1 /*
2 * Copyright (c) 2005, 2013, 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/psPromotionManager.inline.hpp"
40 #include "gc_implementation/parallelScavenge/psScavenge.hpp"
41 #include "gc_implementation/parallelScavenge/psYoungGen.hpp"
42 #include "gc_implementation/shared/gcHeapSummary.hpp"
43 #include "gc_implementation/shared/gcTimer.hpp"
44 #include "gc_implementation/shared/gcTrace.hpp"
45 #include "gc_implementation/shared/gcTraceTime.hpp"
46 #include "gc_implementation/shared/isGCActiveMark.hpp"
47 #include "gc_interface/gcCause.hpp"
48 #include "memory/gcLocker.inline.hpp"
49 #include "memory/referencePolicy.hpp"
50 #include "memory/referenceProcessor.hpp"
51 #include "oops/methodData.hpp"
52 #include "oops/oop.inline.hpp"
53 #include "oops/oop.pcgc.inline.hpp"
54 #include "runtime/fprofiler.hpp"
55 #include "runtime/safepoint.hpp"
56 #include "runtime/vmThread.hpp"
57 #include "services/management.hpp"
58 #include "services/memoryService.hpp"
59 #include "services/memTracker.hpp"
60 #include "utilities/events.hpp"
61 #include "utilities/stack.inline.hpp"
62
63 #include <math.h>
64
65 // All sizes are in HeapWords.
66 const size_t ParallelCompactData::Log2RegionSize = 9; // 512 words
67 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
68 const size_t ParallelCompactData::RegionSizeBytes =
69 RegionSize << LogHeapWordSize;
70 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
71 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
72 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
73
74 const ParallelCompactData::RegionData::region_sz_t
75 ParallelCompactData::RegionData::dc_shift = 27;
76
77 const ParallelCompactData::RegionData::region_sz_t
78 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
79
80 const ParallelCompactData::RegionData::region_sz_t
81 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
82
83 const ParallelCompactData::RegionData::region_sz_t
84 ParallelCompactData::RegionData::los_mask = ~dc_mask;
85
86 const ParallelCompactData::RegionData::region_sz_t
87 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
88
89 const ParallelCompactData::RegionData::region_sz_t
90 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
91
92 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
93 bool PSParallelCompact::_print_phases = false;
94
95 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
96 Klass* PSParallelCompact::_updated_int_array_klass_obj = NULL;
97
98 double PSParallelCompact::_dwl_mean;
99 double PSParallelCompact::_dwl_std_dev;
100 double PSParallelCompact::_dwl_first_term;
101 double PSParallelCompact::_dwl_adjustment;
102 #ifdef ASSERT
103 bool PSParallelCompact::_dwl_initialized = false;
104 #endif // #ifdef ASSERT
105
106 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
107 HeapWord* destination)
108 {
109 assert(src_region_idx != 0, "invalid src_region_idx");
110 assert(partial_obj_size != 0, "invalid partial_obj_size argument");
111 assert(destination != NULL, "invalid destination argument");
112
113 _src_region_idx = src_region_idx;
114 _partial_obj_size = partial_obj_size;
115 _destination = destination;
116
117 // These fields may not be updated below, so make sure they're clear.
118 assert(_dest_region_addr == NULL, "should have been cleared");
119 assert(_first_src_addr == NULL, "should have been cleared");
120
121 // Determine the number of destination regions for the partial object.
122 HeapWord* const last_word = destination + partial_obj_size - 1;
123 const ParallelCompactData& sd = PSParallelCompact::summary_data();
124 HeapWord* const beg_region_addr = sd.region_align_down(destination);
125 HeapWord* const end_region_addr = sd.region_align_down(last_word);
126
127 if (beg_region_addr == end_region_addr) {
128 // One destination region.
129 _destination_count = 1;
130 if (end_region_addr == destination) {
131 // The destination falls on a region boundary, thus the first word of the
132 // partial object will be the first word copied to the destination region.
133 _dest_region_addr = end_region_addr;
134 _first_src_addr = sd.region_to_addr(src_region_idx);
135 }
136 } else {
137 // Two destination regions. When copied, the partial object will cross a
138 // destination region boundary, so a word somewhere within the partial
139 // object will be the first word copied to the second destination region.
140 _destination_count = 2;
141 _dest_region_addr = end_region_addr;
142 const size_t ofs = pointer_delta(end_region_addr, destination);
143 assert(ofs < _partial_obj_size, "sanity");
144 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
145 }
146 }
147
148 void SplitInfo::clear()
149 {
150 _src_region_idx = 0;
151 _partial_obj_size = 0;
152 _destination = NULL;
153 _destination_count = 0;
154 _dest_region_addr = NULL;
155 _first_src_addr = NULL;
156 assert(!is_valid(), "sanity");
157 }
158
159 #ifdef ASSERT
160 void SplitInfo::verify_clear()
161 {
162 assert(_src_region_idx == 0, "not clear");
163 assert(_partial_obj_size == 0, "not clear");
164 assert(_destination == NULL, "not clear");
165 assert(_destination_count == 0, "not clear");
166 assert(_dest_region_addr == NULL, "not clear");
167 assert(_first_src_addr == NULL, "not clear");
168 }
169 #endif // #ifdef ASSERT
170
171
172 void PSParallelCompact::print_on_error(outputStream* st) {
173 _mark_bitmap.print_on_error(st);
174 }
175
176 #ifndef PRODUCT
177 const char* PSParallelCompact::space_names[] = {
178 "old ", "eden", "from", "to "
179 };
180
181 void PSParallelCompact::print_region_ranges()
182 {
183 tty->print_cr("space bottom top end new_top");
184 tty->print_cr("------ ---------- ---------- ---------- ----------");
185
186 for (unsigned int id = 0; id < last_space_id; ++id) {
187 const MutableSpace* space = _space_info[id].space();
188 tty->print_cr("%u %s "
189 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
190 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
191 id, space_names[id],
192 summary_data().addr_to_region_idx(space->bottom()),
193 summary_data().addr_to_region_idx(space->top()),
194 summary_data().addr_to_region_idx(space->end()),
195 summary_data().addr_to_region_idx(_space_info[id].new_top()));
196 }
197 }
198
199 void
200 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
201 {
202 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7)
203 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5)
204
205 ParallelCompactData& sd = PSParallelCompact::summary_data();
206 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
207 tty->print_cr(REGION_IDX_FORMAT " " PTR_FORMAT " "
208 REGION_IDX_FORMAT " " PTR_FORMAT " "
209 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
210 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
211 i, c->data_location(), dci, c->destination(),
212 c->partial_obj_size(), c->live_obj_size(),
213 c->data_size(), c->source_region(), c->destination_count());
214
215 #undef REGION_IDX_FORMAT
216 #undef REGION_DATA_FORMAT
217 }
218
219 void
220 print_generic_summary_data(ParallelCompactData& summary_data,
221 HeapWord* const beg_addr,
222 HeapWord* const end_addr)
223 {
224 size_t total_words = 0;
225 size_t i = summary_data.addr_to_region_idx(beg_addr);
226 const size_t last = summary_data.addr_to_region_idx(end_addr);
227 HeapWord* pdest = 0;
228
229 while (i <= last) {
230 ParallelCompactData::RegionData* c = summary_data.region(i);
231 if (c->data_size() != 0 || c->destination() != pdest) {
232 print_generic_summary_region(i, c);
233 total_words += c->data_size();
234 pdest = c->destination();
235 }
236 ++i;
237 }
238
239 tty->print_cr("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
240 }
241
242 void
243 print_generic_summary_data(ParallelCompactData& summary_data,
244 SpaceInfo* space_info)
245 {
246 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
247 const MutableSpace* space = space_info[id].space();
248 print_generic_summary_data(summary_data, space->bottom(),
249 MAX2(space->top(), space_info[id].new_top()));
250 }
251 }
252
253 void
254 print_initial_summary_region(size_t i,
255 const ParallelCompactData::RegionData* c,
256 bool newline = true)
257 {
258 tty->print(SIZE_FORMAT_W(5) " " PTR_FORMAT " "
259 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " "
260 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
261 i, c->destination(),
262 c->partial_obj_size(), c->live_obj_size(),
263 c->data_size(), c->source_region(), c->destination_count());
264 if (newline) tty->cr();
265 }
266
267 void
268 print_initial_summary_data(ParallelCompactData& summary_data,
269 const MutableSpace* space) {
270 if (space->top() == space->bottom()) {
271 return;
272 }
273
274 const size_t region_size = ParallelCompactData::RegionSize;
275 typedef ParallelCompactData::RegionData RegionData;
276 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
277 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
278 const RegionData* c = summary_data.region(end_region - 1);
279 HeapWord* end_addr = c->destination() + c->data_size();
280 const size_t live_in_space = pointer_delta(end_addr, space->bottom());
281
282 // Print (and count) the full regions at the beginning of the space.
283 size_t full_region_count = 0;
284 size_t i = summary_data.addr_to_region_idx(space->bottom());
285 while (i < end_region && summary_data.region(i)->data_size() == region_size) {
286 print_initial_summary_region(i, summary_data.region(i));
287 ++full_region_count;
288 ++i;
289 }
290
291 size_t live_to_right = live_in_space - full_region_count * region_size;
292
293 double max_reclaimed_ratio = 0.0;
294 size_t max_reclaimed_ratio_region = 0;
295 size_t max_dead_to_right = 0;
296 size_t max_live_to_right = 0;
297
298 // Print the 'reclaimed ratio' for regions while there is something live in
299 // the region or to the right of it. The remaining regions are empty (and
300 // uninteresting), and computing the ratio will result in division by 0.
301 while (i < end_region && live_to_right > 0) {
302 c = summary_data.region(i);
303 HeapWord* const region_addr = summary_data.region_to_addr(i);
304 const size_t used_to_right = pointer_delta(space->top(), region_addr);
305 const size_t dead_to_right = used_to_right - live_to_right;
306 const double reclaimed_ratio = double(dead_to_right) / live_to_right;
307
308 if (reclaimed_ratio > max_reclaimed_ratio) {
309 max_reclaimed_ratio = reclaimed_ratio;
310 max_reclaimed_ratio_region = i;
311 max_dead_to_right = dead_to_right;
312 max_live_to_right = live_to_right;
313 }
314
315 print_initial_summary_region(i, c, false);
316 tty->print_cr(" %12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
317 reclaimed_ratio, dead_to_right, live_to_right);
318
319 live_to_right -= c->data_size();
320 ++i;
321 }
322
323 // Any remaining regions are empty. Print one more if there is one.
324 if (i < end_region) {
325 print_initial_summary_region(i, summary_data.region(i));
326 }
327
328 tty->print_cr("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " "
329 "l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
330 max_reclaimed_ratio_region, max_dead_to_right,
331 max_live_to_right, max_reclaimed_ratio);
332 }
333
334 void
335 print_initial_summary_data(ParallelCompactData& summary_data,
336 SpaceInfo* space_info) {
337 unsigned int id = PSParallelCompact::old_space_id;
338 const MutableSpace* space;
339 do {
340 space = space_info[id].space();
341 print_initial_summary_data(summary_data, space);
342 } while (++id < PSParallelCompact::eden_space_id);
343
344 do {
345 space = space_info[id].space();
346 print_generic_summary_data(summary_data, space->bottom(), space->top());
347 } while (++id < PSParallelCompact::last_space_id);
348 }
349 #endif // #ifndef PRODUCT
350
351 #ifdef ASSERT
352 size_t add_obj_count;
353 size_t add_obj_size;
354 size_t mark_bitmap_count;
355 size_t mark_bitmap_size;
356 #endif // #ifdef ASSERT
357
358 ParallelCompactData::ParallelCompactData()
359 {
360 _region_start = 0;
361
362 _region_vspace = 0;
363 _reserved_byte_size = 0;
364 _region_data = 0;
365 _region_count = 0;
366 }
367
368 bool ParallelCompactData::initialize(MemRegion covered_region)
369 {
370 _region_start = covered_region.start();
371 const size_t region_size = covered_region.word_size();
372 DEBUG_ONLY(_region_end = _region_start + region_size;)
373
374 assert(region_align_down(_region_start) == _region_start,
375 "region start not aligned");
376 assert((region_size & RegionSizeOffsetMask) == 0,
377 "region size not a multiple of RegionSize");
378
379 bool result = initialize_region_data(region_size);
380
381 return result;
382 }
383
384 PSVirtualSpace*
385 ParallelCompactData::create_vspace(size_t count, size_t element_size)
386 {
387 const size_t raw_bytes = count * element_size;
388 const size_t page_sz = os::page_size_for_region(raw_bytes, raw_bytes, 10);
389 const size_t granularity = os::vm_allocation_granularity();
390 _reserved_byte_size = align_size_up(raw_bytes, MAX2(page_sz, granularity));
391
392 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
393 MAX2(page_sz, granularity);
394 ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0);
395 os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(),
396 rs.size());
397
398 MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
399
400 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
401 if (vspace != 0) {
402 if (vspace->expand_by(_reserved_byte_size)) {
403 return vspace;
404 }
405 delete vspace;
406 // Release memory reserved in the space.
407 rs.release();
408 }
409
410 return 0;
411 }
412
413 bool ParallelCompactData::initialize_region_data(size_t region_size)
414 {
415 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
416 _region_vspace = create_vspace(count, sizeof(RegionData));
417 if (_region_vspace != 0) {
418 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
419 _region_count = count;
420 return true;
421 }
422 return false;
423 }
424
425 void ParallelCompactData::clear()
426 {
427 memset(_region_data, 0, _region_vspace->committed_size());
428 }
429
430 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
431 assert(beg_region <= _region_count, "beg_region out of range");
432 assert(end_region <= _region_count, "end_region out of range");
433
434 const size_t region_cnt = end_region - beg_region;
435 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
436 }
437
438 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
439 {
440 const RegionData* cur_cp = region(region_idx);
441 const RegionData* const end_cp = region(region_count() - 1);
442
443 HeapWord* result = region_to_addr(region_idx);
444 if (cur_cp < end_cp) {
445 do {
446 result += cur_cp->partial_obj_size();
447 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
448 }
449 return result;
450 }
451
452 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
453 {
454 const size_t obj_ofs = pointer_delta(addr, _region_start);
455 const size_t beg_region = obj_ofs >> Log2RegionSize;
456 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
457
458 DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
459 DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
460
461 if (beg_region == end_region) {
462 // All in one region.
463 _region_data[beg_region].add_live_obj(len);
464 return;
465 }
466
467 // First region.
