1 /*
2 * Copyright 2005-2008 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 #ifndef PRODUCT
92 const char* PSParallelCompact::space_names[] = {
93 "perm", "old ", "eden", "from", "to "
94 };
95
96 void PSParallelCompact::print_region_ranges()
97 {
98 tty->print_cr("space bottom top end new_top");
99 tty->print_cr("------ ---------- ---------- ---------- ----------");
100
101 for (unsigned int id = 0; id < last_space_id; ++id) {
102 const MutableSpace* space = _space_info[id].space();
103 tty->print_cr("%u %s "
104 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
105 SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
106 id, space_names[id],
107 summary_data().addr_to_region_idx(space->bottom()),
108 summary_data().addr_to_region_idx(space->top()),
109 summary_data().addr_to_region_idx(space->end()),
110 summary_data().addr_to_region_idx(_space_info[id].new_top()));
111 }
112 }
113
114 void
115 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
116 {
117 #define REGION_IDX_FORMAT SIZE_FORMAT_W(7)
118 #define REGION_DATA_FORMAT SIZE_FORMAT_W(5)
119
120 ParallelCompactData& sd = PSParallelCompact::summary_data();
121 size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
122 tty->print_cr(REGION_IDX_FORMAT " " PTR_FORMAT " "
123 REGION_IDX_FORMAT " " PTR_FORMAT " "
124 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
125 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
126 i, c->data_location(), dci, c->destination(),
127 c->partial_obj_size(), c->live_obj_size(),
128 c->data_size(), c->source_region(), c->destination_count());
129
130 #undef REGION_IDX_FORMAT
131 #undef REGION_DATA_FORMAT
132 }
133
134 void
135 print_generic_summary_data(ParallelCompactData& summary_data,
136 HeapWord* const beg_addr,
137 HeapWord* const end_addr)
138 {
139 size_t total_words = 0;
140 size_t i = summary_data.addr_to_region_idx(beg_addr);
141 const size_t last = summary_data.addr_to_region_idx(end_addr);
142 HeapWord* pdest = 0;
143
144 while (i <= last) {
145 ParallelCompactData::RegionData* c = summary_data.region(i);
146 if (c->data_size() != 0 || c->destination() != pdest) {
147 print_generic_summary_region(i, c);
148 total_words += c->data_size();
149 pdest = c->destination();
150 }
151 ++i;
152 }
153
154 tty->print_cr("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
155 }
156
157 void
158 print_generic_summary_data(ParallelCompactData& summary_data,
159 SpaceInfo* space_info)
160 {
161 for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
162 const MutableSpace* space = space_info[id].space();
163 print_generic_summary_data(summary_data, space->bottom(),
164 MAX2(space->top(), space_info[id].new_top()));
165 }
166 }
167
168 void
169 print_initial_summary_region(size_t i,
170 const ParallelCompactData::RegionData* c,
171 bool newline = true)
172 {
173 tty->print(SIZE_FORMAT_W(5) " " PTR_FORMAT " "
174 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " "
175 SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
176 i, c->destination(),
177 c->partial_obj_size(), c->live_obj_size(),
178 c->data_size(), c->source_region(), c->destination_count());
179 if (newline) tty->cr();
180 }
181
182 void
183 print_initial_summary_data(ParallelCompactData& summary_data,
184 const MutableSpace* space) {
185 if (space->top() == space->bottom()) {
186 return;
187 }
188
189 const size_t region_size = ParallelCompactData::RegionSize;
190 typedef ParallelCompactData::RegionData RegionData;
191 HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
192 const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
193 const RegionData* c = summary_data.region(end_region - 1);
194 HeapWord* end_addr = c->destination() + c->data_size();
195 const size_t live_in_space = pointer_delta(end_addr, space->bottom());
196
197 // Print (and count) the full regions at the beginning of the space.
198 size_t full_region_count = 0;
199 size_t i = summary_data.addr_to_region_idx(space->bottom());
200 while (i < end_region && summary_data.region(i)->data_size() == region_size) {
201 print_initial_summary_region(i, summary_data.region(i));
202 ++full_region_count;
203 ++i;
204 }
205
206 size_t live_to_right = live_in_space - full_region_count * region_size;
207
208 double max_reclaimed_ratio = 0.0;
209 size_t max_reclaimed_ratio_region = 0;
210 size_t max_dead_to_right = 0;
211 size_t max_live_to_right = 0;
212
213 // Print the 'reclaimed ratio' for regions while there is something live in
214 // the region or to the right of it. The remaining regions are empty (and
215 // uninteresting), and computing the ratio will result in division by 0.
216 while (i < end_region && live_to_right > 0) {
217 c = summary_data.region(i);
218 HeapWord* const region_addr = summary_data.region_to_addr(i);
219 const size_t used_to_right = pointer_delta(space->top(), region_addr);
220 const size_t dead_to_right = used_to_right - live_to_right;
221 const double reclaimed_ratio = double(dead_to_right) / live_to_right;
222
223 if (reclaimed_ratio > max_reclaimed_ratio) {
224 max_reclaimed_ratio = reclaimed_ratio;
225 max_reclaimed_ratio_region = i;
226 max_dead_to_right = dead_to_right;
227 max_live_to_right = live_to_right;
228 }
229
230 print_initial_summary_region(i, c, false);
231 tty->print_cr(" %12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
232 reclaimed_ratio, dead_to_right, live_to_right);
233
234 live_to_right -= c->data_size();
235 ++i;
236 }
237
238 // Any remaining regions are empty. Print one more if there is one.
239 if (i < end_region) {
240 print_initial_summary_region(i, summary_data.region(i));
241 }
242
243 tty->print_cr("max: " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " "
244 "l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
245 max_reclaimed_ratio_region, max_dead_to_right,
246 max_live_to_right, max_reclaimed_ratio);
247 }
248
249 void
250 print_initial_summary_data(ParallelCompactData& summary_data,
251 SpaceInfo* space_info) {
252 unsigned int id = PSParallelCompact::perm_space_id;
253 const MutableSpace* space;
254 do {
255 space = space_info[id].space();
256 print_initial_summary_data(summary_data, space);
257 } while (++id < PSParallelCompact::eden_space_id);
258
259 do {
260 space = space_info[id].space();
261 print_generic_summary_data(summary_data, space->bottom(), space->top());
262 } while (++id < PSParallelCompact::last_space_id);
263 }
264 #endif // #ifndef PRODUCT
265
266 #ifdef ASSERT
267 size_t add_obj_count;
268 size_t add_obj_size;
269 size_t mark_bitmap_count;
270 size_t mark_bitmap_size;
271 #endif // #ifdef ASSERT
272
273 ParallelCompactData::ParallelCompactData()
274 {
275 _region_start = 0;
276
277 _region_vspace = 0;
278 _region_data = 0;
279 _region_count = 0;
280 }
281
282 bool ParallelCompactData::initialize(MemRegion covered_region)
283 {
284 _region_start = covered_region.start();
285 const size_t region_size = covered_region.word_size();
286 DEBUG_ONLY(_region_end = _region_start + region_size;)
287
288 assert(region_align_down(_region_start) == _region_start,
289 "region start not aligned");
290 assert((region_size & RegionSizeOffsetMask) == 0,
291 "region size not a multiple of RegionSize");
292
293 bool result = initialize_region_data(region_size);
294
295 return result;
296 }
297
298 PSVirtualSpace*
299 ParallelCompactData::create_vspace(size_t count, size_t element_size)
300 {
301 const size_t raw_bytes = count * element_size;
302 const size_t page_sz = os::page_size_for_region(raw_bytes, raw_bytes, 10);
303 const size_t granularity = os::vm_allocation_granularity();
304 const size_t bytes = align_size_up(raw_bytes, MAX2(page_sz, granularity));
305
306 const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
307 MAX2(page_sz, granularity);
308 ReservedSpace rs(bytes, rs_align, rs_align > 0);
309 os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(),
310 rs.size());
311 PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
312 if (vspace != 0) {
313 if (vspace->expand_by(bytes)) {
314 return vspace;
315 }
316 delete vspace;
317 // Release memory reserved in the space.
318 rs.release();
319 }
320
321 return 0;
322 }
323
324 bool ParallelCompactData::initialize_region_data(size_t region_size)
325 {
326 const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
327 _region_vspace = create_vspace(count, sizeof(RegionData));
328 if (_region_vspace != 0) {
329 _region_data = (RegionData*)_region_vspace->reserved_low_addr();
330 _region_count = count;
331 return true;
332 }
333 return false;
334 }
335
336 void ParallelCompactData::clear()
337 {
338 memset(_region_data, 0, _region_vspace->committed_size());
339 }
340
341 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
342 assert(beg_region <= _region_count, "beg_region out of range");
343 assert(end_region <= _region_count, "end_region out of range");
344
345 const size_t region_cnt = end_region - beg_region;
346 memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
347 }
348
349 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
350 {
351 const RegionData* cur_cp = region(region_idx);
352 const RegionData* const end_cp = region(region_count() - 1);
353
354 HeapWord* result = region_to_addr(region_idx);
355 if (cur_cp < end_cp) {
356 do {
357 result += cur_cp->partial_obj_size();
358 } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
359 }
360 return result;
361 }
362
363 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
364 {
365 const size_t obj_ofs = pointer_delta(addr, _region_start);
366 const size_t beg_region = obj_ofs >> Log2RegionSize;
367 const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
368
369 DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
370 DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
371
372 if (beg_region == end_region) {
373 // All in one region.
374 _region_data[beg_region].add_live_obj(len);
375 return;
376 }
377
378 // First region.
379 const size_t beg_ofs = region_offset(addr);
380 _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
381
382 klassOop klass = ((oop)addr)->klass();
383 // Middle regions--completely spanned by this object.
384 for (size_t region = beg_region + 1; region < end_region; ++region) {
385 _region_data[region].set_partial_obj_size(RegionSize);
386 _region_data[region].set_partial_obj_addr(addr);
387 }
388
389 // Last region.
390 const size_t end_ofs = region_offset(addr + len - 1);
391 _region_data[end_region].set_partial_obj_size(end_ofs + 1);
392 _region_data[end_region].set_partial_obj_addr(addr);
393 }
394
395 void
396 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
397 {
398 assert(region_offset(beg) == 0, "not RegionSize aligned");
399 assert(region_offset(end) == 0, "not RegionSize aligned");
400
401 size_t cur_region = addr_to_region_idx(beg);
402 const size_t end_region = addr_to_region_idx(end);
403 HeapWord* addr = beg;
404 while (cur_region < end_region) {
405 _region_data[cur_region].set_destination(addr);
406 _region_data[cur_region].set_destination_count(0);
407 _region_data[cur_region].set_source_region(cur_region);
408 _region_data[cur_region].set_data_location(addr);
409
410 // Update live_obj_size so the region appears completely full.
411 size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
412 _region_data[cur_region].set_live_obj_size(live_size);
413
414 ++cur_region;
415 addr += RegionSize;
416 }
417 }
418
419 bool ParallelCompactData::summarize(HeapWord* target_beg, HeapWord* target_end,
420 HeapWord* source_beg, HeapWord* source_end,
421 HeapWord** target_next,
422 HeapWord** source_next) {
423 // This is too strict.
424 // assert(region_offset(source_beg) == 0, "not RegionSize aligned");
425
426 if (TraceParallelOldGCSummaryPhase) {
427 tty->print_cr("tb=" PTR_FORMAT " te=" PTR_FORMAT " "
428 "sb=" PTR_FORMAT " se=" PTR_FORMAT " "
429 "tn=" PTR_FORMAT " sn=" PTR_FORMAT,
430 target_beg, target_end,
431 source_beg, source_end,
432 target_next != 0 ? *target_next : (HeapWord*) 0,
433 source_next != 0 ? *source_next : (HeapWord*) 0);
434 }
435
436 size_t cur_region = addr_to_region_idx(source_beg);
437 const size_t end_region = addr_to_region_idx(region_align_up(source_end));
438
439 HeapWord *dest_addr = target_beg;
440 while (cur_region < end_region) {
441 size_t words = _region_data[cur_region].data_size();
442
443 #if 1
444 assert(pointer_delta(target_end, dest_addr) >= words,
445 "source region does not fit into target region");
446 #else
447 // XXX - need some work on the corner cases here. If the region does not
448 // fit, then must either make sure any partial_obj from the region fits, or
449 // "undo" the initial part of the partial_obj that is in the previous
450 // region.
451 if (dest_addr + words >= target_end) {
452 // Let the caller know where to continue.
453 *target_next = dest_addr;
454 *source_next = region_to_addr(cur_region);
455 return false;
456 }
457 #endif // #if 1
458
459 _region_data[cur_region].set_destination(dest_addr);
460
461 // Set the destination_count for cur_region, and if necessary, update
462 // source_region for a destination region. The source_region field is
463 // updated if cur_region is the first (left-most) region to be copied to a
464 // destination region.
465 //
466 // The destination_count calculation is a bit subtle. A region that has
467 // data that compacts into itself does not count itself as a destination.
468 // This maintains the invariant that a zero count means the region is
469 // available and can be claimed and then filled.
470 if (words > 0) {
471 HeapWord* const last_addr = dest_addr + words - 1;
472 const size_t dest_region_1 = addr_to_region_idx(dest_addr);
473 const size_t dest_region_2 = addr_to_region_idx(last_addr);
474 #if 0
475 // Initially assume that the destination regions will be the same and
476 // adjust the value below if necessary. Under this assumption, if
477 // cur_region == dest_region_2, then cur_region will be compacted
478 // completely into itself.
479 uint destination_count = cur_region == dest_region_2 ? 0 : 1;
480 if (dest_region_1 != dest_region_2) {
481 // Destination regions differ; adjust destination_count.
