Mercurial > hg > graal-jvmci-8
annotate src/share/vm/gc_implementation/parallelScavenge/cardTableExtension.cpp @ 1315:c385bf94cfb8
6935839: excessive marking stack growth during full gcs
Summary: process one item at a time from the objarray stack/queue
Reviewed-by: apetrusenko, tonyp
author | jcoomes |
---|---|
date | Thu, 18 Mar 2010 13:31:51 -0700 |
parents | 98cb887364d3 |
children | c18cbe5936b8 |
rev | line source |
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0 | 1 /* |
196 | 2 * Copyright 2001-2008 Sun Microsystems, Inc. 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 * | |
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/_cardTableExtension.cpp.incl" | |
27 | |
28 // Checks an individual oop for missing precise marks. Mark | |
29 // may be either dirty or newgen. | |
30 class CheckForUnmarkedOops : public OopClosure { | |
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31 private: |
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32 PSYoungGen* _young_gen; |
0 | 33 CardTableExtension* _card_table; |
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34 HeapWord* _unmarked_addr; |
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35 jbyte* _unmarked_card; |
0 | 36 |
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37 protected: |
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38 template <class T> void do_oop_work(T* p) { |
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39 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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40 if (_young_gen->is_in_reserved(obj) && |
0 | 41 !_card_table->addr_is_marked_imprecise(p)) { |
42 // Don't overwrite the first missing card mark | |
43 if (_unmarked_addr == NULL) { | |
44 _unmarked_addr = (HeapWord*)p; | |
45 _unmarked_card = _card_table->byte_for(p); | |
46 } | |
47 } | |
48 } | |
49 | |
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50 public: |
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51 CheckForUnmarkedOops(PSYoungGen* young_gen, CardTableExtension* card_table) : |
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52 _young_gen(young_gen), _card_table(card_table), _unmarked_addr(NULL) { } |
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53 |
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54 virtual void do_oop(oop* p) { CheckForUnmarkedOops::do_oop_work(p); } |
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55 virtual void do_oop(narrowOop* p) { CheckForUnmarkedOops::do_oop_work(p); } |
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56 |
0 | 57 bool has_unmarked_oop() { |
58 return _unmarked_addr != NULL; | |
59 } | |
60 }; | |
61 | |
62 // Checks all objects for the existance of some type of mark, | |
63 // precise or imprecise, dirty or newgen. | |
64 class CheckForUnmarkedObjects : public ObjectClosure { | |
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65 private: |
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66 PSYoungGen* _young_gen; |
0 | 67 CardTableExtension* _card_table; |
68 | |
69 public: | |
70 CheckForUnmarkedObjects() { | |
71 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
72 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
73 | |
74 _young_gen = heap->young_gen(); | |
75 _card_table = (CardTableExtension*)heap->barrier_set(); | |
76 // No point in asserting barrier set type here. Need to make CardTableExtension | |
77 // a unique barrier set type. | |
78 } | |
79 | |
80 // Card marks are not precise. The current system can leave us with | |
605 | 81 // a mismash of precise marks and beginning of object marks. This means |
0 | 82 // we test for missing precise marks first. If any are found, we don't |
83 // fail unless the object head is also unmarked. | |
84 virtual void do_object(oop obj) { | |
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85 CheckForUnmarkedOops object_check(_young_gen, _card_table); |
0 | 86 obj->oop_iterate(&object_check); |
87 if (object_check.has_unmarked_oop()) { | |
88 assert(_card_table->addr_is_marked_imprecise(obj), "Found unmarked young_gen object"); | |
89 } | |
90 } | |
91 }; | |
92 | |
