1 /*
2 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/symbolTable.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "code/codeCache.hpp"
29 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp"
30 #include "gc_implementation/parallelScavenge/generationSizer.hpp"
31 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.inline.hpp"
32 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
33 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
34 #include "gc_implementation/parallelScavenge/psCompactionManager.inline.hpp"
35 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp"
36 #include "gc_implementation/parallelScavenge/psMarkSweepDecorator.hpp"
37 #include "gc_implementation/parallelScavenge/psOldGen.hpp"
38 #include "gc_implementation/parallelScavenge/psParallelCompact.hpp"
39 #include "gc_implementation/parallelScavenge/psPermGen.hpp"
40 #include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp"
41 #include "gc_implementation/parallelScavenge/psScavenge.hpp"
42 #include "gc_implementation/parallelScavenge/psYoungGen.hpp"
43 #include "gc_implementation/shared/isGCActiveMark.hpp"
44 #include "gc_interface/gcCause.hpp"
45 #include "memory/gcLocker.inline.hpp"
46 #include "memory/referencePolicy.hpp"
47 #include "memory/referenceProcessor.hpp"
48 #include "oops/methodDataOop.hpp"
49 #include "oops/oop.inline.hpp"
50 #include "oops/oop.pcgc.inline.hpp"
51 #include "runtime/fprofiler.hpp"
52 #include "runtime/safepoint.hpp"
53 #include "runtime/vmThread.hpp"
54 #include "services/management.hpp"
55 #include "services/memoryService.hpp"
56 #include "utilities/events.hpp"
57
58 #include <math.h>
59
60 // All sizes are in HeapWords.
61 const size_t ParallelCompactData::Log2RegionSize = 9; // 512 words
62 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
63 const size_t ParallelCompactData::RegionSizeBytes =
64 RegionSize << LogHeapWordSize;
65 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
66 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
67 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
68
69 const ParallelCompactData::RegionData::region_sz_t
70 ParallelCompactData::RegionData::dc_shift = 27;
71
72 const ParallelCompactData::RegionData::region_sz_t
73 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
74
75 const ParallelCompactData::RegionData::region_sz_t
76 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
77
78 const ParallelCompactData::RegionData::region_sz_t
79 ParallelCompactData::RegionData::los_mask = ~dc_mask;
80
81 const ParallelCompactData::RegionData::region_sz_t
82 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
83
84 const ParallelCompactData::RegionData::region_sz_t
85 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
86
87 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
88 bool PSParallelCompact::_print_phases = false;
89
90 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
91 klassOop PSParallelCompact::_updated_int_array_klass_obj = NULL;
92
93 double PSParallelCompact::_dwl_mean;
94 double PSParallelCompact::_dwl_std_dev;
95 double PSParallelCompact::_dwl_first_term;
96 double PSParallelCompact::_dwl_adjustment;
97 #ifdef ASSERT
98 bool PSParallelCompact::_dwl_initialized = false;
99 #endif // #ifdef ASSERT
100
101 #ifdef VALIDATE_MARK_SWEEP
102 GrowableArray<void*>* PSParallelCompact::_root_refs_stack = NULL;
103 GrowableArray<oop> * PSParallelCompact::_live_oops = NULL;
104 GrowableArray<oop> * PSParallelCompact::_live_oops_moved_to = NULL;
105 GrowableArray<size_t>* PSParallelCompact::_live_oops_size = NULL;
106 size_t PSParallelCompact::_live_oops_index = 0;
107 size_t PSParallelCompact::_live_oops_index_at_perm = 0;
108 GrowableArray<void*>* PSParallelCompact::_other_refs_stack = NULL;
109 GrowableArray<void*>* PSParallelCompact::_adjusted_pointers = NULL;
110 bool PSParallelCompact::_pointer_tracking = false;
111 bool PSParallelCompact::_root_tracking = true;
112
113 GrowableArray<HeapWord*>* PSParallelCompact::_cur_gc_live_oops = NULL;
114 GrowableArray<HeapWord*>* PSParallelCompact::_cur_gc_live_oops_moved_to = NULL;
115 GrowableArray<size_t> * PSParallelCompact::_cur_gc_live_oops_size = NULL;
116 GrowableArray<HeapWord*>* PSParallelCompact::_last_gc_live_oops = NULL;
117 GrowableArray<HeapWord*>* PSParallelCompact::_last_gc_live_oops_moved_to = NULL;
118 GrowableArray<size_t> * PSParallelCompact::_last_gc_live_oops_size = NULL;
119 #endif
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 #ifndef PRODUCT
188 const char* PSParallelCompact::space_names[] = {
189 "perm", "old ", "eden", "from", "to "
190 };
191
192 void PSParallelCompact::print_region_ranges()
193 {
194 tty->print_cr("space bottom top end new_top");
195 tty->print_cr("------ ---------- ---------- ---------- ----------");
196
197 for (unsigned int id = 0; id < last_space_id; ++id) {
198 const MutableSpace* space = _space_info[id].space();
199 tty->print_cr("%u %s "
200 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
201 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
202 id, space_names[id],
203 summary_data().addr_to_region_idx(space->bottom()),
204 summary_data().addr_to_region_idx(space->top()),
205 summary_data().addr_to_region_idx(space->end()),
206 summary_data().addr_to_region_idx(_space_info[id].new_top()));
207 }
208 }
209
210 void
211 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
212 {
213 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7)
214 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5)
215
216 ParallelCompactData& sd = PSParallelCompact::summary_data();
217 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
218 tty->print_cr(REGION_IDX_FORMAT " " PTR_FORMAT " "
219 REGION_IDX_FORMAT " " PTR_FORMAT " "
220 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
221 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
222 i, c->data_location(), dci, c->destination(),
223 c->partial_obj_size(), c->live_obj_size(),
224 c->data_size(), c->source_region(), c->destination_count());
225
226 #undef REGION_IDX_FORMAT
227 #undef REGION_DATA_FORMAT
228 }
229
230 void
231 print_generic_summary_data(ParallelCompactData& summary_data,
232 HeapWord* const beg_addr,
233 HeapWord* const end_addr)
234 {
235 size_t total_words = 0;
236 size_t i = summary_data.addr_to_region_idx(beg_addr);
237 const size_t last = summary_data.addr_to_region_idx(end_addr);
238 HeapWord* pdest = 0;
239
240 while (i <= last) {
241 ParallelCompactData::RegionData* c = summary_data.region(i);
242 if (c->data_size() != 0 || c->destination() != pdest) {
243 print_generic_summary_region(i, c);
244 total_words += c->data_size();
245 pdest = c->destination();
246 }
247 ++i;
248 }
249
250 tty->print_cr("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
251 }
252
253 void
254 print_generic_summary_data(ParallelCompactData& summary_data,
255 SpaceInfo* space_info)
256 {
257 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
258 const MutableSpace* space = space_info[id].space();
259 print_generic_summary_data(summary_data, space->bottom(),
260 MAX2(space->top(), space_info[id].new_top()));
261 }
262 }
263
264 void
265 print_initial_summary_region(size_t i,
266 const ParallelCompactData::RegionData* c,
267 bool newline = true)
268 {
269 tty->print(SIZE_FORMAT_W(5) " " PTR_FORMAT " "
270 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " "
271 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
272 i, c->destination(),
273 c->partial_obj_size(), c->live_obj_size(),
274 c->data_size(), c->source_region(), c->destination_count());
275 if (newline) tty->cr();
276 }
277
278 void
279 print_initial_summary_data(ParallelCompactData& summary_data,
280 const MutableSpace* space) {
281 if (space->top() == space->bottom()) {
282 return;
283 }
284
285 const size_t region_size = ParallelCompactData::RegionSize;
286 typedef ParallelCompactData::RegionData RegionData;
287 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
288 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
289 const RegionData* c = summary_data.region(end_region - 1);
290 HeapWord* end_addr = c->destination() + c->data_size();
291 const size_t live_in_space = pointer_delta(end_addr, space->bottom());
292
293 // Print (and count) the full regions at the beginning of the space.
294 size_t full_region_count = 0;
295 size_t i = summary_data.addr_to_region_idx(space->bottom());
296 while (i < end_region && summary_data.region(i)->data_size() == region_size) {
297 print_initial_summary_region(i, summary_data.region(i));
298 ++full_region_count;
299 ++i;
300 }
301
302 size_t live_to_right = live_in_space - full_region_count * region_size;
303
304 double max_reclaimed_ratio = 0.0;
305 size_t max_reclaimed_ratio_region = 0;
306 size_t max_dead_to_right = 0;
307 size_t max_live_to_right = 0;
308
309 // Print the 'reclaimed ratio' for regions while there is something live in
310 // the region or to the right of it. The remaining regions are empty (and
311 // uninteresting), and computing the ratio will result in division by 0.
312 while (i < end_region && live_to_right > 0) {
313 c = summary_data.region(i);
314 HeapWord* const region_addr = summary_data.region_to_addr(i);
315 const size_t used_to_right = pointer_delta(space->top(), region_addr);
316 const size_t dead_to_right = used_to_right - live_to_right;
317 const double reclaimed_ratio = double(dead_to_right) / live_to_right;
318
319 if (reclaimed_ratio > max_reclaimed_ratio) {
320 max_reclaimed_ratio = reclaimed_ratio;
321 max_reclaimed_ratio_region = i;
322 max_dead_to_right = dead_to_right;
323 max_live_to_right = live_to_right;
324 }
325
326 print_initial_summary_region(i, c, false);
327 tty->print_cr(" %12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
328 reclaimed_ratio, dead_to_right, live_to_right);
329
330 live_to_right -= c->data_size();
331 ++i;
332 }
333
334 // Any remaining regions are empty. Print one more if there is one.
335 if (i < end_region) {
336 print_initial_summary_region(i, summary_data.region(i));
337 }
338
339 tty->print_cr("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " "
340 "l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
341 max_reclaimed_ratio_region, max_dead_to_right,
342 max_live_to_right, max_reclaimed_ratio);
343 }
344
345 void
346 print_initial_summary_data(ParallelCompactData& summary_data,
347 SpaceInfo* space_info) {
348 unsigned int id = PSParallelCompact::perm_space_id;
349 const MutableSpace* space;
350 do {
351 space = space_info[id].space();
352 print_initial_summary_data(summary_data, space);
353 } while (++id < PSParallelCompact::eden_space_id);
354
355 do {
356 space = space_info[id].space();
357 print_generic_summary_data(summary_data, space->bottom(), space->top());
358 } while (++id < PSParallelCompact::last_space_id);
359 }
360 #endif // #ifndef PRODUCT
361
362 #ifdef ASSERT
363 size_t add_obj_count;
364 size_t add_obj_size;
365 size_t mark_bitmap_count;
366 size_t mark_bitmap_size;
367 #endif // #ifdef ASSERT
368
369 ParallelCompactData::ParallelCompactData()
370 {
371 _region_start = 0;
372
373 _region_vspace = 0;
374 _region_data = 0;
375 _region_count = 0;
376 }
377
378 bool ParallelCompactData::initialize(MemRegion covered_region)
379 {
380 _region_start = covered_region.start();
381 const size_t region_size = covered_region.word_size();
382 DEBUG_ONLY(_region_end = _region_start + region_size;)
383
384 assert(region_align_down(_region_start) == _region_start,
385 "region start not aligned");
386 assert((region_size & RegionSizeOffsetMask) == 0,
387 "region size not a multiple of RegionSize");
388
389 bool result = initialize_region_data(region_size);
390
391 return result;
392 }
393
394 PSVirtualSpace*
395 ParallelCompactData::create_vspace(size_t count, size_t element_size)
396 {
397 const size_t raw_bytes = count * element_size;
398 const size_t page_sz = os::page_size_for_region(raw_bytes, raw_bytes, 10);
399 const size_t granularity = os::vm_allocation_granularity();
400 const size_t bytes = align_size_up(raw_bytes, MAX2(page_sz, granularity));
401
402 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
403 MAX2(page_sz, granularity);
404 ReservedSpace rs(bytes, rs_align, rs_align > 0);
405 os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(),
406 rs.size());
407 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
408 if (vspace != 0) {
409 if (vspace->expand_by(bytes)) {
410 return vspace;
411 }
412 delete vspace;
413 // Release memory reserved in the space.
414 rs.release();
415 }
416
417 return 0;
418 }
419
420 bool ParallelCompactData::initialize_region_data(size_t region_size)
421 {
422 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
423 _region_vspace = create_vspace(count, sizeof(RegionData));
424 if (_region_vspace != 0) {
425 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
426 _region_count = count;
427 return true;
428 }
429 return false;
430 }
431
432 void ParallelCompactData::clear()
433 {
434 memset(_region_data, 0, _region_vspace->committed_size());
435 }
436
437 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
438 assert(beg_region <= _region_count, "beg_region out of range");
439 assert(end_region <= _region_count, "end_region out of range");
440
441 const size_t region_cnt = end_region - beg_region;
442 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
443 }
444
445 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
446 {
447 const RegionData* cur_cp = region(region_idx);
448 const RegionData* const end_cp = region(region_count() - 1);
449
450 HeapWord* result = region_to_addr(region_idx);
451 if (cur_cp < end_cp) {
452 do {
453 result += cur_cp->partial_obj_size();
454 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
455 }
456 return result;
457 }
458
459 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
460 {
461 const size_t obj_ofs = pointer_delta(addr, _region_start);
462 const size_t beg_region = obj_ofs >> Log2RegionSize;
463 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
464
465 DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
466 DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
467
468 if (beg_region == end_region) {
469 // All in one region.
470 _region_data[beg_region].add_live_obj(len);
471 return;
472 }
473
474 // First region.
475 const size_t beg_ofs = region_offset(addr);
476 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
477
478 klassOop klass = ((oop)addr)->klass();
479 // Middle regions--completely spanned by this object.
480 for (size_t region = beg_region + 1; region < end_region; ++region) {
481 _region_data[region].set_partial_obj_size(RegionSize);
482 _region_data[region].set_partial_obj_addr(addr);
483 }
484
485 // Last region.
486 const size_t end_ofs = region_offset(addr + len - 1);
487 _region_data[end_region].set_partial_obj_size(end_ofs + 1);
488 _region_data[end_region].set_partial_obj_addr(addr);
489 }
490
491 void
492 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
493 {
494 assert(region_offset(beg) == 0, "not RegionSize aligned");
495 assert(region_offset(end) == 0, "not RegionSize aligned");
496
497 size_t cur_region = addr_to_region_idx(beg);
498 const size_t end_region = addr_to_region_idx(end);
499 HeapWord* addr = beg;
500 while (cur_region < end_region) {
501 _region_data[cur_region].set_destination(addr);
502 _region_data[cur_region].set_destination_count(0);
503 _region_data[cur_region].set_source_region(cur_region);
504 _region_data[cur_region].set_data_location(addr);
505
506 // Update live_obj_size so the region appears completely full.
507 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
508 _region_data[cur_region].set_live_obj_size(live_size);
509
510 ++cur_region;
511 addr += RegionSize;
512 }
513 }
514
515 // Find the point at which a space can be split and, if necessary, record the
516 // split point.
517 //
518 // If the current src region (which overflowed the destination space) doesn't
519 // have a partial object, the split point is at the beginning of the current src
520 // region (an "easy" split, no extra bookkeeping required).
521 //
522 // If the current src region has a partial object, the split point is in the
523 // region where that partial object starts (call it the split_region). If
524 // split_region has a partial object, then the split point is just after that
525 // partial object (a "hard" split where we have to record the split data and
526 // zero the partial_obj_size field). With a "hard" split, we know that the
527 // partial_obj ends within split_region because the partial object that caused
528 // the overflow starts in split_region. If split_region doesn't have a partial
529 // obj, then the split is at the beginning of split_region (another "easy"
530 // split).
