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annotate src/share/vm/gc_implementation/parallelScavenge/psMarkSweepDecorator.cpp @ 3710:4e037604f6ee
use alignment for constants specified in DataPatch.alignment
author | Christian Wimmer <christian.wimmer@oracle.com> |
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date | Mon, 05 Dec 2011 18:15:25 -0800 |
parents | f95d63e2154a |
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0 | 1 /* |
1972 | 2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved. |
0 | 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 * | |
1552
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #include "precompiled.hpp" |
26 #include "classfile/systemDictionary.hpp" | |
27 #include "gc_implementation/parallelScavenge/objectStartArray.hpp" | |
28 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp" | |
29 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp" | |
30 #include "gc_implementation/parallelScavenge/psMarkSweepDecorator.hpp" | |
31 #include "gc_implementation/shared/liveRange.hpp" | |
32 #include "gc_implementation/shared/markSweep.inline.hpp" | |
33 #include "gc_implementation/shared/spaceDecorator.hpp" | |
34 #include "oops/oop.inline.hpp" | |
0 | 35 |
36 PSMarkSweepDecorator* PSMarkSweepDecorator::_destination_decorator = NULL; | |
37 | |
38 | |
39 void PSMarkSweepDecorator::set_destination_decorator_tenured() { | |
40 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
41 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
42 | |
43 _destination_decorator = heap->old_gen()->object_mark_sweep(); | |
44 } | |
45 | |
46 void PSMarkSweepDecorator::set_destination_decorator_perm_gen() { | |
47 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
48 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
49 | |
50 _destination_decorator = heap->perm_gen()->object_mark_sweep(); | |
51 } | |
52 | |
53 void PSMarkSweepDecorator::advance_destination_decorator() { | |
54 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
55 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
56 | |
57 assert(_destination_decorator != NULL, "Sanity"); | |
58 guarantee(_destination_decorator != heap->perm_gen()->object_mark_sweep(), "Cannot advance perm gen decorator"); | |
59 | |
60 PSMarkSweepDecorator* first = heap->old_gen()->object_mark_sweep(); | |
61 PSMarkSweepDecorator* second = heap->young_gen()->eden_mark_sweep(); | |
62 PSMarkSweepDecorator* third = heap->young_gen()->from_mark_sweep(); | |
63 PSMarkSweepDecorator* fourth = heap->young_gen()->to_mark_sweep(); | |
64 | |
65 if ( _destination_decorator == first ) { | |
66 _destination_decorator = second; | |
67 } else if ( _destination_decorator == second ) { | |
68 _destination_decorator = third; | |
69 } else if ( _destination_decorator == third ) { | |
70 _destination_decorator = fourth; | |
71 } else { | |
72 fatal("PSMarkSweep attempting to advance past last compaction area"); | |
73 } | |
74 } | |
75 | |
76 PSMarkSweepDecorator* PSMarkSweepDecorator::destination_decorator() { | |
77 assert(_destination_decorator != NULL, "Sanity"); | |
78 | |
79 return _destination_decorator; | |
80 } | |
81 | |
82 // FIX ME FIX ME FIX ME FIX ME!!!!!!!!! | |
83 // The object forwarding code is duplicated. Factor this out!!!!! | |
84 // | |
85 // This method "precompacts" objects inside its space to dest. It places forwarding | |
86 // pointers into markOops for use by adjust_pointers. If "dest" should overflow, we | |
87 // finish by compacting into our own space. | |
88 | |
89 void PSMarkSweepDecorator::precompact() { | |
90 // Reset our own compact top. | |
91 set_compaction_top(space()->bottom()); | |
92 | |
93 /* We allow some amount of garbage towards the bottom of the space, so | |
94 * we don't start compacting before there is a significant gain to be made. | |
95 * Occasionally, we want to ensure a full compaction, which is determined | |
96 * by the MarkSweepAlwaysCompactCount parameter. This is a significant | |
97 * performance improvement! | |
98 */ | |
99 bool skip_dead = ((PSMarkSweep::total_invocations() % MarkSweepAlwaysCompactCount) != 0); | |
100 | |
438 | 101 size_t allowed_deadspace = 0; |
0 | 102 if (skip_dead) { |
438 | 103 const size_t ratio = allowed_dead_ratio(); |
104 allowed_deadspace = space()->capacity_in_words() * ratio / 100; | |
0 | 105 } |
106 | |
107 // Fetch the current destination decorator | |
108 PSMarkSweepDecorator* dest = destination_decorator(); | |
109 ObjectStartArray* start_array = dest->start_array(); | |