93 // Checks for precise marking of oops as newgen. | |
94 class CheckForPreciseMarks : public OopClosure { | |
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95 private: |
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96 PSYoungGen* _young_gen; |
0 | 97 CardTableExtension* _card_table; |
98 | |
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99 protected: |
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100 template <class T> void do_oop_work(T* p) { |
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101 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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102 if (_young_gen->is_in_reserved(obj)) { |
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103 assert(_card_table->addr_is_marked_precise(p), "Found unmarked precise oop"); |
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104 _card_table->set_card_newgen(p); |
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105 } |
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106 } |
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107 |
0 | 108 public: |
109 CheckForPreciseMarks( PSYoungGen* young_gen, CardTableExtension* card_table ) : | |
110 _young_gen(young_gen), _card_table(card_table) { } | |
111 | |
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112 virtual void do_oop(oop* p) { CheckForPreciseMarks::do_oop_work(p); } |
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113 virtual void do_oop(narrowOop* p) { CheckForPreciseMarks::do_oop_work(p); } |
0 | 114 }; |
115 | |
116 // We get passed the space_top value to prevent us from traversing into | |
117 // the old_gen promotion labs, which cannot be safely parsed. | |
118 void CardTableExtension::scavenge_contents(ObjectStartArray* start_array, | |
119 MutableSpace* sp, | |
120 HeapWord* space_top, | |
121 PSPromotionManager* pm) | |
122 { | |
123 assert(start_array != NULL && sp != NULL && pm != NULL, "Sanity"); | |
124 assert(start_array->covered_region().contains(sp->used_region()), | |
125 "ObjectStartArray does not cover space"); | |
126 bool depth_first = pm->depth_first(); | |
127 | |
128 if (sp->not_empty()) { | |
129 oop* sp_top = (oop*)space_top; | |
130 oop* prev_top = NULL; | |
131 jbyte* current_card = byte_for(sp->bottom()); | |
132 jbyte* end_card = byte_for(sp_top - 1); // sp_top is exclusive | |
133 // scan card marking array | |
134 while (current_card <= end_card) { | |
135 jbyte value = *current_card; | |
136 // skip clean cards | |
137 if (card_is_clean(value)) { | |
138 current_card++; | |
139 } else { | |
140 // we found a non-clean card | |
141 jbyte* first_nonclean_card = current_card++; | |
142 oop* bottom = (oop*)addr_for(first_nonclean_card); | |
143 // find object starting on card | |
144 oop* bottom_obj = (oop*)start_array->object_start((HeapWord*)bottom); | |
145 // bottom_obj = (oop*)start_array->object_start((HeapWord*)bottom); | |
146 assert(bottom_obj <= bottom, "just checking"); | |
147 // make sure we don't scan oops we already looked at | |
148 if (bottom < prev_top) bottom = prev_top; | |
149 // figure out when to stop scanning | |
150 jbyte* first_clean_card; | |
151 oop* top; | |
152 bool restart_scanning; | |
153 do { | |
154 restart_scanning = false; | |
155 // find a clean card | |
156 while (current_card <= end_card) { | |
157 value = *current_card; | |
158 if (card_is_clean(value)) break; | |
159 current_card++; | |
160 } | |
161 // check if we reached the end, if so we are done | |
162 if (current_card >= end_card) { | |
163 first_clean_card = end_card + 1; | |
164 current_card++; | |
165 top = sp_top; | |
166 } else { | |
167 // we have a clean card, find object starting on that card | |
168 first_clean_card = current_card++; | |
169 top = (oop*)addr_for(first_clean_card); | |
170 oop* top_obj = (oop*)start_array->object_start((HeapWord*)top); | |
171 // top_obj = (oop*)start_array->object_start((HeapWord*)top); | |
172 assert(top_obj <= top, "just checking"); | |
173 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) { | |
174 // an arrayOop is starting on the clean card - since we do exact store | |
175 // checks for objArrays we are done | |
