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annotate src/share/vm/gc_implementation/parallelScavenge/cardTableExtension.cpp @ 1706:9d7a8ab3736b
6962589: remove breadth first scanning code from parallel gc
Summary: Remove the breadth-first copying order from ParallelScavenge and use depth-first by default.
Reviewed-by: jcoomes, ysr, johnc
| author | tonyp |
|---|---|
| date | Thu, 22 Jul 2010 10:27:41 -0400 |
| parents | fdde661c8e06 |
| children | f95d63e2154a |
| rev | line source |
|---|---|
| 0 | 1 /* |
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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 * | |
|
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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/_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 | |
| 127 if (sp->not_empty()) { | |
| 128 oop* sp_top = (oop*)space_top; | |
| 129 oop* prev_top = NULL; | |
| 130 jbyte* current_card = byte_for(sp->bottom()); | |
| 131 jbyte* end_card = byte_for(sp_top - 1); // sp_top is exclusive | |
| 132 // scan card marking array | |
| 133 while (current_card <= end_card) { | |
| 134 jbyte value = *current_card; | |
| 135 // skip clean cards | |
| 136 if (card_is_clean(value)) { | |
| 137 current_card++; | |
| 138 } else { | |
| 139 // we found a non-clean card | |
| 140 jbyte* first_nonclean_card = current_card++; | |
| 141 oop* bottom = (oop*)addr_for(first_nonclean_card); | |
| 142 // find object starting on card | |
| 143 oop* bottom_obj = (oop*)start_array->object_start((HeapWord*)bottom); | |
| 144 // bottom_obj = (oop*)start_array->object_start((HeapWord*)bottom); | |
| 145 assert(bottom_obj <= bottom, "just checking"); | |
| 146 // make sure we don't scan oops we already looked at | |
| 147 if (bottom < prev_top) bottom = prev_top; | |
| 148 // figure out when to stop scanning | |
| 149 jbyte* first_clean_card; | |
| 150 oop* top; | |
| 151 bool restart_scanning; | |
| 152 do { | |
| 153 restart_scanning = false; | |
| 154 // find a clean card | |
| 155 while (current_card <= end_card) { | |
| 156 value = *current_card; | |
| 157 if (card_is_clean(value)) break; | |
| 158 current_card++; | |
| 159 } | |
| 160 // check if we reached the end, if so we are done | |
| 161 if (current_card >= end_card) { | |
| 162 first_clean_card = end_card + 1; | |
| 163 current_card++; | |
| 164 top = sp_top; | |
| 165 } else { | |
| 166 // we have a clean card, find object starting on that card | |
| 167 first_clean_card = current_card++; | |
| 168 top = (oop*)addr_for(first_clean_card); | |
| 169 oop* top_obj = (oop*)start_array->object_start((HeapWord*)top); | |
| 170 // top_obj = (oop*)start_array->object_start((HeapWord*)top); | |
| 171 assert(top_obj <= top, "just checking"); | |
| 172 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) { | |
| 173 // an arrayOop is starting on the clean card - since we do exact store | |
| 174 // checks for objArrays we are done | |
| 175 } else { | |
| 176 // otherwise, it is possible that the object starting on the clean card | |
| 177 // spans the entire card, and that the store happened on a later card. | |
| 178 // figure out where the object ends | |
| 179 top = top_obj + oop(top_obj)->size(); | |
| 180 jbyte* top_card = CardTableModRefBS::byte_for(top - 1); // top is exclusive | |
| 181 if (top_card > first_clean_card) { | |
| 182 // object ends a different card | |
| 183 current_card = top_card + 1; | |
| 184 if (card_is_clean(*top_card)) { | |
| 185 // the ending card is clean, we are done | |
| 186 first_clean_card = top_card; | |
| 187 } else { | |
| 188 // the ending card is not clean, continue scanning at start of do-while | |
| 189 restart_scanning = true; | |
| 190 } | |
| 191 } else { | |
| 192 // object ends on the clean card, we are done. | |
| 193 assert(first_clean_card == top_card, "just checking"); | |
