1 /* 2 * Copyright (c) 1999, 2019, 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/shared/collectedHeap.hpp" 27 #include "gc/shared/threadLocalAllocBuffer.inline.hpp" 28 #include "logging/log.hpp" 29 #include "memory/resourceArea.hpp" 30 #include "memory/universe.hpp" 31 #include "oops/oop.inline.hpp" 32 #include "runtime/thread.inline.hpp" 33 #include "runtime/threadSMR.hpp" 34 #include "utilities/copy.hpp" 35 36 size_t ThreadLocalAllocBuffer::_max_size = 0; 37 int ThreadLocalAllocBuffer::_reserve_for_allocation_prefetch = 0; 38 unsigned int ThreadLocalAllocBuffer::_target_refills = 0; 39 40 size_t ThreadLocalAllocBuffer::remaining() { 41 if (end() == NULL) { 42 return 0; 43 } 44 45 return pointer_delta(hard_end(), top()); 46 } 47 48 void ThreadLocalAllocBuffer::accumulate_and_reset_statistics(ThreadLocalAllocStats* stats) { 49 Thread* thr = thread(); 50 size_t capacity = Universe::heap()->tlab_capacity(thr); 51 size_t used = Universe::heap()->tlab_used(thr); 52 53 _gc_waste += (unsigned)remaining(); 54 size_t total_allocated = thr->allocated_bytes(); 55 size_t allocated_since_last_gc = total_allocated - _allocated_before_last_gc; 56 _allocated_before_last_gc = total_allocated; 57 58 print_stats("gc"); 59 60 if (_number_of_refills > 0) { 61 // Update allocation history if a reasonable amount of eden was allocated. 62 bool update_allocation_history = used > 0.5 * capacity; 63 64 if (update_allocation_history) { 65 // Average the fraction of eden allocated in a tlab by this 66 // thread for use in the next resize operation. 67 // _gc_waste is not subtracted because it's included in 68 // "used". 69 // The result can be larger than 1.0 due to direct to old allocations. 70 // These allocations should ideally not be counted but since it is not possible 71 // to filter them out here we just cap the fraction to be at most 1.0. 72 double alloc_frac = MIN2(1.0, (double) allocated_since_last_gc / used); 73 _allocation_fraction.sample(alloc_frac); 74 } 75 76 stats->update_fast_allocations(_number_of_refills, 77 _allocated_size, 78 _gc_waste, 79 _fast_refill_waste, 80 _slow_refill_waste); 81 } else { 82 assert(_number_of_refills == 0 && _fast_refill_waste == 0 && 83 _slow_refill_waste == 0 && _gc_waste == 0, 84 "tlab stats == 0"); 85 } 86 87 stats->update_slow_allocations(_slow_allocations); 88 89 reset_statistics(); 90 } 91 92 void ThreadLocalAllocBuffer::insert_filler() { 93 assert(end() != NULL, "Must not be retired"); 94 if (top() < hard_end()) { 95 Universe::heap()->fill_with_dummy_object(top(), hard_end(), true); 96 } 97 } 98 99 void ThreadLocalAllocBuffer::make_parsable() { 100 if (end() != NULL) { 101 invariants(); 102 if (ZeroTLAB) { 103 retire(); 104 } else { 105 insert_filler(); 106 } 107 } 108 } 109 110 void ThreadLocalAllocBuffer::retire(ThreadLocalAllocStats* stats) { 111 if (stats != NULL) { 112 accumulate_and_reset_statistics(stats); 113 } 114 115 if (end() != NULL) { 116 invariants(); 117 thread()->incr_allocated_bytes(used_bytes()); 118 insert_filler(); 119 initialize(NULL, NULL, NULL); 120 } 121 } 122 123 void ThreadLocalAllocBuffer::retire_before_allocation() { 124 _slow_refill_waste += (unsigned int)remaining(); 125 retire(); 126 } 127 128 void ThreadLocalAllocBuffer::resize() { 129 // Compute the next tlab size using expected allocation amount 130 assert(ResizeTLAB, "Should not call this otherwise"); 131 size_t alloc = (size_t)(_allocation_fraction.average() * 132 (Universe::heap()->tlab_capacity(thread()) / HeapWordSize)); 