176 } else { | |
177 // otherwise, it is possible that the object starting on the clean card | |
178 // spans the entire card, and that the store happened on a later card. | |
179 // figure out where the object ends | |
180 top = top_obj + oop(top_obj)->size(); | |
181 jbyte* top_card = CardTableModRefBS::byte_for(top - 1); // top is exclusive | |
182 if (top_card > first_clean_card) { | |
183 // object ends a different card | |
184 current_card = top_card + 1; | |
185 if (card_is_clean(*top_card)) { | |
186 // the ending card is clean, we are done | |
187 first_clean_card = top_card; | |
188 } else { | |
189 // the ending card is not clean, continue scanning at start of do-while | |
190 restart_scanning = true; | |
191 } | |
192 } else { | |
193 // object ends on the clean card, we are done. | |
194 assert(first_clean_card == top_card, "just checking"); | |
195 } | |
196 } | |
197 } | |
198 } while (restart_scanning); | |
199 // we know which cards to scan, now clear them | |
200 while (first_nonclean_card < first_clean_card) { | |
201 *first_nonclean_card++ = clean_card; | |
202 } | |
203 // scan oops in objects | |
204 // hoisted the if (depth_first) check out of the loop | |
205 if (depth_first){ | |
206 do { | |
207 oop(bottom_obj)->push_contents(pm); | |
208 bottom_obj += oop(bottom_obj)->size(); | |
209 assert(bottom_obj <= sp_top, "just checking"); | |
210 } while (bottom_obj < top); | |
211 pm->drain_stacks_cond_depth(); | |
212 } else { | |
213 do { | |
214 oop(bottom_obj)->copy_contents(pm); | |
215 bottom_obj += oop(bottom_obj)->size(); | |
216 assert(bottom_obj <= sp_top, "just checking"); | |
217 } while (bottom_obj < top); | |
218 } | |
219 // remember top oop* scanned | |
220 prev_top = top; | |
221 } | |
222 } | |
223 } | |
224 } | |
225 | |
226 void CardTableExtension::scavenge_contents_parallel(ObjectStartArray* start_array, | |
227 MutableSpace* sp, | |
228 HeapWord* space_top, | |
229 PSPromotionManager* pm, | |
230 uint stripe_number) { | |
231 int ssize = 128; // Naked constant! Work unit = 64k. | |
232 int dirty_card_count = 0; | |
233 bool depth_first = pm->depth_first(); | |
234 | |
235 oop* sp_top = (oop*)space_top; | |
236 jbyte* start_card = byte_for(sp->bottom()); | |
237 jbyte* end_card = byte_for(sp_top - 1) + 1; | |
238 oop* last_scanned = NULL; // Prevent scanning objects more than once | |
239 for (jbyte* slice = start_card; slice < end_card; slice += ssize*ParallelGCThreads) { | |
240 jbyte* worker_start_card = slice + stripe_number * ssize; | |
241 if (worker_start_card >= end_card) | |
242 return; // We're done. | |
243 | |
244 jbyte* worker_end_card = worker_start_card + ssize; | |
245 if (worker_end_card > end_card) | |
246 worker_end_card = end_card; | |
247 | |
248 // We do not want to scan objects more than once. In order to accomplish | |
249 // this, we assert that any object with an object head inside our 'slice' | |
250 // belongs to us. We may need to extend the range of scanned cards if the | |
251 // last object continues into the next 'slice'. | |
252 // | |
253 // Note! ending cards are exclusive! | |
254 HeapWord* slice_start = addr_for(worker_start_card); | |
255 HeapWord* slice_end = MIN2((HeapWord*) sp_top, addr_for(worker_end_card)); | |
256 | |
257 // If there are not objects starting within the chunk, skip it. | |
258 if (!start_array->object_starts_in_range(slice_start, slice_end)) { | |
259 continue; | |
260 } | |
605 | 261 // Update our beginning addr |
0 | 262 HeapWord* first_object = start_array->object_start(slice_start); |
263 debug_only(oop* first_object_within_slice = (oop*) first_object;) | |
264 if (first_object < slice_start) { | |
265 last_scanned = (oop*)(first_object + oop(first_object)->size()); | |
266 debug_only(first_object_within_slice = last_scanned;) | |
267 worker_start_card = byte_for(last_scanned); | |
268 } | |
269 | |
270 // Update the ending addr | |
271 if (slice_end < (HeapWord*)sp_top) { | |
272 // The subtraction is important! An object may start precisely at slice_end. | |
273 HeapWord* last_object = start_array->object_start(slice_end - 1); | |