531 HeapWord*
532 ParallelCompactData::summarize_split_space(size_t src_region,
533 SplitInfo& split_info,
534 HeapWord* destination,
535 HeapWord* target_end,
536 HeapWord** target_next)
537 {
538 assert(destination <= target_end, "sanity");
539 assert(destination + _region_data[src_region].data_size() > target_end,
540 "region should not fit into target space");
541 assert(is_region_aligned(target_end), "sanity");
542
543 size_t split_region = src_region;
544 HeapWord* split_destination = destination;
545 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
546
547 if (destination + partial_obj_size > target_end) {
548 // The split point is just after the partial object (if any) in the
549 // src_region that contains the start of the object that overflowed the
550 // destination space.
551 //
552 // Find the start of the "overflow" object and set split_region to the
553 // region containing it.
554 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
555 split_region = addr_to_region_idx(overflow_obj);
556
557 // Clear the source_region field of all destination regions whose first word
558 // came from data after the split point (a non-null source_region field
559 // implies a region must be filled).
560 //
561 // An alternative to the simple loop below: clear during post_compact(),
562 // which uses memcpy instead of individual stores, and is easy to
563 // parallelize. (The downside is that it clears the entire RegionData
564 // object as opposed to just one field.)
565 //
566 // post_compact() would have to clear the summary data up to the highest
567 // address that was written during the summary phase, which would be
568 //
569 // max(top, max(new_top, clear_top))
570 //
571 // where clear_top is a new field in SpaceInfo. Would have to set clear_top
572 // to target_end.
573 const RegionData* const sr = region(split_region);
574 const size_t beg_idx =
575 addr_to_region_idx(region_align_up(sr->destination() +
576 sr->partial_obj_size()));
577 const size_t end_idx = addr_to_region_idx(target_end);
578
579 if (TraceParallelOldGCSummaryPhase) {
580 gclog_or_tty->print_cr("split: clearing source_region field in ["
581 SIZE_FORMAT ", " SIZE_FORMAT ")",
582 beg_idx, end_idx);
583 }
584 for (size_t idx = beg_idx; idx < end_idx; ++idx) {
585 _region_data[idx].set_source_region(0);
586 }
587
588 // Set split_destination and partial_obj_size to reflect the split region.
589 split_destination = sr->destination();
590 partial_obj_size = sr->partial_obj_size();
591 }
592
593 // The split is recorded only if a partial object extends onto the region.
594 if (partial_obj_size != 0) {
595 _region_data[split_region].set_partial_obj_size(0);
596 split_info.record(split_region, partial_obj_size, split_destination);
597 }
598
599 // Setup the continuation addresses.
600 *target_next = split_destination + partial_obj_size;
601 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
602
603 if (TraceParallelOldGCSummaryPhase) {
604 const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
605 gclog_or_tty->print_cr("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT
606 " pos=" SIZE_FORMAT,
607 split_type, source_next, split_region,
608 partial_obj_size);
609 gclog_or_tty->print_cr("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT
610 " tn=" PTR_FORMAT,
611 split_type, split_destination,
612 addr_to_region_idx(split_destination),
613 *target_next);
614
615 if (partial_obj_size != 0) {
616 HeapWord* const po_beg = split_info.destination();
617 HeapWord* const po_end = po_beg + split_info.partial_obj_size();
618 gclog_or_tty->print_cr("%s split: "
619 "po_beg=" PTR_FORMAT " " SIZE_FORMAT " "
620 "po_end=" PTR_FORMAT " " SIZE_FORMAT,
621 split_type,
622 po_beg, addr_to_region_idx(po_beg),
623 po_end, addr_to_region_idx(po_end));
624 }
625 }
626
627 return source_next;
628 }
629
630 bool ParallelCompactData::summarize(SplitInfo& split_info,
631 HeapWord* source_beg, HeapWord* source_end,
632 HeapWord** source_next,
633 HeapWord* target_beg, HeapWord* target_end,
634 HeapWord** target_next)
635 {
636 if (TraceParallelOldGCSummaryPhase) {
637 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
638 tty->print_cr("sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
639 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
640 source_beg, source_end, source_next_val,
641 target_beg, target_end, *target_next);
642 }
643
644 size_t cur_region = addr_to_region_idx(source_beg);
645 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
646
647 HeapWord *dest_addr = target_beg;
648 while (cur_region < end_region) {
649 // The destination must be set even if the region has no data.
650 _region_data[cur_region].set_destination(dest_addr);
651
652 size_t words = _region_data[cur_region].data_size();
653 if (words > 0) {
654 // If cur_region does not fit entirely into the target space, find a point
655 // at which the source space can be 'split' so that part is copied to the
656 // target space and the rest is copied elsewhere.
657 if (dest_addr + words > target_end) {
658 assert(source_next != NULL, "source_next is NULL when splitting");
659 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
660 target_end, target_next);
661 return false;
662 }
663
664 // Compute the destination_count for cur_region, and if necessary, update
665 // source_region for a destination region. The source_region field is
666 // updated if cur_region is the first (left-most) region to be copied to a
667 // destination region.
668 //
669 // The destination_count calculation is a bit subtle. A region that has
670 // data that compacts into itself does not count itself as a destination.
671 // This maintains the invariant that a zero count means the region is
672 // available and can be claimed and then filled.
673 uint destination_count = 0;
674 if (split_info.is_split(cur_region)) {
675 // The current region has been split: the partial object will be copied
676 // to one destination space and the remaining data will be copied to
677 // another destination space. Adjust the initial destination_count and,
678 // if necessary, set the source_region field if the partial object will
679 // cross a destination region boundary.
680 destination_count = split_info.destination_count();
681 if (destination_count == 2) {
682 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
683 _region_data[dest_idx].set_source_region(cur_region);
684 }
685 }
686
687 HeapWord* const last_addr = dest_addr + words - 1;
688 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
689 const size_t dest_region_2 = addr_to_region_idx(last_addr);
690
691 // Initially assume that the destination regions will be the same and
692 // adjust the value below if necessary. Under this assumption, if
693 // cur_region == dest_region_2, then cur_region will be compacted
694 // completely into itself.
695 destination_count += cur_region == dest_region_2 ? 0 : 1;
696 if (dest_region_1 != dest_region_2) {
697 // Destination regions differ; adjust destination_count.
698 destination_count += 1;
699 // Data from cur_region will be copied to the start of dest_region_2.
700 _region_data[dest_region_2].set_source_region(cur_region);
701 } else if (region_offset(dest_addr) == 0) {
702 // Data from cur_region will be copied to the start of the destination
703 // region.
704 _region_data[dest_region_1].set_source_region(cur_region);
705 }
706
707 _region_data[cur_region].set_destination_count(destination_count);
708 _region_data[cur_region].set_data_location(region_to_addr(cur_region));
709 dest_addr += words;
710 }
711
712 ++cur_region;
713 }
714
715 *target_next = dest_addr;
716 return true;
717 }
718
719 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) {
720 assert(addr != NULL, "Should detect NULL oop earlier");
721 assert(PSParallelCompact::gc_heap()->is_in(addr), "addr not in heap");
722 #ifdef ASSERT
723 if (PSParallelCompact::mark_bitmap()->is_unmarked(addr)) {
724 gclog_or_tty->print_cr("calc_new_pointer:: addr " PTR_FORMAT, addr);
725 }
726 #endif
727 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "obj not marked");
728
729 // Region covering the object.
730 size_t region_index = addr_to_region_idx(addr);
731 const RegionData* const region_ptr = region(region_index);
732 HeapWord* const region_addr = region_align_down(addr);
733
734 assert(addr < region_addr + RegionSize, "Region does not cover object");
735 assert(addr_to_region_ptr(region_addr) == region_ptr, "sanity check");
736
737 HeapWord* result = region_ptr->destination();
738
739 // If all the data in the region is live, then the new location of the object
740 // can be calculated from the destination of the region plus the offset of the
741 // object in the region.
742 if (region_ptr->data_size() == RegionSize) {
743 result += pointer_delta(addr, region_addr);
744 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result);)
745 return result;
746 }
747
748 // The new location of the object is
749 // region destination +
750 // size of the partial object extending onto the region +
751 // sizes of the live objects in the Region that are to the left of addr
752 const size_t partial_obj_size = region_ptr->partial_obj_size();
753 HeapWord* const search_start = region_addr + partial_obj_size;
754
755 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
756 size_t live_to_left = bitmap->live_words_in_range(search_start, oop(addr));
757
758 result += partial_obj_size + live_to_left;
759 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result);)
760 return result;
761 }
762
763 klassOop ParallelCompactData::calc_new_klass(klassOop old_klass) {
764 klassOop updated_klass;
765 if (PSParallelCompact::should_update_klass(old_klass)) {
766 updated_klass = (klassOop) calc_new_pointer(old_klass);
767 } else {
768 updated_klass = old_klass;
769 }
770
771 return updated_klass;
772 }
773
774 #ifdef ASSERT
775 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
776 {
777 const size_t* const beg = (const size_t*)vspace->committed_low_addr();
778 const size_t* const end = (const size_t*)vspace->committed_high_addr();
779 for (const size_t* p = beg; p < end; ++p) {
780 assert(*p == 0, "not zero");
781 }
782 }
783
784 void ParallelCompactData::verify_clear()
785 {
786 verify_clear(_region_vspace);
787 }
788 #endif // #ifdef ASSERT
789
790 #ifdef NOT_PRODUCT
791 ParallelCompactData::RegionData* debug_region(size_t region_index) {
792 ParallelCompactData& sd = PSParallelCompact::summary_data();
793 return sd.region(region_index);
794 }
795 #endif
796
797 elapsedTimer PSParallelCompact::_accumulated_time;
798 unsigned int PSParallelCompact::_total_invocations = 0;
799 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
800 jlong PSParallelCompact::_time_of_last_gc = 0;
801 CollectorCounters* PSParallelCompact::_counters = NULL;
802 ParMarkBitMap PSParallelCompact::_mark_bitmap;
803 ParallelCompactData PSParallelCompact::_summary_data;
804
805 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
806
807 void PSParallelCompact::IsAliveClosure::do_object(oop p) { ShouldNotReachHere(); }
808 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
809
810 void PSParallelCompact::KeepAliveClosure::do_oop(oop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
811 void PSParallelCompact::KeepAliveClosure::do_oop(narrowOop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
812
813 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_root_pointer_closure(true);
814 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_pointer_closure(false);
815
816 void PSParallelCompact::AdjustPointerClosure::do_oop(oop* p) { adjust_pointer(p, _is_root); }
817 void PSParallelCompact::AdjustPointerClosure::do_oop(narrowOop* p) { adjust_pointer(p, _is_root); }
818
819 void PSParallelCompact::FollowStackClosure::do_void() { _compaction_manager->follow_marking_stacks(); }
820
821 void PSParallelCompact::MarkAndPushClosure::do_oop(oop* p) { mark_and_push(_compaction_manager, p); }
822 void PSParallelCompact::MarkAndPushClosure::do_oop(narrowOop* p) { mark_and_push(_compaction_manager, p); }
823
824 void PSParallelCompact::post_initialize() {
825 ParallelScavengeHeap* heap = gc_heap();
826 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
827
828 MemRegion mr = heap->reserved_region();
829 _ref_processor = ReferenceProcessor::create_ref_processor(
830 mr, // span
831 true, // atomic_discovery
832 true, // mt_discovery
833 &_is_alive_closure,
834 ParallelGCThreads,
835 ParallelRefProcEnabled);
836 _counters = new CollectorCounters("PSParallelCompact", 1);
837
838 // Initialize static fields in ParCompactionManager.
839 ParCompactionManager::initialize(mark_bitmap());
840 }
841
842 bool PSParallelCompact::initialize() {
843 ParallelScavengeHeap* heap = gc_heap();
844 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
845 MemRegion mr = heap->reserved_region();
846
847 // Was the old gen get allocated successfully?
848 if (!heap->old_gen()->is_allocated()) {
849 return false;
850 }
851
852 initialize_space_info();
853 initialize_dead_wood_limiter();
854
855 if (!_mark_bitmap.initialize(mr)) {
856 vm_shutdown_during_initialization("Unable to allocate bit map for "
857 "parallel garbage collection for the requested heap size.");
858 return false;
859 }
860
861 if (!_summary_data.initialize(mr)) {
862 vm_shutdown_during_initialization("Unable to allocate tables for "
863 "parallel garbage collection for the requested heap size.");
864 return false;
865 }
866
867 return true;
868 }
869
870 void PSParallelCompact::initialize_space_info()
871 {
872 memset(&_space_info, 0, sizeof(_space_info));
873
874 ParallelScavengeHeap* heap = gc_heap();
875 PSYoungGen* young_gen = heap->young_gen();
876 MutableSpace* perm_space = heap->perm_gen()->object_space();
877
878 _space_info[perm_space_id].set_space(perm_space);
879 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
880 _space_info[eden_space_id].set_space(young_gen->eden_space());
881 _space_info[from_space_id].set_space(young_gen->from_space());
882 _space_info[to_space_id].set_space(young_gen->to_space());
883
884 _space_info[perm_space_id].set_start_array(heap->perm_gen()->start_array());
885 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
886
887 _space_info[perm_space_id].set_min_dense_prefix(perm_space->top());
888 if (TraceParallelOldGCDensePrefix) {
889 tty->print_cr("perm min_dense_prefix=" PTR_FORMAT,
890 _space_info[perm_space_id].min_dense_prefix());
891 }
892 }
893
894 void PSParallelCompact::initialize_dead_wood_limiter()
895 {
896 const size_t max = 100;
897 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
898 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
899 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
900 DEBUG_ONLY(_dwl_initialized = true;)
901 _dwl_adjustment = normal_distribution(1.0);
902 }
903
904 // Simple class for storing info about the heap at the start of GC, to be used
905 // after GC for comparison/printing.
906 class PreGCValues {
907 public:
908 PreGCValues() { }
909 PreGCValues(ParallelScavengeHeap* heap) { fill(heap); }
910
911 void fill(ParallelScavengeHeap* heap) {
912 _heap_used = heap->used();
913 _young_gen_used = heap->young_gen()->used_in_bytes();
914 _old_gen_used = heap->old_gen()->used_in_bytes();
915 _perm_gen_used = heap->perm_gen()->used_in_bytes();
916 };
917
918 size_t heap_used() const { return _heap_used; }
919 size_t young_gen_used() const { return _young_gen_used; }
920 size_t old_gen_used() const { return _old_gen_used; }
921 size_t perm_gen_used() const { return _perm_gen_used; }
922
923 private:
924 size_t _heap_used;
925 size_t _young_gen_used;
926 size_t _old_gen_used;
927 size_t _perm_gen_used;
928 };
929
930 void
931 PSParallelCompact::clear_data_covering_space(SpaceId id)
932 {
933 // At this point, top is the value before GC, new_top() is the value that will
934 // be set at the end of GC. The marking bitmap is cleared to top; nothing
935 // should be marked above top. The summary data is cleared to the larger of
936 // top & new_top.
937 MutableSpace* const space = _space_info[id].space();
938 HeapWord* const bot = space->bottom();
939 HeapWord* const top = space->top();
940 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
941
942 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
943 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
944 _mark_bitmap.clear_range(beg_bit, end_bit);
945
946 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
947 const size_t end_region =
948 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
949 _summary_data.clear_range(beg_region, end_region);
950
951 // Clear the data used to 'split' regions.
952 SplitInfo& split_info = _space_info[id].split_info();
953 if (split_info.is_valid()) {
954 split_info.clear();
955 }
956 DEBUG_ONLY(split_info.verify_clear();)
957 }
958
959 void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values)
960 {
961 // Update the from & to space pointers in space_info, since they are swapped
962 // at each young gen gc. Do the update unconditionally (even though a
963 // promotion failure does not swap spaces) because an unknown number of minor
964 // collections will have swapped the spaces an unknown number of times.
