1 /* 2 * Copyright (c) 2011, 2015, 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/g1/g1CollectedHeap.inline.hpp" 27 #include "gc/g1/heapRegionRemSet.hpp" 28 #include "gc/g1/heapRegionSet.inline.hpp" 29 30 uint FreeRegionList::_unrealistically_long_length = 0; 31 32 void HeapRegionSetBase::fill_in_ext_msg(hrs_ext_msg* msg, const char* message) { 33 msg->append("[%s] %s ln: %u cy: "SIZE_FORMAT, 34 name(), message, length(), total_capacity_bytes()); 35 fill_in_ext_msg_extra(msg); 36 } 37 38 #ifndef PRODUCT 39 void HeapRegionSetBase::verify_region(HeapRegion* hr) { 40 assert(hr->containing_set() == this, err_msg("Inconsistent containing set for %u", hr->hrm_index())); 41 assert(!hr->is_young(), err_msg("Adding young region %u", hr->hrm_index())); // currently we don't use these sets for young regions 42 assert(hr->is_humongous() == regions_humongous(), err_msg("Wrong humongous state for region %u and set %s", hr->hrm_index(), name())); 43 assert(hr->is_free() == regions_free(), err_msg("Wrong free state for region %u and set %s", hr->hrm_index(), name())); 44 assert(!hr->is_free() || hr->is_empty(), err_msg("Free region %u is not empty for set %s", hr->hrm_index(), name())); 45 assert(!hr->is_empty() || hr->is_free(), err_msg("Empty region %u is not free for set %s", hr->hrm_index(), name())); 46 assert(hr->rem_set()->verify_ready_for_par_iteration(), err_msg("Wrong iteration state %u", hr->hrm_index())); 47 } 48 #endif 49 50 void HeapRegionSetBase::verify() { 51 // It's important that we also observe the MT safety protocol even 52 // for the verification calls. If we do verification without the 53 // appropriate locks and the set changes underneath our feet 54 // verification might fail and send us on a wild goose chase. 55 check_mt_safety(); 56 57 guarantee(( is_empty() && length() == 0 && total_capacity_bytes() == 0) || 58 (!is_empty() && length() > 0 && total_capacity_bytes() > 0) , 59 hrs_ext_msg(this, "invariant")); 60 } 61 62 void HeapRegionSetBase::verify_start() { 63 // See comment in verify() about MT safety and verification. 64 check_mt_safety(); 65 assert(!_verify_in_progress, 66 hrs_ext_msg(this, "verification should not be in progress")); 67 68 // Do the basic verification first before we do the checks over the regions. 69 HeapRegionSetBase::verify(); 70 71 _verify_in_progress = true; 72 } 73 74 void HeapRegionSetBase::verify_end() { 75 // See comment in verify() about MT safety and verification. 76 check_mt_safety(); 77 assert(_verify_in_progress, 78 hrs_ext_msg(this, "verification should be in progress")); 79 80 _verify_in_progress = false; 81 } 82 83 void HeapRegionSetBase::print_on(outputStream* out, bool print_contents) { 84 out->cr(); 85 out->print_cr("Set: %s ("PTR_FORMAT")", name(), p2i(this)); 86 out->print_cr(" Region Assumptions"); 87 out->print_cr(" humongous : %s", BOOL_TO_STR(regions_humongous())); 88 out->print_cr(" free : %s", BOOL_TO_STR(regions_free())); 89 out->print_cr(" Attributes"); 90 out->print_cr(" length : %14u", length()); 91 out->print_cr(" total capacity : "SIZE_FORMAT_W(14)" bytes", 92 total_capacity_bytes()); 93 } 94 95 HeapRegionSetBase::HeapRegionSetBase(const char* name, bool humongous, bool free, HRSMtSafeChecker* mt_safety_checker) 96 : _name(name), _verify_in_progress(false), 97 _is_humongous(humongous), _is_free(free), _mt_safety_checker(mt_safety_checker), 98 _count() 99 { } 100 101 void FreeRegionList::set_unrealistically_long_length(uint len) { 102 guarantee(_unrealistically_long_length == 0, "should only be set once"); 103 _unrealistically_long_length = len; 104 } 105 106 void FreeRegionList::fill_in_ext_msg_extra(hrs_ext_msg* msg) { 107 msg->append(" hd: "PTR_FORMAT" tl: "PTR_FORMAT, p2i(_head), p2i(_tail)); 108 } 109 110 void FreeRegionList::remove_all() { 