1 /* 2 * Copyright (c) 2001, 2023, 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/parallel/objectStartArray.inline.hpp" 27 #include "gc/parallel/parallelArguments.hpp" 28 #include "gc/parallel/parallelScavengeHeap.hpp" 29 #include "gc/parallel/psAdaptiveSizePolicy.hpp" 30 #include "gc/parallel/psCardTable.hpp" 31 #include "gc/parallel/psOldGen.hpp" 32 #include "gc/shared/cardTableBarrierSet.hpp" 33 #include "gc/shared/gcLocker.hpp" 34 #include "gc/shared/spaceDecorator.inline.hpp" 35 #include "logging/log.hpp" 36 #include "oops/oop.inline.hpp" 37 #include "runtime/java.hpp" 38 #include "utilities/align.hpp" 39 40 PSOldGen::PSOldGen(ReservedSpace rs, size_t initial_size, size_t min_size, 41 size_t max_size, const char* perf_data_name, int level): 42 _min_gen_size(min_size), 43 _max_gen_size(max_size) 44 { 45 initialize(rs, initial_size, GenAlignment, perf_data_name, level); 46 } 47 48 void PSOldGen::initialize(ReservedSpace rs, size_t initial_size, size_t alignment, 49 const char* perf_data_name, int level) { 50 initialize_virtual_space(rs, initial_size, alignment); 51 initialize_work(perf_data_name, level); 52 53 initialize_performance_counters(perf_data_name, level); 54 } 55 56 void PSOldGen::initialize_virtual_space(ReservedSpace rs, 57 size_t initial_size, 58 size_t alignment) { 59 60 _virtual_space = new PSVirtualSpace(rs, alignment); 61 if (!_virtual_space->expand_by(initial_size)) { 62 vm_exit_during_initialization("Could not reserve enough space for " 63 "object heap"); 64 } 65 } 66 67 void PSOldGen::initialize_work(const char* perf_data_name, int level) { 68 MemRegion const reserved_mr = reserved(); 69 assert(reserved_mr.byte_size() == max_gen_size(), "invariant"); 70 71 // Object start stuff: for all reserved memory 72 start_array()->initialize(reserved_mr); 73 74 // Card table stuff: for all committed memory 75 MemRegion committed_mr((HeapWord*)virtual_space()->low(), 76 (HeapWord*)virtual_space()->high()); 77 78 if (ZapUnusedHeapArea) { 79 // Mangle newly committed space immediately rather than 80 // waiting for the initialization of the space even though 81 // mangling is related to spaces. Doing it here eliminates 82 // the need to carry along information that a complete mangling 83 // (bottom to end) needs to be done. 84 SpaceMangler::mangle_region(committed_mr); 85 } 86 87 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 88 PSCardTable* ct = heap->card_table(); 89 ct->resize_covered_region(committed_mr); 90 91 // Verify that the start and end of this generation is the start of a card. 92 // If this wasn't true, a single card could span more than one generation, 93 // which would cause problems when we commit/uncommit memory, and when we 94 // clear and dirty cards. 95 guarantee(CardTable::is_card_aligned(reserved_mr.start()), "generation must be card aligned"); 96 // Check the heap layout documented at `class ParallelScavengeHeap`. 97 assert(reserved_mr.end() != heap->reserved_region().end(), "invariant"); 98 guarantee(CardTable::is_card_aligned(reserved_mr.end()), "generation must be card aligned"); 99 100 // 101 // ObjectSpace stuff 102 // 103 104 _object_space = new MutableSpace(virtual_space()->alignment()); 105 object_space()->initialize(committed_mr, 106 SpaceDecorator::Clear, 107 SpaceDecorator::Mangle, 108 MutableSpace::SetupPages, 109 &ParallelScavengeHeap::heap()->workers()); 110 111 // Update the start_array 112 start_array()->set_covered_region(committed_mr); 113 } 114 115 void PSOldGen::initialize_performance_counters(const char* perf_data_name, int level) { 116 // Generation Counters, generation 'level', 1 subspace 117 _gen_counters = new PSGenerationCounters(perf_data_name, level, 1, min_gen_size(), 118 max_gen_size(), virtual_space()); 119 _space_counters = new SpaceCounters(perf_data_name, 0, 120 virtual_space()->reserved_size(), 121 _object_space, _gen_counters); 122 } 123 124 // Assume that the generation has been allocated if its 125 // reserved size is not 0. 