468 const size_t beg_ofs = region_offset(addr);
469 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
470
471 Klass* klass = ((oop)addr)->klass();
472 // Middle regions--completely spanned by this object.
473 for (size_t region = beg_region + 1; region < end_region; ++region) {
474 _region_data[region].set_partial_obj_size(RegionSize);
475 _region_data[region].set_partial_obj_addr(addr);
476 }
477
478 // Last region.
479 const size_t end_ofs = region_offset(addr + len - 1);
480 _region_data[end_region].set_partial_obj_size(end_ofs + 1);
481 _region_data[end_region].set_partial_obj_addr(addr);
482 }
483
484 void
485 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
486 {
487 assert(region_offset(beg) == 0, "not RegionSize aligned");
488 assert(region_offset(end) == 0, "not RegionSize aligned");
489
490 size_t cur_region = addr_to_region_idx(beg);
491 const size_t end_region = addr_to_region_idx(end);
492 HeapWord* addr = beg;
493 while (cur_region < end_region) {
494 _region_data[cur_region].set_destination(addr);
495 _region_data[cur_region].set_destination_count(0);
496 _region_data[cur_region].set_source_region(cur_region);
497 _region_data[cur_region].set_data_location(addr);
498
499 // Update live_obj_size so the region appears completely full.
500 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
501 _region_data[cur_region].set_live_obj_size(live_size);
502
503 ++cur_region;
504 addr += RegionSize;
505 }
506 }
507
508 // Find the point at which a space can be split and, if necessary, record the
509 // split point.
510 //
511 // If the current src region (which overflowed the destination space) doesn't
512 // have a partial object, the split point is at the beginning of the current src
513 // region (an "easy" split, no extra bookkeeping required).
514 //
515 // If the current src region has a partial object, the split point is in the
516 // region where that partial object starts (call it the split_region). If
517 // split_region has a partial object, then the split point is just after that
518 // partial object (a "hard" split where we have to record the split data and
519 // zero the partial_obj_size field). With a "hard" split, we know that the
520 // partial_obj ends within split_region because the partial object that caused
521 // the overflow starts in split_region. If split_region doesn't have a partial
522 // obj, then the split is at the beginning of split_region (another "easy"
523 // split).
524 HeapWord*
525 ParallelCompactData::summarize_split_space(size_t src_region,
526 SplitInfo& split_info,
527 HeapWord* destination,
528 HeapWord* target_end,
529 HeapWord** target_next)
530 {
531 assert(destination <= target_end, "sanity");
532 assert(destination + _region_data[src_region].data_size() > target_end,
533 "region should not fit into target space");
534 assert(is_region_aligned(target_end), "sanity");
535
536 size_t split_region = src_region;
537 HeapWord* split_destination = destination;
538 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
539
540 if (destination + partial_obj_size > target_end) {
541 // The split point is just after the partial object (if any) in the
542 // src_region that contains the start of the object that overflowed the
543 // destination space.
544 //
545 // Find the start of the "overflow" object and set split_region to the
546 // region containing it.
547 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
548 split_region = addr_to_region_idx(overflow_obj);
549
550 // Clear the source_region field of all destination regions whose first word
551 // came from data after the split point (a non-null source_region field
552 // implies a region must be filled).
553 //
554 // An alternative to the simple loop below: clear during post_compact(),
555 // which uses memcpy instead of individual stores, and is easy to
556 // parallelize. (The downside is that it clears the entire RegionData
557 // object as opposed to just one field.)
558 //
559 // post_compact() would have to clear the summary data up to the highest
560 // address that was written during the summary phase, which would be
561 //
562 // max(top, max(new_top, clear_top))
563 //
564 // where clear_top is a new field in SpaceInfo. Would have to set clear_top
565 // to target_end.
566 const RegionData* const sr = region(split_region);
567 const size_t beg_idx =
568 addr_to_region_idx(region_align_up(sr->destination() +
569 sr->partial_obj_size()));
570 const size_t end_idx = addr_to_region_idx(target_end);
571
572 if (TraceParallelOldGCSummaryPhase) {
573 gclog_or_tty->print_cr("split: clearing source_region field in ["
574 SIZE_FORMAT ", " SIZE_FORMAT ")",
575 beg_idx, end_idx);
576 }
577 for (size_t idx = beg_idx; idx < end_idx; ++idx) {
578 _region_data[idx].set_source_region(0);
579 }
580
581 // Set split_destination and partial_obj_size to reflect the split region.
582 split_destination = sr->destination();
583 partial_obj_size = sr->partial_obj_size();
584 }
585
586 // The split is recorded only if a partial object extends onto the region.
587 if (partial_obj_size != 0) {
588 _region_data[split_region].set_partial_obj_size(0);
589 split_info.record(split_region, partial_obj_size, split_destination);
590 }
591
592 // Setup the continuation addresses.
593 *target_next = split_destination + partial_obj_size;
594 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
595
596 if (TraceParallelOldGCSummaryPhase) {
597 const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
598 gclog_or_tty->print_cr("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT
599 " pos=" SIZE_FORMAT,
600 split_type, source_next, split_region,
601 partial_obj_size);
602 gclog_or_tty->print_cr("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT
603 " tn=" PTR_FORMAT,
604 split_type, split_destination,
605 addr_to_region_idx(split_destination),
606 *target_next);
607
608 if (partial_obj_size != 0) {
609 HeapWord* const po_beg = split_info.destination();
610 HeapWord* const po_end = po_beg + split_info.partial_obj_size();
611 gclog_or_tty->print_cr("%s split: "
612 "po_beg=" PTR_FORMAT " " SIZE_FORMAT " "
613 "po_end=" PTR_FORMAT " " SIZE_FORMAT,
614 split_type,
615 po_beg, addr_to_region_idx(po_beg),
616 po_end, addr_to_region_idx(po_end));
617 }
618 }
619
620 return source_next;
621 }
622
623 bool ParallelCompactData::summarize(SplitInfo& split_info,
624 HeapWord* source_beg, HeapWord* source_end,
625 HeapWord** source_next,
626 HeapWord* target_beg, HeapWord* target_end,
627 HeapWord** target_next)
628 {
629 if (TraceParallelOldGCSummaryPhase) {
630 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
631 tty->print_cr("sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
632 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
633 source_beg, source_end, source_next_val,
634 target_beg, target_end, *target_next);
635 }
636
637 size_t cur_region = addr_to_region_idx(source_beg);
638 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
639
640 HeapWord *dest_addr = target_beg;
641 while (cur_region < end_region) {
642 // The destination must be set even if the region has no data.
643 _region_data[cur_region].set_destination(dest_addr);
644
645 size_t words = _region_data[cur_region].data_size();
646 if (words > 0) {
647 // If cur_region does not fit entirely into the target space, find a point
648 // at which the source space can be 'split' so that part is copied to the
649 // target space and the rest is copied elsewhere.
650 if (dest_addr + words > target_end) {
651 assert(source_next != NULL, "source_next is NULL when splitting");
652 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
653 target_end, target_next);
654 return false;
655 }
656
657 // Compute the destination_count for cur_region, and if necessary, update
658 // source_region for a destination region. The source_region field is
659 // updated if cur_region is the first (left-most) region to be copied to a
660 // destination region.
661 //
662 // The destination_count calculation is a bit subtle. A region that has
663 // data that compacts into itself does not count itself as a destination.
664 // This maintains the invariant that a zero count means the region is
665 // available and can be claimed and then filled.
666 uint destination_count = 0;
667 if (split_info.is_split(cur_region)) {
668 // The current region has been split: the partial object will be copied
669 // to one destination space and the remaining data will be copied to
670 // another destination space. Adjust the initial destination_count and,
671 // if necessary, set the source_region field if the partial object will
672 // cross a destination region boundary.
673 destination_count = split_info.destination_count();
674 if (destination_count == 2) {
675 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
676 _region_data[dest_idx].set_source_region(cur_region);
677 }
678 }
679
680 HeapWord* const last_addr = dest_addr + words - 1;
681 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
682 const size_t dest_region_2 = addr_to_region_idx(last_addr);
683
684 // Initially assume that the destination regions will be the same and
685 // adjust the value below if necessary. Under this assumption, if
686 // cur_region == dest_region_2, then cur_region will be compacted
687 // completely into itself.
688 destination_count += cur_region == dest_region_2 ? 0 : 1;
689 if (dest_region_1 != dest_region_2) {
690 // Destination regions differ; adjust destination_count.
691 destination_count += 1;
692 // Data from cur_region will be copied to the start of dest_region_2.
693 _region_data[dest_region_2].set_source_region(cur_region);
694 } else if (region_offset(dest_addr) == 0) {
695 // Data from cur_region will be copied to the start of the destination
696 // region.
697 _region_data[dest_region_1].set_source_region(cur_region);
698 }
699
700 _region_data[cur_region].set_destination_count(destination_count);
701 _region_data[cur_region].set_data_location(region_to_addr(cur_region));
702 dest_addr += words;
703 }
704
705 ++cur_region;
706 }
707
708 *target_next = dest_addr;
709 return true;
710 }
711
712 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) {
713 assert(addr != NULL, "Should detect NULL oop earlier");
714 assert(PSParallelCompact::gc_heap()->is_in(addr), "addr not in heap");
715 #ifdef ASSERT
716 if (PSParallelCompact::mark_bitmap()->is_unmarked(addr)) {
717 gclog_or_tty->print_cr("calc_new_pointer:: addr " PTR_FORMAT, addr);
718 }
719 #endif
720 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "obj not marked");
721
722 // Region covering the object.
723 size_t region_index = addr_to_region_idx(addr);
724 const RegionData* const region_ptr = region(region_index);
725 HeapWord* const region_addr = region_align_down(addr);
726
727 assert(addr < region_addr + RegionSize, "Region does not cover object");
728 assert(addr_to_region_ptr(region_addr) == region_ptr, "sanity check");
729
730 HeapWord* result = region_ptr->destination();
731
732 // If all the data in the region is live, then the new location of the object
733 // can be calculated from the destination of the region plus the offset of the
734 // object in the region.
735 if (region_ptr->data_size() == RegionSize) {
736 result += pointer_delta(addr, region_addr);
737 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result);)
738 return result;
739 }
740
741 // The new location of the object is
742 // region destination +
743 // size of the partial object extending onto the region +
744 // sizes of the live objects in the Region that are to the left of addr
745 const size_t partial_obj_size = region_ptr->partial_obj_size();
746 HeapWord* const search_start = region_addr + partial_obj_size;
747
748 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
749 size_t live_to_left = bitmap->live_words_in_range(search_start, oop(addr));
750
751 result += partial_obj_size + live_to_left;
752 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result);)
753 return result;
754 }
755
756 #ifdef ASSERT
757 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
758 {
759 const size_t* const beg = (const size_t*)vspace->committed_low_addr();
760 const size_t* const end = (const size_t*)vspace->committed_high_addr();
761 for (const size_t* p = beg; p < end; ++p) {
762 assert(*p == 0, "not zero");
763 }
764 }
765
766 void ParallelCompactData::verify_clear()
767 {
768 verify_clear(_region_vspace);
769 }
770 #endif // #ifdef ASSERT
771
772 #ifdef NOT_PRODUCT
773 ParallelCompactData::RegionData* debug_region(size_t region_index) {
774 ParallelCompactData& sd = PSParallelCompact::summary_data();
775 return sd.region(region_index);
776 }
777 #endif
778
779 STWGCTimer PSParallelCompact::_gc_timer;
780 ParallelOldTracer PSParallelCompact::_gc_tracer;
781 elapsedTimer PSParallelCompact::_accumulated_time;
782 unsigned int PSParallelCompact::_total_invocations = 0;
783 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
784 jlong PSParallelCompact::_time_of_last_gc = 0;
785 CollectorCounters* PSParallelCompact::_counters = NULL;
786 ParMarkBitMap PSParallelCompact::_mark_bitmap;
787 ParallelCompactData PSParallelCompact::_summary_data;
788
789 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
790
791 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
792
793 void PSParallelCompact::KeepAliveClosure::do_oop(oop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
794 void PSParallelCompact::KeepAliveClosure::do_oop(narrowOop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
795
796 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_pointer_closure;
797 PSParallelCompact::AdjustKlassClosure PSParallelCompact::_adjust_klass_closure;
798
799 void PSParallelCompact::AdjustPointerClosure::do_oop(oop* p) { adjust_pointer(p); }
800 void PSParallelCompact::AdjustPointerClosure::do_oop(narrowOop* p) { adjust_pointer(p); }
801
802 void PSParallelCompact::FollowStackClosure::do_void() { _compaction_manager->follow_marking_stacks(); }
803
804 void PSParallelCompact::MarkAndPushClosure::do_oop(oop* p) {
805 mark_and_push(_compaction_manager, p);
806 }
807 void PSParallelCompact::MarkAndPushClosure::do_oop(narrowOop* p) { mark_and_push(_compaction_manager, p); }
808
809 void PSParallelCompact::FollowKlassClosure::do_klass(Klass* klass) {
810 klass->oops_do(_mark_and_push_closure);
811 }
812 void PSParallelCompact::AdjustKlassClosure::do_klass(Klass* klass) {
813 klass->oops_do(&PSParallelCompact::_adjust_pointer_closure);
814 }
815
816 void PSParallelCompact::post_initialize() {
817 ParallelScavengeHeap* heap = gc_heap();
818 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
819
820 MemRegion mr = heap->reserved_region();
821 _ref_processor =
822 new ReferenceProcessor(mr, // span
823 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
824 (int) ParallelGCThreads, // mt processing degree
825 true, // mt discovery
826 (int) ParallelGCThreads, // mt discovery degree
827 true, // atomic_discovery
828 &_is_alive_closure, // non-header is alive closure
829 false); // write barrier for next field updates
830 _counters = new CollectorCounters("PSParallelCompact", 1);
831
832 // Initialize static fields in ParCompactionManager.
833 ParCompactionManager::initialize(mark_bitmap());
834 }
835
836 bool PSParallelCompact::initialize() {
837 ParallelScavengeHeap* heap = gc_heap();
838 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
839 MemRegion mr = heap->reserved_region();
840
841 // Was the old gen get allocated successfully?