965 TraceTime tm("pre compact", print_phases(), true, gclog_or_tty);
966 ParallelScavengeHeap* heap = gc_heap();
967 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
968 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
969
970 pre_gc_values->fill(heap);
971
972 ParCompactionManager::reset();
973 NOT_PRODUCT(_mark_bitmap.reset_counters());
974 DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
975 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
976
977 // Increment the invocation count
978 heap->increment_total_collections(true);
979
980 // We need to track unique mark sweep invocations as well.
981 _total_invocations++;
982
983 if (PrintHeapAtGC) {
984 Universe::print_heap_before_gc();
985 }
986
987 // Fill in TLABs
988 heap->accumulate_statistics_all_tlabs();
989 heap->ensure_parsability(true); // retire TLABs
990
991 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
992 HandleMark hm; // Discard invalid handles created during verification
993 gclog_or_tty->print(" VerifyBeforeGC:");
994 Universe::verify(true);
995 }
996
997 // Verify object start arrays
998 if (VerifyObjectStartArray &&
999 VerifyBeforeGC) {
1000 heap->old_gen()->verify_object_start_array();
1001 heap->perm_gen()->verify_object_start_array();
1002 }
1003
1004 DEBUG_ONLY(mark_bitmap()->verify_clear();)
1005 DEBUG_ONLY(summary_data().verify_clear();)
1006
1007 // Have worker threads release resources the next time they run a task.
1008 gc_task_manager()->release_all_resources();
1009 }
1010
1011 void PSParallelCompact::post_compact()
1012 {
1013 TraceTime tm("post compact", print_phases(), true, gclog_or_tty);
1014
1015 for (unsigned int id = perm_space_id; id < last_space_id; ++id) {
1016 // Clear the marking bitmap, summary data and split info.
1017 clear_data_covering_space(SpaceId(id));
1018 // Update top(). Must be done after clearing the bitmap and summary data.
1019 _space_info[id].publish_new_top();
1020 }
1021
1022 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1023 MutableSpace* const from_space = _space_info[from_space_id].space();
1024 MutableSpace* const to_space = _space_info[to_space_id].space();
1025
1026 ParallelScavengeHeap* heap = gc_heap();
1027 bool eden_empty = eden_space->is_empty();
1028 if (!eden_empty) {
1029 eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1030 heap->young_gen(), heap->old_gen());
1031 }
1032
1033 // Update heap occupancy information which is used as input to the soft ref
1034 // clearing policy at the next gc.
1035 Universe::update_heap_info_at_gc();
1036
1037 bool young_gen_empty = eden_empty && from_space->is_empty() &&
1038 to_space->is_empty();
1039
1040 BarrierSet* bs = heap->barrier_set();
1041 if (bs->is_a(BarrierSet::ModRef)) {
1042 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
1043 MemRegion old_mr = heap->old_gen()->reserved();
1044 MemRegion perm_mr = heap->perm_gen()->reserved();
1045 assert(perm_mr.end() <= old_mr.start(), "Generations out of order");
1046
1047 if (young_gen_empty) {
1048 modBS->clear(MemRegion(perm_mr.start(), old_mr.end()));
1049 } else {
1050 modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end()));
1051 }
1052 }
1053
1054 Threads::gc_epilogue();
1055 CodeCache::gc_epilogue();
1056
1057 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1058
1059 ref_processor()->enqueue_discovered_references(NULL);
1060
1061 if (ZapUnusedHeapArea) {
1062 heap->gen_mangle_unused_area();
1063 }
1064
1065 // Update time of last GC
1066 reset_millis_since_last_gc();
1067 }
1068
1069 HeapWord*
1070 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1071 bool maximum_compaction)
1072 {
1073 const size_t region_size = ParallelCompactData::RegionSize;
1074 const ParallelCompactData& sd = summary_data();
1075
1076 const MutableSpace* const space = _space_info[id].space();
1077 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1078 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1079 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1080
1081 // Skip full regions at the beginning of the space--they are necessarily part
1082 // of the dense prefix.
1083 size_t full_count = 0;
1084 const RegionData* cp;
1085 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1086 ++full_count;
1087 }
1088
1089 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1090 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1091 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1092 if (maximum_compaction || cp == end_cp || interval_ended) {
1093 _maximum_compaction_gc_num = total_invocations();
1094 return sd.region_to_addr(cp);
1095 }
1096
1097 HeapWord* const new_top = _space_info[id].new_top();
1098 const size_t space_live = pointer_delta(new_top, space->bottom());
1099 const size_t space_used = space->used_in_words();
1100 const size_t space_capacity = space->capacity_in_words();
1101
1102 const double cur_density = double(space_live) / space_capacity;
1103 const double deadwood_density =
1104 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1105 const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1106
1107 if (TraceParallelOldGCDensePrefix) {
1108 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1109 cur_density, deadwood_density, deadwood_goal);
1110 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1111 "space_cap=" SIZE_FORMAT,
1112 space_live, space_used,
1113 space_capacity);
1114 }
1115
1116 // XXX - Use binary search?
1117 HeapWord* dense_prefix = sd.region_to_addr(cp);
1118 const RegionData* full_cp = cp;
1119 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1120 while (cp < end_cp) {
1121 HeapWord* region_destination = cp->destination();
1122 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1123 if (TraceParallelOldGCDensePrefix && Verbose) {
1124 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1125 "dp=" SIZE_FORMAT_W(8) " " "cdw=" SIZE_FORMAT_W(8),
1126 sd.region(cp), region_destination,
1127 dense_prefix, cur_deadwood);
1128 }
1129
1130 if (cur_deadwood >= deadwood_goal) {
1131 // Found the region that has the correct amount of deadwood to the left.
1132 // This typically occurs after crossing a fairly sparse set of regions, so
1133 // iterate backwards over those sparse regions, looking for the region
1134 // that has the lowest density of live objects 'to the right.'
1135 size_t space_to_left = sd.region(cp) * region_size;
1136 size_t live_to_left = space_to_left - cur_deadwood;
1137 size_t space_to_right = space_capacity - space_to_left;
1138 size_t live_to_right = space_live - live_to_left;
1139 double density_to_right = double(live_to_right) / space_to_right;
1140 while (cp > full_cp) {
1141 --cp;
1142 const size_t prev_region_live_to_right = live_to_right -
1143 cp->data_size();
1144 const size_t prev_region_space_to_right = space_to_right + region_size;
1145 double prev_region_density_to_right =
1146 double(prev_region_live_to_right) / prev_region_space_to_right;
1147 if (density_to_right <= prev_region_density_to_right) {
1148 return dense_prefix;
1149 }
1150 if (TraceParallelOldGCDensePrefix && Verbose) {
1151 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1152 "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1153 prev_region_density_to_right);
1154 }
1155 dense_prefix -= region_size;
1156 live_to_right = prev_region_live_to_right;
1157 space_to_right = prev_region_space_to_right;
1158 density_to_right = prev_region_density_to_right;
1159 }
1160 return dense_prefix;
1161 }
1162
1163 dense_prefix += region_size;
1164 ++cp;
1165 }
1166
1167 return dense_prefix;
1168 }
1169
1170 #ifndef PRODUCT
1171 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1172 const SpaceId id,
1173 const bool maximum_compaction,
1174 HeapWord* const addr)
1175 {
1176 const size_t region_idx = summary_data().addr_to_region_idx(addr);
1177 RegionData* const cp = summary_data().region(region_idx);
1178 const MutableSpace* const space = _space_info[id].space();
1179 HeapWord* const new_top = _space_info[id].new_top();
1180
1181 const size_t space_live = pointer_delta(new_top, space->bottom());
1182 const size_t dead_to_left = pointer_delta(addr, cp->destination());
1183 const size_t space_cap = space->capacity_in_words();
1184 const double dead_to_left_pct = double(dead_to_left) / space_cap;
1185 const size_t live_to_right = new_top - cp->destination();
1186 const size_t dead_to_right = space->top() - addr - live_to_right;
1187
1188 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1189 "spl=" SIZE_FORMAT " "
1190 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1191 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1192 " ratio=%10.8f",
1193 algorithm, addr, region_idx,
1194 space_live,
1195 dead_to_left, dead_to_left_pct,
1196 dead_to_right, live_to_right,
1197 double(dead_to_right) / live_to_right);
1198 }
1199 #endif // #ifndef PRODUCT
1200
1201 // Return a fraction indicating how much of the generation can be treated as
1202 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution
1203 // based on the density of live objects in the generation to determine a limit,
1204 // which is then adjusted so the return value is min_percent when the density is
1205 // 1.
1206 //
1207 // The following table shows some return values for a different values of the
1208 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1209 // min_percent is 1.
1210 //
1211 // fraction allowed as dead wood
1212 // -----------------------------------------------------------------
1213 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1214 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1215 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1216 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1217 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1218 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1219 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1220 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1221 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1222 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1223 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1224 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1225 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1226 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1227 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1228 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1229 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1230 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1231 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1232 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1233 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1234 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1235 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1236
1237 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1238 {
1239 assert(_dwl_initialized, "uninitialized");
1240
1241 // The raw limit is the value of the normal distribution at x = density.
1242 const double raw_limit = normal_distribution(density);
1243
1244 // Adjust the raw limit so it becomes the minimum when the density is 1.
1245 //
1246 // First subtract the adjustment value (which is simply the precomputed value
1247 // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1248 // Then add the minimum value, so the minimum is returned when the density is
1249 // 1. Finally, prevent negative values, which occur when the mean is not 0.5.
1250 const double min = double(min_percent) / 100.0;
1251 const double limit = raw_limit - _dwl_adjustment + min;
1252 return MAX2(limit, 0.0);
1253 }
1254
1255 ParallelCompactData::RegionData*
1256 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1257 const RegionData* end)
1258 {
1259 const size_t region_size = ParallelCompactData::RegionSize;
1260 ParallelCompactData& sd = summary_data();
1261 size_t left = sd.region(beg);
1262 size_t right = end > beg ? sd.region(end) - 1 : left;
1263
1264 // Binary search.
1265 while (left < right) {
1266 // Equivalent to (left + right) / 2, but does not overflow.
1267 const size_t middle = left + (right - left) / 2;
1268 RegionData* const middle_ptr = sd.region(middle);
1269 HeapWord* const dest = middle_ptr->destination();
1270 HeapWord* const addr = sd.region_to_addr(middle);
1271 assert(dest != NULL, "sanity");
1272 assert(dest <= addr, "must move left");
1273
1274 if (middle > left && dest < addr) {
1275 right = middle - 1;
1276 } else if (middle < right && middle_ptr->data_size() == region_size) {
1277 left = middle + 1;
1278 } else {
1279 return middle_ptr;
1280 }
1281 }
1282 return sd.region(left);
1283 }
1284
1285 ParallelCompactData::RegionData*
1286 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1287 const RegionData* end,
1288 size_t dead_words)
1289 {
1290 ParallelCompactData& sd = summary_data();
1291 size_t left = sd.region(beg);
1292 size_t right = end > beg ? sd.region(end) - 1 : left;
1293
1294 // Binary search.
1295 while (left < right) {
1296 // Equivalent to (left + right) / 2, but does not overflow.
1297 const size_t middle = left + (right - left) / 2;
1298 RegionData* const middle_ptr = sd.region(middle);
1299 HeapWord* const dest = middle_ptr->destination();
1300 HeapWord* const addr = sd.region_to_addr(middle);
1301 assert(dest != NULL, "sanity");
1302 assert(dest <= addr, "must move left");
1303
1304 const size_t dead_to_left = pointer_delta(addr, dest);
1305 if (middle > left && dead_to_left > dead_words) {
1306 right = middle - 1;
1307 } else if (middle < right && dead_to_left < dead_words) {
1308 left = middle + 1;
1309 } else {
1310 return middle_ptr;
1311 }
1312 }
1313 return sd.region(left);
1314 }
1315
1316 // The result is valid during the summary phase, after the initial summarization
1317 // of each space into itself, and before final summarization.
1318 inline double
1319 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1320 HeapWord* const bottom,
1321 HeapWord* const top,
1322 HeapWord* const new_top)
1323 {
1324 ParallelCompactData& sd = summary_data();
1325
1326 assert(cp != NULL, "sanity");
1327 assert(bottom != NULL, "sanity");
1328 assert(top != NULL, "sanity");
1329 assert(new_top != NULL, "sanity");
1330 assert(top >= new_top, "summary data problem?");
1331 assert(new_top > bottom, "space is empty; should not be here");
1332 assert(new_top >= cp->destination(), "sanity");
1333 assert(top >= sd.region_to_addr(cp), "sanity");
1334
1335 HeapWord* const destination = cp->destination();
1336 const size_t dense_prefix_live = pointer_delta(destination, bottom);
1337 const size_t compacted_region_live = pointer_delta(new_top, destination);
1338 const size_t compacted_region_used = pointer_delta(top,
1339 sd.region_to_addr(cp));
1340 const size_t reclaimable = compacted_region_used - compacted_region_live;
1341
1342 const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1343 return double(reclaimable) / divisor;
1344 }
1345
1346 // Return the address of the end of the dense prefix, a.k.a. the start of the
1347 // compacted region. The address is always on a region boundary.
1348 //
1349 // Completely full regions at the left are skipped, since no compaction can
1350 // occur in those regions. Then the maximum amount of dead wood to allow is
1351 // computed, based on the density (amount live / capacity) of the generation;
1352 // the region with approximately that amount of dead space to the left is
1353 // identified as the limit region. Regions between the last completely full
1354 // region and the limit region are scanned and the one that has the best
1355 // (maximum) reclaimed_ratio() is selected.
1356 HeapWord*
1357 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1358 bool maximum_compaction)
1359 {
1360 if (ParallelOldGCSplitALot) {
1361 if (_space_info[id].dense_prefix() != _space_info[id].space()->bottom()) {
1362 // The value was chosen to provoke splitting a young gen space; use it.
1363 return _space_info[id].dense_prefix();
1364 }
1365 }
1366
1367 const size_t region_size = ParallelCompactData::RegionSize;
1368 const ParallelCompactData& sd = summary_data();
1369
1370 const MutableSpace* const space = _space_info[id].space();
1371 HeapWord* const top = space->top();
1372 HeapWord* const top_aligned_up = sd.region_align_up(top);
1373 HeapWord* const new_top = _space_info[id].new_top();
1374 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1375 HeapWord* const bottom = space->bottom();
1376 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1377 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1378 const RegionData* const new_top_cp =
1379 sd.addr_to_region_ptr(new_top_aligned_up);
1380
1381 // Skip full regions at the beginning of the space--they are necessarily part
1382 // of the dense prefix.
1383 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1384 assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1385 space->is_empty(), "no dead space allowed to the left");
1386 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1387 "region must have dead space");
1388
1389 // The gc number is saved whenever a maximum compaction is done, and used to
1390 // determine when the maximum compaction interval has expired. This avoids
1391 // successive max compactions for different reasons.
1392 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1393 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1394 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1395 total_invocations() == HeapFirstMaximumCompactionCount;
1396 if (maximum_compaction || full_cp == top_cp || interval_ended) {
1397 _maximum_compaction_gc_num = total_invocations();
1398 return sd.region_to_addr(full_cp);
1399 }
1400
1401 const size_t space_live = pointer_delta(new_top, bottom);
1402 const size_t space_used = space->used_in_words();
1403 const size_t space_capacity = space->capacity_in_words();
1404
1405 const double density = double(space_live) / double(space_capacity);
1406 const size_t min_percent_free =
1407 id == perm_space_id ? PermMarkSweepDeadRatio : MarkSweepDeadRatio;
1408 const double limiter = dead_wood_limiter(density, min_percent_free);
1409 const size_t dead_wood_max = space_used - space_live;
1410 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1411 dead_wood_max);
1412
1413 if (TraceParallelOldGCDensePrefix) {
1414 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1415 "space_cap=" SIZE_FORMAT,
1416 space_live, space_used,
1417 space_capacity);
1418 tty->print_cr("dead_wood_limiter(%6.4f, %d)=%6.4f "
1419 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1420 density, min_percent_free, limiter,
1421 dead_wood_max, dead_wood_limit);
1422 }
1423
1424 // Locate the region with the desired amount of dead space to the left.
