1 /* 2 * Copyright (c) 2011, 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 27 #include "gc_implementation/g1/heapRegionRemSet.hpp" 28 #include "gc_implementation/g1/heapRegionSet.inline.hpp" 29 30 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 31 32 uint FreeRegionList::_unrealistically_long_length = 0; 33 34 void HeapRegionSetBase::fill_in_ext_msg(hrs_ext_msg* msg, const char* message) { 35 msg->append("[%s] %s ln: %u cy: "SIZE_FORMAT, 36 name(), message, length(), total_capacity_bytes()); 37 fill_in_ext_msg_extra(msg); 38 } 39 40 #ifndef PRODUCT 41 void HeapRegionSetBase::verify_region(HeapRegion* hr) { 42 assert(hr->containing_set() == this, err_msg("Inconsistent containing set for %u", hr->hrm_index())); 43 assert(!hr->is_young(), err_msg("Adding young region %u", hr->hrm_index())); // currently we don't use these sets for young regions 44 assert(hr->is_humongous() == regions_humongous(), err_msg("Wrong humongous state for region %u and set %s", hr->hrm_index(), name())); 45 assert(hr->is_free() == regions_free(), err_msg("Wrong free state for region %u and set %s", hr->hrm_index(), name())); 46 assert(!hr->is_free() || hr->is_empty(), err_msg("Free region %u is not empty for set %s", hr->hrm_index(), name())); 47 assert(!hr->is_empty() || hr->is_free(), err_msg("Empty region %u is not free for set %s", hr->hrm_index(), name())); 48 assert(hr->rem_set()->verify_ready_for_par_iteration(), err_msg("Wrong iteration state %u", hr->hrm_index())); 49 } 50 #endif 51 52 void HeapRegionSetBase::verify() { 53 // It's important that we also observe the MT safety protocol even 54 // for the verification calls. If we do verification without the 55 // appropriate locks and the set changes underneath our feet 56 // verification might fail and send us on a wild goose chase. 57 check_mt_safety(); 58 59 guarantee(( is_empty() && length() == 0 && total_capacity_bytes() == 0) || 60 (!is_empty() && length() >= 0 && total_capacity_bytes() >= 0), 61 hrs_ext_msg(this, "invariant")); 62 } 63 64 void HeapRegionSetBase::verify_start() { 65 // See comment in verify() about MT safety and verification. 66 check_mt_safety(); 67 assert(!_verify_in_progress, 68 hrs_ext_msg(this, "verification should not be in progress")); 69 70 // Do the basic verification first before we do the checks over the regions. 71 HeapRegionSetBase::verify(); 72 73 _verify_in_progress = true; 74 } 75 76 void HeapRegionSetBase::verify_end() { 77 // See comment in verify() about MT safety and verification. 78 check_mt_safety(); 79 assert(_verify_in_progress, 80 hrs_ext_msg(this, "verification should be in progress")); 81 82 _verify_in_progress = false; 83 } 84 85 void HeapRegionSetBase::print_on(outputStream* out, bool print_contents) { 86 out->cr(); 87 out->print_cr("Set: %s ("PTR_FORMAT")", name(), this); 88 out->print_cr(" Region Assumptions"); 89 out->print_cr(" humongous : %s", BOOL_TO_STR(regions_humongous())); 90 out->print_cr(" free : %s", BOOL_TO_STR(regions_free())); 91 out->print_cr(" Attributes"); 92 out->print_cr(" length : %14u", length()); 93 out->print_cr(" total capacity : "SIZE_FORMAT_W(14)" bytes", 94 total_capacity_bytes()); 95 } 96 97 HeapRegionSetBase::HeapRegionSetBase(const char* name, bool humongous, bool free, HRSMtSafeChecker* mt_safety_checker) 98 : _name(name), _verify_in_progress(false), 99 _is_humongous(humongous), _is_free(free), _mt_safety_checker(mt_safety_checker), 100 _count() 101 { } 102 103 void FreeRegionList::set_unrealistically_long_length(uint len) { 104 guarantee(_unrealistically_long_length == 0, "should only be set once"); 105 _unrealistically_long_length = len; 106 } 107 108 void FreeRegionList::fill_in_ext_msg_extra(hrs_ext_msg* msg) { 109 msg->append(" hd: "PTR_FORMAT" tl: "PTR_FORMAT, _head, _tail); 110 } 111 112 void FreeRegionList::remove_all() { 113 check_mt_safety(); 114 verify_optional(); 115 116 HeapRegion* curr = _head; 117 while (curr != NULL) { 118 verify_region(curr); 119 120 HeapRegion* next = curr->next(); 121 curr->set_next(NULL); 122 curr->set_prev(NULL); 123 curr->set_containing_set(NULL); 124 curr = next; 125 } 126 clear(); 127 128 verify_optional(); 129 } 130 131 void FreeRegionList::add_ordered(FreeRegionList* from_list) { 132 check_mt_safety(); 133 from_list->check_mt_safety(); 134 135 verify_optional(); 136 from_list->verify_optional(); 137 138 if (from_list->is_empty()) { 139 return; 140 } 141 142 #ifdef ASSERT 143 FreeRegionListIterator iter(from_list); 144 while (iter.more_available()) { 145 HeapRegion* hr = iter.get_next(); 146 // In set_containing_set() we check that we either set the value 147 // from NULL to non-NULL or vice versa to catch bugs. So, we have 148 // to NULL it first before setting it to the value. 149 hr->set_containing_set(NULL); 150 hr->set_containing_set(this); 151 } 152 #endif // ASSERT 153 154 if (is_empty()) { 155 assert(length() == 0 && _tail == NULL, hrs_ext_msg(this, "invariant")); 156 _head = from_list->_head; 157 _tail = from_list->_tail; 158 } else { 159 HeapRegion* curr_to = _head; 160 HeapRegion* curr_from = from_list->_head; 161 162 while (curr_from != NULL) { 163 while (curr_to != NULL && curr_to->hrm_index() < curr_from->hrm_index()) { 164 curr_to = curr_to->next(); 165 } 166 167 if (curr_to == NULL) { 168 // The rest of the from list should be added as tail 169 _tail->set_next(curr_from); 170 curr_from->set_prev(_tail); 171 curr_from = NULL; 172 } else { 173 HeapRegion* next_from = curr_from->next(); 174 175 curr_from->set_next(curr_to); 176 curr_from->set_prev(curr_to->prev()); 177 if (curr_to->prev() == NULL) { 178 _head = curr_from; 179 } else { 180 curr_to->prev()->set_next(curr_from); 181 } 182 curr_to->set_prev(curr_from); 183 184 curr_from = next_from; 185 } 186 } 187 188 if (_tail->hrm_index() < from_list->_tail->hrm_index()) { 189 _tail = from_list->_tail; 190 } 191 } 192 193 _count.increment(from_list->length(), from_list->total_capacity_bytes()); 194 from_list->clear(); 195 196 verify_optional(); 197 from_list->verify_optional(); 198 } 199 200 void FreeRegionList::remove_starting_at(HeapRegion* first, uint num_regions) { 201 check_mt_safety(); 202 assert(num_regions >= 1, hrs_ext_msg(this, "pre-condition")); 203 assert(!is_empty(), hrs_ext_msg(this, "pre-condition")); 204 205 verify_optional(); 206 DEBUG_ONLY(uint old_length = length();) 207 208 HeapRegion* curr = first; 209 uint count = 0; 210 while (count < num_regions) { 211 verify_region(curr); 212 HeapRegion* next = curr->next(); 213 HeapRegion* prev = curr->prev(); 214 215 assert(count < num_regions, 216 hrs_err_msg("[%s] should not come across more regions " 217 "pending for removal than num_regions: %u", 218 name(), num_regions)); 219 220 if (prev == NULL) { 221 assert(_head == curr, hrs_ext_msg(this, "invariant")); 222 _head = next; 223 } else { 224 assert(_head != curr, hrs_ext_msg(this, "invariant")); 225 prev->set_next(next); 226 } 227 if (next == NULL) { 228 assert(_tail == curr, hrs_ext_msg(this, "invariant")); 229 _tail = prev; 230 } else { 231 assert(_tail != curr, hrs_ext_msg(this, "invariant")); 232 next->set_prev(prev); 233 } 234 if (_last = curr) { 235 _last = NULL; 236 } 237 238 curr->set_next(NULL); 239 curr->set_prev(NULL); 240 remove(curr); 241 242 count++; 243 curr = next; 244 } 245 246 assert(count == num_regions, 247 hrs_err_msg("[%s] count: %u should be == num_regions: %u", 248 name(), count, num_regions)); 249 assert(length() + num_regions == old_length, 250 hrs_err_msg("[%s] new length should be consistent " 251 "new length: %u old length: %u num_regions: %u", 252 name(), length(), old_length, num_regions)); 253 254 verify_optional(); 255 } 256 257 void FreeRegionList::verify() { 258 // See comment in HeapRegionSetBase::verify() about MT safety and 259 // verification. 