1 /*
2 * Copyright 2005-2009 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 #include "incls/_precompiled.incl"
26 #include "incls/_psParallelCompact.cpp.incl"
27
28 #include <math.h>
29
30 // All sizes are in HeapWords.
31 const size_t ParallelCompactData::Log2RegionSize = 9; // 512 words
32 const size_t ParallelCompactData::RegionSize = (size_t)1 << Log2RegionSize;
33 const size_t ParallelCompactData::RegionSizeBytes =
34 RegionSize << LogHeapWordSize;
35 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
36 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
37 const size_t ParallelCompactData::RegionAddrMask = ~RegionAddrOffsetMask;
38
39 const ParallelCompactData::RegionData::region_sz_t
40 ParallelCompactData::RegionData::dc_shift = 27;
41
42 const ParallelCompactData::RegionData::region_sz_t
43 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
44
45 const ParallelCompactData::RegionData::region_sz_t
46 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
47
48 const ParallelCompactData::RegionData::region_sz_t
49 ParallelCompactData::RegionData::los_mask = ~dc_mask;
50
51 const ParallelCompactData::RegionData::region_sz_t
52 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
53
54 const ParallelCompactData::RegionData::region_sz_t
55 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
56
57 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
58 bool PSParallelCompact::_print_phases = false;
59
60 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
61 klassOop PSParallelCompact::_updated_int_array_klass_obj = NULL;
62
63 double PSParallelCompact::_dwl_mean;
64 double PSParallelCompact::_dwl_std_dev;
65 double PSParallelCompact::_dwl_first_term;
66 double PSParallelCompact::_dwl_adjustment;
67 #ifdef ASSERT
68 bool PSParallelCompact::_dwl_initialized = false;
69 #endif // #ifdef ASSERT
70
71 #ifdef VALIDATE_MARK_SWEEP
72 GrowableArray<void*>* PSParallelCompact::_root_refs_stack = NULL;
73 GrowableArray<oop> * PSParallelCompact::_live_oops = NULL;
74 GrowableArray<oop> * PSParallelCompact::_live_oops_moved_to = NULL;
75 GrowableArray<size_t>* PSParallelCompact::_live_oops_size = NULL;
76 size_t PSParallelCompact::_live_oops_index = 0;
77 size_t PSParallelCompact::_live_oops_index_at_perm = 0;
78 GrowableArray<void*>* PSParallelCompact::_other_refs_stack = NULL;
79 GrowableArray<void*>* PSParallelCompact::_adjusted_pointers = NULL;
80 bool PSParallelCompact::_pointer_tracking = false;
81 bool PSParallelCompact::_root_tracking = true;
82
83 GrowableArray<HeapWord*>* PSParallelCompact::_cur_gc_live_oops = NULL;
84 GrowableArray<HeapWord*>* PSParallelCompact::_cur_gc_live_oops_moved_to = NULL;
85 GrowableArray<size_t> * PSParallelCompact::_cur_gc_live_oops_size = NULL;
86 GrowableArray<HeapWord*>* PSParallelCompact::_last_gc_live_oops = NULL;
87 GrowableArray<HeapWord*>* PSParallelCompact::_last_gc_live_oops_moved_to = NULL;
88 GrowableArray<size_t> * PSParallelCompact::_last_gc_live_oops_size = NULL;
89 #endif
90
91 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
92 HeapWord* destination)
93 {
94 assert(src_region_idx != 0, "invalid src_region_idx");
95 assert(partial_obj_size != 0, "invalid partial_obj_size argument");
96 assert(destination != NULL, "invalid destination argument");
97
98 _src_region_idx = src_region_idx;
99 _partial_obj_size = partial_obj_size;
100 _destination = destination;
101
102 // These fields may not be updated below, so make sure they're clear.
103 assert(_dest_region_addr == NULL, "should have been cleared");
104 assert(_first_src_addr == NULL, "should have been cleared");
105
106 // Determine the number of destination regions for the partial object.
107 HeapWord* const last_word = destination + partial_obj_size - 1;
108 const ParallelCompactData& sd = PSParallelCompact::summary_data();
109 HeapWord* const beg_region_addr = sd.region_align_down(destination);
110 HeapWord* const end_region_addr = sd.region_align_down(last_word);
111
112 if (beg_region_addr == end_region_addr) {
113 // One destination region.
114 _destination_count = 1;
115 if (end_region_addr == destination) {
116 // The destination falls on a region boundary, thus the first word of the
117 // partial object will be the first word copied to the destination region.
118 _dest_region_addr = end_region_addr;
119 _first_src_addr = sd.region_to_addr(src_region_idx);
120 }
121 } else {
122 // Two destination regions. When copied, the partial object will cross a
123 // destination region boundary, so a word somewhere within the partial
124 // object will be the first word copied to the second destination region.
125 _destination_count = 2;
126 _dest_region_addr = end_region_addr;
127 const size_t ofs = pointer_delta(end_region_addr, destination);
128 assert(ofs < _partial_obj_size, "sanity");
129 _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
130 }
131 }
132
133 void SplitInfo::clear()
134 {
135 _src_region_idx = 0;
136 _partial_obj_size = 0;
137 _destination = NULL;
138 _destination_count = 0;
139 _dest_region_addr = NULL;
140 _first_src_addr = NULL;
141 assert(!is_valid(), "sanity");
142 }
143
144 #ifdef ASSERT
145 void SplitInfo::verify_clear()
146 {
147 assert(_src_region_idx == 0, "not clear");
148 assert(_partial_obj_size == 0, "not clear");
149 assert(_destination == NULL, "not clear");
150 assert(_destination_count == 0, "not clear");
151 assert(_dest_region_addr == NULL, "not clear");
152 assert(_first_src_addr == NULL, "not clear");
153 }
154 #endif // #ifdef ASSERT
155
156
157 #ifndef PRODUCT
158 const char* PSParallelCompact::space_names[] = {
159 "perm", "old ", "eden", "from", "to "
160 };
161
162 void PSParallelCompact::print_region_ranges()
163 {
164 tty->print_cr("space bottom top end new_top");
165 tty->print_cr("------ ---------- ---------- ---------- ----------");
166
167 for (unsigned int id = 0; id < last_space_id; ++id) {
168 const MutableSpace* space = _space_info[id].space();
169 tty->print_cr("%u %s "
170 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
171 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
172 id, space_names[id],
173 summary_data().addr_to_region_idx(space->bottom()),
174 summary_data().addr_to_region_idx(space->top()),
175 summary_data().addr_to_region_idx(space->end()),
176 summary_data().addr_to_region_idx(_space_info[id].new_top()));
177 }
178 }
179
180 void
181 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
182 {
183 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7)
184 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5)
185
186 ParallelCompactData& sd = PSParallelCompact::summary_data();
187 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
188 tty->print_cr(REGION_IDX_FORMAT " " PTR_FORMAT " "
189 REGION_IDX_FORMAT " " PTR_FORMAT " "
190 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
191 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
192 i, c->data_location(), dci, c->destination(),
193 c->partial_obj_size(), c->live_obj_size(),
194 c->data_size(), c->source_region(), c->destination_count());
195
196 #undef REGION_IDX_FORMAT
197 #undef REGION_DATA_FORMAT
198 }
199
200 void
201 print_generic_summary_data(ParallelCompactData& summary_data,
202 HeapWord* const beg_addr,
203 HeapWord* const end_addr)
204 {
205 size_t total_words = 0;
206 size_t i = summary_data.addr_to_region_idx(beg_addr);
207 const size_t last = summary_data.addr_to_region_idx(end_addr);
208 HeapWord* pdest = 0;
209
210 while (i <= last) {
211 ParallelCompactData::RegionData* c = summary_data.region(i);
212 if (c->data_size() != 0 || c->destination() != pdest) {
213 print_generic_summary_region(i, c);
214 total_words += c->data_size();
215 pdest = c->destination();
216 }
217 ++i;
218 }
219
220 tty->print_cr("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
221 }
222
223 void
224 print_generic_summary_data(ParallelCompactData& summary_data,
225 SpaceInfo* space_info)
226 {
227 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
228 const MutableSpace* space = space_info[id].space();
229 print_generic_summary_data(summary_data, space->bottom(),
230 MAX2(space->top(), space_info[id].new_top()));
231 }
232 }
233
234 void
235 print_initial_summary_region(size_t i,
236 const ParallelCompactData::RegionData* c,
237 bool newline = true)
238 {
239 tty->print(SIZE_FORMAT_W(5) " " PTR_FORMAT " "
240 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " "
241 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
242 i, c->destination(),
243 c->partial_obj_size(), c->live_obj_size(),
244 c->data_size(), c->source_region(), c->destination_count());
245 if (newline) tty->cr();
246 }
247
248 void
249 print_initial_summary_data(ParallelCompactData& summary_data,
250 const MutableSpace* space) {
251 if (space->top() == space->bottom()) {
252 return;
253 }
254
255 const size_t region_size = ParallelCompactData::RegionSize;
256 typedef ParallelCompactData::RegionData RegionData;
257 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
258 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
259 const RegionData* c = summary_data.region(end_region - 1);
260 HeapWord* end_addr = c->destination() + c->data_size();
261 const size_t live_in_space = pointer_delta(end_addr, space->bottom());
262
263 // Print (and count) the full regions at the beginning of the space.
264 size_t full_region_count = 0;
265 size_t i = summary_data.addr_to_region_idx(space->bottom());
266 while (i < end_region && summary_data.region(i)->data_size() == region_size) {
267 print_initial_summary_region(i, summary_data.region(i));
268 ++full_region_count;
269 ++i;
270 }
271
272 size_t live_to_right = live_in_space - full_region_count * region_size;
273
274 double max_reclaimed_ratio = 0.0;
275 size_t max_reclaimed_ratio_region = 0;
276 size_t max_dead_to_right = 0;
277 size_t max_live_to_right = 0;
278
279 // Print the 'reclaimed ratio' for regions while there is something live in
280 // the region or to the right of it. The remaining regions are empty (and
281 // uninteresting), and computing the ratio will result in division by 0.
282 while (i < end_region && live_to_right > 0) {
283 c = summary_data.region(i);
284 HeapWord* const region_addr = summary_data.region_to_addr(i);
285 const size_t used_to_right = pointer_delta(space->top(), region_addr);
286 const size_t dead_to_right = used_to_right - live_to_right;
287 const double reclaimed_ratio = double(dead_to_right) / live_to_right;
288
289 if (reclaimed_ratio > max_reclaimed_ratio) {
290 max_reclaimed_ratio = reclaimed_ratio;
291 max_reclaimed_ratio_region = i;
292 max_dead_to_right = dead_to_right;
293 max_live_to_right = live_to_right;
294 }
295
296 print_initial_summary_region(i, c, false);
297 tty->print_cr(" %12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
298 reclaimed_ratio, dead_to_right, live_to_right);
299
300 live_to_right -= c->data_size();
301 ++i;
302 }
303
304 // Any remaining regions are empty. Print one more if there is one.
305 if (i < end_region) {
306 print_initial_summary_region(i, summary_data.region(i));
307 }
308
309 tty->print_cr("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " "
310 "l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
311 max_reclaimed_ratio_region, max_dead_to_right,
312 max_live_to_right, max_reclaimed_ratio);
313 }
314
315 void
316 print_initial_summary_data(ParallelCompactData& summary_data,
317 SpaceInfo* space_info) {
318 unsigned int id = PSParallelCompact::perm_space_id;
319 const MutableSpace* space;
320 do {
321 space = space_info[id].space();
322 print_initial_summary_data(summary_data, space);
323 } while (++id < PSParallelCompact::eden_space_id);
324
325 do {
326 space = space_info[id].space();
327 print_generic_summary_data(summary_data, space->bottom(), space->top());
328 } while (++id < PSParallelCompact::last_space_id);
329 }
330 #endif // #ifndef PRODUCT
331
332 #ifdef ASSERT
333 size_t add_obj_count;
334 size_t add_obj_size;
335 size_t mark_bitmap_count;
336 size_t mark_bitmap_size;
337 #endif // #ifdef ASSERT
338
339 ParallelCompactData::ParallelCompactData()
340 {
341 _region_start = 0;
342
343 _region_vspace = 0;
344 _region_data = 0;
345 _region_count = 0;
346 }
347
348 bool ParallelCompactData::initialize(MemRegion covered_region)
349 {
350 _region_start = covered_region.start();
351 const size_t region_size = covered_region.word_size();
352 DEBUG_ONLY(_region_end = _region_start + region_size;)
353
354 assert(region_align_down(_region_start) == _region_start,
355 "region start not aligned");
356 assert((region_size & RegionSizeOffsetMask) == 0,
357 "region size not a multiple of RegionSize");
358
359 bool result = initialize_region_data(region_size);
360
361 return result;
362 }
363
364 PSVirtualSpace*
365 ParallelCompactData::create_vspace(size_t count, size_t element_size)
366 {
367 const size_t raw_bytes = count * element_size;
368 const size_t page_sz = os::page_size_for_region(raw_bytes, raw_bytes, 10);
369 const size_t granularity = os::vm_allocation_granularity();
370 const size_t bytes = align_size_up(raw_bytes, MAX2(page_sz, granularity));
371
372 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
373 MAX2(page_sz, granularity);
374 ReservedSpace rs(bytes, rs_align, rs_align > 0);
375 os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(),
376 rs.size());
377 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
378 if (vspace != 0) {
379 if (vspace->expand_by(bytes)) {
380 return vspace;
381 }
382 delete vspace;
383 // Release memory reserved in the space.
384 rs.release();
385 }
386
387 return 0;
388 }
389
390 bool ParallelCompactData::initialize_region_data(size_t region_size)
391 {
392 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
393 _region_vspace = create_vspace(count, sizeof(RegionData));
394 if (_region_vspace != 0) {
395 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
396 _region_count = count;
397 return true;
398 }
399 return false;
400 }
401
402 void ParallelCompactData::clear()
403 {
404 memset(_region_data, 0, _region_vspace->committed_size());
405 }
406
407 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
408 assert(beg_region <= _region_count, "beg_region out of range");
409 assert(end_region <= _region_count, "end_region out of range");
410
411 const size_t region_cnt = end_region - beg_region;
412 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
413 }
414
415 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
416 {
417 const RegionData* cur_cp = region(region_idx);
418 const RegionData* const end_cp = region(region_count() - 1);
419
420 HeapWord* result = region_to_addr(region_idx);
421 if (cur_cp < end_cp) {
422 do {
423 result += cur_cp->partial_obj_size();
424 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
425 }
426 return result;
427 }
428
429 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
430 {
431 const size_t obj_ofs = pointer_delta(addr, _region_start);
432 const size_t beg_region = obj_ofs >> Log2RegionSize;
433 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
434
435 DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
436 DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
437
438 if (beg_region == end_region) {
439 // All in one region.
440 _region_data[beg_region].add_live_obj(len);
441 return;
442 }
443
444 // First region.
445 const size_t beg_ofs = region_offset(addr);
446 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
447
448 klassOop klass = ((oop)addr)->klass();
449 // Middle regions--completely spanned by this object.
450 for (size_t region = beg_region + 1; region < end_region; ++region) {
451 _region_data[region].set_partial_obj_size(RegionSize);
452 _region_data[region].set_partial_obj_addr(addr);
453 }
454
455 // Last region.
456 const size_t end_ofs = region_offset(addr + len - 1);
457 _region_data[end_region].set_partial_obj_size(end_ofs + 1);
458 _region_data[end_region].set_partial_obj_addr(addr);
459 }
460
461 void
462 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
463 {
464 assert(region_offset(beg) == 0, "not RegionSize aligned");
465 assert(region_offset(end) == 0, "not RegionSize aligned");
466
467 size_t cur_region = addr_to_region_idx(beg);
468 const size_t end_region = addr_to_region_idx(end);
469 HeapWord* addr = beg;
470 while (cur_region < end_region) {
471 _region_data[cur_region].set_destination(addr);
472 _region_data[cur_region].set_destination_count(0);
473 _region_data[cur_region].set_source_region(cur_region);
474 _region_data[cur_region].set_data_location(addr);
475
476 // Update live_obj_size so the region appears completely full.
477 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
478 _region_data[cur_region].set_live_obj_size(live_size);
479
480 ++cur_region;
481 addr += RegionSize;
482 }
483 }
484
485 // Find the point at which a space can be split and, if necessary, record the
486 // split point.
