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 HeapWord* obj = Universe::heap()->tlab_post_allocation_setup(top()); 119 CollectedHeap::fill_with_object(obj, 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 } 127 } 128 assert(!(retire || ZeroTLAB) || 129 (start() == NULL && end() == NULL && top() == NULL), 130 "TLAB must be reset"); 131 } 132 133 void ThreadLocalAllocBuffer::resize_all_tlabs() { 134 if (ResizeTLAB) { 135 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) { 136 thread->tlab().resize(); 137 } 138 } 139 } 140 141 void ThreadLocalAllocBuffer::resize() { 142 // Compute the next tlab size using expected allocation amount 143 assert(ResizeTLAB, "Should not call this otherwise"); 144 size_t alloc = (size_t)(_allocation_fraction.average() * 145 (Universe::heap()->tlab_capacity(myThread()) / HeapWordSize)); 146 size_t new_size = alloc / _target_refills; 147 148 new_size = MIN2(MAX2(new_size, min_size()), max_size()); 149 150 size_t aligned_new_size = align_object_size(new_size); 151 152 log_trace(gc, tlab)("TLAB new size: thread: " INTPTR_FORMAT " [id: %2d]" 153 " refills %d alloc: %8.6f desired_size: " SIZE_FORMAT " -> " SIZE_FORMAT, 154 p2i(myThread()), myThread()->osthread()->thread_id(), 155 _target_refills, _allocation_fraction.average(), desired_size(), aligned_new_size); 156 157 set_desired_size(aligned_new_size); 158 set_refill_waste_limit(initial_refill_waste_limit()); 159 } 160 161 void ThreadLocalAllocBuffer::initialize_statistics() { 162 _number_of_refills = 0; 163 _fast_refill_waste = 0; 164 _slow_refill_waste = 0; 165 _gc_waste = 0; 166 _slow_allocations = 0; 167 } 168 169 void ThreadLocalAllocBuffer::fill(HeapWord* start, 170 HeapWord* top, 171 size_t new_size) { 172 _number_of_refills++; 173 print_stats("fill"); 174 assert(top <= start + new_size - alignment_reserve(), "size too small"); 175 initialize(start, top, start + new_size - alignment_reserve()); 176 177 // Reset amount of internal fragmentation 178 set_refill_waste_limit(initial_refill_waste_limit()); 179 } 180 181 void ThreadLocalAllocBuffer::initialize(HeapWord* start, 182 HeapWord* top, 183 HeapWord* end) { 184 set_start(start); 185 set_top(top); 186 set_pf_top(top); 187 set_end(end); 188 invariants(); 189 } 190 191 void ThreadLocalAllocBuffer::initialize() { 192 initialize(NULL, // start 193 NULL, // top 194 NULL); // end 195 196 set_desired_size(initial_desired_size()); 197 198 // Following check is needed because at startup the main 199 // thread is initialized before the heap is. The initialization for 200 // this thread is redone in startup_initialization below. 201 if (Universe::heap() != NULL) { 202 size_t capacity = Universe::heap()->tlab_capacity(myThread()) / HeapWordSize; 203 double alloc_frac = desired_size() * target_refills() / (double) capacity; 204 _allocation_fraction.sample(alloc_frac); 205 } 206 207 set_refill_waste_limit(initial_refill_waste_limit()); 208 209 initialize_statistics(); 210 } 211 212 void ThreadLocalAllocBuffer::startup_initialization() { 213 214 // Assuming each thread's active tlab is, on average, 215 // 1/2 full at a GC 216 _target_refills = 100 / (2 * TLABWasteTargetPercent); 217 _target_refills = MAX2(_target_refills, (unsigned)1U); 218 219 _global_stats = new GlobalTLABStats(); 220 221 #ifdef COMPILER2 222 // If the C2 compiler is present, extra space is needed at the end of 223 // TLABs, otherwise prefetching instructions generated by the C2 224 // compiler will fault (due to accessing memory outside of heap). 225 // The amount of space is the max of the number of lines to 226 // prefetch for array and for instance allocations. (Extra space must be 227 // reserved to accommodate both types of allocations.) 