1425 const RegionData* const limit_cp =
1426 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1427
1428 // Scan from the first region with dead space to the limit region and find the
1429 // one with the best (largest) reclaimed ratio.
1430 double best_ratio = 0.0;
1431 const RegionData* best_cp = full_cp;
1432 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1433 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1434 if (tmp_ratio > best_ratio) {
1435 best_cp = cp;
1436 best_ratio = tmp_ratio;
1437 }
1438 }
1439
1440 #if 0
1441 // Something to consider: if the region with the best ratio is 'close to' the
1442 // first region w/free space, choose the first region with free space
1443 // ("first-free"). The first-free region is usually near the start of the
1444 // heap, which means we are copying most of the heap already, so copy a bit
1445 // more to get complete compaction.
1446 if (pointer_delta(best_cp, full_cp, sizeof(RegionData)) < 4) {
1447 _maximum_compaction_gc_num = total_invocations();
1448 best_cp = full_cp;
1449 }
1450 #endif // #if 0
1451
1452 return sd.region_to_addr(best_cp);
1453 }
1454
1455 #ifndef PRODUCT
1456 void
1457 PSParallelCompact::fill_with_live_objects(SpaceId id, HeapWord* const start,
1458 size_t words)
1459 {
1460 if (TraceParallelOldGCSummaryPhase) {
1461 tty->print_cr("fill_with_live_objects [" PTR_FORMAT " " PTR_FORMAT ") "
1462 SIZE_FORMAT, start, start + words, words);
1463 }
1464
1465 ObjectStartArray* const start_array = _space_info[id].start_array();
1466 CollectedHeap::fill_with_objects(start, words);
1467 for (HeapWord* p = start; p < start + words; p += oop(p)->size()) {
1468 _mark_bitmap.mark_obj(p, words);
1469 _summary_data.add_obj(p, words);
1470 start_array->allocate_block(p);
1471 }
1472 }
1473
1474 void
1475 PSParallelCompact::summarize_new_objects(SpaceId id, HeapWord* start)
1476 {
1477 ParallelCompactData& sd = summary_data();
1478 MutableSpace* space = _space_info[id].space();
1479
1480 // Find the source and destination start addresses.
1481 HeapWord* const src_addr = sd.region_align_down(start);
1482 HeapWord* dst_addr;
1483 if (src_addr < start) {
1484 dst_addr = sd.addr_to_region_ptr(src_addr)->destination();
1485 } else if (src_addr > space->bottom()) {
1486 // The start (the original top() value) is aligned to a region boundary so
1487 // the associated region does not have a destination. Compute the
1488 // destination from the previous region.
1489 RegionData* const cp = sd.addr_to_region_ptr(src_addr) - 1;
1490 dst_addr = cp->destination() + cp->data_size();
1491 } else {
1492 // Filling the entire space.
1493 dst_addr = space->bottom();
1494 }
1495 assert(dst_addr != NULL, "sanity");
1496
1497 // Update the summary data.
1498 bool result = _summary_data.summarize(_space_info[id].split_info(),
1499 src_addr, space->top(), NULL,
1500 dst_addr, space->end(),
1501 _space_info[id].new_top_addr());
1502 assert(result, "should not fail: bad filler object size");
1503 }
1504
1505 void
1506 PSParallelCompact::provoke_split_fill_survivor(SpaceId id)
1507 {
1508 if (total_invocations() % (ParallelOldGCSplitInterval * 3) != 0) {
1509 return;
1510 }
1511
1512 MutableSpace* const space = _space_info[id].space();
1513 if (space->is_empty()) {
1514 HeapWord* b = space->bottom();
1515 HeapWord* t = b + space->capacity_in_words() / 2;
1516 space->set_top(t);
1517 if (ZapUnusedHeapArea) {
1518 space->set_top_for_allocations();
1519 }
1520
1521 size_t min_size = CollectedHeap::min_fill_size();
1522 size_t obj_len = min_size;
1523 while (b + obj_len <= t) {
1524 CollectedHeap::fill_with_object(b, obj_len);
1525 mark_bitmap()->mark_obj(b, obj_len);
1526 summary_data().add_obj(b, obj_len);
1527 b += obj_len;
1528 obj_len = (obj_len & (min_size*3)) + min_size; // 8 16 24 32 8 16 24 32 ...
1529 }
1530 if (b < t) {
1531 // The loop didn't completely fill to t (top); adjust top downward.
1532 space->set_top(b);
1533 if (ZapUnusedHeapArea) {
1534 space->set_top_for_allocations();
1535 }
1536 }
1537
1538 HeapWord** nta = _space_info[id].new_top_addr();
1539 bool result = summary_data().summarize(_space_info[id].split_info(),
1540 space->bottom(), space->top(), NULL,
1541 space->bottom(), space->end(), nta);
1542 assert(result, "space must fit into itself");
1543 }
1544 }
1545
1546 void
1547 PSParallelCompact::provoke_split(bool & max_compaction)
1548 {
1549 if (total_invocations() % ParallelOldGCSplitInterval != 0) {
1550 return;
1551 }
1552
1553 const size_t region_size = ParallelCompactData::RegionSize;
1554 ParallelCompactData& sd = summary_data();
1555
1556 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1557 MutableSpace* const from_space = _space_info[from_space_id].space();
1558 const size_t eden_live = pointer_delta(eden_space->top(),
1559 _space_info[eden_space_id].new_top());
1560 const size_t from_live = pointer_delta(from_space->top(),
1561 _space_info[from_space_id].new_top());
1562
1563 const size_t min_fill_size = CollectedHeap::min_fill_size();
1564 const size_t eden_free = pointer_delta(eden_space->end(), eden_space->top());
1565 const size_t eden_fillable = eden_free >= min_fill_size ? eden_free : 0;
1566 const size_t from_free = pointer_delta(from_space->end(), from_space->top());
1567 const size_t from_fillable = from_free >= min_fill_size ? from_free : 0;
1568
1569 // Choose the space to split; need at least 2 regions live (or fillable).
1570 SpaceId id;
1571 MutableSpace* space;
1572 size_t live_words;
1573 size_t fill_words;
1574 if (eden_live + eden_fillable >= region_size * 2) {
1575 id = eden_space_id;
1576 space = eden_space;
1577 live_words = eden_live;
1578 fill_words = eden_fillable;
1579 } else if (from_live + from_fillable >= region_size * 2) {
1580 id = from_space_id;
1581 space = from_space;
1582 live_words = from_live;
1583 fill_words = from_fillable;
1584 } else {
1585 return; // Give up.
1586 }
1587 assert(fill_words == 0 || fill_words >= min_fill_size, "sanity");
1588
1589 if (live_words < region_size * 2) {
1590 // Fill from top() to end() w/live objects of mixed sizes.
1591 HeapWord* const fill_start = space->top();
1592 live_words += fill_words;
1593
1594 space->set_top(fill_start + fill_words);
1595 if (ZapUnusedHeapArea) {
1596 space->set_top_for_allocations();
1597 }
1598
1599 HeapWord* cur_addr = fill_start;
1600 while (fill_words > 0) {
1601 const size_t r = (size_t)os::random() % (region_size / 2) + min_fill_size;
1602 size_t cur_size = MIN2(align_object_size_(r), fill_words);
1603 if (fill_words - cur_size < min_fill_size) {
1604 cur_size = fill_words; // Avoid leaving a fragment too small to fill.
1605 }
1606
1607 CollectedHeap::fill_with_object(cur_addr, cur_size);
1608 mark_bitmap()->mark_obj(cur_addr, cur_size);
1609 sd.add_obj(cur_addr, cur_size);
1610
1611 cur_addr += cur_size;
1612 fill_words -= cur_size;
1613 }
1614
1615 summarize_new_objects(id, fill_start);
1616 }
1617
1618 max_compaction = false;
1619
1620 // Manipulate the old gen so that it has room for about half of the live data
1621 // in the target young gen space (live_words / 2).
1622 id = old_space_id;
1623 space = _space_info[id].space();
1624 const size_t free_at_end = space->free_in_words();
1625 const size_t free_target = align_object_size(live_words / 2);
1626 const size_t dead = pointer_delta(space->top(), _space_info[id].new_top());
1627
1628 if (free_at_end >= free_target + min_fill_size) {
1629 // Fill space above top() and set the dense prefix so everything survives.
1630 HeapWord* const fill_start = space->top();
1631 const size_t fill_size = free_at_end - free_target;
1632 space->set_top(space->top() + fill_size);
1633 if (ZapUnusedHeapArea) {
1634 space->set_top_for_allocations();
1635 }
1636 fill_with_live_objects(id, fill_start, fill_size);
1637 summarize_new_objects(id, fill_start);
1638 _space_info[id].set_dense_prefix(sd.region_align_down(space->top()));
1639 } else if (dead + free_at_end > free_target) {
1640 // Find a dense prefix that makes the right amount of space available.
1641 HeapWord* cur = sd.region_align_down(space->top());
1642 HeapWord* cur_destination = sd.addr_to_region_ptr(cur)->destination();
1643 size_t dead_to_right = pointer_delta(space->end(), cur_destination);
1644 while (dead_to_right < free_target) {
1645 cur -= region_size;
1646 cur_destination = sd.addr_to_region_ptr(cur)->destination();
1647 dead_to_right = pointer_delta(space->end(), cur_destination);
1648 }
1649 _space_info[id].set_dense_prefix(cur);
1650 }
1651 }
1652 #endif // #ifndef PRODUCT
1653
1654 void PSParallelCompact::summarize_spaces_quick()
1655 {
1656 for (unsigned int i = 0; i < last_space_id; ++i) {
1657 const MutableSpace* space = _space_info[i].space();
1658 HeapWord** nta = _space_info[i].new_top_addr();
1659 bool result = _summary_data.summarize(_space_info[i].split_info(),
1660 space->bottom(), space->top(), NULL,
1661 space->bottom(), space->end(), nta);
1662 assert(result, "space must fit into itself");
1663 _space_info[i].set_dense_prefix(space->bottom());
1664 }
1665
1666 #ifndef PRODUCT
1667 if (ParallelOldGCSplitALot) {
1668 provoke_split_fill_survivor(to_space_id);
1669 }
1670 #endif // #ifndef PRODUCT
1671 }
1672
1673 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1674 {
1675 HeapWord* const dense_prefix_end = dense_prefix(id);
1676 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1677 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1678 if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1679 // Only enough dead space is filled so that any remaining dead space to the
1680 // left is larger than the minimum filler object. (The remainder is filled
1681 // during the copy/update phase.)
1682 //
1683 // The size of the dead space to the right of the boundary is not a
1684 // concern, since compaction will be able to use whatever space is
1685 // available.
1686 //
1687 // Here '||' is the boundary, 'x' represents a don't care bit and a box
1688 // surrounds the space to be filled with an object.
1689 //
1690 // In the 32-bit VM, each bit represents two 32-bit words:
1691 // +---+
1692 // a) beg_bits: ... x x x | 0 | || 0 x x ...
1693 // end_bits: ... x x x | 0 | || 0 x x ...
1694 // +---+
1695 //
1696 // In the 64-bit VM, each bit represents one 64-bit word:
1697 // +------------+
1698 // b) beg_bits: ... x x x | 0 || 0 | x x ...
1699 // end_bits: ... x x 1 | 0 || 0 | x x ...
1700 // +------------+
1701 // +-------+
1702 // c) beg_bits: ... x x | 0 0 | || 0 x x ...
1703 // end_bits: ... x 1 | 0 0 | || 0 x x ...
1704 // +-------+
1705 // +-----------+
1706 // d) beg_bits: ... x | 0 0 0 | || 0 x x ...
1707 // end_bits: ... 1 | 0 0 0 | || 0 x x ...
1708 // +-----------+
1709 // +-------+
1710 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ...
1711 // end_bits: ... 0 0 | 0 0 | || 0 x x ...
1712 // +-------+
1713
1714 // Initially assume case a, c or e will apply.
1715 size_t obj_len = CollectedHeap::min_fill_size();
1716 HeapWord* obj_beg = dense_prefix_end - obj_len;
1717
1718 #ifdef _LP64
1719 if (MinObjAlignment > 1) { // object alignment > heap word size
1720 // Cases a, c or e.
1721 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1722 // Case b above.
1723 obj_beg = dense_prefix_end - 1;
1724 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1725 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1726 // Case d above.
1727 obj_beg = dense_prefix_end - 3;
1728 obj_len = 3;
1729 }
1730 #endif // #ifdef _LP64
1731
1732 CollectedHeap::fill_with_object(obj_beg, obj_len);
1733 _mark_bitmap.mark_obj(obj_beg, obj_len);
1734 _summary_data.add_obj(obj_beg, obj_len);
1735 assert(start_array(id) != NULL, "sanity");
1736 start_array(id)->allocate_block(obj_beg);
1737 }
1738 }
1739
1740 void
1741 PSParallelCompact::clear_source_region(HeapWord* beg_addr, HeapWord* end_addr)
1742 {
1743 RegionData* const beg_ptr = _summary_data.addr_to_region_ptr(beg_addr);
1744 HeapWord* const end_aligned_up = _summary_data.region_align_up(end_addr);
1745 RegionData* const end_ptr = _summary_data.addr_to_region_ptr(end_aligned_up);
1746 for (RegionData* cur = beg_ptr; cur < end_ptr; ++cur) {
1747 cur->set_source_region(0);
1748 }
1749 }
1750
1751 void
1752 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1753 {
1754 assert(id < last_space_id, "id out of range");
1755 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom() ||
1756 ParallelOldGCSplitALot && id == old_space_id,
1757 "should have been reset in summarize_spaces_quick()");
1758
1759 const MutableSpace* space = _space_info[id].space();
1760 if (_space_info[id].new_top() != space->bottom()) {
1761 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1762 _space_info[id].set_dense_prefix(dense_prefix_end);
1763
1764 #ifndef PRODUCT
1765 if (TraceParallelOldGCDensePrefix) {
1766 print_dense_prefix_stats("ratio", id, maximum_compaction,
1767 dense_prefix_end);
1768 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1769 print_dense_prefix_stats("density", id, maximum_compaction, addr);
1770 }
1771 #endif // #ifndef PRODUCT
1772
1773 // Recompute the summary data, taking into account the dense prefix. If
1774 // every last byte will be reclaimed, then the existing summary data which
1775 // compacts everything can be left in place.
1776 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1777 // If dead space crosses the dense prefix boundary, it is (at least
1778 // partially) filled with a dummy object, marked live and added to the
1779 // summary data. This simplifies the copy/update phase and must be done
1780 // before the final locations of objects are determined, to prevent
1781 // leaving a fragment of dead space that is too small to fill.
1782 fill_dense_prefix_end(id);
1783
1784 // Compute the destination of each Region, and thus each object.
