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annotate src/share/vm/gc_implementation/parallelScavenge/psMarkSweepDecorator.cpp @ 1552:c18cbe5936b8
6941466: Oracle rebranding changes for Hotspot repositories
Summary: Change all the Sun copyrights to Oracle copyright
Reviewed-by: ohair
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date | Thu, 27 May 2010 19:08:38 -0700 |
parents | 0fbdb4381b99 |
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0 | 1 /* |
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2 * Copyright (c) 2001, 2009, 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 * | |
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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 | |
25 # include "incls/_precompiled.incl" | |
26 # include "incls/_psMarkSweepDecorator.cpp.incl" | |
27 | |
28 PSMarkSweepDecorator* PSMarkSweepDecorator::_destination_decorator = NULL; | |
29 | |
30 | |
31 void PSMarkSweepDecorator::set_destination_decorator_tenured() { | |
32 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
33 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
34 | |
35 _destination_decorator = heap->old_gen()->object_mark_sweep(); | |
36 } | |
37 | |
38 void PSMarkSweepDecorator::set_destination_decorator_perm_gen() { | |
39 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
40 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
41 | |
42 _destination_decorator = heap->perm_gen()->object_mark_sweep(); | |
43 } | |
44 | |
45 void PSMarkSweepDecorator::advance_destination_decorator() { | |
46 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
47 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
48 | |
49 assert(_destination_decorator != NULL, "Sanity"); | |
50 guarantee(_destination_decorator != heap->perm_gen()->object_mark_sweep(), "Cannot advance perm gen decorator"); | |
51 | |
52 PSMarkSweepDecorator* first = heap->old_gen()->object_mark_sweep(); | |
53 PSMarkSweepDecorator* second = heap->young_gen()->eden_mark_sweep(); | |
54 PSMarkSweepDecorator* third = heap->young_gen()->from_mark_sweep(); | |
55 PSMarkSweepDecorator* fourth = heap->young_gen()->to_mark_sweep(); | |
56 | |
57 if ( _destination_decorator == first ) { | |
58 _destination_decorator = second; | |
59 } else if ( _destination_decorator == second ) { | |
60 _destination_decorator = third; | |
61 } else if ( _destination_decorator == third ) { | |
62 _destination_decorator = fourth; | |
63 } else { | |
64 fatal("PSMarkSweep attempting to advance past last compaction area"); | |
65 } | |
66 } | |
67 | |
68 PSMarkSweepDecorator* PSMarkSweepDecorator::destination_decorator() { | |
69 assert(_destination_decorator != NULL, "Sanity"); | |
70 | |
71 return _destination_decorator; | |
72 } | |
73 | |
74 // FIX ME FIX ME FIX ME FIX ME!!!!!!!!! | |
75 // The object forwarding code is duplicated. Factor this out!!!!! | |
76 // | |
77 // This method "precompacts" objects inside its space to dest. It places forwarding | |
78 // pointers into markOops for use by adjust_pointers. If "dest" should overflow, we | |
79 // finish by compacting into our own space. | |
80 | |
81 void PSMarkSweepDecorator::precompact() { | |
82 // Reset our own compact top. | |
83 set_compaction_top(space()->bottom()); | |
84 | |
85 /* We allow some amount of garbage towards the bottom of the space, so | |
86 * we don't start compacting before there is a significant gain to be made. | |
87 * Occasionally, we want to ensure a full compaction, which is determined | |
88 * by the MarkSweepAlwaysCompactCount parameter. This is a significant | |
89 * performance improvement! | |
90 */ | |
91 bool skip_dead = ((PSMarkSweep::total_invocations() % MarkSweepAlwaysCompactCount) != 0); | |
92 | |
438 | 93 size_t allowed_deadspace = 0; |
0 | 94 if (skip_dead) { |
438 | 95 const size_t ratio = allowed_dead_ratio(); |
96 allowed_deadspace = space()->capacity_in_words() * ratio / 100; | |
0 | 97 } |
98 | |
99 // Fetch the current destination decorator | |
100 PSMarkSweepDecorator* dest = destination_decorator(); | |
101 ObjectStartArray* start_array = dest->start_array(); | |
102 | |
103 HeapWord* compact_top = dest->compaction_top(); | |
104 HeapWord* compact_end = dest->space()->end(); | |
105 | |
106 HeapWord* q = space()->bottom(); | |
107 HeapWord* t = space()->top(); | |
108 | |
109 HeapWord* end_of_live= q; /* One byte beyond the last byte of the last | |