487 //
488 // If the current src region (which overflowed the destination space) doesn't
489 // have a partial object, the split point is at the beginning of the current src
490 // region (an "easy" split, no extra bookkeeping required).
491 //
492 // If the current src region has a partial object, the split point is in the
493 // region where that partial object starts (call it the split_region). If
494 // split_region has a partial object, then the split point is just after that
495 // partial object (a "hard" split where we have to record the split data and
496 // zero the partial_obj_size field). With a "hard" split, we know that the
497 // partial_obj ends within split_region because the partial object that caused
498 // the overflow starts in split_region. If split_region doesn't have a partial
499 // obj, then the split is at the beginning of split_region (another "easy"
500 // split).
501 HeapWord*
502 ParallelCompactData::summarize_split_space(size_t src_region,
503 SplitInfo& split_info,
504 HeapWord* destination,
505 HeapWord* target_end,
506 HeapWord** target_next)
507 {
508 assert(destination <= target_end, "sanity");
509 assert(destination + _region_data[src_region].data_size() > target_end,
510 "region should not fit into target space");
511 assert(is_region_aligned(target_end), "sanity");
512
513 size_t split_region = src_region;
514 HeapWord* split_destination = destination;
515 size_t partial_obj_size = _region_data[src_region].partial_obj_size();
516
517 if (destination + partial_obj_size > target_end) {
518 // The split point is just after the partial object (if any) in the
519 // src_region that contains the start of the object that overflowed the
520 // destination space.
521 //
522 // Find the start of the "overflow" object and set split_region to the
523 // region containing it.
524 HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
525 split_region = addr_to_region_idx(overflow_obj);
526
527 // Clear the source_region field of all destination regions whose first word
528 // came from data after the split point (a non-null source_region field
529 // implies a region must be filled).
530 //
531 // An alternative to the simple loop below: clear during post_compact(),
532 // which uses memcpy instead of individual stores, and is easy to
533 // parallelize. (The downside is that it clears the entire RegionData
534 // object as opposed to just one field.)
535 //
536 // post_compact() would have to clear the summary data up to the highest
537 // address that was written during the summary phase, which would be
538 //
539 // max(top, max(new_top, clear_top))
540 //
541 // where clear_top is a new field in SpaceInfo. Would have to set clear_top
542 // to target_end.
543 const RegionData* const sr = region(split_region);
544 const size_t beg_idx =
545 addr_to_region_idx(region_align_up(sr->destination() +
546 sr->partial_obj_size()));
547 const size_t end_idx = addr_to_region_idx(target_end);
548
549 if (TraceParallelOldGCSummaryPhase) {
550 gclog_or_tty->print_cr("split: clearing source_region field in ["
551 SIZE_FORMAT ", " SIZE_FORMAT ")",
552 beg_idx, end_idx);
553 }
554 for (size_t idx = beg_idx; idx < end_idx; ++idx) {
555 _region_data[idx].set_source_region(0);
556 }
557
558 // Set split_destination and partial_obj_size to reflect the split region.
559 split_destination = sr->destination();
560 partial_obj_size = sr->partial_obj_size();
561 }
562
563 // The split is recorded only if a partial object extends onto the region.
564 if (partial_obj_size != 0) {
565 _region_data[split_region].set_partial_obj_size(0);
566 split_info.record(split_region, partial_obj_size, split_destination);
567 }
568
569 // Setup the continuation addresses.
570 *target_next = split_destination + partial_obj_size;
571 HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
572
573 if (TraceParallelOldGCSummaryPhase) {
574 const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
575 gclog_or_tty->print_cr("%s split: src=" PTR_FORMAT " src_c=" SIZE_FORMAT
576 " pos=" SIZE_FORMAT,
577 split_type, source_next, split_region,
578 partial_obj_size);
579 gclog_or_tty->print_cr("%s split: dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT
580 " tn=" PTR_FORMAT,
581 split_type, split_destination,
582 addr_to_region_idx(split_destination),
583 *target_next);
584
585 if (partial_obj_size != 0) {
586 HeapWord* const po_beg = split_info.destination();
587 HeapWord* const po_end = po_beg + split_info.partial_obj_size();
588 gclog_or_tty->print_cr("%s split: "
589 "po_beg=" PTR_FORMAT " " SIZE_FORMAT " "
590 "po_end=" PTR_FORMAT " " SIZE_FORMAT,
591 split_type,
592 po_beg, addr_to_region_idx(po_beg),
593 po_end, addr_to_region_idx(po_end));
594 }
595 }
596
597 return source_next;
598 }
599
600 bool ParallelCompactData::summarize(SplitInfo& split_info,
601 HeapWord* source_beg, HeapWord* source_end,
602 HeapWord** source_next,
603 HeapWord* target_beg, HeapWord* target_end,
604 HeapWord** target_next)
605 {
606 if (TraceParallelOldGCSummaryPhase) {
607 HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
608 tty->print_cr("sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
609 "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
610 source_beg, source_end, source_next_val,
611 target_beg, target_end, *target_next);
612 }
613
614 size_t cur_region = addr_to_region_idx(source_beg);
615 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
616
617 HeapWord *dest_addr = target_beg;
618 while (cur_region < end_region) {
619 // The destination must be set even if the region has no data.
620 _region_data[cur_region].set_destination(dest_addr);
621
622 size_t words = _region_data[cur_region].data_size();
623 if (words > 0) {
624 // If cur_region does not fit entirely into the target space, find a point
625 // at which the source space can be 'split' so that part is copied to the
626 // target space and the rest is copied elsewhere.
627 if (dest_addr + words > target_end) {
628 assert(source_next != NULL, "source_next is NULL when splitting");
629 *source_next = summarize_split_space(cur_region, split_info, dest_addr,
630 target_end, target_next);
631 return false;
632 }
633
634 // Compute the destination_count for cur_region, and if necessary, update
635 // source_region for a destination region. The source_region field is
636 // updated if cur_region is the first (left-most) region to be copied to a
637 // destination region.
638 //
639 // The destination_count calculation is a bit subtle. A region that has
640 // data that compacts into itself does not count itself as a destination.
641 // This maintains the invariant that a zero count means the region is
642 // available and can be claimed and then filled.
643 uint destination_count = 0;
644 if (split_info.is_split(cur_region)) {
645 // The current region has been split: the partial object will be copied
646 // to one destination space and the remaining data will be copied to
647 // another destination space. Adjust the initial destination_count and,
648 // if necessary, set the source_region field if the partial object will
649 // cross a destination region boundary.
650 destination_count = split_info.destination_count();
651 if (destination_count == 2) {
652 size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
653 _region_data[dest_idx].set_source_region(cur_region);
654 }
655 }
656
657 HeapWord* const last_addr = dest_addr + words - 1;
658 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
659 const size_t dest_region_2 = addr_to_region_idx(last_addr);
660
661 // Initially assume that the destination regions will be the same and
662 // adjust the value below if necessary. Under this assumption, if
663 // cur_region == dest_region_2, then cur_region will be compacted
664 // completely into itself.
665 destination_count += cur_region == dest_region_2 ? 0 : 1;
666 if (dest_region_1 != dest_region_2) {
667 // Destination regions differ; adjust destination_count.
668 destination_count += 1;
669 // Data from cur_region will be copied to the start of dest_region_2.
670 _region_data[dest_region_2].set_source_region(cur_region);
671 } else if (region_offset(dest_addr) == 0) {
672 // Data from cur_region will be copied to the start of the destination
673 // region.
674 _region_data[dest_region_1].set_source_region(cur_region);
675 }
676
677 _region_data[cur_region].set_destination_count(destination_count);
678 _region_data[cur_region].set_data_location(region_to_addr(cur_region));
679 dest_addr += words;
680 }
681
682 ++cur_region;
683 }
684
685 *target_next = dest_addr;
686 return true;
687 }
688
689 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) {
690 assert(addr != NULL, "Should detect NULL oop earlier");
691 assert(PSParallelCompact::gc_heap()->is_in(addr), "addr not in heap");
692 #ifdef ASSERT
693 if (PSParallelCompact::mark_bitmap()->is_unmarked(addr)) {
694 gclog_or_tty->print_cr("calc_new_pointer:: addr " PTR_FORMAT, addr);
695 }
696 #endif
697 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "obj not marked");
698
699 // Region covering the object.
700 size_t region_index = addr_to_region_idx(addr);
701 const RegionData* const region_ptr = region(region_index);
702 HeapWord* const region_addr = region_align_down(addr);
703
704 assert(addr < region_addr + RegionSize, "Region does not cover object");
705 assert(addr_to_region_ptr(region_addr) == region_ptr, "sanity check");
706
707 HeapWord* result = region_ptr->destination();
708
709 // If all the data in the region is live, then the new location of the object
710 // can be calculated from the destination of the region plus the offset of the
711 // object in the region.
712 if (region_ptr->data_size() == RegionSize) {
713 result += pointer_delta(addr, region_addr);
714 return result;
715 }
716
717 // The new location of the object is
718 // region destination +
719 // size of the partial object extending onto the region +
720 // sizes of the live objects in the Region that are to the left of addr
721 const size_t partial_obj_size = region_ptr->partial_obj_size();
722 HeapWord* const search_start = region_addr + partial_obj_size;
723
724 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
725 size_t live_to_left = bitmap->live_words_in_range(search_start, oop(addr));
726
727 result += partial_obj_size + live_to_left;
728 DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result);)
729 return result;
730 }
731
732 klassOop ParallelCompactData::calc_new_klass(klassOop old_klass) {
733 klassOop updated_klass;
734 if (PSParallelCompact::should_update_klass(old_klass)) {
735 updated_klass = (klassOop) calc_new_pointer(old_klass);
736 } else {
737 updated_klass = old_klass;
738 }
739
740 return updated_klass;
741 }
742
743 #ifdef ASSERT
744 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
745 {
746 const size_t* const beg = (const size_t*)vspace->committed_low_addr();
747 const size_t* const end = (const size_t*)vspace->committed_high_addr();
748 for (const size_t* p = beg; p < end; ++p) {
749 assert(*p == 0, "not zero");
750 }
751 }
752
753 void ParallelCompactData::verify_clear()
754 {
755 verify_clear(_region_vspace);
756 }
757 #endif // #ifdef ASSERT
758
759 #ifdef NOT_PRODUCT
760 ParallelCompactData::RegionData* debug_region(size_t region_index) {
761 ParallelCompactData& sd = PSParallelCompact::summary_data();
762 return sd.region(region_index);
763 }
764 #endif
765
766 elapsedTimer PSParallelCompact::_accumulated_time;
767 unsigned int PSParallelCompact::_total_invocations = 0;
768 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
769 jlong PSParallelCompact::_time_of_last_gc = 0;
770 CollectorCounters* PSParallelCompact::_counters = NULL;
771 ParMarkBitMap PSParallelCompact::_mark_bitmap;
772 ParallelCompactData PSParallelCompact::_summary_data;
773
774 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
775
776 void PSParallelCompact::IsAliveClosure::do_object(oop p) { ShouldNotReachHere(); }
777 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
778
779 void PSParallelCompact::KeepAliveClosure::do_oop(oop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
780 void PSParallelCompact::KeepAliveClosure::do_oop(narrowOop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
781
782 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_root_pointer_closure(true);
783 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_pointer_closure(false);
784
785 void PSParallelCompact::AdjustPointerClosure::do_oop(oop* p) { adjust_pointer(p, _is_root); }
786 void PSParallelCompact::AdjustPointerClosure::do_oop(narrowOop* p) { adjust_pointer(p, _is_root); }
787
788 void PSParallelCompact::FollowStackClosure::do_void() { follow_stack(_compaction_manager); }
789
790 void PSParallelCompact::MarkAndPushClosure::do_oop(oop* p) { mark_and_push(_compaction_manager, p); }
791 void PSParallelCompact::MarkAndPushClosure::do_oop(narrowOop* p) { mark_and_push(_compaction_manager, p); }
792
793 void PSParallelCompact::post_initialize() {
794 ParallelScavengeHeap* heap = gc_heap();
795 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
796
797 MemRegion mr = heap->reserved_region();
798 _ref_processor = ReferenceProcessor::create_ref_processor(
799 mr, // span
800 true, // atomic_discovery
801 true, // mt_discovery
802 &_is_alive_closure,
803 ParallelGCThreads,
804 ParallelRefProcEnabled);
805 _counters = new CollectorCounters("PSParallelCompact", 1);
806
807 // Initialize static fields in ParCompactionManager.
808 ParCompactionManager::initialize(mark_bitmap());
809 }
810
811 bool PSParallelCompact::initialize() {
812 ParallelScavengeHeap* heap = gc_heap();
813 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
814 MemRegion mr = heap->reserved_region();
815
816 // Was the old gen get allocated successfully?
817 if (!heap->old_gen()->is_allocated()) {
818 return false;
819 }
820
821 initialize_space_info();
822 initialize_dead_wood_limiter();
823
824 if (!_mark_bitmap.initialize(mr)) {
825 vm_shutdown_during_initialization("Unable to allocate bit map for "
826 "parallel garbage collection for the requested heap size.");
827 return false;
828 }
829
830 if (!_summary_data.initialize(mr)) {
831 vm_shutdown_during_initialization("Unable to allocate tables for "
832 "parallel garbage collection for the requested heap size.");
833 return false;
834 }
835
836 return true;
837 }
838
839 void PSParallelCompact::initialize_space_info()
840 {
841 memset(&_space_info, 0, sizeof(_space_info));
842
843 ParallelScavengeHeap* heap = gc_heap();
844 PSYoungGen* young_gen = heap->young_gen();
845 MutableSpace* perm_space = heap->perm_gen()->object_space();
846
847 _space_info[perm_space_id].set_space(perm_space);
848 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
849 _space_info[eden_space_id].set_space(young_gen->eden_space());
850 _space_info[from_space_id].set_space(young_gen->from_space());
851 _space_info[to_space_id].set_space(young_gen->to_space());
852
853 _space_info[perm_space_id].set_start_array(heap->perm_gen()->start_array());
854 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
855
856 _space_info[perm_space_id].set_min_dense_prefix(perm_space->top());
857 if (TraceParallelOldGCDensePrefix) {
858 tty->print_cr("perm min_dense_prefix=" PTR_FORMAT,
859 _space_info[perm_space_id].min_dense_prefix());
860 }
861 }
862
863 void PSParallelCompact::initialize_dead_wood_limiter()
864 {
865 const size_t max = 100;
866 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
867 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
868 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
869 DEBUG_ONLY(_dwl_initialized = true;)
870 _dwl_adjustment = normal_distribution(1.0);
871 }
872
873 // Simple class for storing info about the heap at the start of GC, to be used
874 // after GC for comparison/printing.
875 class PreGCValues {
876 public:
877 PreGCValues() { }
878 PreGCValues(ParallelScavengeHeap* heap) { fill(heap); }
879
880 void fill(ParallelScavengeHeap* heap) {
881 _heap_used = heap->used();
882 _young_gen_used = heap->young_gen()->used_in_bytes();
883 _old_gen_used = heap->old_gen()->used_in_bytes();
884 _perm_gen_used = heap->perm_gen()->used_in_bytes();
885 };
886
887 size_t heap_used() const { return _heap_used; }
888 size_t young_gen_used() const { return _young_gen_used; }
889 size_t old_gen_used() const { return _old_gen_used; }
890 size_t perm_gen_used() const { return _perm_gen_used; }
891
892 private:
893 size_t _heap_used;
894 size_t _young_gen_used;
895 size_t _old_gen_used;
896 size_t _perm_gen_used;
897 };
898
899 void
900 PSParallelCompact::clear_data_covering_space(SpaceId id)
901 {
902 // At this point, top is the value before GC, new_top() is the value that will
903 // be set at the end of GC. The marking bitmap is cleared to top; nothing
904 // should be marked above top. The summary data is cleared to the larger of
905 // top & new_top.
906 MutableSpace* const space = _space_info[id].space();
907 HeapWord* const bot = space->bottom();
908 HeapWord* const top = space->top();
909 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
910
911 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
912 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
913 _mark_bitmap.clear_range(beg_bit, end_bit);
914
915 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
916 const size_t end_region =
917 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
918 _summary_data.clear_range(beg_region, end_region);
919
920 // Clear the data used to 'split' regions.