133 size_t new_size = alloc / _target_refills; 134 135 new_size = clamp(new_size, min_size(), max_size()); 136 137 size_t aligned_new_size = align_object_size(new_size); 138 139 log_trace(gc, tlab)("TLAB new size: thread: " INTPTR_FORMAT " [id: %2d]" 140 " refills %d alloc: %8.6f desired_size: " SIZE_FORMAT " -> " SIZE_FORMAT, 141 p2i(thread()), thread()->osthread()->thread_id(), 142 _target_refills, _allocation_fraction.average(), desired_size(), aligned_new_size); 143 144 set_desired_size(aligned_new_size); 145 set_refill_waste_limit(initial_refill_waste_limit()); 146 } 147 148 void ThreadLocalAllocBuffer::reset_statistics() { 149 _number_of_refills = 0; 150 _fast_refill_waste = 0; 151 _slow_refill_waste = 0; 152 _gc_waste = 0; 153 _slow_allocations = 0; 154 _allocated_size = 0; 155 } 156 157 void ThreadLocalAllocBuffer::fill(HeapWord* start, 158 HeapWord* top, 159 size_t new_size) { 160 _number_of_refills++; 161 _allocated_size += new_size; 162 print_stats("fill"); 163 assert(top <= start + new_size - alignment_reserve(), "size too small"); 164 165 initialize(start, top, start + new_size - alignment_reserve()); 166 167 // Reset amount of internal fragmentation 168 set_refill_waste_limit(initial_refill_waste_limit()); 169 } 170 171 void ThreadLocalAllocBuffer::initialize(HeapWord* start, 172 HeapWord* top, 173 HeapWord* end) { 174 set_start(start); 175 set_top(top); 176 set_pf_top(top); 177 set_end(end); 178 set_allocation_end(end); 179 invariants(); 180 } 181 182 void ThreadLocalAllocBuffer::initialize() { 183 initialize(NULL, // start 184 NULL, // top 185 NULL); // end 186 187 set_desired_size(initial_desired_size()); 188 189 size_t capacity = Universe::heap()->tlab_capacity(thread()) / HeapWordSize; 190 double alloc_frac = desired_size() * target_refills() / (double) capacity; 191 _allocation_fraction.sample(alloc_frac); 192 193 set_refill_waste_limit(initial_refill_waste_limit()); 194 195 reset_statistics(); 196 } 197 198 void ThreadLocalAllocBuffer::startup_initialization() { 199 ThreadLocalAllocStats::initialize(); 200 201 // Assuming each thread's active tlab is, on average, 202 // 1/2 full at a GC 203 _target_refills = 100 / (2 * TLABWasteTargetPercent); 204 // We need to set initial target refills to 2 to avoid a GC which causes VM 205 // abort during VM initialization. 206 _target_refills = MAX2(_target_refills, 2U); 207 208 #ifdef COMPILER2 209 // If the C2 compiler is present, extra space is needed at the end of 210 // TLABs, otherwise prefetching instructions generated by the C2 211 // compiler will fault (due to accessing memory outside of heap). 212 // The amount of space is the max of the number of lines to 213 // prefetch for array and for instance allocations. (Extra space must be 214 // reserved to accommodate both types of allocations.) 215 // 216 // Only SPARC-specific BIS instructions are known to fault. (Those 217 // instructions are generated if AllocatePrefetchStyle==3 and 218 // AllocatePrefetchInstr==1). To be on the safe side, however, 219 // extra space is reserved for all combinations of 220 // AllocatePrefetchStyle and AllocatePrefetchInstr. 221 // 222 // If the C2 compiler is not present, no space is reserved. 