126 bool PSOldGen::is_allocated() { 127 return virtual_space()->reserved_size() != 0; 128 } 129 130 size_t PSOldGen::num_iterable_blocks() const { 131 return (object_space()->used_in_bytes() + IterateBlockSize - 1) / IterateBlockSize; 132 } 133 134 void PSOldGen::object_iterate_block(ObjectClosure* cl, size_t block_index) { 135 size_t block_word_size = IterateBlockSize / HeapWordSize; 136 assert((block_word_size % BOTConstants::card_size_in_words()) == 0, 137 "To ensure fast object_start calls"); 138 139 MutableSpace *space = object_space(); 140 141 HeapWord* begin = space->bottom() + block_index * block_word_size; 142 HeapWord* end = MIN2(space->top(), begin + block_word_size); 143 144 // Get object starting at or reaching into this block. 145 HeapWord* start = start_array()->object_start(begin); 146 if (start < begin) { 147 start += cast_to_oop(start)->size(); 148 } 149 assert(start >= begin, 150 "Object address" PTR_FORMAT " must be larger or equal to block address at " PTR_FORMAT, 151 p2i(start), p2i(begin)); 152 // Iterate all objects until the end. 153 for (HeapWord* p = start; p < end; p += cast_to_oop(p)->size()) { 154 cl->do_object(cast_to_oop(p)); 155 } 156 } 157 158 bool PSOldGen::expand_for_allocate(size_t word_size) { 159 assert(word_size > 0, "allocating zero words?"); 160 bool result = true; 161 { 162 MutexLocker x(PSOldGenExpand_lock); 163 // Avoid "expand storms" by rechecking available space after obtaining 164 // the lock, because another thread may have already made sufficient 165 // space available. If insufficient space available, that will remain 166 // true until we expand, since we have the lock. Other threads may take 167 // the space we need before we can allocate it, regardless of whether we 168 // expand. That's okay, we'll just try expanding again. 169 if (object_space()->needs_expand(word_size)) { 170 result = expand(word_size*HeapWordSize); 171 } 172 } 173 if (GCExpandToAllocateDelayMillis > 0) { 174 os::naked_sleep(GCExpandToAllocateDelayMillis); 175 } 176 return result; 177 } 178 179 bool PSOldGen::expand(size_t bytes) { 180 assert_lock_strong(PSOldGenExpand_lock); 181 assert_locked_or_safepoint(Heap_lock); 182 assert(bytes > 0, "precondition"); 183 const size_t alignment = virtual_space()->alignment(); 184 size_t aligned_bytes = align_up(bytes, alignment); 185 size_t aligned_expand_bytes = align_up(MinHeapDeltaBytes, alignment); 186 187 if (UseNUMA) { 188 // With NUMA we use round-robin page allocation for the old gen. Expand by at least 189 // providing a page per lgroup. Alignment is larger or equal to the page size. 190 aligned_expand_bytes = MAX2(aligned_expand_bytes, alignment * os::numa_get_groups_num()); 191 } 192 if (aligned_bytes == 0) { 193 // The alignment caused the number of bytes to wrap. A call to expand 194 // implies a best effort to expand by "bytes" but not a guarantee. Align 195 // down to give a best effort. This is likely the most that the generation 196 // can expand since it has some capacity to start with. 197 aligned_bytes = align_down(bytes, alignment); 198 } 199 200 bool success = false; 201 if (aligned_expand_bytes > aligned_bytes) { 202 success = expand_by(aligned_expand_bytes); 203 } 204 if (!success) { 205 success = expand_by(aligned_bytes); 206 } 207 if (!success) { 208 success = expand_to_reserved(); 