260 check_mt_safety(); 261 262 // This will also do the basic verification too. 263 verify_start(); 264 265 verify_list(); 266 267 verify_end(); 268 } 269 270 void FreeRegionList::clear() { 271 _count = HeapRegionSetCount(); 272 _head = NULL; 273 _tail = NULL; 274 _last = NULL; 275 } 276 277 void FreeRegionList::print_on(outputStream* out, bool print_contents) { 278 HeapRegionSetBase::print_on(out, print_contents); 279 out->print_cr(" Linking"); 280 out->print_cr(" head : "PTR_FORMAT, _head); 281 out->print_cr(" tail : "PTR_FORMAT, _tail); 282 283 if (print_contents) { 284 out->print_cr(" Contents"); 285 FreeRegionListIterator iter(this); 286 while (iter.more_available()) { 287 HeapRegion* hr = iter.get_next(); 288 hr->print_on(out); 289 } 290 } 291 292 out->cr(); 293 } 294 295 void FreeRegionList::verify_list() { 296 HeapRegion* curr = _head; 297 HeapRegion* prev1 = NULL; 298 HeapRegion* prev0 = NULL; 299 uint count = 0; 300 size_t capacity = 0; 301 uint last_index = 0; 302 303 guarantee(_head == NULL || _head->prev() == NULL, "_head should not have a prev"); 304 while (curr != NULL) { 305 verify_region(curr); 306 307 count++; 308 guarantee(count < _unrealistically_long_length, 309 hrs_err_msg("[%s] the calculated length: %u seems very long, is there maybe a cycle? curr: "PTR_FORMAT" prev0: "PTR_FORMAT" " "prev1: "PTR_FORMAT" length: %u", name(), count, curr, prev0, prev1, length())); 310 311 if (curr->next() != NULL) { 312 guarantee(curr->next()->prev() == curr, "Next or prev pointers messed up"); 313 } 314 guarantee(curr->hrm_index() == 0 || curr->hrm_index() > last_index, "List should be sorted"); 315 last_index = curr->hrm_index(); 316 317 capacity += curr->capacity(); 318 319 prev1 = prev0; 320 prev0 = curr; 321 curr = curr->next(); 322 } 323 324 guarantee(_tail == prev0, err_msg("Expected %s to end with %u but it ended with %u.", name(), _tail->hrm_index(), prev0->hrm_index())); 325 guarantee(_tail == NULL || _tail->next() == NULL, "_tail should not have a next"); 326 guarantee(length() == count, err_msg("%s count mismatch. Expected %u, actual %u.", name(), length(), count)); 327 guarantee(total_capacity_bytes() == capacity, err_msg("%s capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 328 name(), total_capacity_bytes(), capacity)); 329 } 330 331 // Note on the check_mt_safety() methods below: 332 // 333 // Verification of the "master" heap region sets / lists that are 334 // maintained by G1CollectedHeap is always done during a STW pause and 335 // by the VM thread at the start / end of the pause. The standard 336 // verification methods all assert check_mt_safety(). This is 337 // important as it ensures that verification is done without 338 // concurrent updates taking place at the same time. It follows, that, 339 // for the "master" heap region sets / lists, the check_mt_safety() 340 // method should include the VM thread / STW case. 341 342 void MasterFreeRegionListMtSafeChecker::check() { 343 // Master Free List MT safety protocol: 344 // (a) If we're at a safepoint, operations on the master free list 345 // should be invoked by either the VM thread (which will serialize 346 // them) or by the GC workers while holding the 347 // FreeList_lock. 348 // (b) If we're not at a safepoint, operations on the master free 349 // list should be invoked while holding the Heap_lock. 350 351 if (SafepointSynchronize::is_at_safepoint()) { 352 guarantee(Thread::current()->is_VM_thread() || 353 FreeList_lock->owned_by_self(), "master free