223 224 // +1 for rounding up to next cache line, +1 to be safe 225 if (is_server_compilation_mode_vm()) { 226 int lines = MAX2(AllocatePrefetchLines, AllocateInstancePrefetchLines) + 2; 227 _reserve_for_allocation_prefetch = (AllocatePrefetchDistance + AllocatePrefetchStepSize * lines) / 228 (int)HeapWordSize; 229 } 230 #endif 231 232 // During jvm startup, the main thread is initialized 233 // before the heap is initialized. So reinitialize it now. 234 guarantee(Thread::current()->is_Java_thread(), "tlab initialization thread not Java thread"); 235 Thread::current()->tlab().initialize(); 236 237 log_develop_trace(gc, tlab)("TLAB min: " SIZE_FORMAT " initial: " SIZE_FORMAT " max: " SIZE_FORMAT, 238 min_size(), Thread::current()->tlab().initial_desired_size(), max_size()); 239 } 240 241 size_t ThreadLocalAllocBuffer::initial_desired_size() { 242 size_t init_sz = 0; 243 244 if (TLABSize > 0) { 245 init_sz = TLABSize / HeapWordSize; 246 } else { 247 // Initial size is a function of the average number of allocating threads. 248 unsigned int nof_threads = ThreadLocalAllocStats::allocating_threads_avg(); 249 250 init_sz = (Universe::heap()->tlab_capacity(thread()) / HeapWordSize) / 251 (nof_threads * target_refills()); 252 init_sz = align_object_size(init_sz); 253 } 254 // We can't use clamp() between min_size() and max_size() here because some 255 // options based on them may still be inconsistent; inconsistencies between 256 // those will be caught by following AfterMemoryInit constraint checking. 257 init_sz = MIN2(MAX2(init_sz, min_size()), max_size()); 258 return init_sz; 259 } 260 261 void ThreadLocalAllocBuffer::print_stats(const char* tag) { 262 Log(gc, tlab) log; 263 if (!log.is_trace()) { 264 return; 265 } 266 267 Thread* thrd = thread(); 268 size_t waste = _gc_waste + _slow_refill_waste + _fast_refill_waste; 269 double waste_percent = percent_of(waste, _allocated_size); 270 size_t tlab_used = Universe::heap()->tlab_used(thrd); 271 log.trace("TLAB: %s thread: " INTPTR_FORMAT " [id: %2d]" 272 " desired_size: " SIZE_FORMAT "KB" 273 " slow allocs: %d refill waste: " SIZE_FORMAT "B" 274 " alloc:%8.5f %8.0fKB refills: %d waste %4.1f%% gc: %dB" 275 " slow: %dB fast: %dB", 276 tag, p2i(thrd), thrd->osthread()->thread_id(), 277 _desired_size / (K / HeapWordSize), 278 _slow_allocations, _refill_waste_limit * HeapWordSize, 279 _allocation_fraction.average(), 280 _allocation_fraction.average() * tlab_used / K, 281 _number_of_refills, waste_percent, 282 _gc_waste * HeapWordSize, 283 _slow_refill_waste * HeapWordSize, 284 _fast_refill_waste * HeapWordSize); 285 } 286 287 void ThreadLocalAllocBuffer::set_sample_end(bool reset_byte_accumulation) { 288 size_t heap_words_remaining = pointer_delta(_end, _top); 289 size_t bytes_until_sample = thread()->heap_sampler().bytes_until_sample(); 290 size_t words_until_sample = bytes_until_sample / HeapWordSize; 291 292 if (reset_byte_accumulation) { 293 _bytes_since_last_sample_point = 0; 294 } 295 296 if (heap_words_remaining > words_until_sample) { 297 HeapWord* new_end = _top + words_until_sample; 298 set_end(new_end); 299 _bytes_since_last_sample_point += bytes_until_sample; 300 } else { 301 _bytes_since_last_sample_point += heap_words_remaining * HeapWordSize; 302 } 303 } 304 305 Thread* ThreadLocalAllocBuffer::thread() { 306 return (Thread*)(((char*)this) + in_bytes(start_offset()) - in_bytes(Thread::tlab_start_offset())); 307 } 308 309 void ThreadLocalAllocBuffer::set_back_allocation_end() { 310 _end = _allocation_end; 311 } 312 313 HeapWord* ThreadLocalAllocBuffer::hard_end() { 314 return _allocation_end + alignment_reserve(); 315 } 316 317 PerfVariable* ThreadLocalAllocStats::_perf_allocating_threads; 318 PerfVariable* ThreadLocalAllocStats::_perf_total_refills; 319 