482 destination_count += 1;
483 // Data from cur_region will be copied to the start of dest_region_2.
484 _region_data[dest_region_2].set_source_region(cur_region);
485 } else if (region_offset(dest_addr) == 0) {
486 // Data from cur_region will be copied to the start of the destination
487 // region.
488 _region_data[dest_region_1].set_source_region(cur_region);
489 }
490 #else
491 // Initially assume that the destination regions will be different and
492 // adjust the value below if necessary. Under this assumption, if
493 // cur_region == dest_region2, then cur_region will be compacted partially
494 // into dest_region_1 and partially into itself.
495 uint destination_count = cur_region == dest_region_2 ? 1 : 2;
496 if (dest_region_1 != dest_region_2) {
497 // Data from cur_region will be copied to the start of dest_region_2.
498 _region_data[dest_region_2].set_source_region(cur_region);
499 } else {
500 // Destination regions are the same; adjust destination_count.
501 destination_count -= 1;
502 if (region_offset(dest_addr) == 0) {
503 // Data from cur_region will be copied to the start of the destination
504 // region.
505 _region_data[dest_region_1].set_source_region(cur_region);
506 }
507 }
508 #endif // #if 0
509
510 _region_data[cur_region].set_destination_count(destination_count);
511 _region_data[cur_region].set_data_location(region_to_addr(cur_region));
512 dest_addr += words;
513 }
514
515 ++cur_region;
516 }
517
518 *target_next = dest_addr;
519 return true;
520 }
521
522 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) {
523 assert(addr != NULL, "Should detect NULL oop earlier");
524 assert(PSParallelCompact::gc_heap()->is_in(addr), "addr not in heap");
525 #ifdef ASSERT
526 if (PSParallelCompact::mark_bitmap()->is_unmarked(addr)) {
527 gclog_or_tty->print_cr("calc_new_pointer:: addr " PTR_FORMAT, addr);
528 }
529 #endif
530 assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "obj not marked");
531
532 // Region covering the object.
533 size_t region_index = addr_to_region_idx(addr);
534 const RegionData* const region_ptr = region(region_index);
535 HeapWord* const region_addr = region_align_down(addr);
536
537 assert(addr < region_addr + RegionSize, "Region does not cover object");
538 assert(addr_to_region_ptr(region_addr) == region_ptr, "sanity check");
539
540 HeapWord* result = region_ptr->destination();
541
542 // If all the data in the region is live, then the new location of the object
543 // can be calculated from the destination of the region plus the offset of the
544 // object in the region.
545 if (region_ptr->data_size() == RegionSize) {
546 result += pointer_delta(addr, region_addr);
547 return result;
548 }
549
550 // The new location of the object is
551 // region destination +
552 // size of the partial object extending onto the region +
553 // sizes of the live objects in the Region that are to the left of addr
554 const size_t partial_obj_size = region_ptr->partial_obj_size();
555 HeapWord* const search_start = region_addr + partial_obj_size;
556
557 const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
558 size_t live_to_left = bitmap->live_words_in_range(search_start, oop(addr));
559
560 result += partial_obj_size + live_to_left;
561 assert(result <= addr, "object cannot move to the right");
562 return result;
563 }
564
565 klassOop ParallelCompactData::calc_new_klass(klassOop old_klass) {
566 klassOop updated_klass;
567 if (PSParallelCompact::should_update_klass(old_klass)) {
568 updated_klass = (klassOop) calc_new_pointer(old_klass);
569 } else {
570 updated_klass = old_klass;
571 }
572
573 return updated_klass;
574 }
575
576 #ifdef ASSERT
577 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
578 {
579 const size_t* const beg = (const size_t*)vspace->committed_low_addr();
580 const size_t* const end = (const size_t*)vspace->committed_high_addr();
581 for (const size_t* p = beg; p < end; ++p) {
582 assert(*p == 0, "not zero");
583 }
584 }
585
586 void ParallelCompactData::verify_clear()
587 {
588 verify_clear(_region_vspace);
589 }
590 #endif // #ifdef ASSERT
591
592 #ifdef NOT_PRODUCT
593 ParallelCompactData::RegionData* debug_region(size_t region_index) {
594 ParallelCompactData& sd = PSParallelCompact::summary_data();
595 return sd.region(region_index);
596 }
597 #endif
598
599 elapsedTimer PSParallelCompact::_accumulated_time;
600 unsigned int PSParallelCompact::_total_invocations = 0;
601 unsigned int PSParallelCompact::_maximum_compaction_gc_num = 0;
602 jlong PSParallelCompact::_time_of_last_gc = 0;
603 CollectorCounters* PSParallelCompact::_counters = NULL;
604 ParMarkBitMap PSParallelCompact::_mark_bitmap;
605 ParallelCompactData PSParallelCompact::_summary_data;
606
607 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
608
609 void PSParallelCompact::IsAliveClosure::do_object(oop p) { ShouldNotReachHere(); }
610 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
611
612 void PSParallelCompact::KeepAliveClosure::do_oop(oop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
613 void PSParallelCompact::KeepAliveClosure::do_oop(narrowOop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
614
615 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_root_pointer_closure(true);
616 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_pointer_closure(false);
617
618 void PSParallelCompact::AdjustPointerClosure::do_oop(oop* p) { adjust_pointer(p, _is_root); }
619 void PSParallelCompact::AdjustPointerClosure::do_oop(narrowOop* p) { adjust_pointer(p, _is_root); }
620
621 void PSParallelCompact::FollowStackClosure::do_void() { follow_stack(_compaction_manager); }
622
623 void PSParallelCompact::MarkAndPushClosure::do_oop(oop* p) { mark_and_push(_compaction_manager, p); }
624 void PSParallelCompact::MarkAndPushClosure::do_oop(narrowOop* p) { mark_and_push(_compaction_manager, p); }
625
626 void PSParallelCompact::post_initialize() {
627 ParallelScavengeHeap* heap = gc_heap();
628 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
629
630 MemRegion mr = heap->reserved_region();
631 _ref_processor = ReferenceProcessor::create_ref_processor(
632 mr, // span
633 true, // atomic_discovery
634 true, // mt_discovery
635 &_is_alive_closure,
636 ParallelGCThreads,
637 ParallelRefProcEnabled);
638 _counters = new CollectorCounters("PSParallelCompact", 1);
639
640 // Initialize static fields in ParCompactionManager.
641 ParCompactionManager::initialize(mark_bitmap());
642 }
643
644 bool PSParallelCompact::initialize() {
645 ParallelScavengeHeap* heap = gc_heap();
646 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
647 MemRegion mr = heap->reserved_region();
648
649 // Was the old gen get allocated successfully?
650 if (!heap->old_gen()->is_allocated()) {
651 return false;
652 }
653
654 initialize_space_info();
655 initialize_dead_wood_limiter();
656
657 if (!_mark_bitmap.initialize(mr)) {
658 vm_shutdown_during_initialization("Unable to allocate bit map for "
659 "parallel garbage collection for the requested heap size.");
660 return false;
661 }
662
663 if (!_summary_data.initialize(mr)) {
664 vm_shutdown_during_initialization("Unable to allocate tables for "
665 "parallel garbage collection for the requested heap size.");
666 return false;
667 }
668
669 return true;
670 }
671
672 void PSParallelCompact::initialize_space_info()
673 {
674 memset(&_space_info, 0, sizeof(_space_info));
675
676 ParallelScavengeHeap* heap = gc_heap();
677 PSYoungGen* young_gen = heap->young_gen();
678 MutableSpace* perm_space = heap->perm_gen()->object_space();
679
680 _space_info[perm_space_id].set_space(perm_space);
681 _space_info[old_space_id].set_space(heap->old_gen()->object_space());
682 _space_info[eden_space_id].set_space(young_gen->eden_space());
683 _space_info[from_space_id].set_space(young_gen->from_space());
684 _space_info[to_space_id].set_space(young_gen->to_space());
685
686 _space_info[perm_space_id].set_start_array(heap->perm_gen()->start_array());
687 _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
688
689 _space_info[perm_space_id].set_min_dense_prefix(perm_space->top());
690 if (TraceParallelOldGCDensePrefix) {
691 tty->print_cr("perm min_dense_prefix=" PTR_FORMAT,
692 _space_info[perm_space_id].min_dense_prefix());
693 }
694 }
695
696 void PSParallelCompact::initialize_dead_wood_limiter()
697 {
698 const size_t max = 100;
699 _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
700 _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
701 _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
702 DEBUG_ONLY(_dwl_initialized = true;)
703 _dwl_adjustment = normal_distribution(1.0);
704 }
705
706 // Simple class for storing info about the heap at the start of GC, to be used
707 // after GC for comparison/printing.
708 class PreGCValues {
709 public:
710 PreGCValues() { }
711 PreGCValues(ParallelScavengeHeap* heap) { fill(heap); }
712
713 void fill(ParallelScavengeHeap* heap) {
714 _heap_used = heap->used();
715 _young_gen_used = heap->young_gen()->used_in_bytes();
716 _old_gen_used = heap->old_gen()->used_in_bytes();
717 _perm_gen_used = heap->perm_gen()->used_in_bytes();
718 };
719
720 size_t heap_used() const { return _heap_used; }
721 size_t young_gen_used() const { return _young_gen_used; }
722 size_t old_gen_used() const { return _old_gen_used; }
723 size_t perm_gen_used() const { return _perm_gen_used; }
724
725 private:
726 size_t _heap_used;
727 size_t _young_gen_used;
728 size_t _old_gen_used;
729 size_t _perm_gen_used;
730 };
731
732 void
733 PSParallelCompact::clear_data_covering_space(SpaceId id)
734 {
735 // At this point, top is the value before GC, new_top() is the value that will
736 // be set at the end of GC. The marking bitmap is cleared to top; nothing
737 // should be marked above top. The summary data is cleared to the larger of
738 // top & new_top.
739 MutableSpace* const space = _space_info[id].space();
740 HeapWord* const bot = space->bottom();
741 HeapWord* const top = space->top();
742 HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
743
744 const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
745 const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
746 _mark_bitmap.clear_range(beg_bit, end_bit);
747
748 const size_t beg_region = _summary_data.addr_to_region_idx(bot);
749 const size_t end_region =
750 _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
751 _summary_data.clear_range(beg_region, end_region);
752 }
753
754 void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values)
755 {
756 // Update the from & to space pointers in space_info, since they are swapped
757 // at each young gen gc. Do the update unconditionally (even though a
758 // promotion failure does not swap spaces) because an unknown number of minor
759 // collections will have swapped the spaces an unknown number of times.
760 TraceTime tm("pre compact", print_phases(), true, gclog_or_tty);
761 ParallelScavengeHeap* heap = gc_heap();
762 _space_info[from_space_id].set_space(heap->young_gen()->from_space());
763 _space_info[to_space_id].set_space(heap->young_gen()->to_space());
764
765 pre_gc_values->fill(heap);
766
767 ParCompactionManager::reset();
768 NOT_PRODUCT(_mark_bitmap.reset_counters());
769 DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
770 DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
771
772 // Increment the invocation count
773 heap->increment_total_collections(true);
774
775 // We need to track unique mark sweep invocations as well.
776 _total_invocations++;
777
778 if (PrintHeapAtGC) {
779 Universe::print_heap_before_gc();
780 }
781
782 // Fill in TLABs
783 heap->accumulate_statistics_all_tlabs();
784 heap->ensure_parsability(true); // retire TLABs
785
786 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
787 HandleMark hm; // Discard invalid handles created during verification
788 gclog_or_tty->print(" VerifyBeforeGC:");
789 Universe::verify(true);
790 }
791
792 // Verify object start arrays
793 if (VerifyObjectStartArray &&
794 VerifyBeforeGC) {
795 heap->old_gen()->verify_object_start_array();
796 heap->perm_gen()->verify_object_start_array();
797 }
798
799 DEBUG_ONLY(mark_bitmap()->verify_clear();)
800 DEBUG_ONLY(summary_data().verify_clear();)
801
802 // Have worker threads release resources the next time they run a task.
803 gc_task_manager()->release_all_resources();
804 }
805
806 void PSParallelCompact::post_compact()
807 {
808 TraceTime tm("post compact", print_phases(), true, gclog_or_tty);
809
810 // Clear the marking bitmap and summary data and update top() in each space.
811 for (unsigned int id = perm_space_id; id < last_space_id; ++id) {
812 clear_data_covering_space(SpaceId(id));
813 _space_info[id].space()->set_top(_space_info[id].new_top());
814 }
815
816 MutableSpace* const eden_space = _space_info[eden_space_id].space();
817 MutableSpace* const from_space = _space_info[from_space_id].space();
818 MutableSpace* const to_space = _space_info[to_space_id].space();
819
820 ParallelScavengeHeap* heap = gc_heap();
821 bool eden_empty = eden_space->is_empty();
822 if (!eden_empty) {
823 eden_empty = absorb_live_data_from_eden(heap->size_policy(),
824 heap->young_gen(), heap->old_gen());
825 }
826
827 // Update heap occupancy information which is used as input to the soft ref
828 // clearing policy at the next gc.
