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 "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 (JavaThread *thread = Threads::first(); thread != NULL; thread = thread->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 set_actual_end(NULL);
126 set_slow_path_end(NULL);
127 }
128 }
129 assert(!(retire || ZeroTLAB) ||
130 (start() == NULL && end() == NULL && top() == NULL &&
131 actual_end() == NULL && slow_path_end() == NULL),
132 "TLAB must be reset");
133 }
134
135 void ThreadLocalAllocBuffer::resize_all_tlabs() {
136 if (ResizeTLAB) {
137 for (JavaThread *thread = Threads::first(); thread != NULL; thread = thread->next()) {
138 thread->tlab().resize();
139 }
140 }
141 }
142
143 void ThreadLocalAllocBuffer::resize() {
144 // Compute the next tlab size using expected allocation amount
145 assert(ResizeTLAB, "Should not call this otherwise");
146 size_t alloc = (size_t)(_allocation_fraction.average() *
147 (Universe::heap()->tlab_capacity(myThread()) / HeapWordSize));
148 size_t new_size = alloc / _target_refills;
149
150 new_size = MIN2(MAX2(new_size, min_size()), max_size());
151
152 size_t aligned_new_size = align_object_size(new_size);
153
154 log_trace(gc, tlab)("TLAB new size: thread: " INTPTR_FORMAT " [id: %2d]"
155 " refills %d alloc: %8.6f desired_size: " SIZE_FORMAT " -> " SIZE_FORMAT,
156 p2i(myThread()), myThread()->osthread()->thread_id(),
157 _target_refills, _allocation_fraction.average(), desired_size(), aligned_new_size);
158
159 set_desired_size(aligned_new_size);
160 set_refill_waste_limit(initial_refill_waste_limit());
161 }
162
163 void ThreadLocalAllocBuffer::initialize_statistics() {
164 _number_of_refills = 0;
165 _fast_refill_waste = 0;
166 _slow_refill_waste = 0;
167 _gc_waste = 0;
168 _slow_allocations = 0;
169 }
170
171 void ThreadLocalAllocBuffer::fill(HeapWord* start,
172 HeapWord* top,
173 size_t new_size) {
174 _number_of_refills++;
175 print_stats("fill");
176 assert(top <= start + new_size - alignment_reserve(), "size too small");
177
178 // Remember old bytes until sample for the next tlab only if this is our first
179 // actual refill.
180 size_t old_bytes_until_sample = 0;
181 if (_number_of_refills > 1) {
182 old_bytes_until_sample = bytes_until_sample();
183 }
184
185 initialize(start, top, start + new_size - alignment_reserve());
186
187 if (old_bytes_until_sample > 0) {
188 set_bytes_until_sample(old_bytes_until_sample);
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_end(end);
203 set_actual_end(end);
204 set_slow_path_end(end);
205 invariants();
206 _bytes_until_sample = 0;
207 }
208
209 void ThreadLocalAllocBuffer::initialize() {
210 initialize(NULL, // start
211 NULL, // top
212 NULL); // end
213
214 set_desired_size(initial_desired_size());
215
216 // Following check is needed because at startup the main (primordial)
217 // thread is initialized before the heap is. The initialization for
218 // this thread is redone in startup_initialization below.
219 if (Universe::heap() != NULL) {
220 size_t capacity = Universe::heap()->tlab_capacity(myThread()) / HeapWordSize;
221 double alloc_frac = desired_size() * target_refills() / (double) capacity;
222 _allocation_fraction.sample(alloc_frac);
223 }
224
225 set_refill_waste_limit(initial_refill_waste_limit());
226
227 initialize_statistics();
228 }
229
230 void ThreadLocalAllocBuffer::startup_initialization() {
231
232 // Assuming each thread's active tlab is, on average,
233 // 1/2 full at a GC
234 _target_refills = 100 / (2 * TLABWasteTargetPercent);
235 _target_refills = MAX2(_target_refills, (unsigned)1U);
236
237 _global_stats = new GlobalTLABStats();
238
239 #ifdef COMPILER2
240 // If the C2 compiler is present, extra space is needed at the end of
241 // TLABs, otherwise prefetching instructions generated by the C2
242 // compiler will fault (due to accessing memory outside of heap).