110 live object. */ | |
111 HeapWord* first_dead = space()->end(); /* The first dead object. */ | |
112 LiveRange* liveRange = NULL; /* The current live range, recorded in the | |
113 first header of preceding free area. */ | |
114 _first_dead = first_dead; | |
115 | |
116 const intx interval = PrefetchScanIntervalInBytes; | |
117 | |
118 while (q < t) { | |
119 assert(oop(q)->mark()->is_marked() || oop(q)->mark()->is_unlocked() || | |
120 oop(q)->mark()->has_bias_pattern(), | |
121 "these are the only valid states during a mark sweep"); | |
122 if (oop(q)->is_gc_marked()) { | |
123 /* prefetch beyond q */ | |
124 Prefetch::write(q, interval); | |
125 size_t size = oop(q)->size(); | |
126 | |
127 size_t compaction_max_size = pointer_delta(compact_end, compact_top); | |
128 | |
129 // This should only happen if a space in the young gen overflows the | |
130 // old gen. If that should happen, we null out the start_array, because | |
131 // the young spaces are not covered by one. | |
132 while(size > compaction_max_size) { | |
133 // First record the last compact_top | |
134 dest->set_compaction_top(compact_top); | |
135 | |
136 // Advance to the next compaction decorator | |
137 advance_destination_decorator(); | |
138 dest = destination_decorator(); | |
139 | |
140 // Update compaction info | |
141 start_array = dest->start_array(); | |
142 compact_top = dest->compaction_top(); | |
143 compact_end = dest->space()->end(); | |
144 assert(compact_top == dest->space()->bottom(), "Advanced to space already in use"); | |
145 assert(compact_end > compact_top, "Must always be space remaining"); | |
146 compaction_max_size = | |
147 pointer_delta(compact_end, compact_top); | |
148 } | |
149 | |
150 // store the forwarding pointer into the mark word | |
151 if (q != compact_top) { | |
152 oop(q)->forward_to(oop(compact_top)); | |
153 assert(oop(q)->is_gc_marked(), "encoding the pointer should preserve the mark"); | |
154 } else { | |
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155 // if the object isn't moving we can just set the mark to the default |
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156 // mark and handle it specially later on. |
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157 oop(q)->init_mark(); |
0 | 158 assert(oop(q)->forwardee() == NULL, "should be forwarded to NULL"); |
159 } | |
160 | |
161 // Update object start array | |
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162 if (start_array) { |
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163 start_array->allocate_block(compact_top); |
0 | 164 } |
165 | |
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166 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::register_live_oop(oop(q), size)); |
0 | 167 compact_top += size; |
168 assert(compact_top <= dest->space()->end(), | |
169 "Exceeding space in destination"); | |
170 | |
171 q += size; | |
172 end_of_live = q; | |
173 } else { | |
174 /* run over all the contiguous dead objects */ | |
175 HeapWord* end = q; | |
176 do { | |
177 /* prefetch beyond end */ | |
178 Prefetch::write(end, interval); | |
179 end += oop(end)->size(); | |
180 } while (end < t && (!oop(end)->is_gc_marked())); | |
181 | |
182 /* see if we might want to pretend this object is alive so that | |
183 * we don't have to compact quite as often. | |
184 */ | |
185 if (allowed_deadspace > 0 && q == compact_top) { | |
186 size_t sz = pointer_delta(end, q); | |
187 if (insert_deadspace(allowed_deadspace, q, sz)) { | |
188 size_t compaction_max_size = pointer_delta(compact_end, compact_top); | |
189 | |
190 // This should only happen if a space in the young gen overflows the | |
191 // old gen. If that should happen, we null out the start_array, because | |
192 // the young spaces are not covered by one. | |
193 while (sz > compaction_max_size) { | |
194 // First record the last compact_top | |
195 dest->set_compaction_top(compact_top); | |
196 | |
197 // Advance to the next compaction decorator | |
198 advance_destination_decorator(); | |
199 dest = destination_decorator(); | |
200 | |
201 // Update compaction info | |
202 start_array = dest->start_array(); | |
203 compact_top = dest->compaction_top(); | |
204 compact_end = dest->space()->end(); | |
205 assert(compact_top == dest->space()->bottom(), "Advanced to space already in use"); | |
206 assert(compact_end > compact_top, "Must always be space remaining"); | |