209 } 210 211 if (success && GCLocker::is_active_and_needs_gc()) { 212 log_debug(gc)("Garbage collection disabled, expanded heap instead"); 213 } 214 return success; 215 } 216 217 bool PSOldGen::expand_by(size_t bytes) { 218 assert_lock_strong(PSOldGenExpand_lock); 219 assert_locked_or_safepoint(Heap_lock); 220 assert(bytes > 0, "precondition"); 221 bool result = virtual_space()->expand_by(bytes); 222 if (result) { 223 if (ZapUnusedHeapArea) { 224 // We need to mangle the newly expanded area. The memregion spans 225 // end -> new_end, we assume that top -> end is already mangled. 226 // Do the mangling before post_resize() is called because 227 // the space is available for allocation after post_resize(); 228 HeapWord* const virtual_space_high = (HeapWord*) virtual_space()->high(); 229 assert(object_space()->end() < virtual_space_high, 230 "Should be true before post_resize()"); 231 MemRegion mangle_region(object_space()->end(), virtual_space_high); 232 // Note that the object space has not yet been updated to 233 // coincide with the new underlying virtual space. 234 SpaceMangler::mangle_region(mangle_region); 235 } 236 post_resize(); 237 if (UsePerfData) { 238 _space_counters->update_capacity(); 239 _gen_counters->update_all(); 240 } 241 } 242 243 if (result) { 244 size_t new_mem_size = virtual_space()->committed_size(); 245 size_t old_mem_size = new_mem_size - bytes; 246 log_debug(gc)("Expanding %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K", 247 name(), old_mem_size/K, bytes/K, new_mem_size/K); 248 } 249 250 return result; 251 } 252 253 bool PSOldGen::expand_to_reserved() { 254 assert_lock_strong(PSOldGenExpand_lock); 255 assert_locked_or_safepoint(Heap_lock); 256 257 bool result = false; 258 const size_t remaining_bytes = virtual_space()->uncommitted_size(); 259 if (remaining_bytes > 0) { 260 result = expand_by(remaining_bytes); 261 DEBUG_ONLY(if (!result) log_warning(gc)("grow to reserve failed")); 262 } 263 return result; 264 } 265 266 void PSOldGen::shrink(size_t bytes) { 267 assert_lock_strong(PSOldGenExpand_lock); 268 assert_locked_or_safepoint(Heap_lock); 269 270 size_t size = align_down(bytes, virtual_space()->alignment()); 271 if (size > 0) { 272 virtual_space()->shrink_by(bytes); 273 post_resize(); 274 275 size_t new_mem_size = virtual_space()->committed_size(); 276 size_t old_mem_size = new_mem_size + bytes; 277 log_debug(gc)("Shrinking %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K", 278 name(), old_mem_size/K, bytes/K, new_mem_size/K); 279 } 280 } 281 282 void PSOldGen::complete_loaded_archive_space(MemRegion archive_space) { 283 HeapWord* cur = archive_space.start(); 284 while (cur < archive_space.end()) { 285 size_t word_size = cast_to_oop(cur)->size(); 286 _start_array.update_for_block(cur, cur + word_size); 287 cur += word_size; 288 } 289 } 290 291 void PSOldGen::resize(size_t desired_free_space) { 292 const size_t alignment = virtual_space()->alignment(); 293 const size_t size_before = virtual_space()->committed_size(); 294 size_t new_size = used_in_bytes() + desired_free_space; 295 if (new_size < used_in_bytes()) { 296 // Overflowed the addition. 