the normal distribution at x = density.
1236 const double raw_limit = normal_distribution(density);
1237
1238 // Adjust the raw limit so it becomes the minimum when the density is 1.
1239 //
1240 // First subtract the adjustment value (which is simply the precomputed value
1241 // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1242 // Then add the minimum value, so the minimum is returned when the density is
1243 // 1. Finally, prevent negative values, which occur when the mean is not 0.5.
1244 const double min = double(min_percent) / 100.0;
1245 const double limit = raw_limit - _dwl_adjustment + min;
1246 return MAX2(limit, 0.0);
1247 }
1248
1249 ParallelCompactData::RegionData*
1250 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1251 const RegionData* end)
1252 {
1253 const size_t region_size = ParallelCompactData::RegionSize;
1254 ParallelCompactData& sd = summary_data();
1255 size_t left = sd.region(beg);
1256 size_t right = end > beg ? sd.region(end) - 1 : left;
1257
1258 // Binary search.
1259 while (left < right) {
1260 // Equivalent to (left + right) / 2, but does not overflow.
1261 const size_t middle = left + (right - left) / 2;
1262 RegionData* const middle_ptr = sd.region(middle);
1263 HeapWord* const dest = middle_ptr->destination();
1264 HeapWord* const addr = sd.region_to_addr(middle);
1265 assert(dest != NULL, "sanity");
1266 assert(dest <= addr, "must move left");
1267
1268 if (middle > left && dest < addr) {
1269 right = middle - 1;
1270 } else if (middle < right && middle_ptr->data_size() == region_size) {
1271 left = middle + 1;
1272 } else {
1273 return middle_ptr;
1274 }
1275 }
1276 return sd.region(left);
1277 }
1278
1279 ParallelCompactData::RegionData*
1280 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1281 const RegionData* end,
1282 size_t dead_words)
1283 {
1284 ParallelCompactData& sd = summary_data();
1285 size_t left = sd.region(beg);
1286 size_t right = end > beg ? sd.region(end) - 1 : left;
1287
1288 // Binary search.
1289 while (left < right) {
1290 // Equivalent to (left + right) / 2, but does not overflow.
1291 const size_t middle = left + (right - left) / 2;
1292 RegionData* const middle_ptr = sd.region(middle);
1293 HeapWord* const dest = middle_ptr->destination();
1294 HeapWord* const addr = sd.region_to_addr(middle);
1295 assert(dest != NULL, "sanity");
1296 assert(dest <= addr, "must move left");
1297
1298 const size_t dead_to_left = pointer_delta(addr, dest);
1299 if (middle > left && dead_to_left > dead_words) {
1300 right = middle - 1;
1301 } else if (middle < right && dead_to_left < dead_words) {
1302 left = middle + 1;
1303 } else {
1304 return middle_ptr;
1305 }
1306 }
1307 return sd.region(left);
1308 }
1309
1310 // The result is valid during the summary phase, after the initial summarization
1311 // of each space into itself, and before final summarization.
1312 inline double
1313 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1314 HeapWord* const bottom,
1315 HeapWord* const top,
1316 HeapWord* const new_top)
1317 {
1318 ParallelCompactData& sd = summary_data();
1319
1320 assert(cp != NULL, "sanity");
1321 assert(bottom != NULL, "sanity");
1322 assert(top != NULL, "sanity");
1323 assert(new_top != NULL, "sanity");
1324 assert(top >= new_top, "summary data problem?");
1325 assert(new_top > bottom, "space is empty; should not be here");
1326 assert(new_top >= cp->destination(), "sanity");
1327 assert(top >= sd.region_to_addr(cp), "sanity");
1328
1329 HeapWord* const destination = cp->destination();
1330 const size_t dense_prefix_live = pointer_delta(destination, bottom);
1331 const size_t compacted_region_live = pointer_delta(new_top, destination);
1332 const size_t compacted_region_used = pointer_delta(top,
1333 sd.region_to_addr(cp));
1334 const size_t reclaimable = compacted_region_used - compacted_region_live;
1335
1336 const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1337 return double(reclaimable) / divisor;
1338 }
1339
1340 // Return the address of the end of the dense prefix, a.k.a. the start of the
1341 // compacted region. The address is always on a region boundary.
1342 //
1343 // Completely full regions at the left are skipped, since no compaction can
1344 // occur in those regions. Then the maximum amount of dead wood to allow is
1345 // computed, based on the density (amount live / capacity) of the generation;
1346 // the region with approximately that amount of dead space to the left is
1347 // identified as the limit region. Regions between the last completely full
1348 // region and the limit region are scanned and the one that has the best
1349 // (maximum) reclaimed_ratio() is selected.
1350 HeapWord*
1351 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1352 bool maximum_compaction)
1353 {
1354 const size_t region_size = ParallelCompactData::RegionSize;
1355 const ParallelCompactData& sd = summary_data();
1356
1357 const MutableSpace* const space = _space_info[id].space();
1358 HeapWord* const top = space->top();
1359 HeapWord* const top_aligned_up = sd.region_align_up(top);
1360 HeapWord* const new_top = _space_info[id].new_top();
1361 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1362 HeapWord* const bottom = space->bottom();
1363 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1364 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1365 const RegionData* const new_top_cp =
1366 sd.addr_to_region_ptr(new_top_aligned_up);
1367
1368 // Skip full regions at the beginning of the space--they are necessarily part
1369 // of the dense prefix.
1370 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1371 assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1372 space->is_empty(), "no dead space allowed to the left");
1373 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1374 "region must have dead space");
1375
1376 // The gc number is saved whenever a maximum compaction is done, and used to
1377 // determine when the maximum compaction interval has expired. This avoids
1378 // successive max compactions for different reasons.
1379 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1380 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1381 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1382 total_invocations() == HeapFirstMaximumCompactionCount;
1383 if (maximum_compaction || full_cp == top_cp || interval_ended) {
1384 _maximum_compaction_gc_num = total_invocations();
1385 return sd.region_to_addr(full_cp);
1386 }
1387
1388 const size_t space_live = pointer_delta(new_top, bottom);
1389 const size_t space_used = space->used_in_words();
1390 const size_t space_capacity = space->capacity_in_words();
1391
1392 const double density = double(space_live) / double(space_capacity);
1393 const size_t min_percent_free = MarkSweepDeadRatio;
1394 const double limiter = dead_wood_limiter(density, min_percent_free);
1395 const size_t dead_wood_max = space_used - space_live;
1396 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1397 dead_wood_max);
1398
1399 if (TraceParallelOldGCDensePrefix) {
1400 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1401 "space_cap=" SIZE_FORMAT,
1402 space_live, space_used,
1403 space_capacity);
1404 tty->print_cr("dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f "
1405 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1406 density, min_percent_free, limiter,
1407 dead_wood_max, dead_wood_limit);
1408 }
1409
1410 // Locate the region with the desired amount of dead space to the left.
1411 const RegionData* const limit_cp =
1412 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1413
1414 // Scan from the first region with dead space to the limit region and find the
1415 // one with the best (largest) reclaimed ratio.
1416 double best_ratio = 0.0;
1417 const RegionData* best_cp = full_cp;
1418 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1419 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1420 if (tmp_ratio > best_ratio) {
1421 best_cp = cp;
1422 best_ratio = tmp_ratio;
1423 }
1424 }
1425
1426 return sd.region_to_addr(best_cp);
1427 }
1428
1429 void PSParallelCompact::summarize_spaces_quick()
1430 {
1431 for (unsigned int i = 0; i < last_space_id; ++i) {
1432 const MutableSpace* space = _space_info[i].space();
1433 HeapWord** nta = _space_info[i].new_top_addr();
1434 bool result = _summary_data.summarize(_space_info[i].split_info(),
1435 space->bottom(), space->top(), NULL,
1436 space->bottom(), space->end(), nta);
1437 assert(result, "space must fit into itself");
1438 _space_info[i].set_dense_prefix(space->bottom());
1439 }
1440 }
1441
1442 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1443 {
1444 HeapWord* const dense_prefix_end = dense_prefix(id);
1445 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1446 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1447 if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1448 // Only enough dead space is filled so that any remaining dead space to the
1449 // left is larger than the minimum filler object. (The remainder is filled
1450 // during the copy/update phase.)
1451 //
1452 // The size of the dead space to the right of the boundary is not a
1453 // concern, since compaction will be able to use whatever space is
1454 // available.
1455 //
1456 // Here '||' is the boundary, 'x' represents a don't care bit and a box
1457 // surrounds the space to be filled with an object.
1458 //
1459 // In the 32-bit VM, each bit represents two 32-bit words:
1460 // +---+
1461 // a) beg_bits: ... x x x | 0 | || 0 x x ...
1462 // end_bits: ... x x x | 0 | || 0 x x ...
1463 // +---+
1464 //
1465 // In the 64-bit VM, each bit represents one 64-bit word:
1466 // +------------+
1467 // b) beg_bits: ... x x x | 0 || 0 | x x ...