274 slice_end = last_object + oop(last_object)->size(); | |
275 // worker_end_card is exclusive, so bump it one past the end of last_object's | |
276 // covered span. | |
277 worker_end_card = byte_for(slice_end) + 1; | |
278 | |
279 if (worker_end_card > end_card) | |
280 worker_end_card = end_card; | |
281 } | |
282 | |
283 assert(slice_end <= (HeapWord*)sp_top, "Last object in slice crosses space boundary"); | |
284 assert(is_valid_card_address(worker_start_card), "Invalid worker start card"); | |
285 assert(is_valid_card_address(worker_end_card), "Invalid worker end card"); | |
286 // Note that worker_start_card >= worker_end_card is legal, and happens when | |
287 // an object spans an entire slice. | |
288 assert(worker_start_card <= end_card, "worker start card beyond end card"); | |
289 assert(worker_end_card <= end_card, "worker end card beyond end card"); | |
290 | |
291 jbyte* current_card = worker_start_card; | |
292 while (current_card < worker_end_card) { | |
293 // Find an unclean card. | |
294 while (current_card < worker_end_card && card_is_clean(*current_card)) { | |
295 current_card++; | |
296 } | |
297 jbyte* first_unclean_card = current_card; | |
298 | |
299 // Find the end of a run of contiguous unclean cards | |
300 while (current_card < worker_end_card && !card_is_clean(*current_card)) { | |
301 while (current_card < worker_end_card && !card_is_clean(*current_card)) { | |
302 current_card++; | |
303 } | |
304 | |
305 if (current_card < worker_end_card) { | |
306 // Some objects may be large enough to span several cards. If such | |
307 // an object has more than one dirty card, separated by a clean card, | |
308 // we will attempt to scan it twice. The test against "last_scanned" | |
309 // prevents the redundant object scan, but it does not prevent newly | |
310 // marked cards from being cleaned. | |
311 HeapWord* last_object_in_dirty_region = start_array->object_start(addr_for(current_card)-1); | |
312 size_t size_of_last_object = oop(last_object_in_dirty_region)->size(); | |
313 HeapWord* end_of_last_object = last_object_in_dirty_region + size_of_last_object; | |
314 jbyte* ending_card_of_last_object = byte_for(end_of_last_object); | |
315 assert(ending_card_of_last_object <= worker_end_card, "ending_card_of_last_object is greater than worker_end_card"); | |
316 if (ending_card_of_last_object > current_card) { | |
317 // This means the object spans the next complete card. | |
318 // We need to bump the current_card to ending_card_of_last_object | |
319 current_card = ending_card_of_last_object; | |
320 } | |
321 } | |
322 } | |
323 jbyte* following_clean_card = current_card; | |
324 | |
325 if (first_unclean_card < worker_end_card) { | |
326 oop* p = (oop*) start_array->object_start(addr_for(first_unclean_card)); | |
327 assert((HeapWord*)p <= addr_for(first_unclean_card), "checking"); | |
328 // "p" should always be >= "last_scanned" because newly GC dirtied | |
329 // cards are no longer scanned again (see comment at end | |
330 // of loop on the increment of "current_card"). Test that | |
331 // hypothesis before removing this code. | |
332 // If this code is removed, deal with the first time through | |
333 // the loop when the last_scanned is the object starting in | |
334 // the previous slice. | |
335 assert((p >= last_scanned) || | |
336 (last_scanned == first_object_within_slice), | |
337 "Should no longer be possible"); | |
338 if (p < last_scanned) { | |
339 // Avoid scanning more than once; this can happen because | |
340 // newgen cards set by GC may a different set than the | |
341 // originally dirty set | |
342 p = last_scanned; | |
343 } | |
344 oop* to = (oop*)addr_for(following_clean_card); | |
345 | |
346 // Test slice_end first! | |
347 if ((HeapWord*)to > slice_end) { | |
348 to = (oop*)slice_end; | |
349 } else if (to > sp_top) { | |
350 to = sp_top; | |
351 } | |
352 | |
353 // we know which cards to scan, now clear them | |
354 if (first_unclean_card <= worker_start_card+1) | |
355 first_unclean_card = worker_start_card+1; | |
356 if (following_clean_card >= worker_end_card-1) | |
357 following_clean_card = worker_end_card-1; | |
358 | |
