1 /* 2 * Copyright (c) 1999, 2017, 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/genCollectedHeap.hpp" 27 #include "gc/shared/threadLocalAllocBuffer.inline.hpp" 28 #include "logging/log.hpp" 29 #include "memory/resourceArea.hpp" 30 #include "memory/universe.inline.hpp" 31 #include "oops/oop.inline.hpp" 32 #include "runtime/heapMonitoring.hpp" 33 #include "runtime/thread.inline.hpp" 34 #include "runtime/threadSMR.hpp" 35 #include "utilities/copy.hpp" 36 37 // Thread-Local Edens support 38 39 // static member initialization 40 size_t ThreadLocalAllocBuffer::_max_size = 0; 41 int ThreadLocalAllocBuffer::_reserve_for_allocation_prefetch = 0; 42 unsigned ThreadLocalAllocBuffer::_target_refills = 0; 43 GlobalTLABStats* ThreadLocalAllocBuffer::_global_stats = NULL; 44 45 void ThreadLocalAllocBuffer::clear_before_allocation() { 46 _slow_refill_waste += (unsigned)remaining(); 47 make_parsable(true); // also retire the TLAB 48 } 49 50 void ThreadLocalAllocBuffer::accumulate_statistics_before_gc() { 51 global_stats()->initialize(); 52 53 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) { 54 thread->tlab().accumulate_statistics(); 55 thread->tlab().initialize_statistics(); 56 } 57 58 // Publish new stats if some allocation occurred. 59 if (global_stats()->allocation() != 0) { 60 global_stats()->publish(); 61 global_stats()->print(); 62 } 63 } 64 65 void ThreadLocalAllocBuffer::accumulate_statistics() { 66 Thread* thread = myThread(); 67 size_t capacity = Universe::heap()->tlab_capacity(thread); 68 size_t used = Universe::heap()->tlab_used(thread); 69 70 _gc_waste += (unsigned)remaining(); 71 size_t total_allocated = thread->allocated_bytes(); 72 size_t allocated_since_last_gc = total_allocated - _allocated_before_last_gc; 73 _allocated_before_last_gc = total_allocated; 74 75 print_stats("gc"); 76 77 if (_number_of_refills > 0) { 78 // Update allocation history if a reasonable amount of eden was allocated. 79 bool update_allocation_history = used > 0.5 * capacity; 80 81 if (update_allocation_history) { 82 // Average the fraction of eden allocated in a tlab by this 83 // thread for use in the next resize operation. 84 // _gc_waste is not subtracted because it's included in 85 // "used". 86 // The result can be larger than 1.0 due to direct to old allocations. 87 // These allocations should ideally not be counted but since it is not possible 88 // to filter them out here we just cap the fraction to be at most 1.0. 89 double alloc_frac = MIN2(1.0, (double) allocated_since_last_gc / used); 90 _allocation_fraction.sample(alloc_frac); 91 } 92 global_stats()->update_allocating_threads(); 93 global_stats()->update_number_of_refills(_number_of_refills); 94 global_stats()->update_allocation(_number_of_refills * desired_size()); 95 global_stats()->update_gc_waste(_gc_waste); 96 global_stats()->update_slow_refill_waste(_slow_refill_waste); 97 global_stats()->update_fast_refill_waste(_fast_refill_waste); 98 99 } else { 100 assert(_number_of_refills == 0 && _fast_refill_waste == 0 && 101 _slow_refill_waste == 0 && _gc_waste == 0, 102 "tlab stats == 0"); 103 } 104 global_stats()->update_slow_allocations(_slow_allocations); 105 } 106 107 // Fills the current tlab with a dummy filler array to create 108 // an illusion of a contiguous Eden and optionally retires the tlab. 109 // Waste accounting should be done in caller as appropriate; see, 110 // for example, clear_before_allocation(). 111 void ThreadLocalAllocBuffer::make_parsable(bool retire, bool zap) { 112 if (end() != NULL) { 113 invariants(); 114 115 if (retire) { 116 myThread()->incr_allocated_bytes(used_bytes()); 117 } 118 119 CollectedHeap::fill_with_object(top(), hard_end(), retire && zap); 120 121 if (retire || ZeroTLAB) { // "Reset" the TLAB 122 set_start(NULL); 123 set_top(NULL); 124 set_pf_top(NULL); 125 set_end(NULL); 126 set_actual_end(NULL); 127 set_slow_path_end(NULL); 128 } 129 } 130 assert(!