1468 // end_bits: ... x x 1 | 0 || 0 | x x ...
1469 // +------------+
1470 // +-------+
1471 // c) beg_bits: ... x x | 0 0 | || 0 x x ...
1472 // end_bits: ... x 1 | 0 0 | || 0 x x ...
1473 // +-------+
1474 // +-----------+
1475 // d) beg_bits: ... x | 0 0 0 | || 0 x x ...
1476 // end_bits: ... 1 | 0 0 0 | || 0 x x ...
1477 // +-----------+
1478 // +-------+
1479 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ...
1480 // end_bits: ... 0 0 | 0 0 | || 0 x x ...
1481 // +-------+
1482
1483 // Initially assume case a, c or e will apply.
1484 size_t obj_len = CollectedHeap::min_fill_size();
1485 HeapWord* obj_beg = dense_prefix_end - obj_len;
1486
1487 #ifdef _LP64
1488 if (MinObjAlignment > 1) { // object alignment > heap word size
1489 // Cases a, c or e.
1490 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1491 // Case b above.
1492 obj_beg = dense_prefix_end - 1;
1493 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1494 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1495 // Case d above.
1496 obj_beg = dense_prefix_end - 3;
1497 obj_len = 3;
1498 }
1499 #endif // #ifdef _LP64
1500
1501 CollectedHeap::fill_with_object(obj_beg, obj_len);
1502 _mark_bitmap.mark_obj(obj_beg, obj_len);
1503 _summary_data.add_obj(obj_beg, obj_len);
1504 assert(start_array(id) != NULL, "sanity");
1505 start_array(id)->allocate_block(obj_beg);
1506 }
1507 }
1508
1509 void
1510 PSParallelCompact::clear_source_region(HeapWord* beg_addr, HeapWord* end_addr)
1511 {
1512 RegionData* const beg_ptr = _summary_data.addr_to_region_ptr(beg_addr);
1513 HeapWord* const end_aligned_up = _summary_data.region_align_up(end_addr);
1514 RegionData* const end_ptr = _summary_data.addr_to_region_ptr(end_aligned_up);
1515 for (RegionData* cur = beg_ptr; cur < end_ptr; ++cur) {
1516 cur->set_source_region(0);
1517 }
1518 }
1519
1520 void
1521 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1522 {
1523 assert(id < last_space_id, "id out of range");
1524 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(),
1525 "should have been reset in summarize_spaces_quick()");
1526
1527 const MutableSpace* space = _space_info[id].space();
1528 if (_space_info[id].new_top() != space->bottom()) {
1529 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1530 _space_info[id].set_dense_prefix(dense_prefix_end);
1531
1532 #ifndef PRODUCT
1533 if (TraceParallelOldGCDensePrefix) {
1534 print_dense_prefix_stats("ratio", id, maximum_compaction,
1535 dense_prefix_end);
1536 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1537 print_dense_prefix_stats("density", id, maximum_compaction, addr);
1538 }
1539 #endif // #ifndef PRODUCT
1540
1541 // Recompute the summary data, taking into account the dense prefix. If
1542 // every last byte will be reclaimed, then the existing summary data which
1543 // compacts everything can be left in place.
1544 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1545 // If dead space crosses the dense prefix boundary, it is (at least
1546 // partially) filled with a dummy object, marked live and added to the
1547 // summary data. This simplifies the copy/update phase and must be done
1548 // before the final locations of objects are determined, to prevent
1549 // leaving a fragment of dead space that is too small to fill.
1550 fill_dense_prefix_end(id);
1551
1552 // Compute the destination of each Region, and thus each object.
1553 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1554 _summary_data.summarize(_space_info[id].split_info(),
1555 dense_prefix_end, space->top(), NULL,
1556 dense_prefix_end, space->end(),
1557 _space_info[id].new_top_addr());
1558 }
1559 }
1560
1561 if (TraceParallelOldGCSummaryPhase) {
1562 const size_t region_size = ParallelCompactData::RegionSize;
1563 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1564 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1565 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1566 HeapWord* const new_top = _space_info[id].new_top();
1567 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1568 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1569 tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1570 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1571 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1572 id, space->capacity_in_words(), p2i(dense_prefix_end),
1573 dp_region, dp_words / region_size,
1574 cr_words / region_size, p2i(new_top));
1575 }
1576 }
1577
1578 #ifndef PRODUCT
1579 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1580 HeapWord* dst_beg, HeapWord* dst_end,
1581 SpaceId src_space_id,
1582 HeapWord* src_beg, HeapWord* src_end)
1583 {
1584 if (TraceParallelOldGCSummaryPhase) {
1585 tty->print_cr("summarizing %d [%s] into %d [%s]: "
1586 "src=" PTR_FORMAT "-" PTR_FORMAT " "
1587 SIZE_FORMAT "-" SIZE_FORMAT " "
1588 "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1589 SIZE_FORMAT "-" SIZE_FORMAT,
1590 src_space_id, space_names[src_space_id],
1591 dst_space_id, space_names[dst_space_id],
1592 p2i(src_beg), p2i(src_end),
1593 _summary_data.addr_to_region_idx(src_beg),
1594 _summary_data.addr_to_region_idx(src_end),
1595 p2i(dst_beg), p2i(dst_end),
1596 _summary_data.addr_to_region_idx(dst_beg),
1597 _summary_data.addr_to_region_idx(dst_end));
1598 }
1599 }
1600 #endif // #ifndef PRODUCT
1601
1602 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1603 bool maximum_compaction)
1604 {
1605 GCTraceTime tm("summary phase", print_phases(), true, &_gc_timer);
1606 // trace("2");
1607
1608 #ifdef ASSERT
1609 if (TraceParallelOldGCMarkingPhase) {
1610 tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1611 "add_obj_bytes=" SIZE_FORMAT,
1612 add_obj_count, add_obj_size * HeapWordSize);
1613 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1614 "mark_bitmap_bytes=" SIZE_FORMAT,
1615 mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1616 }
1617 #endif // #ifdef ASSERT
1618
1619 // Quick summarization of each space into itself, to see how much is live.
1620 summarize_spaces_quick();
1621
1622 if (TraceParallelOldGCSummaryPhase) {
1623 tty->print_cr("summary_phase: after summarizing each space to self");
1624 Universe::print();
1625 NOT_PRODUCT(print_region_ranges());
1626 if (Verbose) {
1627 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1628 }
1629 }
1630
1631 // The amount of live data that will end up in old space (assuming it fits).
1632 size_t old_space_total_live = 0;
1633 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1634 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1635 _space_info[id].space()->bottom());
1636 }
1637
1638 MutableSpace* const old_space = _space_info[old_space_id].space();
1639 const size_t old_capacity = old_space->capacity_in_words();
1640 if (old_space_total_live > old_capacity) {
1641 // XXX - should also try to expand
1642 maximum_compaction = true;
1643 }
1644
1645 // Old generations.
1646 summarize_space(old_space_id, maximum_compaction);
1647
1648 // Summarize the remaining spaces in the young gen. The initial target space
1649 // is the old gen. If a space does not fit entirely into the target, then the
1650 // remainder is compacted into the space itself and that space becomes the new
1651 // target.
1652 SpaceId dst_space_id = old_space_id;
1653 HeapWord* dst_space_end = old_space->end();
1654 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1655 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1656 const MutableSpace* space = _space_info[id].space();
1657 const size_t live = pointer_delta(_space_info[id].new_top(),
1658 space->bottom());
1659 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1660
1661 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1662 SpaceId(id), space->bottom(), space->top());)
1663 if (live > 0 && live <= available) {
1664 // All the live data will fit.
1665 bool done = _summary_data.summarize(_space_info[id].split_info(),
1666 space->bottom(), space->top(),
1667 NULL,
1668 *new_top_addr, dst_space_end,
1669 new_top_addr);
1670 assert(done, "space must fit into old gen");
1671
1672 // Reset the new_top value for the space.
1673 _space_info[id].set_new_top(space->bottom());
1674 } else if (live > 0) {
1675 // Attempt to fit part of the source space into the target space.
1676 HeapWord* next_src_addr = NULL;
1677 bool done = _summary_data.summarize(_space_info[id].split_info(),
1678 space->bottom(), space->top(),
1679 &next_src_addr,
1680 *new_top_addr, dst_space_end,
1681 new_top_addr);
1682 assert(!done, "space should not fit into old gen");
1683 assert(next_src_addr != NULL, "sanity");
1684
1685 // The source space becomes the new target, so the remainder is compacted
1686 // within the space itself.
