1 /*
2 * Copyright (c) 1999, 2018, 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.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 size_t ThreadLocalAllocBuffer::remaining() {
50 if (current_end() == NULL) {
51 return 0;
52 }
53
54 return pointer_delta(reserved_end(), top());
55 }
56
57 void ThreadLocalAllocBuffer::accumulate_statistics_before_gc() {
58 global_stats()->initialize();
59
60 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
61 thread->tlab().accumulate_statistics();
62 thread->tlab().initialize_statistics();
63 }
64
65 // Publish new stats if some allocation occurred.
66 if (global_stats()->allocation() != 0) {
67 global_stats()->publish();
68 global_stats()->print();
69 }
70 }
71
72 void ThreadLocalAllocBuffer::accumulate_statistics() {
73 Thread* thread = myThread();
74 size_t capacity = Universe::heap()->tlab_capacity(thread);
75 size_t used = Universe::heap()->tlab_used(thread);
76
77 _gc_waste += (unsigned)remaining();
78 size_t total_allocated = thread->allocated_bytes();
79 size_t allocated_since_last_gc = total_allocated - _allocated_before_last_gc;
80 _allocated_before_last_gc = total_allocated;
81
82 print_stats("gc");
83
84 if (_number_of_refills > 0) {
85 // Update allocation history if a reasonable amount of eden was allocated.
86 bool update_allocation_history = used > 0.5 * capacity;
87
88 if (update_allocation_history) {
89 // Average the fraction of eden allocated in a tlab by this
90 // thread for use in the next resize operation.
91 // _gc_waste is not subtracted because it's included in
92 // "used".
93 // The result can be larger than 1.0 due to direct to old allocations.
94 // These allocations should ideally not be counted but since it is not possible
95 // to filter them out here we just cap the fraction to be at most 1.0.
96 double alloc_frac = MIN2(1.0, (double) allocated_since_last_gc / used);
97 _allocation_fraction.sample(alloc_frac);
98 }
99 global_stats()->update_allocating_threads();
100 global_stats()->update_number_of_refills(_number_of_refills);
101 global_stats()->update_allocation(_number_of_refills * desired_size());
102 global_stats()->update_gc_waste(_gc_waste);
103 global_stats()->update_slow_refill_waste(_slow_refill_waste);
104 global_stats()->update_fast_refill_waste(_fast_refill_waste);
105
106 } else {
107 assert(_number_of_refills == 0 && _fast_refill_waste == 0 &&
108 _slow_refill_waste == 0 && _gc_waste == 0,
109 "tlab stats == 0");
110 }
111 global_stats()->update_slow_allocations(_slow_allocations);
112 }
113
114 // Fills the current tlab with a dummy filler array to create
115 // an illusion of a contiguous Eden and optionally retires the tlab.
116 // Waste accounting should be done in caller as appropriate; see,
117 // for example, clear_before_allocation().
118 void ThreadLocalAllocBuffer::make_parsable(bool retire, bool zap) {
119 if (current_end() != NULL) {
120 invariants();
121
122 if (retire) {
123 myThread()->incr_allocated_bytes(used_bytes());
124 }
125
126 CollectedHeap::fill_with_object(top(), reserved_end(), retire && zap);
127
128 if (retire || ZeroTLAB) { // "Reset" the TLAB
129 set_start(NULL);
130 set_top(NULL);
131 set_pf_top(NULL);
132 set_current_end(NULL);
133 set_allocation_end(NULL);
134 }
135 }
136 assert(!(retire || ZeroTLAB) ||
137 (start() == NULL && current_end() == NULL && top() == NULL &&
138 _allocation_end == NULL),
139 "TLAB must be reset");
140 }
141
142 void ThreadLocalAllocBuffer::resize_all_tlabs() {
143 if (ResizeTLAB) {
144 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
145 thread->tlab().resize();
146 }
147 }
148 }
149
150 void ThreadLocalAllocBuffer::resize() {
151 // Compute the next tlab size using expected allocation amount
152 assert(ResizeTLAB, "Should not call this otherwise");
153 size_t alloc = (size_t)(_allocation_fraction.average() *
154 (Universe::heap()->tlab_capacity(myThread()) / HeapWordSize));
155 size_t new_size = alloc / _target_refills;
156
157 new_size = MIN2(MAX2(new_size, min_size()), max_size());
158
159 size_t aligned_new_size = align_object_size(new_size);
160
161 log_trace(gc, tlab)("TLAB new size: thread: " INTPTR_FORMAT " [id: %2d]"