359 while (first_unclean_card < following_clean_card) { | |
360 *first_unclean_card++ = clean_card; | |
361 } | |
362 | |
363 const int interval = PrefetchScanIntervalInBytes; | |
364 // scan all objects in the range | |
365 if (interval != 0) { | |
366 // hoisted the if (depth_first) check out of the loop | |
367 if (depth_first) { | |
368 while (p < to) { | |
369 Prefetch::write(p, interval); | |
370 oop m = oop(p); | |
371 assert(m->is_oop_or_null(), "check for header"); | |
372 m->push_contents(pm); | |
373 p += m->size(); | |
374 } | |
375 pm->drain_stacks_cond_depth(); | |
376 } else { | |
377 while (p < to) { | |
378 Prefetch::write(p, interval); | |
379 oop m = oop(p); | |
380 assert(m->is_oop_or_null(), "check for header"); | |
381 m->copy_contents(pm); | |
382 p += m->size(); | |
383 } | |
384 } | |
385 } else { | |
386 // hoisted the if (depth_first) check out of the loop | |
387 if (depth_first) { | |
388 while (p < to) { | |
389 oop m = oop(p); | |
390 assert(m->is_oop_or_null(), "check for header"); | |
391 m->push_contents(pm); | |
392 p += m->size(); | |
393 } | |
394 pm->drain_stacks_cond_depth(); | |
395 } else { | |
396 while (p < to) { | |
397 oop m = oop(p); | |
398 assert(m->is_oop_or_null(), "check for header"); | |
399 m->copy_contents(pm); | |
400 p += m->size(); | |
401 } | |
402 } | |
403 } | |
404 last_scanned = p; | |
405 } | |
406 // "current_card" is still the "following_clean_card" or | |
407 // the current_card is >= the worker_end_card so the | |
408 // loop will not execute again. | |
409 assert((current_card == following_clean_card) || | |
410 (current_card >= worker_end_card), | |
411 "current_card should only be incremented if it still equals " | |
412 "following_clean_card"); | |
413 // Increment current_card so that it is not processed again. | |
414 // It may now be dirty because a old-to-young pointer was | |
415 // found on it an updated. If it is now dirty, it cannot be | |
416 // be safely cleaned in the next iteration. | |
417 current_card++; | |
418 } | |
419 } | |
420 } | |
421 | |
422 // This should be called before a scavenge. | |
423 void CardTableExtension::verify_all_young_refs_imprecise() { | |
424 CheckForUnmarkedObjects check; | |
425 | |
426 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
427 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
428 | |
429 PSOldGen* old_gen = heap->old_gen(); | |
430 PSPermGen* perm_gen = heap->perm_gen(); | |
431 | |
432 old_gen->object_iterate(&check); | |
433 perm_gen->object_iterate(&check); | |
434 } | |
435 | |
436 // This should be called immediately after a scavenge, before mutators resume. | |
437 void CardTableExtension::verify_all_young_refs_precise() { | |
438 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
439 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
440 | |
441 PSOldGen* old_gen = heap->old_gen(); | |
442 PSPermGen* perm_gen = heap->perm_gen(); | |
443 | |
444 CheckForPreciseMarks check(heap->young_gen(), (CardTableExtension*)heap->barrier_set()); | |
445 | |
446 old_gen->oop_iterate(&check); | |
447 perm_gen->oop_iterate(&check); | |
448 | |
449 verify_all_young_refs_precise_helper(old_gen->object_space()->used_region()); | |
450 verify_all_young_refs_precise_helper(perm_gen->object_space()->used_region()); | |
451 } | |
452 | |
453 void CardTableExtension::verify_all_young_refs_precise_helper(MemRegion mr) { | |
454 CardTableExtension* card_table = (CardTableExtension*)Universe::heap()->barrier_set(); | |
455 // FIX ME ASSERT HERE | |
456 | |
457 jbyte* bot = card_table->byte_for(mr.start()); | |
458 jbyte* top = card_table->byte_for(mr.end()); | |
459 while(bot <= top) { | |
460 assert(*bot == clean_card || *bot == verify_card, "Found unwanted or unknown card mark"); | |
461 if (*bot == verify_card) | |
462 *bot = youngergen_card; | |
463 bot++; | |
464 } | |
465 } | |
466 | |
467 bool CardTableExtension::addr_is_marked_imprecise(void *addr) { | |
468 jbyte* p = byte_for(addr); | |
469 jbyte val = *p; | |
470 | |
471 if (card_is_dirty(val)) | |
472 return true; | |
473 | |
474 if (card_is_newgen(val)) | |
475 return true; | |
476 | |
477 if (card_is_clean(val)) | |