110 | |
111 HeapWord* compact_top = dest->compaction_top(); | |
112 HeapWord* compact_end = dest->space()->end(); | |
113 | |
114 HeapWord* q = space()->bottom(); | |
115 HeapWord* t = space()->top(); | |
116 | |
117 HeapWord* end_of_live= q; /* One byte beyond the last byte of the last | |
118 live object. */ | |
119 HeapWord* first_dead = space()->end(); /* The first dead object. */ | |
120 LiveRange* liveRange = NULL; /* The current live range, recorded in the | |
121 first header of preceding free area. */ | |
122 _first_dead = first_dead; | |
123 | |
124 const intx interval = PrefetchScanIntervalInBytes; | |
125 | |
126 while (q < t) { | |
127 assert(oop(q)->mark()->is_marked() || oop(q)->mark()->is_unlocked() || | |
128 oop(q)->mark()->has_bias_pattern(), | |
129 "these are the only valid states during a mark sweep"); | |
130 if (oop(q)->is_gc_marked()) { | |
131 /* prefetch beyond q */ | |
132 Prefetch::write(q, interval); | |
133 size_t size = oop(q)->size(); | |
134 | |
135 size_t compaction_max_size = pointer_delta(compact_end, compact_top); | |
136 | |
137 // This should only happen if a space in the young gen overflows the | |
138 // old gen. If that should happen, we null out the start_array, because | |
139 // the young spaces are not covered by one. | |
140 while(size > compaction_max_size) { | |
141 // First record the last compact_top | |
142 dest->set_compaction_top(compact_top); | |
143 | |
144 // Advance to the next compaction decorator | |
145 advance_destination_decorator(); | |
146 dest = destination_decorator(); | |
147 | |
148 // Update compaction info | |
149 start_array = dest->start_array(); | |
150 compact_top = dest->compaction_top(); | |
151 compact_end = dest->space()->end(); | |
152 assert(compact_top == dest->space()->bottom(), "Advanced to space already in use"); | |
153 assert(compact_end > compact_top, "Must always be space remaining"); | |
154 compaction_max_size = | |
155 pointer_delta(compact_end, compact_top); | |
156 } | |
157 | |
158 // store the forwarding pointer into the mark word | |
159 if (q != compact_top) { | |
160 oop(q)->forward_to(oop(compact_top)); | |
161 assert(oop(q)->is_gc_marked(), "encoding the pointer should preserve the mark"); | |
162 } else { | |
374
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163 // if the object isn't moving we can just set the mark to the default |
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164 // mark and handle it specially later on. |
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165 oop(q)->init_mark(); |
0 | 166 assert(oop(q)->forwardee() == NULL, "should be forwarded to NULL"); |
167 } | |
168 | |
169 // Update object start array | |
374
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170 if (start_array) { |
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171 start_array->allocate_block(compact_top); |
0 | 172 } |
173 | |
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174 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::register_live_oop(oop(q), size)); |
0 | 175 compact_top += size; |
176 assert(compact_top <= dest->space()->end(), | |
177 "Exceeding space in destination"); | |
178 | |
179 q += size; | |
180 end_of_live = q; | |
181 } else { | |
182 /* run over all the contiguous dead objects */ | |
183 HeapWord* end = q; | |
184 do { | |
185 /* prefetch beyond end */ | |
186 Prefetch::write(end, interval); | |
187 end += oop(end)->size(); | |
188 } while (end < t && (!oop(end)->is_gc_marked())); | |
189 | |
190 /* see if we might want to pretend this object is alive so that | |
191 * we don't have to compact quite as often. | |
192 */ | |
193 if (allowed_deadspace > 0 && q == compact_top) { | |
194 size_t sz = pointer_delta(end, q); | |
195 if (insert_deadspace(allowed_deadspace, q, sz)) { | |
196 size_t compaction_max_size = pointer_delta(compact_end, compact_top); | |
197 | |
198 // This should only happen if a space in the young gen overflows the | |
199 // old gen. If that should happen, we null out the start_array, because | |
200 // the young spaces are not covered by one. | |
201 while (sz > compaction_max_size) { | |
202 // First record the last compact_top | |
203 dest->set_compaction_top(compact_top); | |
204 | |
205 // Advance to the next compaction decorator | |
206 advance_destination_decorator(); | |
207 dest = destination_decorator(); | |
208 | |
209 // Update compaction info | |
210 start_array = dest->start_array(); | |
211 compact_top = dest->compaction_top(); | |