842 if (!heap->old_gen()->is_allocated()) {
843 return false;
844 }
845
846 initialize_space_info();
847 initialize_dead_wood_limiter();
848
849 if (!_mark_bitmap.initialize(mr)) {
850 vm_shutdown_during_initialization(
851 err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
852 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
853 _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
854 return false;
855 }
856
857 if (!_summary_data.initialize(mr)) {
858 vm_shutdown_during_initialization(
859 err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
860 "garbage collection for the requested " SIZE_FORMAT "KB heap.",
861 _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
862 return false;
863 }
864
865 return true;
866 }
867
868 void PSParallelCompact::initialize_space_info()
869 {
870 memset(&_space_info, 0, sizeof(_space_info));
871
872 ParallelScavengeHeap* heap = gc_heap();
873 PSYoungGen* young_gen = heap->young_gen();
874
875 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
876 _space_info[eden_space_id].set_space(young_gen->eden_space());
877 _space_info[from_space_id].set_space(young_gen->from_space());
878 _space_info[to_space_id].set_space(young_gen->to_space());
879
880 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
881 }
882
883 void PSParallelCompact::initialize_dead_wood_limiter()
884 {
885 const size_t max = 100;
886 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
887 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
888 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
889 DEBUG_ONLY(_dwl_initialized = true;)
890 _dwl_adjustment = normal_distribution(1.0);
891 }
892
893 // Simple class for storing info about the heap at the start of GC, to be used
894 // after GC for comparison/printing.
895 class PreGCValues {
896 public:
897 PreGCValues() { }
898 PreGCValues(ParallelScavengeHeap* heap) { fill(heap); }
899
900 void fill(ParallelScavengeHeap* heap) {
901 _heap_used = heap->used();
902 _young_gen_used = heap->young_gen()->used_in_bytes();
903 _old_gen_used = heap->old_gen()->used_in_bytes();
904 _metadata_used = MetaspaceAux::allocated_used_bytes();
905 };
906
907 size_t heap_used() const { return _heap_used; }
908 size_t young_gen_used() const { return _young_gen_used; }
909 size_t old_gen_used() const { return _old_gen_used; }
910 size_t metadata_used() const { return _metadata_used; }
911
912 private:
913 size_t _heap_used;
914 size_t _young_gen_used;
915 size_t _old_gen_used;
916 size_t _metadata_used;
917 };
918
919 void
920 PSParallelCompact::clear_data_covering_space(SpaceId id)
921 {
922 // At this point, top is the value before GC, new_top() is the value that will
923 // be set at the end of GC. The marking bitmap is cleared to top; nothing
924 // should be marked above top. The summary data is cleared to the larger of
925 // top & new_top.
926 MutableSpace* const space = _space_info[id].space();
927 HeapWord* const bot = space->bottom();
928 HeapWord* const top = space->top();
929 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
930
931 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
932 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
933 _mark_bitmap.clear_range(beg_bit, end_bit);
934
935 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
936 const size_t end_region =
937 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
938 _summary_data.clear_range(beg_region, end_region);
939
940 // Clear the data used to 'split' regions.
941 SplitInfo& split_info = _space_info[id].split_info();
942 if (split_info.is_valid()) {
943 split_info.clear();
944 }
945 DEBUG_ONLY(split_info.verify_clear();)
946 }
947
948 void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values)
949 {
950 // Update the from & to space pointers in space_info, since they are swapped
951 // at each young gen gc. Do the update unconditionally (even though a
952 // promotion failure does not swap spaces) because an unknown number of minor
953 // collections will have swapped the spaces an unknown number of times.
954 GCTraceTime tm("pre compact", print_phases(), true, &_gc_timer);
955 ParallelScavengeHeap* heap = gc_heap();
956 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
957 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
958
959 pre_gc_values->fill(heap);
960
961 DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
962 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
963
964 // Increment the invocation count
965 heap->increment_total_collections(true);
966
967 // We need to track unique mark sweep invocations as well.
968 _total_invocations++;
969
970 heap->print_heap_before_gc();
971 heap->trace_heap_before_gc(&_gc_tracer);
972
973 // Fill in TLABs
974 heap->accumulate_statistics_all_tlabs();
975 heap->ensure_parsability(true); // retire TLABs
976
977 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
978 HandleMark hm; // Discard invalid handles created during verification
979 Universe::verify(" VerifyBeforeGC:");
980 }
981
982 // Verify object start arrays
983 if (VerifyObjectStartArray &&
984 VerifyBeforeGC) {
985 heap->old_gen()->verify_object_start_array();
986 }
987
988 DEBUG_ONLY(mark_bitmap()->verify_clear();)
989 DEBUG_ONLY(summary_data().verify_clear();)
990
991 // Have worker threads release resources the next time they run a task.
992 gc_task_manager()->release_all_resources();
993 }
994
995 void PSParallelCompact::post_compact()
996 {
997 GCTraceTime tm("post compact", print_phases(), true, &_gc_timer);
998
999 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1000 // Clear the marking bitmap, summary data and split info.
1001 clear_data_covering_space(SpaceId(id));
1002 // Update top(). Must be done after clearing the bitmap and summary data.
1003 _space_info[id].publish_new_top();
1004 }
1005
1006 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1007 MutableSpace* const from_space = _space_info[from_space_id].space();
1008 MutableSpace* const to_space = _space_info[to_space_id].space();
1009
1010 ParallelScavengeHeap* heap = gc_heap();
1011 bool eden_empty = eden_space->is_empty();
1012 if (!eden_empty) {
1013 eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1014 heap->young_gen(), heap->old_gen());
1015 }
1016
1017 // Update heap occupancy information which is used as input to the soft ref
1018 // clearing policy at the next gc.
1019 Universe::update_heap_info_at_gc();
1020
1021 bool young_gen_empty = eden_empty && from_space->is_empty() &&
1022 to_space->is_empty();
1023
1024 BarrierSet* bs = heap->barrier_set();
1025 if (bs->is_a(BarrierSet::ModRef)) {
1026 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
1027 MemRegion old_mr = heap->old_gen()->reserved();
1028
1029 if (young_gen_empty) {
1030 modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
1031 } else {
1032 modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1033 }
1034 }
1035
1036 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1037 ClassLoaderDataGraph::purge();
1038 MetaspaceAux::verify_metrics();
1039
1040 Threads::gc_epilogue();
1041 CodeCache::gc_epilogue();
1042 JvmtiExport::gc_epilogue();
1043
1044 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1045
1046 ref_processor()->enqueue_discovered_references(NULL);
1047
1048 if (ZapUnusedHeapArea) {
1049 heap->gen_mangle_unused_area();
1050 }
1051
1052 // Update time of last GC
1053 reset_millis_since_last_gc();
1054 }
1055
1056 HeapWord*
1057 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1058 bool maximum_compaction)
1059 {
1060 const size_t region_size = ParallelCompactData::RegionSize;
1061 const ParallelCompactData& sd = summary_data();
1062
1063 const MutableSpace* const space = _space_info[id].space();
1064 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1065 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1066 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1067
1068 // Skip full regions at the beginning of the space--they are necessarily part
1069 // of the dense prefix.
1070 size_t full_count = 0;
1071 const RegionData* cp;
1072 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1073 ++full_count;
1074 }
1075
1076 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1077 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1078 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1079 if (maximum_compaction || cp == end_cp || interval_ended) {
1080 _maximum_compaction_gc_num = total_invocations();
1081 return sd.region_to_addr(cp);
1082 }
1083
1084 HeapWord* const new_top = _space_info[id].new_top();
1085 const size_t space_live = pointer_delta(new_top, space->bottom());
1086 const size_t space_used = space->used_in_words();
1087 const size_t space_capacity = space->capacity_in_words();
1088
1089 const double cur_density = double(space_live) / space_capacity;
1090 const double deadwood_density =
1091 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1092 const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1093
1094 if (TraceParallelOldGCDensePrefix) {
1095 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1096 cur_density, deadwood_density, deadwood_goal);
1097 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1098 "space_cap=" SIZE_FORMAT,
1099 space_live, space_used,
1100 space_capacity);
1101 }
1102
1103 // XXX - Use binary search?
1104 HeapWord* dense_prefix = sd.region_to_addr(cp);
1105 const RegionData* full_cp = cp;
1106 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1107 while (cp < end_cp) {
1108 HeapWord* region_destination = cp->destination();
1109 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1110 if (TraceParallelOldGCDensePrefix && Verbose) {
1111 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1112 "dp=" SIZE_FORMAT_W(8) " " "cdw=" SIZE_FORMAT_W(8),
1113 sd.region(cp), region_destination,
1114 dense_prefix, cur_deadwood);
1115 }
1116
1117 if (cur_deadwood >= deadwood_goal) {
1118 // Found the region that has the correct amount of deadwood to the left.
1119 // This typically occurs after crossing a fairly sparse set of regions, so
1120 // iterate backwards over those sparse regions, looking for the region
1121 // that has the lowest density of live objects 'to the right.'
1122 size_t space_to_left = sd.region(cp) * region_size;
1123 size_t live_to_left = space_to_left - cur_deadwood;
1124 size_t space_to_right = space_capacity - space_to_left;
1125 size_t live_to_right = space_live - live_to_left;
1126 double density_to_right = double(live_to_right) / space_to_right;
1127 while (cp > full_cp) {
1128 --cp;
1129 const size_t prev_region_live_to_right = live_to_right -
1130 cp->data_size();
1131 const size_t prev_region_space_to_right = space_to_right + region_size;
1132 double prev_region_density_to_right =
1133 double(prev_region_live_to_right) / prev_region_space_to_right;
1134 if (density_to_right <= prev_region_density_to_right) {
1135 return dense_prefix;
1136 }
1137 if (TraceParallelOldGCDensePrefix && Verbose) {
1138 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1139 "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1140 prev_region_density_to_right);
1141 }
1142 dense_prefix -= region_size;
1143 live_to_right = prev_region_live_to_right;
1144 space_to_right = prev_region_space_to_right;
1145 density_to_right = prev_region_density_to_right;
1146 }
1147 return dense_prefix;
1148 }
1149
1150 dense_prefix += region_size;
1151 ++cp;
1152 }
1153
1154 return dense_prefix;
1155 }
1156
1157 #ifndef PRODUCT
1158 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1159 const SpaceId id,
1160 const bool maximum_compaction,
1161 HeapWord* const addr)
1162 {
1163 const size_t region_idx = summary_data().addr_to_region_idx(addr);
1164 RegionData* const cp = summary_data().region(region_idx);
1165 const MutableSpace* const space = _space_info[id].space();
1166 HeapWord* const new_top = _space_info[id].new_top();
1167
1168 const size_t space_live = pointer_delta(new_top, space->bottom());
1169 const size_t dead_to_left = pointer_delta(addr, cp->destination());
1170 const size_t space_cap = space->capacity_in_words();
1171 const double dead_to_left_pct = double(dead_to_left) / space_cap;
1172 const size_t live_to_right = new_top - cp->destination();
1173 const size_t dead_to_right = space->top() - addr - live_to_right;
1174
1175 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1176 "spl=" SIZE_FORMAT " "
1177 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1178 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1179 " ratio=%10.8f",
1180 algorithm, addr, region_idx,
1181 space_live,
1182 dead_to_left, dead_to_left_pct,
1183 dead_to_right, live_to_right,
1184 double(dead_to_right) / live_to_right);
1185 }
1186 #endif // #ifndef PRODUCT
1187
1188 // Return a fraction indicating how much of the generation can be treated as
1189 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution
1190 // based on the density of live objects in the generation to determine a limit,
1191 // which is then adjusted so the return value is min_percent when the density is
1192 // 1.
1193 //
1194 // The following table shows some return values for a different values of the
1195 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1196 // min_percent is 1.
1197 //
1198 // fraction allowed as dead wood
1199 // -----------------------------------------------------------------
1200 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1201 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1202 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1203 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1204 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1205 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1206 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1207 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1208 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1209 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1210 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1211 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1212 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1213 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1214 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1215 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1216 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1217 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1218 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1219 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1220 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1221 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1222 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1223
1224 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1225 {
1226 assert(_dwl_initialized, "uninitialized");
1227
1228 // The raw limit is the value of the normal distribution at x = density.
1229 const double raw_limit = normal_distribution(density);
1230
1231 // Adjust the raw limit so it becomes the minimum when the density is 1.
1232 //
1233 // First subtract the adjustment value (which is simply the precomputed value
1234 // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1235 // Then add the minimum value, so the minimum is returned when the density is
1236 // 1. Finally, prevent negative values, which occur when the mean is not 0.5.
1237 const double min = double(min_percent) / 100.0;
1238 const double limit = raw_limit - _dwl_adjustment + min;
1239 return MAX2(limit, 0.0);
1240 }
1241
1242 ParallelCompactData::RegionData*
1243 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1244 const RegionData* end)
1245 {
1246 const size_t region_size = ParallelCompactData::RegionSize;
1247 ParallelCompactData& sd = summary_data();
1248 size_t left = sd.region(beg);
1249 size_t right = end > beg ? sd.region(end) - 1 : left;
1250
1251 // Binary search.
1252 while (left < right) {
1253 // Equivalent to (left + right) / 2, but does not overflow.
1254 const size_t middle = left + (right - left) / 2;
1255 RegionData* const middle_ptr = sd.region(middle);
1256 HeapWord* const dest = middle_ptr->destination();
1257 HeapWord* const addr = sd.region_to_addr(middle);
1258 assert(dest != NULL, "sanity");
1259 assert(dest <= addr, "must move left");
1260
1261 if (middle > left && dest < addr) {
1262 right = middle - 1;
1263 } else if (middle < right && middle_ptr->data_size() == region_size) {
1264 left = middle + 1;
1265 } else {
1266 return middle_ptr;
1267 }
1268 }
1269 return sd.region(left);
1270 }
1271
1272 ParallelCompactData::RegionData*
1273 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1274 const RegionData* end,
1275 size_t dead_words)
1276 {
1277 ParallelCompactData& sd = summary_data();
1278 size_t left = sd.region(beg);
1279 size_t right = end > beg ? sd.region(end) - 1 : left;
1280
1281 // Binary search.
1282 while (left < right) {
1283 // Equivalent to (left + right) / 2, but does not overflow.
1284 const size_t middle = left + (right - left) / 2;
1285 RegionData* const middle_ptr = sd.region(middle);
1286 HeapWord* const dest = middle_ptr->destination();
1287 HeapWord* const addr = sd.region_to_addr(middle);
1288 assert(dest != NULL, "sanity");
1289 assert(dest <= addr, "must move left");
1290
1291 const size_t dead_to_left = pointer_delta(addr, dest);
1292 if (middle > left && dead_to_left > dead_words) {
1293 right = middle - 1;
1294 } else if (middle < right && dead_to_left < dead_words) {
1295 left = middle + 1;
1296 } else {
1297 return middle_ptr;
1298 }
1299 }
1300 return sd.region(left);
1301 }
1302
1303 // The result is valid during the summary phase, after the initial summarization
1304 // of each space into itself, and before final summarization.