1687 dst_space_id = SpaceId(id);
1688 dst_space_end = space->end();
1689 new_top_addr = _space_info[id].new_top_addr();
1690 NOT_PRODUCT(summary_phase_msg(dst_space_id,
1691 space->bottom(), dst_space_end,
1692 SpaceId(id), next_src_addr, space->top());)
1693 done = _summary_data.summarize(_space_info[id].split_info(),
1694 next_src_addr, space->top(),
1695 NULL,
1696 space->bottom(), dst_space_end,
1697 new_top_addr);
1698 assert(done, "space must fit when compacted into itself");
1699 assert(*new_top_addr <= space->top(), "usage should not grow");
1700 }
1701 }
1702
1703 if (TraceParallelOldGCSummaryPhase) {
1704 tty->print_cr("summary_phase: after final summarization");
1705 Universe::print();
1706 NOT_PRODUCT(print_region_ranges());
1707 if (Verbose) {
1708 NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info));
1709 }
1710 }
1711 }
1712
1713 // This method should contain all heap-specific policy for invoking a full
1714 // collection. invoke_no_policy() will only attempt to compact the heap; it
1715 // will do nothing further. If we need to bail out for policy reasons, scavenge
1716 // before full gc, or any other specialized behavior, it needs to be added here.
1717 //
1718 // Note that this method should only be called from the vm_thread while at a
1719 // safepoint.
1720 //
1721 // Note that the all_soft_refs_clear flag in the collector policy
1722 // may be true because this method can be called without intervening
1723 // activity. For example when the heap space is tight and full measure
1724 // are being taken to free space.
1725 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1726 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1727 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1728 "should be in vm thread");
1729
1730 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1731 GCCause::Cause gc_cause = heap->gc_cause();
1732 assert(!heap->is_gc_active(), "not reentrant");
1733
1734 PSAdaptiveSizePolicy* policy = heap->size_policy();
1735 IsGCActiveMark mark;
1736
1737 if (ScavengeBeforeFullGC) {
1738 PSScavenge::invoke_no_policy();
1739 }
1740
1741 const bool clear_all_soft_refs =
1742 heap->collector_policy()->should_clear_all_soft_refs();
1743
1744 PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1745 maximum_heap_compaction);
1746 }
1747
1748 // This method contains no policy. You should probably
1749 // be calling invoke() instead.
1750 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1751 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1752 assert(ref_processor() != NULL, "Sanity");
1753
1754 if (GC_locker::check_active_before_gc()) {
1755 return false;
1756 }
1757
1758 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1759
1760 GCIdMark gc_id_mark;
1761 _gc_timer.register_gc_start();
1762 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
1763
1764 TimeStamp marking_start;
1765 TimeStamp compaction_start;
1766 TimeStamp collection_exit;
1767
1768 GCCause::Cause gc_cause = heap->gc_cause();
1769 PSYoungGen* young_gen = heap->young_gen();
1770 PSOldGen* old_gen = heap->old_gen();
1771 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1772
1773 // The scope of casr should end after code that can change
1774 // CollectorPolicy::_should_clear_all_soft_refs.
1775 ClearedAllSoftRefs casr(maximum_heap_compaction,
1776 heap->collector_policy());
1777
1778 if (ZapUnusedHeapArea) {
1779 // Save information needed to minimize mangling
1780 heap->record_gen_tops_before_GC();
1781 }
1782
1783 heap->pre_full_gc_dump(&_gc_timer);
1784
1785 _print_phases = PrintGCDetails && PrintParallelOldGCPhaseTimes;
1786
1787 // Make sure data structures are sane, make the heap parsable, and do other
1788 // miscellaneous bookkeeping.
1789 PreGCValues pre_gc_values;
1790 pre_compact(&pre_gc_values);
1791
1792 // Get the compaction manager reserved for the VM thread.
1793 ParCompactionManager* const vmthread_cm =
1794 ParCompactionManager::manager_array(gc_task_manager()->workers());
1795
1796 // Place after pre_compact() where the number of invocations is incremented.
1797 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
1798
1799 {
1800 ResourceMark rm;
1801 HandleMark hm;
1802
1803 // Set the number of GC threads to be used in this collection
1804 gc_task_manager()->set_active_gang();
1805 gc_task_manager()->task_idle_workers();
1806
1807 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
1808 GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL);
1809 TraceCollectorStats tcs(counters());
1810 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
1811
1812 if (TraceOldGenTime) accumulated_time()->start();
1813
1814 // Let the size policy know we're starting
1815 size_policy->major_collection_begin();
1816
1817 CodeCache::gc_prologue();
1818
1819 #if defined(COMPILER2) || INCLUDE_JVMCI
1820 DerivedPointerTable::clear();
1821 #endif
1822
1823 ref_processor()->enable_discovery();
1824 ref_processor()->setup_policy(maximum_heap_compaction);
1825
1826 bool marked_for_unloading = false;
1827
1828 marking_start.update();
1829 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer);
1830
1831 bool max_on_system_gc = UseMaximumCompactionOnSystemGC
1832 && GCCause::is_user_requested_gc(gc_cause);
1833 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
1834
1835 #if defined(COMPILER2) || INCLUDE_JVMCI
1836 assert(DerivedPointerTable::is_active(), "Sanity");
1837 DerivedPointerTable::set_active(false);
1838 #endif
1839
1840 // adjust_roots() updates Universe::_intArrayKlassObj which is
1841 // needed by the compaction for filling holes in the dense prefix.
1842 adjust_roots();
1843
1844 compaction_start.update();
1845 compact();
1846
1847 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
1848 // done before resizing.
1849 post_compact();
1850
1851 // Let the size policy know we're done
1852 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
1853
1854 if (UseAdaptiveSizePolicy) {
1855 if (PrintAdaptiveSizePolicy) {
1856 gclog_or_tty->print("AdaptiveSizeStart: ");
1857 gclog_or_tty->stamp();
1858 gclog_or_tty->print_cr(" collection: %d ",
1859 heap->total_collections());
1860 if (Verbose) {
1861 gclog_or_tty->print("old_gen_capacity: " SIZE_FORMAT
1862 " young_gen_capacity: " SIZE_FORMAT,
1863 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
1864 }
1865 }
1866
1867 // Don't check if the size_policy is ready here. Let
1868 // the size_policy check that internally.
1869 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
1870 AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
1871 // Swap the survivor spaces if from_space is empty. The
1872 // resize_young_gen() called below is normally used after
1873 // a successful young GC and swapping of survivor spaces;
1874 // otherwise, it will fail to resize the young gen with
1875 // the current implementation.
1876 if (young_gen->from_space()->is_empty()) {
1877 young_gen->from_space()->clear(SpaceDecorator::Mangle);
1878 young_gen->swap_spaces();
1879 }
1880
1881 // Calculate optimal free space amounts
1882 assert(young_gen->max_size() >
1883 young_gen->from_space()->capacity_in_bytes() +
1884 young_gen->to_space()->capacity_in_bytes(),
1885 "Sizes of space in young gen are out-of-bounds");
1886
1887 size_t young_live = young_gen->used_in_bytes();
1888 size_t eden_live = young_gen->eden_space()->used_in_bytes();
1889 size_t old_live = old_gen->used_in_bytes();
1890 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
1891 size_t max_old_gen_size = old_gen->max_gen_size();
1892 size_t max_eden_size = young_gen->max_size() -
1893 young_gen->from_space()->capacity_in_bytes() -
1894 young_gen->to_space()->capacity_in_bytes();
1895
1896 // Used for diagnostics
1897 size_policy->clear_generation_free_space_flags();
1898
1899 size_policy->compute_generations_free_space(young_live,
1900 eden_live,
1901 old_live,
1902 cur_eden,
1903 max_old_gen_size,
1904 max_eden_size,
1905 true /* full gc*/);
1906
1907 size_policy->check_gc_overhead_limit(young_live,
1908 eden_live,
1909 max_old_gen_size,
1910 max_eden_size,
1911 true /* full gc*/,
1912 gc_cause,
1913 heap->collector_policy());
1914
1915 size_policy->decay_supplemental_growth(true /* full gc*/);
1916
1917 heap->resize_old_gen(
1918 size_policy->calculated_old_free_size_in_bytes());
1919
1920 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
1921 size_policy->calculated_survivor_size_in_bytes());
1922 }
1923 if (PrintAdaptiveSizePolicy) {
1924 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
1925 heap->total_collections());
1926 }
1927 }
1928
1929 if (UsePerfData) {
1930 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
1931 counters->update_counters();
1932 counters->update_old_capacity(old_gen->capacity_in_bytes());
1933 counters->update_young_capacity(young_gen->capacity_in_bytes());
1934 }
1935
1936 heap->resize_all_tlabs();
1937
1938 // Resize the metaspace capacity after a collection
1939 MetaspaceGC::compute_new_size();
1940
1941 if (TraceOldGenTime) accumulated_time()->stop();
1942
1943 if (PrintGC) {
1944 if (PrintGCDetails) {
1945 // No GC timestamp here. This is after GC so it would be confusing.