162 " refills %d alloc: %8.6f desired_size: " SIZE_FORMAT " -> " SIZE_FORMAT,
163 p2i(myThread()), myThread()->osthread()->thread_id(),
164 _target_refills, _allocation_fraction.average(), desired_size(), aligned_new_size);
165
166 set_desired_size(aligned_new_size);
167 set_refill_waste_limit(initial_refill_waste_limit());
168 }
169
170 void ThreadLocalAllocBuffer::initialize_statistics() {
171 _number_of_refills = 0;
172 _fast_refill_waste = 0;
173 _slow_refill_waste = 0;
174 _gc_waste = 0;
175 _slow_allocations = 0;
176 }
177
178 void ThreadLocalAllocBuffer::fill(HeapWord* start,
179 HeapWord* top,
180 size_t new_size) {
181 _number_of_refills++;
182 print_stats("fill");
183 assert(top <= start + new_size - alignment_reserve(), "size too small");
184
185 initialize(start, top, start + new_size - alignment_reserve());
186
187 if (ThreadHeapSampler::enabled()) {
188 set_sample_end();
189 }
190
191 // Reset amount of internal fragmentation
192 set_refill_waste_limit(initial_refill_waste_limit());
193 }
194
195 void ThreadLocalAllocBuffer::initialize(HeapWord* start,
196 HeapWord* top,
197 HeapWord* end) {
198 set_start(start);
199 set_top(top);
200 set_pf_top(top);
201 set_current_end(end);
202 set_allocation_end(end);
203 invariants();
204 }
205
206 void ThreadLocalAllocBuffer::initialize() {
207 initialize(NULL, // start
208 NULL, // top
209 NULL); // end
210
211 set_desired_size(initial_desired_size());
212
213 // Following check is needed because at startup the main
214 // thread is initialized before the heap is. The initialization for
215 // this thread is redone in startup_initialization below.
216 if (Universe::heap() != NULL) {
217 size_t capacity = Universe::heap()->tlab_capacity(myThread()) / HeapWordSize;
218 double alloc_frac = desired_size() * target_refills() / (double) capacity;
219 _allocation_fraction.sample(alloc_frac);
220 }
221
222 set_refill_waste_limit(initial_refill_waste_limit());
223
224 initialize_statistics();
225 }
226
227 void ThreadLocalAllocBuffer::startup_initialization() {
228
229 // Assuming each thread's active tlab is, on average,
230 // 1/2 full at a GC
231 _target_refills = 100 / (2 * TLABWasteTargetPercent);
232 _target_refills = MAX2(_target_refills, (unsigned)1U);
233
234 _global_stats = new GlobalTLABStats();
235
236 #ifdef COMPILER2
237 // If the C2 compiler is present, extra space is needed at the end of
238 // TLABs, otherwise prefetching instructions generated by the C2
239 // compiler will fault (due to accessing memory outside of heap).
240 // The amount of space is the max of the number of lines to
241 // prefetch for array and for instance allocations. (Extra space must be
242 // reserved to accommodate both types of allocations.)
243 //
244 // Only SPARC-specific BIS instructions are known to fault. (Those
245 // instructions are generated if AllocatePrefetchStyle==3 and
246 // AllocatePrefetchInstr==1). To be on the safe side, however,
247 // extra space is reserved for all combinations of
248 // AllocatePrefetchStyle and AllocatePrefetchInstr.
249 //
250 // If the C2 compiler is not present, no space is reserved.
251
252 // +1 for rounding up to next cache line, +1 to be safe
253 if (is_server_compilation_mode_vm()) {
254 int lines = MAX2(AllocatePrefetchLines, AllocateInstancePrefetchLines) + 2;
255 _reserve_for_allocation_prefetch = (AllocatePrefetchDistance + AllocatePrefetchStepSize * lines) /
256 (int)HeapWordSize;
257 }
258 #endif
259
260 // During jvm startup, the main thread is initialized
261 // before the heap is initialized. So reinitialize it now.
262 guarantee(Thread::current()->is_Java_thread(), "tlab initialization thread not Java thread");
263 Thread::current()->tlab().initialize();
264
265 log_develop_trace(gc, tlab)("TLAB min: " SIZE_FORMAT " initial: " SIZE_FORMAT " max: " SIZE_FORMAT,
266 min_size(), Thread::current()->tlab().initial_desired_size(), max_size());
267 }
268
269 size_t ThreadLocalAllocBuffer::initial_desired_size() {
270 size_t init_sz = 0;
271
272 if (TLABSize > 0) {
273 init_sz = TLABSize / HeapWordSize;
274 } else if (global_stats() != NULL) {
275 // Initial size is a function of the average number of allocating threads.