243 // The amount of space is the max of the number of lines to
244 // prefetch for array and for instance allocations. (Extra space must be
245 // reserved to accommodate both types of allocations.)
246 //
247 // Only SPARC-specific BIS instructions are known to fault. (Those
248 // instructions are generated if AllocatePrefetchStyle==3 and
249 // AllocatePrefetchInstr==1). To be on the safe side, however,
250 // extra space is reserved for all combinations of
251 // AllocatePrefetchStyle and AllocatePrefetchInstr.
252 //
253 // If the C2 compiler is not present, no space is reserved.
254
255 // +1 for rounding up to next cache line, +1 to be safe
256 if (is_server_compilation_mode_vm()) {
257 int lines = MAX2(AllocatePrefetchLines, AllocateInstancePrefetchLines) + 2;
258 _reserve_for_allocation_prefetch = (AllocatePrefetchDistance + AllocatePrefetchStepSize * lines) /
259 (int)HeapWordSize;
260 }
261 #endif
262
263 // During jvm startup, the main (primordial) thread is initialized
264 // before the heap is initialized. So reinitialize it now.
265 guarantee(Thread::current()->is_Java_thread(), "tlab initialization thread not Java thread");
266 Thread::current()->tlab().initialize();
267
268 log_develop_trace(gc, tlab)("TLAB min: " SIZE_FORMAT " initial: " SIZE_FORMAT " max: " SIZE_FORMAT,
269 min_size(), Thread::current()->tlab().initial_desired_size(), max_size());
270 }
271
272 size_t ThreadLocalAllocBuffer::initial_desired_size() {
273 size_t init_sz = 0;
274
275 if (TLABSize > 0) {
276 init_sz = TLABSize / HeapWordSize;
277 } else if (global_stats() != NULL) {
278 // Initial size is a function of the average number of allocating threads.
279 unsigned nof_threads = global_stats()->allocating_threads_avg();
280
281 init_sz = (Universe::heap()->tlab_capacity(myThread()) / HeapWordSize) /
282 (nof_threads * target_refills());
283 init_sz = align_object_size(init_sz);
284 }
285 init_sz = MIN2(MAX2(init_sz, min_size()), max_size());
286 return init_sz;
287 }
288
289 void ThreadLocalAllocBuffer::print_stats(const char* tag) {
290 Log(gc, tlab) log;
291 if (!log.is_trace()) {
292 return;
293 }
294
295 Thread* thrd = myThread();
296 size_t waste = _gc_waste + _slow_refill_waste + _fast_refill_waste;
297 size_t alloc = _number_of_refills * _desired_size;
298 double waste_percent = percent_of(waste, alloc);
299 size_t tlab_used = Universe::heap()->tlab_used(thrd);
300 log.trace("TLAB: %s thread: " INTPTR_FORMAT " [id: %2d]"
301 " desired_size: " SIZE_FORMAT "KB"
302 " slow allocs: %d refill waste: " SIZE_FORMAT "B"
303 " alloc:%8.5f %8.0fKB refills: %d waste %4.1f%% gc: %dB"
304 " slow: %dB fast: %dB",
305 tag, p2i(thrd), thrd->osthread()->thread_id(),
306 _desired_size / (K / HeapWordSize),
307 _slow_allocations, _refill_waste_limit * HeapWordSize,
308 _allocation_fraction.average(),
309 _allocation_fraction.average() * tlab_used / K,
310 _number_of_refills, waste_percent,
311 _gc_waste * HeapWordSize,
312 _slow_refill_waste * HeapWordSize,
313 _fast_refill_waste * HeapWordSize);
314 }
315
316 void ThreadLocalAllocBuffer::verify() {
317 HeapWord* p = start();
318 HeapWord* t = top();
319 HeapWord* prev_p = NULL;
320 while (p < t) {
321 oop(p)->verify();
322 prev_p = p;
323 p += oop(p)->size();
324 }
325 guarantee(p == top(), "end of last object must match end of space");
326 }
327
328 void ThreadLocalAllocBuffer::set_sample_end() {
329 size_t heap_words_remaining = _end - _top;
330 size_t bytes_left = bytes_until_sample();
331 size_t words_until_sample = bytes_left / HeapWordSize;
332
333 if (heap_words_remaining > words_until_sample) {
334 HeapWord* new_end = _top + words_until_sample;
335 set_end(new_end);
336 set_slow_path_end(new_end);
337 set_bytes_until_sample(0);
338 } else {
339 bytes_left -= heap_words_remaining * HeapWordSize;
340 set_bytes_until_sample(bytes_left);
341 }
342 }
343
344 void ThreadLocalAllocBuffer::pick_next_sample(size_t diff) {
345 if (!HeapMonitoring::enabled()) {
346 return;
347 }
348
349 if (bytes_until_sample() == 0) {
350 HeapMonitoring::pick_next_sample(bytes_until_sample_addr());
351 }
352
353 if (diff > 0) {
354 // Try to correct sample size by removing extra space from last allocation.