297 new_size = max_gen_size(); 298 } 299 // Adjust according to our min and max 300 new_size = clamp(new_size, min_gen_size(), max_gen_size()); 301 302 new_size = align_up(new_size, alignment); 303 304 const size_t current_size = capacity_in_bytes(); 305 306 log_trace(gc, ergo)("AdaptiveSizePolicy::old generation size: " 307 "desired free: " SIZE_FORMAT " used: " SIZE_FORMAT 308 " new size: " SIZE_FORMAT " current size " SIZE_FORMAT 309 " gen limits: " SIZE_FORMAT " / " SIZE_FORMAT, 310 desired_free_space, used_in_bytes(), new_size, current_size, 311 max_gen_size(), min_gen_size()); 312 313 if (new_size == current_size) { 314 // No change requested 315 return; 316 } 317 if (new_size > current_size) { 318 size_t change_bytes = new_size - current_size; 319 MutexLocker x(PSOldGenExpand_lock); 320 expand(change_bytes); 321 } else { 322 size_t change_bytes = current_size - new_size; 323 MutexLocker x(PSOldGenExpand_lock); 324 shrink(change_bytes); 325 } 326 327 log_trace(gc, ergo)("AdaptiveSizePolicy::old generation size: collection: %d (" SIZE_FORMAT ") -> (" SIZE_FORMAT ") ", 328 ParallelScavengeHeap::heap()->total_collections(), 329 size_before, 330 virtual_space()->committed_size()); 331 } 332 333 // NOTE! We need to be careful about resizing. During a GC, multiple 334 // allocators may be active during heap expansion. If we allow the 335 // heap resizing to become visible before we have correctly resized 336 // all heap related data structures, we may cause program failures. 337 void PSOldGen::post_resize() { 338 // First construct a memregion representing the new size 339 MemRegion new_memregion((HeapWord*)virtual_space()->low(), 340 (HeapWord*)virtual_space()->high()); 341 size_t new_word_size = new_memregion.word_size(); 342 343 start_array()->set_covered_region(new_memregion); 344 ParallelScavengeHeap::heap()->card_table()->resize_covered_region(new_memregion); 345 346 WorkerThreads* workers = Thread::current()->is_VM_thread() ? 347 &ParallelScavengeHeap::heap()->workers() : nullptr; 348 349 // The update of the space's end is done by this call. As that 350 // makes the new space available for concurrent allocation, this 351 // must be the last step when expanding. 352 object_space()->initialize(new_memregion, 353 SpaceDecorator::DontClear, 354 SpaceDecorator::DontMangle, 355 MutableSpace::SetupPages, 356 workers); 357 358 assert(new_word_size == heap_word_size(object_space()->capacity_in_bytes()), 359 "Sanity"); 360 } 361 362 void PSOldGen::print() const { print_on(tty);} 363 void PSOldGen::print_on(outputStream* st) const { 364 st->print(" %-15s", name()); 365 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K", 366 capacity_in_bytes()/K, used_in_bytes()/K); 367 st->print_cr(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")", 368 p2i(virtual_space()->low_boundary()), 369 p2i(virtual_space()->high()), 370 p2i(virtual_space()->high_boundary())); 371 372 st->print(" object"); object_space()->print_on(st); 373 } 374 375 void PSOldGen::update_counters() { 376 if (UsePerfData) { 377 _space_counters->update_all(); 378 _gen_counters->update_all(); 379 } 380 } 381 382 void PSOldGen::verify() { 383 object_space()->verify(); 384 } 385 386 class VerifyObjectStartArrayClosure : public ObjectClosure { 387 ObjectStartArray* _start_array; 388 389 public: 390 VerifyObjectStartArrayClosure(ObjectStartArray* start_array) : 391 _start_array(start_array) { } 392 393 virtual void do_object(oop obj) { 394 // With compact headers, the objects can be one-word sized. 395 size_t int_off = UseCompactObjectHeaders ? MIN2((size_t)1, obj->size() - 1) : 1; 396 HeapWord* test_addr = cast_from_oop<HeapWord*>(obj) + int_off; 397 guarantee(_start_array->object_start(test_addr) == cast_from_oop<HeapWord*>(obj), "ObjectStartArray cannot find start of object"); 398 } 399 }; 400 401 void PSOldGen::verify_object_start_array() { 402 VerifyObjectStartArrayClosure check(&_start_array); 403 object_iterate(&check); 404 } 405 406 #ifndef PRODUCT 407 void PSOldGen::record_spaces_top() { 408 assert(ZapUnusedHeapArea, "Not mangling unused space"); 409 object_space()->set_top_for_allocations(); 410 } 411 #endif