921 SplitInfo& split_info = _space_info[id].split_info();
922 if (split_info.is_valid()) {
923 split_info.clear();
924 }
925 DEBUG_ONLY(split_info.verify_clear();)
926 }
927
928 void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values)
929 {
930 // Update the from & to space pointers in space_info, since they are swapped
931 // at each young gen gc. Do the update unconditionally (even though a
932 // promotion failure does not swap spaces) because an unknown number of minor
933 // collections will have swapped the spaces an unknown number of times.
934 TraceTime tm("pre compact", print_phases(), true, gclog_or_tty);
935 ParallelScavengeHeap* heap = gc_heap();
936 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
937 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
938
939 pre_gc_values->fill(heap);
940
941 ParCompactionManager::reset();
942 NOT_PRODUCT(_mark_bitmap.reset_counters());
943 DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
944 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
945
946 // Increment the invocation count
947 heap->increment_total_collections(true);
948
949 // We need to track unique mark sweep invocations as well.
950 _total_invocations++;
951
952 if (PrintHeapAtGC) {
953 Universe::print_heap_before_gc();
954 }
955
956 // Fill in TLABs
957 heap->accumulate_statistics_all_tlabs();
958 heap->ensure_parsability(true); // retire TLABs
959
960 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
961 HandleMark hm; // Discard invalid handles created during verification
962 gclog_or_tty->print(" VerifyBeforeGC:");
963 Universe::verify(true);
964 }
965
966 // Verify object start arrays
967 if (VerifyObjectStartArray &&
968 VerifyBeforeGC) {
969 heap->old_gen()->verify_object_start_array();
970 heap->perm_gen()->verify_object_start_array();
971 }
972
973 DEBUG_ONLY(mark_bitmap()->verify_clear();)
974 DEBUG_ONLY(summary_data().verify_clear();)
975
976 // Have worker threads release resources the next time they run a task.
977 gc_task_manager()->release_all_resources();
978 }
979
980 void PSParallelCompact::post_compact()
981 {
982 TraceTime tm("post compact", print_phases(), true, gclog_or_tty);
983
984 for (unsigned int id = perm_space_id; id < last_space_id; ++id) {
985 // Clear the marking bitmap, summary data and split info.
986 clear_data_covering_space(SpaceId(id));
987 // Update top(). Must be done after clearing the bitmap and summary data.
988 _space_info[id].publish_new_top();
989 }
990
991 MutableSpace* const eden_space = _space_info[eden_space_id].space();
992 MutableSpace* const from_space = _space_info[from_space_id].space();
993 MutableSpace* const to_space = _space_info[to_space_id].space();
994
995 ParallelScavengeHeap* heap = gc_heap();
996 bool eden_empty = eden_space->is_empty();
997 if (!eden_empty) {
998 eden_empty = absorb_live_data_from_eden(heap->size_policy(),
999 heap->young_gen(), heap->old_gen());
1000 }
1001
1002 // Update heap occupancy information which is used as input to the soft ref
1003 // clearing policy at the next gc.
1004 Universe::update_heap_info_at_gc();
1005
1006 bool young_gen_empty = eden_empty && from_space->is_empty() &&
1007 to_space->is_empty();
1008
1009 BarrierSet* bs = heap->barrier_set();
1010 if (bs->is_a(BarrierSet::ModRef)) {
1011 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
1012 MemRegion old_mr = heap->old_gen()->reserved();
1013 MemRegion perm_mr = heap->perm_gen()->reserved();
1014 assert(perm_mr.end() <= old_mr.start(), "Generations out of order");
1015
1016 if (young_gen_empty) {
1017 modBS->clear(MemRegion(perm_mr.start(), old_mr.end()));
1018 } else {
1019 modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end()));
1020 }
1021 }
1022
1023 Threads::gc_epilogue();
1024 CodeCache::gc_epilogue();
1025
1026 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1027
1028 ref_processor()->enqueue_discovered_references(NULL);
1029
1030 if (ZapUnusedHeapArea) {
1031 heap->gen_mangle_unused_area();
1032 }
1033
1034 // Update time of last GC
1035 reset_millis_since_last_gc();
1036 }
1037
1038 HeapWord*
1039 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1040 bool maximum_compaction)
1041 {
1042 const size_t region_size = ParallelCompactData::RegionSize;
1043 const ParallelCompactData& sd = summary_data();
1044
1045 const MutableSpace* const space = _space_info[id].space();
1046 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1047 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1048 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1049
1050 // Skip full regions at the beginning of the space--they are necessarily part
1051 // of the dense prefix.
1052 size_t full_count = 0;
1053 const RegionData* cp;
1054 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1055 ++full_count;
1056 }
1057
1058 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1059 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1060 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1061 if (maximum_compaction || cp == end_cp || interval_ended) {
1062 _maximum_compaction_gc_num = total_invocations();
1063 return sd.region_to_addr(cp);
1064 }
1065
1066 HeapWord* const new_top = _space_info[id].new_top();
1067 const size_t space_live = pointer_delta(new_top, space->bottom());
1068 const size_t space_used = space->used_in_words();
1069 const size_t space_capacity = space->capacity_in_words();
1070
1071 const double cur_density = double(space_live) / space_capacity;
1072 const double deadwood_density =
1073 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1074 const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1075
1076 if (TraceParallelOldGCDensePrefix) {
1077 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1078 cur_density, deadwood_density, deadwood_goal);
1079 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1080 "space_cap=" SIZE_FORMAT,
1081 space_live, space_used,
1082 space_capacity);
1083 }
1084
1085 // XXX - Use binary search?
1086 HeapWord* dense_prefix = sd.region_to_addr(cp);
1087 const RegionData* full_cp = cp;
1088 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1089 while (cp < end_cp) {
1090 HeapWord* region_destination = cp->destination();
1091 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1092 if (TraceParallelOldGCDensePrefix && Verbose) {
1093 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1094 "dp=" SIZE_FORMAT_W(8) " " "cdw=" SIZE_FORMAT_W(8),
1095 sd.region(cp), region_destination,
1096 dense_prefix, cur_deadwood);
1097 }
1098
1099 if (cur_deadwood >= deadwood_goal) {
1100 // Found the region that has the correct amount of deadwood to the left.
1101 // This typically occurs after crossing a fairly sparse set of regions, so
1102 // iterate backwards over those sparse regions, looking for the region
1103 // that has the lowest density of live objects 'to the right.'
1104 size_t space_to_left = sd.region(cp) * region_size;
1105 size_t live_to_left = space_to_left - cur_deadwood;
1106 size_t space_to_right = space_capacity - space_to_left;
1107 size_t live_to_right = space_live - live_to_left;
1108 double density_to_right = double(live_to_right) / space_to_right;
1109 while (cp > full_cp) {
1110 --cp;
1111 const size_t prev_region_live_to_right = live_to_right -
1112 cp->data_size();
1113 const size_t prev_region_space_to_right = space_to_right + region_size;
1114 double prev_region_density_to_right =
1115 double(prev_region_live_to_right) / prev_region_space_to_right;
1116 if (density_to_right <= prev_region_density_to_right) {
1117 return dense_prefix;
1118 }
1119 if (TraceParallelOldGCDensePrefix && Verbose) {
1120 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1121 "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1122 prev_region_density_to_right);
1123 }
1124 dense_prefix -= region_size;
1125 live_to_right = prev_region_live_to_right;
1126 space_to_right = prev_region_space_to_right;
1127 density_to_right = prev_region_density_to_right;
1128 }
1129 return dense_prefix;
1130 }
1131
1132 dense_prefix += region_size;
1133 ++cp;
1134 }
1135
1136 return dense_prefix;
1137 }
1138
1139 #ifndef PRODUCT
1140 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1141 const SpaceId id,
1142 const bool maximum_compaction,
1143 HeapWord* const addr)
1144 {
1145 const size_t region_idx = summary_data().addr_to_region_idx(addr);
1146 RegionData* const cp = summary_data().region(region_idx);
1147 const MutableSpace* const space = _space_info[id].space();
1148 HeapWord* const new_top = _space_info[id].new_top();
1149
1150 const size_t space_live = pointer_delta(new_top, space->bottom());
1151 const size_t dead_to_left = pointer_delta(addr, cp->destination());
1152 const size_t space_cap = space->capacity_in_words();
1153 const double dead_to_left_pct = double(dead_to_left) / space_cap;
1154 const size_t live_to_right = new_top - cp->destination();
1155 const size_t dead_to_right = space->top() - addr - live_to_right;
1156
1157 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1158 "spl=" SIZE_FORMAT " "
1159 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1160 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1161 " ratio=%10.8f",
1162 algorithm, addr, region_idx,
1163 space_live,
1164 dead_to_left, dead_to_left_pct,
1165 dead_to_right, live_to_right,
1166 double(dead_to_right) / live_to_right);
1167 }
1168 #endif // #ifndef PRODUCT
1169
1170 // Return a fraction indicating how much of the generation can be treated as
1171 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution
1172 // based on the density of live objects in the generation to determine a limit,
1173 // which is then adjusted so the return value is min_percent when the density is
1174 // 1.
1175 //
1176 // The following table shows some return values for a different values of the
1177 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1178 // min_percent is 1.
1179 //
1180 // fraction allowed as dead wood
1181 // -----------------------------------------------------------------
1182 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1183 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1184 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1185 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1186 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1187 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1188 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1189 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1190 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1191 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1192 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1193 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1194 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1195 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1196 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1197 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1198 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1199 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1200 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1201 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1202 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1203 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1204 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1205
1206 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1207 {
1208 assert(_dwl_initialized, "uninitialized");
1209
1210 // The raw limit is the value of the normal distribution at x = density.
1211 const double raw_limit = normal_distribution(density);
1212
1213 // Adjust the raw limit so it becomes the minimum when the density is 1.
1214 //
1215 // First subtract the adjustment value (which is simply the precomputed value
1216 // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1217 // Then add the minimum value, so the minimum is returned when the density is
1218 // 1. Finally, prevent negative values, which occur when the mean is not 0.5.
1219 const double min = double(min_percent) / 100.0;
1220 const double limit = raw_limit - _dwl_adjustment + min;
1221 return MAX2(limit, 0.0);
1222 }
1223
1224 ParallelCompactData::RegionData*
1225 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1226 const RegionData* end)
1227 {
1228 const size_t region_size = ParallelCompactData::RegionSize;
1229 ParallelCompactData& sd = summary_data();
1230 size_t left = sd.region(beg);
1231 size_t right = end > beg ? sd.region(end) - 1 : left;
1232
1233 // Binary search.
1234 while (left < right) {
1235 // Equivalent to (left + right) / 2, but does not overflow.
1236 const size_t middle = left + (right - left) / 2;
1237 RegionData* const middle_ptr = sd.region(middle);
1238 HeapWord* const dest = middle_ptr->destination();
1239 HeapWord* const addr = sd.region_to_addr(middle);
1240 assert(dest != NULL, "sanity");
1241 assert(dest <= addr, "must move left");
1242
1243 if (middle > left && dest < addr) {
1244 right = middle - 1;
1245 } else if (middle < right && middle_ptr->data_size() == region_size) {
1246 left = middle + 1;
1247 } else {
1248 return middle_ptr;
1249 }
1250 }
1251 return sd.region(left);
1252 }
1253
1254 ParallelCompactData::RegionData*
1255 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1256 const RegionData* end,
1257 size_t dead_words)
1258 {
1259 ParallelCompactData& sd = summary_data();
1260 size_t left = sd.region(beg);
1261 size_t right = end > beg ? sd.region(end) - 1 : left;
1262
1263 // Binary search.
1264 while (left < right) {
1265 // Equivalent to (left + right) / 2, but does not overflow.
1266 const size_t middle = left + (right - left) / 2;
1267 RegionData* const middle_ptr = sd.region(middle);
1268 HeapWord* const dest = middle_ptr->destination();
1269 HeapWord* const addr = sd.region_to_addr(middle);
1270 assert(dest != NULL, "sanity");
1271 assert(dest <= addr, "must move left");
1272
1273 const size_t dead_to_left = pointer_delta(addr, dest);
1274 if (middle > left && dead_to_left > dead_words) {
1275 right = middle - 1;
1276 } else if (middle < right && dead_to_left < dead_words) {
1277 left = middle + 1;
1278 } else {
1279 return middle_ptr;
1280 }
1281 }
1282 return sd.region(left);
1283 }
1284
1285 // The result is valid during the summary phase, after the initial summarization
1286 // of each space into itself, and before final summarization.
1287 inline double
1288 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1289 HeapWord* const bottom,
1290 HeapWord* const top,
1291 HeapWord* const new_top)
1292 {
1293 ParallelCompactData& sd = summary_data();
1294
1295 assert(cp != NULL, "sanity");
1296 assert(bottom != NULL, "sanity");
1297 assert(top != NULL, "sanity");
1298 assert(new_top != NULL, "sanity");
1299 assert(top >= new_top, "summary data problem?");
1300 assert(new_top > bottom, "space is empty; should not be here");
1301 assert(new_top >= cp->destination(), "sanity");
1302 assert(top >= sd.region_to_addr(cp), "sanity");
1303
1304 HeapWord* const destination = cp->destination();
1305 const size_t dense_prefix_live = pointer_delta(destination, bottom);
1306 const size_t compacted_region_live = pointer_delta(new_top, destination);
1307 const size_t compacted_region_used = pointer_delta(top,
1308 sd.region_to_addr(cp));
1309 const size_t reclaimable = compacted_region_used - compacted_region_live;
1310
1311 const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1312 return double(reclaimable) / divisor;
1313 }
1314
1315 // Return the address of the end of the dense prefix, a.k.a. the start of the
1316 // compacted region. The address is always on a region boundary.
1317 //
1318 // Completely full regions at the left are skipped, since no compaction can
1319 // occur in those regions. Then the maximum amount of dead wood to allow is
1320 // computed, based on the density (amount live / capacity) of the generation;
1321 // the region with approximately that amount of dead space to the left is
1322 // identified as the limit region. Regions between the last completely full
1323 // region and the limit region are scanned and the one that has the best
1324 // (maximum) reclaimed_ratio() is selected.
1325 HeapWord*
1326 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1327 bool maximum_compaction)
1328 {
1329 if (ParallelOldGCSplitALot) {
1330 if (_space_info[id].dense_prefix() != _space_info[id].space()->bottom()) {
1331 // The value was chosen to provoke splitting a young gen space; use it.
1332 return _space_info[id].dense_prefix();
1333 }
1334 }
1335
1336 const size_t region_size = ParallelCompactData::RegionSize;
1337 const ParallelCompactData& sd = summary_data();
1338
1339 const MutableSpace* const space = _space_info[id].space();
1340 HeapWord* const top = space->top();
1341 HeapWord* const top_aligned_up = sd.region_align_up(top);
1342 HeapWord* const new_top = _space_info[id].new_top();
1343 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1344 HeapWord* const bottom = space->bottom();
1345 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1346 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1347 const RegionData* const new_top_cp =
1348 sd.addr_to_region_ptr(new_top_aligned_up);
1349
1350 // Skip full regions at the beginning of the space--they are necessarily part
1351 // of the dense prefix.
1352 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1353 assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1354 space->is_empty(), "no dead space allowed to the left");
1355 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1356 "region must have dead space");
1357
1358 // The gc number is saved whenever a maximum compaction is done, and used to
1359 // determine when the maximum compaction interval has expired. This avoids
1360 // successive max compactions for different reasons.
1361 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1362 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1363 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1364 total_invocations() == HeapFirstMaximumCompactionCount;
1365 if (maximum_compaction || full_cp == top_cp || interval_ended) {
1366 _maximum_compaction_gc_num = total_invocations();
1367 return sd.region_to_addr(full_cp);
1368 }
1369
1370 const size_t space_live = pointer_delta(new_top, bottom);
1371 const size_t space_used = space->used_in_words();
1372 const size_t space_capacity = space->capacity_in_words();
1373
1374 const double density = double(space_live) / double(space_capacity);
1375 const size_t min_percent_free =
1376 id == perm_space_id ? PermMarkSweepDeadRatio : MarkSweepDeadRatio;
1377 const double limiter = dead_wood_limiter(density, min_percent_free);
1378 const size_t dead_wood_max = space_used - space_live;
1379 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1380 dead_wood_max);
1381
1382 if (TraceParallelOldGCDensePrefix) {
1383 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1384 "space_cap=" SIZE_FORMAT,
1385 space_live, space_used,
1386 space_capacity);
1387 tty->print_cr("dead_wood_limiter(%6.4f, %d)=%6.4f "
1388 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1389 density, min_percent_free, limiter,
1390 dead_wood_max, dead_wood_limit);
1391 }
1392
1393 // Locate the region with the desired amount of dead space to the left.