276 unsigned nof_threads = global_stats()->allocating_threads_avg();
277
278 init_sz = (Universe::heap()->tlab_capacity(myThread()) / HeapWordSize) /
279 (nof_threads * target_refills());
280 init_sz = align_object_size(init_sz);
281 }
282 init_sz = MIN2(MAX2(init_sz, min_size()), max_size());
283 return init_sz;
284 }
285
286 void ThreadLocalAllocBuffer::print_stats(const char* tag) {
287 Log(gc, tlab) log;
288 if (!log.is_trace()) {
289 return;
290 }
291
292 Thread* thrd = myThread();
293 size_t waste = _gc_waste + _slow_refill_waste + _fast_refill_waste;
294 size_t alloc = _number_of_refills * _desired_size;
295 double waste_percent = percent_of(waste, alloc);
296 size_t tlab_used = Universe::heap()->tlab_used(thrd);
297 log.trace("TLAB: %s thread: " INTPTR_FORMAT " [id: %2d]"
298 " desired_size: " SIZE_FORMAT "KB"
299 " slow allocs: %d refill waste: " SIZE_FORMAT "B"
300 " alloc:%8.5f %8.0fKB refills: %d waste %4.1f%% gc: %dB"
301 " slow: %dB fast: %dB",
302 tag, p2i(thrd), thrd->osthread()->thread_id(),
303 _desired_size / (K / HeapWordSize),
304 _slow_allocations, _refill_waste_limit * HeapWordSize,
305 _allocation_fraction.average(),
306 _allocation_fraction.average() * tlab_used / K,
307 _number_of_refills, waste_percent,
308 _gc_waste * HeapWordSize,
309 _slow_refill_waste * HeapWordSize,
310 _fast_refill_waste * HeapWordSize);
311 }
312
313 void ThreadLocalAllocBuffer::verify() {
314 HeapWord* p = start();
315 HeapWord* t = top();
316 HeapWord* prev_p = NULL;
317 while (p < t) {
318 oop(p)->verify();
319 prev_p = p;
320 p += oop(p)->size();
321 }
322 guarantee(p == top(), "end of last object must match end of space");
323 }
324
325 void ThreadLocalAllocBuffer::set_sample_end() {
326 size_t heap_words_remaining = pointer_delta(_current_end, _top);
327 size_t bytes_until_sample = myThread()->heap_sampler().bytes_until_sample();
328 size_t words_until_sample = bytes_until_sample / HeapWordSize;;
329
330 if (heap_words_remaining > words_until_sample) {
331 HeapWord* new_end = _top + words_until_sample;
332 set_current_end(new_end);
333 _bytes_since_last_sample_point = bytes_until_sample;
334 } else {
335 _bytes_since_last_sample_point = heap_words_remaining * HeapWordSize;;
336 }
337 }
338
339 Thread* ThreadLocalAllocBuffer::myThread() {
340 return (Thread*)(((char *)this) +
341 in_bytes(start_offset()) -
342 in_bytes(Thread::tlab_start_offset()));
343 }
344
345 void ThreadLocalAllocBuffer::set_back_allocation_end() {
346 _current_end = _allocation_end;
347 }
348
349 HeapWord* ThreadLocalAllocBuffer::allocate_sampled_object(size_t size) {
350 Thread* thread = myThread();
351 thread->tlab().set_back_allocation_end();
352 HeapWord* result = thread->tlab().allocate(size);
353
354 if (result) {
355 thread->heap_sampler().check_for_sampling(result, size * HeapWordSize, _bytes_since_last_sample_point);
356 thread->tlab().set_sample_end();
357 }
358
359 return result;
360 }
361
362 HeapWord* ThreadLocalAllocBuffer::reserved_end() {
363 return _allocation_end + alignment_reserve();
364 }
365
366 GlobalTLABStats::GlobalTLABStats() :
367 _allocating_threads_avg(TLABAllocationWeight) {
368
369 initialize();
370
371 _allocating_threads_avg.sample(1); // One allocating thread at startup
372
373 if (UsePerfData) {
374
375 EXCEPTION_MARK;
376 ResourceMark rm;
377
378 char* cname = PerfDataManager::counter_name("tlab", "allocThreads");
379 _perf_allocating_threads =
380 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
381
382 cname = PerfDataManager::counter_name("tlab", "fills");
383 _perf_total_refills =
384 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
385
386 cname = PerfDataManager::counter_name("tlab", "maxFills");