| 194 } | |
| 195 } | |
| 196 } | |
| 197 } while (restart_scanning); | |
| 198 // we know which cards to scan, now clear them | |
| 199 while (first_nonclean_card < first_clean_card) { | |
| 200 *first_nonclean_card++ = clean_card; | |
| 201 } | |
| 202 // scan oops in objects | |
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203 do { |
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204 oop(bottom_obj)->push_contents(pm); |
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205 bottom_obj += oop(bottom_obj)->size(); |
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206 assert(bottom_obj <= sp_top, "just checking"); |
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207 } while (bottom_obj < top); |
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208 pm->drain_stacks_cond_depth(); |
| 0 | 209 // remember top oop* scanned |
| 210 prev_top = top; | |
| 211 } | |
| 212 } | |
| 213 } | |
| 214 } | |
| 215 | |
| 216 void CardTableExtension::scavenge_contents_parallel(ObjectStartArray* start_array, | |
| 217 MutableSpace* sp, | |
| 218 HeapWord* space_top, | |
| 219 PSPromotionManager* pm, | |
| 220 uint stripe_number) { | |
| 221 int ssize = 128; // Naked constant! Work unit = 64k. | |
| 222 int dirty_card_count = 0; | |
| 223 | |
| 224 oop* sp_top = (oop*)space_top; | |
| 225 jbyte* start_card = byte_for(sp->bottom()); | |
| 226 jbyte* end_card = byte_for(sp_top - 1) + 1; | |
| 227 oop* last_scanned = NULL; // Prevent scanning objects more than once | |
| 228 for (jbyte* slice = start_card; slice < end_card; slice += ssize*ParallelGCThreads) { | |
| 229 jbyte* worker_start_card = slice + stripe_number * ssize; | |
| 230 if (worker_start_card >= end_card) | |
| 231 return; // We're done. | |
| 232 | |
| 233 jbyte* worker_end_card = worker_start_card + ssize; | |
| 234 if (worker_end_card > end_card) | |
| 235 worker_end_card = end_card; | |
| 236 | |
| 237 // We do not want to scan objects more than once. In order to accomplish | |
| 238 // this, we assert that any object with an object head inside our 'slice' | |
| 239 // belongs to us. We may need to extend the range of scanned cards if the | |
| 240 // last object continues into the next 'slice'. | |
| 241 // | |
| 242 // Note! ending cards are exclusive! | |
| 243 HeapWord* slice_start = addr_for(worker_start_card); | |
| 244 HeapWord* slice_end = MIN2((HeapWord*) sp_top, addr_for(worker_end_card)); | |
| 245 | |
| 246 // If there are not objects starting within the chunk, skip it. | |
| 247 if (!start_array->object_starts_in_range(slice_start, slice_end)) { | |
| 248 continue; | |
| 249 } | |
| 605 | 250 // Update our beginning addr |
| 0 | 251 HeapWord* first_object = start_array->object_start(slice_start); |
| 252 debug_only(oop* first_object_within_slice = (oop*) first_object;) | |
| 253 if (first_object < slice_start) { | |
| 254 last_scanned = (oop*)(first_object + oop(first_object)->size()); | |
| 255 debug_only(first_object_within_slice = last_scanned;) | |
| 256 worker_start_card = byte_for(last_scanned); | |
| 257 } | |
| 258 | |
| 259 // Update the ending addr | |
| 260 if (slice_end < (HeapWord*)sp_top) { | |
| 261 // The subtraction is important! An object may start precisely at slice_end. | |
| 262 HeapWord* last_object = start_array->object_start(slice_end - 1); | |
| 263 slice_end = last_object + oop(last_object)->size(); | |
| 264 // worker_end_card is exclusive, so bump it one past the end of last_object's | |
| 265 // covered span. | |
| 266 worker_end_card = byte_for(slice_end) + 1; | |
| 267 | |
| 268 if (worker_end_card > end_card) | |
| 269 worker_end_card = end_card; | |
| 270 } | |
| 271 | |
| 272 assert(slice_end <= (HeapWord*)sp_top, "Last object in slice crosses space boundary"); | |