PerfVariable* ThreadLocalAllocStats::_perf_max_refills; 320 PerfVariable* ThreadLocalAllocStats::_perf_total_allocations; 321 PerfVariable* ThreadLocalAllocStats::_perf_total_gc_waste; 322 PerfVariable* ThreadLocalAllocStats::_perf_max_gc_waste; 323 PerfVariable* ThreadLocalAllocStats::_perf_total_slow_refill_waste; 324 PerfVariable* ThreadLocalAllocStats::_perf_max_slow_refill_waste; 325 PerfVariable* ThreadLocalAllocStats::_perf_total_fast_refill_waste; 326 PerfVariable* ThreadLocalAllocStats::_perf_max_fast_refill_waste; 327 PerfVariable* ThreadLocalAllocStats::_perf_total_slow_allocations; 328 PerfVariable* ThreadLocalAllocStats::_perf_max_slow_allocations; 329 AdaptiveWeightedAverage ThreadLocalAllocStats::_allocating_threads_avg(0); 330 331 static PerfVariable* create_perf_variable(const char* name, PerfData::Units unit, TRAPS) { 332 ResourceMark rm; 333 return PerfDataManager::create_variable(SUN_GC, PerfDataManager::counter_name("tlab", name), unit, THREAD); 334 } 335 336 void ThreadLocalAllocStats::initialize() { 337 _allocating_threads_avg = AdaptiveWeightedAverage(TLABAllocationWeight); 338 _allocating_threads_avg.sample(1); // One allocating thread at startup 339 340 if (UsePerfData) { 341 EXCEPTION_MARK; 342 _perf_allocating_threads = create_perf_variable("allocThreads", PerfData::U_None, CHECK); 343 _perf_total_refills = create_perf_variable("fills", PerfData::U_None, CHECK); 344 _perf_max_refills = create_perf_variable("maxFills", PerfData::U_None, CHECK); 345 _perf_total_allocations = create_perf_variable("alloc", PerfData::U_Bytes, CHECK); 346 _perf_total_gc_waste = create_perf_variable("gcWaste", PerfData::U_Bytes, CHECK); 347 _perf_max_gc_waste = create_perf_variable("maxGcWaste", PerfData::U_Bytes, CHECK); 348 _perf_total_slow_refill_waste = create_perf_variable("slowWaste", PerfData::U_Bytes, CHECK); 349 _perf_max_slow_refill_waste = create_perf_variable("maxSlowWaste", PerfData::U_Bytes, CHECK); 350 _perf_total_fast_refill_waste = create_perf_variable("fastWaste", PerfData::U_Bytes, CHECK); 351 _perf_max_fast_refill_waste = create_perf_variable("maxFastWaste", PerfData::U_Bytes, CHECK); 352 _perf_total_slow_allocations = create_perf_variable("slowAlloc", PerfData::U_None, CHECK); 353 _perf_max_slow_allocations = create_perf_variable("maxSlowAlloc", PerfData::U_None, CHECK); 354 } 355 } 356 357 ThreadLocalAllocStats::ThreadLocalAllocStats() : 358 _allocating_threads(0), 359 _total_refills(0), 360 _max_refills(0), 361 _total_allocations(0), 362 _total_gc_waste(0), 363 _max_gc_waste(0), 364 _total_fast_refill_waste(0), 365 _max_fast_refill_waste(0), 366 _total_slow_refill_waste(0), 367 _max_slow_refill_waste(0), 368 _total_slow_allocations(0), 369 _max_slow_allocations(0) {} 370 371 unsigned int ThreadLocalAllocStats::allocating_threads_avg() { 372 return MAX2((unsigned int)(_allocating_threads_avg.average() + 0.5), 1U); 373 } 374 375 void ThreadLocalAllocStats::update_fast_allocations(unsigned int refills, 376 size_t allocations, 377 size_t gc_waste, 378 size_t fast_refill_waste, 379 size_t slow_refill_waste) { 380 _allocating_threads += 1; 381 _total_refills += refills; 382 _max_refills = MAX2(_max_refills, refills); 383 _total_allocations += allocations; 384 _total_gc_waste += gc_waste; 385 _max_gc_waste = MAX2(_max_gc_waste, gc_waste); 386 _total_fast_refill_waste += fast_refill_waste; 387 _max_fast_refill_waste = MAX2(_max_fast_refill_waste, fast_refill_waste); 388 _total_slow_refill_waste += slow_refill_waste; 389 _max_slow_refill_waste = MAX2(_max_slow_refill_waste, slow_refill_waste); 390 } 391 392 void ThreadLocalAllocStats::update_slow_allocations(unsigned int allocations) { 393 _total_slow_allocations += allocations; 394 _max_slow_allocations = MAX2(_max_slow_allocations, allocations); 395 } 396 397 void ThreadLocalAllocStats::update(const ThreadLocalAllocStats& other) { 398 _allocating_threads += other._allocating_threads; 399 _total_refills += other._total_refills; 400 _max_refills = MAX2(_max_refills, other._max_refills); 401 _total_allocations += other._total_allocations; 402 _total_gc_waste += other._total_gc_waste; 403 _max_gc_waste = MAX2(_max_gc_waste, other._max_gc_waste); 404 _total_fast_refill_waste += other._total_fast_refill_waste; 405 _max_fast_refill_waste = MAX2(_max_fast_refill_waste, other._max_fast_refill_waste); 406 _total_slow_refill_waste += other._total_slow_refill_waste; 407 _max_slow_refill_waste = MAX2(_max_slow_refill_waste, other._max_slow_refill_waste); 408 _total_slow_allocations += other._total_slow_allocations; 409 _max_slow_allocations = MAX2(_max_slow_allocations, other._max_slow_allocations); 410 } 411 412 void ThreadLocalAllocStats::reset() { 413 _allocating_threads = 0; 414 _total_refills = 0; 415 _max_refills = 0; 416 _total_allocations = 0; 417 _total_gc_waste = 0; 418 _max_gc_waste = 0; 419 _total_fast_refill_waste = 0; 420 _max_fast_refill_waste = 0; 421 _total_slow_refill_waste = 0; 422 _max_slow_refill_waste = 0; 423 _total_slow_allocations = 0; 424 _max_slow_allocations = 0; 425 } 426 427 void ThreadLocalAllocStats::publish() { 428 if (_total_allocations == 0) { 429 return; 430 } 431 432 _allocating_threads_avg.sample(_allocating_threads); 433 434 const size_t waste = _total_gc_waste + _total_slow_refill_waste + _total_fast_refill_waste; 435 const double waste_percent = percent_of(waste, _total_allocations); 436 log_debug(gc, tlab)("TLAB totals: thrds: %d refills: %d max: %d" 437 " slow allocs: %d max %d waste: %4.1f%%" 438 " gc: " SIZE_FORMAT "B max: " SIZE_FORMAT "B" 439 " slow: " SIZE_FORMAT "B max: " SIZE_FORMAT "B" 440 " fast: " SIZE_FORMAT "B max: " SIZE_FORMAT "B", 441 _allocating_threads, _total_refills, _max_refills, 442 _total_slow_allocations, _max_slow_allocations, waste_percent, 443 _total_gc_waste * HeapWordSize, _max_gc_waste * HeapWordSize, 444 _total_slow_refill_waste * HeapWordSize, _max_slow_refill_waste * HeapWordSize, 445 _total_fast_refill_waste * HeapWordSize, _max_fast_refill_waste * HeapWordSize); 446 447 if (UsePerfData) { 448 _perf_allocating_threads ->set_value(_allocating_threads); 449 _perf_total_refills ->set_value(_total_refills); 450 _perf_max_refills ->set_value(_max_refills); 451 _perf_total_allocations ->set_value(_total_allocations); 452 _perf_total_gc_waste ->set_value(_total_gc_waste); 453 _perf_max_gc_waste ->set_value(_max_gc_waste); 454 _perf_total_slow_refill_waste ->set_value(_total_slow_refill_waste); 455 _perf_max_slow_refill_waste ->set_value(_max_slow_refill_waste); 456 _perf_total_fast_refill_waste ->set_value(_total_fast_refill_waste); 457 _perf_max_fast_refill_waste ->set_value(_max_fast_refill_waste); 458 _perf_total_slow_allocations ->set_value(_total_slow_allocations); 459 _perf_max_slow_allocations ->set_value(_max_slow_allocations); 460 } 461 } 462 463 size_t ThreadLocalAllocBuffer::end_reserve() { 464 size_t reserve_size = Universe::heap()->tlab_alloc_reserve(); 465 return MAX2(reserve_size, (size_t)_reserve_for_allocation_prefetch); 466 }