1946 young_gen->print_used_change(pre_gc_values.young_gen_used());
1947 old_gen->print_used_change(pre_gc_values.old_gen_used());
1948 heap->print_heap_change(pre_gc_values.heap_used());
1949 MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used());
1950 } else {
1951 heap->print_heap_change(pre_gc_values.heap_used());
1952 }
1953 }
1954
1955 // Track memory usage and detect low memory
1956 MemoryService::track_memory_usage();
1957 heap->update_counters();
1958 gc_task_manager()->release_idle_workers();
1959 }
1960
1961 #ifdef ASSERT
1962 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
1963 ParCompactionManager* const cm =
1964 ParCompactionManager::manager_array(int(i));
1965 assert(cm->marking_stack()->is_empty(), "should be empty");
1966 assert(ParCompactionManager::region_list(int(i))->is_empty(), "should be empty");
1967 }
1968 #endif // ASSERT
1969
1970 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1971 HandleMark hm; // Discard invalid handles created during verification
1972 Universe::verify(" VerifyAfterGC:");
1973 }
1974
1975 // Re-verify object start arrays
1976 if (VerifyObjectStartArray &&
1977 VerifyAfterGC) {
1978 old_gen->verify_object_start_array();
1979 }
1980
1981 if (ZapUnusedHeapArea) {
1982 old_gen->object_space()->check_mangled_unused_area_complete();
1983 }
1984
1985 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1986
1987 collection_exit.update();
1988
1989 heap->print_heap_after_gc();
1990 heap->trace_heap_after_gc(&_gc_tracer);
1991
1992 if (PrintGCTaskTimeStamps) {
1993 gclog_or_tty->print_cr("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " "
1994 JLONG_FORMAT,
1995 marking_start.ticks(), compaction_start.ticks(),
1996 collection_exit.ticks());
1997 gc_task_manager()->print_task_time_stamps();
1998 }
1999
2000 heap->post_full_gc_dump(&_gc_timer);
2001
2002 #ifdef TRACESPINNING
2003 ParallelTaskTerminator::print_termination_counts();
2004 #endif
2005
2006 _gc_timer.register_gc_end();
2007
2008 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
2009 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
2010
2011 return true;
2012 }
2013
2014 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
2015 PSYoungGen* young_gen,
2016 PSOldGen* old_gen) {
2017 MutableSpace* const eden_space = young_gen->eden_space();
2018 assert(!eden_space->is_empty(), "eden must be non-empty");
2019 assert(young_gen->virtual_space()->alignment() ==
2020 old_gen->virtual_space()->alignment(), "alignments do not match");
2021
2022 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
2023 return false;
2024 }
2025
2026 // Both generations must be completely committed.
2027 if (young_gen->virtual_space()->uncommitted_size() != 0) {
2028 return false;
2029 }
2030 if (old_gen->virtual_space()->uncommitted_size() != 0) {
2031 return false;
2032 }
2033
2034 // Figure out how much to take from eden. Include the average amount promoted
2035 // in the total; otherwise the next young gen GC will simply bail out to a
2036 // full GC.
2037 const size_t alignment = old_gen->virtual_space()->alignment();
2038 const size_t eden_used = eden_space->used_in_bytes();
2039 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
2040 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
2041 const size_t eden_capacity = eden_space->capacity_in_bytes();
2042
2043 if (absorb_size >= eden_capacity) {
2044 return false; // Must leave some space in eden.
2045 }
2046
2047 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2048 if (new_young_size < young_gen->min_gen_size()) {
2049 return false; // Respect young gen minimum size.
2050 }
2051
2052 if (TraceAdaptiveGCBoundary && Verbose) {
2053 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
2054 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2055 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2056 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2057 absorb_size / K,
2058 eden_capacity / K, (eden_capacity - absorb_size) / K,
2059 young_gen->from_space()->used_in_bytes() / K,
2060 young_gen->to_space()->used_in_bytes() / K,
2061 young_gen->capacity_in_bytes() / K, new_young_size / K);
2062 }
2063
2064 // Fill the unused part of the old gen.
2065 MutableSpace* const old_space = old_gen->object_space();
2066 HeapWord* const unused_start = old_space->top();
2067 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2068
2069 if (unused_words > 0) {
2070 if (unused_words < CollectedHeap::min_fill_size()) {
2071 return false; // If the old gen cannot be filled, must give up.
2072 }
2073 CollectedHeap::fill_with_objects(unused_start, unused_words);
2074 }
2075
2076 // Take the live data from eden and set both top and end in the old gen to
2077 // eden top. (Need to set end because reset_after_change() mangles the region
2078 // from end to virtual_space->high() in debug builds).
2079 HeapWord* const new_top = eden_space->top();
2080 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2081 absorb_size);
2082 young_gen->reset_after_change();
2083 old_space->set_top(new_top);
2084 old_space->set_end(new_top);
2085 old_gen->reset_after_change();
2086
2087 // Update the object start array for the filler object and the data from eden.
2088 ObjectStartArray* const start_array = old_gen->start_array();
2089 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2090 start_array->allocate_block(p);
2091 }
2092
2093 // Could update the promoted average here, but it is not typically updated at
2094 // full GCs and the value to use is unclear. Something like
2095 //
2096 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2097
2098 size_policy->set_bytes_absorbed_from_eden(absorb_size);
2099 return true;
2100 }
2101
2102 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2103 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2104 "shouldn't return NULL");
2105 return ParallelScavengeHeap::gc_task_manager();
2106 }
2107
2108 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2109 bool maximum_heap_compaction,
2110 ParallelOldTracer *gc_tracer) {
2111 // Recursively traverse all live objects and mark them
2112 GCTraceTime tm("marking phase", print_phases(), true, &_gc_timer);
2113
2114 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2115 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2116 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2117 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2118 ParallelTaskTerminator terminator(active_gc_threads, qset);
2119
2120 ParCompactionManager::MarkAndPushClosure mark_and_push_closure(cm);
2121 ParCompactionManager::FollowStackClosure follow_stack_closure(cm);
2122
2123 // Need new claim bits before marking starts.
2124 ClassLoaderDataGraph::clear_claimed_marks();
2125
2126 {
2127 GCTraceTime tm_m("par mark", print_phases(), true, &_gc_timer);
2128
2129 ParallelScavengeHeap::ParStrongRootsScope psrs;
2130
2131 GCTaskQueue* q = GCTaskQueue::create();
2132
2133 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2134 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2135 // We scan the thread roots in parallel
2136 Threads::create_thread_roots_marking_tasks(q);
2137 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2138 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
2139 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2140 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2141 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data));
2142 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2143 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2144
2145 if (active_gc_threads > 1) {
2146 for (uint j = 0; j < active_gc_threads; j++) {
2147 q->enqueue(new StealMarkingTask(&terminator));
2148 }
2149 }
2150
2151 gc_task_manager()->execute_and_wait(q);
2152 }
2153
2154 // Process reference objects found during marking
2155 {
2156 GCTraceTime tm_r("reference processing", print_phases(), true, &_gc_timer);
2157
2158 ReferenceProcessorStats stats;
2159 if (ref_processor()->processing_is_mt()) {
2160 RefProcTaskExecutor task_executor;
2161 stats = ref_processor()->process_discovered_references(
2162 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2163 &task_executor, &_gc_timer);
2164 } else {
2165 stats = ref_processor()->process_discovered_references(
2166 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
2167 &_gc_timer);
2168 }
2169
2170 gc_tracer->report_gc_reference_stats(stats);
2171 }
2172
2173 GCTraceTime tm_c("class unloading", print_phases(), true, &_gc_timer);
2174
2175 // This is the point where the entire marking should have completed.
2176 assert(cm->marking_stacks_empty(), "Marking should have completed");
2177
2178 // Follow system dictionary roots and unload classes.
2179 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
2180
2181 // Unload nmethods.
2182 CodeCache::do_unloading(is_alive_closure(), purged_class);
2183
2184 // Prune dead klasses from subklass/sibling/implementor lists.
2185 Klass::clean_weak_klass_links(is_alive_closure());
2186
2187 // Delete entries for dead interned strings.
2188 StringTable::unlink(is_alive_closure());
2189
2190 // Clean up unreferenced symbols in symbol table.
2191 SymbolTable::unlink();
2192 _gc_tracer.report_object_count_after_gc(is_alive_closure());
2193 }
2194
2195 // This should be moved to the shared markSweep code!
2196 class PSAlwaysTrueClosure: public BoolObjectClosure {
2197 public:
2198 bool do_object_b(oop p) { return true; }
2199 };
2200 static PSAlwaysTrueClosure always_true;
2201
2202 void PSParallelCompact::adjust_roots() {
2203 // Adjust the pointers to reflect the new locations
2204 GCTraceTime tm("adjust roots", print_phases(), true, &_gc_timer);
2205
2206 // Need new claim bits when tracing through and adjusting pointers.
2207 ClassLoaderDataGraph::clear_claimed_marks();
2208
2209 // General strong roots.