| 273 assert(is_valid_card_address(worker_start_card), "Invalid worker start card"); | |
| 274 assert(is_valid_card_address(worker_end_card), "Invalid worker end card"); | |
| 275 // Note that worker_start_card >= worker_end_card is legal, and happens when | |
| 276 // an object spans an entire slice. | |
| 277 assert(worker_start_card <= end_card, "worker start card beyond end card"); | |
| 278 assert(worker_end_card <= end_card, "worker end card beyond end card"); | |
| 279 | |
| 280 jbyte* current_card = worker_start_card; | |
| 281 while (current_card < worker_end_card) { | |
| 282 // Find an unclean card. | |
| 283 while (current_card < worker_end_card && card_is_clean(*current_card)) { | |
| 284 current_card++; | |
| 285 } | |
| 286 jbyte* first_unclean_card = current_card; | |
| 287 | |
| 288 // Find the end of a run of contiguous unclean cards | |
| 289 while (current_card < worker_end_card && !card_is_clean(*current_card)) { | |
| 290 while (current_card < worker_end_card && !card_is_clean(*current_card)) { | |
| 291 current_card++; | |
| 292 } | |
| 293 | |
| 294 if (current_card < worker_end_card) { | |
| 295 // Some objects may be large enough to span several cards. If such | |
| 296 // an object has more than one dirty card, separated by a clean card, | |
| 297 // we will attempt to scan it twice. The test against "last_scanned" | |
| 298 // prevents the redundant object scan, but it does not prevent newly | |
| 299 // marked cards from being cleaned. | |
| 300 HeapWord* last_object_in_dirty_region = start_array->object_start(addr_for(current_card)-1); | |
| 301 size_t size_of_last_object = oop(last_object_in_dirty_region)->size(); | |
| 302 HeapWord* end_of_last_object = last_object_in_dirty_region + size_of_last_object; | |
| 303 jbyte* ending_card_of_last_object = byte_for(end_of_last_object); | |
| 304 assert(ending_card_of_last_object <= worker_end_card, "ending_card_of_last_object is greater than worker_end_card"); | |
| 305 if (ending_card_of_last_object > current_card) { | |
| 306 // This means the object spans the next complete card. | |
| 307 // We need to bump the current_card to ending_card_of_last_object | |
| 308 current_card = ending_card_of_last_object; | |
| 309 } | |
| 310 } | |
| 311 } | |
| 312 jbyte* following_clean_card = current_card; | |
| 313 | |
| 314 if (first_unclean_card < worker_end_card) { | |
| 315 oop* p = (oop*) start_array->object_start(addr_for(first_unclean_card)); | |
| 316 assert((HeapWord*)p <= addr_for(first_unclean_card), "checking"); | |
| 317 // "p" should always be >= "last_scanned" because newly GC dirtied | |
| 318 // cards are no longer scanned again (see comment at end | |
| 319 // of loop on the increment of "current_card"). Test that | |
| 320 // hypothesis before removing this code. | |
| 321 // If this code is removed, deal with the first time through | |
| 322 // the loop when the last_scanned is the object starting in | |
| 323 // the previous slice. | |
| 324 assert((p >= last_scanned) || | |
| 325 (last_scanned == first_object_within_slice), | |
| 326 "Should no longer be possible"); | |
| 327 if (p < last_scanned) { | |
| 328 // Avoid scanning more than once; this can happen because | |
| 329 // newgen cards set by GC may a different set than the | |
| 330 // originally dirty set | |
| 331 p = last_scanned; | |
| 332 } | |
| 333 oop* to = (oop*)addr_for(following_clean_card); | |
| 334 | |
| 335 // Test slice_end first! | |
| 336 if ((HeapWord*)to > slice_end) { | |
| 337 to = (oop*)slice_end; | |
| 338 } else if (to > sp_top) { | |
| 339 to = sp_top; | |
| 340 } | |
| 341 | |
| 342 // we know which cards to scan, now clear them | |
| 343 if (first_unclean_card <= worker_start_card+1) | |
| 344 first_unclean_card = worker_start_card+1; | |
| 345 if (following_clean_card >= worker_end_card-1) | |