1785 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1786 _summary_data.summarize(_space_info[id].split_info(),
1787 dense_prefix_end, space->top(), NULL,
1788 dense_prefix_end, space->end(),
1789 _space_info[id].new_top_addr());
1790 }
1791 }
1792
1793 if (TraceParallelOldGCSummaryPhase) {
1794 const size_t region_size = ParallelCompactData::RegionSize;
1795 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1796 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1797 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1798 HeapWord* const new_top = _space_info[id].new_top();
1799 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1800 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1801 tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1802 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1803 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1804 id, space->capacity_in_words(), dense_prefix_end,
1805 dp_region, dp_words / region_size,
1806 cr_words / region_size, new_top);
1807 }
1808 }
1809
1810 #ifndef PRODUCT
1811 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1812 HeapWord* dst_beg, HeapWord* dst_end,
1813 SpaceId src_space_id,
1814 HeapWord* src_beg, HeapWord* src_end)
1815 {
1816 if (TraceParallelOldGCSummaryPhase) {
1817 tty->print_cr("summarizing %d [%s] into %d [%s]: "
1818 "src=" PTR_FORMAT "-" PTR_FORMAT " "
1819 SIZE_FORMAT "-" SIZE_FORMAT " "
1820 "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1821 SIZE_FORMAT "-" SIZE_FORMAT,
1822 src_space_id, space_names[src_space_id],
1823 dst_space_id, space_names[dst_space_id],
1824 src_beg, src_end,
1825 _summary_data.addr_to_region_idx(src_beg),
1826 _summary_data.addr_to_region_idx(src_end),
1827 dst_beg, dst_end,
1828 _summary_data.addr_to_region_idx(dst_beg),
1829 _summary_data.addr_to_region_idx(dst_end));
1830 }
1831 }
1832 #endif // #ifndef PRODUCT
1833
1834 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1835 bool maximum_compaction)
1836 {
1837 EventMark m("2 summarize");
1838 TraceTime tm("summary phase", print_phases(), true, gclog_or_tty);
1839 // trace("2");
1840
1841 #ifdef ASSERT
1842 if (TraceParallelOldGCMarkingPhase) {
1843 tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1844 "add_obj_bytes=" SIZE_FORMAT,
1845 add_obj_count, add_obj_size * HeapWordSize);
1846 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1847 "mark_bitmap_bytes=" SIZE_FORMAT,
1848 mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1849 }
1850 #endif // #ifdef ASSERT
1851
1852 // Quick summarization of each space into itself, to see how much is live.
1853 summarize_spaces_quick();
1854
1855 if (TraceParallelOldGCSummaryPhase) {
1856 tty->print_cr("summary_phase: after summarizing each space to self");
1857 Universe::print();
1858 NOT_PRODUCT(print_region_ranges());
1859 if (Verbose) {
1860 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1861 }
1862 }
1863
1864 // The amount of live data that will end up in old space (assuming it fits).
1865 size_t old_space_total_live = 0;
1866 assert(perm_space_id < old_space_id, "should not count perm data here");
1867 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1868 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1869 _space_info[id].space()->bottom());
1870 }
1871
1872 MutableSpace* const old_space = _space_info[old_space_id].space();
1873 const size_t old_capacity = old_space->capacity_in_words();
1874 if (old_space_total_live > old_capacity) {
1875 // XXX - should also try to expand
1876 maximum_compaction = true;
1877 }
1878 #ifndef PRODUCT
1879 if (ParallelOldGCSplitALot && old_space_total_live < old_capacity) {
1880 provoke_split(maximum_compaction);
1881 }
1882 #endif // #ifndef PRODUCT
1883
1884 // Permanent and Old generations.
1885 summarize_space(perm_space_id, maximum_compaction);
1886 summarize_space(old_space_id, maximum_compaction);
1887
1888 // Summarize the remaining spaces in the young gen. The initial target space
1889 // is the old gen. If a space does not fit entirely into the target, then the
1890 // remainder is compacted into the space itself and that space becomes the new
1891 // target.
1892 SpaceId dst_space_id = old_space_id;
1893 HeapWord* dst_space_end = old_space->end();
1894 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1895 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1896 const MutableSpace* space = _space_info[id].space();
1897 const size_t live = pointer_delta(_space_info[id].new_top(),
1898 space->bottom());
1899 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1900
1901 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1902 SpaceId(id), space->bottom(), space->top());)
1903 if (live > 0 && live <= available) {
1904 // All the live data will fit.
1905 bool done = _summary_data.summarize(_space_info[id].split_info(),
1906 space->bottom(), space->top(),
1907 NULL,
1908 *new_top_addr, dst_space_end,
1909 new_top_addr);
1910 assert(done, "space must fit into old gen");
1911
1912 // Reset the new_top value for the space.
1913 _space_info[id].set_new_top(space->bottom());
1914 } else if (live > 0) {
1915 // Attempt to fit part of the source space into the target space.
1916 HeapWord* next_src_addr = NULL;
1917 bool done = _summary_data.summarize(_space_info[id].split_info(),
1918 space->bottom(), space->top(),
1919 &next_src_addr,
1920 *new_top_addr, dst_space_end,
1921 new_top_addr);
1922 assert(!done, "space should not fit into old gen");
1923 assert(next_src_addr != NULL, "sanity");
1924
1925 // The source space becomes the new target, so the remainder is compacted
1926 // within the space itself.
1927 dst_space_id = SpaceId(id);
1928 dst_space_end = space->end();
1929 new_top_addr = _space_info[id].new_top_addr();
1930 NOT_PRODUCT(summary_phase_msg(dst_space_id,
1931 space->bottom(), dst_space_end,
1932 SpaceId(id), next_src_addr, space->top());)
1933 done = _summary_data.summarize(_space_info[id].split_info(),
1934 next_src_addr, space->top(),
1935 NULL,
1936 space->bottom(), dst_space_end,
1937 new_top_addr);
1938 assert(done, "space must fit when compacted into itself");
1939 assert(*new_top_addr <= space->top(), "usage should not grow");
1940 }
1941 }
1942
1943 if (TraceParallelOldGCSummaryPhase) {
1944 tty->print_cr("summary_phase: after final summarization");
1945 Universe::print();
1946 NOT_PRODUCT(print_region_ranges());
1947 if (Verbose) {
1948 NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info));
1949 }
1950 }
1951 }
1952
1953 // This method should contain all heap-specific policy for invoking a full
1954 // collection. invoke_no_policy() will only attempt to compact the heap; it
1955 // will do nothing further. If we need to bail out for policy reasons, scavenge
1956 // before full gc, or any other specialized behavior, it needs to be added here.
1957 //
1958 // Note that this method should only be called from the vm_thread while at a
1959 // safepoint.
1960 //
1961 // Note that the all_soft_refs_clear flag in the collector policy
1962 // may be true because this method can be called without intervening
1963 // activity. For example when the heap space is tight and full measure
1964 // are being taken to free space.
1965 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1966 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1967 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1968 "should be in vm thread");
1969
1970 ParallelScavengeHeap* heap = gc_heap();
1971 GCCause::Cause gc_cause = heap->gc_cause();
1972 assert(!heap->is_gc_active(), "not reentrant");
1973
1974 PSAdaptiveSizePolicy* policy = heap->size_policy();
1975 IsGCActiveMark mark;
1976
1977 if (ScavengeBeforeFullGC) {
1978 PSScavenge::invoke_no_policy();
1979 }
1980
1981 const bool clear_all_soft_refs =
1982 heap->collector_policy()->should_clear_all_soft_refs();
1983
1984 PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1985 maximum_heap_compaction);
1986 }
1987
1988 bool ParallelCompactData::region_contains(size_t region_index, HeapWord* addr) {
1989 size_t addr_region_index = addr_to_region_idx(addr);
1990 return region_index == addr_region_index;
1991 }
1992
1993 // This method contains no policy. You should probably
1994 // be calling invoke() instead.
1995 void PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1996 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1997 assert(ref_processor() != NULL, "Sanity");
1998
1999 if (GC_locker::check_active_before_gc()) {
2000 return;
2001 }
2002
2003 TimeStamp marking_start;
2004 TimeStamp compaction_start;
2005 TimeStamp collection_exit;
2006
2007 ParallelScavengeHeap* heap = gc_heap();
2008 GCCause::Cause gc_cause = heap->gc_cause();
2009 PSYoungGen* young_gen = heap->young_gen();
2010 PSOldGen* old_gen = heap->old_gen();
2011 PSPermGen* perm_gen = heap->perm_gen();
2012 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
2013
2014 // The scope of casr should end after code that can change
2015 // CollectorPolicy::_should_clear_all_soft_refs.
2016 ClearedAllSoftRefs casr(maximum_heap_compaction,
2017 heap->collector_policy());
2018
2019 if (ZapUnusedHeapArea) {
2020 // Save information needed to minimize mangling
2021 heap->record_gen_tops_before_GC();
2022 }
2023
2024 heap->pre_full_gc_dump();
2025
2026 _print_phases = PrintGCDetails && PrintParallelOldGCPhaseTimes;
2027
2028 // Make sure data structures are sane, make the heap parsable, and do other
2029 // miscellaneous bookkeeping.
2030 PreGCValues pre_gc_values;
2031 pre_compact(&pre_gc_values);
2032
2033 // Get the compaction manager reserved for the VM thread.
2034 ParCompactionManager* const vmthread_cm =
2035 ParCompactionManager::manager_array(gc_task_manager()->workers());
2036
2037 // Place after pre_compact() where the number of invocations is incremented.
2038 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
2039
2040 {
2041 ResourceMark rm;
2042 HandleMark hm;
2043
2044 const bool is_system_gc = gc_cause == GCCause::_java_lang_system_gc;
2045
2046 // This is useful for debugging but don't change the output the
2047 // the customer sees.
2048 const char* gc_cause_str = "Full GC";
2049 if (is_system_gc && PrintGCDetails) {
2050 gc_cause_str = "Full GC (System)";
2051 }
2052 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2053 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2054 TraceTime t1(gc_cause_str, PrintGC, !PrintGCDetails, gclog_or_tty);
2055 TraceCollectorStats tcs(counters());
2056 TraceMemoryManagerStats tms(true /* Full GC */);
2057
2058 if (TraceGen1Time) accumulated_time()->start();
2059
2060 // Let the size policy know we're starting
2061 size_policy->major_collection_begin();
2062
2063 // When collecting the permanent generation methodOops may be moving,
2064 // so we either have to flush all bcp data or convert it into bci.
2065 CodeCache::gc_prologue();
2066 Threads::gc_prologue();
2067
2068 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
2069 COMPILER2_PRESENT(DerivedPointerTable::clear());
2070
2071 ref_processor()->enable_discovery();
2072 ref_processor()->setup_policy(maximum_heap_compaction);
2073
2074 bool marked_for_unloading = false;
2075
2076 marking_start.update();
2077 marking_phase(vmthread_cm, maximum_heap_compaction);
2078
2079 #ifndef PRODUCT
2080 if (TraceParallelOldGCMarkingPhase) {
2081 gclog_or_tty->print_cr("marking_phase: cas_tries %d cas_retries %d "
2082 "cas_by_another %d",
2083 mark_bitmap()->cas_tries(), mark_bitmap()->cas_retries(),
2084 mark_bitmap()->cas_by_another());
2085 }
2086 #endif // #ifndef PRODUCT
2087
2088 bool max_on_system_gc = UseMaximumCompactionOnSystemGC && is_system_gc;
2089 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
2090
2091 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
2092 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
2093
2094 // adjust_roots() updates Universe::_intArrayKlassObj which is
2095 // needed by the compaction for filling holes in the dense prefix.
2096 adjust_roots();
2097
2098 compaction_start.update();
2099 // Does the perm gen always have to be done serially because
2100 // klasses are used in the update of an object?
2101 compact_perm(vmthread_cm);
2102
2103 if (UseParallelOldGCCompacting) {
2104 compact();
2105 } else {
2106 compact_serial(vmthread_cm);
2107 }
2108
2109 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
2110 // done before resizing.
2111 post_compact();
2112
2113 // Let the size policy know we're done
2114 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
2115
2116 if (UseAdaptiveSizePolicy) {
2117 if (PrintAdaptiveSizePolicy) {
2118 gclog_or_tty->print("AdaptiveSizeStart: ");
2119 gclog_or_tty->stamp();
2120 gclog_or_tty->print_cr(" collection: %d ",
2121 heap->total_collections());
2122 if (Verbose) {
2123 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d"
2124 " perm_gen_capacity: %d ",
2125 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),
2126 perm_gen->capacity_in_bytes());
2127 }
2128 }
2129
2130 // Don't check if the size_policy is ready here. Let
2131 // the size_policy check that internally.
2132 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
2133 ((gc_cause != GCCause::_java_lang_system_gc) ||
2134 UseAdaptiveSizePolicyWithSystemGC)) {
2135 // Calculate optimal free space amounts
2136 assert(young_gen->max_size() >
2137 young_gen->from_space()->capacity_in_bytes() +
2138 young_gen->to_space()->capacity_in_bytes(),
2139 "Sizes of space in young gen are out-of-bounds");
2140 size_t max_eden_size = young_gen->max_size() -
2141 young_gen->from_space()->capacity_in_bytes() -
2142 young_gen->to_space()->capacity_in_bytes();
2143 size_policy->compute_generation_free_space(
2144 young_gen->used_in_bytes(),
2145 young_gen->eden_space()->used_in_bytes(),
2146 old_gen->used_in_bytes(),
2147 perm_gen->used_in_bytes(),
2148 young_gen->eden_space()->capacity_in_bytes(),
2149 old_gen->max_gen_size(),
2150 max_eden_size,
2151 true /* full gc*/,
2152 gc_cause,
2153 heap->collector_policy());
2154
2155 heap->resize_old_gen(
2156 size_policy->calculated_old_free_size_in_bytes());
2157
2158 // Don't resize the young generation at an major collection. A
2159 // desired young generation size may have been calculated but
2160 // resizing the young generation complicates the code because the
2161 // resizing of the old generation may have moved the boundary
2162 // between the young generation and the old generation. Let the
2163 // young generation resizing happen at the minor collections.
2164 }
2165 if (PrintAdaptiveSizePolicy) {
2166 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
2167 heap->total_collections());
2168 }
2169 }
2170
2171 if (UsePerfData) {
2172 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
2173 counters->update_counters();
2174 counters->update_old_capacity(old_gen->capacity_in_bytes());
2175 counters->update_young_capacity(young_gen->capacity_in_bytes());
2176 }
2177
2178 heap->resize_all_tlabs();
2179
2180 // We collected the perm gen, so we'll resize it here.
2181 perm_gen->compute_new_size(pre_gc_values.perm_gen_used());
2182
2183 if (TraceGen1Time) accumulated_time()->stop();
2184
2185 if (PrintGC) {
2186 if (PrintGCDetails) {
2187 // No GC timestamp here. This is after GC so it would be confusing.
2188 young_gen->print_used_change(pre_gc_values.young_gen_used());
2189 old_gen->print_used_change(pre_gc_values.old_gen_used());
2190 heap->print_heap_change(pre_gc_values.heap_used());
2191 // Print perm gen last (print_heap_change() excludes the perm gen).
2192 perm_gen->print_used_change(pre_gc_values.perm_gen_used());
2193 } else {
2194 heap->print_heap_change(pre_gc_values.heap_used());
2195 }
2196 }
2197
2198 // Track memory usage and detect low memory
2199 MemoryService::track_memory_usage();
2200 heap->update_counters();
2201 }
2202
2203 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
2204 HandleMark hm; // Discard invalid handles created during verification
2205 gclog_or_tty->print(" VerifyAfterGC:");
2206 Universe::verify(false);
2207 }
2208
2209 // Re-verify object start arrays
2210 if (VerifyObjectStartArray &&
2211 VerifyAfterGC) {
2212 old_gen->verify_object_start_array();
2213 perm_gen->verify_object_start_array();
2214 }
2215
2216 if (ZapUnusedHeapArea) {
2217 old_gen->object_space()->check_mangled_unused_area_complete();
2218 perm_gen->object_space()->check_mangled_unused_area_complete();
2219 }
2220
2221 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
2222
2223 collection_exit.update();
2224
2225 if (PrintHeapAtGC) {
2226 Universe::print_heap_after_gc();
2227 }
2228 if (PrintGCTaskTimeStamps) {
2229 gclog_or_tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " "
2230 INT64_FORMAT,
2231 marking_start.ticks(), compaction_start.ticks(),
2232 collection_exit.ticks());
2233 gc_task_manager()->print_task_time_stamps();
2234 }
2235
2236 heap->post_full_gc_dump();
2237
2238 #ifdef TRACESPINNING
2239 ParallelTaskTerminator::print_termination_counts();
2240 #endif
2241 }
2242
2243 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
2244 PSYoungGen* young_gen,
2245 PSOldGen* old_gen) {
2246 MutableSpace* const eden_space = young_gen->eden_space();
2247 assert(!eden_space->is_empty(), "eden must be non-empty");
2248 assert(young_gen->virtual_space()->alignment() ==
2249 old_gen->virtual_space()->alignment(), "alignments do not match");
2250
2251 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
2252 return false;
2253 }
2254
2255 // Both generations must be completely committed.