2210 Universe::oops_do(adjust_pointer_closure());
2211 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
2212 CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
2213 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
2214 ObjectSynchronizer::oops_do(adjust_pointer_closure());
2215 FlatProfiler::oops_do(adjust_pointer_closure());
2216 Management::oops_do(adjust_pointer_closure());
2217 JvmtiExport::oops_do(adjust_pointer_closure());
2218 SystemDictionary::oops_do(adjust_pointer_closure());
2219 ClassLoaderDataGraph::oops_do(adjust_pointer_closure(), adjust_klass_closure(), true);
2220
2221 // Now adjust pointers in remaining weak roots. (All of which should
2222 // have been cleared if they pointed to non-surviving objects.)
2223 // Global (weak) JNI handles
2224 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure());
2225
2226 CodeBlobToOopClosure adjust_from_blobs(adjust_pointer_closure(), CodeBlobToOopClosure::FixRelocations);
2227 CodeCache::blobs_do(&adjust_from_blobs);
2228 StringTable::oops_do(adjust_pointer_closure());
2229 ref_processor()->weak_oops_do(adjust_pointer_closure());
2230 // Roots were visited so references into the young gen in roots
2231 // may have been scanned. Process them also.
2232 // Should the reference processor have a span that excludes
2233 // young gen objects?
2234 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
2235 }
2236
2237 void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q,
2238 uint parallel_gc_threads)
2239 {
2240 GCTraceTime tm("drain task setup", print_phases(), true, &_gc_timer);
2241
2242 // Find the threads that are active
2243 unsigned int which = 0;
2244
2245 const uint task_count = MAX2(parallel_gc_threads, 1U);
2246 for (uint j = 0; j < task_count; j++) {
2247 q->enqueue(new DrainStacksCompactionTask(j));
2248 ParCompactionManager::verify_region_list_empty(j);
2249 // Set the region stacks variables to "no" region stack values
2250 // so that they will be recognized and needing a region stack
2251 // in the stealing tasks if they do not get one by executing
2252 // a draining stack.
2253 ParCompactionManager* cm = ParCompactionManager::manager_array(j);
2254 cm->set_region_stack(NULL);
2255 cm->set_region_stack_index((uint)max_uintx);
2256 }
2257 ParCompactionManager::reset_recycled_stack_index();
2258
2259 // Find all regions that are available (can be filled immediately) and
2260 // distribute them to the thread stacks. The iteration is done in reverse
2261 // order (high to low) so the regions will be removed in ascending order.
2262
2263 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2264
2265 size_t fillable_regions = 0; // A count for diagnostic purposes.
2266 // A region index which corresponds to the tasks created above.
2267 // "which" must be 0 <= which < task_count
2268
2269 which = 0;
2270 // id + 1 is used to test termination so unsigned can
2271 // be used with an old_space_id == 0.
2272 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2273 SpaceInfo* const space_info = _space_info + id;
2274 MutableSpace* const space = space_info->space();
2275 HeapWord* const new_top = space_info->new_top();
2276
2277 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2278 const size_t end_region =
2279 sd.addr_to_region_idx(sd.region_align_up(new_top));
2280
2281 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2282 if (sd.region(cur)->claim_unsafe()) {
2283 ParCompactionManager::region_list_push(which, cur);
2284
2285 if (TraceParallelOldGCCompactionPhase && Verbose) {
2286 const size_t count_mod_8 = fillable_regions & 7;
2287 if (count_mod_8 == 0) gclog_or_tty->print("fillable: ");
2288 gclog_or_tty->print(" " SIZE_FORMAT_W(7), cur);
2289 if (count_mod_8 == 7) gclog_or_tty->cr();
2290 }
2291
2292 NOT_PRODUCT(++fillable_regions;)
2293
2294 // Assign regions to tasks in round-robin fashion.
2295 if (++which == task_count) {
2296 assert(which <= parallel_gc_threads,
2297 "Inconsistent number of workers");
2298 which = 0;
2299 }
2300 }
2301 }
2302 }
2303
2304 if (TraceParallelOldGCCompactionPhase) {
2305 if (Verbose && (fillable_regions & 7) != 0) gclog_or_tty->cr();
2306 gclog_or_tty->print_cr(SIZE_FORMAT " initially fillable regions", fillable_regions);
2307 }
2308 }
2309
2310 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2311
2312 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2313 uint parallel_gc_threads) {
2314 GCTraceTime tm("dense prefix task setup", print_phases(), true, &_gc_timer);
2315
2316 ParallelCompactData& sd = PSParallelCompact::summary_data();
2317
2318 // Iterate over all the spaces adding tasks for updating
2319 // regions in the dense prefix. Assume that 1 gc thread
2320 // will work on opening the gaps and the remaining gc threads
2321 // will work on the dense prefix.
2322 unsigned int space_id;
2323 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2324 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2325 const MutableSpace* const space = _space_info[space_id].space();
2326
2327 if (dense_prefix_end == space->bottom()) {
2328 // There is no dense prefix for this space.
2329 continue;
2330 }
2331
2332 // The dense prefix is before this region.
2333 size_t region_index_end_dense_prefix =
2334 sd.addr_to_region_idx(dense_prefix_end);
2335 RegionData* const dense_prefix_cp =
2336 sd.region(region_index_end_dense_prefix);
2337 assert(dense_prefix_end == space->end() ||
2338 dense_prefix_cp->available() ||
2339 dense_prefix_cp->claimed(),
2340 "The region after the dense prefix should always be ready to fill");
2341
2342 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2343
2344 // Is there dense prefix work?
2345 size_t total_dense_prefix_regions =
2346 region_index_end_dense_prefix - region_index_start;
2347 // How many regions of the dense prefix should be given to
2348 // each thread?
2349 if (total_dense_prefix_regions > 0) {
2350 uint tasks_for_dense_prefix = 1;
2351 if (total_dense_prefix_regions <=
2352 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2353 // Don't over partition. This assumes that
2354 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2355 // so there are not many regions to process.
2356 tasks_for_dense_prefix = parallel_gc_threads;
2357 } else {
2358 // Over partition
2359 tasks_for_dense_prefix = parallel_gc_threads *
2360 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2361 }
2362 size_t regions_per_thread = total_dense_prefix_regions /
2363 tasks_for_dense_prefix;
2364 // Give each thread at least 1 region.
2365 if (regions_per_thread == 0) {
2366 regions_per_thread = 1;
2367 }
2368
2369 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2370 if (region_index_start >= region_index_end_dense_prefix) {
2371 break;
2372 }
2373 // region_index_end is not processed
2374 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2375 region_index_end_dense_prefix);
2376 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2377 region_index_start,
2378 region_index_end));
2379 region_index_start = region_index_end;
2380 }
2381 }
2382 // This gets any part of the dense prefix that did not
2383 // fit evenly.
2384 if (region_index_start < region_index_end_dense_prefix) {
2385 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2386 region_index_start,
2387 region_index_end_dense_prefix));
2388 }
2389 }
2390 }
2391
2392 void PSParallelCompact::enqueue_region_stealing_tasks(
2393 GCTaskQueue* q,
2394 ParallelTaskTerminator* terminator_ptr,
2395 uint parallel_gc_threads) {
2396 GCTraceTime tm("steal task setup", print_phases(), true, &_gc_timer);
2397
2398 // Once a thread has drained it's stack, it should try to steal regions from
2399 // other threads.
2400 if (parallel_gc_threads > 1) {
2401 for (uint j = 0; j < parallel_gc_threads; j++) {
2402 q->enqueue(new StealRegionCompactionTask(terminator_ptr));
2403 }
2404 }
2405 }
2406
2407 #ifdef ASSERT
2408 // Write a histogram of the number of times the block table was filled for a
2409 // region.
2410 void PSParallelCompact::write_block_fill_histogram(outputStream* const out)
2411 {
2412 if (!TraceParallelOldGCCompactionPhase) return;
2413
2414 typedef ParallelCompactData::RegionData rd_t;
2415 ParallelCompactData& sd = summary_data();
2416
2417 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2418 MutableSpace* const spc = _space_info[id].space();
2419 if (spc->bottom() != spc->top()) {
2420 const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
2421 HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
2422 const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
2423
2424 size_t histo[5] = { 0, 0, 0, 0, 0 };
2425 const size_t histo_len = sizeof(histo) / sizeof(size_t);
2426 const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
2427
2428 for (const rd_t* cur = beg; cur < end; ++cur) {
2429 ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
2430 }
2431 out->print("%u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
2432 for (size_t i = 0; i < histo_len; ++i) {
2433 out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
2434 histo[i], 100.0 * histo[i] / region_cnt);
2435 }
2436 out->cr();
2437 }
2438 }
2439 }
2440 #endif // #ifdef ASSERT
2441
2442 void PSParallelCompact::compact() {
2443 // trace("5");
2444 GCTraceTime tm("compaction phase", print_phases(), true, &_gc_timer);
2445
2446 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2447 PSOldGen* old_gen = heap->old_gen();
2448 old_gen->start_array()->reset();
2449 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2450 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2451 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2452 ParallelTaskTerminator terminator(active_gc_threads, qset);
2453
2454 GCTaskQueue* q = GCTaskQueue::create();
2455 enqueue_region_draining_tasks(q, active_gc_threads);
2456 enqueue_dense_prefix_tasks(q, active_gc_threads);
2457 enqueue_region_stealing_tasks(q, &terminator, active_gc_threads);
2458
2459 {
2460 GCTraceTime tm_pc("par compact", print_phases(), true, &_gc_timer);
2461
2462 gc_task_manager()->execute_and_wait(q);
2463
2464 #ifdef ASSERT
2465 // Verify that all regions have been processed before the deferred updates.