1394 const RegionData* const limit_cp =
1395 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1396
1397 // Scan from the first region with dead space to the limit region and find the
1398 // one with the best (largest) reclaimed ratio.
1399 double best_ratio = 0.0;
1400 const RegionData* best_cp = full_cp;
1401 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1402 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1403 if (tmp_ratio > best_ratio) {
1404 best_cp = cp;
1405 best_ratio = tmp_ratio;
1406 }
1407 }
1408
1409 #if 0
1410 // Something to consider: if the region with the best ratio is 'close to' the
1411 // first region w/free space, choose the first region with free space
1412 // ("first-free"). The first-free region is usually near the start of the
1413 // heap, which means we are copying most of the heap already, so copy a bit
1414 // more to get complete compaction.
1415 if (pointer_delta(best_cp, full_cp, sizeof(RegionData)) < 4) {
1416 _maximum_compaction_gc_num = total_invocations();
1417 best_cp = full_cp;
1418 }
1419 #endif // #if 0
1420
1421 return sd.region_to_addr(best_cp);
1422 }
1423
1424 #ifndef PRODUCT
1425 void
1426 PSParallelCompact::fill_with_live_objects(SpaceId id, HeapWord* const start,
1427 size_t words)
1428 {
1429 if (TraceParallelOldGCSummaryPhase) {
1430 tty->print_cr("fill_with_live_objects [" PTR_FORMAT " " PTR_FORMAT ") "
1431 SIZE_FORMAT, start, start + words, words);
1432 }
1433
1434 ObjectStartArray* const start_array = _space_info[id].start_array();
1435 CollectedHeap::fill_with_objects(start, words);
1436 for (HeapWord* p = start; p < start + words; p += oop(p)->size()) {
1437 _mark_bitmap.mark_obj(p, words);
1438 _summary_data.add_obj(p, words);
1439 start_array->allocate_block(p);
1440 }
1441 }
1442
1443 void
1444 PSParallelCompact::summarize_new_objects(SpaceId id, HeapWord* start)
1445 {
1446 ParallelCompactData& sd = summary_data();
1447 MutableSpace* space = _space_info[id].space();
1448
1449 // Find the source and destination start addresses.
1450 HeapWord* const src_addr = sd.region_align_down(start);
1451 HeapWord* dst_addr;
1452 if (src_addr < start) {
1453 dst_addr = sd.addr_to_region_ptr(src_addr)->destination();
1454 } else if (src_addr > space->bottom()) {
1455 // The start (the original top() value) is aligned to a region boundary so
1456 // the associated region does not have a destination. Compute the
1457 // destination from the previous region.
1458 RegionData* const cp = sd.addr_to_region_ptr(src_addr) - 1;
1459 dst_addr = cp->destination() + cp->data_size();
1460 } else {
1461 // Filling the entire space.
1462 dst_addr = space->bottom();
1463 }
1464 assert(dst_addr != NULL, "sanity");
1465
1466 // Update the summary data.
1467 bool result = _summary_data.summarize(_space_info[id].split_info(),
1468 src_addr, space->top(), NULL,
1469 dst_addr, space->end(),
1470 _space_info[id].new_top_addr());
1471 assert(result, "should not fail: bad filler object size");
1472 }
1473
1474 void
1475 PSParallelCompact::provoke_split_fill_survivor(SpaceId id)
1476 {
1477 if (total_invocations() % (ParallelOldGCSplitInterval * 3) != 0) {
1478 return;
1479 }
1480
1481 MutableSpace* const space = _space_info[id].space();
1482 if (space->is_empty()) {
1483 HeapWord* b = space->bottom();
1484 HeapWord* t = b + space->capacity_in_words() / 2;
1485 space->set_top(t);
1486 if (ZapUnusedHeapArea) {
1487 space->set_top_for_allocations();
1488 }
1489
1490 size_t obj_len = 8;
1491 while (b + obj_len <= t) {
1492 CollectedHeap::fill_with_object(b, obj_len);
1493 mark_bitmap()->mark_obj(b, obj_len);
1494 summary_data().add_obj(b, obj_len);
1495 b += obj_len;
1496 obj_len = (obj_len & 0x18) + 8; // 8 16 24 32 8 16 24 32 ...
1497 }
1498 if (b < t) {
1499 // The loop didn't completely fill to t (top); adjust top downward.
1500 space->set_top(b);
1501 if (ZapUnusedHeapArea) {
1502 space->set_top_for_allocations();
1503 }
1504 }
1505
1506 HeapWord** nta = _space_info[id].new_top_addr();
1507 bool result = summary_data().summarize(_space_info[id].split_info(),
1508 space->bottom(), space->top(), NULL,
1509 space->bottom(), space->end(), nta);
1510 assert(result, "space must fit into itself");
1511 }
1512 }
1513
1514 void
1515 PSParallelCompact::provoke_split(bool & max_compaction)
1516 {
1517 if (total_invocations() % ParallelOldGCSplitInterval != 0) {
1518 return;
1519 }
1520
1521 const size_t region_size = ParallelCompactData::RegionSize;
1522 ParallelCompactData& sd = summary_data();
1523
1524 MutableSpace* const eden_space = _space_info[eden_space_id].space();
1525 MutableSpace* const from_space = _space_info[from_space_id].space();
1526 const size_t eden_live = pointer_delta(eden_space->top(),
1527 _space_info[eden_space_id].new_top());
1528 const size_t from_live = pointer_delta(from_space->top(),
1529 _space_info[from_space_id].new_top());
1530
1531 const size_t min_fill_size = CollectedHeap::min_fill_size();
1532 const size_t eden_free = pointer_delta(eden_space->end(), eden_space->top());
1533 const size_t eden_fillable = eden_free >= min_fill_size ? eden_free : 0;
1534 const size_t from_free = pointer_delta(from_space->end(), from_space->top());
1535 const size_t from_fillable = from_free >= min_fill_size ? from_free : 0;
1536
1537 // Choose the space to split; need at least 2 regions live (or fillable).
1538 SpaceId id;
1539 MutableSpace* space;
1540 size_t live_words;
1541 size_t fill_words;
1542 if (eden_live + eden_fillable >= region_size * 2) {
1543 id = eden_space_id;
1544 space = eden_space;
1545 live_words = eden_live;
1546 fill_words = eden_fillable;
1547 } else if (from_live + from_fillable >= region_size * 2) {
1548 id = from_space_id;
1549 space = from_space;
1550 live_words = from_live;
1551 fill_words = from_fillable;
1552 } else {
1553 return; // Give up.
1554 }
1555 assert(fill_words == 0 || fill_words >= min_fill_size, "sanity");
1556
1557 if (live_words < region_size * 2) {
1558 // Fill from top() to end() w/live objects of mixed sizes.
1559 HeapWord* const fill_start = space->top();
1560 live_words += fill_words;
1561
1562 space->set_top(fill_start + fill_words);
1563 if (ZapUnusedHeapArea) {
1564 space->set_top_for_allocations();
1565 }
1566
1567 HeapWord* cur_addr = fill_start;
1568 while (fill_words > 0) {
1569 const size_t r = (size_t)os::random() % (region_size / 2) + min_fill_size;
1570 size_t cur_size = MIN2(align_object_size_(r), fill_words);
1571 if (fill_words - cur_size < min_fill_size) {
1572 cur_size = fill_words; // Avoid leaving a fragment too small to fill.
1573 }
1574
1575 CollectedHeap::fill_with_object(cur_addr, cur_size);
1576 mark_bitmap()->mark_obj(cur_addr, cur_size);
1577 sd.add_obj(cur_addr, cur_size);
1578
1579 cur_addr += cur_size;
1580 fill_words -= cur_size;
1581 }
1582
1583 summarize_new_objects(id, fill_start);
1584 }
1585
1586 max_compaction = false;
1587
1588 // Manipulate the old gen so that it has room for about half of the live data
1589 // in the target young gen space (live_words / 2).
1590 id = old_space_id;
1591 space = _space_info[id].space();
1592 const size_t free_at_end = space->free_in_words();
1593 const size_t free_target = align_object_size(live_words / 2);
1594 const size_t dead = pointer_delta(space->top(), _space_info[id].new_top());
1595
1596 if (free_at_end >= free_target + min_fill_size) {
1597 // Fill space above top() and set the dense prefix so everything survives.
1598 HeapWord* const fill_start = space->top();
1599 const size_t fill_size = free_at_end - free_target;
1600 space->set_top(space->top() + fill_size);
1601 if (ZapUnusedHeapArea) {
1602 space->set_top_for_allocations();
1603 }
1604 fill_with_live_objects(id, fill_start, fill_size);
1605 summarize_new_objects(id, fill_start);
1606 _space_info[id].set_dense_prefix(sd.region_align_down(space->top()));
1607 } else if (dead + free_at_end > free_target) {
1608 // Find a dense prefix that makes the right amount of space available.
1609 HeapWord* cur = sd.region_align_down(space->top());
1610 HeapWord* cur_destination = sd.addr_to_region_ptr(cur)->destination();
1611 size_t dead_to_right = pointer_delta(space->end(), cur_destination);
1612 while (dead_to_right < free_target) {
1613 cur -= region_size;
1614 cur_destination = sd.addr_to_region_ptr(cur)->destination();
1615 dead_to_right = pointer_delta(space->end(), cur_destination);
1616 }
1617 _space_info[id].set_dense_prefix(cur);
1618 }
1619 }
1620 #endif // #ifndef PRODUCT
1621
1622 void PSParallelCompact::summarize_spaces_quick()
1623 {
1624 for (unsigned int i = 0; i < last_space_id; ++i) {
1625 const MutableSpace* space = _space_info[i].space();
1626 HeapWord** nta = _space_info[i].new_top_addr();
1627 bool result = _summary_data.summarize(_space_info[i].split_info(),
1628 space->bottom(), space->top(), NULL,
1629 space->bottom(), space->end(), nta);
1630 assert(result, "space must fit into itself");
1631 _space_info[i].set_dense_prefix(space->bottom());
1632 }
1633
1634 #ifndef PRODUCT
1635 if (ParallelOldGCSplitALot) {
1636 provoke_split_fill_survivor(to_space_id);
1637 }
1638 #endif // #ifndef PRODUCT
1639 }
1640
1641 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1642 {
1643 HeapWord* const dense_prefix_end = dense_prefix(id);
1644 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1645 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1646 if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1647 // Only enough dead space is filled so that any remaining dead space to the
1648 // left is larger than the minimum filler object. (The remainder is filled
1649 // during the copy/update phase.)
1650 //
1651 // The size of the dead space to the right of the boundary is not a
1652 // concern, since compaction will be able to use whatever space is
1653 // available.
1654 //
1655 // Here '||' is the boundary, 'x' represents a don't care bit and a box
1656 // surrounds the space to be filled with an object.
1657 //
1658 // In the 32-bit VM, each bit represents two 32-bit words:
1659 // +---+
1660 // a) beg_bits: ... x x x | 0 | || 0 x x ...
1661 // end_bits: ... x x x | 0 | || 0 x x ...
1662 // +---+
1663 //
1664 // In the 64-bit VM, each bit represents one 64-bit word:
1665 // +------------+
1666 // b) beg_bits: ... x x x | 0 || 0 | x x ...
1667 // end_bits: ... x x 1 | 0 || 0 | x x ...
1668 // +------------+
1669 // +-------+
1670 // c) beg_bits: ... x x | 0 0 | || 0 x x ...
1671 // end_bits: ... x 1 | 0 0 | || 0 x x ...
1672 // +-------+
1673 // +-----------+
1674 // d) beg_bits: ... x | 0 0 0 | || 0 x x ...
1675 // end_bits: ... 1 | 0 0 0 | || 0 x x ...
1676 // +-----------+
1677 // +-------+
1678 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ...
1679 // end_bits: ... 0 0 | 0 0 | || 0 x x ...
1680 // +-------+
1681
1682 // Initially assume case a, c or e will apply.
1683 size_t obj_len = (size_t)oopDesc::header_size();
1684 HeapWord* obj_beg = dense_prefix_end - obj_len;
1685
1686 #ifdef _LP64
1687 if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1688 // Case b above.
1689 obj_beg = dense_prefix_end - 1;
1690 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1691 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1692 // Case d above.
1693 obj_beg = dense_prefix_end - 3;
1694 obj_len = 3;
1695 }
1696 #endif // #ifdef _LP64
1697
1698 CollectedHeap::fill_with_object(obj_beg, obj_len);
1699 _mark_bitmap.mark_obj(obj_beg, obj_len);
1700 _summary_data.add_obj(obj_beg, obj_len);
1701 assert(start_array(id) != NULL, "sanity");
1702 start_array(id)->allocate_block(obj_beg);
1703 }
1704 }
1705
1706 void
1707 PSParallelCompact::clear_source_region(HeapWord* beg_addr, HeapWord* end_addr)
1708 {
1709 RegionData* const beg_ptr = _summary_data.addr_to_region_ptr(beg_addr);
1710 HeapWord* const end_aligned_up = _summary_data.region_align_up(end_addr);
1711 RegionData* const end_ptr = _summary_data.addr_to_region_ptr(end_aligned_up);
1712 for (RegionData* cur = beg_ptr; cur < end_ptr; ++cur) {
1713 cur->set_source_region(0);
1714 }
1715 }
1716
1717 void
1718 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1719 {
1720 assert(id < last_space_id, "id out of range");
1721 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom() ||
1722 ParallelOldGCSplitALot && id == old_space_id,
1723 "should have been reset in summarize_spaces_quick()");
1724
1725 const MutableSpace* space = _space_info[id].space();
1726 if (_space_info[id].new_top() != space->bottom()) {
1727 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1728 _space_info[id].set_dense_prefix(dense_prefix_end);
1729
1730 #ifndef PRODUCT
1731 if (TraceParallelOldGCDensePrefix) {
1732 print_dense_prefix_stats("ratio", id, maximum_compaction,
1733 dense_prefix_end);
1734 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1735 print_dense_prefix_stats("density", id, maximum_compaction, addr);
1736 }
1737 #endif // #ifndef PRODUCT
1738
1739 // Recompute the summary data, taking into account the dense prefix. If
1740 // every last byte will be reclaimed, then the existing summary data which
1741 // compacts everything can be left in place.
1742 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1743 // If dead space crosses the dense prefix boundary, it is (at least
1744 // partially) filled with a dummy object, marked live and added to the
1745 // summary data. This simplifies the copy/update phase and must be done
1746 // before the final locations of objects are determined, to prevent
1747 // leaving a fragment of dead space that is too small to fill.
1748 fill_dense_prefix_end(id);
1749
1750 // Compute the destination of each Region, and thus each object.
