1 #ifdef USE_PRAGMA_IDENT_SRC
2 #pragma ident "@(#)psParallelCompact.cpp 1.64 08/06/19 15:33:02 JVM"
3 #endif
4 /*
5 * Copyright 2005-2008 Sun Microsystems, Inc. All Rights Reserved.
6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
7 *
8 * This code is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 only, as
10 * published by the Free Software Foundation.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
23 * CA 95054 USA or visit www.sun.com if you need additional information or
24 * have any questions.
25 *
26 */
27
28 #include "incls/_precompiled.incl"
29 #include "incls/_psParallelCompact.cpp.incl"
30
31 #include <math.h>
32
33 // All sizes are in HeapWords.
34 const size_t ParallelCompactData::Log2RegionSize = 9; // 512 words
35 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
36 const size_t ParallelCompactData::RegionSizeBytes =
37 RegionSize << LogHeapWordSize;
38 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
39 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
40 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
41
42 const ParallelCompactData::RegionData::region_sz_t
43 ParallelCompactData::RegionData::dc_shift = 27;
44
45 const ParallelCompactData::RegionData::region_sz_t
46 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
47
48 const ParallelCompactData::RegionData::region_sz_t
49 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
50
51 const ParallelCompactData::RegionData::region_sz_t
52 ParallelCompactData::RegionData::los_mask = ~dc_mask;
53
54 const ParallelCompactData::RegionData::region_sz_t
55 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
56
57 const ParallelCompactData::RegionData::region_sz_t
58 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
59
60 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
61 bool PSParallelCompact::_print_phases = false;
62
63 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
64 klassOop PSParallelCompact::_updated_int_array_klass_obj = NULL;
65
66 double PSParallelCompact::_dwl_mean;
67 double PSParallelCompact::_dwl_std_dev;
68 double PSParallelCompact::_dwl_first_term;
69 double PSParallelCompact::_dwl_adjustment;
70 #ifdef ASSERT
71 bool PSParallelCompact::_dwl_initialized = false;
72 #endif // #ifdef ASSERT
73
74 #ifdef VALIDATE_MARK_SWEEP
75 GrowableArray<void*>* PSParallelCompact::_root_refs_stack = NULL;
76 GrowableArray<oop> * PSParallelCompact::_live_oops = NULL;
77 GrowableArray<oop> * PSParallelCompact::_live_oops_moved_to = NULL;
78 GrowableArray<size_t>* PSParallelCompact::_live_oops_size = NULL;
79 size_t PSParallelCompact::_live_oops_index = 0;
80 size_t PSParallelCompact::_live_oops_index_at_perm = 0;
81 GrowableArray<void*>* PSParallelCompact::_other_refs_stack = NULL;
82 GrowableArray<void*>* PSParallelCompact::_adjusted_pointers = NULL;
83 bool PSParallelCompact::_pointer_tracking = false;
84 bool PSParallelCompact::_root_tracking = true;
85
86 GrowableArray<HeapWord*>* PSParallelCompact::_cur_gc_live_oops = NULL;
87 GrowableArray<HeapWord*>* PSParallelCompact::_cur_gc_live_oops_moved_to = NULL;
88 GrowableArray<size_t> * PSParallelCompact::_cur_gc_live_oops_size = NULL;
89 GrowableArray<HeapWord*>* PSParallelCompact::_last_gc_live_oops = NULL;
90 GrowableArray<HeapWord*>* PSParallelCompact::_last_gc_live_oops_moved_to = NULL;
91 GrowableArray<size_t> * PSParallelCompact::_last_gc_live_oops_size = NULL;
92 #endif
93
94 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
95 HeapWord* destination)
96 {
97 assert(src_region_idx != 0, "invalid src_region_idx");
98 assert(partial_obj_size != 0, "invalid partial_obj_size argument");
99 assert(destination != NULL, "invalid destination argument");
100
101 _src_region_idx = src_region_idx;
102 _partial_obj_size = partial_obj_size;
103 _destination = destination;
104
105 // These fields may not be updated below, so make sure they're clear.
106 assert(_dest_region_addr == NULL, "should have been cleared");
107 assert(_first_src_addr == NULL, "should have been cleared");
108
109 // Determine the number of destination regions for the partial object.
110 HeapWord* const last_word = destination + partial_obj_size - 1;
111 const ParallelCompactData& sd = PSParallelCompact::summary_data();
112 HeapWord* const beg_region_addr = sd.region_align_down(destination);
113 HeapWord* const end_region_addr = sd.region_align_down(last_word);
114
115 if (beg_region_addr == end_region_addr) {
116 // One destination region.
117 _destination_count = 1;
118 if (end_region_addr == destination) {
119 // The destination falls on a region boundary, thus the first word of the
120 // partial object will be the first word copied to the destination region.
121 _dest_region_addr = end_region_addr;
122 _first_src_addr = sd.region_to_addr(src_region_idx);
123 }
124 } else {
125 // Two destination regions. When copied, the partial object will cross a
126 // destination region boundary, so a word somewhere within the partial
127 // object will be the first word copied to the second destination region.
128 _destination_count = 2;
129 _dest_region_addr = end_region_addr;
130 const size_t ofs = pointer_delta(end_region_addr, destination);
131 assert(ofs < _partial_obj_size, "sanity");
132 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
133 }
134 }
135
136 void SplitInfo::clear()
137 {
138 _src_region_idx = 0;
139 _partial_obj_size = 0;
140 _destination = NULL;
141 _destination_count = 0;
142 _dest_region_addr = NULL;
143 _first_src_addr = NULL;
144 assert(!is_valid(), "sanity");
145 }
146
147 #ifdef ASSERT
148 void SplitInfo::verify_clear()
149 {
150 assert(_src_region_idx == 0, "not clear");
151 assert(_partial_obj_size == 0, "not clear");
152 assert(_destination == NULL, "not clear");
153 assert(_destination_count == 0, "not clear");
154 assert(_dest_region_addr == NULL, "not clear");
155 assert(_first_src_addr == NULL, "not clear");
156 }
157 #endif // #ifdef ASSERT
158
159
160 #ifndef PRODUCT
161 const char* PSParallelCompact::space_names[] = {
162 "perm", "old ", "eden", "from", "to "
163 };
164
165 void PSParallelCompact::print_region_ranges()
166 {
167 tty->print_cr("space bottom top end new_top");
168 tty->print_cr("------ ---------- ---------- ---------- ----------");
169
170 for (unsigned int id = 0; id < last_space_id; ++id) {
171 const MutableSpace* space = _space_info[id].space();
172 tty->print_cr("%u %s "
173 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
174 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
175 id, space_names[id],
176 summary_data().addr_to_region_idx(space->bottom()),
177 summary_data().addr_to_region_idx(space->top()),
178 summary_data().addr_to_region_idx(space->end()),
179 summary_data().addr_to_region_idx(_space_info[id].new_top()));
180 }
181 }
182
183 void
184 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
185 {
186 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7)
187 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5)
188
189 ParallelCompactData& sd = PSParallelCompact::summary_data();
190 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
191 tty->print_cr(REGION_IDX_FORMAT " " PTR_FORMAT " "
192 REGION_IDX_FORMAT " " PTR_FORMAT " "
193 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
194 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
195 i, c->data_location(), dci, c->destination(),
196 c->partial_obj_size(), c->live_obj_size(),
197 c->data_size(), c->source_region(), c->destination_count());
198
199 #undef REGION_IDX_FORMAT
200 #undef REGION_DATA_FORMAT
201 }
202
203 void
204 print_generic_summary_data(ParallelCompactData& summary_data,
205 HeapWord* const beg_addr,
206 HeapWord* const end_addr)
207 {
208 size_t total_words = 0;
209 size_t i = summary_data.addr_to_region_idx(beg_addr);
210 const size_t last = summary_data.addr_to_region_idx(end_addr);
211 HeapWord* pdest = 0;
212
213 while (i <= last) {
214 ParallelCompactData::RegionData* c = summary_data.region(i);
215 if (c->data_size() != 0 || c->destination() != pdest) {
216 print_generic_summary_region(i, c);
217 total_words += c->data_size();
218 pdest = c->destination();
219 }
220 ++i;
221 }
222
223 tty->print_cr("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
224 }
225
226 void
227 print_generic_summary_data(ParallelCompactData& summary_data,
228 SpaceInfo* space_info)
229 {
230 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
231 const MutableSpace* space = space_info[id].space();
232 print_generic_summary_data(summary_data, space->bottom(),
233 MAX2(space->top(), space_info[id].new_top()));
234 }
235 }
236
237 void
238 print_initial_summary_region(size_t i,
239 const ParallelCompactData::RegionData* c,
240 bool newline = true)
241 {
242 tty->print(SIZE_FORMAT_W(5) " " PTR_FORMAT " "
243 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " "
244 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
245 i, c->destination(),
246 c->partial_obj_size(), c->live_obj_size(),
247 c->data_size(), c->source_region(), c->destination_count());
248 if (newline) tty->cr();
249 }
250
251 void
252 print_initial_summary_data(ParallelCompactData& summary_data,
253 const MutableSpace* space) {
254 if (space->top() == space->bottom()) {
255 return;
256 }
257
258 const size_t region_size = ParallelCompactData::RegionSize;
259 typedef ParallelCompactData::RegionData RegionData;
260 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
261 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
262 const RegionData* c = summary_data.region(end_region - 1);
263 HeapWord* end_addr = c->destination() + c->data_size();
264 const size_t live_in_space = pointer_delta(end_addr, space->bottom());
265
266 // Print (and count) the full regions at the beginning of the space.
267 size_t full_region_count = 0;
268 size_t i = summary_data.addr_to_region_idx(space->bottom());
269 while (i < end_region && summary_data.region(i)->data_size() == region_size) {
270 print_initial_summary_region(i, summary_data.region(i));
271 ++full_region_count;
272 ++i;
273 }
274
275 size_t live_to_right = live_in_space - full_region_count * region_size;
276
277 double max_reclaimed_ratio = 0.0;
278 size_t max_reclaimed_ratio_region = 0;
279 size_t max_dead_to_right = 0;
280 size_t max_live_to_right = 0;
281
282 // Print the 'reclaimed ratio' for regions while there is something live in
283 // the region or to the right of it. The remaining regions are empty (and
284 // uninteresting), and computing the ratio will result in division by 0.
285 while (i < end_region && live_to_right > 0) {
286 c = summary_data.region(i);
287 HeapWord* const region_addr = summary_data.region_to_addr(i);
288 const size_t used_to_right = pointer_delta(space->top(), region_addr);
289 const size_t dead_to_right = used_to_right - live_to_right;
290 const double reclaimed_ratio = double(dead_to_right) / live_to_right;
291
292 if (reclaimed_ratio > max_reclaimed_ratio) {
293 max_reclaimed_ratio = reclaimed_ratio;
294 max_reclaimed_ratio_region = i;
295 max_dead_to_right = dead_to_right;
296 max_live_to_right = live_to_right;
297 }
298
299 print_initial_summary_region(i, c, false);
300 tty->print_cr(" %12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
301 reclaimed_ratio, dead_to_right, live_to_right);
302
303 live_to_right -= c->data_size();
304 ++i;
305 }
306
307 // Any remaining regions are empty. Print one more if there is one.
308 if (i < end_region) {
309 print_initial_summary_region(i, summary_data.region(i));
310 }
311
312 tty->print_cr("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " "
313 "l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
314 max_reclaimed_ratio_region, max_dead_to_right,
315 max_live_to_right, max_reclaimed_ratio);
316 }
317
318 void
319 print_initial_summary_data(ParallelCompactData& summary_data,
320 SpaceInfo* space_info) {
321 unsigned int id = PSParallelCompact::perm_space_id;
322 const MutableSpace* space;
323 do {
324 space = space_info[id].space();
325 print_initial_summary_data(summary_data, space);
326 } while (++id < PSParallelCompact::eden_space_id);
327
328 do {
329 space = space_info[id].space();
330 print_generic_summary_data(summary_data, space->bottom(), space->top());
331 } while (++id < PSParallelCompact::last_space_id);
332 }
333 #endif // #ifndef PRODUCT
334
335 #ifdef ASSERT
336 size_t add_obj_count;
337 size_t add_obj_size;
338 size_t mark_bitmap_count;
339 size_t mark_bitmap_size;
340 #endif // #ifdef ASSERT
341
342 ParallelCompactData::ParallelCompactData()
343 {
344 _region_start = 0;
345
346 _region_vspace = 0;
347 _region_data = 0;
348 _region_count = 0;
349 }
350
351 bool ParallelCompactData::initialize(MemRegion covered_region)
352 {
353 _region_start = covered_region.start();
354 const size_t region_size = covered_region.word_size();
355 DEBUG_ONLY(_region_end = _region_start + region_size;)
356
357 assert(region_align_down(_region_start) == _region_start,
358 "region start not aligned");
359 assert((region_size & RegionSizeOffsetMask) == 0,
360 "region size not a multiple of RegionSize");
361
362 bool result = initialize_region_data(region_size);
363
364 return result;
365 }
366
367 PSVirtualSpace*
368 ParallelCompactData::create_vspace(size_t count, size_t element_size)
369 {
370 const size_t raw_bytes = count * element_size;
371 const size_t page_sz = os::page_size_for_region(raw_bytes, raw_bytes, 10);
372 const size_t granularity = os::vm_allocation_granularity();
373 const size_t bytes = align_size_up(raw_bytes, MAX2(page_sz, granularity));
374
375 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
376 MAX2(page_sz, granularity);
377 ReservedSpace rs(bytes, rs_align, rs_align > 0);
378 os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(),
379 rs.size());
380 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
381 if (vspace != 0) {
382 if (vspace->expand_by(bytes)) {
383 return vspace;
384 }
385 delete vspace;
386 // Release memory reserved in the space.
387 rs.release();
388 }
389
390 return 0;
391 }
392
393 bool ParallelCompactData::initialize_region_data(size_t region_size)
394 {
395 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
396 _region_vspace = create_vspace(count, sizeof(RegionData));
397 if (_region_vspace != 0) {
398 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
399 _region_count = count;
400 return true;
401 }
402 return false;
403 }
404
405 void ParallelCompactData::clear()
406 {
407 memset(_region_data, 0, _region_vspace->committed_size());
408 }
409
410 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
411 assert(beg_region <= _region_count, "beg_region out of range");
412 assert(end_region <= _region_count, "end_region out of range");
413
414 const size_t region_cnt = end_region - beg_region;
415 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
416 }
417
418 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
419 {
420 const RegionData* cur_cp = region(region_idx);
421 const RegionData* const end_cp = region(region_count() - 1);
422
423 HeapWord* result = region_to_addr(region_idx);
424 if (cur_cp < end_cp) {
425 do {
426 result += cur_cp->partial_obj_size();
427 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
428 }
429 return result;
430 }
431
432 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
433 {
434 const size_t obj_ofs = pointer_delta(addr, _region_start);
435 const size_t beg_region = obj_ofs >> Log2RegionSize;
436 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
437
438 DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
439 DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
440
441 if (beg_region == end_region) {
442 // All in one region.
443 _region_data[beg_region].add_live_obj(len);
444 return;
445 }
446
447 // First region.
448 const size_t beg_ofs = region_offset(addr);
449 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
450
451 klassOop klass = ((oop)addr)->klass();
452 // Middle regions--completely spanned by this object.
453 for (size_t region = beg_region + 1; region < end_region; ++region) {
454 _region_data[region].set_partial_obj_size(RegionSize);
455 _region_data[region].set_partial_obj_addr(addr);
456 }
457
458 // Last region.