| 346 following_clean_card = worker_end_card-1; | |
| 347 | |
| 348 while (first_unclean_card < following_clean_card) { | |
| 349 *first_unclean_card++ = clean_card; | |
| 350 } | |
| 351 | |
| 352 const int interval = PrefetchScanIntervalInBytes; | |
| 353 // scan all objects in the range | |
| 354 if (interval != 0) { | |
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355 while (p < to) { |
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356 Prefetch::write(p, interval); |
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357 oop m = oop(p); |
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358 assert(m->is_oop_or_null(), "check for header"); |
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359 m->push_contents(pm); |
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360 p += m->size(); |
| 0 | 361 } |
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362 pm->drain_stacks_cond_depth(); |
| 0 | 363 } else { |
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364 while (p < to) { |
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365 oop m = oop(p); |
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366 assert(m->is_oop_or_null(), "check for header"); |
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367 m->push_contents(pm); |
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368 p += m->size(); |
| 0 | 369 } |
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370 pm->drain_stacks_cond_depth(); |
| 0 | 371 } |
| 372 last_scanned = p; | |
| 373 } | |
| 374 // "current_card" is still the "following_clean_card" or | |
| 375 // the current_card is >= the worker_end_card so the | |
| 376 // loop will not execute again. | |
| 377 assert((current_card == following_clean_card) || | |
| 378 (current_card >= worker_end_card), | |
| 379 "current_card should only be incremented if it still equals " | |
| 380 "following_clean_card"); | |
| 381 // Increment current_card so that it is not processed again. | |
| 382 // It may now be dirty because a old-to-young pointer was | |
| 383 // found on it an updated. If it is now dirty, it cannot be | |
| 384 // be safely cleaned in the next iteration. | |
| 385 current_card++; | |
| 386 } | |
| 387 } | |
| 388 } | |
| 389 | |
| 390 // This should be called before a scavenge. | |
| 391 void CardTableExtension::verify_all_young_refs_imprecise() { | |
| 392 CheckForUnmarkedObjects check; | |
| 393 | |
| 394 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
| 395 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
| 396 | |
| 397 PSOldGen* old_gen = heap->old_gen(); | |
| 398 PSPermGen* perm_gen = heap->perm_gen(); | |
| 399 | |
| 400 old_gen->object_iterate(&check); | |
| 401 perm_gen->object_iterate(&check); | |
| 402 } | |
| 403 | |
| 404 // This should be called immediately after a scavenge, before mutators resume. | |
| 405 void CardTableExtension::verify_all_young_refs_precise() { | |
| 406 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
| 407 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); | |
| 408 | |
| 409 PSOldGen* old_gen = heap->old_gen(); | |
| 410 PSPermGen* perm_gen = heap->perm_gen(); | |
| 411 | |
| 412 CheckForPreciseMarks check(heap->young_gen(), (CardTableExtension*)heap->barrier_set()); | |
| 413 | |
| 414 old_gen->oop_iterate(&check); | |
| 415 perm_gen->oop_iterate(&check); | |
| 416 | |
| 417 verify_all_young_refs_precise_helper(old_gen->object_space()->used_region()); | |
| 418 verify_all_young_refs_precise_helper(perm_gen->object_space()->used_region()); | |
| 419 } | |
| 420 | |
| 421 void CardTableExtension::verify_all_young_refs_precise_helper(MemRegion mr) { | |
| 422 CardTableExtension* card_table = (CardTableExtension*)Universe::heap()->barrier_set(); | |
| 423 // FIX ME ASSERT HERE | |
| 424 | |
| 425 jbyte* bot = card_table->byte_for(mr.start()); | |