1751 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1752 _summary_data.summarize(_space_info[id].split_info(),
1753 dense_prefix_end, space->top(), NULL,
1754 dense_prefix_end, space->end(),
1755 _space_info[id].new_top_addr());
1756 }
1757 }
1758
1759 if (TraceParallelOldGCSummaryPhase) {
1760 const size_t region_size = ParallelCompactData::RegionSize;
1761 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1762 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1763 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1764 HeapWord* const new_top = _space_info[id].new_top();
1765 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1766 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1767 tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1768 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1769 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1770 id, space->capacity_in_words(), dense_prefix_end,
1771 dp_region, dp_words / region_size,
1772 cr_words / region_size, new_top);
1773 }
1774 }
1775
1776 #ifndef PRODUCT
1777 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1778 HeapWord* dst_beg, HeapWord* dst_end,
1779 SpaceId src_space_id,
1780 HeapWord* src_beg, HeapWord* src_end)
1781 {
1782 if (TraceParallelOldGCSummaryPhase) {
1783 tty->print_cr("summarizing %d [%s] into %d [%s]: "
1784 "src=" PTR_FORMAT "-" PTR_FORMAT " "
1785 SIZE_FORMAT "-" SIZE_FORMAT " "
1786 "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1787 SIZE_FORMAT "-" SIZE_FORMAT,
1788 src_space_id, space_names[src_space_id],
1789 dst_space_id, space_names[dst_space_id],
1790 src_beg, src_end,
1791 _summary_data.addr_to_region_idx(src_beg),
1792 _summary_data.addr_to_region_idx(src_end),
1793 dst_beg, dst_end,
1794 _summary_data.addr_to_region_idx(dst_beg),
1795 _summary_data.addr_to_region_idx(dst_end));
1796 }
1797 }
1798 #endif // #ifndef PRODUCT
1799
1800 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1801 bool maximum_compaction)
1802 {
1803 EventMark m("2 summarize");
1804 TraceTime tm("summary phase", print_phases(), true, gclog_or_tty);
1805 // trace("2");
1806
1807 #ifdef ASSERT
1808 if (TraceParallelOldGCMarkingPhase) {
1809 tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1810 "add_obj_bytes=" SIZE_FORMAT,
1811 add_obj_count, add_obj_size * HeapWordSize);
1812 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1813 "mark_bitmap_bytes=" SIZE_FORMAT,
1814 mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1815 }
1816 #endif // #ifdef ASSERT
1817
1818 // Quick summarization of each space into itself, to see how much is live.
1819 summarize_spaces_quick();
1820
1821 if (TraceParallelOldGCSummaryPhase) {
1822 tty->print_cr("summary_phase: after summarizing each space to self");
1823 Universe::print();
1824 NOT_PRODUCT(print_region_ranges());
1825 if (Verbose) {
1826 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1827 }
1828 }
1829
1830 // The amount of live data that will end up in old space (assuming it fits).
1831 size_t old_space_total_live = 0;
1832 assert(perm_space_id < old_space_id, "should not count perm data here");
1833 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1834 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1835 _space_info[id].space()->bottom());
1836 }
1837
1838 MutableSpace* const old_space = _space_info[old_space_id].space();
1839 const size_t old_capacity = old_space->capacity_in_words();
1840 if (old_space_total_live > old_capacity) {
1841 // XXX - should also try to expand
1842 maximum_compaction = true;
1843 }
1844 #ifndef PRODUCT
1845 if (ParallelOldGCSplitALot && old_space_total_live < old_capacity) {
1846 provoke_split(maximum_compaction);
1847 }
1848 #endif // #ifndef PRODUCT
1849
1850 // Permanent and Old generations.
1851 summarize_space(perm_space_id, maximum_compaction);
1852 summarize_space(old_space_id, maximum_compaction);
1853
1854 // Summarize the remaining spaces in the young gen. The initial target space
1855 // is the old gen. If a space does not fit entirely into the target, then the
1856 // remainder is compacted into the space itself and that space becomes the new
1857 // target.
1858 SpaceId dst_space_id = old_space_id;
1859 HeapWord* dst_space_end = old_space->end();
1860 HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1861 for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1862 const MutableSpace* space = _space_info[id].space();
1863 const size_t live = pointer_delta(_space_info[id].new_top(),
1864 space->bottom());
1865 const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1866
1867 NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1868 SpaceId(id), space->bottom(), space->top());)
1869 if (live > 0 && live <= available) {
1870 // All the live data will fit.
1871 bool done = _summary_data.summarize(_space_info[id].split_info(),
1872 space->bottom(), space->top(),
1873 NULL,
1874 *new_top_addr, dst_space_end,
1875 new_top_addr);
1876 assert(done, "space must fit into old gen");
1877
1878 // Reset the new_top value for the space.
1879 _space_info[id].set_new_top(space->bottom());
1880 } else if (live > 0) {
1881 // Attempt to fit part of the source space into the target space.
1882 HeapWord* next_src_addr = NULL;
1883 bool done = _summary_data.summarize(_space_info[id].split_info(),
1884 space->bottom(), space->top(),
1885 &next_src_addr,
1886 *new_top_addr, dst_space_end,
1887 new_top_addr);
1888 assert(!done, "space should not fit into old gen");
1889 assert(next_src_addr != NULL, "sanity");
1890
1891 // The source space becomes the new target, so the remainder is compacted
1892 // within the space itself.
1893 dst_space_id = SpaceId(id);
1894 dst_space_end = space->end();
1895 new_top_addr = _space_info[id].new_top_addr();
1896 NOT_PRODUCT(summary_phase_msg(dst_space_id,
1897 space->bottom(), dst_space_end,
1898 SpaceId(id), next_src_addr, space->top());)
1899 done = _summary_data.summarize(_space_info[id].split_info(),
1900 next_src_addr, space->top(),
1901 NULL,
1902 space->bottom(), dst_space_end,
1903 new_top_addr);
1904 assert(done, "space must fit when compacted into itself");
1905 assert(*new_top_addr <= space->top(), "usage should not grow");
1906 }
1907 }
1908
1909 if (TraceParallelOldGCSummaryPhase) {
1910 tty->print_cr("summary_phase: after final summarization");
1911 Universe::print();
1912 NOT_PRODUCT(print_region_ranges());
1913 if (Verbose) {
1914 NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info));
1915 }
1916 }
1917 }
1918
1919 // This method should contain all heap-specific policy for invoking a full
1920 // collection. invoke_no_policy() will only attempt to compact the heap; it
1921 // will do nothing further. If we need to bail out for policy reasons, scavenge
1922 // before full gc, or any other specialized behavior, it needs to be added here.
1923 //
1924 // Note that this method should only be called from the vm_thread while at a
1925 // safepoint.
1926 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1927 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1928 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1929 "should be in vm thread");
1930 ParallelScavengeHeap* heap = gc_heap();
1931 GCCause::Cause gc_cause = heap->gc_cause();
1932 assert(!heap->is_gc_active(), "not reentrant");
1933
1934 PSAdaptiveSizePolicy* policy = heap->size_policy();
1935
1936 // Before each allocation/collection attempt, find out from the
1937 // policy object if GCs are, on the whole, taking too long. If so,
1938 // bail out without attempting a collection. The exceptions are
1939 // for explicitly requested GC's.
1940 if (!policy->gc_time_limit_exceeded() ||
1941 GCCause::is_user_requested_gc(gc_cause) ||
1942 GCCause::is_serviceability_requested_gc(gc_cause)) {
1943 IsGCActiveMark mark;
1944
1945 if (ScavengeBeforeFullGC) {
1946 PSScavenge::invoke_no_policy();
1947 }
1948
1949 PSParallelCompact::invoke_no_policy(maximum_heap_compaction);
1950 }
1951 }
1952
1953 bool ParallelCompactData::region_contains(size_t region_index, HeapWord* addr) {
1954 size_t addr_region_index = addr_to_region_idx(addr);
1955 return region_index == addr_region_index;
1956 }
1957
1958 // This method contains no policy. You should probably
1959 // be calling invoke() instead.
1960 void PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1961 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1962 assert(ref_processor() != NULL, "Sanity");
1963
1964 if (GC_locker::check_active_before_gc()) {
1965 return;
1966 }
1967
1968 TimeStamp marking_start;
1969 TimeStamp compaction_start;
1970 TimeStamp collection_exit;
1971
1972 ParallelScavengeHeap* heap = gc_heap();
1973 GCCause::Cause gc_cause = heap->gc_cause();
1974 PSYoungGen* young_gen = heap->young_gen();
1975 PSOldGen* old_gen = heap->old_gen();
1976 PSPermGen* perm_gen = heap->perm_gen();
1977 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1978
1979 if (ZapUnusedHeapArea) {
1980 // Save information needed to minimize mangling
1981 heap->record_gen_tops_before_GC();
1982 }
1983
1984 heap->pre_full_gc_dump();
1985
1986 _print_phases = PrintGCDetails && PrintParallelOldGCPhaseTimes;
1987
1988 // Make sure data structures are sane, make the heap parsable, and do other
1989 // miscellaneous bookkeeping.
1990 PreGCValues pre_gc_values;
1991 pre_compact(&pre_gc_values);
1992
1993 // Get the compaction manager reserved for the VM thread.
1994 ParCompactionManager* const vmthread_cm =
1995 ParCompactionManager::manager_array(gc_task_manager()->workers());
1996
1997 // Place after pre_compact() where the number of invocations is incremented.
1998 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
1999
2000 {
2001 ResourceMark rm;
2002 HandleMark hm;
2003
2004 const bool is_system_gc = gc_cause == GCCause::_java_lang_system_gc;
2005
2006 // This is useful for debugging but don't change the output the
2007 // the customer sees.
2008 const char* gc_cause_str = "Full GC";
2009 if (is_system_gc && PrintGCDetails) {
2010 gc_cause_str = "Full GC (System)";
2011 }
2012 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2013 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2014 TraceTime t1(gc_cause_str, PrintGC, !PrintGCDetails, gclog_or_tty);
2015 TraceCollectorStats tcs(counters());
2016 TraceMemoryManagerStats tms(true /* Full GC */);
2017
2018 if (TraceGen1Time) accumulated_time()->start();
2019
2020 // Let the size policy know we're starting
2021 size_policy->major_collection_begin();
2022
2023 // When collecting the permanent generation methodOops may be moving,
2024 // so we either have to flush all bcp data or convert it into bci.
2025 CodeCache::gc_prologue();
2026 Threads::gc_prologue();
2027
2028 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
2029 COMPILER2_PRESENT(DerivedPointerTable::clear());
2030
2031 ref_processor()->enable_discovery();
2032 ref_processor()->setup_policy(maximum_heap_compaction);
2033
2034 bool marked_for_unloading = false;
2035
2036 marking_start.update();
2037 marking_phase(vmthread_cm, maximum_heap_compaction);
2038
2039 #ifndef PRODUCT
2040 if (TraceParallelOldGCMarkingPhase) {
2041 gclog_or_tty->print_cr("marking_phase: cas_tries %d cas_retries %d "
2042 "cas_by_another %d",
2043 mark_bitmap()->cas_tries(), mark_bitmap()->cas_retries(),
2044 mark_bitmap()->cas_by_another());
2045 }
2046 #endif // #ifndef PRODUCT
2047
2048 bool max_on_system_gc = UseMaximumCompactionOnSystemGC && is_system_gc;
2049 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
2050
2051 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
2052 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
2053
2054 // adjust_roots() updates Universe::_intArrayKlassObj which is
2055 // needed by the compaction for filling holes in the dense prefix.
2056 adjust_roots();
2057
2058 compaction_start.update();
2059 // Does the perm gen always have to be done serially because
2060 // klasses are used in the update of an object?
2061 compact_perm(vmthread_cm);
2062
2063 if (UseParallelOldGCCompacting) {
2064 compact();
2065 } else {
2066 compact_serial(vmthread_cm);
2067 }
2068
2069 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
2070 // done before resizing.
2071 post_compact();
2072
2073 // Let the size policy know we're done
2074 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
2075
2076 bool free_ratio_in_effect = false;
2077 if ((UseFreeRatioForParallelGC ||
2078 (UseFreeRatioOnlyInSystemGCForParallelGC &&
2079 gc_cause == GCCause::_java_lang_system_gc))) {
2080 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
2081 free_ratio_in_effect = heap->try_to_shrink_by_free_ratio(true);
2082 }
2083
2084 if (!free_ratio_in_effect && UseAdaptiveSizePolicy) {
2085 if (PrintAdaptiveSizePolicy) {
2086 gclog_or_tty->print("AdaptiveSizeStart: ");
2087 gclog_or_tty->stamp();
2088 gclog_or_tty->print_cr(" collection: %d ",
2089 heap->total_collections());
2090 if (Verbose) {
2091 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d"
2092 " perm_gen_capacity: %d ",
2093 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),
2094 perm_gen->capacity_in_bytes());
2095 }
2096 }
2097
2098 // Don't check if the size_policy is ready here. Let
2099 // the size_policy check that internally.
2100 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
2101 ((gc_cause != GCCause::_java_lang_system_gc) ||
2102 UseAdaptiveSizePolicyWithSystemGC)) {
2103 // Calculate optimal free space amounts
2104 assert(young_gen->max_size() >
2105 young_gen->from_space()->capacity_in_bytes() +
2106 young_gen->to_space()->capacity_in_bytes(),
2107 "Sizes of space in young gen are out-of-bounds");
2108 size_t max_eden_size = young_gen->max_size() -
2109 young_gen->from_space()->capacity_in_bytes() -
2110 young_gen->to_space()->capacity_in_bytes();
2111 size_policy->compute_generation_free_space(
2112 young_gen->used_in_bytes(),
2113 young_gen->eden_space()->used_in_bytes(),
2114 old_gen->used_in_bytes(),
2115 perm_gen->used_in_bytes(),
2116 young_gen->eden_space()->capacity_in_bytes(),
2117 old_gen->max_gen_size(),
2118 max_eden_size,
2119 true /* full gc*/,
2120 gc_cause);
2121
2122 heap->resize_old_gen(
2123 size_policy->calculated_old_free_size_in_bytes());
2124
2125 // Don't resize the young generation at an major collection. A
2126 // desired young generation size may have been calculated but
2127 // resizing the young generation complicates the code because the
2128 // resizing of the old generation may have moved the boundary
2129 // between the young generation and the old generation. Let the
2130 // young generation resizing happen at the minor collections.
2131 }
2132 if (PrintAdaptiveSizePolicy) {
2133 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
2134 heap->total_collections());
2135 }
2136 }
2137
2138 if (UsePerfData) {
2139 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
2140 counters->update_counters();
2141 counters->update_old_capacity(old_gen->capacity_in_bytes());
2142 counters->update_young_capacity(young_gen->capacity_in_bytes());
2143 }
2144
2145 heap->resize_all_tlabs();
2146
2147 // We collected the perm gen, so we'll resize it here.
2148 perm_gen->compute_new_size(pre_gc_values.perm_gen_used());
2149
2150 if (TraceGen1Time) accumulated_time()->stop();
2151
2152 if (PrintGC) {
2153 if (PrintGCDetails) {
2154 // No GC timestamp here. This is after GC so it would be confusing.
2155 young_gen->print_used_change(pre_gc_values.young_gen_used());
2156 old_gen->print_used_change(pre_gc_values.old_gen_used());
2157 heap->print_heap_change(pre_gc_values.heap_used());
2158 // Print perm gen last (print_heap_change() excludes the perm gen).
2159 perm_gen->print_used_change(pre_gc_values.perm_gen_used());
2160 } else {
2161 heap->print_heap_change(pre_gc_values.heap_used());
2162 }
2163 }
2164
2165 // Track memory usage and detect low memory
2166 MemoryService::track_memory_usage();
2167 heap->update_counters();
2168
2169 if (PrintGCDetails) {
2170 if (size_policy->print_gc_time_limit_would_be_exceeded()) {
2171 if (size_policy->gc_time_limit_exceeded()) {
2172 gclog_or_tty->print_cr(" GC time is exceeding GCTimeLimit "
2173 "of %d%%", GCTimeLimit);
2174 } else {
2175 gclog_or_tty->print_cr(" GC time would exceed GCTimeLimit "
2176 "of %d%%", GCTimeLimit);
2177 }
2178 }
2179 size_policy->set_print_gc_time_limit_would_be_exceeded(false);
2180 }
2181 }
2182
2183 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
2184 HandleMark hm; // Discard invalid handles created during verification
2185 gclog_or_tty->print(" VerifyAfterGC:");
2186 Universe::verify(false);
2187 }
2188
2189 // Re-verify object start arrays
2190 if (VerifyObjectStartArray &&
2191 VerifyAfterGC) {
2192 old_gen->verify_object_start_array();
2193 perm_gen->verify_object_start_array();
2194 }
2195
2196 if (ZapUnusedHeapArea) {
2197 old_gen->object_space()->check_mangled_unused_area_complete();
2198 perm_gen->object_space()->check_mangled_unused_area_complete();
2199 }
2200
2201 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
2202
2203 collection_exit.update();
2204
2205 if (PrintHeapAtGC) {
2206 Universe::print_heap_after_gc();
2207 }
2208 if (PrintGCTaskTimeStamps) {
2209 gclog_or_tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " "
2210 INT64_FORMAT,
2211 marking_start.ticks(), compaction_start.ticks(),
2212 collection_exit.ticks());
2213 gc_task_manager()->print_task_time_stamps();
2214 }
2215
2216 heap->post_full_gc_dump();
2217
2218 #ifdef TRACESPINNING
2219 ParallelTaskTerminator::print_termination_counts();
2220 #endif
2221 }
2222
2223 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
2224 PSYoungGen* young_gen,
2225 PSOldGen* old_gen) {
2226 MutableSpace* const eden_space = young_gen->eden_space();
2227 assert(!eden_space->is_empty(), "eden must be non-empty");
2228 assert(young_gen->virtual_space()->alignment() ==
2229 old_gen->virtual_space()->alignment(), "alignments do not match");
2230
2231 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
2232 return false;
2233 }
2234
2235 // Both generations must be completely committed.