459 const size_t end_ofs = region_offset(addr + len - 1);
460 _region_data[end_region].set_partial_obj_size(end_ofs + 1);
461 _region_data[end_region].set_partial_obj_addr(addr);
462 }
463
464 void
465 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
466 {
467 assert(region_offset(beg) == 0, "not RegionSize aligned");
468 assert(region_offset(end) == 0, "not RegionSize aligned");
469
470 size_t cur_region = addr_to_region_idx(beg);
471 const size_t end_region = addr_to_region_idx(end);
472 HeapWord* addr = beg;
473 while (cur_region < end_region) {
474 _region_data[cur_region].set_destination(addr);
475 _region_data[cur_region].set_destination_count(0);
476 _region_data[cur_region].set_source_region(cur_region);
477 _region_data[cur_region].set_data_location(addr);
478
479 // Update live_obj_size so the region appears completely full.
480 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
481 _region_data[cur_region].set_live_obj_size(live_size);
482
483 ++cur_region;
484 addr += RegionSize;
485 }
486 }
487
488 // Find the point at which a space can be split and, if necessary, record the
489 // split point.
490 //
491 // If the current src region (which overflowed the destination space) doesn't
492 // have a partial object, the split point is at the beginning of the current src
493 // region (an "easy" split, no extra bookkeeping required).
494 //
495 // If the current src region has a partial object, the split point is in the
496 // region where that partial object starts (call it the split_region). If
497 // split_region has a partial object, then the split point is just after that
498 // partial object (a "hard" split where we have to record the split data and
499 // zero the partial_obj_size field). With a "hard" split, we know that the
500 // partial_obj ends within split_region because the partial object that caused
501 // the overflow starts in split_region. If split_region doesn't have a partial
502 // obj, then the split is at the beginning of split_region (another "easy"
503 // split).
504 HeapWord*
505 ParallelCompactData::summarize_split_space(size_t src_region,
506 SplitInfo& split_info,
507 HeapWord* destination,
508 HeapWord* target_end,
509 HeapWord** target_next)
510 {
511 assert(destination <= target_end, "sanity");
512 assert(destination + _region_data[src_region].data_size() > target_end,
513 "region should not fit into target space");
514
515 size_t split_region = src_region;
516 HeapWord* split_destination = destination;
517 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
518
519 if (destination + partial_obj_size > target_end) {
520 // The split point is just after the partial object (if any) in the
521 // src_region that contains the start of the object that overflowed the
522 // destination space.
523 //
524 // Find the start of the "overflow" object and set split_region to the
525 // region containing it.
526 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
527 split_region = addr_to_region_idx(overflow_obj);
528
529 // Clear the source_region field of all destination regions whose first word
530 // came from data after the split point (a non-null source_region field
531 // implies a region must be filled).
532 //
533 // An alternative to the simple loop below: clear during post_compact(),
534 // which uses memcpy instead of individual stores, and is easy to
535 // parallelize. (The downside is that it clears the entire RegionData
536 // object as opposed to just one field.)
537 //
538 // post_compact() would have to clear the summary data up to the highest
539 // address that was written during the summary phase, which would be
540 //
541 // max(top, max(new_top, clear_top))
542 //
543 // where clear_top is a new field in SpaceInfo. Would have to set clear_top
544 // to destination + partial_obj_size, where both have the values passed to
545 // this routine.
546 const RegionData* const sr = region(split_region);
547 const size_t beg_idx =
548 addr_to_region_idx(region_align_up(sr->destination() +
549 sr->partial_obj_size()));
550 const size_t end_idx =
551 addr_to_region_idx(region_align_up(destination + partial_obj_size));
552
553 if (TraceParallelOldGCSummaryPhase) {
554 gclog_or_tty->print_cr("split: clearing source_region field in ["
555 SIZE_FORMAT ", " SIZE_FORMAT ")",
556 beg_idx, end_idx);
557 }
558 for (size_t idx = beg_idx; idx < end_idx; ++idx) {
559 _region_data[idx].set_source_region(0);
560 }
561
562 // Set split_destination and partial_obj_size to reflect the split region.
563 split_destination = sr->destination();
564 partial_obj_size = sr->partial_obj_size();
565 }
566
567 // The split is recorded only if a partial object extends onto the region.
568 if (partial_obj_size != 0) {
569 _region_data[split_region].set_partial_obj_size(0);
570 split_info.record(split_region, partial_obj_size, split_destination);
571 }
572
573 // Setup the continuation addresses.
574 *target_next = split_destination + partial_obj_size;
575 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
576
577 if (TraceParallelOldGCSummaryPhase) {
578 const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
579 gclog_or_tty->print_cr("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT
580 " pos=" SIZE_FORMAT,
581 split_type, source_next, split_region,
582 partial_obj_size);
583 gclog_or_tty->print_cr("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT
584 " tn=" PTR_FORMAT,
585 split_type, split_destination,
586 addr_to_region_idx(split_destination),
587 *target_next);
588
589 if (partial_obj_size != 0) {
590 HeapWord* const po_beg = split_info.destination();
591 HeapWord* const po_end = po_beg + split_info.partial_obj_size();
592 gclog_or_tty->print_cr("%s split: "
593 "po_beg=" PTR_FORMAT " " SIZE_FORMAT " "
594 "po_end=" PTR_FORMAT " " SIZE_FORMAT,
595 split_type,
596 po_beg, addr_to_region_idx(po_beg),
597 po_end, addr_to_region_idx(po_end));
598 }
599 }
600
601 return source_next;
602 }
603
604 bool ParallelCompactData::summarize(SplitInfo& split_info,
605 HeapWord* source_beg, HeapWord* source_end,
606 HeapWord** source_next,
607 HeapWord* target_beg, HeapWord* target_end,
608 HeapWord** target_next)
609 {
610 if (TraceParallelOldGCSummaryPhase) {
611 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
612 tty->print_cr("sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
613 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
614 source_beg, source_end, source_next_val,
615 target_beg, target_end, *target_next);
616 }
617
618 size_t cur_region = addr_to_region_idx(source_beg);
619 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
620
621 HeapWord *dest_addr = target_beg;
622 while (cur_region < end_region) {
623 // The destination must be set even if the region has no data.
624 _region_data[cur_region].set_destination(dest_addr);
625
626 size_t words = _region_data[cur_region].data_size();
627 if (words > 0) {
628 // If cur_region does not fit entirely into the target space, find a point
629 // at which the source space can be 'split' so that part is copied to the
630 // target space and the rest is copied elsewhere.
631 if (dest_addr + words > target_end) {
632 assert(source_next != NULL, "source_next is NULL when splitting");
633 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
634 target_end, target_next);
635 return false;
636 }
637
638 // Compute the destination_count for cur_region, and if necessary, update
639 // source_region for a destination region. The source_region field is
640 // updated if cur_region is the first (left-most) region to be copied to a
641 // destination region.
642 //
643 // The destination_count calculation is a bit subtle. A region that has
644 // data that compacts into itself does not count itself as a destination.
645 // This maintains the invariant that a zero count means the region is
646 // available and can be claimed and then filled.
647 uint destination_count = 0;
648 if (split_info.is_split(cur_region)) {
649 // The current region has been split: the partial object will be copied
650 // to one destination space and the remaining data will be copied to
651 // another destination space. Adjust the initial destination_count and,
652 // if necessary, set the source_region field if the partial object will
653 // cross a destination region boundary.
654 destination_count = split_info.destination_count();
655 if (destination_count == 2) {
656 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
657 _region_data[dest_idx].set_source_region(cur_region);
658 }
659 }
660
661 HeapWord* const last_addr = dest_addr + words - 1;
662 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
663 const size_t dest_region_2 = addr_to_region_idx(last_addr);
664
665 // Initially assume that the destination regions will be the same and
666 // adjust the value below if necessary. Under this assumption, if
667 // cur_region == dest_region_2, then cur_region will be compacted
668 // completely into itself.
669 destination_count += cur_region == dest_region_2 ? 0 : 1;
670 if (dest_region_1 != dest_region_2) {
671 // Destination regions differ; adjust destination_count.
672 destination_count += 1;
673 // Data from cur_region will be copied to the start of dest_region_2.
674 _region_data[dest_region_2].set_source_region(cur_region);
675 } else if (region_offset(dest_addr) == 0) {
676 // Data from cur_region will be copied to the start of the destination
677 // region.
678 _region_data[dest_region_1].set_source_region(cur_region);
679 }
680
681 _region_data[cur_region].set_destination_count(destination_count);
682 _region_data[cur_region].set_data_location(region_to_addr(cur_region));
683 dest_addr += words;
684 }
685
686 ++cur_region;
687 }
688
689 *target_next = dest_addr;
690 return true;
691 }
692
693 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) {
694 assert(addr != NULL, "Should detect NULL oop earlier");
695 assert(PSParallelCompact::gc_heap()->is_in(addr), "addr not in heap");
696 #ifdef ASSERT
697 if (PSParallelCompact::mark_bitmap()->is_unmarked(addr)) {
698 gclog_or_tty->print_cr("calc_new_pointer:: addr " PTR_FORMAT, addr);
699 }
700 #endif
701 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "obj not marked");
702
703 // Region covering the object.
704 size_t region_index = addr_to_region_idx(addr);
705 const RegionData* const region_ptr = region(region_index);
706 HeapWord* const region_addr = region_align_down(addr);
707
708 assert(addr < region_addr + RegionSize, "Region does not cover object");
709 assert(addr_to_region_ptr(region_addr) == region_ptr, "sanity check");
710
711 HeapWord* result = region_ptr->destination();
712
713 // If all the data in the region is live, then the new location of the object
714 // can be calculated from the destination of the region plus the offset of the
715 // object in the region.
716 if (region_ptr->data_size() == RegionSize) {
717 result += pointer_delta(addr, region_addr);
718 return result;
719 }
720
721 // The new location of the object is
722 // region destination +
723 // size of the partial object extending onto the region +
724 // sizes of the live objects in the Region that are to the left of addr
725 const size_t partial_obj_size = region_ptr->partial_obj_size();
726 HeapWord* const search_start = region_addr + partial_obj_size;
727
728 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
729 size_t live_to_left = bitmap->live_words_in_range(search_start, oop(addr));
730
731 result += partial_obj_size + live_to_left;
732 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result);)
733 return result;
734 }
735
736 klassOop ParallelCompactData::calc_new_klass(klassOop old_klass) {
737 klassOop updated_klass;
738 if (PSParallelCompact::should_update_klass(old_klass)) {
739 updated_klass = (klassOop) calc_new_pointer(old_klass);
740 } else {
741 updated_klass = old_klass;
742 }
743
744 return updated_klass;
745 }
746
747 #ifdef ASSERT
748 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
749 {
750 const size_t* const beg = (const size_t*)vspace->committed_low_addr();
751 const size_t* const end = (const size_t*)vspace->committed_high_addr();
752 for (const size_t* p = beg; p < end; ++p) {
753 assert(*p == 0, "not zero");
754 }
755 }
756
757 void ParallelCompactData::verify_clear()
758 {
759 verify_clear(_region_vspace);
760 }
761 #endif // #ifdef ASSERT
762
763 #ifdef NOT_PRODUCT
764 ParallelCompactData::RegionData* debug_region(size_t region_index) {
765 ParallelCompactData& sd = PSParallelCompact::summary_data();
766 return sd.region(region_index);
767 }
768 #endif
769
770 elapsedTimer PSParallelCompact::_accumulated_time;
771 unsigned int PSParallelCompact::_total_invocations = 0;
772 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
773 jlong PSParallelCompact::_time_of_last_gc = 0;
774 CollectorCounters* PSParallelCompact::_counters = NULL;
775 ParMarkBitMap PSParallelCompact::_mark_bitmap;
776 ParallelCompactData PSParallelCompact::_summary_data;
777
778 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
779
780 void PSParallelCompact::IsAliveClosure::do_object(oop p) { ShouldNotReachHere(); }
781 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
782
783 void PSParallelCompact::KeepAliveClosure::do_oop(oop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
784 void PSParallelCompact::KeepAliveClosure::do_oop(narrowOop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
785
786 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_root_pointer_closure(true);
787 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_pointer_closure(false);
788
789 void PSParallelCompact::AdjustPointerClosure::do_oop(oop* p) { adjust_pointer(p, _is_root); }
790 void PSParallelCompact::AdjustPointerClosure::do_oop(narrowOop* p) { adjust_pointer(p, _is_root); }
791
792 void PSParallelCompact::FollowStackClosure::do_void() { follow_stack(_compaction_manager); }
793
794 void PSParallelCompact::MarkAndPushClosure::do_oop(oop* p) { mark_and_push(_compaction_manager, p); }
795 void PSParallelCompact::MarkAndPushClosure::do_oop(narrowOop* p) { mark_and_push(_compaction_manager, p); }
796
797 void PSParallelCompact::post_initialize() {
798 ParallelScavengeHeap* heap = gc_heap();
799 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
800
801 MemRegion mr = heap->reserved_region();
802 _ref_processor = ReferenceProcessor::create_ref_processor(
803 mr, // span
804 true, // atomic_discovery
805 true, // mt_discovery
806 &_is_alive_closure,
807 ParallelGCThreads,
808 ParallelRefProcEnabled);
809 _counters = new CollectorCounters("PSParallelCompact", 1);
810
811 // Initialize static fields in ParCompactionManager.
812 ParCompactionManager::initialize(mark_bitmap());
813 }
814
815 bool PSParallelCompact::initialize() {
816 ParallelScavengeHeap* heap = gc_heap();
817 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
818 MemRegion mr = heap->reserved_region();
819
820 // Was the old gen get allocated successfully?
821 if (!heap->old_gen()->is_allocated()) {
822 return false;
823 }
824
825 initialize_space_info();
826 initialize_dead_wood_limiter();
827
828 if (!_mark_bitmap.initialize(mr)) {
829 vm_shutdown_during_initialization("Unable to allocate bit map for "
830 "parallel garbage collection for the requested heap size.");
831 return false;
832 }
833
834 if (!_summary_data.initialize(mr)) {
835 vm_shutdown_during_initialization("Unable to allocate tables for "
836 "parallel garbage collection for the requested heap size.");
837 return false;
838 }
839
840 return true;
841 }
842
843 void PSParallelCompact::initialize_space_info()
844 {
845 memset(&_space_info, 0, sizeof(_space_info));
846
847 ParallelScavengeHeap* heap = gc_heap();
848 PSYoungGen* young_gen = heap->young_gen();
849 MutableSpace* perm_space = heap->perm_gen()->object_space();
850
851 _space_info[perm_space_id].set_space(perm_space);
852 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
853 _space_info[eden_space_id].set_space(young_gen->eden_space());
854 _space_info[from_space_id].set_space(young_gen->from_space());
855 _space_info[to_space_id].set_space(young_gen->to_space());
856
857 _space_info[perm_space_id].set_start_array(heap->perm_gen()->start_array());
858 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
859
860 _space_info[perm_space_id].set_min_dense_prefix(perm_space->top());
861 if (TraceParallelOldGCDensePrefix) {
862 tty->print_cr("perm min_dense_prefix=" PTR_FORMAT,
863 _space_info[perm_space_id].min_dense_prefix());
864 }
865 }
866
867 void PSParallelCompact::initialize_dead_wood_limiter()
868 {
869 const size_t max = 100;
870 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
871 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
872 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
873 DEBUG_ONLY(_dwl_initialized = true;)
874 _dwl_adjustment = normal_distribution(1.0);
875 }
876
877 // Simple class for storing info about the heap at the start of GC, to be used
878 // after GC for comparison/printing.
879 class PreGCValues {
880 public:
881 PreGCValues() { }
882 PreGCValues(ParallelScavengeHeap* heap) { fill(heap); }
883
884 void fill(ParallelScavengeHeap* heap) {
885 _heap_used = heap->used();
886 _young_gen_used = heap->young_gen()->used_in_bytes();
887 _old_gen_used = heap->old_gen()->used_in_bytes();
888 _perm_gen_used = heap->perm_gen()->used_in_bytes();
889 };
890
891 size_t heap_used() const { return _heap_used; }
892 size_t young_gen_used() const { return _young_gen_used; }
893 size_t old_gen_used() const { return _old_gen_used; }
894 size_t perm_gen_used() const { return _perm_gen_used; }
895
896 private:
897 size_t _heap_used;
898 size_t _young_gen_used;
899 size_t _old_gen_used;
900 size_t _perm_gen_used;
901 };
902
903 void
904 PSParallelCompact::clear_data_covering_space(SpaceId id)
905 {
906 // At this point, top is the value before GC, new_top() is the value that will
907 // be set at the end of GC. The marking bitmap is cleared to top; nothing
908 // should be marked above top. The summary data is cleared to the larger of
909 // top & new_top.