829 Universe::update_heap_info_at_gc();
830
831 bool young_gen_empty = eden_empty && from_space->is_empty() &&
832 to_space->is_empty();
833
834 BarrierSet* bs = heap->barrier_set();
835 if (bs->is_a(BarrierSet::ModRef)) {
836 ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
837 MemRegion old_mr = heap->old_gen()->reserved();
838 MemRegion perm_mr = heap->perm_gen()->reserved();
839 assert(perm_mr.end() <= old_mr.start(), "Generations out of order");
840
841 if (young_gen_empty) {
842 modBS->clear(MemRegion(perm_mr.start(), old_mr.end()));
843 } else {
844 modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end()));
845 }
846 }
847
848 Threads::gc_epilogue();
849 CodeCache::gc_epilogue();
850
851 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
852
853 ref_processor()->enqueue_discovered_references(NULL);
854
855 if (ZapUnusedHeapArea) {
856 heap->gen_mangle_unused_area();
857 }
858
859 // Update time of last GC
860 reset_millis_since_last_gc();
861 }
862
863 HeapWord*
864 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
865 bool maximum_compaction)
866 {
867 const size_t region_size = ParallelCompactData::RegionSize;
868 const ParallelCompactData& sd = summary_data();
869
870 const MutableSpace* const space = _space_info[id].space();
871 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
872 const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
873 const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
874
875 // Skip full regions at the beginning of the space--they are necessarily part
876 // of the dense prefix.
877 size_t full_count = 0;
878 const RegionData* cp;
879 for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
880 ++full_count;
881 }
882
883 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
884 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
885 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
886 if (maximum_compaction || cp == end_cp || interval_ended) {
887 _maximum_compaction_gc_num = total_invocations();
888 return sd.region_to_addr(cp);
889 }
890
891 HeapWord* const new_top = _space_info[id].new_top();
892 const size_t space_live = pointer_delta(new_top, space->bottom());
893 const size_t space_used = space->used_in_words();
894 const size_t space_capacity = space->capacity_in_words();
895
896 const double cur_density = double(space_live) / space_capacity;
897 const double deadwood_density =
898 (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
899 const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
900
901 if (TraceParallelOldGCDensePrefix) {
902 tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
903 cur_density, deadwood_density, deadwood_goal);
904 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
905 "space_cap=" SIZE_FORMAT,
906 space_live, space_used,
907 space_capacity);
908 }
909
910 // XXX - Use binary search?
911 HeapWord* dense_prefix = sd.region_to_addr(cp);
912 const RegionData* full_cp = cp;
913 const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
914 while (cp < end_cp) {
915 HeapWord* region_destination = cp->destination();
916 const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
917 if (TraceParallelOldGCDensePrefix && Verbose) {
918 tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
919 "dp=" SIZE_FORMAT_W(8) " " "cdw=" SIZE_FORMAT_W(8),
920 sd.region(cp), region_destination,
921 dense_prefix, cur_deadwood);
922 }
923
924 if (cur_deadwood >= deadwood_goal) {
925 // Found the region that has the correct amount of deadwood to the left.
926 // This typically occurs after crossing a fairly sparse set of regions, so
927 // iterate backwards over those sparse regions, looking for the region
928 // that has the lowest density of live objects 'to the right.'
929 size_t space_to_left = sd.region(cp) * region_size;
930 size_t live_to_left = space_to_left - cur_deadwood;
931 size_t space_to_right = space_capacity - space_to_left;
932 size_t live_to_right = space_live - live_to_left;
933 double density_to_right = double(live_to_right) / space_to_right;
934 while (cp > full_cp) {
935 --cp;
936 const size_t prev_region_live_to_right = live_to_right -
937 cp->data_size();
938 const size_t prev_region_space_to_right = space_to_right + region_size;
939 double prev_region_density_to_right =
940 double(prev_region_live_to_right) / prev_region_space_to_right;
941 if (density_to_right <= prev_region_density_to_right) {
942 return dense_prefix;
943 }
944 if (TraceParallelOldGCDensePrefix && Verbose) {
945 tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
946 "pc_d2r=%10.8f", sd.region(cp), density_to_right,
947 prev_region_density_to_right);
948 }
949 dense_prefix -= region_size;
950 live_to_right = prev_region_live_to_right;
951 space_to_right = prev_region_space_to_right;
952 density_to_right = prev_region_density_to_right;
953 }
954 return dense_prefix;
955 }
956
957 dense_prefix += region_size;
958 ++cp;
959 }
960
961 return dense_prefix;
962 }
963
964 #ifndef PRODUCT
965 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
966 const SpaceId id,
967 const bool maximum_compaction,
968 HeapWord* const addr)
969 {
970 const size_t region_idx = summary_data().addr_to_region_idx(addr);
971 RegionData* const cp = summary_data().region(region_idx);
972 const MutableSpace* const space = _space_info[id].space();
973 HeapWord* const new_top = _space_info[id].new_top();
974
975 const size_t space_live = pointer_delta(new_top, space->bottom());
976 const size_t dead_to_left = pointer_delta(addr, cp->destination());
977 const size_t space_cap = space->capacity_in_words();
978 const double dead_to_left_pct = double(dead_to_left) / space_cap;
979 const size_t live_to_right = new_top - cp->destination();
980 const size_t dead_to_right = space->top() - addr - live_to_right;
981
982 tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
983 "spl=" SIZE_FORMAT " "
984 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
985 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
986 " ratio=%10.8f",
987 algorithm, addr, region_idx,
988 space_live,
989 dead_to_left, dead_to_left_pct,
990 dead_to_right, live_to_right,
991 double(dead_to_right) / live_to_right);
992 }
993 #endif // #ifndef PRODUCT
994
995 // Return a fraction indicating how much of the generation can be treated as
996 // "dead wood" (i.e., not reclaimed). The function uses a normal distribution
997 // based on the density of live objects in the generation to determine a limit,
998 // which is then adjusted so the return value is min_percent when the density is
999 // 1.
1000 //
1001 // The following table shows some return values for a different values of the
1002 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1003 // min_percent is 1.
1004 //
1005 // fraction allowed as dead wood
1006 // -----------------------------------------------------------------
1007 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1008 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1009 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1010 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1011 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1012 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1013 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1014 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1015 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1016 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1017 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1018 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1019 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1020 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1021 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1022 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1023 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1024 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1025 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1026 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1027 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1028 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1029 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1030
1031 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1032 {
1033 assert(_dwl_initialized, "uninitialized");
1034
1035 // The raw limit is the value of the normal distribution at x = density.
1036 const double raw_limit = normal_distribution(density);
1037
1038 // Adjust the raw limit so it becomes the minimum when the density is 1.
1039 //
1040 // First subtract the adjustment value (which is simply the precomputed value
1041 // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1042 // Then add the minimum value, so the minimum is returned when the density is
1043 // 1. Finally, prevent negative values, which occur when the mean is not 0.5.
1044 const double min = double(min_percent) / 100.0;
1045 const double limit = raw_limit - _dwl_adjustment + min;
1046 return MAX2(limit, 0.0);
1047 }
1048
1049 ParallelCompactData::RegionData*
1050 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1051 const RegionData* end)
1052 {
1053 const size_t region_size = ParallelCompactData::RegionSize;
1054 ParallelCompactData& sd = summary_data();
1055 size_t left = sd.region(beg);
1056 size_t right = end > beg ? sd.region(end) - 1 : left;
1057
1058 // Binary search.
1059 while (left < right) {
1060 // Equivalent to (left + right) / 2, but does not overflow.
1061 const size_t middle = left + (right - left) / 2;
1062 RegionData* const middle_ptr = sd.region(middle);
1063 HeapWord* const dest = middle_ptr->destination();
1064 HeapWord* const addr = sd.region_to_addr(middle);
1065 assert(dest != NULL, "sanity");
1066 assert(dest <= addr, "must move left");
1067
1068 if (middle > left && dest < addr) {
1069 right = middle - 1;
1070 } else if (middle < right && middle_ptr->data_size() == region_size) {
1071 left = middle + 1;
1072 } else {
1073 return middle_ptr;
1074 }
1075 }
1076 return sd.region(left);
1077 }
1078
1079 ParallelCompactData::RegionData*
1080 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1081 const RegionData* end,
1082 size_t dead_words)
1083 {
1084 ParallelCompactData& sd = summary_data();
1085 size_t left = sd.region(beg);
1086 size_t right = end > beg ? sd.region(end) - 1 : left;
1087
1088 // Binary search.
1089 while (left < right) {
1090 // Equivalent to (left + right) / 2, but does not overflow.
1091 const size_t middle = left + (right - left) / 2;
1092 RegionData* const middle_ptr = sd.region(middle);
1093 HeapWord* const dest = middle_ptr->destination();
1094 HeapWord* const addr = sd.region_to_addr(middle);
1095 assert(dest != NULL, "sanity");
1096 assert(dest <= addr, "must move left");
1097
1098 const size_t dead_to_left = pointer_delta(addr, dest);
1099 if (middle > left && dead_to_left > dead_words) {
1100 right = middle - 1;
1101 } else if (middle < right && dead_to_left < dead_words) {
1102 left = middle + 1;
1103 } else {
1104 return middle_ptr;
1105 }
1106 }
1107 return sd.region(left);
1108 }
1109
1110 // The result is valid during the summary phase, after the initial summarization
1111 // of each space into itself, and before final summarization.
1112 inline double
1113 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1114 HeapWord* const bottom,
1115 HeapWord* const top,
1116 HeapWord* const new_top)
1117 {
1118 ParallelCompactData& sd = summary_data();
1119
1120 assert(cp != NULL, "sanity");
1121 assert(bottom != NULL, "sanity");
1122 assert(top != NULL, "sanity");
1123 assert(new_top != NULL, "sanity");
1124 assert(top >= new_top, "summary data problem?");
1125 assert(new_top > bottom, "space is empty; should not be here");
1126 assert(new_top >= cp->destination(), "sanity");
1127 assert(top >= sd.region_to_addr(cp), "sanity");
1128
1129 HeapWord* const destination = cp->destination();
1130 const size_t dense_prefix_live = pointer_delta(destination, bottom);
1131 const size_t compacted_region_live = pointer_delta(new_top, destination);
1132 const size_t compacted_region_used = pointer_delta(top,
1133 sd.region_to_addr(cp));
1134 const size_t reclaimable = compacted_region_used - compacted_region_live;
1135
1136 const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1137 return double(reclaimable) / divisor;
1138 }
1139
1140 // Return the address of the end of the dense prefix, a.k.a. the start of the
1141 // compacted region. The address is always on a region boundary.
1142 //
1143 // Completely full regions at the left are skipped, since no compaction can
1144 // occur in those regions. Then the maximum amount of dead wood to allow is
1145 // computed, based on the density (amount live / capacity) of the generation;
1146 // the region with approximately that amount of dead space to the left is
1147 // identified as the limit region. Regions between the last completely full
1148 // region and the limit region are scanned and the one that has the best
1149 // (maximum) reclaimed_ratio() is selected.
1150 HeapWord*
1151 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1152 bool maximum_compaction)
1153 {
1154 const size_t region_size = ParallelCompactData::RegionSize;
1155 const ParallelCompactData& sd = summary_data();
1156
1157 const MutableSpace* const space = _space_info[id].space();
1158 HeapWord* const top = space->top();
1159 HeapWord* const top_aligned_up = sd.region_align_up(top);
1160 HeapWord* const new_top = _space_info[id].new_top();
1161 HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1162 HeapWord* const bottom = space->bottom();
1163 const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1164 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1165 const RegionData* const new_top_cp =
1166 sd.addr_to_region_ptr(new_top_aligned_up);
1167
1168 // Skip full regions at the beginning of the space--they are necessarily part
1169 // of the dense prefix.
1170 const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1171 assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1172 space->is_empty(), "no dead space allowed to the left");
1173 assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1174 "region must have dead space");
1175
1176 // The gc number is saved whenever a maximum compaction is done, and used to
1177 // determine when the maximum compaction interval has expired. This avoids
1178 // successive max compactions for different reasons.
1179 assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1180 const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1181 const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1182 total_invocations() == HeapFirstMaximumCompactionCount;
1183 if (maximum_compaction || full_cp == top_cp || interval_ended) {
1184 _maximum_compaction_gc_num = total_invocations();
1185 return sd.region_to_addr(full_cp);
1186 }
1187
1188 const size_t space_live = pointer_delta(new_top, bottom);
1189 const size_t space_used = space->used_in_words();
1190 const size_t space_capacity = space->capacity_in_words();
1191
1192 const double density = double(space_live) / double(space_capacity);
1193 const size_t min_percent_free =
1194 id == perm_space_id ? PermMarkSweepDeadRatio : MarkSweepDeadRatio;
1195 const double limiter = dead_wood_limiter(density, min_percent_free);
1196 const size_t dead_wood_max = space_used - space_live;
1197 const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1198 dead_wood_max);
1199
1200 if (TraceParallelOldGCDensePrefix) {
1201 tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1202 "space_cap=" SIZE_FORMAT,
1203 space_live, space_used,
1204 space_capacity);
1205 tty->print_cr("dead_wood_limiter(%6.4f, %d)=%6.4f "
1206 "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1207 density, min_percent_free, limiter,
1208 dead_wood_max, dead_wood_limit);
1209 }
1210
1211 // Locate the region with the desired amount of dead space to the left.
1212 const RegionData* const limit_cp =
1213 dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1214
1215 // Scan from the first region with dead space to the limit region and find the
1216 // one with the best (largest) reclaimed ratio.
1217 double best_ratio = 0.0;
1218 const RegionData* best_cp = full_cp;
1219 for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1220 double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1221 if (tmp_ratio > best_ratio) {
1222 best_cp = cp;
1223 best_ratio = tmp_ratio;
1224 }
1225 }
1226
1227 #if 0
1228 // Something to consider: if the region with the best ratio is 'close to' the
1229 // first region w/free space, choose the first region with free space
1230 // ("first-free"). The first-free region is usually near the start of the
1231 // heap, which means we are copying most of the heap already, so copy a bit
1232 // more to get complete compaction.