212 compact_end = dest->space()->end(); | |
213 assert(compact_top == dest->space()->bottom(), "Advanced to space already in use"); | |
214 assert(compact_end > compact_top, "Must always be space remaining"); | |
215 compaction_max_size = | |
216 pointer_delta(compact_end, compact_top); | |
217 } | |
218 | |
219 // store the forwarding pointer into the mark word | |
220 if (q != compact_top) { | |
221 oop(q)->forward_to(oop(compact_top)); | |
222 assert(oop(q)->is_gc_marked(), "encoding the pointer should preserve the mark"); | |
223 } else { | |
224 // if the object isn't moving we can just set the mark to the default | |
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225 // mark and handle it specially later on. |
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226 oop(q)->init_mark(); |
0 | 227 assert(oop(q)->forwardee() == NULL, "should be forwarded to NULL"); |
228 } | |
229 | |
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230 // Update object start array |
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231 if (start_array) { |
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232 start_array->allocate_block(compact_top); |
0 | 233 } |
234 | |
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235 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::register_live_oop(oop(q), sz)); |
0 | 236 compact_top += sz; |
237 assert(compact_top <= dest->space()->end(), | |
238 "Exceeding space in destination"); | |
239 | |
240 q = end; | |
241 end_of_live = end; | |
242 continue; | |
243 } | |
244 } | |
245 | |
246 /* for the previous LiveRange, record the end of the live objects. */ | |
247 if (liveRange) { | |
248 liveRange->set_end(q); | |
249 } | |
250 | |
251 /* record the current LiveRange object. | |
252 * liveRange->start() is overlaid on the mark word. | |
253 */ | |
254 liveRange = (LiveRange*)q; | |
255 liveRange->set_start(end); | |
256 liveRange->set_end(end); | |
257 | |
258 /* see if this is the first dead region. */ | |
259 if (q < first_dead) { | |
260 first_dead = q; | |
261 } | |
262 | |
263 /* move on to the next object */ | |
264 q = end; | |
265 } | |
266 } | |
267 | |
268 assert(q == t, "just checking"); | |
269 if (liveRange != NULL) { | |
270 liveRange->set_end(q); | |
271 } | |
272 _end_of_live = end_of_live; | |
273 if (end_of_live < first_dead) { | |
274 first_dead = end_of_live; | |
275 } | |
276 _first_dead = first_dead; | |
277 | |
278 // Update compaction top | |
279 dest->set_compaction_top(compact_top); | |
280 } | |
281 | |
438 | 282 bool PSMarkSweepDecorator::insert_deadspace(size_t& allowed_deadspace_words, |
283 HeapWord* q, size_t deadlength) { | |
284 if (allowed_deadspace_words >= deadlength) { | |
285 allowed_deadspace_words -= deadlength; | |
481
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286 CollectedHeap::fill_with_object(q, deadlength); |
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287 oop(q)->set_mark(oop(q)->mark()->set_marked()); |
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288 assert((int) deadlength == oop(q)->size(), "bad filler object size"); |
0 | 289 // Recall that we required "q == compaction_top". |
290 return true; | |
291 } else { | |
292 allowed_deadspace_words = 0; | |
293 return false; | |
294 } | |
295 } | |
296 | |
297 void PSMarkSweepDecorator::adjust_pointers() { | |
298 // adjust all the interior pointers to point at the new locations of objects | |
299 // Used by MarkSweep::mark_sweep_phase3() | |
300 | |
301 HeapWord* q = space()->bottom(); | |
302 HeapWord* t = _end_of_live; // Established by "prepare_for_compaction". | |
303 | |
304 assert(_first_dead <= _end_of_live, "Stands to reason, no?"); | |
305 | |
306 if (q < t && _first_dead > q && | |
307 !oop(q)->is_gc_marked()) { | |
308 // we have a chunk of the space which hasn't moved and we've | |
309 // reinitialized the mark word during the previous pass, so we can't | |
310 // use is_gc_marked for the traversal. | |
311 HeapWord* end = _first_dead; | |
312 | |
313 while (q < end) { | |
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314 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::track_interior_pointers(oop(q))); |
0 | 315 // point all the oops to the new location |
316 size_t size = oop(q)->adjust_pointers(); | |
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317 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::check_interior_pointers()); |
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318 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::validate_live_oop(oop(q), size)); |