2466 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2467 verify_complete(SpaceId(id));
2468 }
2469 #endif
2470 }
2471
2472 {
2473 // Update the deferred objects, if any. Any compaction manager can be used.
2474 GCTraceTime tm_du("deferred updates", print_phases(), true, &_gc_timer);
2475 ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2476 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2477 update_deferred_objects(cm, SpaceId(id));
2478 }
2479 }
2480
2481 DEBUG_ONLY(write_block_fill_histogram(gclog_or_tty));
2482 }
2483
2484 #ifdef ASSERT
2485 void PSParallelCompact::verify_complete(SpaceId space_id) {
2486 // All Regions between space bottom() to new_top() should be marked as filled
2487 // and all Regions between new_top() and top() should be available (i.e.,
2488 // should have been emptied).
2489 ParallelCompactData& sd = summary_data();
2490 SpaceInfo si = _space_info[space_id];
2491 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2492 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2493 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2494 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2495 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2496
2497 bool issued_a_warning = false;
2498
2499 size_t cur_region;
2500 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2501 const RegionData* const c = sd.region(cur_region);
2502 if (!c->completed()) {
2503 warning("region " SIZE_FORMAT " not filled: "
2504 "destination_count=%u",
2505 cur_region, c->destination_count());
2506 issued_a_warning = true;
2507 }
2508 }
2509
2510 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2511 const RegionData* const c = sd.region(cur_region);
2512 if (!c->available()) {
2513 warning("region " SIZE_FORMAT " not empty: "
2514 "destination_count=%u",
2515 cur_region, c->destination_count());
2516 issued_a_warning = true;
2517 }
2518 }
2519
2520 if (issued_a_warning) {
2521 print_region_ranges();
2522 }
2523 }
2524 #endif // #ifdef ASSERT
2525
2526 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) {
2527 _start_array->allocate_block(addr);
2528 compaction_manager()->update_contents(oop(addr));
2529 }
2530
2531 // Update interior oops in the ranges of regions [beg_region, end_region).
2532 void
2533 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2534 SpaceId space_id,
2535 size_t beg_region,
2536 size_t end_region) {
2537 ParallelCompactData& sd = summary_data();
2538 ParMarkBitMap* const mbm = mark_bitmap();
2539
2540 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2541 HeapWord* const end_addr = sd.region_to_addr(end_region);
2542 assert(beg_region <= end_region, "bad region range");
2543 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2544
2545 #ifdef ASSERT
2546 // Claim the regions to avoid triggering an assert when they are marked as
2547 // filled.
2548 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2549 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2550 }
2551 #endif // #ifdef ASSERT
2552
2553 if (beg_addr != space(space_id)->bottom()) {
2554 // Find the first live object or block of dead space that *starts* in this
2555 // range of regions. If a partial object crosses onto the region, skip it;
2556 // it will be marked for 'deferred update' when the object head is
2557 // processed. If dead space crosses onto the region, it is also skipped; it
2558 // will be filled when the prior region is processed. If neither of those
2559 // apply, the first word in the region is the start of a live object or dead
2560 // space.
2561 assert(beg_addr > space(space_id)->bottom(), "sanity");
2562 const RegionData* const cp = sd.region(beg_region);
2563 if (cp->partial_obj_size() != 0) {
2564 beg_addr = sd.partial_obj_end(beg_region);
2565 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2566 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2567 }
2568 }
2569
2570 if (beg_addr < end_addr) {
2571 // A live object or block of dead space starts in this range of Regions.
2572 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2573
2574 // Create closures and iterate.
2575 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2576 FillClosure fill_closure(cm, space_id);
2577 ParMarkBitMap::IterationStatus status;
2578 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2579 dense_prefix_end);
2580 if (status == ParMarkBitMap::incomplete) {
2581 update_closure.do_addr(update_closure.source());
2582 }
2583 }
2584
2585 // Mark the regions as filled.
2586 RegionData* const beg_cp = sd.region(beg_region);
2587 RegionData* const end_cp = sd.region(end_region);
2588 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2589 cp->set_completed();
2590 }
2591 }
2592
2593 // Return the SpaceId for the space containing addr. If addr is not in the
2594 // heap, last_space_id is returned. In debug mode it expects the address to be
2595 // in the heap and asserts such.
2596 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2597 assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
2598
2599 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2600 if (_space_info[id].space()->contains(addr)) {
2601 return SpaceId(id);
2602 }
2603 }
2604
2605 assert(false, "no space contains the addr");
2606 return last_space_id;
2607 }
2608
2609 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2610 SpaceId id) {
2611 assert(id < last_space_id, "bad space id");
2612
2613 ParallelCompactData& sd = summary_data();
2614 const SpaceInfo* const space_info = _space_info + id;
2615 ObjectStartArray* const start_array = space_info->start_array();
2616
2617 const MutableSpace* const space = space_info->space();
2618 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2619 HeapWord* const beg_addr = space_info->dense_prefix();
2620 HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2621
2622 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2623 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2624 const RegionData* cur_region;
2625 for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2626 HeapWord* const addr = cur_region->deferred_obj_addr();
2627 if (addr != NULL) {
2628 if (start_array != NULL) {
2629 start_array->allocate_block(addr);
2630 }
2631 cm->update_contents(oop(addr));
2632 assert(oop(addr)->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(addr)));
2633 }
2634 }
2635 }
2636
2637 // Skip over count live words starting from beg, and return the address of the
2638 // next live word. Unless marked, the word corresponding to beg is assumed to
2639 // be dead. Callers must either ensure beg does not correspond to the middle of
2640 // an object, or account for those live words in some other way. Callers must
2641 // also ensure that there are enough live words in the range [beg, end) to skip.
2642 HeapWord*
2643 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2644 {
2645 assert(count > 0, "sanity");
2646
2647 ParMarkBitMap* m = mark_bitmap();
2648 idx_t bits_to_skip = m->words_to_bits(count);
2649 idx_t cur_beg = m->addr_to_bit(beg);
2650 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
2651
2652 do {
2653 cur_beg = m->find_obj_beg(cur_beg, search_end);
2654 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2655 const size_t obj_bits = cur_end - cur_beg + 1;
2656 if (obj_bits > bits_to_skip) {
2657 return m->bit_to_addr(cur_beg + bits_to_skip);
2658 }
2659 bits_to_skip -= obj_bits;
2660 cur_beg = cur_end + 1;
2661 } while (bits_to_skip > 0);
2662
2663 // Skipping the desired number of words landed just past the end of an object.
2664 // Find the start of the next object.
2665 cur_beg = m->find_obj_beg(cur_beg, search_end);
2666 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2667 return m->bit_to_addr(cur_beg);
2668 }
2669
2670 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2671 SpaceId src_space_id,
2672 size_t src_region_idx)
2673 {
2674 assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2675
2676 const SplitInfo& split_info = _space_info[src_space_id].split_info();
2677 if (split_info.dest_region_addr() == dest_addr) {
2678 // The partial object ending at the split point contains the first word to
2679 // be copied to dest_addr.
2680 return split_info.first_src_addr();
2681 }
2682
2683 const ParallelCompactData& sd = summary_data();
2684 ParMarkBitMap* const bitmap = mark_bitmap();
2685 const size_t RegionSize = ParallelCompactData::RegionSize;
2686
2687 assert(sd.is_region_aligned(dest_addr), "not aligned");
2688 const RegionData* const src_region_ptr = sd.region(src_region_idx);
2689 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2690 HeapWord* const src_region_destination = src_region_ptr->destination();
2691
2692 assert(dest_addr >= src_region_destination, "wrong src region");
2693 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2694
2695 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2696 HeapWord* const src_region_end = src_region_beg + RegionSize;
2697
2698 HeapWord* addr = src_region_beg;
2699 if (dest_addr == src_region_destination) {
2700 // Return the first live word in the source region.
2701 if (partial_obj_size == 0) {
2702 addr = bitmap->find_obj_beg(addr, src_region_end);
2703 assert(addr < src_region_end, "no objects start in src region");
2704 }
2705 return addr;
2706 }
2707
2708 // Must skip some live data.