(retire || ZeroTLAB) || 131 (start() == NULL && end() == NULL && top() == NULL && 132 _actual_end == NULL && _slow_path_end == NULL), 133 "TLAB must be reset"); 134 } 135 136 void ThreadLocalAllocBuffer::resize_all_tlabs() { 137 if (ResizeTLAB) { 138 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) { 139 thread->tlab().resize(); 140 } 141 } 142 } 143 144 void ThreadLocalAllocBuffer::resize() { 145 // Compute the next tlab size using expected allocation amount 146 assert(ResizeTLAB, "Should not call this otherwise"); 147 size_t alloc = (size_t)(_allocation_fraction.average() * 148 (Universe::heap()->tlab_capacity(myThread()) / HeapWordSize)); 149 size_t new_size = alloc / _target_refills; 150 151 new_size = MIN2(MAX2(new_size, min_size()), max_size()); 152 153 size_t aligned_new_size = align_object_size(new_size); 154 155 log_trace(gc, tlab)("TLAB new size: thread: " INTPTR_FORMAT " [id: %2d]" 156 " refills %d alloc: %8.6f desired_size: " SIZE_FORMAT " -> " SIZE_FORMAT, 157 p2i(myThread()), myThread()->osthread()->thread_id(), 158 _target_refills, _allocation_fraction.average(), desired_size(), aligned_new_size); 159 160 set_desired_size(aligned_new_size); 161 set_refill_waste_limit(initial_refill_waste_limit()); 162 } 163 164 void ThreadLocalAllocBuffer::initialize_statistics() { 165 _number_of_refills = 0; 166 _fast_refill_waste = 0; 167 _slow_refill_waste = 0; 168 _gc_waste = 0; 169 _slow_allocations = 0; 170 } 171 172 void ThreadLocalAllocBuffer::fill(HeapWord* start, 173 HeapWord* top, 174 size_t new_size) { 175 _number_of_refills++; 176 print_stats("fill"); 177 assert(top <= start + new_size - alignment_reserve(), "size too small"); 178 179 // Remember old bytes until sample for the next tlab only if this is our first 180 // actual refill. 181 size_t old_bytes_until_sample = 0; 182 if (_number_of_refills > 1) { 183 old_bytes_until_sample = _bytes_until_sample; 184 } 185 186 initialize(start, top, start + new_size - alignment_reserve()); 187 188 if (old_bytes_until_sample > 0) { 189 set_bytes_until_sample(old_bytes_until_sample); 190 set_sample_end(); 191 } 192 193 // Reset amount of internal fragmentation 194 set_refill_waste_limit(initial_refill_waste_limit()); 195 } 196 197 void ThreadLocalAllocBuffer::initialize(HeapWord* start, 198 HeapWord* top, 199 HeapWord* end) { 200 set_start(start); 201 set_top(top); 202 set_pf_top(top); 203 set_end(end); 204 set_actual_end(end); 205 set_slow_path_end(end); 206 invariants(); 207 _bytes_until_sample = 0; 208 } 209 210 void ThreadLocalAllocBuffer::initialize() { 211 initialize(NULL, // start 212 NULL, // top 213 NULL); // end 214 215 set_desired_size(initial_desired_size()); 216 217 // Following check is needed because at startup the main 218 // thread is initialized before the heap is. The initialization for 219 // this thread is redone in startup_initialization below. 220 if (Universe::heap() != NULL) { 221 size_t capacity = Universe::heap()->tlab_capacity(myThread()) / HeapWordSize; 222 double alloc_frac = desired_size() * target_refills() / (double) capacity; 223 _allocation_fraction.sample(alloc_frac); 224 } 225 226 set_refill_waste_limit(initial_refill_waste_limit()); 227 228 initialize_statistics(); 229 } 230 231 void ThreadLocalAllocBuffer::startup_initialization() { 232 233 // Assuming each thread's active tlab is, on average, 234 // 1/2 full at a GC 235 _target_refills = 100 / (2 * TLABWasteTargetPercent); 236 _target_refills = MAX2(_target_refills, (unsigned)1U); 237 238 _global_stats = new GlobalTLABStats(); 239 240 #ifdef COMPILER2 241 // If the C2 compiler is present, extra space is needed at the end of 242 // TLABs, otherwise prefetching instructions generated by the C2 243 // compiler will fault (due to accessing memory outside of heap). 