2236 if (young_gen->virtual_space()->uncommitted_size() != 0) {
2237 return false;
2238 }
2239 if (old_gen->virtual_space()->uncommitted_size() != 0) {
2240 return false;
2241 }
2242
2243 // Figure out how much to take from eden. Include the average amount promoted
2244 // in the total; otherwise the next young gen GC will simply bail out to a
2245 // full GC.
2246 const size_t alignment = old_gen->virtual_space()->alignment();
2247 const size_t eden_used = eden_space->used_in_bytes();
2248 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
2249 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
2250 const size_t eden_capacity = eden_space->capacity_in_bytes();
2251
2252 if (absorb_size >= eden_capacity) {
2253 return false; // Must leave some space in eden.
2254 }
2255
2256 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2257 if (new_young_size < young_gen->min_gen_size()) {
2258 return false; // Respect young gen minimum size.
2259 }
2260
2261 if (TraceAdaptiveGCBoundary && Verbose) {
2262 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
2263 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2264 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2265 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2266 absorb_size / K,
2267 eden_capacity / K, (eden_capacity - absorb_size) / K,
2268 young_gen->from_space()->used_in_bytes() / K,
2269 young_gen->to_space()->used_in_bytes() / K,
2270 young_gen->capacity_in_bytes() / K, new_young_size / K);
2271 }
2272
2273 // Fill the unused part of the old gen.
2274 MutableSpace* const old_space = old_gen->object_space();
2275 HeapWord* const unused_start = old_space->top();
2276 size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2277
2278 if (unused_words > 0) {
2279 if (unused_words < CollectedHeap::min_fill_size()) {
2280 return false; // If the old gen cannot be filled, must give up.
2281 }
2282 CollectedHeap::fill_with_objects(unused_start, unused_words);
2283 }
2284
2285 // Take the live data from eden and set both top and end in the old gen to
2286 // eden top. (Need to set end because reset_after_change() mangles the region
2287 // from end to virtual_space->high() in debug builds).
2288 HeapWord* const new_top = eden_space->top();
2289 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2290 absorb_size);
2291 young_gen->reset_after_change();
2292 old_space->set_top(new_top);
2293 old_space->set_end(new_top);
2294 old_gen->reset_after_change();
2295
2296 // Update the object start array for the filler object and the data from eden.
2297 ObjectStartArray* const start_array = old_gen->start_array();
2298 for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2299 start_array->allocate_block(p);
2300 }
2301
2302 // Could update the promoted average here, but it is not typically updated at
2303 // full GCs and the value to use is unclear. Something like
2304 //
2305 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2306
2307 size_policy->set_bytes_absorbed_from_eden(absorb_size);
2308 return true;
2309 }
2310
2311 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2312 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2313 "shouldn't return NULL");
2314 return ParallelScavengeHeap::gc_task_manager();
2315 }
2316
2317 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2318 bool maximum_heap_compaction) {
2319 // Recursively traverse all live objects and mark them
2320 EventMark m("1 mark object");
2321 TraceTime tm("marking phase", print_phases(), true, gclog_or_tty);
2322
2323 ParallelScavengeHeap* heap = gc_heap();
2324 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2325 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2326 ParallelTaskTerminator terminator(parallel_gc_threads, qset);
2327
2328 PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
2329 PSParallelCompact::FollowStackClosure follow_stack_closure(cm);
2330
2331 {
2332 TraceTime tm_m("par mark", print_phases(), true, gclog_or_tty);
2333 ParallelScavengeHeap::ParStrongRootsScope psrs;
2334
2335 GCTaskQueue* q = GCTaskQueue::create();
2336
2337 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2338 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2339 // We scan the thread roots in parallel
2340 Threads::create_thread_roots_marking_tasks(q);
2341 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2342 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
2343 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2344 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2345 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2346 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::vm_symbols));
2347 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2348
2349 if (parallel_gc_threads > 1) {
2350 for (uint j = 0; j < parallel_gc_threads; j++) {
2351 q->enqueue(new StealMarkingTask(&terminator));
2352 }
2353 }
2354
2355 WaitForBarrierGCTask* fin = WaitForBarrierGCTask::create();
2356 q->enqueue(fin);
2357
2358 gc_task_manager()->add_list(q);
2359
2360 fin->wait_for();
2361
2362 // We have to release the barrier tasks!
2363 WaitForBarrierGCTask::destroy(fin);
2364 }
2365
2366 // Process reference objects found during marking
2367 {
2368 TraceTime tm_r("reference processing", print_phases(), true, gclog_or_tty);
2369 if (ref_processor()->processing_is_mt()) {
2370 RefProcTaskExecutor task_executor;
2371 ref_processor()->process_discovered_references(
2372 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2373 &task_executor);
2374 } else {
2375 ref_processor()->process_discovered_references(
2376 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL);
2377 }
2378 }
2379
2380 TraceTime tm_c("class unloading", print_phases(), true, gclog_or_tty);
2381 // Follow system dictionary roots and unload classes.
2382 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
2383
2384 // Follow code cache roots.
2385 CodeCache::do_unloading(is_alive_closure(), &mark_and_push_closure,
2386 purged_class);
2387 follow_stack(cm); // Flush marking stack.
2388
2389 // Update subklass/sibling/implementor links of live klasses
2390 // revisit_klass_stack is used in follow_weak_klass_links().
2391 follow_weak_klass_links();
2392
2393 // Revisit memoized MDO's and clear any unmarked weak refs
2394 follow_mdo_weak_refs();
2395
2396 // Visit symbol and interned string tables and delete unmarked oops
2397 SymbolTable::unlink(is_alive_closure());
2398 StringTable::unlink(is_alive_closure());
2399
2400 assert(cm->marking_stack()->size() == 0, "stack should be empty by now");
2401 assert(cm->overflow_stack()->is_empty(), "stack should be empty by now");
2402 }
2403
2404 // This should be moved to the shared markSweep code!
2405 class PSAlwaysTrueClosure: public BoolObjectClosure {
2406 public:
2407 void do_object(oop p) { ShouldNotReachHere(); }
2408 bool do_object_b(oop p) { return true; }
2409 };
2410 static PSAlwaysTrueClosure always_true;
2411
2412 void PSParallelCompact::adjust_roots() {
2413 // Adjust the pointers to reflect the new locations
2414 EventMark m("3 adjust roots");
2415 TraceTime tm("adjust roots", print_phases(), true, gclog_or_tty);
2416
2417 // General strong roots.
2418 Universe::oops_do(adjust_root_pointer_closure());
2419 ReferenceProcessor::oops_do(adjust_root_pointer_closure());
2420 JNIHandles::oops_do(adjust_root_pointer_closure()); // Global (strong) JNI handles
2421 Threads::oops_do(adjust_root_pointer_closure(), NULL);
2422 ObjectSynchronizer::oops_do(adjust_root_pointer_closure());
2423 FlatProfiler::oops_do(adjust_root_pointer_closure());
2424 Management::oops_do(adjust_root_pointer_closure());
2425 JvmtiExport::oops_do(adjust_root_pointer_closure());
2426 // SO_AllClasses
2427 SystemDictionary::oops_do(adjust_root_pointer_closure());
2428 vmSymbols::oops_do(adjust_root_pointer_closure());
2429
2430 // Now adjust pointers in remaining weak roots. (All of which should
2431 // have been cleared if they pointed to non-surviving objects.)
2432 // Global (weak) JNI handles
2433 JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure());
2434
2435 CodeCache::oops_do(adjust_pointer_closure());
2436 SymbolTable::oops_do(adjust_root_pointer_closure());
2437 StringTable::oops_do(adjust_root_pointer_closure());
2438 ref_processor()->weak_oops_do(adjust_root_pointer_closure());
2439 // Roots were visited so references into the young gen in roots
2440 // may have been scanned. Process them also.
2441 // Should the reference processor have a span that excludes
2442 // young gen objects?
2443 PSScavenge::reference_processor()->weak_oops_do(
2444 adjust_root_pointer_closure());
2445 }
2446
2447 void PSParallelCompact::compact_perm(ParCompactionManager* cm) {
2448 EventMark m("4 compact perm");
2449 TraceTime tm("compact perm gen", print_phases(), true, gclog_or_tty);
2450 // trace("4");
2451
2452 gc_heap()->perm_gen()->start_array()->reset();
2453 move_and_update(cm, perm_space_id);
2454 }
2455
2456 void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q,
2457 uint parallel_gc_threads)
2458 {
2459 TraceTime tm("drain task setup", print_phases(), true, gclog_or_tty);
2460
2461 const unsigned int task_count = MAX2(parallel_gc_threads, 1U);
2462 for (unsigned int j = 0; j < task_count; j++) {
2463 q->enqueue(new DrainStacksCompactionTask());
2464 }
2465
2466 // Find all regions that are available (can be filled immediately) and
2467 // distribute them to the thread stacks. The iteration is done in reverse
2468 // order (high to low) so the regions will be removed in ascending order.
2469
2470 const ParallelCompactData& sd = PSParallelCompact::summary_data();
2471
2472 size_t fillable_regions = 0; // A count for diagnostic purposes.
2473 unsigned int which = 0; // The worker thread number.
2474
2475 for (unsigned int id = to_space_id; id > perm_space_id; --id) {
2476 SpaceInfo* const space_info = _space_info + id;
2477 MutableSpace* const space = space_info->space();
2478 HeapWord* const new_top = space_info->new_top();
2479
2480 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2481 const size_t end_region =
2482 sd.addr_to_region_idx(sd.region_align_up(new_top));
2483 assert(end_region > 0, "perm gen cannot be empty");
2484
2485 for (size_t cur = end_region - 1; cur >= beg_region; --cur) {
2486 if (sd.region(cur)->claim_unsafe()) {
2487 ParCompactionManager* cm = ParCompactionManager::manager_array(which);
2488 cm->save_for_processing(cur);
2489
2490 if (TraceParallelOldGCCompactionPhase && Verbose) {
2491 const size_t count_mod_8 = fillable_regions & 7;
2492 if (count_mod_8 == 0) gclog_or_tty->print("fillable: ");
2493 gclog_or_tty->print(" " SIZE_FORMAT_W(7), cur);
2494 if (count_mod_8 == 7) gclog_or_tty->cr();
2495 }
2496
2497 NOT_PRODUCT(++fillable_regions;)
2498
2499 // Assign regions to threads in round-robin fashion.
2500 if (++which == task_count) {
2501 which = 0;
2502 }
2503 }
2504 }
2505 }
2506
2507 if (TraceParallelOldGCCompactionPhase) {
2508 if (Verbose && (fillable_regions & 7) != 0) gclog_or_tty->cr();
2509 gclog_or_tty->print_cr("%u initially fillable regions", fillable_regions);
2510 }
2511 }
2512
2513 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2514
2515 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2516 uint parallel_gc_threads) {
2517 TraceTime tm("dense prefix task setup", print_phases(), true, gclog_or_tty);
2518
2519 ParallelCompactData& sd = PSParallelCompact::summary_data();
2520
2521 // Iterate over all the spaces adding tasks for updating
2522 // regions in the dense prefix. Assume that 1 gc thread
2523 // will work on opening the gaps and the remaining gc threads
2524 // will work on the dense prefix.
2525 unsigned int space_id;
2526 for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2527 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2528 const MutableSpace* const space = _space_info[space_id].space();
2529
2530 if (dense_prefix_end == space->bottom()) {
2531 // There is no dense prefix for this space.
2532 continue;
2533 }
2534
2535 // The dense prefix is before this region.
2536 size_t region_index_end_dense_prefix =
2537 sd.addr_to_region_idx(dense_prefix_end);
2538 RegionData* const dense_prefix_cp =
2539 sd.region(region_index_end_dense_prefix);
2540 assert(dense_prefix_end == space->end() ||
2541 dense_prefix_cp->available() ||
2542 dense_prefix_cp->claimed(),
2543 "The region after the dense prefix should always be ready to fill");
2544
2545 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2546
2547 // Is there dense prefix work?
2548 size_t total_dense_prefix_regions =
2549 region_index_end_dense_prefix - region_index_start;
2550 // How many regions of the dense prefix should be given to
2551 // each thread?
2552 if (total_dense_prefix_regions > 0) {
2553 uint tasks_for_dense_prefix = 1;
2554 if (UseParallelDensePrefixUpdate) {
2555 if (total_dense_prefix_regions <=
2556 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2557 // Don't over partition. This assumes that
2558 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2559 // so there are not many regions to process.
2560 tasks_for_dense_prefix = parallel_gc_threads;
2561 } else {
2562 // Over partition
2563 tasks_for_dense_prefix = parallel_gc_threads *
2564 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2565 }
2566 }
2567 size_t regions_per_thread = total_dense_prefix_regions /
2568 tasks_for_dense_prefix;
2569 // Give each thread at least 1 region.
2570 if (regions_per_thread == 0) {
2571 regions_per_thread = 1;
2572 }
2573
2574 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2575 if (region_index_start >= region_index_end_dense_prefix) {
2576 break;
2577 }
2578 // region_index_end is not processed
2579 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2580 region_index_end_dense_prefix);
2581 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2582 region_index_start,
2583 region_index_end));
2584 region_index_start = region_index_end;
2585 }
2586 }
2587 // This gets any part of the dense prefix that did not
2588 // fit evenly.
2589 if (region_index_start < region_index_end_dense_prefix) {
2590 q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2591 region_index_start,
2592 region_index_end_dense_prefix));
2593 }
2594 }
2595 }
2596
2597 void PSParallelCompact::enqueue_region_stealing_tasks(
2598 GCTaskQueue* q,
2599 ParallelTaskTerminator* terminator_ptr,
2600 uint parallel_gc_threads) {
2601 TraceTime tm("steal task setup", print_phases(), true, gclog_or_tty);
2602
2603 // Once a thread has drained it's stack, it should try to steal regions from
2604 // other threads.
2605 if (parallel_gc_threads > 1) {
2606 for (uint j = 0; j < parallel_gc_threads; j++) {
2607 q->enqueue(new StealRegionCompactionTask(terminator_ptr));
2608 }
2609 }
2610 }
2611
2612 void PSParallelCompact::compact() {
2613 EventMark m("5 compact");
2614 // trace("5");
2615 TraceTime tm("compaction phase", print_phases(), true, gclog_or_tty);
2616
2617 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
2618 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
2619 PSOldGen* old_gen = heap->old_gen();
2620 old_gen->start_array()->reset();
2621 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2622 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2623 ParallelTaskTerminator terminator(parallel_gc_threads, qset);
2624
2625 GCTaskQueue* q = GCTaskQueue::create();
2626 enqueue_region_draining_tasks(q, parallel_gc_threads);
2627 enqueue_dense_prefix_tasks(q, parallel_gc_threads);
2628 enqueue_region_stealing_tasks(q, &terminator, parallel_gc_threads);
2629
2630 {
2631 TraceTime tm_pc("par compact", print_phases(), true, gclog_or_tty);
2632
2633 WaitForBarrierGCTask* fin = WaitForBarrierGCTask::create();
2634 q->enqueue(fin);
2635
2636 gc_task_manager()->add_list(q);
2637
2638 fin->wait_for();
2639
2640 // We have to release the barrier tasks!
2641 WaitForBarrierGCTask::destroy(fin);
2642
2643 #ifdef ASSERT
2644 // Verify that all regions have been processed before the deferred updates.
2645 // Note that perm_space_id is skipped; this type of verification is not
2646 // valid until the perm gen is compacted by regions.
2647 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2648 verify_complete(SpaceId(id));
2649 }
2650 #endif
2651 }
2652
2653 {
2654 // Update the deferred objects, if any. Any compaction manager can be used.