1233 if (pointer_delta(best_cp, full_cp, sizeof(RegionData)) < 4) {
1234 _maximum_compaction_gc_num = total_invocations();
1235 best_cp = full_cp;
1236 }
1237 #endif // #if 0
1238
1239 return sd.region_to_addr(best_cp);
1240 }
1241
1242 void PSParallelCompact::summarize_spaces_quick()
1243 {
1244 for (unsigned int i = 0; i < last_space_id; ++i) {
1245 const MutableSpace* space = _space_info[i].space();
1246 bool result = _summary_data.summarize(space->bottom(), space->end(),
1247 space->bottom(), space->top(),
1248 _space_info[i].new_top_addr());
1249 assert(result, "should never fail");
1250 _space_info[i].set_dense_prefix(space->bottom());
1251 }
1252 }
1253
1254 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1255 {
1256 HeapWord* const dense_prefix_end = dense_prefix(id);
1257 const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1258 const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1259 if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1260 // Only enough dead space is filled so that any remaining dead space to the
1261 // left is larger than the minimum filler object. (The remainder is filled
1262 // during the copy/update phase.)
1263 //
1264 // The size of the dead space to the right of the boundary is not a
1265 // concern, since compaction will be able to use whatever space is
1266 // available.
1267 //
1268 // Here '||' is the boundary, 'x' represents a don't care bit and a box
1269 // surrounds the space to be filled with an object.
1270 //
1271 // In the 32-bit VM, each bit represents two 32-bit words:
1272 // +---+
1273 // a) beg_bits: ... x x x | 0 | || 0 x x ...
1274 // end_bits: ... x x x | 0 | || 0 x x ...
1275 // +---+
1276 //
1277 // In the 64-bit VM, each bit represents one 64-bit word:
1278 // +------------+
1279 // b) beg_bits: ... x x x | 0 || 0 | x x ...
1280 // end_bits: ... x x 1 | 0 || 0 | x x ...
1281 // +------------+
1282 // +-------+
1283 // c) beg_bits: ... x x | 0 0 | || 0 x x ...
1284 // end_bits: ... x 1 | 0 0 | || 0 x x ...
1285 // +-------+
1286 // +-----------+
1287 // d) beg_bits: ... x | 0 0 0 | || 0 x x ...
1288 // end_bits: ... 1 | 0 0 0 | || 0 x x ...
1289 // +-----------+
1290 // +-------+
1291 // e) beg_bits: ... 0 0 | 0 0 | || 0 x x ...
1292 // end_bits: ... 0 0 | 0 0 | || 0 x x ...
1293 // +-------+
1294
1295 // Initially assume case a, c or e will apply.
1296 size_t obj_len = (size_t)oopDesc::header_size();
1297 HeapWord* obj_beg = dense_prefix_end - obj_len;
1298
1299 #ifdef _LP64
1300 if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1301 // Case b above.
1302 obj_beg = dense_prefix_end - 1;
1303 } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1304 _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1305 // Case d above.
1306 obj_beg = dense_prefix_end - 3;
1307 obj_len = 3;
1308 }
1309 #endif // #ifdef _LP64
1310
1311 MemRegion region(obj_beg, obj_len);
1312 SharedHeap::fill_region_with_object(region);
1313 _mark_bitmap.mark_obj(obj_beg, obj_len);
1314 _summary_data.add_obj(obj_beg, obj_len);
1315 assert(start_array(id) != NULL, "sanity");
1316 start_array(id)->allocate_block(obj_beg);
1317 }
1318 }
1319
1320 void
1321 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1322 {
1323 assert(id < last_space_id, "id out of range");
1324 assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(),
1325 "should have been set in summarize_spaces_quick()");
1326
1327 const MutableSpace* space = _space_info[id].space();
1328 if (_space_info[id].new_top() != space->bottom()) {
1329 HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1330 _space_info[id].set_dense_prefix(dense_prefix_end);
1331
1332 #ifndef PRODUCT
1333 if (TraceParallelOldGCDensePrefix) {
1334 print_dense_prefix_stats("ratio", id, maximum_compaction,
1335 dense_prefix_end);
1336 HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1337 print_dense_prefix_stats("density", id, maximum_compaction, addr);
1338 }
1339 #endif // #ifndef PRODUCT
1340
1341 // If dead space crosses the dense prefix boundary, it is (at least
1342 // partially) filled with a dummy object, marked live and added to the
1343 // summary data. This simplifies the copy/update phase and must be done
1344 // before the final locations of objects are determined, to prevent leaving
1345 // a fragment of dead space that is too small to fill with an object.
1346 if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1347 fill_dense_prefix_end(id);
1348 }
1349
1350 // Compute the destination of each Region, and thus each object.
1351 _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1352 _summary_data.summarize(dense_prefix_end, space->end(),
1353 dense_prefix_end, space->top(),
1354 _space_info[id].new_top_addr());
1355 }
1356
1357 if (TraceParallelOldGCSummaryPhase) {
1358 const size_t region_size = ParallelCompactData::RegionSize;
1359 HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1360 const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1361 const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1362 HeapWord* const new_top = _space_info[id].new_top();
1363 const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1364 const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1365 tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1366 "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1367 "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1368 id, space->capacity_in_words(), dense_prefix_end,
1369 dp_region, dp_words / region_size,
1370 cr_words / region_size, new_top);
1371 }
1372 }
1373
1374 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1375 bool maximum_compaction)
1376 {
1377 EventMark m("2 summarize");
1378 TraceTime tm("summary phase", print_phases(), true, gclog_or_tty);
1379 // trace("2");
1380
1381 #ifdef ASSERT
1382 if (TraceParallelOldGCMarkingPhase) {
1383 tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1384 "add_obj_bytes=" SIZE_FORMAT,
1385 add_obj_count, add_obj_size * HeapWordSize);
1386 tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1387 "mark_bitmap_bytes=" SIZE_FORMAT,
1388 mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1389 }
1390 #endif // #ifdef ASSERT
1391
1392 // Quick summarization of each space into itself, to see how much is live.
1393 summarize_spaces_quick();
1394
1395 if (TraceParallelOldGCSummaryPhase) {
1396 tty->print_cr("summary_phase: after summarizing each space to self");
1397 Universe::print();
1398 NOT_PRODUCT(print_region_ranges());
1399 if (Verbose) {
1400 NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1401 }
1402 }
1403
1404 // The amount of live data that will end up in old space (assuming it fits).
1405 size_t old_space_total_live = 0;
1406 unsigned int id;
1407 for (id = old_space_id; id < last_space_id; ++id) {
1408 old_space_total_live += pointer_delta(_space_info[id].new_top(),
1409 _space_info[id].space()->bottom());
1410 }
1411
1412 const MutableSpace* old_space = _space_info[old_space_id].space();
1413 if (old_space_total_live > old_space->capacity_in_words()) {
1414 // XXX - should also try to expand
1415 maximum_compaction = true;
1416 } else if (!UseParallelOldGCDensePrefix) {
1417 maximum_compaction = true;
1418 }
1419
1420 // Permanent and Old generations.
1421 summarize_space(perm_space_id, maximum_compaction);
1422 summarize_space(old_space_id, maximum_compaction);
1423
1424 // Summarize the remaining spaces (those in the young gen) into old space. If
1425 // the live data from a space doesn't fit, the existing summarization is left
1426 // intact, so the data is compacted down within the space itself.
1427 HeapWord** new_top_addr = _space_info[old_space_id].new_top_addr();
1428 HeapWord* const target_space_end = old_space->end();
1429 for (id = eden_space_id; id < last_space_id; ++id) {
1430 const MutableSpace* space = _space_info[id].space();
1431 const size_t live = pointer_delta(_space_info[id].new_top(),
1432 space->bottom());
1433 const size_t available = pointer_delta(target_space_end, *new_top_addr);
1434 if (live > 0 && live <= available) {
1435 // All the live data will fit.
1436 if (TraceParallelOldGCSummaryPhase) {
1437 tty->print_cr("summarizing %d into old_space @ " PTR_FORMAT,
1438 id, *new_top_addr);
1439 }
1440 _summary_data.summarize(*new_top_addr, target_space_end,
1441 space->bottom(), space->top(),
1442 new_top_addr);
1443
1444 // Clear the source_region field for each region in the space.
1445 HeapWord* const new_top = _space_info[id].new_top();
1446 HeapWord* const clear_end = _summary_data.region_align_up(new_top);
1447 RegionData* beg_region =
1448 _summary_data.addr_to_region_ptr(space->bottom());
1449 RegionData* end_region = _summary_data.addr_to_region_ptr(clear_end);
1450 while (beg_region < end_region) {
1451 beg_region->set_source_region(0);
1452 ++beg_region;
1453 }
1454
1455 // Reset the new_top value for the space.
1456 _space_info[id].set_new_top(space->bottom());
1457 }
1458 }
1459
1460 if (TraceParallelOldGCSummaryPhase) {
1461 tty->print_cr("summary_phase: after final summarization");
1462 Universe::print();
1463 NOT_PRODUCT(print_region_ranges());
1464 if (Verbose) {
1465 NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info));
1466 }
1467 }
1468 }
1469
1470 // This method should contain all heap-specific policy for invoking a full
1471 // collection. invoke_no_policy() will only attempt to compact the heap; it
1472 // will do nothing further. If we need to bail out for policy reasons, scavenge
1473 // before full gc, or any other specialized behavior, it needs to be added here.
1474 //
1475 // Note that this method should only be called from the vm_thread while at a
1476 // safepoint.
1477 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1478 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1479 assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1480 "should be in vm thread");
1481 ParallelScavengeHeap* heap = gc_heap();
1482 GCCause::Cause gc_cause = heap->gc_cause();
1483 assert(!heap->is_gc_active(), "not reentrant");
1484
1485 PSAdaptiveSizePolicy* policy = heap->size_policy();
1486
1487 // Before each allocation/collection attempt, find out from the
1488 // policy object if GCs are, on the whole, taking too long. If so,
1489 // bail out without attempting a collection. The exceptions are
1490 // for explicitly requested GC's.
1491 if (!policy->gc_time_limit_exceeded() ||
1492 GCCause::is_user_requested_gc(gc_cause) ||
1493 GCCause::is_serviceability_requested_gc(gc_cause)) {
1494 IsGCActiveMark mark;
1495
1496 if (ScavengeBeforeFullGC) {
1497 PSScavenge::invoke_no_policy();
1498 }
1499
1500 PSParallelCompact::invoke_no_policy(maximum_heap_compaction);
1501 }
1502 }
1503
1504 bool ParallelCompactData::region_contains(size_t region_index, HeapWord* addr) {
1505 size_t addr_region_index = addr_to_region_idx(addr);
1506 return region_index == addr_region_index;
1507 }
1508
1509 // This method contains no policy. You should probably
1510 // be calling invoke() instead.
1511 void PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1512 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1513 assert(ref_processor() != NULL, "Sanity");
1514
1515 if (GC_locker::check_active_before_gc()) {
1516 return;
1517 }
1518
1519 TimeStamp marking_start;
1520 TimeStamp compaction_start;
1521 TimeStamp collection_exit;
1522
1523 ParallelScavengeHeap* heap = gc_heap();
1524 GCCause::Cause gc_cause = heap->gc_cause();
1525 PSYoungGen* young_gen = heap->young_gen();
1526 PSOldGen* old_gen = heap->old_gen();
1527 PSPermGen* perm_gen = heap->perm_gen();
1528 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1529
1530 if (ZapUnusedHeapArea) {
1531 // Save information needed to minimize mangling
1532 heap->record_gen_tops_before_GC();
1533 }
1534
1535 _print_phases = PrintGCDetails && PrintParallelOldGCPhaseTimes;
1536
1537 // Make sure data structures are sane, make the heap parsable, and do other
1538 // miscellaneous bookkeeping.
1539 PreGCValues pre_gc_values;
1540 pre_compact(&pre_gc_values);
1541
1542 // Get the compaction manager reserved for the VM thread.
1543 ParCompactionManager* const vmthread_cm =
1544 ParCompactionManager::manager_array(gc_task_manager()->workers());
1545
1546 // Place after pre_compact() where the number of invocations is incremented.
1547 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
1548
1549 {
1550 ResourceMark rm;
1551 HandleMark hm;
1552
1553 const bool is_system_gc = gc_cause == GCCause::_java_lang_system_gc;
1554
1555 // This is useful for debugging but don't change the output the
1556 // the customer sees.
1557 const char* gc_cause_str = "Full GC";
1558 if (is_system_gc && PrintGCDetails) {
1559 gc_cause_str = "Full GC (System)";
1560 }
1561 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
1562 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
1563 TraceTime t1(gc_cause_str, PrintGC, !PrintGCDetails, gclog_or_tty);
1564 TraceCollectorStats tcs(counters());
1565 TraceMemoryManagerStats tms(true /* Full GC */);
1566
1567 if (TraceGen1Time) accumulated_time()->start();
1568
1569 // Let the size policy know we're starting
1570 size_policy->major_collection_begin();
1571
1572 // When collecting the permanent generation methodOops may be moving,
1573 // so we either have to flush all bcp data or convert it into bci.
1574 CodeCache::gc_prologue();
1575 Threads::gc_prologue();
1576
1577 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1578 COMPILER2_PRESENT(DerivedPointerTable::clear());
1579
1580 ref_processor()->enable_discovery();
1581 ref_processor()->snap_policy(maximum_heap_compaction);
1582
1583 bool marked_for_unloading = false;
1584
1585 marking_start.update();
1586 marking_phase(vmthread_cm, maximum_heap_compaction);
1587
1588 #ifndef PRODUCT
1589 if (TraceParallelOldGCMarkingPhase) {
1590 gclog_or_tty->print_cr("marking_phase: cas_tries %d cas_retries %d "
1591 "cas_by_another %d",
1592 mark_bitmap()->cas_tries(), mark_bitmap()->cas_retries(),
1593 mark_bitmap()->cas_by_another());
1594 }
1595 #endif // #ifndef PRODUCT
1596
1597 bool max_on_system_gc = UseMaximumCompactionOnSystemGC && is_system_gc;
1598 summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
1599
1600 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
1601 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
1602
1603 // adjust_roots() updates Universe::_intArrayKlassObj which is
1604 // needed by the compaction for filling holes in the dense prefix.