478 return false; | |
479 | |
480 assert(false, "Found unhandled card mark type"); | |
481 | |
482 return false; | |
483 } | |
484 | |
485 // Also includes verify_card | |
486 bool CardTableExtension::addr_is_marked_precise(void *addr) { | |
487 jbyte* p = byte_for(addr); | |
488 jbyte val = *p; | |
489 | |
490 if (card_is_newgen(val)) | |
491 return true; | |
492 | |
493 if (card_is_verify(val)) | |
494 return true; | |
495 | |
496 if (card_is_clean(val)) | |
497 return false; | |
498 | |
499 if (card_is_dirty(val)) | |
500 return false; | |
501 | |
502 assert(false, "Found unhandled card mark type"); | |
503 | |
504 return false; | |
505 } | |
506 | |
507 // Assumes that only the base or the end changes. This allows indentification | |
508 // of the region that is being resized. The | |
509 // CardTableModRefBS::resize_covered_region() is used for the normal case | |
510 // where the covered regions are growing or shrinking at the high end. | |
511 // The method resize_covered_region_by_end() is analogous to | |
512 // CardTableModRefBS::resize_covered_region() but | |
513 // for regions that grow or shrink at the low end. | |
514 void CardTableExtension::resize_covered_region(MemRegion new_region) { | |
515 | |
516 for (int i = 0; i < _cur_covered_regions; i++) { | |
517 if (_covered[i].start() == new_region.start()) { | |
518 // Found a covered region with the same start as the | |
519 // new region. The region is growing or shrinking | |
520 // from the start of the region. | |
521 resize_covered_region_by_start(new_region); | |
522 return; | |
523 } | |
524 if (_covered[i].start() > new_region.start()) { | |
525 break; | |
526 } | |
527 } | |
528 | |
529 int changed_region = -1; | |
530 for (int j = 0; j < _cur_covered_regions; j++) { | |
531 if (_covered[j].end() == new_region.end()) { | |
532 changed_region = j; | |
533 // This is a case where the covered region is growing or shrinking | |
534 // at the start of the region. | |
535 assert(changed_region != -1, "Don't expect to add a covered region"); | |
536 assert(_covered[changed_region].byte_size() != new_region.byte_size(), | |
537 "The sizes should be different here"); | |
538 resize_covered_region_by_end(changed_region, new_region); | |
539 return; | |
540 } | |
541 } | |
542 // This should only be a new covered region (where no existing | |
543 // covered region matches at the start or the end). | |
544 assert(_cur_covered_regions < _max_covered_regions, | |
545 "An existing region should have been found"); | |
546 resize_covered_region_by_start(new_region); | |
547 } | |
548 | |
549 void CardTableExtension::resize_covered_region_by_start(MemRegion new_region) { | |
550 CardTableModRefBS::resize_covered_region(new_region); | |
551 debug_only(verify_guard();) | |
552 } | |
553 | |
554 void CardTableExtension::resize_covered_region_by_end(int changed_region, | |
555 MemRegion new_region) { | |
556 assert(SafepointSynchronize::is_at_safepoint(), | |
557 "Only expect an expansion at the low end at a GC"); | |
558 debug_only(verify_guard();) | |
559 #ifdef ASSERT | |
560 for (int k = 0; k < _cur_covered_regions; k++) { | |
561 if (_covered[k].end() == new_region.end()) { | |
562 assert(changed_region == k, "Changed region is incorrect"); | |
563 break; | |
564 } | |
565 } | |
566 #endif | |
567 | |
568 // Commit new or uncommit old pages, if necessary. | |
569 resize_commit_uncommit(changed_region, new_region); | |
570 | |
571 // Update card table entries | |
572 resize_update_card_table_entries(changed_region, new_region); | |
573 | |
574 // Set the new start of the committed region | |
575 resize_update_committed_table(changed_region, new_region); | |
576 | |
577 // Update the covered region | |
578 resize_update_covered_table(changed_region, new_region); | |
579 | |
580 if (TraceCardTableModRefBS) { | |
581 int ind = changed_region; | |
582 gclog_or_tty->print_cr("CardTableModRefBS::resize_covered_region: "); | |
583 gclog_or_tty->print_cr(" " | |
584 " _covered[%d].start(): " INTPTR_FORMAT | |
585 " _covered[%d].last(): " INTPTR_FORMAT, | |
586 ind, _covered[ind].start(), | |
587 ind, _covered[ind].last()); | |