2256 if (young_gen->virtual_space()->uncommitted_size() != 0) {
2257 return false;
2258 }
2259 if (old_gen->virtual_space()->uncommitted_size() != 0) {
2260 return false;
2261 }
2262
2263 // Figure out how much to take from eden. Include the average amount promoted
2264 // in the total; otherwise the next young gen GC will simply bail out to a
2265 // full GC.
2266 const size_t alignment = old_gen->virtual_space()->alignment();
2267 const size_t eden_used = eden_space->used_in_bytes();
2268 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
2269 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
2270 const size_t eden_capacity = eden_space->capacity_in_bytes();
2271
2272 if (absorb_size >= eden_capacity) {
2273 return false; // Must leave some space in eden.
2274 }
2275
2276 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2277 if (new_young_size < young_gen->min_gen_size()) {
2278 return false; // Respect young gen minimum size.
2279 }
2280
2281 if (TraceAdaptiveGCBoundary && Verbose) {
2282 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
2283 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2284 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2285 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2286 absorb_size / K,
2287 eden_capacity / K, (eden_capacity - absorb_size) / K,
2288 young_gen->from_space()->used_in_bytes() / K,
2289 young_gen->to_space()->used_in_bytes() / K,
2290 young_gen->capacity_in_bytes() / K, new_young_size / K);
2291 }
2292
2293 // Fill the unused part of the old gen.
2294 MutableSpace* const old_space = old_gen->object_space();
2295 HeapWord* const unused_start = old_space->top();
2296 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2297
2298 if (unused_words > 0) {
2299 if (unused_words < CollectedHeap::min_fill_size()) {
2300 return false; // If the old gen cannot be filled, must give up.
2301 }
2302 CollectedHeap::fill_with_objects(unused_start, unused_words);
2303 }
2304
2305 // Take the live data from eden and set both top and end in the old gen to
2306 // eden top. (Need to set end because reset_after_change() mangles the region
2307 // from end to virtual_space->high() in debug builds).
2308 HeapWord* const new_top = eden_space->top();
2309 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2310 absorb_size);
2311 young_gen->reset_after_change();
2312 old_space->set_top(new_top);
2313 old_space->set_end(new_top);
2314 old_gen->reset_after_change();
2315
2316 // Update the object start array for the filler object and the data from eden.
2317 ObjectStartArray* const start_array = old_gen->start_array();
2318 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2319 start_array->allocate_block(p);
2320 }
2321
2322 // Could update the promoted average here, but it is not typically updated at
2323 // full GCs and the value to use is unclear. Something like
2324 //
2325 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2326
2327 size_policy->set_bytes_absorbed_from_eden(absorb_size);
2328 return true;
2329 }
2330
2331 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2332 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2333 "shouldn't return NULL");
2334 return ParallelScavengeHeap::gc_task_manager();
2335 }
2336
2337 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2338 bool maximum_heap_compaction) {
2339 // Recursively traverse all live objects and mark them
2340 EventMark m("1 mark object");
2341 TraceTime tm("marking phase", print_phases(), true, gclog_or_tty);
2342
2343 ParallelScavengeHeap* heap = gc_heap();
2344 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2345 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2346 ParallelTaskTerminator terminator(parallel_gc_threads, qset);
2347
2348 PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
2349 PSParallelCompact::FollowStackClosure follow_stack_closure(cm);
2350
2351 {
2352 TraceTime tm_m("par mark", print_phases(), true, gclog_or_tty);
2353 ParallelScavengeHeap::ParStrongRootsScope psrs;
2354
2355 GCTaskQueue* q = GCTaskQueue::create();
2356
2357 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2358 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2359 // We scan the thread roots in parallel
2360 Threads::create_thread_roots_marking_tasks(q);
2361 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2362 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
2363 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2364 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2365 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2366 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::vm_symbols));
2367 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2368
2369 if (parallel_gc_threads > 1) {
2370 for (uint j = 0; j < parallel_gc_threads; j++) {
2371 q->enqueue(new StealMarkingTask(&terminator));
2372 }
2373 }
2374
2375 WaitForBarrierGCTask* fin = WaitForBarrierGCTask::create();
2376 q->enqueue(fin);
2377
2378 gc_task_manager()->add_list(q);
2379
2380 fin->wait_for();
2381
2382 // We have to release the barrier tasks!
2383 WaitForBarrierGCTask::destroy(fin);
2384 }
2385
2386 // Process reference objects found during marking
2387 {
2388 TraceTime tm_r("reference processing", print_phases(), true, gclog_or_tty);
2389 if (ref_processor()->processing_is_mt()) {
2390 RefProcTaskExecutor task_executor;
2391 ref_processor()->process_discovered_references(
2392 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2393 &task_executor);
2394 } else {
2395 ref_processor()->process_discovered_references(
2396 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL);
2397 }
2398 }
2399
2400 TraceTime tm_c("class unloading", print_phases(), true, gclog_or_tty);
2401 // Follow system dictionary roots and unload classes.
2402 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
2403
2404 // Follow code cache roots.
2405 CodeCache::do_unloading(is_alive_closure(), &mark_and_push_closure,
2406 purged_class);
2407 cm->follow_marking_stacks(); // Flush marking stack.
2408
2409 // Update subklass/sibling/implementor links of live klasses
2410 // revisit_klass_stack is used in follow_weak_klass_links().
2411 follow_weak_klass_links();
2412
2413 // Revisit memoized MDO's and clear any unmarked weak refs
2414 follow_mdo_weak_refs();
2415
2416 // Visit symbol and interned string tables and delete unmarked oops
2417 SymbolTable::unlink(is_alive_closure());
2418 StringTable::unlink(is_alive_closure());
2419
2420 assert(cm->marking_stacks_empty(), "marking stacks should be empty");
2421 }
2422
2423 // This should be moved to the shared markSweep code!
2424 class PSAlwaysTrueClosure: public BoolObjectClosure {
2425 public:
2426 void do_object(oop p) { ShouldNotReachHere(); }
2427 bool do_object_b(oop p) { return true; }
2428 };
2429 static PSAlwaysTrueClosure always_true;
2430
2431 void PSParallelCompact::adjust_roots() {
2432 // Adjust the pointers to reflect the new locations
2433 EventMark m("3 adjust roots");
2434 TraceTime tm("adjust roots", print_phases(), true, gclog_or_tty);
2435
2436 // General strong roots.
2437 Universe::oops_do(adjust_root_pointer_closure());
2438 ReferenceProcessor::oops_do(adjust_root_pointer_closure());
2439 JNIHandles::oops_do(adjust_root_pointer_closure()); // Global (strong) JNI handles
2440 Threads::oops_do(adjust_root_pointer_closure(), NULL);
2441 ObjectSynchronizer::oops_do(adjust_root_pointer_closure());
2442 FlatProfiler::oops_do(adjust_root_pointer_closure());
2443 Management::oops_do(adjust_root_pointer_closure());
2444 JvmtiExport::oops_do(adjust_root_pointer_closure());
2445 // SO_AllClasses
2446 SystemDictionary::oops_do(adjust_root_pointer_closure());
2447 vmSymbols::oops_do(adjust_root_pointer_closure());
2448
2449 // Now adjust pointers in remaining weak roots. (All of which should
2450 // have been cleared if they pointed to non-surviving objects.)
2451 // Global (weak) JNI handles
2452 JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure());
2453
2454 CodeCache::oops_do(adjust_pointer_closure());
2455 SymbolTable::oops_do(adjust_root_pointer_closure());
2456 StringTable::oops_do(adjust_root_pointer_closure());
2457 ref_processor()->weak_oops_do(adjust_root_pointer_closure());
2458 // Roots were visited so references into the young gen in roots
2459 // may have been scanned. Process them also.
2460 // Should the reference processor have a span that excludes
2461 // young gen objects?
2462 PSScavenge::reference_processor()->weak_oops_do(
2463 adjust_root_pointer_closure());
2464 }
2465
2466 void PSParallelCompact::compact_perm(ParCompactionManager* cm) {
2467 EventMark m("4 compact perm");
2468 TraceTime tm("compact perm gen", print_phases(), true, gclog_or_tty);
2469 // trace("4");
2470
2471 gc_heap()->perm_gen()->start_array()->reset();
2472 move_and_update(cm, perm_space_id);
2473 }
2474
2475 void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q,
2476 uint parallel_gc_threads)
2477 {
2478 TraceTime tm("drain task setup", print_phases(), true, gclog_or_tty);
2479
2480 const unsigned int task_count = MAX2(parallel_gc_threads, 1U);
2481 for (unsigned int j = 0; j < task_count; j++) {
2482 q->enqueue(new DrainStacksCompactionTask());
2483 }
2484
2485 // Find all regions that are available (can be filled immediately) and
2486 // distribute them to the thread stacks. The iteration is done in reverse
2487 // order (high to low) so the regions will be removed in ascending order.
2488
2489 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2490
2491 size_t fillable_regions = 0; // A count for diagnostic purposes.
2492 unsigned int which = 0; // The worker thread number.
2493
2494 for (unsigned int id = to_space_id; id > perm_space_id; --id) {
2495 SpaceInfo* const space_info = _space_info + id;
2496 MutableSpace* const space = space_info->space();
2497 HeapWord* const new_top = space_info->new_top();
2498
2499 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2500 const size_t end_region =
2501 sd.addr_to_region_idx(sd.region_align_up(new_top));
2502 assert(end_region > 0, "perm gen cannot be empty");
2503
2504 for (size_t cur = end_region - 1; cur >= beg_region; --cur) {
2505 if (sd.region(cur)->claim_unsafe()) {
2506 ParCompactionManager* cm = ParCompactionManager::manager_array(which);
2507 cm->push_region(cur);
2508
2509 if (TraceParallelOldGCCompactionPhase && Verbose) {
2510 const size_t count_mod_8 = fillable_regions & 7;
2511 if (count_mod_8 == 0) gclog_or_tty->print("fillable: ");
2512 gclog_or_tty->print(" " SIZE_FORMAT_W(7), cur);
2513 if (count_mod_8 == 7) gclog_or_tty->cr();
2514 }
2515
2516 NOT_PRODUCT(++fillable_regions;)
2517
2518 // Assign regions to threads in round-robin fashion.
2519 if (++which == task_count) {
2520 which = 0;
2521 }
2522 }
2523 }
2524 }
2525
2526 if (TraceParallelOldGCCompactionPhase) {
2527 if (Verbose && (fillable_regions & 7) != 0) gclog_or_tty->cr();
2528 gclog_or_tty->print_cr("%u initially fillable regions", fillable_regions);
2529 }
2530 }
2531
2532 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2533
2534 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2535 uint parallel_gc_threads) {
2536 TraceTime tm("dense prefix task setup", print_phases(), true, gclog_or_tty);
2537
2538 ParallelCompactData& sd = PSParallelCompact::summary_data();
2539
2540 // Iterate over all the spaces adding tasks for updating
2541 // regions in the dense prefix. Assume that 1 gc thread
2542 // will work on opening the gaps and the remaining gc threads
2543 // will work on the dense prefix.
2544 unsigned int space_id;
2545 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2546 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2547 const MutableSpace* const space = _space_info[space_id].space();
2548
2549 if (dense_prefix_end == space->bottom()) {
2550 // There is no dense prefix for this space.
2551 continue;
2552 }
2553
2554 // The dense prefix is before this region.
2555 size_t region_index_end_dense_prefix =
2556 sd.addr_to_region_idx(dense_prefix_end);
2557 RegionData* const dense_prefix_cp =
2558 sd.region(region_index_end_dense_prefix);
2559 assert(dense_prefix_end == space->end() ||
2560 dense_prefix_cp->available() ||
2561 dense_prefix_cp->claimed(),
2562 "The region after the dense prefix should always be ready to fill");
2563
2564 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2565
2566 // Is there dense prefix work?
2567 size_t total_dense_prefix_regions =
2568 region_index_end_dense_prefix - region_index_start;
2569 // How many regions of the dense prefix should be given to
2570 // each thread?
2571 if (total_dense_prefix_regions > 0) {
2572 uint tasks_for_dense_prefix = 1;
2573 if (UseParallelDensePrefixUpdate) {
2574 if (total_dense_prefix_regions <=
2575 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2576 // Don't over partition. This assumes that
2577 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2578 // so there are not many regions to process.
2579 tasks_for_dense_prefix = parallel_gc_threads;
2580 } else {
2581 // Over partition
2582 tasks_for_dense_prefix = parallel_gc_threads *
2583 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2584 }
2585 }
2586 size_t regions_per_thread = total_dense_prefix_regions /
2587 tasks_for_dense_prefix;
2588 // Give each thread at least 1 region.
2589 if (regions_per_thread == 0) {
2590 regions_per_thread = 1;
2591 }
2592
2593 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2594 if (region_index_start >= region_index_end_dense_prefix) {
2595 break;
2596 }
2597 // region_index_end is not processed
2598 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2599 region_index_end_dense_prefix);
2600 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2601 region_index_start,
2602 region_index_end));
2603 region_index_start = region_index_end;
2604 }
2605 }
2606 // This gets any part of the dense prefix that did not
2607 // fit evenly.
2608 if (region_index_start < region_index_end_dense_prefix) {
2609 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2610 region_index_start,
2611 region_index_end_dense_prefix));
2612 }
2613 }
2614 }
2615
2616 void PSParallelCompact::enqueue_region_stealing_tasks(
2617 GCTaskQueue* q,
2618 ParallelTaskTerminator* terminator_ptr,
2619 uint parallel_gc_threads) {
2620 TraceTime tm("steal task setup", print_phases(), true, gclog_or_tty);
2621
2622 // Once a thread has drained it's stack, it should try to steal regions from
2623 // other threads.
2624 if (parallel_gc_threads > 1) {
2625 for (uint j = 0; j < parallel_gc_threads; j++) {
2626 q->enqueue(new StealRegionCompactionTask(terminator_ptr));
2627 }
2628 }
2629 }
2630
2631 void PSParallelCompact::compact() {
2632 EventMark m("5 compact");
2633 // trace("5");
2634 TraceTime tm("compaction phase", print_phases(), true, gclog_or_tty);
2635
2636 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
2637 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
2638 PSOldGen* old_gen = heap->old_gen();
2639 old_gen->start_array()->reset();
2640 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2641 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2642 ParallelTaskTerminator terminator(parallel_gc_threads, qset);
2643
2644 GCTaskQueue* q = GCTaskQueue::create();
2645 enqueue_region_draining_tasks(q, parallel_gc_threads);
2646 enqueue_dense_prefix_tasks(q, parallel_gc_threads);
2647 enqueue_region_stealing_tasks(q, &terminator, parallel_gc_threads);
2648
2649 {
2650 TraceTime tm_pc("par compact", print_phases(), true, gclog_or_tty);
2651
2652 WaitForBarrierGCTask* fin = WaitForBarrierGCTask::create();
2653 q->enqueue(fin);
2654
2655 gc_task_manager()->add_list(q);
2656
2657 fin->wait_for();
2658
2659 // We have to release the barrier tasks!
2660 WaitForBarrierGCTask::destroy(fin);
2661
2662 #ifdef ASSERT
2663 // Verify that all regions have been processed before the deferred updates.
2664 // Note that perm_space_id is skipped; this type of verification is not
2665 // valid until the perm gen is compacted by regions.
2666 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2667 verify_complete(SpaceId(id));
2668 }
2669 #endif
2670 }
2671
2672 {
2673 // Update the deferred objects, if any. Any compaction manager can be used.