list MT safety protocol at a safepoint"); 354 } else { 355 guarantee(Heap_lock->owned_by_self(), "master free list MT safety protocol outside a safepoint"); 356 } 357 } 358 359 void SecondaryFreeRegionListMtSafeChecker::check() { 360 // Secondary Free List MT safety protocol: 361 // Operations on the secondary free list should always be invoked 362 // while holding the SecondaryFreeList_lock. 363 364 guarantee(SecondaryFreeList_lock->owned_by_self(), "secondary free list MT safety protocol"); 365 } 366 367 void OldRegionSetMtSafeChecker::check() { 368 // Master Old Set MT safety protocol: 369 // (a) If we're at a safepoint, operations on the master old set 370 // should be invoked: 371 // - by the VM thread (which will serialize them), or 372 // - by the GC workers while holding the FreeList_lock, if we're 373 // at a safepoint for an evacuation pause (this lock is taken 374 // anyway when an GC alloc region is retired so that a new one 375 // is allocated from the free list), or 376 // - by the GC workers while holding the OldSets_lock, if we're at a 377 // safepoint for a cleanup pause. 378 // (b) If we're not at a safepoint, operations on the master old set 379 // should be invoked while holding the Heap_lock. 380 381 if (SafepointSynchronize::is_at_safepoint()) { 382 guarantee(Thread::current()->is_VM_thread() 383 || FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 384 "master old set MT safety protocol at a safepoint"); 385 } else { 386 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 387 } 388 } 389 390 void HumongousRegionSetMtSafeChecker::check() { 391 // Humongous Set MT safety protocol: 392 // (a) If we're at a safepoint, operations on the master humongous 393 // set should be invoked by either the VM thread (which will 394 // serialize them) or by the GC workers while holding the 395 // OldSets_lock. 396 // (b) If we're not at a safepoint, operations on the master 397 // humongous set should be invoked while holding the Heap_lock. 398 399 if (SafepointSynchronize::is_at_safepoint()) { 400 guarantee(Thread::current()->is_VM_thread() || 401 OldSets_lock->owned_by_self(), 402 "master humongous set MT safety protocol at a safepoint"); 403 } else { 404 guarantee(Heap_lock->owned_by_self(), 405 "master humongous set MT safety protocol outside a safepoint"); 406 } 407 } 408 409 void FreeRegionList_test() { 410 FreeRegionList l("test"); 411 412 const uint num_regions_in_test = 5; 413 // Create a fake heap. It does not need to be valid, as the HeapRegion constructor 414 // does not access it. 415 MemRegion heap(NULL, num_regions_in_test * HeapRegion::GrainWords); 416 // Allocate a fake BOT because the HeapRegion constructor initializes 417 // the BOT. 418 size_t bot_size = G1BlockOffsetSharedArray::compute_size(heap.word_size()); 419 HeapWord* bot_data = NEW_C_HEAP_ARRAY(HeapWord, bot_size, mtGC); 420 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(heap.word_size())); 421 G1RegionToSpaceMapper* bot_storage = 422 G1RegionToSpaceMapper::create_mapper(bot_rs, 423 os::vm_page_size(), 424 HeapRegion::GrainBytes, 425 G1BlockOffsetSharedArray::N_bytes, 426 mtGC); 427 G1BlockOffsetSharedArray oa(heap, bot_storage); 428 bot_storage->commit_regions(0, num_regions_in_test); 429 HeapRegion hr0(0, &oa, heap); 430 HeapRegion hr1(1, &oa, heap); 431 HeapRegion hr2(2, &oa, heap); 432 HeapRegion hr3(3, &oa, heap); 433 HeapRegion hr4(4, &oa, heap); 434 l.add_ordered(&hr1); 435 l.add_ordered(&hr0); 436 l.add_ordered(&hr3); 437 l.add_ordered(&hr4); 438 l.add_ordered(&hr2); 439 assert(l.length() == num_regions_in_test, "wrong length"); 440 l.verify_list(); 441 442 bot_storage->uncommit_regions(0, num_regions_in_test); 443 delete bot_storage; 444 FREE_C_HEAP_ARRAY(HeapWord, bot_data, mtGC); 445 }