910 MutableSpace* const space = _space_info[id].space();
911 HeapWord* const bot = space->bottom();
912 HeapWord* const top = space->top();
913 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
914
915 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
916 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
917 _mark_bitmap.clear_range(beg_bit, end_bit);
918
919 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
920 const size_t end_region =
921 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
922 _summary_data.clear_range(beg_region, end_region);
923
924 // Clear the data used to 'split' regions.
925 SplitInfo& split_info = _space_info[id].split_info();
926 if (split_info.is_valid()) {
927 split_info.clear();
928 }
929 DEBUG_ONLY(split_info.verify_clear();)
930 }
931
932 void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values)
933 {
934 // Update the from & to space pointers in space_info, since they are swapped
935 // at each young gen gc. Do the update unconditionally (even though a
936 // promotion failure does not swap spaces) because an unknown number of minor
937 // collections will have swapped the spaces an unknown number of times.
938 TraceTime tm("pre compact", print_phases(), true, gclog_or_tty);
939 ParallelScavengeHeap* heap = gc_heap();
940 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
941 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
942
943 pre_gc_values->fill(heap);
944
945 ParCompactionManager::reset();
946 NOT_PRODUCT(_mark_bitmap.reset_counters());
947 DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
948 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
949
950 // Increment the invocation count
951 heap->increment_total_collections(true);
952
953 // We need to track unique mark sweep invocations as well.
954 _total_invocations++;
955
956 if (PrintHeapAtGC) {
957 Universe::print_heap_before_gc();
958 }
959
960 // Fill in TLABs
961 heap->accumulate_statistics_all_tlabs();
962 heap->ensure_parsability(true); // retire TLABs
963
964 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
965 HandleMark hm; // Discard invalid handles created during verification
966 gclog_or_tty->print(" VerifyBeforeGC:");
967 Universe::verify(true);
968 }
969
970 // Verify object start arrays
971 if (VerifyObjectStartArray &&
972 VerifyBeforeGC) {
973 heap->old_gen()->verify_object_start_array();
974 heap->perm_gen()->verify_object_start_array();
975 }
976
977 DEBUG_ONLY(mark_bitmap()->verify_clear();)
978 DEBUG_ONLY(summary_data().verify_clear();)
979
980 // Have worker threads release resources the next time they run a task.
981 gc_task_manager()->release_all_resources();
982 }
983
984 void PSParallelCompact::post_compact()
985 {
986 TraceTime tm("post compact", print_phases(), true, gclog_or_tty);
987
988 for (unsigned int id = perm_space_id; id < last_space_id; ++id) {
989 // Clear the marking bitmap, summary data and split info.
990 clear_data_covering_space(SpaceId(id));
991 // Update top(). Must be done after clearing the bitmap and summary data.
992 _space_info[id].publish_new_top();
993 }
994
995 MutableSpace* const eden_space = _space_info[eden_space_id].space();
996 MutableSpace* const from_space = _space_info[from_space_id].space();
997 MutableSpace* const to_space = _space_info[to_space_id].space();
998
999 ParallelScavengeHeap* heap = gc_heap();
1000 bool eden_empty = eden_space->is_empty();
1001 if (!eden_empty) {
1002 eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1003 heap->young_gen(), heap->old_gen());
1004 }
1005
1006 // Update heap occupancy information which is used as input to the soft ref
1007 // clearing policy at the next gc.
1008 Universe::update_heap_info_at_gc();
1009
1010 bool young_gen_empty = eden_empty && from_space->is_empty() &&
1011 to_space->is_empty();
1012
1013 BarrierSet* bs = heap->barrier_set();
1014 if (bs->is_a(BarrierSet::ModRef)) {
1015 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
1016 MemRegion old_mr = heap->old_gen()->reserved();
1017 MemRegion perm_mr = heap->perm_gen()->reserved();
1018 assert(perm_mr.end() <= old_mr.start(), "Generations out of order");
1019
1020 if (young_gen_empty) {
1021 modBS->clear(MemRegion(perm_mr.start(), old_mr.end()));
1022 } else {
1023 modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end()));
1024 }
1025 }
1026
1027 Threads::gc_epilogue();
1028 CodeCache::gc_epilogue();
1029
1030 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1031
1032 ref_processor()->enqueue_discovered_references(NULL);
1033
1034 if (ZapUnusedHeapArea) {
1035 heap->gen_mangle_unused_area();
1036 }
1037
1038 // Update time of last GC
1039 reset_millis_since_last_gc();
1040 }
1041
1042 HeapWord*
1043 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1044 bool maximum_compaction)
1045 {
1046 const size_t region_size = ParallelCompactData::RegionSize;
1047 const ParallelCompactData& sd = summary_data();
1048
1049 const MutableSpace* const space = _space_info[id].space();
1050 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1051 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1052 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1053
1054 // Skip full regions at the beginning of the space--they are necessarily part
1055 // of the dense prefix.
1056 size_t full_count = 0;
1057 const RegionData* cp;
1058 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1059 ++full_count;
1060 }
1061
1062 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1063 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1064 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1065 if (maximum_compaction || cp == end_cp || interval_ended) {
1066 _maximum_compaction_gc_num = total_invocations();
1067 return sd.region_to_addr(cp);
1068 }
1069
1070 HeapWord* const new_top = _space_info[id].new_top();
1071 const size_t space_live = pointer_delta(new_top, space->bottom());
1072 const size_t space_used = space->used_in_words();
1073 const size_t space_capacity = space->capacity_in_words();
1074
1075 const double cur_density = double(space_live) / space_capacity;
1076 const double deadwood_density =
1077 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1078 const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1079
1080 if (TraceParallelOldGCDensePrefix) {
1081 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1082 cur_density, deadwood_density, deadwood_goal);
1083 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1084 "space_cap=" SIZE_FORMAT,
1085 space_live, space_used,
1086 space_capacity);
1087 }
1088
1089 // XXX - Use binary search?
1090 HeapWord* dense_prefix = sd.region_to_addr(cp);
1091 const RegionData* full_cp = cp;
1092 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1093 while (cp < end_cp) {
1094 HeapWord* region_destination = cp->destination();
1095 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1096 if (TraceParallelOldGCDensePrefix && Verbose) {
1097 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1098 "dp=" SIZE_FORMAT_W(8) " " "cdw=" SIZE_FORMAT_W(8),
1099 sd.region(cp), region_destination,
1100 dense_prefix, cur_deadwood);
1101 }
1102
1103 if (cur_deadwood >= deadwood_goal) {
1104 // Found the region that has the correct amount of deadwood to the left.
1105 // This typically occurs after crossing a fairly sparse set of regions, so
1106 // iterate backwards over those sparse regions, looking for the region
1107 // that has the lowest density of live objects 'to the right.'
1108 size_t space_to_left = sd.region(cp) * region_size;
1109 size_t live_to_left = space_to_left - cur_deadwood;
1110 size_t space_to_right = space_capacity - space_to_left;
1111 size_t live_to_right = space_live - live_to_left;
1112 double density_to_right = double(live_to_right) / space_to_right;
1113 while (cp > full_cp) {
1114 --cp;
1115 const size_t prev_region_live_to_right = live_to_right -
1116 cp->data_size();
1117 const size_t prev_region_space_to_right = space_to_right + region_size;
1118 double prev_region_density_to_right =
1119 double(prev_region_live_to_right) / prev_region_space_to_right;
1120 if (density_to_right <= prev_region_density_to_right) {
1121 return dense_prefix;
1122 }
1123 if (TraceParallelOldGCDensePrefix && Verbose) {
1124 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1125 "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1126 prev_region_density_to_right);
1127 }
1128 dense_prefix -= region_size;
1129 live_to_right = prev_region_live_to_right;
1130 space_to_right = prev_region_space_to_right;
1131 density_to_right = prev_region_density_to_right;
1132 }
1133 return dense_prefix;
1134 }
1135
1136 dense_prefix += region_size;
1137 ++cp;
1138 }
1139
1140 return dense_prefix;
1141 }
1142
1143 #ifndef PRODUCT
1144 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1145 const SpaceId id,
1146 const bool maximum_compaction,
1147 HeapWord* const addr)
1148 {
1149 const size_t region_idx = summary_data().addr_to_region_idx(addr);
1150 RegionData* const cp = summary_data().region(region_idx);
1151 const MutableSpace* const space = _space_info[id].space();
1152 HeapWord* const new_top = _space_info[id].new_top();
1153
1154 const size_t space_live = pointer_delta(new_top, space->bottom());
1155 const size_t dead_to_left = pointer_delta(addr, cp->destination());
1156 const size_t space_cap = space->capacity_in_words();
1157 const double dead_to_left_pct = double(dead_to_left) / space_cap;
1158 const size_t live_to_right = new_top - cp->destination();
1159 const size_t dead_to_right = space->top() - addr - live_to_right;
1160
1161 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1162 "spl=" SIZE_FORMAT " "
1163 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1164 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1165 " ratio=%10.8f",
1166 algorithm, addr, region_idx,
1167 space_live,
1168 dead_to_left, dead_to_left_pct,
1169 dead_to_right, live_to_right,
1170 double(dead_to_right) / live_to_right);
1171 }
1172 #endif // #ifndef PRODUCT
1173
1174 // Return a fraction indicating how much of the generation can be treated as
1175 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution
1176 // based on the density of live objects in the generation to determine a limit,
1177 // which is then adjusted so the return value is min_percent when the density is
1178 // 1.
1179 //
1180 // The following table shows some return values for a different values of the
1181 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1182 // min_percent is 1.
1183 //
1184 // fraction allowed as dead wood
1185 // -----------------------------------------------------------------
1186 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1187 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1188 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1189 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1190 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1191 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1192 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1193 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1194 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1195 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1196 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1197 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1198 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1199 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1200 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1201 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1202 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1203 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1204 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1205 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1206 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1207 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1208 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1209
1210 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1211 {
1212 assert(_dwl_initialized, "uninitialized");
1213
1214 // The raw limit is the value of the normal distribution at x = density.
1215 const double raw_limit = normal_distribution(density);
1216
1217 // Adjust the raw limit so it becomes the minimum when the density is 1.
1218 //
1219 // First subtract the adjustment value (which is simply the precomputed value
1220 // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1221 // Then add the minimum value, so the minimum is returned when the density is
1222 // 1. Finally, prevent negative values, which occur when the mean is not 0.5.
1223 const double min = double(min_percent) / 100.0;
1224 const double limit = raw_limit - _dwl_adjustment + min;
1225 return MAX2(limit, 0.0);
1226 }
1227
1228 ParallelCompactData::RegionData*
1229 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1230 const RegionData* end)
1231 {
1232 const size_t region_size = ParallelCompactData::RegionSize;
1233 ParallelCompactData& sd = summary_data();
1234 size_t left = sd.region(beg);
1235 size_t right = end > beg ? sd.region(end) - 1 : left;
1236
1237 // Binary search.
1238 while (left < right) {
1239 // Equivalent to (left + right) / 2, but does not overflow.
1240 const size_t middle = left + (right - left) / 2;
1241 RegionData* const middle_ptr = sd.region(middle);
1242 HeapWord* const dest = middle_ptr->destination();
1243 HeapWord* const addr = sd.region_to_addr(middle);
1244 assert(dest != NULL, "sanity");
1245 assert(dest <= addr, "must move left");
1246
1247 if (middle > left && dest < addr) {
1248 right = middle - 1;
1249 } else if (middle < right && middle_ptr->data_size() == region_size) {
1250 left = middle + 1;
1251 } else {
1252 return middle_ptr;
1253 }
1254 }
1255 return sd.region(left);
1256 }
1257
1258 ParallelCompactData::RegionData*
1259 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1260 const RegionData* end,
1261 size_t dead_words)
1262 {
1263 ParallelCompactData& sd = summary_data();
1264 size_t left = sd.region(beg);
1265 size_t right = end > beg ? sd.region(end) - 1 : left;
1266
1267 // Binary search.
1268 while (left < right) {
1269 // Equivalent to (left + right) / 2, but does not overflow.
1270 const size_t middle = left + (right - left) / 2;
1271 RegionData* const middle_ptr = sd.region(middle);
1272 HeapWord* const dest = middle_ptr->destination();
1273 HeapWord* const addr = sd.region_to_addr(middle);
1274 assert(dest != NULL, "sanity");
1275 assert(dest <= addr, "must move left");
1276
1277 const size_t dead_to_left = pointer_delta(addr, dest);
1278 if (middle > left && dead_to_left > dead_words) {
1279 right = middle - 1;
1280 } else if (middle < right && dead_to_left < dead_words) {
1281 left = middle + 1;
1282 } else {
1283 return middle_ptr;
1284 }
1285 }
1286 return sd.region(left);
1287 }
1288
1289 // The result is valid during the summary phase, after the initial summarization
1290 // of each space into itself, and before final summarization.
1291 inline double
1292 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1293 HeapWord* const bottom,
1294 HeapWord* const top,
1295 HeapWord* const new_top)
1296 {
1297 ParallelCompactData& sd = summary_data();
1298
1299 assert(cp != NULL, "sanity");
1300 assert(bottom != NULL, "sanity");
1301 assert(top != NULL, "sanity");
1302 assert(new_top != NULL, "sanity");
1303 assert(top >= new_top, "summary data problem?");
1304 assert(new_top > bottom, "space is empty; should not be here");
1305 assert(new_top >= cp->destination(), "sanity");
1306 assert(top >= sd.region_to_addr(cp), "sanity");
1307
1308 HeapWord* const destination = cp->destination();
1309 const size_t dense_prefix_live = pointer_delta(destination, bottom);
1310 const size_t compacted_region_live = pointer_delta(new_top, destination);
1311 const size_t compacted_region_used = pointer_delta(top,
1312 sd.region_to_addr(cp));
1313 const size_t reclaimable = compacted_region_used - compacted_region_live;
1314
1315 const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1316 return double(reclaimable) / divisor;
1317 }
1318
1319 // Return the address of the end of the dense prefix, a.k.a. the start of the
1320 // compacted region. The address is always on a region boundary.
1321 //
1322 // Completely full regions at the left are skipped, since no compaction can
1323 // occur in those regions. Then the maximum amount of dead wood to allow is
1324 // computed, based on the density (amount live / capacity) of the generation;
1325 // the region with approximately that amount of dead space to the left is
1326 // identified as the limit region. Regions between the last completely full
1327 // region and the limit region are scanned and the one that has the best
1328 // (maximum) reclaimed_ratio() is selected.
1329 HeapWord*
1330 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1331 bool maximum_compaction)
1332 {
1333 if (ParallelOldGCSplitALot) {
1334 if (_space_info[id].dense_prefix() != _space_info[id].space()->bottom()) {
1335 // The value was chosen to provoke splitting a young gen space; use it.
1336 return _space_info[id].dense_prefix();
1337 }
1338 }
1339
1340 const size_t region_size = ParallelCompactData::RegionSize;
1341 const ParallelCompactData& sd = summary_data();
1342
1343 const MutableSpace* const space = _space_info[id].space();
1344 HeapWord* const top = space->top();
1345 HeapWord* const top_aligned_up = sd.region_align_up(top);
1346 HeapWord* const new_top = _space_info[id].new_top();
1347 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1348 HeapWord* const bottom = space->bottom();
1349 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1350 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1351 const RegionData* const new_top_cp =
1352 sd.addr_to_region_ptr(new_top_aligned_up);
1353
1354 // Skip full regions at the beginning of the space--they are necessarily part
1355 // of the dense prefix.