| 426 jbyte* top = card_table->byte_for(mr.end()); | |
| 427 while(bot <= top) { | |
| 428 assert(*bot == clean_card || *bot == verify_card, "Found unwanted or unknown card mark"); | |
| 429 if (*bot == verify_card) | |
| 430 *bot = youngergen_card; | |
| 431 bot++; | |
| 432 } | |
| 433 } | |
| 434 | |
| 435 bool CardTableExtension::addr_is_marked_imprecise(void *addr) { | |
| 436 jbyte* p = byte_for(addr); | |
| 437 jbyte val = *p; | |
| 438 | |
| 439 if (card_is_dirty(val)) | |
| 440 return true; | |
| 441 | |
| 442 if (card_is_newgen(val)) | |
| 443 return true; | |
| 444 | |
| 445 if (card_is_clean(val)) | |
| 446 return false; | |
| 447 | |
| 448 assert(false, "Found unhandled card mark type"); | |
| 449 | |
| 450 return false; | |
| 451 } | |
| 452 | |
| 453 // Also includes verify_card | |
| 454 bool CardTableExtension::addr_is_marked_precise(void *addr) { | |
| 455 jbyte* p = byte_for(addr); | |
| 456 jbyte val = *p; | |
| 457 | |
| 458 if (card_is_newgen(val)) | |
| 459 return true; | |
| 460 | |
| 461 if (card_is_verify(val)) | |
| 462 return true; | |
| 463 | |
| 464 if (card_is_clean(val)) | |
| 465 return false; | |
| 466 | |
| 467 if (card_is_dirty(val)) | |
| 468 return false; | |
| 469 | |
| 470 assert(false, "Found unhandled card mark type"); | |
| 471 | |
| 472 return false; | |
| 473 } | |
| 474 | |
| 475 // Assumes that only the base or the end changes. This allows indentification | |
| 476 // of the region that is being resized. The | |
| 477 // CardTableModRefBS::resize_covered_region() is used for the normal case | |
| 478 // where the covered regions are growing or shrinking at the high end. | |
| 479 // The method resize_covered_region_by_end() is analogous to | |
| 480 // CardTableModRefBS::resize_covered_region() but | |
| 481 // for regions that grow or shrink at the low end. | |
| 482 void CardTableExtension::resize_covered_region(MemRegion new_region) { | |
| 483 | |
| 484 for (int i = 0; i < _cur_covered_regions; i++) { | |
| 485 if (_covered[i].start() == new_region.start()) { | |
| 486 // Found a covered region with the same start as the | |
| 487 // new region. The region is growing or shrinking | |
| 488 // from the start of the region. | |
| 489 resize_covered_region_by_start(new_region); | |
| 490 return; | |
| 491 } | |
| 492 if (_covered[i].start() > new_region.start()) { | |
| 493 break; | |
| 494 } | |
| 495 } | |
| 496 | |
| 497 int changed_region = -1; | |
| 498 for (int j = 0; j < _cur_covered_regions; j++) { | |
| 499 if (_covered[j].end() == new_region.end()) { | |
| 500 changed_region = j; | |
| 501 // This is a case where the covered region is growing or shrinking | |
| 502 // at the start of the region. | |
| 503 assert(changed_region != -1, "Don't expect to add a covered region"); | |
| 504 assert(_covered[changed_region].byte_size() != new_region.byte_size(), | |
| 505 "The sizes should be different here"); | |
| 506 resize_covered_region_by_end(changed_region, new_region); | |
| 507 return; | |
| 508 } | |
| 509 } | |
| 510 // This should only be a new covered region (where no existing | |
| 511 // covered region matches at the start or the end). | |
| 512 assert(_cur_covered_regions < _max_covered_regions, | |
| 513 "An existing region should have been found"); | |
| 514 resize_covered_region_by_start(new_region); | |
| 515 } | |
| 516 | |
| 517 void CardTableExtension::resize_covered_region_by_start(MemRegion new_region) { | |
| 518 CardTableModRefBS::resize_covered_region(new_region); | |
| 519 debug_only(verify_guard();) | |
| 520 } | |
| 521 | |
| 522 void CardTableExtension::resize_covered_region_by_end(int changed_region, | |
| 523 MemRegion new_region) { | |
| 524 assert(SafepointSynchronize::is_at_safepoint(), | |
| 525 "Only expect an expansion at the low end at a GC"); | |