1305 inline double
1306 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1307 HeapWord* const bottom,
1308 HeapWord* const top,
1309 HeapWord* const new_top)
1310 {
1311 ParallelCompactData& sd = summary_data();
1312
1313 assert(cp != NULL, "sanity");
1314 assert(bottom != NULL, "sanity");
1315 assert(top != NULL, "sanity");
1316 assert(new_top != NULL, "sanity");
1317 assert(top >= new_top, "summary data problem?");
1318 assert(new_top > bottom, "space is empty; should not be here");
1319 assert(new_top >= cp->destination(), "sanity");
1320 assert(top >= sd.region_to_addr(cp), "sanity");
1321
1322 HeapWord* const destination = cp->destination();
1323 const size_t dense_prefix_live = pointer_delta(destination, bottom);
1324 const size_t compacted_region_live = pointer_delta(new_top, destination);
1325 const size_t compacted_region_used = pointer_delta(top,
1326 sd.region_to_addr(cp));
1327 const size_t reclaimable = compacted_region_used - compacted_region_live;
1328
1329 const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1330 return double(reclaimable) / divisor;
1331 }
1332
1333 // Return the address of the end of the dense prefix, a.k.a. the start of the
1334 // compacted region. The address is always on a region boundary.
1335 //
1336 // Completely full regions at the left are skipped, since no compaction can
1337 // occur in those regions. Then the maximum amount of dead wood to allow is
1338 // computed, based on the density (amount live / capacity) of the generation;
1339 // the region with approximately that amount of dead space to the left is
1340 // identified as the limit region. Regions between the last completely full
1341 // region and the limit region are scanned and the one that has the best
1342 // (maximum) reclaimed_ratio() is selected.
1343 HeapWord*
1344 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1345 bool maximum_compaction)
1346 {
1347 if (ParallelOldGCSplitALot) {
1348 if (_space_info[id].dense_prefix() != _space_info[id].space()->bottom()) {
1349 // The value was chosen to provoke splitting a young gen space; use it.
1350 return _space_info[id].dense_prefix();
1351 }
1352 }
1353
1354 const size_t region_size = ParallelCompactData::RegionSize;
1355 const ParallelCompactData& sd = summary_data();
1356
1357 const MutableSpace* const space = _space_info[id].space();
1358 HeapWord* const top = space->top();
1359 HeapWord* const top_aligned_up = sd.region_align_up(top);
1360 HeapWord* const new_top = _space_info[id].new_top();
1361 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1362 HeapWord* const bottom = space->bottom();
1363 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1364 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1365 const RegionData* const new_top_cp =
1366 sd.addr_to_region_ptr(new_top_aligned_up);
1367
1368 // Skip full regions at the beginning of the space--they are necessarily part
1369 // of the dense prefix.
1370 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1371 assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1372 space->is_empty(), "no dead space allowed to the left");
1373 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1374 "region must have dead space");
1375
1376 // The gc number is saved whenever a maximum compaction is done, and used to
1377 // determine when the maximum compaction interval has expired. This avoids
1378 // successive max compactions for different reasons.
1379 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1380 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1381 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1382 total_invocations() == HeapFirstMaximumCompactionCount;
1383 if (maximum_compaction || full_cp == top_cp || interval_ended) {
1384 _maximum_compaction_gc_num = total_invocations();
1385 return sd.region_to_addr(full_cp);
1386 }
1387
1388 const size_t space_live = pointer_delta(new_top, bottom);
1389 const size_t space_used = space->used_in_words();
1390 const size_t space_capacity = space->capacity_in_words();
1391
1392 const double density = double(space_live) / double(space_capacity);
1393 const size_t min_percent_free = MarkSweepDeadRatio;
1394 const double limiter = dead_wood_limiter(density, min_percent_free);
1395 const size_t dead_wood_max = space_used - space_live;
1396 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1397 dead_wood_max);
1398
1399 if (TraceParallelOldGCDensePrefix) {
1400 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1401 "space_cap=" SIZE_FORMAT,
1402 space_live, space_used,
1403 space_capacity);
1404 tty->print_cr("dead_wood_limiter(%6.4f, %d)=%6.4f "
1405 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1406 density, min_percent_free, limiter,
1407 dead_wood_max, dead_wood_limit);
1408 }
1409
1410 // Locate the region with the desired amount of dead space to the left.
1411 const RegionData* const limit_cp =
1412 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1413
1414 // Scan from the first region with dead space to the limit region and find the
1415 // one with the best (largest) reclaimed ratio.
1416 double best_ratio = 0.0;
1417 const RegionData* best_cp = full_cp;
1418 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1419 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1420 if (tmp_ratio > best_ratio) {
1421 best_cp = cp;
1422 best_ratio = tmp_ratio;
1423 }
1424 }
1425
1426 #if 0
1427 // Something to consider: if the region with the best ratio is 'close to' the
1428 // first region w/free space, choose the first region with free space
1429 // ("first-free"). The first-free region is usually near the start of the
1430 // heap, which means we are copying most of the heap already, so copy a bit
1431 // more to get complete compaction.
1432 if (pointer_delta(best_cp, full_cp, sizeof(RegionData)) < 4) {
1433 _maximum_compaction_gc_num = total_invocations();
1434 best_cp = full_cp;
1435 }
1436 #endif // #if 0
1437
1438 return sd.region_to_addr(best_cp);
1439 }
1440
1441 #ifndef PRODUCT
1442 void
1443 PSParallelCompact::fill_with_live_objects(SpaceId id, HeapWord* const start,
1444 size_t words)
1445 {
1446 if (TraceParallelOldGCSummaryPhase) {
1447 tty->print_cr("fill_with_live_objects [" PTR_FORMAT " " PTR_FORMAT ") "
1448 SIZE_FORMAT, start, start + words, words);
1449 }
1450
1451 ObjectStartArray* const start_array = _space_info[id].start_array();
1452 CollectedHeap::fill_with_objects(start, words);
1453 for (HeapWord* p = start; p < start + words; p += oop(p)->size()) {
1454 _mark_bitmap.mark_obj(p, words);
1455 _summary_data.add_obj(p, words);
1456 start_array->allocate_block(p);
1457 }
1458 }
1459
1460 void
1461 PSParallelCompact::summarize_new_objects(SpaceId id, HeapWord* start)
1462 {
1463 ParallelCompactData& sd = summary_data();
1464 MutableSpace* space = _space_info[id].space();
1465
1466 // Find the source and destination start addresses.
1467 HeapWord* const src_addr = sd.region_align_down(start);
1468 HeapWord* dst_addr;
1469 if (src_addr < start) {
1470 dst_addr = sd.addr_to_region_ptr(src_addr)->destination();
1471 } else if (src_addr > space->bottom()) {
1472 // The start (the original top() value) is aligned to a region boundary so
1473 // the associated region does not have a destination. Compute the
1474 // destination from the previous region.
1475 RegionData* const cp = sd.addr_to_region_ptr(src_addr) - 1;
1476 dst_addr = cp->destination() + cp->data_size();
1477 } else {
1478 // Filling the entire space.
1479 dst_addr = space->bottom();
1480 }
1481 assert(dst_addr != NULL, "sanity");
1482
1483 // Update the summary data.
1484 bool result = _summary_data.summarize(_space_info[id].split_info(),
1485 src_addr, space->top(), NULL,
1486 dst_addr, space->end(),
1487 _space_info[id].new_top_addr());
1488 assert(result, "should not fail: bad filler object size");
1489 }
1490
1491 void
1492 PSParallelCompact::provoke_split_fill_survivor(SpaceId id)
1493 {
1494 if (total_invocations() % (ParallelOldGCSplitInterval * 3) != 0) {
1495 return;
1496 }
1497
1498 MutableSpace* const space = _space_info[id].space();
1499 if (space->is_empty()) {
1500 HeapWord* b = space->bottom();
1501 HeapWord* t = b + space->capacity_in_words() / 2;
1502 space->set_top(t);
1503 if (ZapUnusedHeapArea) {
1504 space->set_top_for_allocations();
1505 }
1506
1507 size_t min_size = CollectedHeap::min_fill_size();
1508 size_t obj_len = min_size;
1509 while (b + obj_len <= t) {
1510 CollectedHeap::fill_with_object(b, obj_len);
1511 mark_bitmap()->mark_obj(b, obj_len);
1512 summary_data().add_obj(b, obj_len);
1513 b += obj_len;
1514 obj_len = (obj_len & (min_size*3)) + min_size; // 8 16 24 32 8 16 24 32 ...
1515 }
1516 if (b < t) {
1517 // The loop didn't completely fill to t (top); adjust top downward.
1518 space->set_top(b);
1519 if (ZapUnusedHeapArea) {
1520 space->set_top_for_allocations();
1521 }
1522 }
1523
1524 HeapWord** nta = _space_info[id].new_top_addr();
1525 bool result = summary_data().summarize(_space_info[id].split_info(),
1526 space->bottom(), space->top(), NULL,
1527 space->bottom(), space->end(), nta);
1528 assert(result, "space must fit into itself");
1529 }
1530 }
1531
1532 void
1533 PSParallelCompact::provoke_split(bool & max_compaction)
1534 {
1535 if (total_invocations() % ParallelOldGCSplitInterval != 0) {
1536 return;
1537 }
1538
1539 const size_t region_size = ParallelCompactData::RegionSize;
1540 ParallelCompactData& sd = summary_data();
1541
1542 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1543 MutableSpace* const from_space = _space_info[from_space_id].space();
1544 const size_t eden_live = pointer_delta(eden_space->top(),
1545 _space_info[eden_space_id].new_top());
1546 const size_t from_live = pointer_delta(from_space->top(),
1547 _space_info[from_space_id].new_top());
1548
1549 const size_t min_fill_size = CollectedHeap::min_fill_size();
1550 const size_t eden_free = pointer_delta(eden_space->end(), eden_space->top());
1551 const size_t eden_fillable = eden_free >= min_fill_size ? eden_free : 0;
1552 const size_t from_free = pointer_delta(from_space->end(), from_space->top());
1553 const size_t from_fillable = from_free >= min_fill_size ? from_free : 0;
1554
1555 // Choose the space to split; need at least 2 regions live (or fillable).
1556 SpaceId id;
1557 MutableSpace* space;
1558 size_t live_words;
1559 size_t fill_words;
1560 if (eden_live + eden_fillable >= region_size * 2) {
1561 id = eden_space_id;
1562 space = eden_space;
1563 live_words = eden_live;
1564 fill_words = eden_fillable;
1565 } else if (from_live + from_fillable >= region_size * 2) {
1566 id = from_space_id;
1567 space = from_space;
1568 live_words = from_live;
1569 fill_words = from_fillable;
1570 } else {
1571 return; // Give up.
1572 }
1573 assert(fill_words == 0 || fill_words >= min_fill_size, "sanity");
1574
1575 if (live_words < region_size * 2) {
1576 // Fill from top() to end() w/live objects of mixed sizes.
1577 HeapWord* const fill_start = space->top();
1578 live_words += fill_words;
1579
1580 space->set_top(fill_start + fill_words);
1581 if (ZapUnusedHeapArea) {
1582 space->set_top_for_allocations();
1583 }
1584
1585 HeapWord* cur_addr = fill_start;
1586 while (fill_words > 0) {
1587 const size_t r = (size_t)os::random() % (region_size / 2) + min_fill_size;
1588 size_t cur_size = MIN2(align_object_size_(r), fill_words);
1589 if (fill_words - cur_size < min_fill_size) {
1590 cur_size = fill_words; // Avoid leaving a fragment too small to fill.
1591 }
1592
1593 CollectedHeap::fill_with_object(cur_addr, cur_size);
1594 mark_bitmap()->mark_obj(cur_addr, cur_size);
1595 sd.add_obj(cur_addr, cur_size);
1596
1597 cur_addr += cur_size;
1598 fill_words -= cur_size;
1599 }
1600
1601 summarize_new_objects(id, fill_start);
1602 }
1603
1604 max_compaction = false;
1605
1606 // Manipulate the old gen so that it has room for about half of the live data
1607 // in the target young gen space (live_words / 2).
1608 id = old_space_id;
1609 space = _space_info[id].space();
1610 const size_t free_at_end = space->free_in_words();
1611 const size_t free_target = align_object_size(live_words / 2);
1612 const size_t dead = pointer_delta(space->top(), _space_info[id].new_top());
1613
1614 if (free_at_end >= free_target + min_fill_size) {
1615 // Fill space above top() and set the dense prefix so everything survives.
1616 HeapWord* const fill_start = space->top();
1617 const size_t fill_size = free_at_end - free_target;
1618 space->set_top(space->top() + fill_size);
1619 if (ZapUnusedHeapArea) {
1620 space->set_top_for_allocations();
1621 }
1622 fill_with_live_objects(id, fill_start, fill_size);
1623 summarize_new_objects(id, fill_start);
1624 _space_info[id].set_dense_prefix(sd.region_align_down(space->top()));
1625 } else if (dead + free_at_end > free_target) {
1626 // Find a dense prefix that makes the right amount of space available.
1627 HeapWord* cur = sd.region_align_down(space->top());
1628 HeapWord* cur_destination = sd.addr_to_region_ptr(cur)->destination();
1629 size_t dead_to_right = pointer_delta(space->end(), cur_destination);
1630 while (dead_to_right < free_target) {
1631 cur -= region_size;
1632 cur_destination = sd.addr_to_region_ptr(cur)->destination();
1633 dead_to_right = pointer_delta(space->end(), cur_destination);
1634 }
1635 _space_info[id].set_dense_prefix(cur);
1636 }
1637 }
1638 #endif // #ifndef PRODUCT
1639
1640 void PSParallelCompact::summarize_spaces_quick()
1641 {
1642 for (unsigned int i = 0; i < last_space_id; ++i) {
1643 const MutableSpace* space = _space_info[i].space();
1644 HeapWord** nta = _space_info[i].new_top_addr();
1645 bool result = _summary_data.summarize(_space_info[i].split_info(),
1646 space->bottom(), space->top(), NULL,
1647 space->bottom(), space->end(), nta);
1648 assert(result, "space must fit into itself");
1649 _space_info[i].set_dense_prefix(space->bottom());
1650 }
1651
1652 #ifndef PRODUCT
1653 if (ParallelOldGCSplitALot) {
1654 provoke_split_fill_survivor(to_space_id);
1655 }
1656 #endif // #ifndef PRODUCT
1657 }
1658
1659 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1660 {
1661 HeapWord* const dense_prefix_end = dense_prefix(id);
1662 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1663 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1664 if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1665 // Only enough dead space is filled so that any remaining dead space to the
1666 // left is larger than the minimum filler object. (The remainder is filled
1667 // during the copy/update phase.)