244 // The amount of space is the max of the number of lines to 245 // prefetch for array and for instance allocations. (Extra space must be 246 // reserved to accommodate both types of allocations.) 247 // 248 // Only SPARC-specific BIS instructions are known to fault. (Those 249 // instructions are generated if AllocatePrefetchStyle==3 and 250 // AllocatePrefetchInstr==1). To be on the safe side, however, 251 // extra space is reserved for all combinations of 252 // AllocatePrefetchStyle and AllocatePrefetchInstr. 253 // 254 // If the C2 compiler is not present, no space is reserved. 255 256 // +1 for rounding up to next cache line, +1 to be safe 257 if (is_server_compilation_mode_vm()) { 258 int lines = MAX2(AllocatePrefetchLines, AllocateInstancePrefetchLines) + 2; 259 _reserve_for_allocation_prefetch = (AllocatePrefetchDistance + AllocatePrefetchStepSize * lines) / 260 (int)HeapWordSize; 261 } 262 #endif 263 264 // During jvm startup, the main thread is initialized 265 // before the heap is initialized. So reinitialize it now. 266 guarantee(Thread::current()->is_Java_thread(), "tlab initialization thread not Java thread"); 267 Thread::current()->tlab().initialize(); 268 269 log_develop_trace(gc, tlab)("TLAB min: " SIZE_FORMAT " initial: " SIZE_FORMAT " max: " SIZE_FORMAT, 270 min_size(), Thread::current()->tlab().initial_desired_size(), max_size()); 271 } 272 273 size_t ThreadLocalAllocBuffer::initial_desired_size() { 274 size_t init_sz = 0; 275 276 if (TLABSize > 0) { 277 init_sz = TLABSize / HeapWordSize; 278 } else if (global_stats() != NULL) { 279 // Initial size is a function of the average number of allocating threads. 280 unsigned nof_threads = global_stats()->allocating_threads_avg(); 281 282 init_sz = (Universe::heap()->tlab_capacity(myThread()) / HeapWordSize) / 283 (nof_threads * target_refills()); 284 init_sz = align_object_size(init_sz); 285 } 286 init_sz = MIN2(MAX2(init_sz, min_size()), max_size()); 287 return init_sz; 288 } 289 290 void ThreadLocalAllocBuffer::print_stats(const char* tag) { 291 Log(gc, tlab) log; 292 if (!log.is_trace()) { 293 return; 294 } 295 296 Thread* thrd = myThread(); 297 size_t waste = _gc_waste + _slow_refill_waste + _fast_refill_waste; 298 size_t alloc = _number_of_refills * _desired_size; 299 double waste_percent = percent_of(waste, alloc); 300 size_t tlab_used = Universe::heap()->tlab_used(thrd); 301 log.trace("TLAB: %s thread: " INTPTR_FORMAT " [id: %2d]" 302 " desired_size: " SIZE_FORMAT "KB" 303 " slow allocs: %d refill waste: " SIZE_FORMAT "B" 304 " alloc:%8.5f %8.0fKB refills: %d waste %4.1f%% gc: %dB" 305 " slow: %dB fast: %dB", 306 tag, p2i(thrd), thrd->osthread()->thread_id(), 307 _desired_size / (K / HeapWordSize), 308 _slow_allocations, _refill_waste_limit * HeapWordSize, 309 _allocation_fraction.average(), 310 _allocation_fraction.average() * tlab_used / K, 311 _number_of_refills, waste_percent, 312 _gc_waste * HeapWordSize, 313 _slow_refill_waste * HeapWordSize, 314 _fast_refill_waste * HeapWordSize); 315 } 316 317 void ThreadLocalAllocBuffer::verify() { 318 HeapWord* p = start(); 319 HeapWord* t = top(); 320 HeapWord* prev_p = NULL; 321 while (p < t) { 322 oop(p)->verify(); 323 prev_p = p; 324 p += oop(p)->size(); 325 } 326 guarantee(p == top(), "end of last object must match end of space"); 327 } 328 329 void