| 526 debug_only(verify_guard();) | |
| 527 #ifdef ASSERT | |
| 528 for (int k = 0; k < _cur_covered_regions; k++) { | |
| 529 if (_covered[k].end() == new_region.end()) { | |
| 530 assert(changed_region == k, "Changed region is incorrect"); | |
| 531 break; | |
| 532 } | |
| 533 } | |
| 534 #endif | |
| 535 | |
| 536 // Commit new or uncommit old pages, if necessary. | |
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537 if (resize_commit_uncommit(changed_region, new_region)) { |
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538 // Set the new start of the committed region |
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539 resize_update_committed_table(changed_region, new_region); |
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540 } |
| 0 | 541 |
| 542 // Update card table entries | |
| 543 resize_update_card_table_entries(changed_region, new_region); | |
| 544 | |
| 545 // Update the covered region | |
| 546 resize_update_covered_table(changed_region, new_region); | |
| 547 | |
| 548 if (TraceCardTableModRefBS) { | |
| 549 int ind = changed_region; | |
| 550 gclog_or_tty->print_cr("CardTableModRefBS::resize_covered_region: "); | |
| 551 gclog_or_tty->print_cr(" " | |
| 552 " _covered[%d].start(): " INTPTR_FORMAT | |
| 553 " _covered[%d].last(): " INTPTR_FORMAT, | |
| 554 ind, _covered[ind].start(), | |
| 555 ind, _covered[ind].last()); | |
| 556 gclog_or_tty->print_cr(" " | |
| 557 " _committed[%d].start(): " INTPTR_FORMAT | |
| 558 " _committed[%d].last(): " INTPTR_FORMAT, | |
| 559 ind, _committed[ind].start(), | |
| 560 ind, _committed[ind].last()); | |
| 561 gclog_or_tty->print_cr(" " | |
| 562 " byte_for(start): " INTPTR_FORMAT | |
| 563 " byte_for(last): " INTPTR_FORMAT, | |
| 564 byte_for(_covered[ind].start()), | |
| 565 byte_for(_covered[ind].last())); | |
| 566 gclog_or_tty->print_cr(" " | |
| 567 " addr_for(start): " INTPTR_FORMAT | |
| 568 " addr_for(last): " INTPTR_FORMAT, | |
| 569 addr_for((jbyte*) _committed[ind].start()), | |
| 570 addr_for((jbyte*) _committed[ind].last())); | |
| 571 } | |
| 572 debug_only(verify_guard();) | |
| 573 } | |
| 574 | |
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575 bool CardTableExtension::resize_commit_uncommit(int changed_region, |
| 0 | 576 MemRegion new_region) { |
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577 bool result = false; |
| 0 | 578 // Commit new or uncommit old pages, if necessary. |
| 579 MemRegion cur_committed = _committed[changed_region]; | |
| 580 assert(_covered[changed_region].end() == new_region.end(), | |
| 581 "The ends of the regions are expected to match"); | |
| 582 // Extend the start of this _committed region to | |
| 583 // to cover the start of any previous _committed region. | |
| 584 // This forms overlapping regions, but never interior regions. | |
| 585 HeapWord* min_prev_start = lowest_prev_committed_start(changed_region); | |
| 586 if (min_prev_start < cur_committed.start()) { | |
| 587 // Only really need to set start of "cur_committed" to | |
| 588 // the new start (min_prev_start) but assertion checking code | |
| 589 // below use cur_committed.end() so make it correct. | |
| 590 MemRegion new_committed = | |
| 591 MemRegion(min_prev_start, cur_committed.end()); | |
| 592 cur_committed = new_committed; | |
| 593 } | |
| 594 #ifdef ASSERT | |
| 595 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); | |
| 596 assert(cur_committed.start() == | |
| 597 (HeapWord*) align_size_up((uintptr_t) cur_committed.start(), | |
| 598 os::vm_page_size()), | |
| 599 "Starts should have proper alignment"); | |
| 600 #endif | |
| 601 | |
| 602 jbyte* new_start = byte_for(new_region.start()); | |
| 603 // Round down because this is for the start address | |
| 604 HeapWord* new_start_aligned = | |