1605 adjust_roots();
1606
1607 compaction_start.update();
1608 // Does the perm gen always have to be done serially because
1609 // klasses are used in the update of an object?
1610 compact_perm(vmthread_cm);
1611
1612 if (UseParallelOldGCCompacting) {
1613 compact();
1614 } else {
1615 compact_serial(vmthread_cm);
1616 }
1617
1618 // Reset the mark bitmap, summary data, and do other bookkeeping. Must be
1619 // done before resizing.
1620 post_compact();
1621
1622 // Let the size policy know we're done
1623 size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
1624
1625 if (UseAdaptiveSizePolicy) {
1626 if (PrintAdaptiveSizePolicy) {
1627 gclog_or_tty->print("AdaptiveSizeStart: ");
1628 gclog_or_tty->stamp();
1629 gclog_or_tty->print_cr(" collection: %d ",
1630 heap->total_collections());
1631 if (Verbose) {
1632 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d"
1633 " perm_gen_capacity: %d ",
1634 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),
1635 perm_gen->capacity_in_bytes());
1636 }
1637 }
1638
1639 // Don't check if the size_policy is ready here. Let
1640 // the size_policy check that internally.
1641 if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
1642 ((gc_cause != GCCause::_java_lang_system_gc) ||
1643 UseAdaptiveSizePolicyWithSystemGC)) {
1644 // Calculate optimal free space amounts
1645 assert(young_gen->max_size() >
1646 young_gen->from_space()->capacity_in_bytes() +
1647 young_gen->to_space()->capacity_in_bytes(),
1648 "Sizes of space in young gen are out-of-bounds");
1649 size_t max_eden_size = young_gen->max_size() -
1650 young_gen->from_space()->capacity_in_bytes() -
1651 young_gen->to_space()->capacity_in_bytes();
1652 size_policy->compute_generation_free_space(
1653 young_gen->used_in_bytes(),
1654 young_gen->eden_space()->used_in_bytes(),
1655 old_gen->used_in_bytes(),
1656 perm_gen->used_in_bytes(),
1657 young_gen->eden_space()->capacity_in_bytes(),
1658 old_gen->max_gen_size(),
1659 max_eden_size,
1660 true /* full gc*/,
1661 gc_cause);
1662
1663 heap->resize_old_gen(
1664 size_policy->calculated_old_free_size_in_bytes());
1665
1666 // Don't resize the young generation at an major collection. A
1667 // desired young generation size may have been calculated but
1668 // resizing the young generation complicates the code because the
1669 // resizing of the old generation may have moved the boundary
1670 // between the young generation and the old generation. Let the
1671 // young generation resizing happen at the minor collections.
1672 }
1673 if (PrintAdaptiveSizePolicy) {
1674 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
1675 heap->total_collections());
1676 }
1677 }
1678
1679 if (UsePerfData) {
1680 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
1681 counters->update_counters();
1682 counters->update_old_capacity(old_gen->capacity_in_bytes());
1683 counters->update_young_capacity(young_gen->capacity_in_bytes());
1684 }
1685
1686 heap->resize_all_tlabs();
1687
1688 // We collected the perm gen, so we'll resize it here.
1689 perm_gen->compute_new_size(pre_gc_values.perm_gen_used());
1690
1691 if (TraceGen1Time) accumulated_time()->stop();
1692
1693 if (PrintGC) {
1694 if (PrintGCDetails) {
1695 // No GC timestamp here. This is after GC so it would be confusing.
1696 young_gen->print_used_change(pre_gc_values.young_gen_used());
1697 old_gen->print_used_change(pre_gc_values.old_gen_used());
1698 heap->print_heap_change(pre_gc_values.heap_used());
1699 // Print perm gen last (print_heap_change() excludes the perm gen).
1700 perm_gen->print_used_change(pre_gc_values.perm_gen_used());
1701 } else {
1702 heap->print_heap_change(pre_gc_values.heap_used());
1703 }
1704 }
1705
1706 // Track memory usage and detect low memory
1707 MemoryService::track_memory_usage();
1708 heap->update_counters();
1709
1710 if (PrintGCDetails) {
1711 if (size_policy->print_gc_time_limit_would_be_exceeded()) {
1712 if (size_policy->gc_time_limit_exceeded()) {
1713 gclog_or_tty->print_cr(" GC time is exceeding GCTimeLimit "
1714 "of %d%%", GCTimeLimit);
1715 } else {
1716 gclog_or_tty->print_cr(" GC time would exceed GCTimeLimit "
1717 "of %d%%", GCTimeLimit);
1718 }
1719 }
1720 size_policy->set_print_gc_time_limit_would_be_exceeded(false);
1721 }
1722 }
1723
1724 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1725 HandleMark hm; // Discard invalid handles created during verification
1726 gclog_or_tty->print(" VerifyAfterGC:");
1727 Universe::verify(false);
1728 }
1729
1730 // Re-verify object start arrays
1731 if (VerifyObjectStartArray &&
1732 VerifyAfterGC) {
1733 old_gen->verify_object_start_array();
1734 perm_gen->verify_object_start_array();
1735 }
1736
1737 if (ZapUnusedHeapArea) {
1738 old_gen->object_space()->check_mangled_unused_area_complete();
1739 perm_gen->object_space()->check_mangled_unused_area_complete();
1740 }
1741
1742 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1743
1744 collection_exit.update();
1745
1746 if (PrintHeapAtGC) {
1747 Universe::print_heap_after_gc();
1748 }
1749 if (PrintGCTaskTimeStamps) {
1750 gclog_or_tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " "
1751 INT64_FORMAT,
1752 marking_start.ticks(), compaction_start.ticks(),
1753 collection_exit.ticks());
1754 gc_task_manager()->print_task_time_stamps();
1755 }
1756 }
1757
1758 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
1759 PSYoungGen* young_gen,
1760 PSOldGen* old_gen) {
1761 MutableSpace* const eden_space = young_gen->eden_space();
1762 assert(!eden_space->is_empty(), "eden must be non-empty");
1763 assert(young_gen->virtual_space()->alignment() ==
1764 old_gen->virtual_space()->alignment(), "alignments do not match");
1765
1766 if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
1767 return false;
1768 }
1769
1770 // Both generations must be completely committed.
1771 if (young_gen->virtual_space()->uncommitted_size() != 0) {
1772 return false;
1773 }
1774 if (old_gen->virtual_space()->uncommitted_size() != 0) {
1775 return false;
1776 }
1777
1778 // Figure out how much to take from eden. Include the average amount promoted
1779 // in the total; otherwise the next young gen GC will simply bail out to a
1780 // full GC.
1781 const size_t alignment = old_gen->virtual_space()->alignment();
1782 const size_t eden_used = eden_space->used_in_bytes();
1783 const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
1784 const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
1785 const size_t eden_capacity = eden_space->capacity_in_bytes();
1786
1787 if (absorb_size >= eden_capacity) {
1788 return false; // Must leave some space in eden.
1789 }
1790
1791 const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
1792 if (new_young_size < young_gen->min_gen_size()) {
1793 return false; // Respect young gen minimum size.
1794 }
1795
1796 if (TraceAdaptiveGCBoundary && Verbose) {
1797 gclog_or_tty->print(" absorbing " SIZE_FORMAT "K: "
1798 "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
1799 "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
1800 "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
1801 absorb_size / K,
1802 eden_capacity / K, (eden_capacity - absorb_size) / K,
1803 young_gen->from_space()->used_in_bytes() / K,
1804 young_gen->to_space()->used_in_bytes() / K,
1805 young_gen->capacity_in_bytes() / K, new_young_size / K);
1806 }
1807
1808 // Fill the unused part of the old gen.
1809 MutableSpace* const old_space = old_gen->object_space();
1810 MemRegion old_gen_unused(old_space->top(), old_space->end());
1811 if (!old_gen_unused.is_empty()) {
1812 SharedHeap::fill_region_with_object(old_gen_unused);
1813 }
1814
1815 // Take the live data from eden and set both top and end in the old gen to
1816 // eden top. (Need to set end because reset_after_change() mangles the region
1817 // from end to virtual_space->high() in debug builds).
1818 HeapWord* const new_top = eden_space->top();
1819 old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
1820 absorb_size);
1821 young_gen->reset_after_change();
1822 old_space->set_top(new_top);
1823 old_space->set_end(new_top);
1824 old_gen->reset_after_change();
1825
1826 // Update the object start array for the filler object and the data from eden.
1827 ObjectStartArray* const start_array = old_gen->start_array();
1828 HeapWord* const start = old_gen_unused.start();
1829 for (HeapWord* addr = start; addr < new_top; addr += oop(addr)->size()) {
1830 start_array->allocate_block(addr);
1831 }
1832
1833 // Could update the promoted average here, but it is not typically updated at
1834 // full GCs and the value to use is unclear. Something like
1835 //
1836 // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
1837
1838 size_policy->set_bytes_absorbed_from_eden(absorb_size);
1839 return true;
1840 }
1841
1842 GCTaskManager* const PSParallelCompact::gc_task_manager() {
1843 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
1844 "shouldn't return NULL");
1845 return ParallelScavengeHeap::gc_task_manager();
1846 }
1847
1848 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
1849 bool maximum_heap_compaction) {
1850 // Recursively traverse all live objects and mark them
1851 EventMark m("1 mark object");
1852 TraceTime tm("marking phase", print_phases(), true, gclog_or_tty);
1853
1854 ParallelScavengeHeap* heap = gc_heap();
1855 uint parallel_gc_threads = heap->gc_task_manager()->workers();
1856 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
1857 ParallelTaskTerminator terminator(parallel_gc_threads, qset);
1858
1859 PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
1860 PSParallelCompact::FollowStackClosure follow_stack_closure(cm);
1861
1862 {
1863 TraceTime tm_m("par mark", print_phases(), true, gclog_or_tty);
1864
1865 GCTaskQueue* q = GCTaskQueue::create();
1866
1867 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
1868 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
1869 // We scan the thread roots in parallel
1870 Threads::create_thread_roots_marking_tasks(q);
1871 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
1872 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
1873 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
1874 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
1875 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
1876 q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::vm_symbols));
1877
1878 if (parallel_gc_threads > 1) {
1879 for (uint j = 0; j < parallel_gc_threads; j++) {
1880 q->enqueue(new StealMarkingTask(&terminator));
1881 }
1882 }
1883
1884 WaitForBarrierGCTask* fin = WaitForBarrierGCTask::create();
1885 q->enqueue(fin);
1886
1887 gc_task_manager()->add_list(q);
1888
1889 fin->wait_for();
1890
1891 // We have to release the barrier tasks!
1892 WaitForBarrierGCTask::destroy(fin);
1893 }
1894
1895 // Process reference objects found during marking
1896 {
1897 TraceTime tm_r("reference processing", print_phases(), true, gclog_or_tty);
1898 if (ref_processor()->processing_is_mt()) {
1899 RefProcTaskExecutor task_executor;
1900 ref_processor()->process_discovered_references(
1901 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, &task_executor);
1902 } else {
1903 ref_processor()->process_discovered_references(
1904 is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL);
1905 }
1906 }
1907
1908 TraceTime tm_c("class unloading", print_phases(), true, gclog_or_tty);
1909 // Follow system dictionary roots and unload classes.
1910 bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
1911
1912 // Follow code cache roots.
1913 CodeCache::do_unloading(is_alive_closure(), &mark_and_push_closure,
1914 purged_class);
1915 follow_stack(cm); // Flush marking stack.
1916
1917 // Update subklass/sibling/implementor links of live klasses
1918 // revisit_klass_stack is used in follow_weak_klass_links().
1919 follow_weak_klass_links(cm);
1920
1921 // Visit symbol and interned string tables and delete unmarked oops
1922 SymbolTable::unlink(is_alive_closure());
1923 StringTable::unlink(is_alive_closure());
1924
1925 assert(cm->marking_stack()->size() == 0, "stack should be empty by now");
1926 assert(cm->overflow_stack()->is_empty(), "stack should be empty by now");
1927 }
1928
1929 // This should be moved to the shared markSweep code!
1930 class PSAlwaysTrueClosure: public BoolObjectClosure {
1931 public:
1932 void do_object(oop p) { ShouldNotReachHere(); }
1933 bool do_object_b(oop p) { return true; }
1934 };
1935 static PSAlwaysTrueClosure always_true;
1936
1937 void PSParallelCompact::adjust_roots() {
1938 // Adjust the pointers to reflect the new locations
1939 EventMark m("3 adjust roots");
1940 TraceTime tm("adjust roots", print_phases(), true, gclog_or_tty);
1941
1942 // General strong roots.
1943 Universe::oops_do(adjust_root_pointer_closure());
1944 ReferenceProcessor::oops_do(adjust_root_pointer_closure());
1945 JNIHandles::oops_do(adjust_root_pointer_closure()); // Global (strong) JNI handles
1946 Threads::oops_do(adjust_root_pointer_closure());
1947 ObjectSynchronizer::oops_do(adjust_root_pointer_closure());
1948 FlatProfiler::oops_do(adjust_root_pointer_closure());
1949 Management::oops_do(adjust_root_pointer_closure());
1950 JvmtiExport::oops_do(adjust_root_pointer_closure());
1951 // SO_AllClasses
1952 SystemDictionary::oops_do(adjust_root_pointer_closure());
1953 vmSymbols::oops_do(adjust_root_pointer_closure());
1954
1955 // Now adjust pointers in remaining weak roots. (All of which should
1956 // have been cleared if they pointed to non-surviving objects.)