588 gclog_or_tty->print_cr(" " | |
589 " _committed[%d].start(): " INTPTR_FORMAT | |
590 " _committed[%d].last(): " INTPTR_FORMAT, | |
591 ind, _committed[ind].start(), | |
592 ind, _committed[ind].last()); | |
593 gclog_or_tty->print_cr(" " | |
594 " byte_for(start): " INTPTR_FORMAT | |
595 " byte_for(last): " INTPTR_FORMAT, | |
596 byte_for(_covered[ind].start()), | |
597 byte_for(_covered[ind].last())); | |
598 gclog_or_tty->print_cr(" " | |
599 " addr_for(start): " INTPTR_FORMAT | |
600 " addr_for(last): " INTPTR_FORMAT, | |
601 addr_for((jbyte*) _committed[ind].start()), | |
602 addr_for((jbyte*) _committed[ind].last())); | |
603 } | |
604 debug_only(verify_guard();) | |
605 } | |
606 | |
607 void CardTableExtension::resize_commit_uncommit(int changed_region, | |
608 MemRegion new_region) { | |
609 // Commit new or uncommit old pages, if necessary. | |
610 MemRegion cur_committed = _committed[changed_region]; | |
611 assert(_covered[changed_region].end() == new_region.end(), | |
612 "The ends of the regions are expected to match"); | |
613 // Extend the start of this _committed region to | |
614 // to cover the start of any previous _committed region. | |
615 // This forms overlapping regions, but never interior regions. | |
616 HeapWord* min_prev_start = lowest_prev_committed_start(changed_region); | |
617 if (min_prev_start < cur_committed.start()) { | |
618 // Only really need to set start of "cur_committed" to | |
619 // the new start (min_prev_start) but assertion checking code | |
620 // below use cur_committed.end() so make it correct. | |
621 MemRegion new_committed = | |
622 MemRegion(min_prev_start, cur_committed.end()); | |
623 cur_committed = new_committed; | |
624 } | |
625 #ifdef ASSERT | |
626 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
627 assert(cur_committed.start() == | |
628 (HeapWord*) align_size_up((uintptr_t) cur_committed.start(), | |
629 os::vm_page_size()), | |
630 "Starts should have proper alignment"); | |
631 #endif | |
632 | |
633 jbyte* new_start = byte_for(new_region.start()); | |
634 // Round down because this is for the start address | |
635 HeapWord* new_start_aligned = | |
636 (HeapWord*)align_size_down((uintptr_t)new_start, os::vm_page_size()); | |
637 // The guard page is always committed and should not be committed over. | |
638 // This method is used in cases where the generation is growing toward | |
639 // lower addresses but the guard region is still at the end of the | |
640 // card table. That still makes sense when looking for writes | |
641 // off the end of the card table. | |
642 if (new_start_aligned < cur_committed.start()) { | |
643 // Expand the committed region | |
644 // | |
645 // Case A | |
646 // |+ guard +| | |
647 // |+ cur committed +++++++++| | |
648 // |+ new committed +++++++++++++++++| | |
649 // | |
650 // Case B | |
651 // |+ guard +| | |
652 // |+ cur committed +| | |
653 // |+ new committed +++++++| | |
654 // | |
655 // These are not expected because the calculation of the | |
656 // cur committed region and the new committed region | |
657 // share the same end for the covered region. | |
658 // Case C | |
659 // |+ guard +| | |
660 // |+ cur committed +| | |
661 // |+ new committed +++++++++++++++++| | |
662 // Case D | |
663 // |+ guard +| | |
664 // |+ cur committed +++++++++++| | |
665 // |+ new committed +++++++| | |
666 | |
667 HeapWord* new_end_for_commit = | |
668 MIN2(cur_committed.end(), _guard_region.start()); | |
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669 if(new_start_aligned < new_end_for_commit) { |
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670 MemRegion new_committed = |
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671 MemRegion(new_start_aligned, new_end_for_commit); |
0 | 672 if (!os::commit_memory((char*)new_committed.start(), |
673 new_committed.byte_size())) { | |
674 vm_exit_out_of_memory(new_committed.byte_size(), | |
675 "card table expansion"); | |
676 } | |
677 } | |
678 } else if (new_start_aligned > cur_committed.start()) { | |
679 // Shrink the committed region | |
680 MemRegion uncommit_region = committed_unique_to_self(changed_region, | |