1356 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1357 assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1358 space->is_empty(), "no dead space allowed to the left");
1359 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1360 "region must have dead space");
1361
1362 // The gc number is saved whenever a maximum compaction is done, and used to
1363 // determine when the maximum compaction interval has expired. This avoids
1364 // successive max compactions for different reasons.
1365 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1366 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1367 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1368 total_invocations() == HeapFirstMaximumCompactionCount;
1369 if (maximum_compaction || full_cp == top_cp || interval_ended) {
1370 _maximum_compaction_gc_num = total_invocations();
1371 return sd.region_to_addr(full_cp);
1372 }
1373
1374 const size_t space_live = pointer_delta(new_top, bottom);
1375 const size_t space_used = space->used_in_words();
1376 const size_t space_capacity = space->capacity_in_words();
1377
1378 const double density = double(space_live) / double(space_capacity);
1379 const size_t min_percent_free =
1380 id == perm_space_id ? PermMarkSweepDeadRatio : MarkSweepDeadRatio;
1381 const double limiter = dead_wood_limiter(density, min_percent_free);
1382 const size_t dead_wood_max = space_used - space_live;
1383 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1384 dead_wood_max);
1385
1386 if (TraceParallelOldGCDensePrefix) {
1387 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1388 "space_cap=" SIZE_FORMAT,
1389 space_live, space_used,
1390 space_capacity);
1391 tty->print_cr("dead_wood_limiter(%6.4f, %d)=%6.4f "
1392 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1393 density, min_percent_free, limiter,
1394 dead_wood_max, dead_wood_limit);
1395 }
1396
1397 // Locate the region with the desired amount of dead space to the left.
1398 const RegionData* const limit_cp =
1399 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1400
1401 // Scan from the first region with dead space to the limit region and find the
1402 // one with the best (largest) reclaimed ratio.
1403 double best_ratio = 0.0;
1404 const RegionData* best_cp = full_cp;
1405 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1406 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1407 if (tmp_ratio > best_ratio) {
1408 best_cp = cp;
1409 best_ratio = tmp_ratio;
1410 }
1411 }
1412
1413 #if 0
1414 // Something to consider: if the region with the best ratio is 'close to' the
1415 // first region w/free space, choose the first region with free space
1416 // ("first-free"). The first-free region is usually near the start of the
1417 // heap, which means we are copying most of the heap already, so copy a bit
1418 // more to get complete compaction.
1419 if (pointer_delta(best_cp, full_cp, sizeof(RegionData)) < 4) {
1420 _maximum_compaction_gc_num = total_invocations();
1421 best_cp = full_cp;
1422 }
1423 #endif // #if 0
1424
1425 return sd.region_to_addr(best_cp);
1426 }
1427
1428 #ifndef PRODUCT
1429 void
1430 PSParallelCompact::fill_with_live_objects(SpaceId id, HeapWord* const start,
1431 size_t words)
1432 {
1433 if (TraceParallelOldGCSummaryPhase) {
1434 tty->print_cr("fill_with_live_objects [" PTR_FORMAT " " PTR_FORMAT ") "
1435 SIZE_FORMAT, start, start + words, words);
1436 }
1437
1438 ObjectStartArray* const start_array = _space_info[id].start_array();
1439 CollectedHeap::fill_with_objects(start, words);
1440 for (HeapWord* p = start; p < start + words; p += oop(p)->size()) {
1441 _mark_bitmap.mark_obj(p, words);
1442 _summary_data.add_obj(p, words);
1443 start_array->allocate_block(p);
1444 }
1445 }
1446
1447 void
1448 PSParallelCompact::summarize_new_objects(SpaceId id, HeapWord* start)
1449 {
1450 ParallelCompactData& sd = summary_data();
1451 MutableSpace* space = _space_info[id].space();
1452
1453 // Find the source and destination start addresses.
1454 HeapWord* const src_addr = sd.region_align_down(start);
1455 HeapWord* dst_addr;
1456 if (src_addr < start) {
1457 dst_addr = sd.addr_to_region_ptr(src_addr)->destination();
1458 } else if (src_addr > space->bottom()) {
1459 // The start (the original top() value) is aligned to a region boundary so
1460 // the associated region does not have a destination. Compute the
1461 // destination from the previous region.
1462 RegionData* const cp = sd.addr_to_region_ptr(src_addr) - 1;
1463 dst_addr = cp->destination() + cp->data_size();
1464 } else {
1465 // Filling the entire space.
1466 dst_addr = space->bottom();
1467 }
1468 assert(dst_addr != NULL, "sanity");
1469
1470 // Update the summary data.
1471 bool result = _summary_data.summarize(_space_info[id].split_info(),
1472 src_addr, space->top(), NULL,
1473 dst_addr, space->end(),
1474 _space_info[id].new_top_addr());
1475 assert(result, "should not fail: bad filler object size");
1476 }
1477
1478 void
1479 PSParallelCompact::provoke_split_fill_survivor(SpaceId id)
1480 {
1481 if (total_invocations() % (ParallelOldGCSplitInterval * 3) != 0) {
1482 return;
1483 }
1484
1485 MutableSpace* const space = _space_info[id].space();
1486 if (space->is_empty()) {
1487 HeapWord* b = space->bottom();
1488 HeapWord* t = b + space->capacity_in_words() / 2;
1489 space->set_top(t);
1490 if (ZapUnusedHeapArea) {
1491 space->set_top_for_allocations();
1492 }
1493
1494 size_t obj_len = 8;
1495 while (b + obj_len <= t) {
1496 CollectedHeap::fill_with_object(b, obj_len);
1497 mark_bitmap()->mark_obj(b, obj_len);
1498 summary_data().add_obj(b, obj_len);
1499 b += obj_len;
1500 obj_len = (obj_len & 0x18) + 8; // 8 16 24 32 8 16 24 32 ...
1501 }
1502 if (b < t) {
1503 // The loop didn't completely fill to t (top); adjust top downward.
1504 space->set_top(b);
1505 if (ZapUnusedHeapArea) {
1506 space->set_top_for_allocations();
1507 }
1508 }
1509
1510 HeapWord** nta = _space_info[id].new_top_addr();
1511 bool result = summary_data().summarize(_space_info[id].split_info(),
1512 space->bottom(), space->top(), NULL,
1513 space->bottom(), space->end(), nta);
1514 assert(result, "space must fit into itself");
1515 }
1516 }
1517
1518 void
1519 PSParallelCompact::provoke_split(bool & max_compaction)
1520 {
1521 if (total_invocations() % ParallelOldGCSplitInterval != 0) {
1522 return;
1523 }
1524
1525 const size_t region_size = ParallelCompactData::RegionSize;
1526 ParallelCompactData& sd = summary_data();
1527
1528 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1529 MutableSpace* const from_space = _space_info[from_space_id].space();
1530 const size_t eden_live = pointer_delta(eden_space->top(),
1531 _space_info[eden_space_id].new_top());
1532 const size_t from_live = pointer_delta(from_space->top(),
1533 _space_info[from_space_id].new_top());
1534
1535 const size_t min_fill_size = CollectedHeap::min_fill_size();
1536 const size_t eden_free = pointer_delta(eden_space->end(), eden_space->top());
1537 const size_t eden_fillable = eden_free >= min_fill_size ? eden_free : 0;
1538 const size_t from_free = pointer_delta(from_space->end(), from_space->top());
1539 const size_t from_fillable = from_free >= min_fill_size ? from_free : 0;
1540
1541 // Choose the space to split; need at least 2 regions live (or fillable).
1542 SpaceId id;
1543 MutableSpace* space;
1544 size_t live_words;
1545 size_t fill_words;
1546 if (eden_live + eden_fillable >= region_size * 2) {
1547 id = eden_space_id;
1548 space = eden_space;
1549 live_words = eden_live;
1550 fill_words = eden_fillable;
1551 } else if (from_live + from_fillable >= region_size * 2) {
1552 id = from_space_id;
1553 space = from_space;
1554 live_words = from_live;
1555 fill_words = from_fillable;
1556 } else {
1557 return; // Give up.
1558 }
1559 assert(fill_words == 0 || fill_words >= min_fill_size, "sanity");
1560
1561 if (live_words < region_size * 2) {
1562 // Fill from top() to end() w/live objects of mixed sizes.
1563 HeapWord* const fill_start = space->top();
1564 live_words += fill_words;
1565
1566 space->set_top(fill_start + fill_words);
1567 if (ZapUnusedHeapArea) {
1568 space->set_top_for_allocations();
1569 }
1570
1571 HeapWord* cur_addr = fill_start;
1572 while (fill_words > 0) {
1573 const size_t r = (size_t)os::random() % (region_size / 2) + min_fill_size;
1574 size_t cur_size = MIN2(align_object_size_(r), fill_words);
1575 if (fill_words - cur_size < min_fill_size) {
1576 cur_size = fill_words; // Avoid leaving a fragment too small to fill.
1577 }
1578
1579 CollectedHeap::fill_with_object(cur_addr, cur_size);
1580 mark_bitmap()->mark_obj(cur_addr, cur_size);
1581 sd.add_obj(cur_addr, cur_size);
1582
1583 cur_addr += cur_size;
1584 fill_words -= cur_size;
1585 }
1586
1587 summarize_new_objects(id, fill_start);
1588 }
1589
1590 max_compaction = false;
1591
1592 // Manipulate the old gen so that it has room for about half of the live data
1593 // in the target young gen space (live_words / 2).
1594 id = old_space_id;
1595 space = _space_info[id].space();
1596 const size_t free_at_end = space->free_in_words();
1597 const size_t free_target = align_object_size(live_words / 2);
1598 const size_t dead = pointer_delta(space->top(), _space_info[id].new_top());
1599
1600 if (free_at_end >= free_target + min_fill_size) {
1601 // Fill space above top() and set the dense prefix so everything survives.
1602 HeapWord* const fill_start = space->top();
1603 const size_t fill_size = free_at_end - free_target;
1604 space->set_top(space->top() + fill_size);
1605 if (ZapUnusedHeapArea) {
1606 space->set_top_for_allocations();
1607 }
1608 fill_with_live_objects(id, fill_start, fill_size);
1609 summarize_new_objects(id, fill_start);
1610 _space_info[id].set_dense_prefix(sd.region_align_down(space->top()));
1611 } else if (dead + free_at_end > free_target) {
1612 // Find a dense prefix that makes the right amount of space available.
1613 HeapWord* cur = sd.region_align_down(space->top());
1614 HeapWord* cur_destination = sd.addr_to_region_ptr(cur)->destination();
1615 size_t dead_to_right = pointer_delta(space->end(), cur_destination);
1616 while (dead_to_right < free_target) {
1617 cur -= region_size;
1618 cur_destination = sd.addr_to_region_ptr(cur)->destination();
1619 dead_to_right = pointer_delta(space->end(), cur_destination);
1620 }
1621 _space_info[id].set_dense_prefix(cur);
1622 }
1623 }
1624 #endif // #ifndef PRODUCT
1625
1626 void PSParallelCompact::summarize_spaces_quick()
1627 {
1628 for (unsigned int i = 0; i < last_space_id; ++i) {
1629 const MutableSpace* space = _space_info[i].space();
1630 HeapWord** nta = _space_info[i].new_top_addr();
1631 bool result = _summary_data.summarize(_space_info[i].split_info(),
1632 space->bottom(), space->top(), NULL,
1633 space->bottom(), space->end(), nta);
1634 assert(result, "space must fit into itself");
1635 _space_info[i].set_dense_prefix(space->bottom());
1636 }
1637
1638 #ifndef PRODUCT
1639 if (ParallelOldGCSplitALot) {
1640 provoke_split_fill_survivor(to_space_id);
1641 }
1642 #endif // #ifndef PRODUCT
1643 }
1644
1645 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1646 {
1647 HeapWord* const dense_prefix_end = dense_prefix(id);
1648 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1649 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1650 if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1651 // Only enough dead space is filled so that any remaining dead space to the
1652 // left is larger than the minimum filler object. (The remainder is filled
1653 // during the copy/update phase.)
1654 //
1655 // The size of the dead space to the right of the boundary is not a
1656 // concern, since compaction will be able to use whatever space is
1657 // available.
1658 //
1659 // Here '||' is the boundary, 'x' represents a don't care bit and a box
1660 // surrounds the space to be filled with an object.
1661 //
1662 // In the 32-bit VM, each bit represents two 32-bit words:
1663 // +---+
1664 // a) beg_bits: ... x x x | 0 | || 0 x x ...
1665 // end_bits: ... x x x | 0 | || 0 x x ...
1666 // +---+
1667 //
1668 // In the 64-bit VM, each bit represents one 64-bit word:
1669 // +------------+
1670 // b) beg_bits: ... x x x | 0 || 0 | x x ...
1671 // end_bits: ... x x 1 | 0 || 0 | x x ...
1672 // +------------+
1673 // +-------+
1674 // c) beg_bits: ... x x | 0 0 | || 0 x x ...
1675 // end_bits: ... x 1 | 0 0 | || 0 x x ...
1676 // +-------+
1677 // +-----------+
1678 // d) beg_bits: ... x | 0 0 0 | || 0 x x ...
1679 // end_bits: ... 1 | 0 0 0 | || 0 x x ...
1680 // +-----------+
1681 // +-------+
1682 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ...
1683 // end_bits: ... 0 0 | 0 0 | || 0 x x ...
1684 // +-------+
1685
1686 // Initially assume case a, c or e will apply.
1687 size_t obj_len = (size_t)oopDesc::header_size();
1688 HeapWord* obj_beg = dense_prefix_end - obj_len;
1689
1690 #ifdef _LP64
1691 if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1692 // Case b above.
1693 obj_beg = dense_prefix_end - 1;
1694 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1695 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1696 // Case d above.
1697 obj_beg = dense_prefix_end - 3;
1698 obj_len = 3;
1699 }
1700 #endif // #ifdef _LP64
1701
1702 CollectedHeap::fill_with_object(obj_beg, obj_len);
1703 _mark_bitmap.mark_obj(obj_beg, obj_len);
1704 _summary_data.add_obj(obj_beg, obj_len);
1705 assert(start_array(id) != NULL, "sanity");
1706 start_array(id)->allocate_block(obj_beg);
1707 }
1708 }
1709
1710 void
1711 PSParallelCompact::clear_source_region(HeapWord* beg_addr, HeapWord* end_addr)
1712 {
1713 RegionData* const beg_ptr = _summary_data.addr_to_region_ptr(beg_addr);
1714 HeapWord* const end_aligned_up = _summary_data.region_align_up(end_addr);
1715 RegionData* const end_ptr = _summary_data.addr_to_region_ptr(end_aligned_up);
1716 for (RegionData* cur = beg_ptr; cur < end_ptr; ++cur) {
1717 cur->set_source_region(0);
1718 }
1719 }
1720
1721 void
1722 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1723 {
1724 assert(id < last_space_id, "id out of range");
1725 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom() ||
1726 ParallelOldGCSplitALot && id == old_space_id,
1727 "should have been reset in summarize_spaces_quick()");
1728
1729 const MutableSpace* space = _space_info[id].space();
1730 if (_space_info[id].new_top() != space->bottom()) {
1731 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1732 _space_info[id].set_dense_prefix(dense_prefix_end);
1733
1734 #ifndef PRODUCT
1735 if (TraceParallelOldGCDensePrefix) {
1736 print_dense_prefix_stats("ratio", id, maximum_compaction,
1737 dense_prefix_end);
1738 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1739 print_dense_prefix_stats("density", id, maximum_compaction, addr);
1740 }
1741 #endif // #ifndef PRODUCT
1742
1743 // Recompute the summary data, taking into account the dense prefix. If
1744 // every last byte will be reclaimed, then the existing summary data which
1745 // compacts everything can be left in place.
1746 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1747 // If dead space crosses the dense prefix boundary, it is (at least
1748 // partially) filled with a dummy object, marked live and added to the
1749 // summary data. This simplifies the copy/update phase and must be done
1750 // before the final locations of objects are determined, to prevent
1751 // leaving a fragment of dead space that is too small to fill.