111 check_mt_safety(); 112 verify_optional(); 113 114 HeapRegion* curr = _head; 115 while (curr != NULL) { 116 verify_region(curr); 117 118 HeapRegion* next = curr->next(); 119 curr->set_next(NULL); 120 curr->set_prev(NULL); 121 curr->set_containing_set(NULL); 122 curr = next; 123 } 124 clear(); 125 126 verify_optional(); 127 } 128 129 void FreeRegionList::add_ordered(FreeRegionList* from_list) { 130 check_mt_safety(); 131 from_list->check_mt_safety(); 132 133 verify_optional(); 134 from_list->verify_optional(); 135 136 if (from_list->is_empty()) { 137 return; 138 } 139 140 #ifdef ASSERT 141 FreeRegionListIterator iter(from_list); 142 while (iter.more_available()) { 143 HeapRegion* hr = iter.get_next(); 144 // In set_containing_set() we check that we either set the value 145 // from NULL to non-NULL or vice versa to catch bugs. So, we have 146 // to NULL it first before setting it to the value. 147 hr->set_containing_set(NULL); 148 hr->set_containing_set(this); 149 } 150 #endif // ASSERT 151 152 if (is_empty()) { 153 assert(length() == 0 && _tail == NULL, hrs_ext_msg(this, "invariant")); 154 _head = from_list->_head; 155 _tail = from_list->_tail; 156 } else { 157 HeapRegion* curr_to = _head; 158 HeapRegion* curr_from = from_list->_head; 159 160 while (curr_from != NULL) { 161 while (curr_to != NULL && curr_to->hrm_index() < curr_from->hrm_index()) { 162 curr_to = curr_to->next(); 163 } 164 165 if (curr_to == NULL) { 166 // The rest of the from list should be added as tail 167 _tail->set_next(curr_from); 168 curr_from->set_prev(_tail); 169 curr_from = NULL; 170 } else { 171 HeapRegion* next_from = curr_from->next(); 172 173 curr_from->set_next(curr_to); 174 curr_from->set_prev(curr_to->prev()); 175 if (curr_to->prev() == NULL) { 176 _head = curr_from; 177 } else { 178 curr_to->prev()->set_next(curr_from); 179 } 180 curr_to->set_prev(curr_from); 181 182 curr_from = next_from; 183 } 184 } 185 186 if (_tail->hrm_index() < from_list->_tail->hrm_index()) { 187 _tail = from_list->_tail; 188 } 189 } 190 191 _count.increment(from_list->length(), from_list->total_capacity_bytes()); 192 from_list->clear(); 193 194 verify_optional(); 195 from_list->verify_optional(); 196 } 197 198 void FreeRegionList::remove_starting_at(HeapRegion* first, uint num_regions) { 199 check_mt_safety(); 200 assert(num_regions >= 1, hrs_ext_msg(this, "pre-condition")); 201 assert(!is_empty(), hrs_ext_msg(this, "pre-condition")); 202 203 verify_optional(); 204 DEBUG_ONLY(uint old_length = length();) 205 206 HeapRegion* curr = first; 207 uint count = 0; 208 while (count < num_regions) { 209 verify_region(curr); 210 HeapRegion* next = curr->next(); 211 HeapRegion* prev = curr->prev(); 212 213 assert(count < num_regions, 214 hrs_err_msg("[%s] should not come across more regions " 215 "pending for removal than num_regions: %u", 216 name(), num_regions)); 217 218 if (prev == NULL) { 219 assert(_head == curr, hrs_ext_msg(this, "invariant")); 220 _head = next; 221 } else { 222 assert(_head != curr, hrs_ext_msg(this, "invariant")); 223 prev->set_next(next); 224 } 225 if (next == NULL) { 226 assert(_tail == curr, hrs_ext_msg(this, "invariant")); 227 _tail = prev; 228 } else { 229 assert(_tail != curr, hrs_ext_msg(this, "invariant")); 230 next->set_prev(prev); 231 } 232 if (_last = curr) { 233 _last = NULL; 234 } 235 236 curr->set_next(NULL); 237 curr->set_prev(NULL); 238 remove(curr); 239 240 count++; 241 curr = next; 242 } 243 244 assert(count == num_regions, 245 hrs_err_msg("[%s] count: %u should be == num_regions: %u", 246 name(), count, num_regions)); 247 assert(length() + num_regions == old_length, 248 hrs_err_msg("[%s] new length should be consistent " 249 "new length: %u old length: %u num_regions: %u", 250 name(), length(), old_length, num_regions)); 251 252 verify_optional(); 253 } 254 255 void FreeRegionList::verify() { 256 // See comment in HeapRegionSetBase::verify() about MT safety and 257 // verification. 