355 if (bytes_until_sample() > diff * HeapWordSize) {
356 set_bytes_until_sample(bytes_until_sample() - diff * HeapWordSize);
357 }
358 }
359
360 set_sample_end();
361
362 log_trace(gc, tlab)("TLAB picked next sample: thread: " INTPTR_FORMAT " [id: %2d]"
363 " start: %p top: %p end: %p actual_end: %p slow_path_end: %p",
364 p2i(myThread()), myThread()->osthread()->thread_id(),
365 start(), top(), end(),
366 actual_end(), slow_path_end());
367 }
368
369 Thread* ThreadLocalAllocBuffer::myThread() {
370 return (Thread*)(((char *)this) +
371 in_bytes(start_offset()) -
372 in_bytes(Thread::tlab_start_offset()));
373 }
374
375 void ThreadLocalAllocBuffer::set_back_actual_end() {
376 // Did a fast TLAB refill occur?
377 if (_slow_path_end != _end) {
378 // Fix up the actual end to be now the end of this TLAB.
379 _slow_path_end = _end;
380 _actual_end = _end;
381 } else {
382 _end = _actual_end;
383 }
384 }
385
386 void ThreadLocalAllocBuffer::handle_sample(Thread* thread, HeapWord* result,
387 size_t size) {
388 if (!HeapMonitoring::enabled()) {
389 return;
390 }
391
392 size_t size_in_bytes = size * HeapWordSize;
393 if (bytes_until_sample() > size_in_bytes) {
394 set_bytes_until_sample(bytes_until_sample() - size_in_bytes);
395 } else {
396 // Technically this is not exactly right, we probably should remember how many bytes are
397 // negative probably to then reduce our next sample size.
398 set_bytes_until_sample(0);
399 }
400
401 // Should we sample now?
402 if (should_sample()) {
403 HeapMonitoring::object_alloc_do_sample(thread,
404 reinterpret_cast<oopDesc*>(result),
405 size_in_bytes);
406 set_back_actual_end();
407 pick_next_sample();
408 }
409 }
410
411 HeapWord* ThreadLocalAllocBuffer::hard_end() {
412 // Did a fast TLAB refill occur?
413 if (_slow_path_end != _end) {
414 // Fix up the actual end to be now the end of this TLAB.
