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