258 check_mt_safety(); 259 260 // This will also do the basic verification too. 261 verify_start(); 262 263 verify_list(); 264 265 verify_end(); 266 } 267 268 void FreeRegionList::clear() { 269 _count = HeapRegionSetCount(); 270 _head = NULL; 271 _tail = NULL; 272 _last = NULL; 273 } 274 275 void FreeRegionList::print_on(outputStream* out, bool print_contents) { 276 HeapRegionSetBase::print_on(out, print_contents); 277 out->print_cr(" Linking"); 278 out->print_cr(" head : "PTR_FORMAT, p2i(_head)); 279 out->print_cr(" tail : "PTR_FORMAT, p2i(_tail)); 280 281 if (print_contents) { 282 out->print_cr(" Contents"); 283 FreeRegionListIterator iter(this); 284 while (iter.more_available()) { 285 HeapRegion* hr = iter.get_next(); 286 hr->print_on(out); 287 } 288 } 289 290 out->cr(); 291 } 292 293 void FreeRegionList::verify_list() { 294 HeapRegion* curr = _head; 295 HeapRegion* prev1 = NULL; 296 HeapRegion* prev0 = NULL; 297 uint count = 0; 298 size_t capacity = 0; 299 uint last_index = 0; 300 301 guarantee(_head == NULL || _head->prev() == NULL, "_head should not have a prev"); 302 while (curr != NULL) { 303 verify_region(curr); 304 305 count++; 306 guarantee(count < _unrealistically_long_length, 307 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", 308 name(), count, p2i(curr), p2i(prev0), p2i(prev1), length())); 309 310 if (curr->next() != NULL) { 311 guarantee(curr->next()->prev() == curr, "Next or prev pointers messed up"); 312 } 313 guarantee(curr->hrm_index() == 0 || curr->hrm_index() > last_index, "List should be sorted"); 314 last_index = curr->hrm_index(); 315 316 capacity += curr->capacity(); 317 318 prev1 = prev0; 319 prev0 = curr; 320 curr = curr->next(); 321 } 322 323 guarantee(_tail == prev0, err_msg("Expected %s to end with %u but it ended with %u.", name(), _tail->hrm_index(), prev0->hrm_index())); 324 guarantee(_tail == NULL || _tail->next() == NULL, "_tail should not have a next"); 325 guarantee(length() == count, err_msg("%s count mismatch. Expected %u, actual %u.", name(), length(), count)); 326 guarantee(total_capacity_bytes() == capacity, err_msg("%s capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT, 327 name(), total_capacity_bytes(), capacity)); 328 } 329 330 // Note on the check_mt_safety() methods below: 331 // 332 // Verification of the "master" heap region sets / lists that are 333 // maintained by G1CollectedHeap is always done during a STW pause and 334 // by the VM thread at the start / end of the pause. The standard 335 // verification methods all assert check_mt_safety(). This is 336 // important as it ensures that verification is done without 337 // concurrent updates taking place at the same time. It follows, that, 338 // for the "master" heap region sets / lists, the check_mt_safety() 339 // method should include the VM thread / STW case. 340 341 void MasterFreeRegionListMtSafeChecker::check() { 342 // Master Free List MT safety protocol: 343 // (a) If we're at a safepoint, operations on the master free list 344 // should be invoked by either the VM thread (which will serialize 345 // them) or by the GC workers while holding the 346 // FreeList_lock. 347 // (b) If we're not at a safepoint, operations on the master free 348 // list should be invoked while holding the Heap_lock. 349 350 if (SafepointSynchronize::is_at_safepoint()) { 351 guarantee(Thread::current()->is_VM_thread() || 352 FreeList_lock->owned_by_self(), "master free list MT safety protocol at a safepoint"); 353 } else { 354 guarantee(Heap_lock->owned_by_self(), "master free list MT safety protocol outside a safepoint"); 355 } 356 } 357 