228 // 229 // Only SPARC-specific BIS instructions are known to fault. (Those 230 // instructions are generated if AllocatePrefetchStyle==3 and 231 // AllocatePrefetchInstr==1). To be on the safe side, however, 232 // extra space is reserved for all combinations of 233 // AllocatePrefetchStyle and AllocatePrefetchInstr. 234 // 235 // If the C2 compiler is not present, no space is reserved. 236 237 // +1 for rounding up to next cache line, +1 to be safe 238 if (is_server_compilation_mode_vm()) { 239 int lines = MAX2(AllocatePrefetchLines, AllocateInstancePrefetchLines) + 2; 240 _reserve_for_allocation_prefetch = (AllocatePrefetchDistance + AllocatePrefetchStepSize * lines) / 241 (int)HeapWordSize; 242 } 243 #endif 244 245 // During jvm startup, the main thread is initialized 246 // before the heap is initialized. So reinitialize it now. 247 guarantee(Thread::current()->is_Java_thread(), "tlab initialization thread not Java thread"); 248 Thread::current()->tlab().initialize(); 249 250 log_develop_trace(gc, tlab)("TLAB min: " SIZE_FORMAT " initial: " SIZE_FORMAT " max: " SIZE_FORMAT, 251 min_size(), Thread::current()->tlab().initial_desired_size(), max_size()); 252 } 253 254 size_t ThreadLocalAllocBuffer::initial_desired_size() { 255 size_t init_sz = 0; 256 257 if (TLABSize > 0) { 258 init_sz = TLABSize / HeapWordSize; 259 } else if (global_stats() != NULL) { 260 // Initial size is a function of the average number of allocating threads. 261 unsigned nof_threads = global_stats()->allocating_threads_avg(); 262 263 init_sz = (Universe::heap()->tlab_capacity(myThread()) / HeapWordSize) / 264 (nof_threads * target_refills()); 265 init_sz = align_object_size(init_sz); 266 } 267 init_sz = MIN2(MAX2(init_sz, min_size()), max_size()); 268 return init_sz; 269 } 270 271 void ThreadLocalAllocBuffer::print_stats(const char* tag) { 272 Log(gc, tlab) log; 273 if (!log.is_trace()) { 274 return; 275 } 276 277 Thread* thrd = myThread(); 278 size_t waste = _gc_waste + _slow_refill_waste + _fast_refill_waste; 279 size_t alloc = _number_of_refills * _desired_size; 280 double waste_percent = percent_of(waste, alloc); 281 size_t tlab_used = Universe::heap()->tlab_used(thrd); 282 log.trace("TLAB: %s thread: " INTPTR_FORMAT " [id: %2d]" 283 " desired_size: " SIZE_FORMAT "KB" 284 " slow allocs: %d refill waste: " SIZE_FORMAT "B" 285 " alloc:%8.5f %8.0fKB refills: %d waste %4.1f%% gc: %dB" 286 " slow: %dB fast: %dB", 287 tag, p2i(thrd), thrd->osthread()->thread_id(), 288 _desired_size / (K / HeapWordSize), 289 _slow_allocations, _refill_waste_limit * HeapWordSize, 290 _allocation_fraction.average(), 291 _allocation_fraction.average() * tlab_used / K, 292 _number_of_refills, waste_percent, 293 _gc_waste * HeapWordSize, 294 _slow_refill_waste * HeapWordSize, 295 _fast_refill_waste * HeapWordSize); 296 } 297 298 void ThreadLocalAllocBuffer::verify() { 299 HeapWord* p = start(); 300 HeapWord* t = top(); 301 HeapWord* prev_p = NULL; 302 while (p < t) { 303 oop(p)->verify(); 304 prev_p = p; 305 p += oop(p)->size(); 306 } 307 guarantee(p == top(), "end of last object must match end of space"); 308 } 309 310 Thread* ThreadLocalAllocBuffer::myThread() { 311 return (Thread*)(((char *)this) + 312 in_bytes(start_offset()) - 313 in_bytes(Thread::tlab_start_offset())); 314 } 315 316 317 GlobalTLABStats::GlobalTLABStats() : 318 _allocating_threads_avg(TLABAllocationWeight) { 319 320 initialize(); 321 322 _allocating_threads_avg.sample(1); // One allocating thread at startup 323 324 if (UsePerfData) { 325 326 EXCEPTION_MARK; 327 ResourceMark rm; 328 329 char* cname = PerfDataManager::counter_name("tlab", "allocThreads"); 330 _perf_allocating_threads = 331 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK); 332 333 cname = PerfDataManager::counter_name("tlab", "fills"); 334 _perf_total_refills = 335 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK); 