2655 TraceTime tm_du("deferred updates", print_phases(), true, gclog_or_tty);
2656 ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2657 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2658 update_deferred_objects(cm, SpaceId(id));
2659 }
2660 }
2661 }
2662
2663 #ifdef ASSERT
2664 void PSParallelCompact::verify_complete(SpaceId space_id) {
2665 // All Regions between space bottom() to new_top() should be marked as filled
2666 // and all Regions between new_top() and top() should be available (i.e.,
2667 // should have been emptied).
2668 ParallelCompactData& sd = summary_data();
2669 SpaceInfo si = _space_info[space_id];
2670 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2671 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2672 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2673 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2674 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2675
2676 bool issued_a_warning = false;
2677
2678 size_t cur_region;
2679 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2680 const RegionData* const c = sd.region(cur_region);
2681 if (!c->completed()) {
2682 warning("region " SIZE_FORMAT " not filled: "
2683 "destination_count=" SIZE_FORMAT,
2684 cur_region, c->destination_count());
2685 issued_a_warning = true;
2686 }
2687 }
2688
2689 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2690 const RegionData* const c = sd.region(cur_region);
2691 if (!c->available()) {
2692 warning("region " SIZE_FORMAT " not empty: "
2693 "destination_count=" SIZE_FORMAT,
2694 cur_region, c->destination_count());
2695 issued_a_warning = true;
2696 }
2697 }
2698
2699 if (issued_a_warning) {
2700 print_region_ranges();
2701 }
2702 }
2703 #endif // #ifdef ASSERT
2704
2705 void PSParallelCompact::compact_serial(ParCompactionManager* cm) {
2706 EventMark m("5 compact serial");
2707 TraceTime tm("compact serial", print_phases(), true, gclog_or_tty);
2708
2709 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
2710 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
2711
2712 PSYoungGen* young_gen = heap->young_gen();
2713 PSOldGen* old_gen = heap->old_gen();
2714
2715 old_gen->start_array()->reset();
2716 old_gen->move_and_update(cm);
2717 young_gen->move_and_update(cm);
2718 }
2719
2720
2721 void PSParallelCompact::follow_stack(ParCompactionManager* cm) {
2722 while(!cm->overflow_stack()->is_empty()) {
2723 oop obj = cm->overflow_stack()->pop();
2724 obj->follow_contents(cm);
2725 }
2726
2727 oop obj;
2728 // obj is a reference!!!
2729 while (cm->marking_stack()->pop_local(obj)) {
2730 // It would be nice to assert about the type of objects we might
2731 // pop, but they can come from anywhere, unfortunately.
2732 obj->follow_contents(cm);
2733 }
2734 }
2735
2736 void
2737 PSParallelCompact::follow_weak_klass_links() {
2738 // All klasses on the revisit stack are marked at this point.
2739 // Update and follow all subklass, sibling and implementor links.
2740 if (PrintRevisitStats) {
2741 gclog_or_tty->print_cr("#classes in system dictionary = %d", SystemDictionary::number_of_classes());
2742 }
2743 for (uint i = 0; i < ParallelGCThreads + 1; i++) {
2744 ParCompactionManager* cm = ParCompactionManager::manager_array(i);
2745 KeepAliveClosure keep_alive_closure(cm);
2746 int length = cm->revisit_klass_stack()->length();
2747 if (PrintRevisitStats) {
2748 gclog_or_tty->print_cr("Revisit klass stack[%d] length = %d", i, length);
2749 }
2750 for (int j = 0; j < length; j++) {
2751 cm->revisit_klass_stack()->at(j)->follow_weak_klass_links(
2752 is_alive_closure(),
2753 &keep_alive_closure);
2754 }
2755 // revisit_klass_stack is cleared in reset()
2756 follow_stack(cm);
2757 }
2758 }
2759
2760 void
2761 PSParallelCompact::revisit_weak_klass_link(ParCompactionManager* cm, Klass* k) {
2762 cm->revisit_klass_stack()->push(k);
2763 }
2764
2765 void PSParallelCompact::revisit_mdo(ParCompactionManager* cm, DataLayout* p) {
2766 cm->revisit_mdo_stack()->push(p);
2767 }
2768
2769 void PSParallelCompact::follow_mdo_weak_refs() {
2770 // All strongly reachable oops have been marked at this point;
2771 // we can visit and clear any weak references from MDO's which
2772 // we memoized during the strong marking phase.
2773 if (PrintRevisitStats) {
2774 gclog_or_tty->print_cr("#classes in system dictionary = %d", SystemDictionary::number_of_classes());
2775 }
2776 for (uint i = 0; i < ParallelGCThreads + 1; i++) {
2777 ParCompactionManager* cm = ParCompactionManager::manager_array(i);
2778 GrowableArray<DataLayout*>* rms = cm->revisit_mdo_stack();
2779 int length = rms->length();
2780 if (PrintRevisitStats) {
2781 gclog_or_tty->print_cr("Revisit MDO stack[%d] length = %d", i, length);
2782 }
2783 for (int j = 0; j < length; j++) {
2784 rms->at(j)->follow_weak_refs(is_alive_closure());
2785 }
2786 // revisit_mdo_stack is cleared in reset()
2787 follow_stack(cm);
2788 }
2789 }
2790
2791
2792 #ifdef VALIDATE_MARK_SWEEP
2793
2794 void PSParallelCompact::track_adjusted_pointer(void* p, bool isroot) {
2795 if (!ValidateMarkSweep)
2796 return;
2797
2798 if (!isroot) {
2799 if (_pointer_tracking) {
2800 guarantee(_adjusted_pointers->contains(p), "should have seen this pointer");
2801 _adjusted_pointers->remove(p);
2802 }
2803 } else {
2804 ptrdiff_t index = _root_refs_stack->find(p);
2805 if (index != -1) {
2806 int l = _root_refs_stack->length();
2807 if (l > 0 && l - 1 != index) {
2808 void* last = _root_refs_stack->pop();
2809 assert(last != p, "should be different");
2810 _root_refs_stack->at_put(index, last);
2811 } else {
2812 _root_refs_stack->remove(p);
2813 }
2814 }
2815 }
2816 }
2817
2818
2819 void PSParallelCompact::check_adjust_pointer(void* p) {
2820 _adjusted_pointers->push(p);
2821 }
2822
2823
2824 class AdjusterTracker: public OopClosure {
2825 public:
2826 AdjusterTracker() {};
2827 void do_oop(oop* o) { PSParallelCompact::check_adjust_pointer(o); }
2828 void do_oop(narrowOop* o) { PSParallelCompact::check_adjust_pointer(o); }
2829 };
2830
2831
2832 void PSParallelCompact::track_interior_pointers(oop obj) {
2833 if (ValidateMarkSweep) {
2834 _adjusted_pointers->clear();
2835 _pointer_tracking = true;
2836
2837 AdjusterTracker checker;
2838 obj->oop_iterate(&checker);
2839 }
2840 }
2841
2842
2843 void PSParallelCompact::check_interior_pointers() {
2844 if (ValidateMarkSweep) {
2845 _pointer_tracking = false;
2846 guarantee(_adjusted_pointers->length() == 0, "should have processed the same pointers");
2847 }
2848 }
2849
2850
2851 void PSParallelCompact::reset_live_oop_tracking(bool at_perm) {
2852 if (ValidateMarkSweep) {
2853 guarantee((size_t)_live_oops->length() == _live_oops_index, "should be at end of live oops");
2854 _live_oops_index = at_perm ? _live_oops_index_at_perm : 0;
2855 }
2856 }
2857
2858
2859 void PSParallelCompact::register_live_oop(oop p, size_t size) {
2860 if (ValidateMarkSweep) {
2861 _live_oops->push(p);
2862 _live_oops_size->push(size);
2863 _live_oops_index++;
2864 }
2865 }
2866
2867 void PSParallelCompact::validate_live_oop(oop p, size_t size) {
2868 if (ValidateMarkSweep) {
2869 oop obj = _live_oops->at((int)_live_oops_index);
2870 guarantee(obj == p, "should be the same object");
2871 guarantee(_live_oops_size->at((int)_live_oops_index) == size, "should be the same size");
2872 _live_oops_index++;
2873 }
2874 }
2875
2876 void PSParallelCompact::live_oop_moved_to(HeapWord* q, size_t size,
2877 HeapWord* compaction_top) {
2878 assert(oop(q)->forwardee() == NULL || oop(q)->forwardee() == oop(compaction_top),
2879 "should be moved to forwarded location");
2880 if (ValidateMarkSweep) {
2881 PSParallelCompact::validate_live_oop(oop(q), size);
2882 _live_oops_moved_to->push(oop(compaction_top));
2883 }
2884 if (RecordMarkSweepCompaction) {
2885 _cur_gc_live_oops->push(q);
2886 _cur_gc_live_oops_moved_to->push(compaction_top);
2887 _cur_gc_live_oops_size->push(size);
2888 }
2889 }
2890
2891
2892 void PSParallelCompact::compaction_complete() {
2893 if (RecordMarkSweepCompaction) {
2894 GrowableArray<HeapWord*>* _tmp_live_oops = _cur_gc_live_oops;
2895 GrowableArray<HeapWord*>* _tmp_live_oops_moved_to = _cur_gc_live_oops_moved_to;
2896 GrowableArray<size_t> * _tmp_live_oops_size = _cur_gc_live_oops_size;
2897
2898 _cur_gc_live_oops = _last_gc_live_oops;
2899 _cur_gc_live_oops_moved_to = _last_gc_live_oops_moved_to;
2900 _cur_gc_live_oops_size = _last_gc_live_oops_size;
2901 _last_gc_live_oops = _tmp_live_oops;
2902 _last_gc_live_oops_moved_to = _tmp_live_oops_moved_to;
2903 _last_gc_live_oops_size = _tmp_live_oops_size;
2904 }
2905 }
2906
2907
2908 void PSParallelCompact::print_new_location_of_heap_address(HeapWord* q) {
2909 if (!RecordMarkSweepCompaction) {
2910 tty->print_cr("Requires RecordMarkSweepCompaction to be enabled");
2911 return;
2912 }
2913
2914 if (_last_gc_live_oops == NULL) {
2915 tty->print_cr("No compaction information gathered yet");
2916 return;
2917 }
2918
2919 for (int i = 0; i < _last_gc_live_oops->length(); i++) {
2920 HeapWord* old_oop = _last_gc_live_oops->at(i);
2921 size_t sz = _last_gc_live_oops_size->at(i);
2922 if (old_oop <= q && q < (old_oop + sz)) {
2923 HeapWord* new_oop = _last_gc_live_oops_moved_to->at(i);
2924 size_t offset = (q - old_oop);
2925 tty->print_cr("Address " PTR_FORMAT, q);
2926 tty->print_cr(" Was in oop " PTR_FORMAT ", size %d, at offset %d", old_oop, sz, offset);
2927 tty->print_cr(" Now in oop " PTR_FORMAT ", actual address " PTR_FORMAT, new_oop, new_oop + offset);
2928 return;
2929 }
2930 }
2931
2932 tty->print_cr("Address " PTR_FORMAT " not found in live oop information from last GC", q);
2933 }
2934 #endif //VALIDATE_MARK_SWEEP
2935
2936 // Update interior oops in the ranges of regions [beg_region, end_region).
2937 void
2938 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2939 SpaceId space_id,
2940 size_t beg_region,
2941 size_t end_region) {
2942 ParallelCompactData& sd = summary_data();
2943 ParMarkBitMap* const mbm = mark_bitmap();
2944
2945 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2946 HeapWord* const end_addr = sd.region_to_addr(end_region);
2947 assert(beg_region <= end_region, "bad region range");
2948 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2949
2950 #ifdef ASSERT
2951 // Claim the regions to avoid triggering an assert when they are marked as
2952 // filled.
2953 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2954 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2955 }
2956 #endif // #ifdef ASSERT
2957
2958 if (beg_addr != space(space_id)->bottom()) {
2959 // Find the first live object or block of dead space that *starts* in this
2960 // range of regions. If a partial object crosses onto the region, skip it;
2961 // it will be marked for 'deferred update' when the object head is
2962 // processed. If dead space crosses onto the region, it is also skipped; it
2963 // will be filled when the prior region is processed. If neither of those
2964 // apply, the first word in the region is the start of a live object or dead
2965 // space.
2966 assert(beg_addr > space(space_id)->bottom(), "sanity");
2967 const RegionData* const cp = sd.region(beg_region);
2968 if (cp->partial_obj_size() != 0) {
2969 beg_addr = sd.partial_obj_end(beg_region);
2970 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2971 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2972 }
2973 }
2974
2975 if (beg_addr < end_addr) {
2976 // A live object or block of dead space starts in this range of Regions.
2977 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2978
2979 // Create closures and iterate.
2980 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2981 FillClosure fill_closure(cm, space_id);
2982 ParMarkBitMap::IterationStatus status;
2983 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2984 dense_prefix_end);
2985 if (status == ParMarkBitMap::incomplete) {
2986 update_closure.do_addr(update_closure.source());
2987 }
2988 }
2989
2990 // Mark the regions as filled.
2991 RegionData* const beg_cp = sd.region(beg_region);
2992 RegionData* const end_cp = sd.region(end_region);
2993 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2994 cp->set_completed();
2995 }
2996 }
2997
2998 // Return the SpaceId for the space containing addr. If addr is not in the
2999 // heap, last_space_id is returned. In debug mode it expects the address to be
3000 // in the heap and asserts such.
3001 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
3002 assert(Universe::heap()->is_in_reserved(addr), "addr not in the heap");
3003
3004 for (unsigned int id = perm_space_id; id < last_space_id; ++id) {
3005 if (_space_info[id].space()->contains(addr)) {
3006 return SpaceId(id);
3007 }
3008 }
3009
3010 assert(false, "no space contains the addr");
3011 return last_space_id;
3012 }
3013
3014 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
3015 SpaceId id) {
3016 assert(id < last_space_id, "bad space id");
3017
3018 ParallelCompactData& sd = summary_data();
3019 const SpaceInfo* const space_info = _space_info + id;
3020 ObjectStartArray* const start_array = space_info->start_array();
3021
3022 const MutableSpace* const space = space_info->space();
3023 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
3024 HeapWord* const beg_addr = space_info->dense_prefix();
3025 HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
3026
3027 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
3028 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
3029 const RegionData* cur_region;
3030 for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
3031 HeapWord* const addr = cur_region->deferred_obj_addr();
3032 if (addr != NULL) {
3033 if (start_array != NULL) {
3034 start_array->allocate_block(addr);
3035 }
3036 oop(addr)->update_contents(cm);
3037 assert(oop(addr)->is_oop_or_null(), "should be an oop now");
3038 }
3039 }
3040 }
3041
3042 // Skip over count live words starting from beg, and return the address of the
3043 // next live word. Unless marked, the word corresponding to beg is assumed to
3044 // be dead. Callers must either ensure beg does not correspond to the middle of
3045 // an object, or account for those live words in some other way. Callers must
3046 // also ensure that there are enough live words in the range [beg, end) to skip.
3047 HeapWord*
3048 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
3049 {
3050 assert(count > 0, "sanity");
3051
3052 ParMarkBitMap* m = mark_bitmap();
3053 idx_t bits_to_skip = m->words_to_bits(count);
3054 idx_t cur_beg = m->addr_to_bit(beg);
3055 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
3056
3057 do {
3058 cur_beg = m->find_obj_beg(cur_beg, search_end);
3059 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
3060 const size_t obj_bits = cur_end - cur_beg + 1;
3061 if (obj_bits > bits_to_skip) {
3062 return m->bit_to_addr(cur_beg + bits_to_skip);
3063 }
3064 bits_to_skip -= obj_bits;
3065 cur_beg = cur_end + 1;
3066 } while (bits_to_skip > 0);
3067
3068 // Skipping the desired number of words landed just past the end of an object.
3069 // Find the start of the next object.
3070 cur_beg = m->find_obj_beg(cur_beg, search_end);
3071 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
3072 return m->bit_to_addr(cur_beg);
3073 }
3074
3075 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
3076 SpaceId src_space_id,
3077 size_t src_region_idx)
3078 {
3079 assert(summary_data().is_region_aligned(dest_addr), "not aligned");
3080
3081 const SplitInfo& split_info = _space_info[src_space_id].split_info();
3082 if (split_info.dest_region_addr() == dest_addr) {
3083 // The partial object ending at the split point contains the first word to
3084 // be copied to dest_addr.
