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