207 compaction_max_size = | |
208 pointer_delta(compact_end, compact_top); | |
209 } | |
210 | |
211 // store the forwarding pointer into the mark word | |
212 if (q != compact_top) { | |
213 oop(q)->forward_to(oop(compact_top)); | |
214 assert(oop(q)->is_gc_marked(), "encoding the pointer should preserve the mark"); | |
215 } else { | |
216 // if the object isn't moving we can just set the mark to the default | |
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217 // mark and handle it specially later on. |
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218 oop(q)->init_mark(); |
0 | 219 assert(oop(q)->forwardee() == NULL, "should be forwarded to NULL"); |
220 } | |
221 | |
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222 // Update object start array |
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223 if (start_array) { |
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224 start_array->allocate_block(compact_top); |
0 | 225 } |
226 | |
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227 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::register_live_oop(oop(q), sz)); |
0 | 228 compact_top += sz; |
229 assert(compact_top <= dest->space()->end(), | |
230 "Exceeding space in destination"); | |
231 | |
232 q = end; | |
233 end_of_live = end; | |
234 continue; | |
235 } | |
236 } | |
237 | |
238 /* for the previous LiveRange, record the end of the live objects. */ | |
239 if (liveRange) { | |
240 liveRange->set_end(q); | |
241 } | |
242 | |
243 /* record the current LiveRange object. | |
244 * liveRange->start() is overlaid on the mark word. | |
245 */ | |
246 liveRange = (LiveRange*)q; | |
247 liveRange->set_start(end); | |
248 liveRange->set_end(end); | |
249 | |
250 /* see if this is the first dead region. */ | |
251 if (q < first_dead) { | |
252 first_dead = q; | |
253 } | |
254 | |
255 /* move on to the next object */ | |
256 q = end; | |
257 } | |
258 } | |
259 | |
260 assert(q == t, "just checking"); | |
261 if (liveRange != NULL) { | |
262 liveRange->set_end(q); | |
263 } | |
264 _end_of_live = end_of_live; | |
265 if (end_of_live < first_dead) { | |
266 first_dead = end_of_live; | |
267 } | |
268 _first_dead = first_dead; | |
269 | |
270 // Update compaction top | |
271 dest->set_compaction_top(compact_top); | |
272 } | |
273 | |
438 | 274 bool PSMarkSweepDecorator::insert_deadspace(size_t& allowed_deadspace_words, |
275 HeapWord* q, size_t deadlength) { | |
276 if (allowed_deadspace_words >= deadlength) { | |
277 allowed_deadspace_words -= deadlength; | |
481
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278 CollectedHeap::fill_with_object(q, deadlength); |
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279 oop(q)->set_mark(oop(q)->mark()->set_marked()); |
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280 assert((int) deadlength == oop(q)->size(), "bad filler object size"); |
0 | 281 // Recall that we required "q == compaction_top". |
282 return true; | |
283 } else { | |
284 allowed_deadspace_words = 0; | |
285 return false; | |
286 } | |
287 } | |
288 | |
289 void PSMarkSweepDecorator::adjust_pointers() { | |
290 // adjust all the interior pointers to point at the new locations of objects | |
291 // Used by MarkSweep::mark_sweep_phase3() | |
292 | |
293 HeapWord* q = space()->bottom(); | |
294 HeapWord* t = _end_of_live; // Established by "prepare_for_compaction". | |
295 | |
296 assert(_first_dead <= _end_of_live, "Stands to reason, no?"); | |
297 | |
298 if (q < t && _first_dead > q && | |
299 !oop(q)->is_gc_marked()) { | |
300 // we have a chunk of the space which hasn't moved and we've | |
301 // reinitialized the mark word during the previous pass, so we can't | |
302 // use is_gc_marked for the traversal. | |
303 HeapWord* end = _first_dead; | |
304 | |
305 while (q < end) { | |
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306 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::track_interior_pointers(oop(q))); |
0 | 307 // point all the oops to the new location |
308 size_t size = oop(q)->adjust_pointers(); | |
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309 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::check_interior_pointers()); |
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310 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::validate_live_oop(oop(q), size)); |
0 | 311 q += size; |
312 } | |
313 | |
314 if (_first_dead == t) { | |