ThreadLocalAllocBuffer::set_sample_end() { 330 size_t heap_words_remaining = pointer_delta(_end, _top); 331 size_t bytes_left = _bytes_until_sample; 332 size_t words_until_sample = bytes_left / HeapWordSize; 333 334 if (heap_words_remaining > words_until_sample) { 335 HeapWord* new_end = _top + words_until_sample; 336 set_end(new_end); 337 set_slow_path_end(new_end); 338 set_bytes_until_sample(0); 339 } else { 340 bytes_left -= heap_words_remaining * HeapWordSize; 341 set_bytes_until_sample(bytes_left); 342 } 343 } 344 345 void ThreadLocalAllocBuffer::pick_next_sample(size_t overflowed_words) { 346 if (!HeapMonitoring::enabled()) { 347 return; 348 } 349 350 if (_bytes_until_sample == 0) { 351 HeapMonitoring::pick_next_sample(&_bytes_until_sample); 352 } 353 354 if (overflowed_words > 0) { 355 // Try to correct sample size by removing extra space from last allocation. 356 if (_bytes_until_sample > overflowed_words * HeapWordSize) { 357 set_bytes_until_sample(_bytes_until_sample - overflowed_words * HeapWordSize); 358 } 359 } 360 361 set_sample_end(); 362 363 log_trace(gc, tlab)("TLAB picked next sample: thread: " INTPTR_FORMAT " [id: %2d]" 364 " start: " INTPTR_FORMAT " top: " INTPTR_FORMAT " end: " INTPTR_FORMAT " actual_end:" 365 INTPTR_FORMAT " slow_path_end: " INTPTR_FORMAT, 366 p2i(myThread()), myThread()->osthread()->thread_id(), 367 p2i(start()), p2i(top()), p2i(end()), 368 p2i(_actual_end), p2i(_slow_path_end)); 369 } 370 371 Thread* ThreadLocalAllocBuffer::myThread() { 372 return (Thread*)(((char *)this) + 373 in_bytes(start_offset()) - 374 in_bytes(Thread::tlab_start_offset())); 375 } 376 377 void ThreadLocalAllocBuffer::set_back_actual_end() { 378 // Did a fast TLAB refill occur? 379 if (_slow_path_end != _end) { 380 // Fix up the actual end to be now the end of this TLAB. 381 _slow_path_end = _end; 382 _actual_end = _end; 383 } else { 384 _end = _actual_end; 385 } 386 } 387 388 void ThreadLocalAllocBuffer::handle_sample(Thread* thread, HeapWord* result, 389 size_t size) { 390 if (!HeapMonitoring::enabled()) { 391 return; 392 } 393 394 size_t size_in_bytes = size * HeapWordSize; 395 if (_bytes_until_sample > size_in_bytes) { 396 set_bytes_until_sample(_bytes_until_sample - size_in_bytes); 397 } else { 398 // Technically this is not exactly right, we probably should remember how many bytes are 399 // negative probably to then reduce our next sample size. 400 set_bytes_until_sample(0); 401 } 402 403 // Should we sample now? 404 if (should_sample()) { 405 HeapMonitoring::object_alloc_do_sample(thread, 406 reinterpret_cast<oopDesc*>(result), 407 size_in_bytes); 408 set_back_actual_end(); 409 pick_next_sample(); 410 } 411 } 412 413 HeapWord* ThreadLocalAllocBuffer::hard_end() { 414 // Did a fast TLAB refill occur? 415 if (_slow_path_end != _end) { 416 // Fix up the actual end to be now the end of this TLAB. 417 _slow_path_end = _end; 418 _actual_end = _end; 419 } 420 421 return _actual_end + alignment_reserve(); 422 } 423 424 GlobalTLABStats::GlobalTLABStats() : 425 _allocating_threads_avg(TLABAllocationWeight) { 426 427 initialize(); 428 429 _allocating_threads_avg.sample(1); // One allocating thread at startup 430 431 if (UsePerfData) { 432 433 EXCEPTION_MARK; 434 ResourceMark rm; 435 436 char* cname = PerfDataManager::counter_name("tlab", "allocThreads"); 437 _perf_allocating_threads = 438 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK); 439 440 cname = PerfDataManager::counter_name("tlab", "fills"); 441 _perf_total_refills = 442 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK); 443 444 cname = PerfDataManager::counter_name("tlab", "maxFills"); 445 _perf_max_refills = 446 