1752 fill_dense_prefix_end(id);
1753
1754 // Compute the destination of each Region, and thus each object.
1755 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1756 _summary_data.summarize(_space_info[id].split_info(),
1757 dense_prefix_end, space->top(), NULL,
1758 dense_prefix_end, space->end(),
1759 _space_info[id].new_top_addr());
1760 }
1761 }
1762
1763 if (TraceParallelOldGCSummaryPhase) {
1764 const size_t region_size = ParallelCompactData::RegionSize;
1765 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1766 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1767 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1768 HeapWord* const new_top = _space_info[id].new_top();
1769 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1770 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1771 tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1772 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1773 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1774 id, space->capacity_in_words(), dense_prefix_end,
1775 dp_region, dp_words / region_size,
1776 cr_words / region_size, new_top);
1777 }
1778 }
1779
1780 #ifndef PRODUCT
1781 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1782 HeapWord* dst_beg, HeapWord* dst_end,
1783 SpaceId src_space_id,
1784 HeapWord* src_beg, HeapWord* src_end)
1785 {
1786 if (TraceParallelOldGCSummaryPhase) {
1787 tty->print_cr("summarizing %d [%s] into %d [%s]: "
1788 "src=" PTR_FORMAT "-" PTR_FORMAT " "
1789 SIZE_FORMAT "-" SIZE_FORMAT " "
1790 "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1791 SIZE_FORMAT "-" SIZE_FORMAT,
1792 src_space_id, space_names[src_space_id],
1793 dst_space_id, space_names[dst_space_id],
1794 src_beg, src_end,
1795 _summary_data.addr_to_region_idx(src_beg),
1796 _summary_data.addr_to_region_idx(src_end),
1797 dst_beg, dst_end,
1798 _summary_data.addr_to_region_idx(dst_beg),
1799 _summary_data.addr_to_region_idx(dst_end));
1800 }
1801 }
1802 #endif // #ifndef PRODUCT
1803
1804 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1805 bool maximum_compaction)
1806 {
1807 EventMark m("2 summarize");
1808 TraceTime tm("summary phase", print_phases(), true, gclog_or_tty);
1809 // trace("2");
1810
1811 #ifdef ASSERT
1812 if (TraceParallelOldGCMarkingPhase) {
1813 tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1814 "add_obj_bytes=" SIZE_FORMAT,
1815 add_obj_count, add_obj_size * HeapWordSize);
1816 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1817 "mark_bitmap_bytes=" SIZE_FORMAT,
1818 mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1819 }
1820 #endif // #ifdef ASSERT
1821
1822 // Quick summarization of each space into itself, to see how much is live.
1823 summarize_spaces_quick();
1824
1825 if (TraceParallelOldGCSummaryPhase) {
1826 tty->print_cr("summary_phase: after summarizing each space to self");
1827 Universe::print();
1828 NOT_PRODUCT(print_region_ranges());
1829 if (Verbose) {
1830 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1831 }
1832 }
1833
1834 // The amount of live data that will end up in old space (assuming it fits).
1835 size_t old_space_total_live = 0;
1836 assert(perm_space_id < old_space_id, "should not count perm data here");
1837 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1838 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1839 _space_info[id].space()->bottom());
1840 }
1841
1842 MutableSpace* const old_space = _space_info[old_space_id].space();
1843 const size_t old_capacity = old_space->capacity_in_words();
1844 if (old_space_total_live > old_capacity) {
1845 // XXX - should also try to expand
1846 maximum_compaction = true;
1847 }
1848 #ifndef PRODUCT
1849 if (ParallelOldGCSplitALot && old_space_total_live < old_capacity) {
1850 provoke_split(maximum_compaction);
1851 }
1852 #endif // #ifndef PRODUCT
1853
1854 // Permanent and Old generations.
1855 summarize_space(perm_space_id, maximum_compaction);
1856 summarize_space(old_space_id, maximum_compaction);
1857
1858 // Summarize the remaining spaces in the young gen. The initial target space
1859 // is the old gen. If a space does not fit entirely into the target, then the
1860 // remainder is compacted into the space itself and that space becomes the new
1861 // target.
1862 SpaceId dst_space_id = old_space_id;
1863 HeapWord* dst_space_end = old_space->end();
1864 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1865 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1866 const MutableSpace* space = _space_info[id].space();
1867 const size_t live = pointer_delta(_space_info[id].new_top(),
1868 space->bottom());
1869 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1870
1871 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1872 SpaceId(id), space->bottom(), space->top());)
1873 if (live > 0 && live <= available) {
1874 // All the live data will fit.
1875 bool done = _summary_data.summarize(_space_info[id].split_info(),
1876 space->bottom(), space->top(),
1877 NULL,
1878 *new_top_addr, dst_space_end,
1879 new_top_addr);
1880 assert(done, "space must fit into old gen");
1881
1882 // Reset the new_top value for the space.
1883 _space_info[id].set_new_top(space->bottom());
1884 } else if (live > 0) {
1885 // Attempt to fit part of the source space into the target space.
1886 HeapWord* next_src_addr = NULL;
1887 bool done = _summary_data.summarize(_space_info[id].split_info(),
1888 space->bottom(), space->top(),
1889 &next_src_addr,
1890 *new_top_addr, dst_space_end,
1891 new_top_addr);
1892 assert(!done, "space should not fit into old gen");
1893 assert(next_src_addr != NULL, "sanity");
1894
1895 // The source space becomes the new target, so the remainder is compacted
1896 // within the space itself.
1897 dst_space_id = SpaceId(id);
1898 dst_space_end = space->end();
1899 new_top_addr = _space_info[id].new_top_addr();
1900 NOT_PRODUCT(summary_phase_msg(dst_space_id,
1901 space->bottom(), dst_space_end,
1902 SpaceId(id), next_src_addr, space->top());)
1903 done = _summary_data.summarize(_space_info[id].split_info(),
1904 next_src_addr, space->top(),
1905 NULL,
1906 space->bottom(), dst_space_end,
1907 new_top_addr);
1908 assert(done, "space must fit when compacted into itself");
1909 assert(*new_top_addr <= space->top(), "usage should not grow");
1910 }
1911 }
1912
1913 if (TraceParallelOldGCSummaryPhase) {
1914 tty->print_cr("summary_phase: after final summarization");
1915 Universe::print();
1916 NOT_PRODUCT(print_region_ranges());
1917 if (Verbose) {
1918 NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info));
1919 }
1920 }
1921 }
1922
1923 // This method should contain all heap-specific policy for invoking a full
1924 // collection. invoke_no_policy() will only attempt to compact the heap; it
1925 // will do nothing further. If we need to bail out for policy reasons, scavenge
1926 // before full gc, or any other specialized behavior, it needs to be added here.
1927 //
1928 // Note that this method should only be called from the vm_thread while at a
1929 // safepoint.
1930 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1931 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1932 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1933 "should be in vm thread");
1934 ParallelScavengeHeap* heap = gc_heap();
1935 GCCause::Cause gc_cause = heap->gc_cause();
1936 assert(!heap->is_gc_active(), "not reentrant");
1937
1938 PSAdaptiveSizePolicy* policy = heap->size_policy();
1939
1940 // Before each allocation/collection attempt, find out from the
1941 // policy object if GCs are, on the whole, taking too long. If so,
1942 // bail out without attempting a collection. The exceptions are
1943 // for explicitly requested GC's.
1944 if (!policy->gc_time_limit_exceeded() ||
1945 GCCause::is_user_requested_gc(gc_cause) ||
1946 GCCause::is_serviceability_requested_gc(gc_cause)) {
1947 IsGCActiveMark mark;
1948
1949 if (ScavengeBeforeFullGC) {
1950 PSScavenge::invoke_no_policy();
1951 }
1952
1953 PSParallelCompact::invoke_no_policy(maximum_heap_compaction);
1954 }
1955 }
1956
1957 bool ParallelCompactData::region_contains(size_t region_index, HeapWord* addr) {
1958 size_t addr_region_index = addr_to_region_idx(addr);
1959 return region_index == addr_region_index;
1960 }
1961
1962 // This method contains no policy. You should probably
1963 // be calling invoke() instead.
1964 void PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1965 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1966 assert(ref_processor() != NULL, "Sanity");
1967
1968 if (GC_locker::check_active_before_gc()) {
1969 return;
1970 }
1971
1972 TimeStamp marking_start;
1973 TimeStamp compaction_start;
1974 TimeStamp collection_exit;
1975
1976 ParallelScavengeHeap* heap = gc_heap();
1977 GCCause::Cause gc_cause = heap->gc_cause();
1978 PSYoungGen* young_gen = heap->young_gen();
1979 PSOldGen* old_gen = heap->old_gen();
1980 PSPermGen* perm_gen = heap->perm_gen();
1981 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1982
1983 if (ZapUnusedHeapArea) {
1984 // Save information needed to minimize mangling
1985 heap->record_gen_tops_before_GC();
1986 }
1987
1988 _print_phases = PrintGCDetails && PrintParallelOldGCPhaseTimes;
1989
1990 // Make sure data structures are sane, make the heap parsable, and do other
1991 // miscellaneous bookkeeping.
1992 PreGCValues pre_gc_values;
1993 pre_compact(&pre_gc_values);
1994
1995 // Get the compaction manager reserved for the VM thread.
1996 ParCompactionManager* const vmthread_cm =
1997 ParCompactionManager::manager_array(gc_task_manager()->workers());
1998
1999 // Place after pre_compact() where the number of invocations is incremented.
2000 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
2001
2002 {
2003 ResourceMark rm;
2004 HandleMark hm;
2005
2006 const bool is_system_gc = gc_cause == GCCause::_java_lang_system_gc;
2007
2008 // This is useful for debugging but don't change the output the
2009 // the customer sees.
2010 const char* gc_cause_str = "Full GC";
2011 if (is_system_gc && PrintGCDetails) {
2012 gc_cause_str = "Full GC (System)";
2013 }
2014 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2015 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2016 TraceTime t1(gc_cause_str, PrintGC, !PrintGCDetails, gclog_or_tty);
2017 TraceCollectorStats tcs(counters());
2018 TraceMemoryManagerStats tms(true /* Full GC */);
2019
2020 if (TraceGen1Time) accumulated_time()->start();
2021
2022 // Let the size policy know we're starting
2023 size_policy->major_collection_begin();
2024
2025 // When collecting the permanent generation methodOops may be moving,
2026 // so we either have to flush all bcp data or convert it into bci.
2027 CodeCache::gc_prologue();
2028 Threads::gc_prologue();
2029
2030 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
2031 COMPILER2_PRESENT(DerivedPointerTable::clear());
2032
2033 ref_processor()->enable_discovery();
2034 ref_processor()->setup_policy(maximum_heap_compaction);
2035
2036 bool marked_for_unloading = false;
2037
2038 marking_start.update();
2039 marking_phase(vmthread_cm, maximum_heap_compaction);
2040
2041 #ifndef PRODUCT
2042 if (TraceParallelOldGCMarkingPhase) {
2043 gclog_or_tty->print_cr("marking_phase: cas_tries %d cas_retries %d "
2044 "cas_by_another %d",
2045 mark_bitmap()->cas_tries(), mark_bitmap()->cas_retries(),
2046 mark_bitmap()->cas_by_another());
2047 }
2048 #endif // #ifndef PRODUCT
2049
2050 bool max_on_system_gc = UseMaximumCompactionOnSystemGC && is_system_gc;
2051 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
2052
2053 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
2054 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
2055
2056 // adjust_roots() updates Universe::_intArrayKlassObj which is
2057 // needed by the compaction for filling holes in the dense prefix.
2058 adjust_roots();
2059
2060 compaction_start.update();
2061 // Does the perm gen always have to be done serially because
2062 // klasses are used in the update of an object?
2063 compact_perm(vmthread_cm);
2064
2065 if (UseParallelOldGCCompacting) {
2066 compact();
2067 } else {
2068 compact_serial(vmthread_cm);
2069 }
2070
2071 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
2072 // done before resizing.
2073 post_compact();
2074
2075 // Let the size policy know we're done
2076 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
2077
2078 if (UseAdaptiveSizePolicy) {
2079 if (PrintAdaptiveSizePolicy) {
2080 gclog_or_tty->print("AdaptiveSizeStart: ");
2081 gclog_or_tty->stamp();
2082 gclog_or_tty->print_cr(" collection: %d ",
2083 heap->total_collections());
2084 if (Verbose) {
2085 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d"
2086 " perm_gen_capacity: %d ",
2087 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),
2088 perm_gen->capacity_in_bytes());
2089 }
2090 }
2091
2092 // Don't check if the size_policy is ready here. Let
2093 // the size_policy check that internally.
2094 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
2095 ((gc_cause != GCCause::_java_lang_system_gc) ||
2096 UseAdaptiveSizePolicyWithSystemGC)) {
2097 // Calculate optimal free space amounts
2098 assert(young_gen->max_size() >
2099 young_gen->from_space()->capacity_in_bytes() +
2100 young_gen->to_space()->capacity_in_bytes(),
2101 "Sizes of space in young gen are out-of-bounds");
2102 size_t max_eden_size = young_gen->max_size() -
2103 young_gen->from_space()->capacity_in_bytes() -
2104 young_gen->to_space()->capacity_in_bytes();
2105 size_policy->compute_generation_free_space(
2106 young_gen->used_in_bytes(),
2107 young_gen->eden_space()->used_in_bytes(),
2108 old_gen->used_in_bytes(),
2109 perm_gen->used_in_bytes(),
2110 young_gen->eden_space()->capacity_in_bytes(),
2111 old_gen->max_gen_size(),
2112 max_eden_size,
2113 true /* full gc*/,
2114 gc_cause);
2115
2116 heap->resize_old_gen(
2117 size_policy->calculated_old_free_size_in_bytes());
2118
2119 // Don't resize the young generation at an major collection. A
2120 // desired young generation size may have been calculated but
2121 // resizing the young generation complicates the code because the
2122 // resizing of the old generation may have moved the boundary
2123 // between the young generation and the old generation. Let the
2124 // young generation resizing happen at the minor collections.
2125 }
2126 if (PrintAdaptiveSizePolicy) {
2127 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
2128 heap->total_collections());
2129 }
2130 }
2131
2132 if (UsePerfData) {
2133 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
2134 counters->update_counters();
2135 counters->update_old_capacity(old_gen->capacity_in_bytes());
2136 counters->update_young_capacity(young_gen->capacity_in_bytes());
2137 }
2138
2139 heap->resize_all_tlabs();
2140
2141 // We collected the perm gen, so we'll resize it here.
2142 perm_gen->compute_new_size(pre_gc_values.perm_gen_used());
2143
2144 if (TraceGen1Time) accumulated_time()->stop();
2145
2146 if (PrintGC) {
2147 if (PrintGCDetails) {
2148 // No GC timestamp here. This is after GC so it would be confusing.
2149 young_gen->print_used_change(pre_gc_values.young_gen_used());
2150 old_gen->print_used_change(pre_gc_values.old_gen_used());
2151 heap->print_heap_change(pre_gc_values.heap_used());
2152 // Print perm gen last (print_heap_change() excludes the perm gen).