| 605 (HeapWord*)align_size_down((uintptr_t)new_start, os::vm_page_size()); | |
| 606 // The guard page is always committed and should not be committed over. | |
| 607 // This method is used in cases where the generation is growing toward | |
| 608 // lower addresses but the guard region is still at the end of the | |
| 609 // card table. That still makes sense when looking for writes | |
| 610 // off the end of the card table. | |
| 611 if (new_start_aligned < cur_committed.start()) { | |
| 612 // Expand the committed region | |
| 613 // | |
| 614 // Case A | |
| 615 // |+ guard +| | |
| 616 // |+ cur committed +++++++++| | |
| 617 // |+ new committed +++++++++++++++++| | |
| 618 // | |
| 619 // Case B | |
| 620 // |+ guard +| | |
| 621 // |+ cur committed +| | |
| 622 // |+ new committed +++++++| | |
| 623 // | |
| 624 // These are not expected because the calculation of the | |
| 625 // cur committed region and the new committed region | |
| 626 // share the same end for the covered region. | |
| 627 // Case C | |
| 628 // |+ guard +| | |
| 629 // |+ cur committed +| | |
| 630 // |+ new committed +++++++++++++++++| | |
| 631 // Case D | |
| 632 // |+ guard +| | |
| 633 // |+ cur committed +++++++++++| | |
| 634 // |+ new committed +++++++| | |
| 635 | |
| 636 HeapWord* new_end_for_commit = | |
| 637 MIN2(cur_committed.end(), _guard_region.start()); | |
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638 if(new_start_aligned < new_end_for_commit) { |
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639 MemRegion new_committed = |
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640 MemRegion(new_start_aligned, new_end_for_commit); |
| 0 | 641 if (!os::commit_memory((char*)new_committed.start(), |
| 642 new_committed.byte_size())) { | |
| 643 vm_exit_out_of_memory(new_committed.byte_size(), | |
| 644 "card table expansion"); | |
| 645 } | |
| 646 } | |
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647 result = true; |
| 0 | 648 } else if (new_start_aligned > cur_committed.start()) { |
| 649 // Shrink the committed region | |
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650 #if 0 // uncommitting space is currently unsafe because of the interactions |
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651 // of growing and shrinking regions. One region A can uncommit space |
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652 // that it owns but which is being used by another region B (maybe). |
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653 // Region B has not committed the space because it was already |
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654 // committed by region A. |
| 0 | 655 MemRegion uncommit_region = committed_unique_to_self(changed_region, |
| 656 MemRegion(cur_committed.start(), new_start_aligned)); | |
| 657 if (!uncommit_region.is_empty()) { | |
| 658 if (!os::uncommit_memory((char*)uncommit_region.start(), | |
| 659 uncommit_region.byte_size())) { | |
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660 // If the uncommit fails, ignore it. Let the |
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661 // committed table resizing go even though the committed |
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662 // table will over state the committed space. |
| 0 | 663 } |
| 664 } | |
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665 #else |
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666 assert(!result, "Should be false with current workaround"); |
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667 #endif |
| 0 | 668 } |
| 669 assert(_committed[changed_region].end() == cur_committed.end(), | |
| 670 "end should not change"); | |
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671 return result; |
| 0 | 672 } |
| 673 | |
| 674 void CardTableExtension::resize_update_committed_table(int changed_region, | |