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK); 447 448 cname = PerfDataManager::counter_name("tlab", "alloc"); 449 _perf_allocation = 450 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); 451 452 cname = PerfDataManager::counter_name("tlab", "gcWaste"); 453 _perf_gc_waste = 454 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); 455 456 cname = PerfDataManager::counter_name("tlab", "maxGcWaste"); 457 _perf_max_gc_waste = 458 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); 459 460 cname = PerfDataManager::counter_name("tlab", "slowWaste"); 461 _perf_slow_refill_waste = 462 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); 463 464 cname = PerfDataManager::counter_name("tlab", "maxSlowWaste"); 465 _perf_max_slow_refill_waste = 466 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); 467 468 cname = PerfDataManager::counter_name("tlab", "fastWaste"); 469 _perf_fast_refill_waste = 470 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); 471 472 cname = PerfDataManager::counter_name("tlab", "maxFastWaste"); 473 _perf_max_fast_refill_waste = 474 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); 475 476 cname = PerfDataManager::counter_name("tlab", "slowAlloc"); 477 _perf_slow_allocations = 478 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK); 479 480 cname = PerfDataManager::counter_name("tlab", "maxSlowAlloc"); 481 _perf_max_slow_allocations = 482 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK); 483 } 484 } 485 486 void GlobalTLABStats::initialize() { 487 // Clear counters summarizing info from all threads 488 _allocating_threads = 0; 489 _total_refills = 0; 490 _max_refills = 0; 491 _total_allocation = 0; 492 _total_gc_waste = 0; 493 _max_gc_waste = 0; 494 _total_slow_refill_waste = 0; 495 _max_slow_refill_waste = 0; 496 _total_fast_refill_waste = 0; 497 _max_fast_refill_waste = 0; 498 _total_slow_allocations = 0; 499 _max_slow_allocations = 0; 500 } 501 502 void GlobalTLABStats::publish() { 503 _allocating_threads_avg.sample(_allocating_threads); 504 if (UsePerfData) { 505 _perf_allocating_threads ->set_value(_allocating_threads); 506 _perf_total_refills ->set_value(_total_refills); 507 _perf_max_refills ->set_value(_max_refills); 508 _perf_allocation ->set_value(_total_allocation); 509 _perf_gc_waste ->set_value(_total_gc_waste); 510 _perf_max_gc_waste ->set_value(_max_gc_waste); 511 _perf_slow_refill_waste ->set_value(_total_slow_refill_waste); 512 _perf_max_slow_refill_waste->set_value(_max_slow_refill_waste); 513 _perf_fast_refill_waste ->set_value(_total_fast_refill_waste); 514 _perf_max_fast_refill_waste->set_value(_max_fast_refill_waste); 515 _perf_slow_allocations ->set_value(_total_slow_allocations); 516 _perf_max_slow_allocations ->set_value(_max_slow_allocations); 517 } 518 } 519 520 void GlobalTLABStats::print() { 521 Log(gc, tlab) log; 522 if (!log.is_debug()) { 523 return; 524 } 525 526 size_t waste = _total_gc_waste + _total_slow_refill_waste + _total_fast_refill_waste; 527 double waste_percent = percent_of(waste, _total_allocation); 528 log.debug("TLAB totals: thrds: %d refills: %d max: %d" 529 " slow allocs: %d max %d waste: %4.1f%%" 530 " gc: " SIZE_FORMAT "B max: " SIZE_FORMAT "B" 531 " slow: " SIZE_FORMAT "B max: " SIZE_FORMAT "B" 532 " fast: " SIZE_FORMAT "B max: " SIZE_FORMAT "B", 533 _allocating_threads, 534 _total_refills, _max_refills, 535 _total_slow_allocations, _max_slow_allocations, 536 waste_percent, 537 _total_gc_waste * HeapWordSize, 538 _max_gc_waste * HeapWordSize, 539 _total_slow_refill_waste * HeapWordSize, 540 _max_slow_refill_waste * HeapWordSize, 541 _total_fast_refill_waste * HeapWordSize, 542 _max_fast_refill_waste * HeapWordSize); 543 }