2153 perm_gen->print_used_change(pre_gc_values.perm_gen_used());
2154 } else {
2155 heap->print_heap_change(pre_gc_values.heap_used());
2156 }
2157 }
2158
2159 // Track memory usage and detect low memory
2160 MemoryService::track_memory_usage();
2161 heap->update_counters();
2162
2163 if (PrintGCDetails) {
2164 if (size_policy->print_gc_time_limit_would_be_exceeded()) {
2165 if (size_policy->gc_time_limit_exceeded()) {
2166 gclog_or_tty->print_cr(" GC time is exceeding GCTimeLimit "
2167 "of %d%%", GCTimeLimit);
2168 } else {
2169 gclog_or_tty->print_cr(" GC time would exceed GCTimeLimit "
2170 "of %d%%", GCTimeLimit);
2171 }
2172 }
2173 size_policy->set_print_gc_time_limit_would_be_exceeded(false);
2174 }
2175 }
2176
2177 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
2178 HandleMark hm; // Discard invalid handles created during verification
2179 gclog_or_tty->print(" VerifyAfterGC:");
2180 Universe::verify(false);
2181 }
2182
2183 // Re-verify object start arrays
2184 if (VerifyObjectStartArray &&
2185 VerifyAfterGC) {
2186 old_gen->verify_object_start_array();
2187 perm_gen->verify_object_start_array();
2188 }
2189
2190 if (ZapUnusedHeapArea) {
2191 old_gen->object_space()->check_mangled_unused_area_complete();
2192 perm_gen->object_space()->check_mangled_unused_area_complete();
2193 }
2194
2195 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
2196
2197 collection_exit.update();
2198
2199 if (PrintHeapAtGC) {
2200 Universe::print_heap_after_gc();
2201 }
2202 if (PrintGCTaskTimeStamps) {
2203 gclog_or_tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " "
2204 INT64_FORMAT,
2205 marking_start.ticks(), compaction_start.ticks(),
2206 collection_exit.ticks());
2207 gc_task_manager()->print_task_time_stamps();
2208 }
2209 }
2210
2211 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
2212 PSYoungGen* young_gen,
2213 PSOldGen* old_gen) {
2214 MutableSpace* const eden_space = young_gen->eden_space();
2215 assert(!eden_space->is_empty(), "eden must be non-empty");
2216 assert(young_gen->virtual_space()->alignment() ==
2217 old_gen->virtual_space()->alignment(), "alignments do not match");
2218
2219 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
2220 return false;
2221 }
2222
2223 // Both generations must be completely committed.
2224 if (young_gen->virtual_space()->uncommitted_size() != 0) {
2225 return false;
2226 }
2227 if (old_gen->virtual_space()->uncommitted_size() != 0) {
2228 return false;
2229 }
2230
2231 // Figure out how much to take from eden. Include the average amount promoted
2232 // in the total; otherwise the next young gen GC will simply bail out to a
2233 // full GC.
2234 const size_t alignment = old_gen->virtual_space()->alignment();
2235 const size_t eden_used = eden_space->used_in_bytes();
2236 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
2237 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
2238 const size_t eden_capacity = eden_space->capacity_in_bytes();
2239
2240 if (absorb_size >= eden_capacity) {
2241 return false; // Must leave some space in eden.
2242 }
2243
2244 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2245 if (new_young_size < young_gen->min_gen_size()) {
2246 return false; // Respect young gen minimum size.
2247 }
2248
2249 if (TraceAdaptiveGCBoundary && Verbose) {
2250 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
2251 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2252 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2253 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2254 absorb_size / K,
2255 eden_capacity / K, (eden_capacity - absorb_size) / K,
2256 young_gen->from_space()->used_in_bytes() / K,
2257 young_gen->to_space()->used_in_bytes() / K,
2258 young_gen->capacity_in_bytes() / K, new_young_size / K);
2259 }
2260
2261 // Fill the unused part of the old gen.
2262 MutableSpace* const old_space = old_gen->object_space();
2263 HeapWord* const unused_start = old_space->top();
2264 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2265
2266 if (unused_words > 0) {
2267 if (unused_words < CollectedHeap::min_fill_size()) {
2268 return false; // If the old gen cannot be filled, must give up.
2269 }
2270 CollectedHeap::fill_with_objects(unused_start, unused_words);
2271 }
2272
2273 // Take the live data from eden and set both top and end in the old gen to
2274 // eden top. (Need to set end because reset_after_change() mangles the region
2275 // from end to virtual_space->high() in debug builds).
2276 HeapWord* const new_top = eden_space->top();
2277 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2278 absorb_size);
2279 young_gen->reset_after_change();
2280 old_space->set_top(new_top);
2281 old_space->set_end(new_top);
2282 old_gen->reset_after_change();
2283
2284 // Update the object start array for the filler object and the data from eden.
2285 ObjectStartArray* const start_array = old_gen->start_array();
2286 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2287 start_array->allocate_block(p);
2288 }
2289
2290 // Could update the promoted average here, but it is not typically updated at
2291 // full GCs and the value to use is unclear. Something like
2292 //
2293 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2294
2295 size_policy->set_bytes_absorbed_from_eden(absorb_size);
2296 return true;
2297 }
2298
2299 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2300 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2301 "shouldn't return NULL");
2302 return ParallelScavengeHeap::gc_task_manager();
2303 }
2304
2305 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2306 bool maximum_heap_compaction) {
2307 // Recursively traverse all live objects and mark them
2308 EventMark m("1 mark object");
2309 TraceTime tm("marking phase", print_phases(), true, gclog_or_tty);
2310
2311 ParallelScavengeHeap* heap = gc_heap();
2312 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2313 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2314 ParallelTaskTerminator terminator(parallel_gc_threads, qset);
2315
2316 PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
2317 PSParallelCompact::FollowStackClosure follow_stack_closure(cm);
2318
2319 {
2320 TraceTime tm_m("par mark", print_phases(), true, gclog_or_tty);
2321
2322 GCTaskQueue* q = GCTaskQueue::create();
2323
2324 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2325 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2326 // We scan the thread roots in parallel
2327 Threads::create_thread_roots_marking_tasks(q);
2328 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2329 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
2330 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2331 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2332 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2333 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::vm_symbols));
2334
2335 if (parallel_gc_threads > 1) {
2336 for (uint j = 0; j < parallel_gc_threads; j++) {
2337 q->enqueue(new StealMarkingTask(&terminator));
2338 }
2339 }
2340
2341 WaitForBarrierGCTask* fin = WaitForBarrierGCTask::create();
2342 q->enqueue(fin);
2343
2344 gc_task_manager()->add_list(q);
2345
2346 fin->wait_for();
2347
2348 // We have to release the barrier tasks!
2349 WaitForBarrierGCTask::destroy(fin);
2350 }
2351
2352 // Process reference objects found during marking
2353 {
2354 TraceTime tm_r("reference processing", print_phases(), true, gclog_or_tty);
2355 if (ref_processor()->processing_is_mt()) {
2356 RefProcTaskExecutor task_executor;
2357 ref_processor()->process_discovered_references(
2358 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2359 &task_executor);
2360 } else {
2361 ref_processor()->process_discovered_references(
2362 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL);
2363 }
2364 }
2365
2366 TraceTime tm_c("class unloading", print_phases(), true, gclog_or_tty);
2367 // Follow system dictionary roots and unload classes.
2368 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
2369
2370 // Follow code cache roots.
2371 CodeCache::do_unloading(is_alive_closure(), &mark_and_push_closure,
2372 purged_class);
2373 follow_stack(cm); // Flush marking stack.
2374
2375 // Update subklass/sibling/implementor links of live klasses
2376 // revisit_klass_stack is used in follow_weak_klass_links().
2377 follow_weak_klass_links(cm);
2378
2379 // Visit symbol and interned string tables and delete unmarked oops
2380 SymbolTable::unlink(is_alive_closure());
2381 StringTable::unlink(is_alive_closure());
2382
2383 assert(cm->marking_stack()->size() == 0, "stack should be empty by now");
2384 assert(cm->overflow_stack()->is_empty(), "stack should be empty by now");
2385 }
2386
2387 // This should be moved to the shared markSweep code!
2388 class PSAlwaysTrueClosure: public BoolObjectClosure {
2389 public:
2390 void do_object(oop p) { ShouldNotReachHere(); }
2391 bool do_object_b(oop p) { return true; }
2392 };
2393 static PSAlwaysTrueClosure always_true;
2394
2395 void PSParallelCompact::adjust_roots() {
2396 // Adjust the pointers to reflect the new locations
2397 EventMark m("3 adjust roots");
2398 TraceTime tm("adjust roots", print_phases(), true, gclog_or_tty);
2399
2400 // General strong roots.
2401 Universe::oops_do(adjust_root_pointer_closure());
2402 ReferenceProcessor::oops_do(adjust_root_pointer_closure());
2403 JNIHandles::oops_do(adjust_root_pointer_closure()); // Global (strong) JNI handles
2404 Threads::oops_do(adjust_root_pointer_closure());
2405 ObjectSynchronizer::oops_do(adjust_root_pointer_closure());
2406 FlatProfiler::oops_do(adjust_root_pointer_closure());
2407 Management::oops_do(adjust_root_pointer_closure());
2408 JvmtiExport::oops_do(adjust_root_pointer_closure());
2409 // SO_AllClasses
2410 SystemDictionary::oops_do(adjust_root_pointer_closure());
2411 vmSymbols::oops_do(adjust_root_pointer_closure());
2412
2413 // Now adjust pointers in remaining weak roots. (All of which should
2414 // have been cleared if they pointed to non-surviving objects.)
2415 // Global (weak) JNI handles
2416 JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure());
2417
2418 CodeCache::oops_do(adjust_pointer_closure());
2419 SymbolTable::oops_do(adjust_root_pointer_closure());
2420 StringTable::oops_do(adjust_root_pointer_closure());
2421 ref_processor()->weak_oops_do(adjust_root_pointer_closure());
2422 // Roots were visited so references into the young gen in roots
2423 // may have been scanned. Process them also.
2424 // Should the reference processor have a span that excludes
2425 // young gen objects?
2426 PSScavenge::reference_processor()->weak_oops_do(
2427 adjust_root_pointer_closure());
2428 }
2429
2430 void PSParallelCompact::compact_perm(ParCompactionManager* cm) {
2431 EventMark m("4 compact perm");
2432 TraceTime tm("compact perm gen", print_phases(), true, gclog_or_tty);
2433 // trace("4");
2434
2435 gc_heap()->perm_gen()->start_array()->reset();
2436 move_and_update(cm, perm_space_id);
2437 }
2438
2439 void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q,
2440 uint parallel_gc_threads)
2441 {
2442 TraceTime tm("drain task setup", print_phases(), true, gclog_or_tty);
2443
2444 const unsigned int task_count = MAX2(parallel_gc_threads, 1U);
2445 for (unsigned int j = 0; j < task_count; j++) {
2446 q->enqueue(new DrainStacksCompactionTask());
2447 }
2448
2449 // Find all regions that are available (can be filled immediately) and
2450 // distribute them to the thread stacks. The iteration is done in reverse
2451 // order (high to low) so the regions will be removed in ascending order.
2452
2453 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2454
2455 size_t fillable_regions = 0; // A count for diagnostic purposes.
2456 unsigned int which = 0; // The worker thread number.
2457
2458 for (unsigned int id = to_space_id; id > perm_space_id; --id) {
2459 SpaceInfo* const space_info = _space_info + id;
2460 MutableSpace* const space = space_info->space();
2461 HeapWord* const new_top = space_info->new_top();
2462
2463 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2464 const size_t end_region =
2465 sd.addr_to_region_idx(sd.region_align_up(new_top));
2466 assert(end_region > 0, "perm gen cannot be empty");
2467
2468 for (size_t cur = end_region - 1; cur >= beg_region; --cur) {
2469 if (sd.region(cur)->claim_unsafe()) {
2470 ParCompactionManager* cm = ParCompactionManager::manager_array(which);
2471 cm->save_for_processing(cur);
2472
2473 if (TraceParallelOldGCCompactionPhase && Verbose) {
2474 const size_t count_mod_8 = fillable_regions & 7;
2475 if (count_mod_8 == 0) gclog_or_tty->print("fillable: ");
2476 gclog_or_tty->print(" " SIZE_FORMAT_W(7), cur);
2477 if (count_mod_8 == 7) gclog_or_tty->cr();
2478 }
2479
2480 NOT_PRODUCT(++fillable_regions;)
2481
2482 // Assign regions to threads in round-robin fashion.
2483 if (++which == task_count) {
2484 which = 0;
2485 }
2486 }
2487 }
2488 }
2489
2490 if (TraceParallelOldGCCompactionPhase) {
2491 if (Verbose && (fillable_regions & 7) != 0) gclog_or_tty->cr();
2492 gclog_or_tty->print_cr("%u initially fillable regions", fillable_regions);
2493 }
2494 }
2495
2496 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2497
2498 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2499 uint parallel_gc_threads) {
2500 TraceTime tm("dense prefix task setup", print_phases(), true, gclog_or_tty);
2501
2502 ParallelCompactData& sd = PSParallelCompact::summary_data();
2503
2504 // Iterate over all the spaces adding tasks for updating
2505 // regions in the dense prefix. Assume that 1 gc thread
2506 // will work on opening the gaps and the remaining gc threads
2507 // will work on the dense prefix.
2508 unsigned int space_id;
2509 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2510 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2511 const MutableSpace* const space = _space_info[space_id].space();
2512
2513 if (dense_prefix_end == space->bottom()) {
2514 // There is no dense prefix for this space.
2515 continue;
2516 }
2517
2518 // The dense prefix is before this region.
2519 size_t region_index_end_dense_prefix =
2520 sd.addr_to_region_idx(dense_prefix_end);
2521 RegionData* const dense_prefix_cp =
2522 sd.region(region_index_end_dense_prefix);
2523 assert(dense_prefix_end == space->end() ||
2524 dense_prefix_cp->available() ||
2525 dense_prefix_cp->claimed(),
2526 "The region after the dense prefix should always be ready to fill");
2527
2528 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2529
2530 // Is there dense prefix work?
2531 size_t total_dense_prefix_regions =
2532 region_index_end_dense_prefix - region_index_start;
2533 // How many regions of the dense prefix should be given to
2534 // each thread?
2535 if (total_dense_prefix_regions > 0) {
2536 uint tasks_for_dense_prefix = 1;
2537 if (UseParallelDensePrefixUpdate) {
2538 if (total_dense_prefix_regions <=
2539 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2540 // Don't over partition. This assumes that
2541 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2542 // so there are not many regions to process.
2543 tasks_for_dense_prefix = parallel_gc_threads;
2544 } else {
2545 // Over partition
2546 tasks_for_dense_prefix = parallel_gc_threads *
2547 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2548 }
2549 }
2550 size_t regions_per_thread = total_dense_prefix_regions /
2551 tasks_for_dense_prefix;
2552 // Give each thread at least 1 region.
2553 if (regions_per_thread == 0) {
2554 regions_per_thread = 1;
2555 }
2556
2557 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2558 if (region_index_start >= region_index_end_dense_prefix) {
2559 break;
2560 }
2561 // region_index_end is not processed
2562 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2563 region_index_end_dense_prefix);
2564 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2565 region_index_start,
2566 region_index_end));
2567 region_index_start = region_index_end;
2568 }
2569 }
2570 // This gets any part of the dense prefix that did not
2571 // fit evenly.
2572 if (region_index_start < region_index_end_dense_prefix) {
2573 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2574 region_index_start,
2575 region_index_end_dense_prefix));
2576 }
2577 }
2578 }
2579
2580 void PSParallelCompact::enqueue_region_stealing_tasks(
2581 GCTaskQueue* q,
2582 ParallelTaskTerminator* terminator_ptr,
2583 uint parallel_gc_threads) {
2584 TraceTime tm("steal task setup", print_phases(), true, gclog_or_tty);
2585
2586 // Once a thread has drained it's stack, it should try to steal regions from
2587 // other threads.
2588 if (parallel_gc_threads > 1) {
2589 for (uint j = 0; j < parallel_gc_threads; j++) {
2590 q->enqueue(new StealRegionCompactionTask(terminator_ptr));
2591 }
2592 }
2593 }
2594
2595 void PSParallelCompact::compact() {
2596 EventMark m("5 compact");
2597 // trace("5");
2598 TraceTime tm("compaction phase", print_phases(), true, gclog_or_tty);
2599
2600 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
2601 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
2602 PSOldGen* old_gen = heap->old_gen();
2603 old_gen->start_array()->reset();
2604 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2605 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2606 ParallelTaskTerminator terminator(parallel_gc_threads, qset);
2607
2608 GCTaskQueue* q = GCTaskQueue::create();
2609 enqueue_region_draining_tasks(q, parallel_gc_threads);
2610 enqueue_dense_prefix_tasks(q, parallel_gc_threads);
2611 enqueue_region_stealing_tasks(q, &terminator, parallel_gc_threads);
2612
2613 {
2614 TraceTime tm_pc("par compact", print_phases(), true, gclog_or_tty);
2615
2616 WaitForBarrierGCTask* fin = WaitForBarrierGCTask::create();
2617 q->enqueue(fin);
2618
2619 gc_task_manager()->add_list(q);
2620
2621 fin->wait_for();
2622
2623 // We have to release the barrier tasks!
