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