1668 //
1669 // The size of the dead space to the right of the boundary is not a
1670 // concern, since compaction will be able to use whatever space is
1671 // available.
1672 //
1673 // Here '||' is the boundary, 'x' represents a don't care bit and a box
1674 // surrounds the space to be filled with an object.
1675 //
1676 // In the 32-bit VM, each bit represents two 32-bit words:
1677 // +---+
1678 // a) beg_bits: ... x x x | 0 | || 0 x x ...
1679 // end_bits: ... x x x | 0 | || 0 x x ...
1680 // +---+
1681 //
1682 // In the 64-bit VM, each bit represents one 64-bit word:
1683 // +------------+
1684 // b) beg_bits: ... x x x | 0 || 0 | x x ...
1685 // end_bits: ... x x 1 | 0 || 0 | x x ...
1686 // +------------+
1687 // +-------+
1688 // c) beg_bits: ... x x | 0 0 | || 0 x x ...
1689 // end_bits: ... x 1 | 0 0 | || 0 x x ...
1690 // +-------+
1691 // +-----------+
1692 // d) beg_bits: ... x | 0 0 0 | || 0 x x ...
1693 // end_bits: ... 1 | 0 0 0 | || 0 x x ...
1694 // +-----------+
1695 // +-------+
1696 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ...
1697 // end_bits: ... 0 0 | 0 0 | || 0 x x ...
1698 // +-------+
1699
1700 // Initially assume case a, c or e will apply.
1701 size_t obj_len = CollectedHeap::min_fill_size();
1702 HeapWord* obj_beg = dense_prefix_end - obj_len;
1703
1704 #ifdef _LP64
1705 if (MinObjAlignment > 1) { // object alignment > heap word size
1706 // Cases a, c or e.
1707 } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1708 // Case b above.
1709 obj_beg = dense_prefix_end - 1;
1710 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1711 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1712 // Case d above.
1713 obj_beg = dense_prefix_end - 3;
1714 obj_len = 3;
1715 }
1716 #endif // #ifdef _LP64
1717
1718 CollectedHeap::fill_with_object(obj_beg, obj_len);
1719 _mark_bitmap.mark_obj(obj_beg, obj_len);
1720 _summary_data.add_obj(obj_beg, obj_len);
1721 assert(start_array(id) != NULL, "sanity");
1722 start_array(id)->allocate_block(obj_beg);
1723 }
1724 }
1725
1726 void
1727 PSParallelCompact::clear_source_region(HeapWord* beg_addr, HeapWord* end_addr)
1728 {
1729 RegionData* const beg_ptr = _summary_data.addr_to_region_ptr(beg_addr);
1730 HeapWord* const end_aligned_up = _summary_data.region_align_up(end_addr);
1731 RegionData* const end_ptr = _summary_data.addr_to_region_ptr(end_aligned_up);
1732 for (RegionData* cur = beg_ptr; cur < end_ptr; ++cur) {
1733 cur->set_source_region(0);
1734 }
1735 }
1736
1737 void
1738 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1739 {
1740 assert(id < last_space_id, "id out of range");
1741 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom() ||
1742 ParallelOldGCSplitALot && id == old_space_id,
1743 "should have been reset in summarize_spaces_quick()");
1744
1745 const MutableSpace* space = _space_info[id].space();
1746 if (_space_info[id].new_top() != space->bottom()) {
1747 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1748 _space_info[id].set_dense_prefix(dense_prefix_end);
1749
1750 #ifndef PRODUCT
1751 if (TraceParallelOldGCDensePrefix) {
1752 print_dense_prefix_stats("ratio", id, maximum_compaction,
1753 dense_prefix_end);
1754 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1755 print_dense_prefix_stats("density", id, maximum_compaction, addr);
1756 }
1757 #endif // #ifndef PRODUCT
1758
1759 // Recompute the summary data, taking into account the dense prefix. If
1760 // every last byte will be reclaimed, then the existing summary data which
1761 // compacts everything can be left in place.
1762 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1763 // If dead space crosses the dense prefix boundary, it is (at least
1764 // partially) filled with a dummy object, marked live and added to the
1765 // summary data. This simplifies the copy/update phase and must be done
1766 // before the final locations of objects are determined, to prevent
1767 // leaving a fragment of dead space that is too small to fill.
1768 fill_dense_prefix_end(id);
1769
1770 // Compute the destination of each Region, and thus each object.
1771 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1772 _summary_data.summarize(_space_info[id].split_info(),
1773 dense_prefix_end, space->top(), NULL,
1774 dense_prefix_end, space->end(),
1775 _space_info[id].new_top_addr());
1776 }
1777 }
1778
1779 if (TraceParallelOldGCSummaryPhase) {
1780 const size_t region_size = ParallelCompactData::RegionSize;
1781 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1782 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1783 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1784 HeapWord* const new_top = _space_info[id].new_top();
1785 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1786 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1787 tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1788 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1789 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1790 id, space->capacity_in_words(), dense_prefix_end,
1791 dp_region, dp_words / region_size,
1792 cr_words / region_size, new_top);
1793 }
1794 }
1795
1796 #ifndef PRODUCT
1797 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1798 HeapWord* dst_beg, HeapWord* dst_end,
1799 SpaceId src_space_id,
1800 HeapWord* src_beg, HeapWord* src_end)
1801 {
1802 if (TraceParallelOldGCSummaryPhase) {
1803 tty->print_cr("summarizing %d [%s] into %d [%s]: "
1804 "src=" PTR_FORMAT "-" PTR_FORMAT " "
1805 SIZE_FORMAT "-" SIZE_FORMAT " "
1806 "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1807 SIZE_FORMAT "-" SIZE_FORMAT,
1808 src_space_id, space_names[src_space_id],
1809 dst_space_id, space_names[dst_space_id],
1810 src_beg, src_end,
1811 _summary_data.addr_to_region_idx(src_beg),
1812 _summary_data.addr_to_region_idx(src_end),
1813 dst_beg, dst_end,
1814 _summary_data.addr_to_region_idx(dst_beg),
1815 _summary_data.addr_to_region_idx(dst_end));
1816 }
1817 }
1818 #endif // #ifndef PRODUCT
1819
1820 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1821 bool maximum_compaction)
1822 {
1823 GCTraceTime tm("summary phase", print_phases(), true, &_gc_timer);
1824 // trace("2");
1825
1826 #ifdef ASSERT
1827 if (TraceParallelOldGCMarkingPhase) {
1828 tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1829 "add_obj_bytes=" SIZE_FORMAT,
1830 add_obj_count, add_obj_size * HeapWordSize);
1831 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1832 "mark_bitmap_bytes=" SIZE_FORMAT,
1833 mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1834 }
1835 #endif // #ifdef ASSERT
1836
1837 // Quick summarization of each space into itself, to see how much is live.
1838 summarize_spaces_quick();
1839
1840 if (TraceParallelOldGCSummaryPhase) {
1841 tty->print_cr("summary_phase: after summarizing each space to self");
1842 Universe::print();
1843 NOT_PRODUCT(print_region_ranges());
1844 if (Verbose) {
1845 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1846 }
1847 }
1848
1849 // The amount of live data that will end up in old space (assuming it fits).
1850 size_t old_space_total_live = 0;
1851 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1852 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1853 _space_info[id].space()->bottom());
1854 }
1855
1856 MutableSpace* const old_space = _space_info[old_space_id].space();
1857 const size_t old_capacity = old_space->capacity_in_words();
1858 if (old_space_total_live > old_capacity) {
1859 // XXX - should also try to expand
1860 maximum_compaction = true;
1861 }
1862 #ifndef PRODUCT
1863 if (ParallelOldGCSplitALot && old_space_total_live < old_capacity) {
1864 provoke_split(maximum_compaction);
1865 }
1866 #endif // #ifndef PRODUCT
1867
1868 // Old generations.
1869 summarize_space(old_space_id, maximum_compaction);
1870
1871 // Summarize the remaining spaces in the young gen. The initial target space
1872 // is the old gen. If a space does not fit entirely into the target, then the
1873 // remainder is compacted into the space itself and that space becomes the new
1874 // target.
1875 SpaceId dst_space_id = old_space_id;
1876 HeapWord* dst_space_end = old_space->end();
1877 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1878 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1879 const MutableSpace* space = _space_info[id].space();
1880 const size_t live = pointer_delta(_space_info[id].new_top(),
1881 space->bottom());
1882 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1883
1884 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1885 SpaceId(id), space->bottom(), space->top());)
1886 if (live > 0 && live <= available) {
1887 // All the live data will fit.
1888 bool done = _summary_data.summarize(_space_info[id].split_info(),
1889 space->bottom(), space->top(),
1890 NULL,
1891 *new_top_addr, dst_space_end,
1892 new_top_addr);
1893 assert(done, "space must fit into old gen");
1894
1895 // Reset the new_top value for the space.
1896 _space_info[id].set_new_top(space->bottom());
1897 } else if (live > 0) {
1898 // Attempt to fit part of the source space into the target space.
1899 HeapWord* next_src_addr = NULL;
1900 bool done = _summary_data.summarize(_space_info[id].split_info(),
1901 space->bottom(), space->top(),
1902 &next_src_addr,
1903 *new_top_addr, dst_space_end,
1904 new_top_addr);
1905 assert(!done, "space should not fit into old gen");
1906 assert(next_src_addr != NULL, "sanity");
1907
1908 // The source space becomes the new target, so the remainder is compacted
1909 // within the space itself.
1910 dst_space_id = SpaceId(id);
1911 dst_space_end = space->end();
1912 new_top_addr = _space_info[id].new_top_addr();
1913 NOT_PRODUCT(summary_phase_msg(dst_space_id,
1914 space->bottom(), dst_space_end,
1915 SpaceId(id), next_src_addr, space->top());)
1916 done = _summary_data.summarize(_space_info[id].split_info(),
1917 next_src_addr, space->top(),
1918 NULL,
1919 space->bottom(), dst_space_end,
1920 new_top_addr);
1921 assert(done, "space must fit when compacted into itself");
1922 assert(*new_top_addr <= space->top(), "usage should not grow");
1923 }
1924 }
1925
1926 if (TraceParallelOldGCSummaryPhase) {
1927 tty->print_cr("summary_phase: after final summarization");
1928 Universe::print();
1929 NOT_PRODUCT(print_region_ranges());
1930 if (Verbose) {
1931 NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info));
1932 }
1933 }
1934 }
1935
1936 // This method should contain all heap-specific policy for invoking a full
1937 // collection. invoke_no_policy() will only attempt to compact the heap; it
1938 // will do nothing further. If we need to bail out for policy reasons, scavenge
1939 // before full gc, or any other specialized behavior, it needs to be added here.
1940 //
1941 // Note that this method should only be called from the vm_thread while at a
1942 // safepoint.
1943 //
1944 // Note that the all_soft_refs_clear flag in the collector policy
1945 // may be true because this method can be called without intervening
1946 // activity. For example when the heap space is tight and full measure
1947 // are being taken to free space.
1948 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1949 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1950 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1951 "should be in vm thread");
1952
1953 ParallelScavengeHeap* heap = gc_heap();
1954 GCCause::Cause gc_cause = heap->gc_cause();
1955 assert(!heap->is_gc_active(), "not reentrant");
1956
1957 PSAdaptiveSizePolicy* policy = heap->size_policy();
1958 IsGCActiveMark mark;
1959
1960 if (ScavengeBeforeFullGC) {
1961 PSScavenge::invoke_no_policy();
1962 }
1963
1964 const bool clear_all_soft_refs =
1965 heap->collector_policy()->should_clear_all_soft_refs();
1966
1967 PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1968 maximum_heap_compaction);
1969 }
1970
1971 bool ParallelCompactData::region_contains(size_t region_index, HeapWord* addr) {
1972 size_t addr_region_index = addr_to_region_idx(addr);
1973 return region_index == addr_region_index;
1974 }
1975
1976 // This method contains no policy. You should probably
1977 // be calling invoke() instead.
1978 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1979 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1980 assert(ref_processor() != NULL, "Sanity");
1981
1982 if (GC_locker::check_active_before_gc()) {
1983 return false;
1984 }
1985
1986 ParallelScavengeHeap* heap = gc_heap();
1987
1988 _gc_timer.register_gc_start(os::elapsed_counter());
1989 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
1990
1991 TimeStamp marking_start;
1992 TimeStamp compaction_start;
1993 TimeStamp collection_exit;
1994
1995 GCCause::Cause gc_cause = heap->gc_cause();
1996 PSYoungGen* young_gen = heap->young_gen();
1997 PSOldGen* old_gen = heap->old_gen();
1998 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1999
2000 // The scope of casr should end after code that can change
2001 // CollectorPolicy::_should_clear_all_soft_refs.
2002 ClearedAllSoftRefs casr(maximum_heap_compaction,
2003 heap->collector_policy());
2004
2005 if (ZapUnusedHeapArea) {
2006 // Save information needed to minimize mangling
2007 heap->record_gen_tops_before_GC();
2008 }
2009
2010 heap->pre_full_gc_dump(&_gc_timer);
2011
2012 _print_phases = PrintGCDetails && PrintParallelOldGCPhaseTimes;
2013
2014 // Make sure data structures are sane, make the heap parsable, and do other
2015 // miscellaneous bookkeeping.
2016 PreGCValues pre_gc_values;
2017 pre_compact(&pre_gc_values);
2018
2019 // Get the compaction manager reserved for the VM thread.
2020 ParCompactionManager* const vmthread_cm =
2021 ParCompactionManager::manager_array(gc_task_manager()->workers());
2022
2023 // Place after pre_compact() where the number of invocations is incremented.