681 MemRegion(cur_committed.start(), new_start_aligned)); | |
682 if (!uncommit_region.is_empty()) { | |
683 if (!os::uncommit_memory((char*)uncommit_region.start(), | |
684 uncommit_region.byte_size())) { | |
685 vm_exit_out_of_memory(uncommit_region.byte_size(), | |
686 "card table contraction"); | |
687 } | |
688 } | |
689 } | |
690 assert(_committed[changed_region].end() == cur_committed.end(), | |
691 "end should not change"); | |
692 } | |
693 | |
694 void CardTableExtension::resize_update_committed_table(int changed_region, | |
695 MemRegion new_region) { | |
696 | |
697 jbyte* new_start = byte_for(new_region.start()); | |
698 // Set the new start of the committed region | |
699 HeapWord* new_start_aligned = | |
700 (HeapWord*)align_size_down((uintptr_t)new_start, | |
701 os::vm_page_size()); | |
702 MemRegion new_committed = MemRegion(new_start_aligned, | |
703 _committed[changed_region].end()); | |
704 _committed[changed_region] = new_committed; | |
705 _committed[changed_region].set_start(new_start_aligned); | |
706 } | |
707 | |
708 void CardTableExtension::resize_update_card_table_entries(int changed_region, | |
709 MemRegion new_region) { | |
710 debug_only(verify_guard();) | |
711 MemRegion original_covered = _covered[changed_region]; | |
712 // Initialize the card entries. Only consider the | |
713 // region covered by the card table (_whole_heap) | |
714 jbyte* entry; | |
715 if (new_region.start() < _whole_heap.start()) { | |
716 entry = byte_for(_whole_heap.start()); | |
717 } else { | |
718 entry = byte_for(new_region.start()); | |
719 } | |
720 jbyte* end = byte_for(original_covered.start()); | |
721 // If _whole_heap starts at the original covered regions start, | |
722 // this loop will not execute. | |
723 while (entry < end) { *entry++ = clean_card; } | |
724 } | |
725 | |
726 void CardTableExtension::resize_update_covered_table(int changed_region, | |
727 MemRegion new_region) { | |
728 // Update the covered region | |
729 _covered[changed_region].set_start(new_region.start()); | |
730 _covered[changed_region].set_word_size(new_region.word_size()); | |
731 | |
732 // reorder regions. There should only be at most 1 out | |
733 // of order. | |
734 for (int i = _cur_covered_regions-1 ; i > 0; i--) { | |
735 if (_covered[i].start() < _covered[i-1].start()) { | |
736 MemRegion covered_mr = _covered[i-1]; | |
737 _covered[i-1] = _covered[i]; | |
738 _covered[i] = covered_mr; | |
739 MemRegion committed_mr = _committed[i-1]; | |
740 _committed[i-1] = _committed[i]; | |
741 _committed[i] = committed_mr; | |
742 break; | |
743 } | |
744 } | |
745 #ifdef ASSERT | |
746 for (int m = 0; m < _cur_covered_regions-1; m++) { | |
747 assert(_covered[m].start() <= _covered[m+1].start(), | |
748 "Covered regions out of order"); | |
749 assert(_committed[m].start() <= _committed[m+1].start(), | |
750 "Committed regions out of order"); | |
751 } | |
752 #endif | |
753 } | |
754 | |
755 // Returns the start of any committed region that is lower than | |
756 // the target committed region (index ind) and that intersects the | |
757 // target region. If none, return start of target region. | |
758 // | |
759 // ------------- | |
760 // | | | |
761 // ------------- | |
762 // ------------ | |
763 // | target | | |
764 // ------------ | |
765 // ------------- | |
766 // | | | |
767 // ------------- | |
768 // ^ returns this | |
769 // | |
770 // ------------- | |
771 // | | | |
772 // ------------- | |
773 // ------------ | |
774 // | target | | |
775 // ------------ | |
776 // ------------- | |
777 // | | | |
778 // ------------- | |
779 // ^ returns this | |
780 | |
781 HeapWord* CardTableExtension::lowest_prev_committed_start(int ind) const { | |
782 assert(_cur_covered_regions >= 0, "Expecting at least on region"); | |
783 HeapWord* min_start = _committed[ind].start(); | |
784 for (int j = 0; j < ind; j++) { | |
785 HeapWord* this_start = _committed[j].start(); | |
786 if ((this_start < min_start) && | |
787 !(_committed[j].intersection(_committed[ind])).is_empty()) { | |
788 min_start = this_start; | |
789 } | |
790 } | |
791 return min_start; | |
792 } |