2624 WaitForBarrierGCTask::destroy(fin);
2625
2626 #ifdef ASSERT
2627 // Verify that all regions have been processed before the deferred updates.
2628 // Note that perm_space_id is skipped; this type of verification is not
2629 // valid until the perm gen is compacted by regions.
2630 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2631 verify_complete(SpaceId(id));
2632 }
2633 #endif
2634 }
2635
2636 {
2637 // Update the deferred objects, if any. Any compaction manager can be used.
2638 TraceTime tm_du("deferred updates", print_phases(), true, gclog_or_tty);
2639 ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2640 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2641 update_deferred_objects(cm, SpaceId(id));
2642 }
2643 }
2644 }
2645
2646 #ifdef ASSERT
2647 void PSParallelCompact::verify_complete(SpaceId space_id) {
2648 // All Regions between space bottom() to new_top() should be marked as filled
2649 // and all Regions between new_top() and top() should be available (i.e.,
2650 // should have been emptied).
2651 ParallelCompactData& sd = summary_data();
2652 SpaceInfo si = _space_info[space_id];
2653 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2654 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2655 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2656 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2657 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2658
2659 bool issued_a_warning = false;
2660
2661 size_t cur_region;
2662 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2663 const RegionData* const c = sd.region(cur_region);
2664 if (!c->completed()) {
2665 warning("region " SIZE_FORMAT " not filled: "
2666 "destination_count=" SIZE_FORMAT,
2667 cur_region, c->destination_count());
2668 issued_a_warning = true;
2669 }
2670 }
2671
2672 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2673 const RegionData* const c = sd.region(cur_region);
2674 if (!c->available()) {
2675 warning("region " SIZE_FORMAT " not empty: "
2676 "destination_count=" SIZE_FORMAT,
2677 cur_region, c->destination_count());
2678 issued_a_warning = true;
2679 }
2680 }
2681
2682 if (issued_a_warning) {
2683 print_region_ranges();
2684 }
2685 }
2686 #endif // #ifdef ASSERT
2687
2688 void PSParallelCompact::compact_serial(ParCompactionManager* cm) {
2689 EventMark m("5 compact serial");
2690 TraceTime tm("compact serial", print_phases(), true, gclog_or_tty);
2691
2692 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
2693 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
2694
2695 PSYoungGen* young_gen = heap->young_gen();
2696 PSOldGen* old_gen = heap->old_gen();
2697
2698 old_gen->start_array()->reset();
2699 old_gen->move_and_update(cm);
2700 young_gen->move_and_update(cm);
2701 }
2702
2703
2704 void PSParallelCompact::follow_stack(ParCompactionManager* cm) {
2705 while(!cm->overflow_stack()->is_empty()) {
2706 oop obj = cm->overflow_stack()->pop();
2707 obj->follow_contents(cm);
2708 }
2709
2710 oop obj;
2711 // obj is a reference!!!
2712 while (cm->marking_stack()->pop_local(obj)) {
2713 // It would be nice to assert about the type of objects we might
2714 // pop, but they can come from anywhere, unfortunately.
2715 obj->follow_contents(cm);
2716 }
2717 }
2718
2719 void
2720 PSParallelCompact::follow_weak_klass_links(ParCompactionManager* serial_cm) {
2721 // All klasses on the revisit stack are marked at this point.
2722 // Update and follow all subklass, sibling and implementor links.
2723 for (uint i = 0; i < ParallelGCThreads+1; i++) {
2724 ParCompactionManager* cm = ParCompactionManager::manager_array(i);
2725 KeepAliveClosure keep_alive_closure(cm);
2726 for (int i = 0; i < cm->revisit_klass_stack()->length(); i++) {
2727 cm->revisit_klass_stack()->at(i)->follow_weak_klass_links(
2728 is_alive_closure(),
2729 &keep_alive_closure);
2730 }
2731 follow_stack(cm);
2732 }
2733 }
2734
2735 void
2736 PSParallelCompact::revisit_weak_klass_link(ParCompactionManager* cm, Klass* k) {
2737 cm->revisit_klass_stack()->push(k);
2738 }
2739
2740 #ifdef VALIDATE_MARK_SWEEP
2741
2742 void PSParallelCompact::track_adjusted_pointer(void* p, bool isroot) {
2743 if (!ValidateMarkSweep)
2744 return;
2745
2746 if (!isroot) {
2747 if (_pointer_tracking) {
2748 guarantee(_adjusted_pointers->contains(p), "should have seen this pointer");
2749 _adjusted_pointers->remove(p);
2750 }
2751 } else {
2752 ptrdiff_t index = _root_refs_stack->find(p);
2753 if (index != -1) {
2754 int l = _root_refs_stack->length();
2755 if (l > 0 && l - 1 != index) {
2756 void* last = _root_refs_stack->pop();
2757 assert(last != p, "should be different");
2758 _root_refs_stack->at_put(index, last);
2759 } else {
2760 _root_refs_stack->remove(p);
2761 }
2762 }
2763 }
2764 }
2765
2766
2767 void PSParallelCompact::check_adjust_pointer(void* p) {
2768 _adjusted_pointers->push(p);
2769 }
2770
2771
2772 class AdjusterTracker: public OopClosure {
2773 public:
2774 AdjusterTracker() {};
2775 void do_oop(oop* o) { PSParallelCompact::check_adjust_pointer(o); }
2776 void do_oop(narrowOop* o) { PSParallelCompact::check_adjust_pointer(o); }
2777 };
2778
2779
2780 void PSParallelCompact::track_interior_pointers(oop obj) {
2781 if (ValidateMarkSweep) {
2782 _adjusted_pointers->clear();
2783 _pointer_tracking = true;
2784
2785 AdjusterTracker checker;
2786 obj->oop_iterate(&checker);
2787 }
2788 }
2789
2790
2791 void PSParallelCompact::check_interior_pointers() {
2792 if (ValidateMarkSweep) {
2793 _pointer_tracking = false;
2794 guarantee(_adjusted_pointers->length() == 0, "should have processed the same pointers");
2795 }
2796 }
2797
2798
2799 void PSParallelCompact::reset_live_oop_tracking(bool at_perm) {
2800 if (ValidateMarkSweep) {
2801 guarantee((size_t)_live_oops->length() == _live_oops_index, "should be at end of live oops");
2802 _live_oops_index = at_perm ? _live_oops_index_at_perm : 0;
2803 }
2804 }
2805
2806
2807 void PSParallelCompact::register_live_oop(oop p, size_t size) {
2808 if (ValidateMarkSweep) {
2809 _live_oops->push(p);
2810 _live_oops_size->push(size);
2811 _live_oops_index++;
2812 }
2813 }
2814
2815 void PSParallelCompact::validate_live_oop(oop p, size_t size) {
2816 if (ValidateMarkSweep) {
2817 oop obj = _live_oops->at((int)_live_oops_index);
2818 guarantee(obj == p, "should be the same object");
2819 guarantee(_live_oops_size->at((int)_live_oops_index) == size, "should be the same size");
2820 _live_oops_index++;
2821 }
2822 }
2823
2824 void PSParallelCompact::live_oop_moved_to(HeapWord* q, size_t size,
2825 HeapWord* compaction_top) {
2826 assert(oop(q)->forwardee() == NULL || oop(q)->forwardee() == oop(compaction_top),
2827 "should be moved to forwarded location");
2828 if (ValidateMarkSweep) {
2829 PSParallelCompact::validate_live_oop(oop(q), size);
2830 _live_oops_moved_to->push(oop(compaction_top));
2831 }
2832 if (RecordMarkSweepCompaction) {
2833 _cur_gc_live_oops->push(q);
2834 _cur_gc_live_oops_moved_to->push(compaction_top);
2835 _cur_gc_live_oops_size->push(size);
2836 }
2837 }
2838
2839
2840 void PSParallelCompact::compaction_complete() {
2841 if (RecordMarkSweepCompaction) {
2842 GrowableArray<HeapWord*>* _tmp_live_oops = _cur_gc_live_oops;
2843 GrowableArray<HeapWord*>* _tmp_live_oops_moved_to = _cur_gc_live_oops_moved_to;
2844 GrowableArray<size_t> * _tmp_live_oops_size = _cur_gc_live_oops_size;
2845
2846 _cur_gc_live_oops = _last_gc_live_oops;
2847 _cur_gc_live_oops_moved_to = _last_gc_live_oops_moved_to;
2848 _cur_gc_live_oops_size = _last_gc_live_oops_size;
2849 _last_gc_live_oops = _tmp_live_oops;
2850 _last_gc_live_oops_moved_to = _tmp_live_oops_moved_to;
2851 _last_gc_live_oops_size = _tmp_live_oops_size;
2852 }
2853 }
2854
2855
2856 void PSParallelCompact::print_new_location_of_heap_address(HeapWord* q) {
2857 if (!RecordMarkSweepCompaction) {
2858 tty->print_cr("Requires RecordMarkSweepCompaction to be enabled");
2859 return;
2860 }
2861
2862 if (_last_gc_live_oops == NULL) {
2863 tty->print_cr("No compaction information gathered yet");
2864 return;
2865 }
2866
2867 for (int i = 0; i < _last_gc_live_oops->length(); i++) {
2868 HeapWord* old_oop = _last_gc_live_oops->at(i);
2869 size_t sz = _last_gc_live_oops_size->at(i);
2870 if (old_oop <= q && q < (old_oop + sz)) {
2871 HeapWord* new_oop = _last_gc_live_oops_moved_to->at(i);
2872 size_t offset = (q - old_oop);
2873 tty->print_cr("Address " PTR_FORMAT, q);
2874 tty->print_cr(" Was in oop " PTR_FORMAT ", size %d, at offset %d", old_oop, sz, offset);
2875 tty->print_cr(" Now in oop " PTR_FORMAT ", actual address " PTR_FORMAT, new_oop, new_oop + offset);
2876 return;
2877 }
2878 }
2879
2880 tty->print_cr("Address " PTR_FORMAT " not found in live oop information from last GC", q);
2881 }
2882 #endif //VALIDATE_MARK_SWEEP
2883
2884 // Update interior oops in the ranges of regions [beg_region, end_region).
2885 void
2886 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2887 SpaceId space_id,
2888 size_t beg_region,
2889 size_t end_region) {
2890 ParallelCompactData& sd = summary_data();
2891 ParMarkBitMap* const mbm = mark_bitmap();
2892
2893 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2894 HeapWord* const end_addr = sd.region_to_addr(end_region);
2895 assert(beg_region <= end_region, "bad region range");
2896 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2897
2898 #ifdef ASSERT
2899 // Claim the regions to avoid triggering an assert when they are marked as
2900 // filled.
2901 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2902 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2903 }
2904 #endif // #ifdef ASSERT
2905
2906 if (beg_addr != space(space_id)->bottom()) {
2907 // Find the first live object or block of dead space that *starts* in this
2908 // range of regions. If a partial object crosses onto the region, skip it;
2909 // it will be marked for 'deferred update' when the object head is
2910 // processed. If dead space crosses onto the region, it is also skipped; it
2911 // will be filled when the prior region is processed. If neither of those
2912 // apply, the first word in the region is the start of a live object or dead
2913 // space.
2914 assert(beg_addr > space(space_id)->bottom(), "sanity");
2915 const RegionData* const cp = sd.region(beg_region);
2916 if (cp->partial_obj_size() != 0) {
2917 beg_addr = sd.partial_obj_end(beg_region);
2918 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2919 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2920 }
2921 }
2922
2923 if (beg_addr < end_addr) {
2924 // A live object or block of dead space starts in this range of Regions.
2925 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2926
2927 // Create closures and iterate.
2928 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2929 FillClosure fill_closure(cm, space_id);
2930 ParMarkBitMap::IterationStatus status;
2931 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2932 dense_prefix_end);
2933 if (status == ParMarkBitMap::incomplete) {
2934 update_closure.do_addr(update_closure.source());
2935 }
2936 }
2937
2938 // Mark the regions as filled.
2939 RegionData* const beg_cp = sd.region(beg_region);
2940 RegionData* const end_cp = sd.region(end_region);
2941 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2942 cp->set_completed();
2943 }
2944 }
2945
2946 // Return the SpaceId for the space containing addr. If addr is not in the
2947 // heap, last_space_id is returned. In debug mode it expects the address to be
2948 // in the heap and asserts such.
2949 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2950 assert(Universe::heap()->is_in_reserved(addr), "addr not in the heap");
2951
2952 for (unsigned int id = perm_space_id; id < last_space_id; ++id) {
2953 if (_space_info[id].space()->contains(addr)) {
2954 return SpaceId(id);
2955 }
2956 }
2957
2958 assert(false, "no space contains the addr");
2959 return last_space_id;
2960 }
2961
2962 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2963 SpaceId id) {
2964 assert(id < last_space_id, "bad space id");
2965
2966 ParallelCompactData& sd = summary_data();
2967 const SpaceInfo* const space_info = _space_info + id;
2968 ObjectStartArray* const start_array = space_info->start_array();
2969
2970 const MutableSpace* const space = space_info->space();
2971 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2972 HeapWord* const beg_addr = space_info->dense_prefix();
2973 HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2974
2975 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2976 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2977 const RegionData* cur_region;
2978 for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2979 HeapWord* const addr = cur_region->deferred_obj_addr();
2980 if (addr != NULL) {
2981 if (start_array != NULL) {
2982 start_array->allocate_block(addr);
2983 }
2984 oop(addr)->update_contents(cm);
2985 assert(oop(addr)->is_oop_or_null(), "should be an oop now");
2986 }
2987 }
2988 }
2989
2990 // Skip over count live words starting from beg, and return the address of the
2991 // next live word. Unless marked, the word corresponding to beg is assumed to
2992 // be dead. Callers must either ensure beg does not correspond to the middle of
2993 // an object, or account for those live words in some other way. Callers must
2994 // also ensure that there are enough live words in the range [beg, end) to skip.
2995 HeapWord*
2996 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2997 {
2998 assert(count > 0, "sanity");
2999
3000 ParMarkBitMap* m = mark_bitmap();
3001 idx_t bits_to_skip = m->words_to_bits(count);
3002 idx_t cur_beg = m->addr_to_bit(beg);
3003 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
3004
3005 do {
3006 cur_beg = m->find_obj_beg(cur_beg, search_end);
3007 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
3008 const size_t obj_bits = cur_end - cur_beg + 1;
3009 if (obj_bits > bits_to_skip) {
3010 return m->bit_to_addr(cur_beg + bits_to_skip);
3011 }
3012 bits_to_skip -= obj_bits;
3013 cur_beg = cur_end + 1;
3014 } while (bits_to_skip > 0);
3015
3016 // Skipping the desired number of words landed just past the end of an object.
3017 // Find the start of the next object.
3018 cur_beg = m->find_obj_beg(cur_beg, search_end);
3019 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
3020 return m->bit_to_addr(cur_beg);
3021 }
3022
3023 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
3024 SpaceId src_space_id,
3025 size_t src_region_idx)
3026 {
3027 assert(summary_data().is_region_aligned(dest_addr), "not aligned");
3028
3029 const SplitInfo& split_info = _space_info[src_space_id].split_info();
3030 if (split_info.dest_region_addr() == dest_addr) {
3031 // The partial object ending at the split point contains the first word to
3032 // be copied to dest_addr.