3085 return split_info.first_src_addr();
3086 }
3087
3088 const ParallelCompactData& sd = summary_data();
3089 ParMarkBitMap* const bitmap = mark_bitmap();
3090 const size_t RegionSize = ParallelCompactData::RegionSize;
3091
3092 assert(sd.is_region_aligned(dest_addr), "not aligned");
3093 const RegionData* const src_region_ptr = sd.region(src_region_idx);
3094 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
3095 HeapWord* const src_region_destination = src_region_ptr->destination();
3096
3097 assert(dest_addr >= src_region_destination, "wrong src region");
3098 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
3099
3100 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
3101 HeapWord* const src_region_end = src_region_beg + RegionSize;
3102
3103 HeapWord* addr = src_region_beg;
3104 if (dest_addr == src_region_destination) {
3105 // Return the first live word in the source region.
3106 if (partial_obj_size == 0) {
3107 addr = bitmap->find_obj_beg(addr, src_region_end);
3108 assert(addr < src_region_end, "no objects start in src region");
3109 }
3110 return addr;
3111 }
3112
3113 // Must skip some live data.
3114 size_t words_to_skip = dest_addr - src_region_destination;
3115 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
3116
3117 if (partial_obj_size >= words_to_skip) {
3118 // All the live words to skip are part of the partial object.
3119 addr += words_to_skip;
3120 if (partial_obj_size == words_to_skip) {
3121 // Find the first live word past the partial object.
3122 addr = bitmap->find_obj_beg(addr, src_region_end);
3123 assert(addr < src_region_end, "wrong src region");
3124 }
3125 return addr;
3126 }
3127
3128 // Skip over the partial object (if any).
3129 if (partial_obj_size != 0) {
3130 words_to_skip -= partial_obj_size;
3131 addr += partial_obj_size;
3132 }
3133
3134 // Skip over live words due to objects that start in the region.
3135 addr = skip_live_words(addr, src_region_end, words_to_skip);
3136 assert(addr < src_region_end, "wrong src region");
3137 return addr;
3138 }
3139
3140 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
3141 SpaceId src_space_id,
3142 size_t beg_region,
3143 HeapWord* end_addr)
3144 {
3145 ParallelCompactData& sd = summary_data();
3146
3147 #ifdef ASSERT
3148 MutableSpace* const src_space = _space_info[src_space_id].space();
3149 HeapWord* const beg_addr = sd.region_to_addr(beg_region);
3150 assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
3151 "src_space_id does not match beg_addr");
3152 assert(src_space->contains(end_addr) || end_addr == src_space->end(),
3153 "src_space_id does not match end_addr");
3154 #endif // #ifdef ASSERT
3155
3156 RegionData* const beg = sd.region(beg_region);
3157 RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
3158
3159 // Regions up to new_top() are enqueued if they become available.
3160 HeapWord* const new_top = _space_info[src_space_id].new_top();
3161 RegionData* const enqueue_end =
3162 sd.addr_to_region_ptr(sd.region_align_up(new_top));
3163
3164 for (RegionData* cur = beg; cur < end; ++cur) {
3165 assert(cur->data_size() > 0, "region must have live data");
3166 cur->decrement_destination_count();
3167 if (cur < enqueue_end && cur->available() && cur->claim()) {
3168 cm->save_for_processing(sd.region(cur));
3169 }
3170 }
3171 }
3172
3173 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
3174 SpaceId& src_space_id,
3175 HeapWord*& src_space_top,
3176 HeapWord* end_addr)
3177 {
3178 typedef ParallelCompactData::RegionData RegionData;
3179
3180 ParallelCompactData& sd = PSParallelCompact::summary_data();
3181 const size_t region_size = ParallelCompactData::RegionSize;
3182
3183 size_t src_region_idx = 0;
3184
3185 // Skip empty regions (if any) up to the top of the space.
3186 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
3187 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
3188 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
3189 const RegionData* const top_region_ptr =
3190 sd.addr_to_region_ptr(top_aligned_up);
3191 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
3192 ++src_region_ptr;
3193 }
3194
3195 if (src_region_ptr < top_region_ptr) {
3196 // The next source region is in the current space. Update src_region_idx
3197 // and the source address to match src_region_ptr.
3198 src_region_idx = sd.region(src_region_ptr);
3199 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
3200 if (src_region_addr > closure.source()) {
3201 closure.set_source(src_region_addr);
3202 }
3203 return src_region_idx;
3204 }
3205
3206 // Switch to a new source space and find the first non-empty region.
3207 unsigned int space_id = src_space_id + 1;
3208 assert(space_id < last_space_id, "not enough spaces");
3209
3210 HeapWord* const destination = closure.destination();
3211
3212 do {
3213 MutableSpace* space = _space_info[space_id].space();
3214 HeapWord* const bottom = space->bottom();
3215 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
3216
3217 // Iterate over the spaces that do not compact into themselves.
3218 if (bottom_cp->destination() != bottom) {
3219 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
3220 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
3221
3222 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
3223 if (src_cp->live_obj_size() > 0) {
3224 // Found it.
3225 assert(src_cp->destination() == destination,
3226 "first live obj in the space must match the destination");
3227 assert(src_cp->partial_obj_size() == 0,
3228 "a space cannot begin with a partial obj");
3229
3230 src_space_id = SpaceId(space_id);
3231 src_space_top = space->top();
3232 const size_t src_region_idx = sd.region(src_cp);
3233 closure.set_source(sd.region_to_addr(src_region_idx));
3234 return src_region_idx;
3235 } else {
3236 assert(src_cp->data_size() == 0, "sanity");
3237 }
3238 }
3239 }
3240 } while (++space_id < last_space_id);
3241
3242 assert(false, "no source region was found");
3243 return 0;
3244 }
3245
3246 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
3247 {
3248 typedef ParMarkBitMap::IterationStatus IterationStatus;
3249 const size_t RegionSize = ParallelCompactData::RegionSize;
3250 ParMarkBitMap* const bitmap = mark_bitmap();
3251 ParallelCompactData& sd = summary_data();
3252 RegionData* const region_ptr = sd.region(region_idx);
3253
3254 // Get the items needed to construct the closure.
3255 HeapWord* dest_addr = sd.region_to_addr(region_idx);
3256 SpaceId dest_space_id = space_id(dest_addr);
3257 ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
3258 HeapWord* new_top = _space_info[dest_space_id].new_top();
3259 assert(dest_addr < new_top, "sanity");
3260 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
3261
3262 // Get the source region and related info.
3263 size_t src_region_idx = region_ptr->source_region();
3264 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
3265 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
3266
3267 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3268 closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
3269
3270 // Adjust src_region_idx to prepare for decrementing destination counts (the
3271 // destination count is not decremented when a region is copied to itself).
3272 if (src_region_idx == region_idx) {
3273 src_region_idx += 1;
3274 }
3275
3276 if (bitmap->is_unmarked(closure.source())) {
3277 // The first source word is in the middle of an object; copy the remainder
3278 // of the object or as much as will fit. The fact that pointer updates were
3279 // deferred will be noted when the object header is processed.
3280 HeapWord* const old_src_addr = closure.source();
3281 closure.copy_partial_obj();
3282 if (closure.is_full()) {
3283 decrement_destination_counts(cm, src_space_id, src_region_idx,
3284 closure.source());
3285 region_ptr->set_deferred_obj_addr(NULL);
3286 region_ptr->set_completed();
3287 return;
3288 }
3289
3290 HeapWord* const end_addr = sd.region_align_down(closure.source());
3291 if (sd.region_align_down(old_src_addr) != end_addr) {
3292 // The partial object was copied from more than one source region.
3293 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3294
3295 // Move to the next source region, possibly switching spaces as well. All
3296 // args except end_addr may be modified.
3297 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3298 end_addr);
3299 }
3300 }
3301
3302 do {
3303 HeapWord* const cur_addr = closure.source();
3304 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
3305 src_space_top);
3306 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
3307
3308 if (status == ParMarkBitMap::incomplete) {
3309 // The last obj that starts in the source region does not end in the
3310 // region.
3311 assert(closure.source() < end_addr, "sanity")
3312 HeapWord* const obj_beg = closure.source();
3313 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
3314 src_space_top);
3315 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
3316 if (obj_end < range_end) {
3317 // The end was found; the entire object will fit.
3318 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
3319 assert(status != ParMarkBitMap::would_overflow, "sanity");
3320 } else {
3321 // The end was not found; the object will not fit.
3322 assert(range_end < src_space_top, "obj cannot cross space boundary");
3323 status = ParMarkBitMap::would_overflow;
3324 }
3325 }
3326
3327 if (status == ParMarkBitMap::would_overflow) {
3328 // The last object did not fit. Note that interior oop updates were
3329 // deferred, then copy enough of the object to fill the region.
3330 region_ptr->set_deferred_obj_addr(closure.destination());
3331 status = closure.copy_until_full(); // copies from closure.source()
3332
3333 decrement_destination_counts(cm, src_space_id, src_region_idx,
3334 closure.source());
3335 region_ptr->set_completed();
3336 return;
3337 }
3338
3339 if (status == ParMarkBitMap::full) {
3340 decrement_destination_counts(cm, src_space_id, src_region_idx,
3341 closure.source());
3342 region_ptr->set_deferred_obj_addr(NULL);
3343 region_ptr->set_completed();
3344 return;
3345 }
3346
3347 decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3348
3349 // Move to the next source region, possibly switching spaces as well. All
3350 // args except end_addr may be modified.
3351 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3352 end_addr);
3353 } while (true);
3354 }
3355
3356 void
3357 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
3358 const MutableSpace* sp = space(space_id);
3359 if (sp->is_empty()) {
3360 return;
3361 }
3362
3363 ParallelCompactData& sd = PSParallelCompact::summary_data();
3364 ParMarkBitMap* const bitmap = mark_bitmap();
3365 HeapWord* const dp_addr = dense_prefix(space_id);
3366 HeapWord* beg_addr = sp->bottom();
3367 HeapWord* end_addr = sp->top();
3368
3369 #ifdef ASSERT
3370 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
3371 if (cm->should_verify_only()) {
3372 VerifyUpdateClosure verify_update(cm, sp);
3373 bitmap->iterate(&verify_update, beg_addr, end_addr);
3374 return;
3375 }
3376
3377 if (cm->should_reset_only()) {
3378 ResetObjectsClosure reset_objects(cm);
3379 bitmap->iterate(&reset_objects, beg_addr, end_addr);
3380 return;
3381 }
3382 #endif
3383
3384 const size_t beg_region = sd.addr_to_region_idx(beg_addr);
3385 const size_t dp_region = sd.addr_to_region_idx(dp_addr);
3386 if (beg_region < dp_region) {
3387 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
3388 }
3389
3390 // The destination of the first live object that starts in the region is one
3391 // past the end of the partial object entering the region (if any).
3392 HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3393 HeapWord* const new_top = _space_info[space_id].new_top();
3394 assert(new_top >= dest_addr, "bad new_top value");
3395 const size_t words = pointer_delta(new_top, dest_addr);
3396
3397 if (words > 0) {
3398 ObjectStartArray* start_array = _space_info[space_id].start_array();
3399 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3400
3401 ParMarkBitMap::IterationStatus status;
3402 status = bitmap->iterate(&closure, dest_addr, end_addr);
3403 assert(status == ParMarkBitMap::full, "iteration not complete");
3404 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3405 "live objects skipped because closure is full");
3406 }
3407 }
3408
3409 jlong PSParallelCompact::millis_since_last_gc() {
3410 jlong ret_val = os::javaTimeMillis() - _time_of_last_gc;
3411 // XXX See note in genCollectedHeap::millis_since_last_gc().
3412 if (ret_val < 0) {
3413 NOT_PRODUCT(warning("time warp: %d", ret_val);)
3414 return 0;
3415 }
3416 return ret_val;
3417 }
3418
3419 void PSParallelCompact::reset_millis_since_last_gc() {
3420 _time_of_last_gc = os::javaTimeMillis();
3421 }
3422
3423 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3424 {
3425 if (source() != destination()) {
3426 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3427 Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3428 }
3429 update_state(words_remaining());
3430 assert(is_full(), "sanity");
3431 return ParMarkBitMap::full;
3432 }
3433
3434 void MoveAndUpdateClosure::copy_partial_obj()
3435 {
3436 size_t words = words_remaining();
3437
3438 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3439 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3440 if (end_addr < range_end) {
3441 words = bitmap()->obj_size(source(), end_addr);
3442 }
3443
3444 // This test is necessary; if omitted, the pointer updates to a partial object
3445 // that crosses the dense prefix boundary could be overwritten.
3446 if (source() != destination()) {
3447 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3448 Copy::aligned_conjoint_words(source(), destination(), words);
3449 }
3450 update_state(words);
3451 }
3452
3453 ParMarkBitMapClosure::IterationStatus
3454 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3455 assert(destination() != NULL, "sanity");
3456 assert(bitmap()->obj_size(addr) == words, "bad size");
3457
3458 _source = addr;
3459 assert(PSParallelCompact::summary_data().calc_new_pointer(source()) ==
3460 destination(), "wrong destination");
3461
3462 if (words > words_remaining()) {
3463 return ParMarkBitMap::would_overflow;
3464 }
3465
3466 // The start_array must be updated even if the object is not moving.
3467 if (_start_array != NULL) {
3468 _start_array->allocate_block(destination());
3469 }
3470
3471 if (destination() != source()) {
3472 DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3473 Copy::aligned_conjoint_words(source(), destination(), words);
3474 }
3475
3476 oop moved_oop = (oop) destination();
3477 moved_oop->update_contents(compaction_manager());
3478 assert(moved_oop->is_oop_or_null(), "Object should be whole at this point");
3479
3480 update_state(words);
3481 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3482 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3483 }
3484
3485 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3486 ParCompactionManager* cm,
3487 PSParallelCompact::SpaceId space_id) :
3488 ParMarkBitMapClosure(mbm, cm),
3489 _space_id(space_id),
3490 _start_array(PSParallelCompact::start_array(space_id))
3491 {
3492 }
3493
3494 // Updates the references in the object to their new values.
3495 ParMarkBitMapClosure::IterationStatus
3496 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3497 do_addr(addr);
3498 return ParMarkBitMap::incomplete;
3499 }
3500
3501 // Verify the new location using the forwarding pointer
3502 // from MarkSweep::mark_sweep_phase2(). Set the mark_word
3503 // to the initial value.
3504 ParMarkBitMapClosure::IterationStatus
3505 PSParallelCompact::VerifyUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3506 // The second arg (words) is not used.
3507 oop obj = (oop) addr;
3508 HeapWord* forwarding_ptr = (HeapWord*) obj->mark()->decode_pointer();
3509 HeapWord* new_pointer = summary_data().calc_new_pointer(obj);
3510 if (forwarding_ptr == NULL) {
3511 // The object is dead or not moving.
3512 assert(bitmap()->is_unmarked(obj) || (new_pointer == (HeapWord*) obj),
3513 "Object liveness is wrong.");
3514 return ParMarkBitMap::incomplete;
3515 }
3516 assert(UseParallelOldGCDensePrefix ||
3517 (HeapMaximumCompactionInterval > 1) ||
3518 (MarkSweepAlwaysCompactCount > 1) ||
3519 (forwarding_ptr == new_pointer),
3520 "Calculation of new location is incorrect");
3521 return ParMarkBitMap::incomplete;
3522 }
3523
3524 // Reset objects modified for debug checking.
3525 ParMarkBitMapClosure::IterationStatus
3526 PSParallelCompact::ResetObjectsClosure::do_addr(HeapWord* addr, size_t words) {
3527 // The second arg (words) is not used.
3528 oop obj = (oop) addr;
3529 obj->init_mark();
3530 return ParMarkBitMap::incomplete;
3531 }
3532
3533 // Prepare for compaction. This method is executed once
3534 // (i.e., by a single thread) before compaction.
3535 // Save the updated location of the intArrayKlassObj for
3536 // filling holes in the dense prefix.
3537 void PSParallelCompact::compact_prologue() {
3538 _updated_int_array_klass_obj = (klassOop)
3539 summary_data().calc_new_pointer(Universe::intArrayKlassObj());
3540 }
3541