2024 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
2025
2026 {
2027 ResourceMark rm;
2028 HandleMark hm;
2029
2030 // Set the number of GC threads to be used in this collection
2031 gc_task_manager()->set_active_gang();
2032 gc_task_manager()->task_idle_workers();
2033 heap->set_par_threads(gc_task_manager()->active_workers());
2034
2035 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2036 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2037 GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL);
2038 TraceCollectorStats tcs(counters());
2039 TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
2040
2041 if (TraceGen1Time) accumulated_time()->start();
2042
2043 // Let the size policy know we're starting
2044 size_policy->major_collection_begin();
2045
2046 CodeCache::gc_prologue();
2047 Threads::gc_prologue();
2048
2049 COMPILER2_PRESENT(DerivedPointerTable::clear());
2050
2051 ref_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
2052 ref_processor()->setup_policy(maximum_heap_compaction);
2053
2054 bool marked_for_unloading = false;
2055
2056 marking_start.update();
2057 marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer);
2058
2059 bool max_on_system_gc = UseMaximumCompactionOnSystemGC
2060 && gc_cause == GCCause::_java_lang_system_gc;
2061 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
2062
2063 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
2064 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
2065
2066 // adjust_roots() updates Universe::_intArrayKlassObj which is
2067 // needed by the compaction for filling holes in the dense prefix.
2068 adjust_roots();
2069
2070 compaction_start.update();
2071 compact();
2072
2073 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
2074 // done before resizing.
2075 post_compact();
2076
2077 // Let the size policy know we're done
2078 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
2079
2080 if (UseAdaptiveSizePolicy) {
2081 if (PrintAdaptiveSizePolicy) {
2082 gclog_or_tty->print("AdaptiveSizeStart: ");
2083 gclog_or_tty->stamp();
2084 gclog_or_tty->print_cr(" collection: %d ",
2085 heap->total_collections());
2086 if (Verbose) {
2087 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d",
2088 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
2089 }
2090 }
2091
2092 // Don't check if the size_policy is ready here. Let
2093 // the size_policy check that internally.
2094 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
2095 ((gc_cause != GCCause::_java_lang_system_gc) ||
2096 UseAdaptiveSizePolicyWithSystemGC)) {
2097 // Calculate optimal free space amounts
2098 assert(young_gen->max_size() >
2099 young_gen->from_space()->capacity_in_bytes() +
2100 young_gen->to_space()->capacity_in_bytes(),
2101 "Sizes of space in young gen are out-of-bounds");
2102
2103 size_t young_live = young_gen->used_in_bytes();
2104 size_t eden_live = young_gen->eden_space()->used_in_bytes();
2105 size_t old_live = old_gen->used_in_bytes();
2106 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
2107 size_t max_old_gen_size = old_gen->max_gen_size();
2108 size_t max_eden_size = young_gen->max_size() -
2109 young_gen->from_space()->capacity_in_bytes() -
2110 young_gen->to_space()->capacity_in_bytes();
2111
2112 // Used for diagnostics
2113 size_policy->clear_generation_free_space_flags();
2114
2115 size_policy->compute_generations_free_space(young_live,
2116 eden_live,
2117 old_live,
2118 cur_eden,
2119 max_old_gen_size,
2120 max_eden_size,
2121 true /* full gc*/);
2122
2123 size_policy->check_gc_overhead_limit(young_live,
2124 eden_live,
2125 max_old_gen_size,
2126 max_eden_size,
2127 true /* full gc*/,
2128 gc_cause,
2129 heap->collector_policy());
2130
2131 size_policy->decay_supplemental_growth(true /* full gc*/);
2132
2133 heap->resize_old_gen(
2134 size_policy->calculated_old_free_size_in_bytes());
2135
2136 // Don't resize the young generation at an major collection. A
2137 // desired young generation size may have been calculated but
2138 // resizing the young generation complicates the code because the
2139 // resizing of the old generation may have moved the boundary
2140 // between the young generation and the old generation. Let the
2141 // young generation resizing happen at the minor collections.
2142 }
2143 if (PrintAdaptiveSizePolicy) {
2144 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
2145 heap->total_collections());
2146 }
2147 }
2148
2149 if (UsePerfData) {
2150 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
2151 counters->update_counters();
2152 counters->update_old_capacity(old_gen->capacity_in_bytes());
2153 counters->update_young_capacity(young_gen->capacity_in_bytes());
2154 }
2155
2156 heap->resize_all_tlabs();
2157
2158 // Resize the metaspace capactiy after a collection
2159 MetaspaceGC::compute_new_size();
2160
2161 if (TraceGen1Time) accumulated_time()->stop();
2162
2163 if (PrintGC) {
2164 if (PrintGCDetails) {
2165 // No GC timestamp here. This is after GC so it would be confusing.
2166 young_gen->print_used_change(pre_gc_values.young_gen_used());
2167 old_gen->print_used_change(pre_gc_values.old_gen_used());
2168 heap->print_heap_change(pre_gc_values.heap_used());
2169 MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used());
2170 } else {
2171 heap->print_heap_change(pre_gc_values.heap_used());
2172 }
2173 }
2174
2175 // Track memory usage and detect low memory
2176 MemoryService::track_memory_usage();
2177 heap->update_counters();
2178 gc_task_manager()->release_idle_workers();
2179 }
2180
2181 #ifdef ASSERT
2182 for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
2183 ParCompactionManager* const cm =
2184 ParCompactionManager::manager_array(int(i));
2185 assert(cm->marking_stack()->is_empty(), "should be empty");
2186 assert(ParCompactionManager::region_list(int(i))->is_empty(), "should be empty");
2187 }
2188 #endif // ASSERT
2189
2190 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
2191 HandleMark hm; // Discard invalid handles created during verification
2192 Universe::verify(" VerifyAfterGC:");
2193 }
2194
2195 // Re-verify object start arrays
2196 if (VerifyObjectStartArray &&
2197 VerifyAfterGC) {
2198 old_gen->verify_object_start_array();
2199 }
2200
2201 if (ZapUnusedHeapArea) {
2202 old_gen->object_space()->check_mangled_unused_area_complete();
2203 }
2204
2205 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
2206
2207 collection_exit.update();
2208
2209 heap->print_heap_after_gc();
2210 heap->trace_heap_after_gc(&_gc_tracer);
2211
2212 if (PrintGCTaskTimeStamps) {
2213 gclog_or_tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " "
2214 INT64_FORMAT,
2215 marking_start.ticks(), compaction_start.ticks(),
2216 collection_exit.ticks());
2217 gc_task_manager()->print_task_time_stamps();
2218 }
2219
2220 heap->post_full_gc_dump(&_gc_timer);
2221
2222 #ifdef TRACESPINNING
2223 ParallelTaskTerminator::print_termination_counts();
2224 #endif
2225
2226 _gc_timer.register_gc_end(os::elapsed_counter());
2227
2228 _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
2229 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
2230
2231 return true;
2232 }
2233
2234 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
2235 PSYoungGen* young_gen,
2236 PSOldGen* old_gen) {
2237 MutableSpace* const eden_space = young_gen->eden_space();
2238 assert(!eden_space->is_empty(), "eden must be non-empty");
2239 assert(young_gen->virtual_space()->alignment() ==
2240 old_gen->virtual_space()->alignment(), "alignments do not match");
2241
2242 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
2243 return false;
2244 }
2245
2246 // Both generations must be completely committed.
2247 if (young_gen->virtual_space()->uncommitted_size() != 0) {
2248 return false;
2249 }
2250 if (old_gen->virtual_space()->uncommitted_size() != 0) {
2251 return false;
2252 }
2253
2254 // Figure out how much to take from eden. Include the average amount promoted
2255 // in the total; otherwise the next young gen GC will simply bail out to a
2256 // full GC.
2257 const size_t alignment = old_gen->virtual_space()->alignment();
2258 const size_t eden_used = eden_space->used_in_bytes();
2259 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
2260 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
2261 const size_t eden_capacity = eden_space->capacity_in_bytes();
2262
2263 if (absorb_size >= eden_capacity) {
2264 return false; // Must leave some space in eden.
2265 }
2266
2267 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2268 if (new_young_size < young_gen->min_gen_size()) {
2269 return false; // Respect young gen minimum size.
2270 }
2271
2272 if (TraceAdaptiveGCBoundary && Verbose) {
2273 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
2274 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2275 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2276 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2277 absorb_size / K,
2278 eden_capacity / K, (eden_capacity - absorb_size) / K,
2279 young_gen->from_space()->used_in_bytes() / K,
2280 young_gen->to_space()->used_in_bytes() / K,
2281 young_gen->capacity_in_bytes() / K, new_young_size / K);
2282 }
2283
2284 // Fill the unused part of the old gen.
2285 MutableSpace* const old_space = old_gen->object_space();
2286 HeapWord* const unused_start = old_space->top();
2287 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2288
2289 if (unused_words > 0) {
2290 if (unused_words < CollectedHeap::min_fill_size()) {
2291 return false; // If the old gen cannot be filled, must give up.
2292 }
2293 CollectedHeap::fill_with_objects(unused_start, unused_words);
2294 }
2295
2296 // Take the live data from eden and set both top and end in the old gen to
2297 // eden top. (Need to set end because reset_after_change() mangles the region
2298 // from end to virtual_space->high() in debug builds).
2299 HeapWord* const new_top = eden_space->top();
2300 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2301 absorb_size);
2302 young_gen->reset_after_change();
2303 old_space->set_top(new_top);
2304 old_space->set_end(new_top);
2305 old_gen->reset_after_change();
2306
2307 // Update the object start array for the filler object and the data from eden.
2308 ObjectStartArray* const start_array = old_gen->start_array();
2309 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2310 start_array->allocate_block(p);
2311 }
2312
2313 // Could update the promoted average here, but it is not typically updated at
2314 // full GCs and the value to use is unclear. Something like
2315 //
2316 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2317
2318 size_policy->set_bytes_absorbed_from_eden(absorb_size);
2319 return true;
2320 }
2321
2322 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2323 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2324 "shouldn't return NULL");
2325 return ParallelScavengeHeap::gc_task_manager();
2326 }
2327
2328 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2329 bool maximum_heap_compaction,
2330 ParallelOldTracer *gc_tracer) {
2331 // Recursively traverse all live objects and mark them
2332 GCTraceTime tm("marking phase", print_phases(), true, &_gc_timer);
2333
2334 ParallelScavengeHeap* heap = gc_heap();
2335 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2336 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2337 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2338 ParallelTaskTerminator terminator(active_gc_threads, qset);
2339
2340 PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
2341 PSParallelCompact::FollowStackClosure follow_stack_closure(cm);
2342
2343 // Need new claim bits before marking starts.
2344 ClassLoaderDataGraph::clear_claimed_marks();
2345
2346 {
2347 GCTraceTime tm_m("par mark", print_phases(), true, &_gc_timer);
2348
2349 ParallelScavengeHeap::ParStrongRootsScope psrs;
2350
2351 GCTaskQueue* q = GCTaskQueue::create();
2352
2353 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2354 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2355 // We scan the thread roots in parallel
2356 Threads::create_thread_roots_marking_tasks(q);
2357 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2358 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
2359 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2360 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2361 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data));
2362 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2363 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2364
2365 if (active_gc_threads > 1) {
2366 for (uint j = 0; j < active_gc_threads; j++) {
2367 q->enqueue(new StealMarkingTask(&terminator));
2368 }
2369 }
2370
2371 gc_task_manager()->execute_and_wait(q);
2372 }
2373
2374 // Process reference objects found during marking
2375 {
2376 GCTraceTime tm_r("reference processing", print_phases(), true, &_gc_timer);
2377
2378 ReferenceProcessorStats stats;
2379 if (ref_processor()->processing_is_mt()) {
2380 RefProcTaskExecutor task_executor;
2381 stats = ref_processor()->process_discovered_references(
2382 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2383 &task_executor, &_gc_timer);
2384 } else {
2385 stats = ref_processor()->process_discovered_references(
2386 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
2387 &_gc_timer);
2388 }
2389
2390 gc_tracer->report_gc_reference_stats(stats);
2391 }
2392
2393 GCTraceTime tm_c("class unloading", print_phases(), true, &_gc_timer);
2394
2395 // This is the point where the entire marking should have completed.
2396 assert(cm->marking_stacks_empty(), "Marking should have completed");
2397
2398 // Follow system dictionary roots and unload classes.
2399 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
2400
2401 // Unload nmethods.
2402 CodeCache::do_unloading(is_alive_closure(), purged_class);
2403
2404 // Prune dead klasses from subklass/sibling/implementor lists.
2405 Klass::clean_weak_klass_links(is_alive_closure());
2406
2407 // Delete entries for dead interned strings.
2408 StringTable::unlink(is_alive_closure());
2409
2410 // Clean up unreferenced symbols in symbol table.
2411 SymbolTable::unlink();
2412 _gc_tracer.report_object_count_after_gc(is_alive_closure());
2413 }
2414
2415 void PSParallelCompact::follow_klass(ParCompactionManager* cm, Klass* klass) {
2416 ClassLoaderData* cld = klass->class_loader_data();
2417 // The actual processing of the klass is done when we
2418 // traverse the list of Klasses in the class loader data.
2419 PSParallelCompact::follow_class_loader(cm, cld);
2420 }
2421
2422 void PSParallelCompact::adjust_klass(ParCompactionManager* cm, Klass* klass) {
2423 ClassLoaderData* cld = klass->class_loader_data();
2424 // The actual processing of the klass is done when we
2425 // traverse the list of Klasses in the class loader data.
2426 PSParallelCompact::adjust_class_loader(cm, cld);
2427 }
2428
2429 void PSParallelCompact::follow_class_loader(ParCompactionManager* cm,
2430 ClassLoaderData* cld) {
2431 PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
2432 PSParallelCompact::FollowKlassClosure follow_klass_closure(&mark_and_push_closure);
2433
2434 cld->oops_do(&mark_and_push_closure, &follow_klass_closure, true);
2435 }
2436
2437 void PSParallelCompact::adjust_class_loader(ParCompactionManager* cm,
2438 ClassLoaderData* cld) {
2439 cld->oops_do(PSParallelCompact::adjust_pointer_closure(),
2440 PSParallelCompact::adjust_klass_closure(),
2441 true);
2442 }
2443
2444 // This should be moved to the shared markSweep code!
2445 class PSAlwaysTrueClosure: public BoolObjectClosure {
2446 public:
2447 bool do_object_b(oop p) { return true; }
2448 };
2449 static PSAlwaysTrueClosure always_true;
2450
2451 void PSParallelCompact::adjust_roots() {
2452 // Adjust the pointers to reflect the new locations
2453 GCTraceTime tm("adjust roots", print_phases(), true, &_gc_timer);
2454
2455 // Need new claim bits when tracing through and adjusting pointers.
2456 ClassLoaderDataGraph::clear_claimed_marks();
2457
2458 // General strong roots.