387 _perf_max_refills =
388 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
389
390 cname = PerfDataManager::counter_name("tlab", "alloc");
391 _perf_allocation =
392 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
393
394 cname = PerfDataManager::counter_name("tlab", "gcWaste");
395 _perf_gc_waste =
396 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
397
398 cname = PerfDataManager::counter_name("tlab", "maxGcWaste");
399 _perf_max_gc_waste =
400 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
401
402 cname = PerfDataManager::counter_name("tlab", "slowWaste");
403 _perf_slow_refill_waste =
404 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
405
406 cname = PerfDataManager::counter_name("tlab", "maxSlowWaste");
407 _perf_max_slow_refill_waste =
408 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
409
410 cname = PerfDataManager::counter_name("tlab", "fastWaste");
411 _perf_fast_refill_waste =
412 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
413
414 cname = PerfDataManager::counter_name("tlab", "maxFastWaste");
415 _perf_max_fast_refill_waste =
416 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
417
418 cname = PerfDataManager::counter_name("tlab", "slowAlloc");
419 _perf_slow_allocations =
420 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
421
422 cname = PerfDataManager::counter_name("tlab", "maxSlowAlloc");
423 _perf_max_slow_allocations =
424 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
425 }
426 }
427
428 void GlobalTLABStats::initialize() {
429 // Clear counters summarizing info from all threads
430 _allocating_threads = 0;
431 _total_refills = 0;
432 _max_refills = 0;
433 _total_allocation = 0;
434 _total_gc_waste = 0;
435 _max_gc_waste = 0;
436 _total_slow_refill_waste = 0;
437 _max_slow_refill_waste = 0;
438 _total_fast_refill_waste = 0;
439 _max_fast_refill_waste = 0;
440 _total_slow_allocations = 0;
441 _max_slow_allocations = 0;
442 }
443
444 void GlobalTLABStats::publish() {
445 _allocating_threads_avg.sample(_allocating_threads);
446 if (UsePerfData) {
447 _perf_allocating_threads ->set_value(_allocating_threads);
448 _perf_total_refills ->set_value(_total_refills);
449 _perf_max_refills ->set_value(_max_refills);
450 _perf_allocation ->set_value(_total_allocation);
451 _perf_gc_waste ->set_value(_total_gc_waste);
452 _perf_max_gc_waste ->set_value(_max_gc_waste);
453 _perf_slow_refill_waste ->set_value(_total_slow_refill_waste);
454 _perf_max_slow_refill_waste->set_value(_max_slow_refill_waste);
455 _perf_fast_refill_waste ->set_value(_total_fast_refill_waste);
456 _perf_max_fast_refill_waste->set_value(_max_fast_refill_waste);
457 _perf_slow_allocations ->set_value(_total_slow_allocations);
458 _perf_max_slow_allocations ->set_value(_max_slow_allocations);
459 }
460 }
461
462 void GlobalTLABStats::print() {
463 Log(gc, tlab) log;
464 if (!log.is_debug()) {
465 return;
466 }
467
468 size_t waste = _total_gc_waste + _total_slow_refill_waste + _total_fast_refill_waste;
469 double waste_percent = percent_of(waste, _total_allocation);
470 log.debug("TLAB totals: thrds: %d refills: %d max: %d"
471 " slow allocs: %d max %d waste: %4.1f%%"
472 " gc: " SIZE_FORMAT "B max: " SIZE_FORMAT "B"
473 " slow: " SIZE_FORMAT "B max: " SIZE_FORMAT "B"
474 " fast: " SIZE_FORMAT "B max: " SIZE_FORMAT "B",
475 _allocating_threads,
476 _total_refills, _max_refills,
477 _total_slow_allocations, _max_slow_allocations,
478 waste_percent,
479 _total_gc_waste * HeapWordSize,
480 _max_gc_waste * HeapWordSize,
481 _total_slow_refill_waste * HeapWordSize,
482 _max_slow_refill_waste * HeapWordSize,
483 _total_fast_refill_waste * HeapWordSize,
484 _max_fast_refill_waste * HeapWordSize);
485 }