2709 size_t words_to_skip = dest_addr - src_region_destination;
2710 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2711
2712 if (partial_obj_size >= words_to_skip) {
2713 // All the live words to skip are part of the partial object.
2714 addr += words_to_skip;
2715 if (partial_obj_size == words_to_skip) {
2716 // Find the first live word past the partial object.
2717 addr = bitmap->find_obj_beg(addr, src_region_end);
2718 assert(addr < src_region_end, "wrong src region");
2719 }
2720 return addr;
2721 }
2722
2723 // Skip over the partial object (if any).
2724 if (partial_obj_size != 0) {
2725 words_to_skip -= partial_obj_size;
2726 addr += partial_obj_size;
2727 }
2728
2729 // Skip over live words due to objects that start in the region.
2730 addr = skip_live_words(addr, src_region_end, words_to_skip);
2731 assert(addr < src_region_end, "wrong src region");
2732 return addr;
2733 }
2734
2735 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2736 SpaceId src_space_id,
2737 size_t beg_region,
2738 HeapWord* end_addr)
2739 {
2740 ParallelCompactData& sd = summary_data();
2741
2742 #ifdef ASSERT
2743 MutableSpace* const src_space = _space_info[src_space_id].space();
2744 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2745 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2746 "src_space_id does not match beg_addr");
2747 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2748 "src_space_id does not match end_addr");
2749 #endif // #ifdef ASSERT
2750
2751 RegionData* const beg = sd.region(beg_region);
2752 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2753
2754 // Regions up to new_top() are enqueued if they become available.
2755 HeapWord* const new_top = _space_info[src_space_id].new_top();
2756 RegionData* const enqueue_end =
2757 sd.addr_to_region_ptr(sd.region_align_up(new_top));
2758
2759 for (RegionData* cur = beg; cur < end; ++cur) {
2760 assert(cur->data_size() > 0, "region must have live data");
2761 cur->decrement_destination_count();
2762 if (cur < enqueue_end && cur->available() && cur->claim()) {
2763 cm->push_region(sd.region(cur));
2764 }
2765 }
2766 }
2767
2768 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2769 SpaceId& src_space_id,
2770 HeapWord*& src_space_top,
2771 HeapWord* end_addr)
2772 {
2773 typedef ParallelCompactData::RegionData RegionData;
2774
2775 ParallelCompactData& sd = PSParallelCompact::summary_data();
2776 const size_t region_size = ParallelCompactData::RegionSize;
2777
2778 size_t src_region_idx = 0;
2779
2780 // Skip empty regions (if any) up to the top of the space.
2781 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2782 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2783 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2784 const RegionData* const top_region_ptr =
2785 sd.addr_to_region_ptr(top_aligned_up);
2786 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2787 ++src_region_ptr;
2788 }
2789
2790 if (src_region_ptr < top_region_ptr) {
2791 // The next source region is in the current space. Update src_region_idx
2792 // and the source address to match src_region_ptr.
2793 src_region_idx = sd.region(src_region_ptr);
2794 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
2795 if (src_region_addr > closure.source()) {
2796 closure.set_source(src_region_addr);
2797 }
2798 return src_region_idx;
2799 }
2800
2801 // Switch to a new source space and find the first non-empty region.
2802 unsigned int space_id = src_space_id + 1;
2803 assert(space_id < last_space_id, "not enough spaces");
2804
2805 HeapWord* const destination = closure.destination();
2806
2807 do {
2808 MutableSpace* space = _space_info[space_id].space();
2809 HeapWord* const bottom = space->bottom();
2810 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
2811
2812 // Iterate over the spaces that do not compact into themselves.
2813 if (bottom_cp->destination() != bottom) {
2814 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
2815 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
2816
2817 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
2818 if (src_cp->live_obj_size() > 0) {
2819 // Found it.
2820 assert(src_cp->destination() == destination,
2821 "first live obj in the space must match the destination");
2822 assert(src_cp->partial_obj_size() == 0,
2823 "a space cannot begin with a partial obj");
2824
2825 src_space_id = SpaceId(space_id);
2826 src_space_top = space->top();
2827 const size_t src_region_idx = sd.region(src_cp);
2828 closure.set_source(sd.region_to_addr(src_region_idx));
2829 return src_region_idx;
2830 } else {
2831 assert(src_cp->data_size() == 0, "sanity");
2832 }
2833 }
2834 }
2835 } while (++space_id < last_space_id);
2836
2837 assert(false, "no source region was found");
2838 return 0;
2839 }
2840
2841 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
2842 {
2843 typedef ParMarkBitMap::IterationStatus IterationStatus;
2844 const size_t RegionSize = ParallelCompactData::RegionSize;
2845 ParMarkBitMap* const bitmap = mark_bitmap();
2846 ParallelCompactData& sd = summary_data();
2847 RegionData* const region_ptr = sd.region(region_idx);
2848
2849 // Get the items needed to construct the closure.
2850 HeapWord* dest_addr = sd.region_to_addr(region_idx);
2851 SpaceId dest_space_id = space_id(dest_addr);
2852 ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
2853 HeapWord* new_top = _space_info[dest_space_id].new_top();
2854 assert(dest_addr < new_top, "sanity");
2855 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
2856
2857 // Get the source region and related info.
2858 size_t src_region_idx = region_ptr->source_region();
2859 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2860 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2861
2862 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
2863 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2864
2865 // Adjust src_region_idx to prepare for decrementing destination counts (the
2866 // destination count is not decremented when a region is copied to itself).
2867 if (src_region_idx == region_idx) {
2868 src_region_idx += 1;
2869 }
2870
2871 if (bitmap->is_unmarked(closure.source())) {
2872 // The first source word is in the middle of an object; copy the remainder
2873 // of the object or as much as will fit. The fact that pointer updates were
2874 // deferred will be noted when the object header is processed.
2875 HeapWord* const old_src_addr = closure.source();
2876 closure.copy_partial_obj();
2877 if (closure.is_full()) {
2878 decrement_destination_counts(cm, src_space_id, src_region_idx,
2879 closure.source());
2880 region_ptr->set_deferred_obj_addr(NULL);
2881 region_ptr->set_completed();
2882 return;
2883 }
2884
2885 HeapWord* const end_addr = sd.region_align_down(closure.source());
2886 if (sd.region_align_down(old_src_addr) != end_addr) {
2887 // The partial object was copied from more than one source region.
2888 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2889
2890 // Move to the next source region, possibly switching spaces as well. All
2891 // args except end_addr may be modified.
2892 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2893 end_addr);
2894 }
2895 }
2896
2897 do {
2898 HeapWord* const cur_addr = closure.source();
2899 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2900 src_space_top);
2901 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
2902
2903 if (status == ParMarkBitMap::incomplete) {
2904 // The last obj that starts in the source region does not end in the
2905 // region.
2906 assert(closure.source() < end_addr, "sanity");
2907 HeapWord* const obj_beg = closure.source();
2908 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
2909 src_space_top);
2910 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
2911 if (obj_end < range_end) {
2912 // The end was found; the entire object will fit.
2913 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
2914 assert(status != ParMarkBitMap::would_overflow, "sanity");
2915 } else {
2916 // The end was not found; the object will not fit.
2917 assert(range_end < src_space_top, "obj cannot cross space boundary");
2918 status = ParMarkBitMap::would_overflow;
2919 }
2920 }
2921
2922 if (status == ParMarkBitMap::would_overflow) {
2923 // The last object did not fit. Note that interior oop updates were
2924 // deferred, then copy enough of the object to fill the region.
2925 region_ptr->set_deferred_obj_addr(closure.destination());
2926 status = closure.copy_until_full(); // copies from closure.source()
2927
2928 decrement_destination_counts(cm, src_space_id, src_region_idx,
2929 closure.source());
2930 region_ptr->set_completed();
2931 return;
2932 }
2933
2934 if (status == ParMarkBitMap::full) {
2935 decrement_destination_counts(cm, src_space_id, src_region_idx,
2936 closure.source());
2937 region_ptr->set_deferred_obj_addr(NULL);
2938 region_ptr->set_completed();
2939 return;
2940 }
2941
2942 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2943
2944 // Move to the next source region, possibly switching spaces as well. All
2945 // args except end_addr may be modified.
2946 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2947 end_addr);
2948 } while (true);
2949 }
2950
2951 void PSParallelCompact::fill_blocks(size_t region_idx)
2952 {
2953 // Fill in the block table elements for the specified region. Each block
2954 // table element holds the number of live words in the region that are to the
2955 // left of the first object that starts in the block. Thus only blocks in
2956 // which an object starts need to be filled.
2957 //
2958 // The algorithm scans the section of the bitmap that corresponds to the
2959 // region, keeping a running total of the live words. When an object start is
2960 // found, if it's the first to start in the block that contains it, the
2961 // current total is written to the block table element.