415 _slow_path_end = _end;
416 _actual_end = _end;
417 }
418
419 return _actual_end + alignment_reserve();
420 }
421 GlobalTLABStats::GlobalTLABStats() :
422 _allocating_threads_avg(TLABAllocationWeight) {
423
424 initialize();
425
426 _allocating_threads_avg.sample(1); // One allocating thread at startup
427
428 if (UsePerfData) {
429
430 EXCEPTION_MARK;
431 ResourceMark rm;
432
433 char* cname = PerfDataManager::counter_name("tlab", "allocThreads");
434 _perf_allocating_threads =
435 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
436
437 cname = PerfDataManager::counter_name("tlab", "fills");
438 _perf_total_refills =
439 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
440
441 cname = PerfDataManager::counter_name("tlab", "maxFills");
442 _perf_max_refills =
443 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
444
445 cname = PerfDataManager::counter_name("tlab", "alloc");
446 _perf_allocation =
447 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
448
449 cname = PerfDataManager::counter_name("tlab", "gcWaste");
450 _perf_gc_waste =
451 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
452
453 cname = PerfDataManager::counter_name("tlab", "maxGcWaste");
454 _perf_max_gc_waste =
455 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
456
457 cname = PerfDataManager::counter_name("tlab", "slowWaste");
458 _perf_slow_refill_waste =
459 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
460
461 cname = PerfDataManager::counter_name("tlab", "maxSlowWaste");
462 _perf_max_slow_refill_waste =
463 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
464
465 cname = PerfDataManager::counter_name("tlab", "fastWaste");
466 _perf_fast_refill_waste =
467 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
468
469 cname = PerfDataManager::counter_name("tlab", "maxFastWaste");
470 _perf_max_fast_refill_waste =
471 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
472
473 cname = PerfDataManager::counter_name("tlab", "slowAlloc");
474 _perf_slow_allocations =
475 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
476
477 cname = PerfDataManager::counter_name("tlab", "maxSlowAlloc");
478 _perf_max_slow_allocations =
479 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
480 }
481 }
482
483 void GlobalTLABStats::initialize() {
484 // Clear counters summarizing info from all threads
485 _allocating_threads = 0;
486 _total_refills = 0;
487 _max_refills = 0;
488 _total_allocation = 0;
489 _total_gc_waste = 0;
490 _max_gc_waste = 0;
491 _total_slow_refill_waste = 0;
492 _max_slow_refill_waste = 0;
493 _total_fast_refill_waste = 0;
494 _max_fast_refill_waste = 0;
495 _total_slow_allocations = 0;
496 _max_slow_allocations = 0;
497 }
498
499 void GlobalTLABStats::publish() {
500 _allocating_threads_avg.sample(_allocating_threads);
501 if (UsePerfData) {
502 _perf_allocating_threads ->set_value(_allocating_threads);
503 _perf_total_refills ->set_value(_total_refills);
504 _perf_max_refills ->set_value(_max_refills);
505 _perf_allocation ->set_value(_total_allocation);
506 _perf_gc_waste ->set_value(_total_gc_waste);
507 _perf_max_gc_waste ->set_value(_max_gc_waste);
508 _perf_slow_refill_waste ->set_value(_total_slow_refill_waste);
509 _perf_max_slow_refill_waste->set_value(_max_slow_refill_waste);
510 _perf_fast_refill_waste ->set_value(_total_fast_refill_waste);
511 _perf_max_fast_refill_waste->set_value(_max_fast_refill_waste);
512 _perf_slow_allocations ->set_value(_total_slow_allocations);
513 _perf_max_slow_allocations ->set_value(_max_slow_allocations);
514 }
515 }
516
517 void GlobalTLABStats::print() {
518 Log(gc, tlab) log;
519 if (!log.is_debug()) {
520 return;
521 }
522
523 size_t waste = _total_gc_waste + _total_slow_refill_waste + _total_fast_refill_waste;
524 double waste_percent = percent_of(waste, _total_allocation);
525 log.debug("TLAB totals: thrds: %d refills: %d max: %d"
526 " slow allocs: %d max %d waste: %4.1f%%"
527 " gc: " SIZE_FORMAT "B max: " SIZE_FORMAT "B"
528 " slow: " SIZE_FORMAT "B max: " SIZE_FORMAT "B"
529 " fast: " SIZE_FORMAT "B max: " SIZE_FORMAT "B",
530 _allocating_threads,
531 _total_refills, _max_refills,
532 _total_slow_allocations, _max_slow_allocations,
533 waste_percent,
534 _total_gc_waste * HeapWordSize,
535 _max_gc_waste * HeapWordSize,
536 _total_slow_refill_waste * HeapWordSize,
537 _max_slow_refill_waste * HeapWordSize,
538 _total_fast_refill_waste * HeapWordSize,
539 _max_fast_refill_waste * HeapWordSize);
540 }