336 337 cname = PerfDataManager::counter_name("tlab", "maxFills"); 338 _perf_max_refills = 339 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK); 340 341 cname = PerfDataManager::counter_name("tlab", "alloc"); 342 _perf_allocation = 343 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); 344 345 cname = PerfDataManager::counter_name("tlab", "gcWaste"); 346 _perf_gc_waste = 347 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); 348 349 cname = PerfDataManager::counter_name("tlab", "maxGcWaste"); 350 _perf_max_gc_waste = 351 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); 352 353 cname = PerfDataManager::counter_name("tlab", "slowWaste"); 354 _perf_slow_refill_waste = 355 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); 356 357 cname = PerfDataManager::counter_name("tlab", "maxSlowWaste"); 358 _perf_max_slow_refill_waste = 359 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); 360 361 cname = PerfDataManager::counter_name("tlab", "fastWaste"); 362 _perf_fast_refill_waste = 363 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); 364 365 cname = PerfDataManager::counter_name("tlab", "maxFastWaste"); 366 _perf_max_fast_refill_waste = 367 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK); 368 369 cname = PerfDataManager::counter_name("tlab", "slowAlloc"); 370 _perf_slow_allocations = 371 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK); 372 373 cname = PerfDataManager::counter_name("tlab", "maxSlowAlloc"); 374 _perf_max_slow_allocations = 375 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK); 376 } 377 } 378 379 void GlobalTLABStats::initialize() { 380 // Clear counters summarizing info from all threads 381 _allocating_threads = 0; 382 _total_refills = 0; 383 _max_refills = 0; 384 _total_allocation = 0; 385 _total_gc_waste = 0; 386 _max_gc_waste = 0; 387 _total_slow_refill_waste = 0; 388 _max_slow_refill_waste = 0; 389 _total_fast_refill_waste = 0; 390 _max_fast_refill_waste = 0; 391 _total_slow_allocations = 0; 392 _max_slow_allocations = 0; 393 } 394 395 void GlobalTLABStats::publish() { 396 _allocating_threads_avg.sample(_allocating_threads); 397 if (UsePerfData) { 398 _perf_allocating_threads ->set_value(_allocating_threads); 399 _perf_total_refills ->set_value(_total_refills); 400 _perf_max_refills ->set_value(_max_refills); 401 _perf_allocation ->set_value(_total_allocation); 402 _perf_gc_waste ->set_value(_total_gc_waste); 403 _perf_max_gc_waste ->set_value(_max_gc_waste); 404 _perf_slow_refill_waste ->set_value(_total_slow_refill_waste); 405 _perf_max_slow_refill_waste->set_value(_max_slow_refill_waste); 406 _perf_fast_refill_waste ->set_value(_total_fast_refill_waste); 407 _perf_max_fast_refill_waste->set_value(_max_fast_refill_waste); 408 _perf_slow_allocations ->set_value(_total_slow_allocations); 409 _perf_max_slow_allocations ->set_value(_max_slow_allocations); 410 } 411 } 412 413 void GlobalTLABStats::print() { 414 Log(gc, tlab) log; 415 if (!log.is_debug()) { 416 return; 417 } 418 419 size_t waste = _total_gc_waste + _total_slow_refill_waste + _total_fast_refill_waste; 420 double waste_percent = percent_of(waste, _total_allocation); 421 log.debug("TLAB totals: thrds: %d refills: %d max: %d" 422 " slow allocs: %d max %d waste: %4.1f%%" 423 " gc: " SIZE_FORMAT "B max: " SIZE_FORMAT "B" 424 " slow: " SIZE_FORMAT "B max: " SIZE_FORMAT "B" 425 " fast: " SIZE_FORMAT "B max: " SIZE_FORMAT "B", 426 _allocating_threads, 427 _total_refills, _max_refills, 428 _total_slow_allocations, _max_slow_allocations, 429 waste_percent, 430 _total_gc_waste * HeapWordSize, 431 _max_gc_waste * HeapWordSize, 432 _total_slow_refill_waste * HeapWordSize, 433 _max_slow_refill_waste * HeapWordSize, 434 _total_fast_refill_waste * HeapWordSize, 435 _max_fast_refill_waste * HeapWordSize); 436 }