1957 // Global (weak) JNI handles
1958 JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure());
1959
1960 CodeCache::oops_do(adjust_pointer_closure());
1961 SymbolTable::oops_do(adjust_root_pointer_closure());
1962 StringTable::oops_do(adjust_root_pointer_closure());
1963 ref_processor()->weak_oops_do(adjust_root_pointer_closure());
1964 // Roots were visited so references into the young gen in roots
1965 // may have been scanned. Process them also.
1966 // Should the reference processor have a span that excludes
1967 // young gen objects?
1968 PSScavenge::reference_processor()->weak_oops_do(
1969 adjust_root_pointer_closure());
1970 }
1971
1972 void PSParallelCompact::compact_perm(ParCompactionManager* cm) {
1973 EventMark m("4 compact perm");
1974 TraceTime tm("compact perm gen", print_phases(), true, gclog_or_tty);
1975 // trace("4");
1976
1977 gc_heap()->perm_gen()->start_array()->reset();
1978 move_and_update(cm, perm_space_id);
1979 }
1980
1981 void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q,
1982 uint parallel_gc_threads)
1983 {
1984 TraceTime tm("drain task setup", print_phases(), true, gclog_or_tty);
1985
1986 const unsigned int task_count = MAX2(parallel_gc_threads, 1U);
1987 for (unsigned int j = 0; j < task_count; j++) {
1988 q->enqueue(new DrainStacksCompactionTask());
1989 }
1990
1991 // Find all regions that are available (can be filled immediately) and
1992 // distribute them to the thread stacks. The iteration is done in reverse
1993 // order (high to low) so the regions will be removed in ascending order.
1994
1995 const ParallelCompactData& sd = PSParallelCompact::summary_data();
1996
1997 size_t fillable_regions = 0; // A count for diagnostic purposes.
1998 unsigned int which = 0; // The worker thread number.
1999
2000 for (unsigned int id = to_space_id; id > perm_space_id; --id) {
2001 SpaceInfo* const space_info = _space_info + id;
2002 MutableSpace* const space = space_info->space();
2003 HeapWord* const new_top = space_info->new_top();
2004
2005 const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2006 const size_t end_region =
2007 sd.addr_to_region_idx(sd.region_align_up(new_top));
2008 assert(end_region > 0, "perm gen cannot be empty");
2009
2010 for (size_t cur = end_region - 1; cur >= beg_region; --cur) {
2011 if (sd.region(cur)->claim_unsafe()) {
2012 ParCompactionManager* cm = ParCompactionManager::manager_array(which);
2013 cm->save_for_processing(cur);
2014
2015 if (TraceParallelOldGCCompactionPhase && Verbose) {
2016 const size_t count_mod_8 = fillable_regions & 7;
2017 if (count_mod_8 == 0) gclog_or_tty->print("fillable: ");
2018 gclog_or_tty->print(" " SIZE_FORMAT_W(7), cur);
2019 if (count_mod_8 == 7) gclog_or_tty->cr();
2020 }
2021
2022 NOT_PRODUCT(++fillable_regions;)
2023
2024 // Assign regions to threads in round-robin fashion.
2025 if (++which == task_count) {
2026 which = 0;
2027 }
2028 }
2029 }
2030 }
2031
2032 if (TraceParallelOldGCCompactionPhase) {
2033 if (Verbose && (fillable_regions & 7) != 0) gclog_or_tty->cr();
2034 gclog_or_tty->print_cr("%u initially fillable regions", fillable_regions);
2035 }
2036 }
2037
2038 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2039
2040 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2041 uint parallel_gc_threads) {
2042 TraceTime tm("dense prefix task setup", print_phases(), true, gclog_or_tty);
2043
2044 ParallelCompactData& sd = PSParallelCompact::summary_data();
2045
2046 // Iterate over all the spaces adding tasks for updating
2047 // regions in the dense prefix. Assume that 1 gc thread
2048 // will work on opening the gaps and the remaining gc threads
2049 // will work on the dense prefix.
2050 SpaceId space_id = old_space_id;
2051 while (space_id != last_space_id) {
2052 HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2053 const MutableSpace* const space = _space_info[space_id].space();
2054
2055 if (dense_prefix_end == space->bottom()) {
2056 // There is no dense prefix for this space.
2057 space_id = next_compaction_space_id(space_id);
2058 continue;
2059 }
2060
2061 // The dense prefix is before this region.
2062 size_t region_index_end_dense_prefix =
2063 sd.addr_to_region_idx(dense_prefix_end);
2064 RegionData* const dense_prefix_cp =
2065 sd.region(region_index_end_dense_prefix);
2066 assert(dense_prefix_end == space->end() ||
2067 dense_prefix_cp->available() ||
2068 dense_prefix_cp->claimed(),
2069 "The region after the dense prefix should always be ready to fill");
2070
2071 size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2072
2073 // Is there dense prefix work?
2074 size_t total_dense_prefix_regions =
2075 region_index_end_dense_prefix - region_index_start;
2076 // How many regions of the dense prefix should be given to
2077 // each thread?
2078 if (total_dense_prefix_regions > 0) {
2079 uint tasks_for_dense_prefix = 1;
2080 if (UseParallelDensePrefixUpdate) {
2081 if (total_dense_prefix_regions <=
2082 (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2083 // Don't over partition. This assumes that
2084 // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2085 // so there are not many regions to process.
2086 tasks_for_dense_prefix = parallel_gc_threads;
2087 } else {
2088 // Over partition
2089 tasks_for_dense_prefix = parallel_gc_threads *
2090 PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2091 }
2092 }
2093 size_t regions_per_thread = total_dense_prefix_regions /
2094 tasks_for_dense_prefix;
2095 // Give each thread at least 1 region.
2096 if (regions_per_thread == 0) {
2097 regions_per_thread = 1;
2098 }
2099
2100 for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2101 if (region_index_start >= region_index_end_dense_prefix) {
2102 break;
2103 }
2104 // region_index_end is not processed
2105 size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2106 region_index_end_dense_prefix);
2107 q->enqueue(new UpdateDensePrefixTask(
2108 space_id,
2109 region_index_start,
2110 region_index_end));
2111 region_index_start = region_index_end;
2112 }
2113 }
2114 // This gets any part of the dense prefix that did not
2115 // fit evenly.
2116 if (region_index_start < region_index_end_dense_prefix) {
2117 q->enqueue(new UpdateDensePrefixTask(
2118 space_id,
2119 region_index_start,
2120 region_index_end_dense_prefix));
2121 }
2122 space_id = next_compaction_space_id(space_id);
2123 } // End tasks for dense prefix
2124 }
2125
2126 void PSParallelCompact::enqueue_region_stealing_tasks(
2127 GCTaskQueue* q,
2128 ParallelTaskTerminator* terminator_ptr,
2129 uint parallel_gc_threads) {
2130 TraceTime tm("steal task setup", print_phases(), true, gclog_or_tty);
2131
2132 // Once a thread has drained it's stack, it should try to steal regions from
2133 // other threads.
2134 if (parallel_gc_threads > 1) {
2135 for (uint j = 0; j < parallel_gc_threads; j++) {
2136 q->enqueue(new StealRegionCompactionTask(terminator_ptr));
2137 }
2138 }
2139 }
2140
2141 void PSParallelCompact::compact() {
2142 EventMark m("5 compact");
2143 // trace("5");
2144 TraceTime tm("compaction phase", print_phases(), true, gclog_or_tty);
2145
2146 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
2147 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
2148 PSOldGen* old_gen = heap->old_gen();
2149 old_gen->start_array()->reset();
2150 uint parallel_gc_threads = heap->gc_task_manager()->workers();
2151 TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2152 ParallelTaskTerminator terminator(parallel_gc_threads, qset);
2153
2154 GCTaskQueue* q = GCTaskQueue::create();
2155 enqueue_region_draining_tasks(q, parallel_gc_threads);
2156 enqueue_dense_prefix_tasks(q, parallel_gc_threads);
2157 enqueue_region_stealing_tasks(q, &terminator, parallel_gc_threads);
2158
2159 {
2160 TraceTime tm_pc("par compact", print_phases(), true, gclog_or_tty);
2161
2162 WaitForBarrierGCTask* fin = WaitForBarrierGCTask::create();
2163 q->enqueue(fin);
2164
2165 gc_task_manager()->add_list(q);
2166
2167 fin->wait_for();
2168
2169 // We have to release the barrier tasks!
2170 WaitForBarrierGCTask::destroy(fin);
2171
2172 #ifdef ASSERT
2173 // Verify that all regions have been processed before the deferred updates.
2174 // Note that perm_space_id is skipped; this type of verification is not
2175 // valid until the perm gen is compacted by regions.
2176 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2177 verify_complete(SpaceId(id));
2178 }
2179 #endif
2180 }
2181
2182 {
2183 // Update the deferred objects, if any. Any compaction manager can be used.
2184 TraceTime tm_du("deferred updates", print_phases(), true, gclog_or_tty);
2185 ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2186 for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2187 update_deferred_objects(cm, SpaceId(id));
2188 }
2189 }
2190 }
2191
2192 #ifdef ASSERT
2193 void PSParallelCompact::verify_complete(SpaceId space_id) {
2194 // All Regions between space bottom() to new_top() should be marked as filled
2195 // and all Regions between new_top() and top() should be available (i.e.,
2196 // should have been emptied).
2197 ParallelCompactData& sd = summary_data();
2198 SpaceInfo si = _space_info[space_id];
2199 HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2200 HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2201 const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2202 const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2203 const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2204
2205 bool issued_a_warning = false;
2206
2207 size_t cur_region;
2208 for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2209 const RegionData* const c = sd.region(cur_region);
2210 if (!c->completed()) {
2211 warning("region " SIZE_FORMAT " not filled: "
2212 "destination_count=" SIZE_FORMAT,
2213 cur_region, c->destination_count());
2214 issued_a_warning = true;
2215 }
2216 }
2217
2218 for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2219 const RegionData* const c = sd.region(cur_region);
2220 if (!c->available()) {
2221 warning("region " SIZE_FORMAT " not empty: "
2222 "destination_count=" SIZE_FORMAT,
2223 cur_region, c->destination_count());
2224 issued_a_warning = true;
2225 }
2226 }
2227
2228 if (issued_a_warning) {
2229 print_region_ranges();
2230 }
2231 }
2232 #endif // #ifdef ASSERT
2233
2234 void PSParallelCompact::compact_serial(ParCompactionManager* cm) {
2235 EventMark m("5 compact serial");
2236 TraceTime tm("compact serial", print_phases(), true, gclog_or_tty);
2237
2238 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
2239 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
2240
2241 PSYoungGen* young_gen = heap->young_gen();
2242 PSOldGen* old_gen = heap->old_gen();
2243
2244 old_gen->start_array()->reset();
2245 old_gen->move_and_update(cm);
2246 young_gen->move_and_update(cm);
2247 }
2248
2249
2250 void PSParallelCompact::follow_stack(ParCompactionManager* cm) {
2251 while(!cm->overflow_stack()->is_empty()) {
2252 oop obj = cm->overflow_stack()->pop();
2253 obj->follow_contents(cm);
2254 }
2255
2256 oop obj;
2257 // obj is a reference!!!
2258 while (cm->marking_stack()->pop_local(obj)) {
2259 // It would be nice to assert about the type of objects we might
2260 // pop, but they can come from anywhere, unfortunately.
2261 obj->follow_contents(cm);
2262 }
2263 }
2264
2265 void
2266 PSParallelCompact::follow_weak_klass_links(ParCompactionManager* serial_cm) {
2267 // All klasses on the revisit stack are marked at this point.
2268 // Update and follow all subklass, sibling and implementor links.