| 675 MemRegion new_region) { | |
| 676 | |
| 677 jbyte* new_start = byte_for(new_region.start()); | |
| 678 // Set the new start of the committed region | |
| 679 HeapWord* new_start_aligned = | |
| 680 (HeapWord*)align_size_down((uintptr_t)new_start, | |
| 681 os::vm_page_size()); | |
| 682 MemRegion new_committed = MemRegion(new_start_aligned, | |
| 683 _committed[changed_region].end()); | |
| 684 _committed[changed_region] = new_committed; | |
| 685 _committed[changed_region].set_start(new_start_aligned); | |
| 686 } | |
| 687 | |
| 688 void CardTableExtension::resize_update_card_table_entries(int changed_region, | |
| 689 MemRegion new_region) { | |
| 690 debug_only(verify_guard();) | |
| 691 MemRegion original_covered = _covered[changed_region]; | |
| 692 // Initialize the card entries. Only consider the | |
| 693 // region covered by the card table (_whole_heap) | |
| 694 jbyte* entry; | |
| 695 if (new_region.start() < _whole_heap.start()) { | |
| 696 entry = byte_for(_whole_heap.start()); | |
| 697 } else { | |
| 698 entry = byte_for(new_region.start()); | |
| 699 } | |
| 700 jbyte* end = byte_for(original_covered.start()); | |
| 701 // If _whole_heap starts at the original covered regions start, | |
| 702 // this loop will not execute. | |
| 703 while (entry < end) { *entry++ = clean_card; } | |
| 704 } | |
| 705 | |
| 706 void CardTableExtension::resize_update_covered_table(int changed_region, | |
| 707 MemRegion new_region) { | |
| 708 // Update the covered region | |
| 709 _covered[changed_region].set_start(new_region.start()); | |
| 710 _covered[changed_region].set_word_size(new_region.word_size()); | |
| 711 | |
| 712 // reorder regions. There should only be at most 1 out | |
| 713 // of order. | |
| 714 for (int i = _cur_covered_regions-1 ; i > 0; i--) { | |
| 715 if (_covered[i].start() < _covered[i-1].start()) { | |
| 716 MemRegion covered_mr = _covered[i-1]; | |
| 717 _covered[i-1] = _covered[i]; | |
| 718 _covered[i] = covered_mr; | |
| 719 MemRegion committed_mr = _committed[i-1]; | |
| 720 _committed[i-1] = _committed[i]; | |
| 721 _committed[i] = committed_mr; | |
| 722 break; | |
| 723 } | |
| 724 } | |
| 725 #ifdef ASSERT | |
| 726 for (int m = 0; m < _cur_covered_regions-1; m++) { | |
| 727 assert(_covered[m].start() <= _covered[m+1].start(), | |
| 728 "Covered regions out of order"); | |
| 729 assert(_committed[m].start() <= _committed[m+1].start(), | |
| 730 "Committed regions out of order"); | |
| 731 } | |
| 732 #endif | |
| 733 } | |
| 734 | |
| 735 // Returns the start of any committed region that is lower than | |
| 736 // the target committed region (index ind) and that intersects the | |
| 737 // target region. If none, return start of target region. | |
| 738 // | |
| 739 // ------------- | |
| 740 // | | | |
| 741 // ------------- | |
| 742 // ------------ | |
| 743 // | target | | |
| 744 // ------------ | |
| 745 // ------------- | |
| 746 // | | | |
| 747 // ------------- | |
| 748 // ^ returns this | |
| 749 // | |
| 750 // ------------- | |
| 751 // | | | |
| 752 // ------------- | |
| 753 // ------------ | |
| 754 // | target | | |
| 755 // ------------ | |
| 756 // ------------- | |
| 757 // | | | |
| 758 // ------------- | |
| 759 // ^ returns this | |
| 760 | |
| 761 HeapWord* CardTableExtension::lowest_prev_committed_start(int ind) const { | |
| 762 assert(_cur_covered_regions >= 0, "Expecting at least on region"); | |
| 763 HeapWord* min_start = _committed[ind].start(); | |
| 764 for (int j = 0; j < ind; j++) { | |
| 765 HeapWord* this_start = _committed[j].start(); | |
| 766 if ((this_start < min_start) && | |
| 767 !(_committed[j].intersection(_committed[ind])).is_empty()) { | |
| 768 min_start = this_start; | |
| 769 } | |
| 770 } | |
| 771 return min_start; | |
| 772 } |