2674 TraceTime tm_du("deferred updates", print_phases(), true, gclog_or_tty);
2675 ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2676 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2677 update_deferred_objects(cm, SpaceId(id));
2678 }
2679 }
2680 }
2681
2682 #ifdef ASSERT
2683 void PSParallelCompact::verify_complete(SpaceId space_id) {
2684 // All Regions between space bottom() to new_top() should be marked as filled
2685 // and all Regions between new_top() and top() should be available (i.e.,
2686 // should have been emptied).
2687 ParallelCompactData& sd = summary_data();
2688 SpaceInfo si = _space_info[space_id];
2689 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2690 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2691 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2692 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2693 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2694
2695 bool issued_a_warning = false;
2696
2697 size_t cur_region;
2698 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2699 const RegionData* const c = sd.region(cur_region);
2700 if (!c->completed()) {
2701 warning("region " SIZE_FORMAT " not filled: "
2702 "destination_count=" SIZE_FORMAT,
2703 cur_region, c->destination_count());
2704 issued_a_warning = true;
2705 }
2706 }
2707
2708 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2709 const RegionData* const c = sd.region(cur_region);
2710 if (!c->available()) {
2711 warning("region " SIZE_FORMAT " not empty: "
2712 "destination_count=" SIZE_FORMAT,
2713 cur_region, c->destination_count());
2714 issued_a_warning = true;
2715 }
2716 }
2717
2718 if (issued_a_warning) {
2719 print_region_ranges();
2720 }
2721 }
2722 #endif // #ifdef ASSERT
2723
2724 void PSParallelCompact::compact_serial(ParCompactionManager* cm) {
2725 EventMark m("5 compact serial");
2726 TraceTime tm("compact serial", print_phases(), true, gclog_or_tty);
2727
2728 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
2729 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
2730
2731 PSYoungGen* young_gen = heap->young_gen();
2732 PSOldGen* old_gen = heap->old_gen();
2733
2734 old_gen->start_array()->reset();
2735 old_gen->move_and_update(cm);
2736 young_gen->move_and_update(cm);
2737 }
2738
2739 void
2740 PSParallelCompact::follow_weak_klass_links() {
2741 // All klasses on the revisit stack are marked at this point.
2742 // Update and follow all subklass, sibling and implementor links.
2743 if (PrintRevisitStats) {
2744 gclog_or_tty->print_cr("#classes in system dictionary = %d", SystemDictionary::number_of_classes());
2745 }
2746 for (uint i = 0; i < ParallelGCThreads + 1; i++) {
2747 ParCompactionManager* cm = ParCompactionManager::manager_array(i);
2748 KeepAliveClosure keep_alive_closure(cm);
2749 int length = cm->revisit_klass_stack()->length();
2750 if (PrintRevisitStats) {
2751 gclog_or_tty->print_cr("Revisit klass stack[%d] length = %d", i, length);
2752 }
2753 for (int j = 0; j < length; j++) {
2754 cm->revisit_klass_stack()->at(j)->follow_weak_klass_links(
2755 is_alive_closure(),
2756 &keep_alive_closure);
2757 }
2758 // revisit_klass_stack is cleared in reset()
2759 cm->follow_marking_stacks();
2760 }
2761 }
2762
2763 void
2764 PSParallelCompact::revisit_weak_klass_link(ParCompactionManager* cm, Klass* k) {
2765 cm->revisit_klass_stack()->push(k);
2766 }
2767
2768 void PSParallelCompact::revisit_mdo(ParCompactionManager* cm, DataLayout* p) {
2769 cm->revisit_mdo_stack()->push(p);
2770 }
2771
2772 void PSParallelCompact::follow_mdo_weak_refs() {
2773 // All strongly reachable oops have been marked at this point;
2774 // we can visit and clear any weak references from MDO's which
2775 // we memoized during the strong marking phase.
2776 if (PrintRevisitStats) {
2777 gclog_or_tty->print_cr("#classes in system dictionary = %d", SystemDictionary::number_of_classes());
2778 }
2779 for (uint i = 0; i < ParallelGCThreads + 1; i++) {
2780 ParCompactionManager* cm = ParCompactionManager::manager_array(i);
2781 GrowableArray<DataLayout*>* rms = cm->revisit_mdo_stack();
2782 int length = rms->length();
2783 if (PrintRevisitStats) {
2784 gclog_or_tty->print_cr("Revisit MDO stack[%d] length = %d", i, length);
2785 }
2786 for (int j = 0; j < length; j++) {
2787 rms->at(j)->follow_weak_refs(is_alive_closure());
2788 }
2789 // revisit_mdo_stack is cleared in reset()
2790 cm->follow_marking_stacks();
2791 }
2792 }
2793
2794
2795 #ifdef VALIDATE_MARK_SWEEP
2796
2797 void PSParallelCompact::track_adjusted_pointer(void* p, bool isroot) {
2798 if (!ValidateMarkSweep)
2799 return;
2800
2801 if (!isroot) {
2802 if (_pointer_tracking) {
2803 guarantee(_adjusted_pointers->contains(p), "should have seen this pointer");
2804 _adjusted_pointers->remove(p);
2805 }
2806 } else {
2807 ptrdiff_t index = _root_refs_stack->find(p);
2808 if (index != -1) {
2809 int l = _root_refs_stack->length();
2810 if (l > 0 && l - 1 != index) {
2811 void* last = _root_refs_stack->pop();
2812 assert(last != p, "should be different");
2813 _root_refs_stack->at_put(index, last);
2814 } else {
2815 _root_refs_stack->remove(p);
2816 }
2817 }
2818 }
2819 }
2820
2821
2822 void PSParallelCompact::check_adjust_pointer(void* p) {
2823 _adjusted_pointers->push(p);
2824 }
2825
2826
2827 class AdjusterTracker: public OopClosure {
2828 public:
2829 AdjusterTracker() {};
2830 void do_oop(oop* o) { PSParallelCompact::check_adjust_pointer(o); }
2831 void do_oop(narrowOop* o) { PSParallelCompact::check_adjust_pointer(o); }
2832 };
2833
2834
2835 void PSParallelCompact::track_interior_pointers(oop obj) {
2836 if (ValidateMarkSweep) {
2837 _adjusted_pointers->clear();
2838 _pointer_tracking = true;
2839
2840 AdjusterTracker checker;
2841 obj->oop_iterate(&checker);
2842 }
2843 }
2844
2845
2846 void PSParallelCompact::check_interior_pointers() {
2847 if (ValidateMarkSweep) {
2848 _pointer_tracking = false;
2849 guarantee(_adjusted_pointers->length() == 0, "should have processed the same pointers");
2850 }
2851 }
2852
2853
2854 void PSParallelCompact::reset_live_oop_tracking(bool at_perm) {
2855 if (ValidateMarkSweep) {
2856 guarantee((size_t)_live_oops->length() == _live_oops_index, "should be at end of live oops");
2857 _live_oops_index = at_perm ? _live_oops_index_at_perm : 0;
2858 }
2859 }
2860
2861
2862 void PSParallelCompact::register_live_oop(oop p, size_t size) {
2863 if (ValidateMarkSweep) {
2864 _live_oops->push(p);
2865 _live_oops_size->push(size);
2866 _live_oops_index++;
2867 }
2868 }
2869
2870 void PSParallelCompact::validate_live_oop(oop p, size_t size) {
2871 if (ValidateMarkSweep) {
2872 oop obj = _live_oops->at((int)_live_oops_index);
2873 guarantee(obj == p, "should be the same object");
2874 guarantee(_live_oops_size->at((int)_live_oops_index) == size, "should be the same size");
2875 _live_oops_index++;
2876 }
2877 }
2878
2879 void PSParallelCompact::live_oop_moved_to(HeapWord* q, size_t size,
2880 HeapWord* compaction_top) {
2881 assert(oop(q)->forwardee() == NULL || oop(q)->forwardee() == oop(compaction_top),
2882 "should be moved to forwarded location");
2883 if (ValidateMarkSweep) {
2884 PSParallelCompact::validate_live_oop(oop(q), size);
2885 _live_oops_moved_to->push(oop(compaction_top));
2886 }
2887 if (RecordMarkSweepCompaction) {
2888 _cur_gc_live_oops->push(q);
2889 _cur_gc_live_oops_moved_to->push(compaction_top);
2890 _cur_gc_live_oops_size->push(size);
2891 }
2892 }
2893
2894
2895 void PSParallelCompact::compaction_complete() {
2896 if (RecordMarkSweepCompaction) {
2897 GrowableArray<HeapWord*>* _tmp_live_oops = _cur_gc_live_oops;
2898 GrowableArray<HeapWord*>* _tmp_live_oops_moved_to = _cur_gc_live_oops_moved_to;
2899 GrowableArray<size_t> * _tmp_live_oops_size = _cur_gc_live_oops_size;
2900
2901 _cur_gc_live_oops = _last_gc_live_oops;
2902 _cur_gc_live_oops_moved_to = _last_gc_live_oops_moved_to;
2903 _cur_gc_live_oops_size = _last_gc_live_oops_size;
2904 _last_gc_live_oops = _tmp_live_oops;
2905 _last_gc_live_oops_moved_to = _tmp_live_oops_moved_to;
2906 _last_gc_live_oops_size = _tmp_live_oops_size;
2907 }
2908 }
2909
2910
2911 void PSParallelCompact::print_new_location_of_heap_address(HeapWord* q) {
2912 if (!RecordMarkSweepCompaction) {
2913 tty->print_cr("Requires RecordMarkSweepCompaction to be enabled");
2914 return;
2915 }
2916
2917 if (_last_gc_live_oops == NULL) {
2918 tty->print_cr("No compaction information gathered yet");
2919 return;
2920 }
2921
2922 for (int i = 0; i < _last_gc_live_oops->length(); i++) {
2923 HeapWord* old_oop = _last_gc_live_oops->at(i);
2924 size_t sz = _last_gc_live_oops_size->at(i);
2925 if (old_oop <= q && q < (old_oop + sz)) {
2926 HeapWord* new_oop = _last_gc_live_oops_moved_to->at(i);
2927 size_t offset = (q - old_oop);
2928 tty->print_cr("Address " PTR_FORMAT, q);
2929 tty->print_cr(" Was in oop " PTR_FORMAT ", size %d, at offset %d", old_oop, sz, offset);
2930 tty->print_cr(" Now in oop " PTR_FORMAT ", actual address " PTR_FORMAT, new_oop, new_oop + offset);
2931 return;
2932 }
2933 }
2934
2935 tty->print_cr("Address " PTR_FORMAT " not found in live oop information from last GC", q);
2936 }
2937 #endif //VALIDATE_MARK_SWEEP
2938
2939 // Update interior oops in the ranges of regions [beg_region, end_region).
2940 void
2941 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2942 SpaceId space_id,
2943 size_t beg_region,
2944 size_t end_region) {
2945 ParallelCompactData& sd = summary_data();
2946 ParMarkBitMap* const mbm = mark_bitmap();
2947
2948 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2949 HeapWord* const end_addr = sd.region_to_addr(end_region);
2950 assert(beg_region <= end_region, "bad region range");
2951 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2952
2953 #ifdef ASSERT
2954 // Claim the regions to avoid triggering an assert when they are marked as
2955 // filled.
2956 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2957 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2958 }
2959 #endif // #ifdef ASSERT
2960
2961 if (beg_addr != space(space_id)->bottom()) {
2962 // Find the first live object or block of dead space that *starts* in this
2963 // range of regions. If a partial object crosses onto the region, skip it;
2964 // it will be marked for 'deferred update' when the object head is
2965 // processed. If dead space crosses onto the region, it is also skipped; it
2966 // will be filled when the prior region is processed. If neither of those
2967 // apply, the first word in the region is the start of a live object or dead
2968 // space.
2969 assert(beg_addr > space(space_id)->bottom(), "sanity");
2970 const RegionData* const cp = sd.region(beg_region);
2971 if (cp->partial_obj_size() != 0) {
2972 beg_addr = sd.partial_obj_end(beg_region);
2973 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2974 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2975 }
2976 }
2977
2978 if (beg_addr < end_addr) {
2979 // A live object or block of dead space starts in this range of Regions.
2980 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2981
2982 // Create closures and iterate.
2983 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2984 FillClosure fill_closure(cm, space_id);
2985 ParMarkBitMap::IterationStatus status;
2986 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2987 dense_prefix_end);
2988 if (status == ParMarkBitMap::incomplete) {
2989 update_closure.do_addr(update_closure.source());
2990 }
2991 }
2992
2993 // Mark the regions as filled.
2994 RegionData* const beg_cp = sd.region(beg_region);
2995 RegionData* const end_cp = sd.region(end_region);
2996 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2997 cp->set_completed();
2998 }
2999 }
3000
3001 // Return the SpaceId for the space containing addr. If addr is not in the
3002 // heap, last_space_id is returned. In debug mode it expects the address to be
3003 // in the heap and asserts such.
3004 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
3005 assert(Universe::heap()->is_in_reserved(addr), "addr not in the heap");
3006
3007 for (unsigned int id = perm_space_id; id < last_space_id; ++id) {
3008 if (_space_info[id].space()->contains(addr)) {
3009 return SpaceId(id);
3010 }
3011 }
3012
3013 assert(false, "no space contains the addr");
3014 return last_space_id;
3015 }
3016
3017 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
3018 SpaceId id) {
3019 assert(id < last_space_id, "bad space id");
3020
3021 ParallelCompactData& sd = summary_data();
3022 const SpaceInfo* const space_info = _space_info + id;
3023 ObjectStartArray* const start_array = space_info->start_array();
3024
3025 const MutableSpace* const space = space_info->space();
3026 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
3027 HeapWord* const beg_addr = space_info->dense_prefix();
3028 HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
3029
3030 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
3031 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
3032 const RegionData* cur_region;
3033 for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
3034 HeapWord* const addr = cur_region->deferred_obj_addr();
3035 if (addr != NULL) {
3036 if (start_array != NULL) {
3037 start_array->allocate_block(addr);
3038 }
3039 oop(addr)->update_contents(cm);
3040 assert(oop(addr)->is_oop_or_null(), "should be an oop now");
3041 }
3042 }
3043 }
3044
3045 // Skip over count live words starting from beg, and return the address of the
3046 // next live word. Unless marked, the word corresponding to beg is assumed to
3047 // be dead. Callers must either ensure beg does not correspond to the middle of
3048 // an object, or account for those live words in some other way. Callers must
3049 // also ensure that there are enough live words in the range [beg, end) to skip.
3050 HeapWord*
3051 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
3052 {
3053 assert(count > 0, "sanity");
3054
3055 ParMarkBitMap* m = mark_bitmap();
3056 idx_t bits_to_skip = m->words_to_bits(count);
3057 idx_t cur_beg = m->addr_to_bit(beg);
3058 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
3059
3060 do {
3061 cur_beg = m->find_obj_beg(cur_beg, search_end);
3062 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
3063 const size_t obj_bits = cur_end - cur_beg + 1;
3064 if (obj_bits > bits_to_skip) {
3065 return m->bit_to_addr(cur_beg + bits_to_skip);
3066 }
3067 bits_to_skip -= obj_bits;
3068 cur_beg = cur_end + 1;
3069 } while (bits_to_skip > 0);
3070
3071 // Skipping the desired number of words landed just past the end of an object.
3072 // Find the start of the next object.
3073 cur_beg = m->find_obj_beg(cur_beg, search_end);
3074 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
3075 return m->bit_to_addr(cur_beg);
3076 }
3077
3078 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
3079 SpaceId src_space_id,
3080 size_t src_region_idx)
3081 {
3082 assert(summary_data().is_region_aligned(dest_addr), "not aligned");
3083
3084 const SplitInfo& split_info = _space_info[src_space_id].split_info();
3085 if (split_info.dest_region_addr() == dest_addr) {
3086 // The partial object ending at the split point contains the first word to
3087 // be copied to dest_addr.