2269 for (uint i = 0; i < ParallelGCThreads+1; i++) {
2270 ParCompactionManager* cm = ParCompactionManager::manager_array(i);
2271 KeepAliveClosure keep_alive_closure(cm);
2272 for (int i = 0; i < cm->revisit_klass_stack()->length(); i++) {
2273 cm->revisit_klass_stack()->at(i)->follow_weak_klass_links(
2274 is_alive_closure(),
2275 &keep_alive_closure);
2276 }
2277 follow_stack(cm);
2278 }
2279 }
2280
2281 void
2282 PSParallelCompact::revisit_weak_klass_link(ParCompactionManager* cm, Klass* k) {
2283 cm->revisit_klass_stack()->push(k);
2284 }
2285
2286 #ifdef VALIDATE_MARK_SWEEP
2287
2288 void PSParallelCompact::track_adjusted_pointer(void* p, bool isroot) {
2289 if (!ValidateMarkSweep)
2290 return;
2291
2292 if (!isroot) {
2293 if (_pointer_tracking) {
2294 guarantee(_adjusted_pointers->contains(p), "should have seen this pointer");
2295 _adjusted_pointers->remove(p);
2296 }
2297 } else {
2298 ptrdiff_t index = _root_refs_stack->find(p);
2299 if (index != -1) {
2300 int l = _root_refs_stack->length();
2301 if (l > 0 && l - 1 != index) {
2302 void* last = _root_refs_stack->pop();
2303 assert(last != p, "should be different");
2304 _root_refs_stack->at_put(index, last);
2305 } else {
2306 _root_refs_stack->remove(p);
2307 }
2308 }
2309 }
2310 }
2311
2312
2313 void PSParallelCompact::check_adjust_pointer(void* p) {
2314 _adjusted_pointers->push(p);
2315 }
2316
2317
2318 class AdjusterTracker: public OopClosure {
2319 public:
2320 AdjusterTracker() {};
2321 void do_oop(oop* o) { PSParallelCompact::check_adjust_pointer(o); }
2322 void do_oop(narrowOop* o) { PSParallelCompact::check_adjust_pointer(o); }
2323 };
2324
2325
2326 void PSParallelCompact::track_interior_pointers(oop obj) {
2327 if (ValidateMarkSweep) {
2328 _adjusted_pointers->clear();
2329 _pointer_tracking = true;
2330
2331 AdjusterTracker checker;
2332 obj->oop_iterate(&checker);
2333 }
2334 }
2335
2336
2337 void PSParallelCompact::check_interior_pointers() {
2338 if (ValidateMarkSweep) {
2339 _pointer_tracking = false;
2340 guarantee(_adjusted_pointers->length() == 0, "should have processed the same pointers");
2341 }
2342 }
2343
2344
2345 void PSParallelCompact::reset_live_oop_tracking(bool at_perm) {
2346 if (ValidateMarkSweep) {
2347 guarantee((size_t)_live_oops->length() == _live_oops_index, "should be at end of live oops");
2348 _live_oops_index = at_perm ? _live_oops_index_at_perm : 0;
2349 }
2350 }
2351
2352
2353 void PSParallelCompact::register_live_oop(oop p, size_t size) {
2354 if (ValidateMarkSweep) {
2355 _live_oops->push(p);
2356 _live_oops_size->push(size);
2357 _live_oops_index++;
2358 }
2359 }
2360
2361 void PSParallelCompact::validate_live_oop(oop p, size_t size) {
2362 if (ValidateMarkSweep) {
2363 oop obj = _live_oops->at((int)_live_oops_index);
2364 guarantee(obj == p, "should be the same object");
2365 guarantee(_live_oops_size->at((int)_live_oops_index) == size, "should be the same size");
2366 _live_oops_index++;
2367 }
2368 }
2369
2370 void PSParallelCompact::live_oop_moved_to(HeapWord* q, size_t size,
2371 HeapWord* compaction_top) {
2372 assert(oop(q)->forwardee() == NULL || oop(q)->forwardee() == oop(compaction_top),
2373 "should be moved to forwarded location");
2374 if (ValidateMarkSweep) {
2375 PSParallelCompact::validate_live_oop(oop(q), size);
2376 _live_oops_moved_to->push(oop(compaction_top));
2377 }
2378 if (RecordMarkSweepCompaction) {
2379 _cur_gc_live_oops->push(q);
2380 _cur_gc_live_oops_moved_to->push(compaction_top);
2381 _cur_gc_live_oops_size->push(size);
2382 }
2383 }
2384
2385
2386 void PSParallelCompact::compaction_complete() {
2387 if (RecordMarkSweepCompaction) {
2388 GrowableArray<HeapWord*>* _tmp_live_oops = _cur_gc_live_oops;
2389 GrowableArray<HeapWord*>* _tmp_live_oops_moved_to = _cur_gc_live_oops_moved_to;
2390 GrowableArray<size_t> * _tmp_live_oops_size = _cur_gc_live_oops_size;
2391
2392 _cur_gc_live_oops = _last_gc_live_oops;
2393 _cur_gc_live_oops_moved_to = _last_gc_live_oops_moved_to;
2394 _cur_gc_live_oops_size = _last_gc_live_oops_size;
2395 _last_gc_live_oops = _tmp_live_oops;
2396 _last_gc_live_oops_moved_to = _tmp_live_oops_moved_to;
2397 _last_gc_live_oops_size = _tmp_live_oops_size;
2398 }
2399 }
2400
2401
2402 void PSParallelCompact::print_new_location_of_heap_address(HeapWord* q) {
2403 if (!RecordMarkSweepCompaction) {
2404 tty->print_cr("Requires RecordMarkSweepCompaction to be enabled");
2405 return;
2406 }
2407
2408 if (_last_gc_live_oops == NULL) {
2409 tty->print_cr("No compaction information gathered yet");
2410 return;
2411 }
2412
2413 for (int i = 0; i < _last_gc_live_oops->length(); i++) {
2414 HeapWord* old_oop = _last_gc_live_oops->at(i);
2415 size_t sz = _last_gc_live_oops_size->at(i);
2416 if (old_oop <= q && q < (old_oop + sz)) {
2417 HeapWord* new_oop = _last_gc_live_oops_moved_to->at(i);
2418 size_t offset = (q - old_oop);
2419 tty->print_cr("Address " PTR_FORMAT, q);
2420 tty->print_cr(" Was in oop " PTR_FORMAT ", size %d, at offset %d", old_oop, sz, offset);
2421 tty->print_cr(" Now in oop " PTR_FORMAT ", actual address " PTR_FORMAT, new_oop, new_oop + offset);
2422 return;
2423 }
2424 }
2425
2426 tty->print_cr("Address " PTR_FORMAT " not found in live oop information from last GC", q);
2427 }
2428 #endif //VALIDATE_MARK_SWEEP
2429
2430 // Update interior oops in the ranges of regions [beg_region, end_region).
2431 void
2432 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2433 SpaceId space_id,
2434 size_t beg_region,
2435 size_t end_region) {
2436 ParallelCompactData& sd = summary_data();
2437 ParMarkBitMap* const mbm = mark_bitmap();
2438
2439 HeapWord* beg_addr = sd.region_to_addr(beg_region);
2440 HeapWord* const end_addr = sd.region_to_addr(end_region);
2441 assert(beg_region <= end_region, "bad region range");
2442 assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2443
2444 #ifdef ASSERT
2445 // Claim the regions to avoid triggering an assert when they are marked as
2446 // filled.
2447 for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2448 assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2449 }
2450 #endif // #ifdef ASSERT
2451
2452 if (beg_addr != space(space_id)->bottom()) {
2453 // Find the first live object or block of dead space that *starts* in this
2454 // range of regions. If a partial object crosses onto the region, skip it;
2455 // it will be marked for 'deferred update' when the object head is
2456 // processed. If dead space crosses onto the region, it is also skipped; it
2457 // will be filled when the prior region is processed. If neither of those
2458 // apply, the first word in the region is the start of a live object or dead
2459 // space.
2460 assert(beg_addr > space(space_id)->bottom(), "sanity");
2461 const RegionData* const cp = sd.region(beg_region);
2462 if (cp->partial_obj_size() != 0) {
2463 beg_addr = sd.partial_obj_end(beg_region);
2464 } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2465 beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2466 }
2467 }
2468
2469 if (beg_addr < end_addr) {
2470 // A live object or block of dead space starts in this range of Regions.
2471 HeapWord* const dense_prefix_end = dense_prefix(space_id);
2472
2473 // Create closures and iterate.
2474 UpdateOnlyClosure update_closure(mbm, cm, space_id);
2475 FillClosure fill_closure(cm, space_id);
2476 ParMarkBitMap::IterationStatus status;
2477 status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2478 dense_prefix_end);
2479 if (status == ParMarkBitMap::incomplete) {
2480 update_closure.do_addr(update_closure.source());
2481 }
2482 }
2483
2484 // Mark the regions as filled.
2485 RegionData* const beg_cp = sd.region(beg_region);
2486 RegionData* const end_cp = sd.region(end_region);
2487 for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2488 cp->set_completed();
2489 }
2490 }
2491
2492 // Return the SpaceId for the space containing addr. If addr is not in the
2493 // heap, last_space_id is returned. In debug mode it expects the address to be
2494 // in the heap and asserts such.
2495 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2496 assert(Universe::heap()->is_in_reserved(addr), "addr not in the heap");
2497
2498 for (unsigned int id = perm_space_id; id < last_space_id; ++id) {
2499 if (_space_info[id].space()->contains(addr)) {
2500 return SpaceId(id);
2501 }
2502 }
2503
2504 assert(false, "no space contains the addr");
2505 return last_space_id;
2506 }
2507
2508 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2509 SpaceId id) {
2510 assert(id < last_space_id, "bad space id");
2511
2512 ParallelCompactData& sd = summary_data();
2513 const SpaceInfo* const space_info = _space_info + id;
2514 ObjectStartArray* const start_array = space_info->start_array();
2515
2516 const MutableSpace* const space = space_info->space();
2517 assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2518 HeapWord* const beg_addr = space_info->dense_prefix();
2519 HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2520
2521 const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2522 const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2523 const RegionData* cur_region;
2524 for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2525 HeapWord* const addr = cur_region->deferred_obj_addr();
2526 if (addr != NULL) {
2527 if (start_array != NULL) {
2528 start_array->allocate_block(addr);
2529 }
2530 oop(addr)->update_contents(cm);
2531 assert(oop(addr)->is_oop_or_null(), "should be an oop now");
2532 }
2533 }
2534 }
2535
2536 // Skip over count live words starting from beg, and return the address of the
2537 // next live word. Unless marked, the word corresponding to beg is assumed to
2538 // be dead. Callers must either ensure beg does not correspond to the middle of
2539 // an object, or account for those live words in some other way. Callers must
2540 // also ensure that there are enough live words in the range [beg, end) to skip.
2541 HeapWord*
2542 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2543 {
2544 assert(count > 0, "sanity");
2545
2546 ParMarkBitMap* m = mark_bitmap();
2547 idx_t bits_to_skip = m->words_to_bits(count);
2548 idx_t cur_beg = m->addr_to_bit(beg);
2549 const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
2550
2551 do {
2552 cur_beg = m->find_obj_beg(cur_beg, search_end);
2553 idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2554 const size_t obj_bits = cur_end - cur_beg + 1;
2555 if (obj_bits > bits_to_skip) {
2556 return m->bit_to_addr(cur_beg + bits_to_skip);
2557 }
2558 bits_to_skip -= obj_bits;
2559 cur_beg = cur_end + 1;
2560 } while (bits_to_skip > 0);
2561
2562 // Skipping the desired number of words landed just past the end of an object.
2563 // Find the start of the next object.
2564 cur_beg = m->find_obj_beg(cur_beg, search_end);
2565 assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2566 return m->bit_to_addr(cur_beg);
2567 }
2568
2569 HeapWord*
2570 PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2571 size_t src_region_idx)
2572 {
2573 ParMarkBitMap* const bitmap = mark_bitmap();
2574 const ParallelCompactData& sd = summary_data();
2575 const size_t RegionSize = ParallelCompactData::RegionSize;
2576
2577 assert(sd.is_region_aligned(dest_addr), "not aligned");
2578
2579 const RegionData* const src_region_ptr = sd.region(src_region_idx);
2580 const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2581 HeapWord* const src_region_destination = src_region_ptr->destination();
2582
2583 assert(dest_addr >= src_region_destination, "wrong src region");
2584 assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2585
2586 HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2587 HeapWord* const src_region_end = src_region_beg + RegionSize;
2588
2589 HeapWord* addr = src_region_beg;
2590 if (dest_addr == src_region_destination) {
2591 // Return the first live word in the source region.
2592 if (partial_obj_size == 0) {
2593 addr = bitmap->find_obj_beg(addr, src_region_end);
2594 assert(addr < src_region_end, "no objects start in src region");
2595 }
2596 return addr;
2597 }
2598
2599 // Must skip some live data.
2600 size_t words_to_skip = dest_addr - src_region_destination;
2601 assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2602
2603 if (partial_obj_size >= words_to_skip) {
2604 // All the live words to skip are part of the partial object.
2605 addr += words_to_skip;
2606 if (partial_obj_size == words_to_skip) {
2607 // Find the first live word past the partial object.
2608 addr = bitmap->find_obj_beg(addr, src_region_end);
2609 assert(addr < src_region_end, "wrong src region");
2610 }
2611 return addr;
2612 }
2613
2614 // Skip over the partial object (if any).
2615 if (partial_obj_size != 0) {
2616 words_to_skip -= partial_obj_size;
2617 addr += partial_obj_size;
2618 }
2619
2620 // Skip over live words due to objects that start in the region.
2621 addr = skip_live_words(addr, src_region_end, words_to_skip);
2622 assert(addr < src_region_end, "wrong src region");
2623 return addr;
2624 }
2625
2626 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2627 size_t beg_region,
2628 HeapWord* end_addr)
2629 {
2630 ParallelCompactData& sd = summary_data();
2631 RegionData* const beg = sd.region(beg_region);
2632 HeapWord* const end_addr_aligned_up = sd.region_align_up(end_addr);
2633 RegionData* const end = sd.addr_to_region_ptr(end_addr_aligned_up);
2634 size_t cur_idx = beg_region;
2635 for (RegionData* cur = beg; cur < end; ++cur, ++cur_idx) {
2636 assert(cur->data_size() > 0, "region must have live data");
2637 cur->decrement_destination_count();
2638 if (cur_idx <= cur->source_region() && cur->available() && cur->claim()) {
2639 cm->save_for_processing(cur_idx);
2640 }
2641 }
2642 }
2643
2644 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2645 SpaceId& src_space_id,
2646 HeapWord*& src_space_top,
2647 HeapWord* end_addr)
2648 {
2649 typedef ParallelCompactData::RegionData RegionData;
2650
2651 ParallelCompactData& sd = PSParallelCompact::summary_data();
2652 const size_t region_size = ParallelCompactData::RegionSize;
2653
2654 size_t src_region_idx = 0;
2655
2656 // Skip empty regions (if any) up to the top of the space.
2657 HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2658 RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2659 HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2660 const RegionData* const top_region_ptr =
2661 sd.addr_to_region_ptr(top_aligned_up);
2662 while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2663 ++src_region_ptr;
2664 }
2665
2666 if (src_region_ptr < top_region_ptr) {
2667 // The next source region is in the current space. Update src_region_idx
2668 // and the source address to match src_region_ptr.