358 void SecondaryFreeRegionListMtSafeChecker::check() { 359 // Secondary Free List MT safety protocol: 360 // Operations on the secondary free list should always be invoked 361 // while holding the SecondaryFreeList_lock. 362 363 guarantee(SecondaryFreeList_lock->owned_by_self(), "secondary free list MT safety protocol"); 364 } 365 366 void OldRegionSetMtSafeChecker::check() { 367 // Master Old Set MT safety protocol: 368 // (a) If we're at a safepoint, operations on the master old set 369 // should be invoked: 370 // - by the VM thread (which will serialize them), or 371 // - by the GC workers while holding the FreeList_lock, if we're 372 // at a safepoint for an evacuation pause (this lock is taken 373 // anyway when an GC alloc region is retired so that a new one 374 // is allocated from the free list), or 375 // - by the GC workers while holding the OldSets_lock, if we're at a 376 // safepoint for a cleanup pause. 377 // (b) If we're not at a safepoint, operations on the master old set 378 // should be invoked while holding the Heap_lock. 379 380 if (SafepointSynchronize::is_at_safepoint()) { 381 guarantee(Thread::current()->is_VM_thread() 382 || FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(), 383 "master old set MT safety protocol at a safepoint"); 384 } else { 385 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint"); 386 } 387 } 388 389 void HumongousRegionSetMtSafeChecker::check() { 390 // Humongous Set MT safety protocol: 391 // (a) If we're at a safepoint, operations on the master humongous 392 // set should be invoked by either the VM thread (which will 393 // serialize them) or by the GC workers while holding the 394 // OldSets_lock. 395 // (b) If we're not at a safepoint, operations on the master 396 // humongous set should be invoked while holding the Heap_lock. 397 398 if (SafepointSynchronize::is_at_safepoint()) { 399 guarantee(Thread::current()->is_VM_thread() || 400 OldSets_lock->owned_by_self(), 401 "master humongous set MT safety protocol at a safepoint"); 402 } else { 403 guarantee(Heap_lock->owned_by_self(), 404 "master humongous set MT safety protocol outside a safepoint"); 405 } 406 } 407 408 void FreeRegionList_test() { 409 FreeRegionList l("test"); 410 411 const uint num_regions_in_test = 5; 412 // Create a fake heap. It does not need to be valid, as the HeapRegion constructor 413 // does not access it. 414 MemRegion heap(NULL, num_regions_in_test * HeapRegion::GrainWords); 415 // Allocate a fake BOT because the HeapRegion constructor initializes 416 // the BOT. 417 size_t bot_size = G1BlockOffsetSharedArray::compute_size(heap.word_size()); 418 HeapWord* bot_data = NEW_C_HEAP_ARRAY(HeapWord, bot_size, mtGC); 419 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(heap.word_size())); 420 G1RegionToSpaceMapper* bot_storage = 421 G1RegionToSpaceMapper::create_mapper(bot_rs, 422 bot_rs.size(), 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); 429 430 // Set up memory regions for the heap regions. 431 MemRegion mr0(heap.start(), HeapRegion::GrainWords); 432 MemRegion mr1(mr0.end(), HeapRegion::GrainWords); 433 MemRegion mr2(mr1.end(), HeapRegion::GrainWords); 434 MemRegion mr3(mr2.end(), HeapRegion::GrainWords); 435 MemRegion mr4(mr3.end(), HeapRegion::GrainWords); 436 437 HeapRegion hr0(0, &oa, mr0); 438 HeapRegion hr1(1, &oa, mr1); 439 HeapRegion hr2(2, &oa, mr2); 440 HeapRegion hr3(3, &oa, mr3); 441 HeapRegion hr4(4, &oa, mr4); 442 l.add_ordered(&hr1); 443 l.add_ordered(&hr0); 444 l.add_ordered(&hr3); 445 l.add_ordered(&hr4); 446 l.add_ordered(&hr2); 447 assert(l.length() == num_regions_in_test, "wrong length"); 448 l.verify_list(); 449 450 bot_storage->uncommit_regions(0, num_regions_in_test); 451 delete bot_storage; 452 FREE_C_HEAP_ARRAY(HeapWord, bot_data); 453 }