0 | 319 q += size; |
320 } | |
321 | |
322 if (_first_dead == t) { | |
323 q = t; | |
324 } else { | |
325 // $$$ This is funky. Using this to read the previously written | |
326 // LiveRange. See also use below. | |
327 q = (HeapWord*)oop(_first_dead)->mark()->decode_pointer(); | |
328 } | |
329 } | |
330 const intx interval = PrefetchScanIntervalInBytes; | |
331 | |
332 debug_only(HeapWord* prev_q = NULL); | |
333 while (q < t) { | |
334 // prefetch beyond q | |
335 Prefetch::write(q, interval); | |
336 if (oop(q)->is_gc_marked()) { | |
337 // q is alive | |
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338 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::track_interior_pointers(oop(q))); |
0 | 339 // point all the oops to the new location |
340 size_t size = oop(q)->adjust_pointers(); | |
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341 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::check_interior_pointers()); |
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342 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::validate_live_oop(oop(q), size)); |
0 | 343 debug_only(prev_q = q); |
344 q += size; | |
345 } else { | |
346 // q is not a live object, so its mark should point at the next | |
347 // live object | |
348 debug_only(prev_q = q); | |
349 q = (HeapWord*) oop(q)->mark()->decode_pointer(); | |
350 assert(q > prev_q, "we should be moving forward through memory"); | |
351 } | |
352 } | |
353 | |
354 assert(q == t, "just checking"); | |
355 } | |
356 | |
357 void PSMarkSweepDecorator::compact(bool mangle_free_space ) { | |
358 // Copy all live objects to their new location | |
359 // Used by MarkSweep::mark_sweep_phase4() | |
360 | |
361 HeapWord* q = space()->bottom(); | |
362 HeapWord* const t = _end_of_live; | |
363 debug_only(HeapWord* prev_q = NULL); | |
364 | |
365 if (q < t && _first_dead > q && | |
366 !oop(q)->is_gc_marked()) { | |
367 #ifdef ASSERT | |
368 // we have a chunk of the space which hasn't moved and we've reinitialized the | |
369 // mark word during the previous pass, so we can't use is_gc_marked for the | |
370 // traversal. | |
371 HeapWord* const end = _first_dead; | |
372 | |
373 while (q < end) { | |
374 size_t size = oop(q)->size(); | |
375 assert(!oop(q)->is_gc_marked(), "should be unmarked (special dense prefix handling)"); | |
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376 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::live_oop_moved_to(q, size, q)); |
0 | 377 debug_only(prev_q = q); |
378 q += size; | |
379 } | |
380 #endif | |
381 | |
382 if (_first_dead == t) { | |
383 q = t; | |
384 } else { | |
385 // $$$ Funky | |
386 q = (HeapWord*) oop(_first_dead)->mark()->decode_pointer(); | |
387 } | |
388 } | |
389 | |
390 const intx scan_interval = PrefetchScanIntervalInBytes; | |
391 const intx copy_interval = PrefetchCopyIntervalInBytes; | |
392 | |
393 while (q < t) { | |
394 if (!oop(q)->is_gc_marked()) { | |
395 // mark is pointer to next marked oop | |
396 debug_only(prev_q = q); | |
397 q = (HeapWord*) oop(q)->mark()->decode_pointer(); | |
398 assert(q > prev_q, "we should be moving forward through memory"); | |
399 } else { | |
400 // prefetch beyond q | |
401 Prefetch::read(q, scan_interval); | |
402 | |
403 // size and destination | |
404 size_t size = oop(q)->size(); | |
405 HeapWord* compaction_top = (HeapWord*)oop(q)->forwardee(); | |
406 | |
407 // prefetch beyond compaction_top | |
408 Prefetch::write(compaction_top, copy_interval); | |
409 | |
410 // copy object and reinit its mark | |
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411 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::live_oop_moved_to(q, size, compaction_top)); |
0 | 412 assert(q != compaction_top, "everything in this pass should be moving"); |
413 Copy::aligned_conjoint_words(q, compaction_top, size); | |
414 oop(compaction_top)->init_mark(); | |
415 assert(oop(compaction_top)->klass() != NULL, "should have a class"); | |
416 | |
417 debug_only(prev_q = q); | |
418 q += size; | |
419 } | |
420 } | |
421 | |
422 assert(compaction_top() >= space()->bottom() && compaction_top() <= space()->end(), | |
423 "should point inside space"); | |
424 space()->set_top(compaction_top()); | |
425 | |
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426 if (mangle_free_space) { |
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427 space()->mangle_unused_area(); |
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428 } |
0 | 429 } |