2459 Universe::oops_do(adjust_pointer_closure());
2460 JNIHandles::oops_do(adjust_pointer_closure()); // Global (strong) JNI handles
2461 CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
2462 Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
2463 ObjectSynchronizer::oops_do(adjust_pointer_closure());
2464 FlatProfiler::oops_do(adjust_pointer_closure());
2465 Management::oops_do(adjust_pointer_closure());
2466 JvmtiExport::oops_do(adjust_pointer_closure());
2467 // SO_AllClasses
2468 SystemDictionary::oops_do(adjust_pointer_closure());
2469 ClassLoaderDataGraph::oops_do(adjust_pointer_closure(), adjust_klass_closure(), true);
2470
2471 // Now adjust pointers in remaining weak roots. (All of which should
2472 // have been cleared if they pointed to non-surviving objects.)
2473 // Global (weak) JNI handles
2474 JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure());
2475
2476 CodeCache::oops_do(adjust_pointer_closure());
2477 StringTable::oops_do(adjust_pointer_closure());
2478 ref_processor()->weak_oops_do(adjust_pointer_closure());
2479 // Roots were visited so references into the young gen in roots
2480 // may have been scanned. Process them also.
2481 // Should the reference processor have a span that excludes
2482 // young gen objects?
2483 PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
2484 }
2485
2486 void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q,
2487 uint parallel_gc_threads)
2488 {
2489 GCTraceTime tm("drain task setup", print_phases(), true, &_gc_timer);
2490
2491 // Find the threads that are active
2492 unsigned int which = 0;
2493
2494 const uint task_count = MAX2(parallel_gc_threads, 1U);
2495 for (uint j = 0; j < task_count; j++) {
2496 q->enqueue(new DrainStacksCompactionTask(j));
2497 ParCompactionManager::verify_region_list_empty(j);
2498 // Set the region stacks variables to "no" region stack values
2499 // so that they will be recognized and needing a region stack
2500 // in the stealing tasks if they do not get one by executing
2501 // a draining stack.
2502 ParCompactionManager* cm = ParCompactionManager::manager_array(j);
2503 cm->set_region_stack(NULL);
2504 cm->set_region_stack_index((uint)max_uintx);
2505 }
2506 ParCompactionManager::reset_recycled_stack_index();
2507
2508 // Find all regions that are available (can be filled immediately) and
2509 // distribute them to the thread stacks. The iteration is done in reverse
2510 // order (high to low) so the regions will be removed in ascending order.
2511
2512 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2513
2514 size_t fillable_regions = 0; // A count for diagnostic purposes.
2515 // A region index which corresponds to the tasks created above.
2516 // "which" must be 0 <= which < task_count
2517
2518 which = 0;
2519 // id + 1 is used to test termination so unsigned can
2520 // be used with an old_space_id == 0.
2521 for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2522 SpaceInfo* const space_info = _space_info + id;
2523 MutableSpace* const space = space_info->space();
2524 HeapWord* const new_top = space_info->new_top();
2525
2526 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2527 const size_t end_region =
2528 sd.addr_to_region_idx(sd.region_align_up(new_top));
2529
2530 for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2531 if (sd.region(cur)->claim_unsafe()) {
2532 ParCompactionManager::region_list_push(which, cur);
2533
2534 if (TraceParallelOldGCCompactionPhase && Verbose) {
2535 const size_t count_mod_8 = fillable_regions & 7;
2536 if (count_mod_8 == 0) gclog_or_tty->print("fillable: ");
2537 gclog_or_tty->print(" " SIZE_FORMAT_W(7), cur);
2538 if (count_mod_8 == 7) gclog_or_tty->cr();
2539 }
2540
2541 NOT_PRODUCT(++fillable_regions;)
2542
2543 // Assign regions to tasks in round-robin fashion.
2544 if (++which == task_count) {
2545 assert(which <= parallel_gc_threads,
2546 "Inconsistent number of workers");
2547 which = 0;
2548 }
2549 }
2550 }
2551 }
2552
2553 if (TraceParallelOldGCCompactionPhase) {
2554 if (Verbose && (fillable_regions & 7) != 0) gclog_or_tty->cr();
2555 gclog_or_tty->print_cr("%u initially fillable regions", fillable_regions);
2556 }
2557 }
2558
2559 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2560
2561 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2562 uint parallel_gc_threads) {
2563 GCTraceTime tm("dense prefix task setup", print_phases(), true, &_gc_timer);
2564
2565 ParallelCompactData& sd = PSParallelCompact::summary_data();
2566
2567 // Iterate over all the spaces adding tasks for updating
2568 // regions in the dense prefix. Assume that 1 gc thread
2569 // will work on opening the gaps and the remaining gc threads
2570 // will work on the dense prefix.
2571 unsigned int space_id;
2572 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2573 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2574 const MutableSpace* const space = _space_info[space_id].space();
2575
2576 if (dense_prefix_end == space->bottom()) {
2577 // There is no dense prefix for this space.
2578 continue;
2579 }
2580
2581 // The dense prefix is before this region.
2582 size_t region_index_end_dense_prefix =
2583 sd.addr_to_region_idx(dense_prefix_end);
2584 RegionData* const dense_prefix_cp =
2585 sd.region(region_index_end_dense_prefix);
2586 assert(dense_prefix_end == space->end() ||
2587 dense_prefix_cp->available() ||
2588 dense_prefix_cp->claimed(),
2589 "The region after the dense prefix should always be ready to fill");
2590
2591 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2592
2593 // Is there dense prefix work?
2594 size_t total_dense_prefix_regions =
2595 region_index_end_dense_prefix - region_index_start;
2596 // How many regions of the dense prefix should be given to
2597 // each thread?
2598 if (total_dense_prefix_regions > 0) {
2599 uint tasks_for_dense_prefix = 1;
2600 if (total_dense_prefix_regions <=
2601 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2602 // Don't over partition. This assumes that
2603 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2604 // so there are not many regions to process.
2605 tasks_for_dense_prefix = parallel_gc_threads;
2606 } else {
2607 // Over partition
2608 tasks_for_dense_prefix = parallel_gc_threads *
2609 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2610 }
2611 size_t regions_per_thread = total_dense_prefix_regions /
2612 tasks_for_dense_prefix;
2613 // Give each thread at least 1 region.
2614 if (regions_per_thread == 0) {
2615 regions_per_thread = 1;
2616 }
2617
2618 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2619 if (region_index_start >= region_index_end_dense_prefix) {
2620 break;
2621 }
2622 // region_index_end is not processed
2623 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2624 region_index_end_dense_prefix);
2625 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2626 region_index_start,
2627 region_index_end));
2628 region_index_start = region_index_end;
2629 }
2630 }
2631 // This gets any part of the dense prefix that did not
2632 // fit evenly.
2633 if (region_index_start < region_index_end_dense_prefix) {
2634 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2635 region_index_start,
2636 region_index_end_dense_prefix));
2637 }
2638 }
2639 }
2640
2641 void PSParallelCompact::enqueue_region_stealing_tasks(
2642 GCTaskQueue* q,
2643 ParallelTaskTerminator* terminator_ptr,
2644 uint parallel_gc_threads) {
2645 GCTraceTime tm("steal task setup", print_phases(), true, &_gc_timer);
2646
2647 // Once a thread has drained it's stack, it should try to steal regions from
2648 // other threads.
2649 if (parallel_gc_threads > 1) {
2650 for (uint j = 0; j < parallel_gc_threads; j++) {
2651 q->enqueue(new StealRegionCompactionTask(terminator_ptr));
2652 }
2653 }
2654 }
2655
2656 void PSParallelCompact::compact() {
2657 // trace("5");
2658 GCTraceTime tm("compaction phase", print_phases(), true, &_gc_timer);
2659
2660 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
2661 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
2662 PSOldGen* old_gen = heap->old_gen();
2663 old_gen->start_array()->reset();
2664 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2665 uint active_gc_threads = heap->gc_task_manager()->active_workers();
2666 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2667 ParallelTaskTerminator terminator(active_gc_threads, qset);
2668
2669 GCTaskQueue* q = GCTaskQueue::create();
2670 enqueue_region_draining_tasks(q, active_gc_threads);
2671 enqueue_dense_prefix_tasks(q, active_gc_threads);
2672 enqueue_region_stealing_tasks(q, &terminator, active_gc_threads);
2673
2674 {
2675 GCTraceTime tm_pc("par compact", print_phases(), true, &_gc_timer);
2676
2677 gc_task_manager()->execute_and_wait(q);
2678
2679 #ifdef ASSERT
2680 // Verify that all regions have been processed before the deferred updates.
2681 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2682 verify_complete(SpaceId(id));
2683 }
2684 #endif
2685 }
2686
2687 {
2688 // Update the deferred objects, if any. Any compaction manager can be used.
2689 GCTraceTime tm_du("deferred updates", print_phases(), true, &_gc_timer);
2690 ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2691 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2692 update_deferred_objects(cm, SpaceId(id));
2693 }
2694 }
2695 }
2696
2697 #ifdef ASSERT
2698 void PSParallelCompact::verify_complete(SpaceId space_id) {
2699 // All Regions between space bottom() to new_top() should be marked as filled
2700 // and all Regions between new_top() and top() should be available (i.e.,
2701 // should have been emptied).
2702 ParallelCompactData& sd = summary_data();
2703 SpaceInfo si = _space_info[space_id];
2704 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2705 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2706 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2707 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2708 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2709
2710 bool issued_a_warning = false;
2711
2712 size_t cur_region;
2713 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2714 const RegionData* const c = sd.region(cur_region);
2715 if (!c->completed()) {
2716 warning("region " SIZE_FORMAT " not filled: "
2717 "destination_count=" SIZE_FORMAT,
2718 cur_region, c->destination_count());
2719 issued_a_warning = true;
2720 }
2721 }
2722
2723 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2724 const RegionData* const c = sd.region(cur_region);
2725 if (!c->available()) {
2726 warning("region " SIZE_FORMAT " not empty: "
2727 "destination_count=" SIZE_FORMAT,
2728 cur_region, c->destination_count());
2729 issued_a_warning = true;
2730 }
2731 }
2732
2733 if (issued_a_warning) {
2734 print_region_ranges();
2735 }
2736 }
2737 #endif // #ifdef ASSERT
2738
2739 // Update interior oops in the ranges of regions [beg_region, end_region).
2740 void
2741 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2742 SpaceId space_id,
2743 size_t beg_region,
2744 size_t end_region) {
2745 ParallelCompactData& sd = summary_data();
2746 ParMarkBitMap* const mbm = mark_bitmap();
2747
2748 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2749 HeapWord* const end_addr = sd.region_to_addr(end_region);
2750 assert(beg_region <= end_region, "bad region range");
2751 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2752
2753 #ifdef ASSERT
2754 // Claim the regions to avoid triggering an assert when they are marked as
2755 // filled.
2756 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2757 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2758 }
2759 #endif // #ifdef ASSERT
2760
2761 if (beg_addr != space(space_id)->bottom()) {
2762 // Find the first live object or block of dead space that *starts* in this
2763 // range of regions. If a partial object crosses onto the region, skip it;
2764 // it will be marked for 'deferred update' when the object head is
2765 // processed. If dead space crosses onto the region, it is also skipped; it
2766 // will be filled when the prior region is processed. If neither of those
2767 // apply, the first word in the region is the start of a live object or dead
2768 // space.
2769 assert(beg_addr > space(space_id)->bottom(), "sanity");
2770 const RegionData* const cp = sd.region(beg_region);
2771 if (cp->partial_obj_size() != 0) {
2772 beg_addr = sd.partial_obj_end(beg_region);
2773 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2774 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2775 }
2776 }
2777
2778 if (beg_addr < end_addr) {
2779 // A live object or block of dead space starts in this range of Regions.
2780 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2781
2782 // Create closures and iterate.
2783 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2784 FillClosure fill_closure(cm, space_id);
2785 ParMarkBitMap::IterationStatus status;
2786 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2787 dense_prefix_end);
2788 if (status == ParMarkBitMap::incomplete) {
2789 update_closure.do_addr(update_closure.source());
2790 }
2791 }
2792
2793 // Mark the regions as filled.
2794 RegionData* const beg_cp = sd.region(beg_region);
2795 RegionData* const end_cp = sd.region(end_region);
2796 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2797 cp->set_completed();
2798 }
2799 }
2800
2801 // Return the SpaceId for the space containing addr. If addr is not in the
2802 // heap, last_space_id is returned. In debug mode it expects the address to be
2803 // in the heap and asserts such.
2804 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2805 assert(Universe::heap()->is_in_reserved(addr), "addr not in the heap");
2806
2807 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2808 if (_space_info[id].space()->contains(addr)) {
2809 return SpaceId(id);
2810 }
2811 }
2812
2813 assert(false, "no space contains the addr");
2814 return last_space_id;
2815 }
2816
2817 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2818 SpaceId id) {
2819 assert(id < last_space_id, "bad space id");
2820
2821 ParallelCompactData& sd = summary_data();
2822 const SpaceInfo* const space_info = _space_info + id;
2823 ObjectStartArray* const start_array = space_info->start_array();
2824
2825 const MutableSpace* const space = space_info->space();
2826 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2827 HeapWord* const beg_addr = space_info->dense_prefix();
2828 HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2829
2830 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2831 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2832 const RegionData* cur_region;
2833 for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2834 HeapWord* const addr = cur_region->deferred_obj_addr();
2835 if (addr != NULL) {
2836 if (start_array != NULL) {
2837 start_array->allocate_block(addr);
2838 }
2839 oop(addr)->update_contents(cm);
2840 assert(oop(addr)->is_oop_or_null(), "should be an oop now");
2841 }
2842 }
2843 }
2844
2845 // Skip over count live words starting from beg, and return the address of the
2846 // next live word. Unless marked, the word corresponding to beg is assumed to
2847 // be dead. Callers must either ensure beg does not correspond to the middle of
2848 // an object, or account for those live words in some other way. Callers must
2849 // also ensure that there are enough live words in the range [beg, end) to skip.
2850 HeapWord*
2851 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2852 {
2853 assert(count > 0, "sanity");
2854
2855 ParMarkBitMap* m = mark_bitmap();
2856 idx_t bits_to_skip = m->words_to_bits(count);
2857 idx_t cur_beg = m->addr_to_bit(beg);
2858 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
2859
2860 do {
2861 cur_beg = m->find_obj_beg(cur_beg, search_end);
2862 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2863 const size_t obj_bits = cur_end - cur_beg + 1;
2864 if (obj_bits > bits_to_skip) {
2865 return m->bit_to_addr(cur_beg + bits_to_skip);
2866 }
2867 bits_to_skip -= obj_bits;
2868 cur_beg = cur_end + 1;
2869 } while (bits_to_skip > 0);
2870
2871 // Skipping the desired number of words landed just past the end of an object.