2962 const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
2963 const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
2964 const size_t RegionSize = ParallelCompactData::RegionSize;
2965
2966 ParallelCompactData& sd = summary_data();
2967 const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
2968 if (partial_obj_size >= RegionSize) {
2969 return; // No objects start in this region.
2970 }
2971
2972 // Ensure the first loop iteration decides that the block has changed.
2973 size_t cur_block = sd.block_count();
2974
2975 const ParMarkBitMap* const bitmap = mark_bitmap();
2976
2977 const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
2978 assert((size_t)1 << Log2BitsPerBlock ==
2979 bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
2980
2981 size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
2982 const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
2983 size_t live_bits = bitmap->words_to_bits(partial_obj_size);
2984 beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
2985 while (beg_bit < range_end) {
2986 const size_t new_block = beg_bit >> Log2BitsPerBlock;
2987 if (new_block != cur_block) {
2988 cur_block = new_block;
2989 sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
2990 }
2991
2992 const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
2993 if (end_bit < range_end - 1) {
2994 live_bits += end_bit - beg_bit + 1;
2995 beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
2996 } else {
2997 return;
2998 }
2999 }
3000 }
3001
3002 void
3003 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
3004 const MutableSpace* sp = space(space_id);
3005 if (sp->is_empty()) {
3006 return;
3007 }
3008
3009 ParallelCompactData& sd = PSParallelCompact::summary_data();
3010 ParMarkBitMap* const bitmap = mark_bitmap();
3011 HeapWord* const dp_addr = dense_prefix(space_id);
3012 HeapWord* beg_addr = sp->bottom();
3013 HeapWord* end_addr = sp->top();
3014
3015 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
3016
3017 const size_t beg_region = sd.addr_to_region_idx(beg_addr);
3018 const size_t dp_region = sd.addr_to_region_idx(dp_addr);
3019 if (beg_region < dp_region) {
3020 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
3021 }
3022
3023 // The destination of the first live object that starts in the region is one
3024 // past the end of the partial object entering the region (if any).
3025 HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3026 HeapWord* const new_top = _space_info[space_id].new_top();
3027 assert(new_top >= dest_addr, "bad new_top value");
3028 const size_t words = pointer_delta(new_top, dest_addr);
3029
3030 if (words > 0) {
3031 ObjectStartArray* start_array = _space_info[space_id].start_array();
3032 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3033
3034 ParMarkBitMap::IterationStatus status;
3035 status = bitmap->iterate(&closure, dest_addr, end_addr);
3036 assert(status == ParMarkBitMap::full, "iteration not complete");
3037 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3038 "live objects skipped because closure is full");
3039 }
3040 }
3041
3042 jlong PSParallelCompact::millis_since_last_gc() {
3043 // We need a monotonically non-decreasing time in ms but
3044 // os::javaTimeMillis() does not guarantee monotonicity.
3045 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3046 jlong ret_val = now - _time_of_last_gc;
3047 // XXX See note in genCollectedHeap::millis_since_last_gc().
3048 if (ret_val < 0) {
3049 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, ret_val);)
3050 return 0;
3051 }
3052 return ret_val;
3053 }
3054
3055 void PSParallelCompact::reset_millis_since_last_gc() {
3056 // We need a monotonically non-decreasing time in ms but
3057 // os::javaTimeMillis() does not guarantee monotonicity.
3058 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3059 }
3060
3061 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3062 {
3063 if (source() != destination()) {
3064 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3065 Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3066 }
3067 update_state(words_remaining());
3068 assert(is_full(), "sanity");
3069 return ParMarkBitMap::full;
3070 }
3071
3072 void MoveAndUpdateClosure::copy_partial_obj()
3073 {
3074 size_t words = words_remaining();
3075
3076 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3077 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3078 if (end_addr < range_end) {
3079 words = bitmap()->obj_size(source(), end_addr);
3080 }
3081
3082 // This test is necessary; if omitted, the pointer updates to a partial object
3083 // that crosses the dense prefix boundary could be overwritten.
3084 if (source() != destination()) {
3085 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3086 Copy::aligned_conjoint_words(source(), destination(), words);
3087 }
3088 update_state(words);
3089 }
3090
3091 void InstanceKlass::oop_pc_update_pointers(oop obj) {
3092 oop_oop_iterate_oop_maps<true>(obj, PSParallelCompact::adjust_pointer_closure());
3093 }
3094
3095 void InstanceMirrorKlass::oop_pc_update_pointers(oop obj) {
3096 InstanceKlass::oop_pc_update_pointers(obj);
3097
3098 oop_oop_iterate_statics<true>(obj, PSParallelCompact::adjust_pointer_closure());
3099 }
3100
3101 void InstanceClassLoaderKlass::oop_pc_update_pointers(oop obj) {
3102 InstanceKlass::oop_pc_update_pointers(obj);
3103 }
3104
3105 #ifdef ASSERT
3106 template <class T> static void trace_reference_gc(const char *s, oop obj,
3107 T* referent_addr,
3108 T* next_addr,
3109 T* discovered_addr) {
3110 if(TraceReferenceGC && PrintGCDetails) {
3111 gclog_or_tty->print_cr("%s obj " PTR_FORMAT, s, p2i(obj));
3112 gclog_or_tty->print_cr(" referent_addr/* " PTR_FORMAT " / "
3113 PTR_FORMAT, p2i(referent_addr),
3114 referent_addr ? p2i(oopDesc::load_decode_heap_oop(referent_addr)) : NULL);
3115 gclog_or_tty->print_cr(" next_addr/* " PTR_FORMAT " / "
3116 PTR_FORMAT, p2i(next_addr),
3117 next_addr ? p2i(oopDesc::load_decode_heap_oop(next_addr)) : NULL);
3118 gclog_or_tty->print_cr(" discovered_addr/* " PTR_FORMAT " / "
3119 PTR_FORMAT, p2i(discovered_addr),
3120 discovered_addr ? p2i(oopDesc::load_decode_heap_oop(discovered_addr)) : NULL);
3121 }
3122 }
3123 #endif
3124
3125 template <class T>
3126 static void oop_pc_update_pointers_specialized(oop obj) {
3127 T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj);
3128 PSParallelCompact::adjust_pointer(referent_addr);
3129 T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj);
3130 PSParallelCompact::adjust_pointer(next_addr);
3131 T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj);
3132 PSParallelCompact::adjust_pointer(discovered_addr);
3133 debug_only(trace_reference_gc("InstanceRefKlass::oop_update_ptrs", obj,
3134 referent_addr, next_addr, discovered_addr);)
3135 }
3136
3137 void InstanceRefKlass::oop_pc_update_pointers(oop obj) {
3138 InstanceKlass::oop_pc_update_pointers(obj);
3139
3140 if (UseCompressedOops) {
3141 oop_pc_update_pointers_specialized<narrowOop>(obj);
3142 } else {
3143 oop_pc_update_pointers_specialized<oop>(obj);
3144 }
3145 }
3146
3147 void ObjArrayKlass::oop_pc_update_pointers(oop obj) {
3148 assert(obj->is_objArray(), "obj must be obj array");
3149 oop_oop_iterate_elements<true>(objArrayOop(obj), PSParallelCompact::adjust_pointer_closure());
3150 }
3151
3152 void TypeArrayKlass::oop_pc_update_pointers(oop obj) {
3153 assert(obj->is_typeArray(),"must be a type array");
3154 }
3155
3156 ParMarkBitMapClosure::IterationStatus
3157 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3158 assert(destination() != NULL, "sanity");
3159 assert(bitmap()->obj_size(addr) == words, "bad size");
3160
3161 _source = addr;
3162 assert(PSParallelCompact::summary_data().calc_new_pointer(source()) ==
3163 destination(), "wrong destination");
3164
3165 if (words > words_remaining()) {
3166 return ParMarkBitMap::would_overflow;
3167 }
3168
3169 // The start_array must be updated even if the object is not moving.
3170 if (_start_array != NULL) {
3171 _start_array->allocate_block(destination());
3172 }
3173
3174 if (destination() != source()) {
3175 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3176 Copy::aligned_conjoint_words(source(), destination(), words);
3177 }
3178
3179 oop moved_oop = (oop) destination();
3180 compaction_manager()->update_contents(moved_oop);
3181 assert(moved_oop->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop));
3182
3183 update_state(words);
3184 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3185 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3186 }
3187
3188 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3189 ParCompactionManager* cm,
3190 PSParallelCompact::SpaceId space_id) :
3191 ParMarkBitMapClosure(mbm, cm),
3192 _space_id(space_id),
3193 _start_array(PSParallelCompact::start_array(space_id))
3194 {
3195 }
3196
3197 // Updates the references in the object to their new values.
3198 ParMarkBitMapClosure::IterationStatus
3199 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3200 do_addr(addr);
3201 return ParMarkBitMap::incomplete;
3202 }