3088 return split_info.first_src_addr();
3089 }
3090
3091 const ParallelCompactData& sd = summary_data();
3092 ParMarkBitMap* const bitmap = mark_bitmap();
3093 const size_t RegionSize = ParallelCompactData::RegionSize;
3094
3095 assert(sd.is_region_aligned(dest_addr), "not aligned");
3096 const RegionData* const src_region_ptr = sd.region(src_region_idx);
3097 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
3098 HeapWord* const src_region_destination = src_region_ptr->destination();
3099
3100 assert(dest_addr >= src_region_destination, "wrong src region");
3101 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
3102
3103 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
3104 HeapWord* const src_region_end = src_region_beg + RegionSize;
3105
3106 HeapWord* addr = src_region_beg;
3107 if (dest_addr == src_region_destination) {
3108 // Return the first live word in the source region.
3109 if (partial_obj_size == 0) {
3110 addr = bitmap->find_obj_beg(addr, src_region_end);
3111 assert(addr < src_region_end, "no objects start in src region");
3112 }
3113 return addr;
3114 }
3115
3116 // Must skip some live data.
3117 size_t words_to_skip = dest_addr - src_region_destination;
3118 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
3119
3120 if (partial_obj_size >= words_to_skip) {
3121 // All the live words to skip are part of the partial object.
3122 addr += words_to_skip;
3123 if (partial_obj_size == words_to_skip) {
3124 // Find the first live word past the partial object.
3125 addr = bitmap->find_obj_beg(addr, src_region_end);
3126 assert(addr < src_region_end, "wrong src region");
3127 }
3128 return addr;
3129 }
3130
3131 // Skip over the partial object (if any).
3132 if (partial_obj_size != 0) {
3133 words_to_skip -= partial_obj_size;
3134 addr += partial_obj_size;
3135 }
3136
3137 // Skip over live words due to objects that start in the region.
3138 addr = skip_live_words(addr, src_region_end, words_to_skip);
3139 assert(addr < src_region_end, "wrong src region");
3140 return addr;
3141 }
3142
3143 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
3144 SpaceId src_space_id,
3145 size_t beg_region,
3146 HeapWord* end_addr)
3147 {
3148 ParallelCompactData& sd = summary_data();
3149
3150 #ifdef ASSERT
3151 MutableSpace* const src_space = _space_info[src_space_id].space();
3152 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
3153 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
3154 "src_space_id does not match beg_addr");
3155 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
3156 "src_space_id does not match end_addr");
3157 #endif // #ifdef ASSERT
3158
3159 RegionData* const beg = sd.region(beg_region);
3160 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
3161
3162 // Regions up to new_top() are enqueued if they become available.
3163 HeapWord* const new_top = _space_info[src_space_id].new_top();
3164 RegionData* const enqueue_end =
3165 sd.addr_to_region_ptr(sd.region_align_up(new_top));
3166
3167 for (RegionData* cur = beg; cur < end; ++cur) {
3168 assert(cur->data_size() > 0, "region must have live data");
3169 cur->decrement_destination_count();
3170 if (cur < enqueue_end && cur->available() && cur->claim()) {
3171 cm->push_region(sd.region(cur));
3172 }
3173 }
3174 }
3175
3176 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
3177 SpaceId& src_space_id,
3178 HeapWord*& src_space_top,
3179 HeapWord* end_addr)
3180 {
3181 typedef ParallelCompactData::RegionData RegionData;
3182
3183 ParallelCompactData& sd = PSParallelCompact::summary_data();
3184 const size_t region_size = ParallelCompactData::RegionSize;
3185
3186 size_t src_region_idx = 0;
3187
3188 // Skip empty regions (if any) up to the top of the space.
3189 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
3190 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
3191 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
3192 const RegionData* const top_region_ptr =
3193 sd.addr_to_region_ptr(top_aligned_up);
3194 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
3195 ++src_region_ptr;
3196 }
3197
3198 if (src_region_ptr < top_region_ptr) {
3199 // The next source region is in the current space. Update src_region_idx
3200 // and the source address to match src_region_ptr.
3201 src_region_idx = sd.region(src_region_ptr);
3202 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
3203 if (src_region_addr > closure.source()) {
3204 closure.set_source(src_region_addr);
3205 }
3206 return src_region_idx;
3207 }
3208
3209 // Switch to a new source space and find the first non-empty region.
3210 unsigned int space_id = src_space_id + 1;
3211 assert(space_id < last_space_id, "not enough spaces");
3212
3213 HeapWord* const destination = closure.destination();
3214
3215 do {
3216 MutableSpace* space = _space_info[space_id].space();
3217 HeapWord* const bottom = space->bottom();
3218 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
3219
3220 // Iterate over the spaces that do not compact into themselves.
3221 if (bottom_cp->destination() != bottom) {
3222 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
3223 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
3224
3225 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
3226 if (src_cp->live_obj_size() > 0) {
3227 // Found it.
3228 assert(src_cp->destination() == destination,
3229 "first live obj in the space must match the destination");
3230 assert(src_cp->partial_obj_size() == 0,
3231 "a space cannot begin with a partial obj");
3232
3233 src_space_id = SpaceId(space_id);
3234 src_space_top = space->top();
3235 const size_t src_region_idx = sd.region(src_cp);
3236 closure.set_source(sd.region_to_addr(src_region_idx));
3237 return src_region_idx;
3238 } else {
3239 assert(src_cp->data_size() == 0, "sanity");
3240 }
3241 }
3242 }
3243 } while (++space_id < last_space_id);
3244
3245 assert(false, "no source region was found");
3246 return 0;
3247 }
3248
3249 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
3250 {
3251 typedef ParMarkBitMap::IterationStatus IterationStatus;
3252 const size_t RegionSize = ParallelCompactData::RegionSize;
3253 ParMarkBitMap* const bitmap = mark_bitmap();
3254 ParallelCompactData& sd = summary_data();
3255 RegionData* const region_ptr = sd.region(region_idx);
3256
3257 // Get the items needed to construct the closure.
3258 HeapWord* dest_addr = sd.region_to_addr(region_idx);
3259 SpaceId dest_space_id = space_id(dest_addr);
3260 ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
3261 HeapWord* new_top = _space_info[dest_space_id].new_top();
3262 assert(dest_addr < new_top, "sanity");
3263 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
3264
3265 // Get the source region and related info.
3266 size_t src_region_idx = region_ptr->source_region();
3267 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
3268 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
3269
3270 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3271 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
3272
3273 // Adjust src_region_idx to prepare for decrementing destination counts (the
3274 // destination count is not decremented when a region is copied to itself).
3275 if (src_region_idx == region_idx) {
3276 src_region_idx += 1;
3277 }
3278
3279 if (bitmap->is_unmarked(closure.source())) {
3280 // The first source word is in the middle of an object; copy the remainder
3281 // of the object or as much as will fit. The fact that pointer updates were
3282 // deferred will be noted when the object header is processed.
3283 HeapWord* const old_src_addr = closure.source();
3284 closure.copy_partial_obj();
3285 if (closure.is_full()) {
3286 decrement_destination_counts(cm, src_space_id, src_region_idx,
3287 closure.source());
3288 region_ptr->set_deferred_obj_addr(NULL);
3289 region_ptr->set_completed();
3290 return;
3291 }
3292
3293 HeapWord* const end_addr = sd.region_align_down(closure.source());
3294 if (sd.region_align_down(old_src_addr) != end_addr) {
3295 // The partial object was copied from more than one source region.
3296 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3297
3298 // Move to the next source region, possibly switching spaces as well. All
3299 // args except end_addr may be modified.
3300 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3301 end_addr);
3302 }
3303 }
3304
3305 do {
3306 HeapWord* const cur_addr = closure.source();
3307 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
3308 src_space_top);
3309 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
3310
3311 if (status == ParMarkBitMap::incomplete) {
3312 // The last obj that starts in the source region does not end in the
3313 // region.
3314 assert(closure.source() < end_addr, "sanity");
3315 HeapWord* const obj_beg = closure.source();
3316 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
3317 src_space_top);
3318 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
3319 if (obj_end < range_end) {
3320 // The end was found; the entire object will fit.
3321 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
3322 assert(status != ParMarkBitMap::would_overflow, "sanity");
3323 } else {
3324 // The end was not found; the object will not fit.
3325 assert(range_end < src_space_top, "obj cannot cross space boundary");
3326 status = ParMarkBitMap::would_overflow;
3327 }
3328 }
3329
3330 if (status == ParMarkBitMap::would_overflow) {
3331 // The last object did not fit. Note that interior oop updates were
3332 // deferred, then copy enough of the object to fill the region.
3333 region_ptr->set_deferred_obj_addr(closure.destination());
3334 status = closure.copy_until_full(); // copies from closure.source()
3335
3336 decrement_destination_counts(cm, src_space_id, src_region_idx,
3337 closure.source());
3338 region_ptr->set_completed();
3339 return;
3340 }
3341
3342 if (status == ParMarkBitMap::full) {
3343 decrement_destination_counts(cm, src_space_id, src_region_idx,
3344 closure.source());
3345 region_ptr->set_deferred_obj_addr(NULL);
3346 region_ptr->set_completed();
3347 return;
3348 }
3349
3350 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3351
3352 // Move to the next source region, possibly switching spaces as well. All
3353 // args except end_addr may be modified.
3354 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3355 end_addr);
3356 } while (true);
3357 }
3358
3359 void
3360 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
3361 const MutableSpace* sp = space(space_id);
3362 if (sp->is_empty()) {
3363 return;
3364 }
3365
3366 ParallelCompactData& sd = PSParallelCompact::summary_data();
3367 ParMarkBitMap* const bitmap = mark_bitmap();
3368 HeapWord* const dp_addr = dense_prefix(space_id);
3369 HeapWord* beg_addr = sp->bottom();
3370 HeapWord* end_addr = sp->top();
3371
3372 #ifdef ASSERT
3373 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
3374 if (cm->should_verify_only()) {
3375 VerifyUpdateClosure verify_update(cm, sp);
3376 bitmap->iterate(&verify_update, beg_addr, end_addr);
3377 return;
3378 }
3379
3380 if (cm->should_reset_only()) {
3381 ResetObjectsClosure reset_objects(cm);
3382 bitmap->iterate(&reset_objects, beg_addr, end_addr);
3383 return;
3384 }
3385 #endif
3386
3387 const size_t beg_region = sd.addr_to_region_idx(beg_addr);
3388 const size_t dp_region = sd.addr_to_region_idx(dp_addr);
3389 if (beg_region < dp_region) {
3390 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
3391 }
3392
3393 // The destination of the first live object that starts in the region is one
3394 // past the end of the partial object entering the region (if any).
3395 HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3396 HeapWord* const new_top = _space_info[space_id].new_top();
3397 assert(new_top >= dest_addr, "bad new_top value");
3398 const size_t words = pointer_delta(new_top, dest_addr);
3399
3400 if (words > 0) {
3401 ObjectStartArray* start_array = _space_info[space_id].start_array();
3402 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3403
3404 ParMarkBitMap::IterationStatus status;
3405 status = bitmap->iterate(&closure, dest_addr, end_addr);
3406 assert(status == ParMarkBitMap::full, "iteration not complete");
3407 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3408 "live objects skipped because closure is full");
3409 }
3410 }
3411
3412 jlong PSParallelCompact::millis_since_last_gc() {
3413 jlong ret_val = os::javaTimeMillis() - _time_of_last_gc;
3414 // XXX See note in genCollectedHeap::millis_since_last_gc().
3415 if (ret_val < 0) {
3416 NOT_PRODUCT(warning("time warp: %d", ret_val);)
3417 return 0;
3418 }
3419 return ret_val;
3420 }
3421
3422 void PSParallelCompact::reset_millis_since_last_gc() {
3423 _time_of_last_gc = os::javaTimeMillis();
3424 }
3425
3426 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3427 {
3428 if (source() != destination()) {
3429 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3430 Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3431 }
3432 update_state(words_remaining());
3433 assert(is_full(), "sanity");
3434 return ParMarkBitMap::full;
3435 }
3436
3437 void MoveAndUpdateClosure::copy_partial_obj()
3438 {
3439 size_t words = words_remaining();
3440
3441 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3442 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3443 if (end_addr < range_end) {
3444 words = bitmap()->obj_size(source(), end_addr);
3445 }
3446
3447 // This test is necessary; if omitted, the pointer updates to a partial object
3448 // that crosses the dense prefix boundary could be overwritten.
3449 if (source() != destination()) {
3450 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3451 Copy::aligned_conjoint_words(source(), destination(), words);
3452 }
3453 update_state(words);
3454 }
3455
3456 ParMarkBitMapClosure::IterationStatus
3457 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3458 assert(destination() != NULL, "sanity");
3459 assert(bitmap()->obj_size(addr) == words, "bad size");
3460
3461 _source = addr;
3462 assert(PSParallelCompact::summary_data().calc_new_pointer(source()) ==
3463 destination(), "wrong destination");
3464
3465 if (words > words_remaining()) {
3466 return ParMarkBitMap::would_overflow;
3467 }
3468
3469 // The start_array must be updated even if the object is not moving.
3470 if (_start_array != NULL) {
3471 _start_array->allocate_block(destination());
3472 }
3473
3474 if (destination() != source()) {
3475 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3476 Copy::aligned_conjoint_words(source(), destination(), words);
3477 }
3478
3479 oop moved_oop = (oop) destination();
3480 moved_oop->update_contents(compaction_manager());
3481 assert(moved_oop->is_oop_or_null(), "Object should be whole at this point");
3482
3483 update_state(words);
3484 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3485 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3486 }
3487
3488 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3489 ParCompactionManager* cm,
3490 PSParallelCompact::SpaceId space_id) :
3491 ParMarkBitMapClosure(mbm, cm),
3492 _space_id(space_id),
3493 _start_array(PSParallelCompact::start_array(space_id))
3494 {
3495 }
3496
3497 // Updates the references in the object to their new values.
3498 ParMarkBitMapClosure::IterationStatus
3499 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3500 do_addr(addr);
3501 return ParMarkBitMap::incomplete;
3502 }
3503
3504 // Verify the new location using the forwarding pointer
3505 // from MarkSweep::mark_sweep_phase2(). Set the mark_word
3506 // to the initial value.
3507 ParMarkBitMapClosure::IterationStatus
3508 PSParallelCompact::VerifyUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3509 // The second arg (words) is not used.
3510 oop obj = (oop) addr;
3511 HeapWord* forwarding_ptr = (HeapWord*) obj->mark()->decode_pointer();
3512 HeapWord* new_pointer = summary_data().calc_new_pointer(obj);
3513 if (forwarding_ptr == NULL) {
3514 // The object is dead or not moving.
3515 assert(bitmap()->is_unmarked(obj) || (new_pointer == (HeapWord*) obj),
3516 "Object liveness is wrong.");
3517 return ParMarkBitMap::incomplete;
3518 }
3519 assert(UseParallelOldGCDensePrefix ||
3520 (HeapMaximumCompactionInterval > 1) ||
3521 (MarkSweepAlwaysCompactCount > 1) ||
3522 (forwarding_ptr == new_pointer),
3523 "Calculation of new location is incorrect");
3524 return ParMarkBitMap::incomplete;
3525 }
3526
3527 // Reset objects modified for debug checking.
3528 ParMarkBitMapClosure::IterationStatus
3529 PSParallelCompact::ResetObjectsClosure::do_addr(HeapWord* addr, size_t words) {
3530 // The second arg (words) is not used.
3531 oop obj = (oop) addr;
3532 obj->init_mark();
3533 return ParMarkBitMap::incomplete;
3534 }
3535
3536 // Prepare for compaction. This method is executed once
3537 // (i.e., by a single thread) before compaction.
3538 // Save the updated location of the intArrayKlassObj for
3539 // filling holes in the dense prefix.
3540 void PSParallelCompact::compact_prologue() {
3541 _updated_int_array_klass_obj = (klassOop)
3542 summary_data().calc_new_pointer(Universe::intArrayKlassObj());
3543 }
3544