2872 // Find the start of the next object.
2873 cur_beg = m->find_obj_beg(cur_beg, search_end);
2874 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2875 return m->bit_to_addr(cur_beg);
2876 }
2877
2878 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2879 SpaceId src_space_id,
2880 size_t src_region_idx)
2881 {
2882 assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2883
2884 const SplitInfo& split_info = _space_info[src_space_id].split_info();
2885 if (split_info.dest_region_addr() == dest_addr) {
2886 // The partial object ending at the split point contains the first word to
2887 // be copied to dest_addr.
2888 return split_info.first_src_addr();
2889 }
2890
2891 const ParallelCompactData& sd = summary_data();
2892 ParMarkBitMap* const bitmap = mark_bitmap();
2893 const size_t RegionSize = ParallelCompactData::RegionSize;
2894
2895 assert(sd.is_region_aligned(dest_addr), "not aligned");
2896 const RegionData* const src_region_ptr = sd.region(src_region_idx);
2897 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2898 HeapWord* const src_region_destination = src_region_ptr->destination();
2899
2900 assert(dest_addr >= src_region_destination, "wrong src region");
2901 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2902
2903 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2904 HeapWord* const src_region_end = src_region_beg + RegionSize;
2905
2906 HeapWord* addr = src_region_beg;
2907 if (dest_addr == src_region_destination) {
2908 // Return the first live word in the source region.
2909 if (partial_obj_size == 0) {
2910 addr = bitmap->find_obj_beg(addr, src_region_end);
2911 assert(addr < src_region_end, "no objects start in src region");
2912 }
2913 return addr;
2914 }
2915
2916 // Must skip some live data.
2917 size_t words_to_skip = dest_addr - src_region_destination;
2918 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2919
2920 if (partial_obj_size >= words_to_skip) {
2921 // All the live words to skip are part of the partial object.
2922 addr += words_to_skip;
2923 if (partial_obj_size == words_to_skip) {
2924 // Find the first live word past the partial object.
2925 addr = bitmap->find_obj_beg(addr, src_region_end);
2926 assert(addr < src_region_end, "wrong src region");
2927 }
2928 return addr;
2929 }
2930
2931 // Skip over the partial object (if any).
2932 if (partial_obj_size != 0) {
2933 words_to_skip -= partial_obj_size;
2934 addr += partial_obj_size;
2935 }
2936
2937 // Skip over live words due to objects that start in the region.
2938 addr = skip_live_words(addr, src_region_end, words_to_skip);
2939 assert(addr < src_region_end, "wrong src region");
2940 return addr;
2941 }
2942
2943 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2944 SpaceId src_space_id,
2945 size_t beg_region,
2946 HeapWord* end_addr)
2947 {
2948 ParallelCompactData& sd = summary_data();
2949
2950 #ifdef ASSERT
2951 MutableSpace* const src_space = _space_info[src_space_id].space();
2952 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2953 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2954 "src_space_id does not match beg_addr");
2955 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2956 "src_space_id does not match end_addr");
2957 #endif // #ifdef ASSERT
2958
2959 RegionData* const beg = sd.region(beg_region);
2960 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2961
2962 // Regions up to new_top() are enqueued if they become available.
2963 HeapWord* const new_top = _space_info[src_space_id].new_top();
2964 RegionData* const enqueue_end =
2965 sd.addr_to_region_ptr(sd.region_align_up(new_top));
2966
2967 for (RegionData* cur = beg; cur < end; ++cur) {
2968 assert(cur->data_size() > 0, "region must have live data");
2969 cur->decrement_destination_count();
2970 if (cur < enqueue_end && cur->available() && cur->claim()) {
2971 cm->push_region(sd.region(cur));
2972 }
2973 }
2974 }
2975
2976 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2977 SpaceId& src_space_id,
2978 HeapWord*& src_space_top,
2979 HeapWord* end_addr)
2980 {
2981 typedef ParallelCompactData::RegionData RegionData;
2982
2983 ParallelCompactData& sd = PSParallelCompact::summary_data();
2984 const size_t region_size = ParallelCompactData::RegionSize;
2985
2986 size_t src_region_idx = 0;
2987
2988 // Skip empty regions (if any) up to the top of the space.
2989 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2990 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2991 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2992 const RegionData* const top_region_ptr =
2993 sd.addr_to_region_ptr(top_aligned_up);
2994 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2995 ++src_region_ptr;
2996 }
2997
2998 if (src_region_ptr < top_region_ptr) {
2999 // The next source region is in the current space. Update src_region_idx
3000 // and the source address to match src_region_ptr.
3001 src_region_idx = sd.region(src_region_ptr);
3002 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
3003 if (src_region_addr > closure.source()) {
3004 closure.set_source(src_region_addr);
3005 }
3006 return src_region_idx;
3007 }
3008
3009 // Switch to a new source space and find the first non-empty region.
3010 unsigned int space_id = src_space_id + 1;
3011 assert(space_id < last_space_id, "not enough spaces");
3012
3013 HeapWord* const destination = closure.destination();
3014
3015 do {
3016 MutableSpace* space = _space_info[space_id].space();
3017 HeapWord* const bottom = space->bottom();
3018 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
3019
3020 // Iterate over the spaces that do not compact into themselves.
3021 if (bottom_cp->destination() != bottom) {
3022 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
3023 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
3024
3025 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
3026 if (src_cp->live_obj_size() > 0) {
3027 // Found it.
3028 assert(src_cp->destination() == destination,
3029 "first live obj in the space must match the destination");
3030 assert(src_cp->partial_obj_size() == 0,
3031 "a space cannot begin with a partial obj");
3032
3033 src_space_id = SpaceId(space_id);
3034 src_space_top = space->top();
3035 const size_t src_region_idx = sd.region(src_cp);
3036 closure.set_source(sd.region_to_addr(src_region_idx));
3037 return src_region_idx;
3038 } else {
3039 assert(src_cp->data_size() == 0, "sanity");
3040 }
3041 }
3042 }
3043 } while (++space_id < last_space_id);
3044
3045 assert(false, "no source region was found");
3046 return 0;
3047 }
3048
3049 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
3050 {
3051 typedef ParMarkBitMap::IterationStatus IterationStatus;
3052 const size_t RegionSize = ParallelCompactData::RegionSize;
3053 ParMarkBitMap* const bitmap = mark_bitmap();
3054 ParallelCompactData& sd = summary_data();
3055 RegionData* const region_ptr = sd.region(region_idx);
3056
3057 // Get the items needed to construct the closure.
3058 HeapWord* dest_addr = sd.region_to_addr(region_idx);
3059 SpaceId dest_space_id = space_id(dest_addr);
3060 ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
3061 HeapWord* new_top = _space_info[dest_space_id].new_top();
3062 assert(dest_addr < new_top, "sanity");
3063 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
3064
3065 // Get the source region and related info.
3066 size_t src_region_idx = region_ptr->source_region();
3067 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
3068 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
3069
3070 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3071 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
3072
3073 // Adjust src_region_idx to prepare for decrementing destination counts (the
3074 // destination count is not decremented when a region is copied to itself).
3075 if (src_region_idx == region_idx) {
3076 src_region_idx += 1;
3077 }
3078
3079 if (bitmap->is_unmarked(closure.source())) {
3080 // The first source word is in the middle of an object; copy the remainder
3081 // of the object or as much as will fit. The fact that pointer updates were
3082 // deferred will be noted when the object header is processed.
3083 HeapWord* const old_src_addr = closure.source();
3084 closure.copy_partial_obj();
3085 if (closure.is_full()) {
3086 decrement_destination_counts(cm, src_space_id, src_region_idx,
3087 closure.source());
3088 region_ptr->set_deferred_obj_addr(NULL);
3089 region_ptr->set_completed();
3090 return;
3091 }
3092
3093 HeapWord* const end_addr = sd.region_align_down(closure.source());
3094 if (sd.region_align_down(old_src_addr) != end_addr) {
3095 // The partial object was copied from more than one source region.
3096 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3097
3098 // Move to the next source region, possibly switching spaces as well. All
3099 // args except end_addr may be modified.
3100 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3101 end_addr);
3102 }
3103 }
3104
3105 do {
3106 HeapWord* const cur_addr = closure.source();
3107 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
3108 src_space_top);
3109 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
3110
3111 if (status == ParMarkBitMap::incomplete) {
3112 // The last obj that starts in the source region does not end in the
3113 // region.
3114 assert(closure.source() < end_addr, "sanity");
3115 HeapWord* const obj_beg = closure.source();
3116 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
3117 src_space_top);
3118 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
3119 if (obj_end < range_end) {
3120 // The end was found; the entire object will fit.
3121 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
3122 assert(status != ParMarkBitMap::would_overflow, "sanity");
3123 } else {
3124 // The end was not found; the object will not fit.
3125 assert(range_end < src_space_top, "obj cannot cross space boundary");
3126 status = ParMarkBitMap::would_overflow;
3127 }
3128 }
3129
3130 if (status == ParMarkBitMap::would_overflow) {
3131 // The last object did not fit. Note that interior oop updates were
3132 // deferred, then copy enough of the object to fill the region.
3133 region_ptr->set_deferred_obj_addr(closure.destination());
3134 status = closure.copy_until_full(); // copies from closure.source()
3135
3136 decrement_destination_counts(cm, src_space_id, src_region_idx,
3137 closure.source());
3138 region_ptr->set_completed();
3139 return;
3140 }
3141
3142 if (status == ParMarkBitMap::full) {
3143 decrement_destination_counts(cm, src_space_id, src_region_idx,
3144 closure.source());
3145 region_ptr->set_deferred_obj_addr(NULL);
3146 region_ptr->set_completed();
3147 return;
3148 }
3149
3150 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3151
3152 // Move to the next source region, possibly switching spaces as well. All
3153 // args except end_addr may be modified.
3154 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3155 end_addr);
3156 } while (true);
3157 }
3158
3159 void
3160 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
3161 const MutableSpace* sp = space(space_id);
3162 if (sp->is_empty()) {
3163 return;
3164 }
3165
3166 ParallelCompactData& sd = PSParallelCompact::summary_data();
3167 ParMarkBitMap* const bitmap = mark_bitmap();
3168 HeapWord* const dp_addr = dense_prefix(space_id);
3169 HeapWord* beg_addr = sp->bottom();
3170 HeapWord* end_addr = sp->top();
3171
3172 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
3173
3174 const size_t beg_region = sd.addr_to_region_idx(beg_addr);
3175 const size_t dp_region = sd.addr_to_region_idx(dp_addr);
3176 if (beg_region < dp_region) {
3177 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
3178 }
3179
3180 // The destination of the first live object that starts in the region is one
3181 // past the end of the partial object entering the region (if any).
3182 HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3183 HeapWord* const new_top = _space_info[space_id].new_top();
3184 assert(new_top >= dest_addr, "bad new_top value");
3185 const size_t words = pointer_delta(new_top, dest_addr);
3186
3187 if (words > 0) {
3188 ObjectStartArray* start_array = _space_info[space_id].start_array();
3189 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3190
3191 ParMarkBitMap::IterationStatus status;
3192 status = bitmap->iterate(&closure, dest_addr, end_addr);
3193 assert(status == ParMarkBitMap::full, "iteration not complete");
3194 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3195 "live objects skipped because closure is full");
3196 }
3197 }
3198
3199 jlong PSParallelCompact::millis_since_last_gc() {
3200 // We need a monotonically non-deccreasing time in ms but
3201 // os::javaTimeMillis() does not guarantee monotonicity.
3202 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3203 jlong ret_val = now - _time_of_last_gc;
3204 // XXX See note in genCollectedHeap::millis_since_last_gc().
3205 if (ret_val < 0) {
3206 NOT_PRODUCT(warning("time warp: "INT64_FORMAT, ret_val);)
3207 return 0;
3208 }
3209 return ret_val;
3210 }
3211
3212 void PSParallelCompact::reset_millis_since_last_gc() {
3213 // We need a monotonically non-deccreasing time in ms but
3214 // os::javaTimeMillis() does not guarantee monotonicity.
3215 _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3216 }
3217
3218 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3219 {
3220 if (source() != destination()) {
3221 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3222 Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3223 }
3224 update_state(words_remaining());
3225 assert(is_full(), "sanity");
3226 return ParMarkBitMap::full;
3227 }
3228
3229 void MoveAndUpdateClosure::copy_partial_obj()
3230 {
3231 size_t words = words_remaining();
3232
3233 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3234 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3235 if (end_addr < range_end) {
3236 words = bitmap()->obj_size(source(), end_addr);
3237 }
3238
3239 // This test is necessary; if omitted, the pointer updates to a partial object
3240 // that crosses the dense prefix boundary could be overwritten.
3241 if (source() != destination()) {
3242 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3243 Copy::aligned_conjoint_words(source(), destination(), words);
3244 }
3245 update_state(words);
3246 }
3247
3248 ParMarkBitMapClosure::IterationStatus
3249 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3250 assert(destination() != NULL, "sanity");
3251 assert(bitmap()->obj_size(addr) == words, "bad size");
3252
3253 _source = addr;
3254 assert(PSParallelCompact::summary_data().calc_new_pointer(source()) ==
3255 destination(), "wrong destination");
3256
3257 if (words > words_remaining()) {
3258 return ParMarkBitMap::would_overflow;
3259 }
3260
3261 // The start_array must be updated even if the object is not moving.
3262 if (_start_array != NULL) {
3263 _start_array->allocate_block(destination());
3264 }
3265
3266 if (destination() != source()) {
3267 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3268 Copy::aligned_conjoint_words(source(), destination(), words);
3269 }
3270
3271 oop moved_oop = (oop) destination();
3272 moved_oop->update_contents(compaction_manager());
3273 assert(moved_oop->is_oop_or_null(), "Object should be whole at this point");
3274
3275 update_state(words);
3276 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3277 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3278 }
3279
3280 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3281 ParCompactionManager* cm,
3282 PSParallelCompact::SpaceId space_id) :
3283 ParMarkBitMapClosure(mbm, cm),
3284 _space_id(space_id),
3285 _start_array(PSParallelCompact::start_array(space_id))
3286 {
3287 }
3288
3289 // Updates the references in the object to their new values.
3290 ParMarkBitMapClosure::IterationStatus
3291 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3292 do_addr(addr);
3293 return ParMarkBitMap::incomplete;
3294 }