3033 return split_info.first_src_addr();
3034 }
3035
3036 const ParallelCompactData& sd = summary_data();
3037 ParMarkBitMap* const bitmap = mark_bitmap();
3038 const size_t RegionSize = ParallelCompactData::RegionSize;
3039
3040 assert(sd.is_region_aligned(dest_addr), "not aligned");
3041 const RegionData* const src_region_ptr = sd.region(src_region_idx);
3042 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
3043 HeapWord* const src_region_destination = src_region_ptr->destination();
3044
3045 assert(dest_addr >= src_region_destination, "wrong src region");
3046 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
3047
3048 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
3049 HeapWord* const src_region_end = src_region_beg + RegionSize;
3050
3051 HeapWord* addr = src_region_beg;
3052 if (dest_addr == src_region_destination) {
3053 // Return the first live word in the source region.
3054 if (partial_obj_size == 0) {
3055 addr = bitmap->find_obj_beg(addr, src_region_end);
3056 assert(addr < src_region_end, "no objects start in src region");
3057 }
3058 return addr;
3059 }
3060
3061 // Must skip some live data.
3062 size_t words_to_skip = dest_addr - src_region_destination;
3063 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
3064
3065 if (partial_obj_size >= words_to_skip) {
3066 // All the live words to skip are part of the partial object.
3067 addr += words_to_skip;
3068 if (partial_obj_size == words_to_skip) {
3069 // Find the first live word past the partial object.
3070 addr = bitmap->find_obj_beg(addr, src_region_end);
3071 assert(addr < src_region_end, "wrong src region");
3072 }
3073 return addr;
3074 }
3075
3076 // Skip over the partial object (if any).
3077 if (partial_obj_size != 0) {
3078 words_to_skip -= partial_obj_size;
3079 addr += partial_obj_size;
3080 }
3081
3082 // Skip over live words due to objects that start in the region.
3083 addr = skip_live_words(addr, src_region_end, words_to_skip);
3084 assert(addr < src_region_end, "wrong src region");
3085 return addr;
3086 }
3087
3088 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
3089 SpaceId src_space_id,
3090 size_t beg_region,
3091 HeapWord* end_addr)
3092 {
3093 ParallelCompactData& sd = summary_data();
3094
3095 #ifdef ASSERT
3096 MutableSpace* const src_space = _space_info[src_space_id].space();
3097 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
3098 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
3099 "src_space_id does not match beg_addr");
3100 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
3101 "src_space_id does not match end_addr");
3102 #endif // #ifdef ASSERT
3103
3104 RegionData* const beg = sd.region(beg_region);
3105 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
3106
3107 // Regions up to new_top() are enqueued if they become available.
3108 HeapWord* const new_top = _space_info[src_space_id].new_top();
3109 RegionData* const enqueue_end =
3110 sd.addr_to_region_ptr(sd.region_align_up(new_top));
3111
3112 for (RegionData* cur = beg; cur < end; ++cur) {
3113 assert(cur->data_size() > 0, "region must have live data");
3114 cur->decrement_destination_count();
3115 if (cur < enqueue_end && cur->available() && cur->claim()) {
3116 cm->save_for_processing(sd.region(cur));
3117 }
3118 }
3119 }
3120
3121 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
3122 SpaceId& src_space_id,
3123 HeapWord*& src_space_top,
3124 HeapWord* end_addr)
3125 {
3126 typedef ParallelCompactData::RegionData RegionData;
3127
3128 ParallelCompactData& sd = PSParallelCompact::summary_data();
3129 const size_t region_size = ParallelCompactData::RegionSize;
3130
3131 size_t src_region_idx = 0;
3132
3133 // Skip empty regions (if any) up to the top of the space.
3134 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
3135 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
3136 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
3137 const RegionData* const top_region_ptr =
3138 sd.addr_to_region_ptr(top_aligned_up);
3139 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
3140 ++src_region_ptr;
3141 }
3142
3143 if (src_region_ptr < top_region_ptr) {
3144 // The next source region is in the current space. Update src_region_idx
3145 // and the source address to match src_region_ptr.
3146 src_region_idx = sd.region(src_region_ptr);
3147 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
3148 if (src_region_addr > closure.source()) {
3149 closure.set_source(src_region_addr);
3150 }
3151 return src_region_idx;
3152 }
3153
3154 // Switch to a new source space and find the first non-empty region.
3155 unsigned int space_id = src_space_id + 1;
3156 assert(space_id < last_space_id, "not enough spaces");
3157
3158 HeapWord* const destination = closure.destination();
3159
3160 do {
3161 MutableSpace* space = _space_info[space_id].space();
3162 HeapWord* const bottom = space->bottom();
3163 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
3164
3165 // Iterate over the spaces that do not compact into themselves.
3166 if (bottom_cp->destination() != bottom) {
3167 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
3168 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
3169
3170 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
3171 if (src_cp->live_obj_size() > 0) {
3172 // Found it.
3173 assert(src_cp->destination() == destination,
3174 "first live obj in the space must match the destination");
3175 assert(src_cp->partial_obj_size() == 0,
3176 "a space cannot begin with a partial obj");
3177
3178 src_space_id = SpaceId(space_id);
3179 src_space_top = space->top();
3180 const size_t src_region_idx = sd.region(src_cp);
3181 closure.set_source(sd.region_to_addr(src_region_idx));
3182 return src_region_idx;
3183 } else {
3184 assert(src_cp->data_size() == 0, "sanity");
3185 }
3186 }
3187 }
3188 } while (++space_id < last_space_id);
3189
3190 assert(false, "no source region was found");
3191 return 0;
3192 }
3193
3194 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
3195 {
3196 typedef ParMarkBitMap::IterationStatus IterationStatus;
3197 const size_t RegionSize = ParallelCompactData::RegionSize;
3198 ParMarkBitMap* const bitmap = mark_bitmap();
3199 ParallelCompactData& sd = summary_data();
3200 RegionData* const region_ptr = sd.region(region_idx);
3201
3202 // Get the items needed to construct the closure.
3203 HeapWord* dest_addr = sd.region_to_addr(region_idx);
3204 SpaceId dest_space_id = space_id(dest_addr);
3205 ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
3206 HeapWord* new_top = _space_info[dest_space_id].new_top();
3207 assert(dest_addr < new_top, "sanity");
3208 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
3209
3210 // Get the source region and related info.
3211 size_t src_region_idx = region_ptr->source_region();
3212 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
3213 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
3214
3215 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3216 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
3217
3218 // Adjust src_region_idx to prepare for decrementing destination counts (the
3219 // destination count is not decremented when a region is copied to itself).
3220 if (src_region_idx == region_idx) {
3221 src_region_idx += 1;
3222 }
3223
3224 if (bitmap->is_unmarked(closure.source())) {
3225 // The first source word is in the middle of an object; copy the remainder
3226 // of the object or as much as will fit. The fact that pointer updates were
3227 // deferred will be noted when the object header is processed.
3228 HeapWord* const old_src_addr = closure.source();
3229 closure.copy_partial_obj();
3230 if (closure.is_full()) {
3231 decrement_destination_counts(cm, src_space_id, src_region_idx,
3232 closure.source());
3233 region_ptr->set_deferred_obj_addr(NULL);
3234 region_ptr->set_completed();
3235 return;
3236 }
3237
3238 HeapWord* const end_addr = sd.region_align_down(closure.source());
3239 if (sd.region_align_down(old_src_addr) != end_addr) {
3240 // The partial object was copied from more than one source region.
3241 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3242
3243 // Move to the next source region, possibly switching spaces as well. All
3244 // args except end_addr may be modified.
3245 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3246 end_addr);
3247 }
3248 }
3249
3250 do {
3251 HeapWord* const cur_addr = closure.source();
3252 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
3253 src_space_top);
3254 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
3255
3256 if (status == ParMarkBitMap::incomplete) {
3257 // The last obj that starts in the source region does not end in the
3258 // region.
3259 assert(closure.source() < end_addr, "sanity")
3260 HeapWord* const obj_beg = closure.source();
3261 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
3262 src_space_top);
3263 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
3264 if (obj_end < range_end) {
3265 // The end was found; the entire object will fit.
3266 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
3267 assert(status != ParMarkBitMap::would_overflow, "sanity");
3268 } else {
3269 // The end was not found; the object will not fit.
3270 assert(range_end < src_space_top, "obj cannot cross space boundary");
3271 status = ParMarkBitMap::would_overflow;
3272 }
3273 }
3274
3275 if (status == ParMarkBitMap::would_overflow) {
3276 // The last object did not fit. Note that interior oop updates were
3277 // deferred, then copy enough of the object to fill the region.
3278 region_ptr->set_deferred_obj_addr(closure.destination());
3279 status = closure.copy_until_full(); // copies from closure.source()
3280
3281 decrement_destination_counts(cm, src_space_id, src_region_idx,
3282 closure.source());
3283 region_ptr->set_completed();
3284 return;
3285 }
3286
3287 if (status == ParMarkBitMap::full) {
3288 decrement_destination_counts(cm, src_space_id, src_region_idx,
3289 closure.source());
3290 region_ptr->set_deferred_obj_addr(NULL);
3291 region_ptr->set_completed();
3292 return;
3293 }
3294
3295 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3296
3297 // Move to the next source region, possibly switching spaces as well. All
3298 // args except end_addr may be modified.
3299 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3300 end_addr);
3301 } while (true);
3302 }
3303
3304 void
3305 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
3306 const MutableSpace* sp = space(space_id);
3307 if (sp->is_empty()) {
3308 return;
3309 }
3310
3311 ParallelCompactData& sd = PSParallelCompact::summary_data();
3312 ParMarkBitMap* const bitmap = mark_bitmap();
3313 HeapWord* const dp_addr = dense_prefix(space_id);
3314 HeapWord* beg_addr = sp->bottom();
3315 HeapWord* end_addr = sp->top();
3316
3317 #ifdef ASSERT
3318 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
3319 if (cm->should_verify_only()) {
3320 VerifyUpdateClosure verify_update(cm, sp);
3321 bitmap->iterate(&verify_update, beg_addr, end_addr);
3322 return;
3323 }
3324
3325 if (cm->should_reset_only()) {
3326 ResetObjectsClosure reset_objects(cm);
3327 bitmap->iterate(&reset_objects, beg_addr, end_addr);
3328 return;
3329 }
3330 #endif
3331
3332 const size_t beg_region = sd.addr_to_region_idx(beg_addr);
3333 const size_t dp_region = sd.addr_to_region_idx(dp_addr);
3334 if (beg_region < dp_region) {
3335 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
3336 }
3337
3338 // The destination of the first live object that starts in the region is one
3339 // past the end of the partial object entering the region (if any).
3340 HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3341 HeapWord* const new_top = _space_info[space_id].new_top();
3342 assert(new_top >= dest_addr, "bad new_top value");
3343 const size_t words = pointer_delta(new_top, dest_addr);
3344
3345 if (words > 0) {
3346 ObjectStartArray* start_array = _space_info[space_id].start_array();
3347 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3348
3349 ParMarkBitMap::IterationStatus status;
3350 status = bitmap->iterate(&closure, dest_addr, end_addr);
3351 assert(status == ParMarkBitMap::full, "iteration not complete");
3352 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3353 "live objects skipped because closure is full");
3354 }
3355 }
3356
3357 jlong PSParallelCompact::millis_since_last_gc() {
3358 jlong ret_val = os::javaTimeMillis() - _time_of_last_gc;
3359 // XXX See note in genCollectedHeap::millis_since_last_gc().
3360 if (ret_val < 0) {
3361 NOT_PRODUCT(warning("time warp: %d", ret_val);)
3362 return 0;
3363 }
3364 return ret_val;
3365 }
3366
3367 void PSParallelCompact::reset_millis_since_last_gc() {
3368 _time_of_last_gc = os::javaTimeMillis();
3369 }
3370
3371 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3372 {
3373 if (source() != destination()) {
3374 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3375 Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3376 }
3377 update_state(words_remaining());
3378 assert(is_full(), "sanity");
3379 return ParMarkBitMap::full;
3380 }
3381
3382 void MoveAndUpdateClosure::copy_partial_obj()
3383 {
3384 size_t words = words_remaining();
3385
3386 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3387 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3388 if (end_addr < range_end) {
3389 words = bitmap()->obj_size(source(), end_addr);
3390 }
3391
3392 // This test is necessary; if omitted, the pointer updates to a partial object
3393 // that crosses the dense prefix boundary could be overwritten.
3394 if (source() != destination()) {
3395 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3396 Copy::aligned_conjoint_words(source(), destination(), words);
3397 }
3398 update_state(words);
3399 }
3400
3401 ParMarkBitMapClosure::IterationStatus
3402 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3403 assert(destination() != NULL, "sanity");
3404 assert(bitmap()->obj_size(addr) == words, "bad size");
3405
3406 _source = addr;
3407 assert(PSParallelCompact::summary_data().calc_new_pointer(source()) ==
3408 destination(), "wrong destination");
3409
3410 if (words > words_remaining()) {
3411 return ParMarkBitMap::would_overflow;
3412 }
3413
3414 // The start_array must be updated even if the object is not moving.
3415 if (_start_array != NULL) {
3416 _start_array->allocate_block(destination());
3417 }
3418
3419 if (destination() != source()) {
3420 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3421 Copy::aligned_conjoint_words(source(), destination(), words);
3422 }
3423
3424 oop moved_oop = (oop) destination();
3425 moved_oop->update_contents(compaction_manager());
3426 assert(moved_oop->is_oop_or_null(), "Object should be whole at this point");
3427
3428 update_state(words);
3429 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3430 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3431 }
3432
3433 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3434 ParCompactionManager* cm,
3435 PSParallelCompact::SpaceId space_id) :
3436 ParMarkBitMapClosure(mbm, cm),
3437 _space_id(space_id),
3438 _start_array(PSParallelCompact::start_array(space_id))
3439 {
3440 }
3441
3442 // Updates the references in the object to their new values.
3443 ParMarkBitMapClosure::IterationStatus
3444 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3445 do_addr(addr);
3446 return ParMarkBitMap::incomplete;
3447 }
3448
3449 // Verify the new location using the forwarding pointer
3450 // from MarkSweep::mark_sweep_phase2(). Set the mark_word
3451 // to the initial value.
3452 ParMarkBitMapClosure::IterationStatus
3453 PSParallelCompact::VerifyUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3454 // The second arg (words) is not used.
3455 oop obj = (oop) addr;
3456 HeapWord* forwarding_ptr = (HeapWord*) obj->mark()->decode_pointer();
3457 HeapWord* new_pointer = summary_data().calc_new_pointer(obj);
3458 if (forwarding_ptr == NULL) {
3459 // The object is dead or not moving.
3460 assert(bitmap()->is_unmarked(obj) || (new_pointer == (HeapWord*) obj),
3461 "Object liveness is wrong.");
3462 return ParMarkBitMap::incomplete;
3463 }
3464 assert(UseParallelOldGCDensePrefix ||
3465 (HeapMaximumCompactionInterval > 1) ||
3466 (MarkSweepAlwaysCompactCount > 1) ||
3467 (forwarding_ptr == new_pointer),
3468 "Calculation of new location is incorrect");
3469 return ParMarkBitMap::incomplete;
3470 }
3471
3472 // Reset objects modified for debug checking.
3473 ParMarkBitMapClosure::IterationStatus
3474 PSParallelCompact::ResetObjectsClosure::do_addr(HeapWord* addr, size_t words) {
3475 // The second arg (words) is not used.
3476 oop obj = (oop) addr;
3477 obj->init_mark();
3478 return ParMarkBitMap::incomplete;
3479 }
3480
3481 // Prepare for compaction. This method is executed once
3482 // (i.e., by a single thread) before compaction.
3483 // Save the updated location of the intArrayKlassObj for
3484 // filling holes in the dense prefix.
3485 void PSParallelCompact::compact_prologue() {
3486 _updated_int_array_klass_obj = (klassOop)
3487 summary_data().calc_new_pointer(Universe::intArrayKlassObj());
3488 }
3489