2669 src_region_idx = sd.region(src_region_ptr);
2670 HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
2671 if (src_region_addr > closure.source()) {
2672 closure.set_source(src_region_addr);
2673 }
2674 return src_region_idx;
2675 }
2676
2677 // Switch to a new source space and find the first non-empty region.
2678 unsigned int space_id = src_space_id + 1;
2679 assert(space_id < last_space_id, "not enough spaces");
2680
2681 HeapWord* const destination = closure.destination();
2682
2683 do {
2684 MutableSpace* space = _space_info[space_id].space();
2685 HeapWord* const bottom = space->bottom();
2686 const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
2687
2688 // Iterate over the spaces that do not compact into themselves.
2689 if (bottom_cp->destination() != bottom) {
2690 HeapWord* const top_aligned_up = sd.region_align_up(space->top());
2691 const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
2692
2693 for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
2694 if (src_cp->live_obj_size() > 0) {
2695 // Found it.
2696 assert(src_cp->destination() == destination,
2697 "first live obj in the space must match the destination");
2698 assert(src_cp->partial_obj_size() == 0,
2699 "a space cannot begin with a partial obj");
2700
2701 src_space_id = SpaceId(space_id);
2702 src_space_top = space->top();
2703 const size_t src_region_idx = sd.region(src_cp);
2704 closure.set_source(sd.region_to_addr(src_region_idx));
2705 return src_region_idx;
2706 } else {
2707 assert(src_cp->data_size() == 0, "sanity");
2708 }
2709 }
2710 }
2711 } while (++space_id < last_space_id);
2712
2713 assert(false, "no source region was found");
2714 return 0;
2715 }
2716
2717 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
2718 {
2719 typedef ParMarkBitMap::IterationStatus IterationStatus;
2720 const size_t RegionSize = ParallelCompactData::RegionSize;
2721 ParMarkBitMap* const bitmap = mark_bitmap();
2722 ParallelCompactData& sd = summary_data();
2723 RegionData* const region_ptr = sd.region(region_idx);
2724
2725 // Get the items needed to construct the closure.
2726 HeapWord* dest_addr = sd.region_to_addr(region_idx);
2727 SpaceId dest_space_id = space_id(dest_addr);
2728 ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
2729 HeapWord* new_top = _space_info[dest_space_id].new_top();
2730 assert(dest_addr < new_top, "sanity");
2731 const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
2732
2733 // Get the source region and related info.
2734 size_t src_region_idx = region_ptr->source_region();
2735 SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2736 HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2737
2738 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
2739 closure.set_source(first_src_addr(dest_addr, src_region_idx));
2740
2741 // Adjust src_region_idx to prepare for decrementing destination counts (the
2742 // destination count is not decremented when a region is copied to itself).
2743 if (src_region_idx == region_idx) {
2744 src_region_idx += 1;
2745 }
2746
2747 if (bitmap->is_unmarked(closure.source())) {
2748 // The first source word is in the middle of an object; copy the remainder
2749 // of the object or as much as will fit. The fact that pointer updates were
2750 // deferred will be noted when the object header is processed.
2751 HeapWord* const old_src_addr = closure.source();
2752 closure.copy_partial_obj();
2753 if (closure.is_full()) {
2754 decrement_destination_counts(cm, src_region_idx, closure.source());
2755 region_ptr->set_deferred_obj_addr(NULL);
2756 region_ptr->set_completed();
2757 return;
2758 }
2759
2760 HeapWord* const end_addr = sd.region_align_down(closure.source());
2761 if (sd.region_align_down(old_src_addr) != end_addr) {
2762 // The partial object was copied from more than one source region.
2763 decrement_destination_counts(cm, src_region_idx, end_addr);
2764
2765 // Move to the next source region, possibly switching spaces as well. All
2766 // args except end_addr may be modified.
2767 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2768 end_addr);
2769 }
2770 }
2771
2772 do {
2773 HeapWord* const cur_addr = closure.source();
2774 HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2775 src_space_top);
2776 IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
2777
2778 if (status == ParMarkBitMap::incomplete) {
2779 // The last obj that starts in the source region does not end in the
2780 // region.
2781 assert(closure.source() < end_addr, "sanity")
2782 HeapWord* const obj_beg = closure.source();
2783 HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
2784 src_space_top);
2785 HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
2786 if (obj_end < range_end) {
2787 // The end was found; the entire object will fit.
2788 status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
2789 assert(status != ParMarkBitMap::would_overflow, "sanity");
2790 } else {
2791 // The end was not found; the object will not fit.
2792 assert(range_end < src_space_top, "obj cannot cross space boundary");
2793 status = ParMarkBitMap::would_overflow;
2794 }
2795 }
2796
2797 if (status == ParMarkBitMap::would_overflow) {
2798 // The last object did not fit. Note that interior oop updates were
2799 // deferred, then copy enough of the object to fill the region.
2800 region_ptr->set_deferred_obj_addr(closure.destination());
2801 status = closure.copy_until_full(); // copies from closure.source()
2802
2803 decrement_destination_counts(cm, src_region_idx, closure.source());
2804 region_ptr->set_completed();
2805 return;
2806 }
2807
2808 if (status == ParMarkBitMap::full) {
2809 decrement_destination_counts(cm, src_region_idx, closure.source());
2810 region_ptr->set_deferred_obj_addr(NULL);
2811 region_ptr->set_completed();
2812 return;
2813 }
2814
2815 decrement_destination_counts(cm, src_region_idx, end_addr);
2816
2817 // Move to the next source region, possibly switching spaces as well. All
2818 // args except end_addr may be modified.
2819 src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2820 end_addr);
2821 } while (true);
2822 }
2823
2824 void
2825 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
2826 const MutableSpace* sp = space(space_id);
2827 if (sp->is_empty()) {
2828 return;
2829 }
2830
2831 ParallelCompactData& sd = PSParallelCompact::summary_data();
2832 ParMarkBitMap* const bitmap = mark_bitmap();
2833 HeapWord* const dp_addr = dense_prefix(space_id);
2834 HeapWord* beg_addr = sp->bottom();
2835 HeapWord* end_addr = sp->top();
2836
2837 #ifdef ASSERT
2838 assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
2839 if (cm->should_verify_only()) {
2840 VerifyUpdateClosure verify_update(cm, sp);
2841 bitmap->iterate(&verify_update, beg_addr, end_addr);
2842 return;
2843 }
2844
2845 if (cm->should_reset_only()) {
2846 ResetObjectsClosure reset_objects(cm);
2847 bitmap->iterate(&reset_objects, beg_addr, end_addr);
2848 return;
2849 }
2850 #endif
2851
2852 const size_t beg_region = sd.addr_to_region_idx(beg_addr);
2853 const size_t dp_region = sd.addr_to_region_idx(dp_addr);
2854 if (beg_region < dp_region) {
2855 update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
2856 }
2857
2858 // The destination of the first live object that starts in the region is one
2859 // past the end of the partial object entering the region (if any).
2860 HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
2861 HeapWord* const new_top = _space_info[space_id].new_top();
2862 assert(new_top >= dest_addr, "bad new_top value");
2863 const size_t words = pointer_delta(new_top, dest_addr);
2864
2865 if (words > 0) {
2866 ObjectStartArray* start_array = _space_info[space_id].start_array();
2867 MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
2868
2869 ParMarkBitMap::IterationStatus status;
2870 status = bitmap->iterate(&closure, dest_addr, end_addr);
2871 assert(status == ParMarkBitMap::full, "iteration not complete");
2872 assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
2873 "live objects skipped because closure is full");
2874 }
2875 }
2876
2877 jlong PSParallelCompact::millis_since_last_gc() {
2878 jlong ret_val = os::javaTimeMillis() - _time_of_last_gc;
2879 // XXX See note in genCollectedHeap::millis_since_last_gc().
2880 if (ret_val < 0) {
2881 NOT_PRODUCT(warning("time warp: %d", ret_val);)
2882 return 0;
2883 }
2884 return ret_val;
2885 }
2886
2887 void PSParallelCompact::reset_millis_since_last_gc() {
2888 _time_of_last_gc = os::javaTimeMillis();
2889 }
2890
2891 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
2892 {
2893 if (source() != destination()) {
2894 assert(source() > destination(), "must copy to the left");
2895 Copy::aligned_conjoint_words(source(), destination(), words_remaining());
2896 }
2897 update_state(words_remaining());
2898 assert(is_full(), "sanity");
2899 return ParMarkBitMap::full;
2900 }
2901
2902 void MoveAndUpdateClosure::copy_partial_obj()
2903 {
2904 size_t words = words_remaining();
2905
2906 HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
2907 HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
2908 if (end_addr < range_end) {
2909 words = bitmap()->obj_size(source(), end_addr);
2910 }
2911
2912 // This test is necessary; if omitted, the pointer updates to a partial object
2913 // that crosses the dense prefix boundary could be overwritten.
2914 if (source() != destination()) {
2915 assert(source() > destination(), "must copy to the left");
2916 Copy::aligned_conjoint_words(source(), destination(), words);
2917 }
2918 update_state(words);
2919 }
2920
2921 ParMarkBitMapClosure::IterationStatus
2922 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
2923 assert(destination() != NULL, "sanity");
2924 assert(bitmap()->obj_size(addr) == words, "bad size");
2925
2926 _source = addr;
2927 assert(PSParallelCompact::summary_data().calc_new_pointer(source()) ==
2928 destination(), "wrong destination");
2929
2930 if (words > words_remaining()) {
2931 return ParMarkBitMap::would_overflow;
2932 }
2933
2934 // The start_array must be updated even if the object is not moving.
2935 if (_start_array != NULL) {
2936 _start_array->allocate_block(destination());
2937 }
2938
2939 if (destination() != source()) {
2940 assert(destination() < source(), "must copy to the left");
2941 Copy::aligned_conjoint_words(source(), destination(), words);
2942 }
2943
2944 oop moved_oop = (oop) destination();
2945 moved_oop->update_contents(compaction_manager());
2946 assert(moved_oop->is_oop_or_null(), "Object should be whole at this point");
2947
2948 update_state(words);
2949 assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
2950 return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
2951 }
2952
2953 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
2954 ParCompactionManager* cm,
2955 PSParallelCompact::SpaceId space_id) :
2956 ParMarkBitMapClosure(mbm, cm),
2957 _space_id(space_id),
2958 _start_array(PSParallelCompact::start_array(space_id))
2959 {
2960 }
2961
2962 // Updates the references in the object to their new values.
2963 ParMarkBitMapClosure::IterationStatus
2964 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
2965 do_addr(addr);
2966 return ParMarkBitMap::incomplete;
2967 }
2968
2969 // Verify the new location using the forwarding pointer
2970 // from MarkSweep::mark_sweep_phase2(). Set the mark_word
2971 // to the initial value.
2972 ParMarkBitMapClosure::IterationStatus
2973 PSParallelCompact::VerifyUpdateClosure::do_addr(HeapWord* addr, size_t words) {
2974 // The second arg (words) is not used.
2975 oop obj = (oop) addr;
2976 HeapWord* forwarding_ptr = (HeapWord*) obj->mark()->decode_pointer();
2977 HeapWord* new_pointer = summary_data().calc_new_pointer(obj);
2978 if (forwarding_ptr == NULL) {
2979 // The object is dead or not moving.
2980 assert(bitmap()->is_unmarked(obj) || (new_pointer == (HeapWord*) obj),
2981 "Object liveness is wrong.");
2982 return ParMarkBitMap::incomplete;
2983 }
2984 assert(UseParallelOldGCDensePrefix ||
2985 (HeapMaximumCompactionInterval > 1) ||
2986 (MarkSweepAlwaysCompactCount > 1) ||
2987 (forwarding_ptr == new_pointer),
2988 "Calculation of new location is incorrect");
2989 return ParMarkBitMap::incomplete;
2990 }
2991
2992 // Reset objects modified for debug checking.
2993 ParMarkBitMapClosure::IterationStatus
2994 PSParallelCompact::ResetObjectsClosure::do_addr(HeapWord* addr, size_t words) {
2995 // The second arg (words) is not used.
2996 oop obj = (oop) addr;
2997 obj->init_mark();
2998 return ParMarkBitMap::incomplete;
2999 }
3000
3001 // Prepare for compaction. This method is executed once
3002 // (i.e., by a single thread) before compaction.
3003 // Save the updated location of the intArrayKlassObj for
3004 // filling holes in the dense prefix.
3005 void PSParallelCompact::compact_prologue() {
3006 _updated_int_array_klass_obj = (klassOop)
3007 summary_data().calc_new_pointer(Universe::intArrayKlassObj());
3008 }
3009
3010 // The initial implementation of this method created a field
3011 // _next_compaction_space_id in SpaceInfo and initialized
3012 // that field in SpaceInfo::initialize_space_info(). That
3013 // required that _next_compaction_space_id be declared a
3014 // SpaceId in SpaceInfo and that would have required that
3015 // either SpaceId be declared in a separate class or that
3016 // it be declared in SpaceInfo. It didn't seem consistent
3017 // to declare it in SpaceInfo (didn't really fit logically).
3018 // Alternatively, defining a separate class to define SpaceId
3019 // seem excessive. This implementation is simple and localizes
3020 // the knowledge.
3021
3022 PSParallelCompact::SpaceId
3023 PSParallelCompact::next_compaction_space_id(SpaceId id) {
3024 assert(id < last_space_id, "id out of range");
3025 switch (id) {
3026 case perm_space_id :
3027 return last_space_id;
3028 case old_space_id :
3029 return eden_space_id;
3030 case eden_space_id :
3031 return from_space_id;
3032 case from_space_id :
3033 return to_space_id;
3034 case to_space_id :
3035 return last_space_id;
3036 default:
3037 assert(false, "Bad space id");
3038 return last_space_id;
3039 }
3040 }