315 q = t; | |
316 } else { | |
317 // $$$ This is funky. Using this to read the previously written | |
318 // LiveRange. See also use below. | |
319 q = (HeapWord*)oop(_first_dead)->mark()->decode_pointer(); | |
320 } | |
321 } | |
322 const intx interval = PrefetchScanIntervalInBytes; | |
323 | |
324 debug_only(HeapWord* prev_q = NULL); | |
325 while (q < t) { | |
326 // prefetch beyond q | |
327 Prefetch::write(q, interval); | |
328 if (oop(q)->is_gc_marked()) { | |
329 // q is alive | |
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330 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::track_interior_pointers(oop(q))); |
0 | 331 // point all the oops to the new location |
332 size_t size = oop(q)->adjust_pointers(); | |
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333 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::check_interior_pointers()); |
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334 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::validate_live_oop(oop(q), size)); |
0 | 335 debug_only(prev_q = q); |
336 q += size; | |
337 } else { | |
338 // q is not a live object, so its mark should point at the next | |
339 // live object | |
340 debug_only(prev_q = q); | |
341 q = (HeapWord*) oop(q)->mark()->decode_pointer(); | |
342 assert(q > prev_q, "we should be moving forward through memory"); | |
343 } | |
344 } | |
345 | |
346 assert(q == t, "just checking"); | |
347 } | |
348 | |
349 void PSMarkSweepDecorator::compact(bool mangle_free_space ) { | |
350 // Copy all live objects to their new location | |
351 // Used by MarkSweep::mark_sweep_phase4() | |
352 | |
353 HeapWord* q = space()->bottom(); | |
354 HeapWord* const t = _end_of_live; | |
355 debug_only(HeapWord* prev_q = NULL); | |
356 | |
357 if (q < t && _first_dead > q && | |
358 !oop(q)->is_gc_marked()) { | |
359 #ifdef ASSERT | |
360 // we have a chunk of the space which hasn't moved and we've reinitialized the | |
361 // mark word during the previous pass, so we can't use is_gc_marked for the | |
362 // traversal. | |
363 HeapWord* const end = _first_dead; | |
364 | |
365 while (q < end) { | |
366 size_t size = oop(q)->size(); | |
367 assert(!oop(q)->is_gc_marked(), "should be unmarked (special dense prefix handling)"); | |
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368 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::live_oop_moved_to(q, size, q)); |
0 | 369 debug_only(prev_q = q); |
370 q += size; | |
371 } | |
372 #endif | |
373 | |
374 if (_first_dead == t) { | |
375 q = t; | |
376 } else { | |
377 // $$$ Funky | |
378 q = (HeapWord*) oop(_first_dead)->mark()->decode_pointer(); | |
379 } | |
380 } | |
381 | |
382 const intx scan_interval = PrefetchScanIntervalInBytes; | |
383 const intx copy_interval = PrefetchCopyIntervalInBytes; | |
384 | |
385 while (q < t) { | |
386 if (!oop(q)->is_gc_marked()) { | |
387 // mark is pointer to next marked oop | |
388 debug_only(prev_q = q); | |
389 q = (HeapWord*) oop(q)->mark()->decode_pointer(); | |
390 assert(q > prev_q, "we should be moving forward through memory"); | |
391 } else { | |
392 // prefetch beyond q | |
393 Prefetch::read(q, scan_interval); | |
394 | |
395 // size and destination | |
396 size_t size = oop(q)->size(); | |
397 HeapWord* compaction_top = (HeapWord*)oop(q)->forwardee(); | |
398 | |
399 // prefetch beyond compaction_top | |
400 Prefetch::write(compaction_top, copy_interval); | |
401 | |
402 // copy object and reinit its mark | |
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403 VALIDATE_MARK_SWEEP_ONLY(MarkSweep::live_oop_moved_to(q, size, compaction_top)); |
0 | 404 assert(q != compaction_top, "everything in this pass should be moving"); |
405 Copy::aligned_conjoint_words(q, compaction_top, size); | |
406 oop(compaction_top)->init_mark(); | |
407 assert(oop(compaction_top)->klass() != NULL, "should have a class"); | |
408 | |
409 debug_only(prev_q = q); | |
410 q += size; | |
411 } | |
412 } | |
413 | |
414 assert(compaction_top() >= space()->bottom() && compaction_top() <= space()->end(), | |
415 "should point inside space"); | |
416 space()->set_top(compaction_top()); | |
417 | |
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418 if (mangle_free_space) { |
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419 space()->mangle_unused_area(); |
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420 } |
0 | 421 } |