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/collectedHeap.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 size_t ThreadLocalAllocBuffer::_max_size = 0;
37 int ThreadLocalAllocBuffer::_reserve_for_allocation_prefetch = 0;
38 unsigned int ThreadLocalAllocBuffer::_target_refills = 0;
39
40 size_t ThreadLocalAllocBuffer::remaining() {
41 if (end() == NULL) {
42 return 0;
43 }
44
45 return pointer_delta(hard_end(), top());
46 }
47
48 void ThreadLocalAllocBuffer::accumulate_and_reset_statistics(ThreadLocalAllocStats* stats) {
49 Thread* thr = thread();
50 size_t capacity = Universe::heap()->tlab_capacity(thr);
51 size_t used = Universe::heap()->tlab_used(thr);
52
53 _gc_waste += (unsigned)remaining();
54 size_t total_allocated = thr->allocated_bytes();
55 size_t allocated_since_last_gc = total_allocated - _allocated_before_last_gc;
56 _allocated_before_last_gc = total_allocated;
57
58 print_stats("gc");
59
60 if (_number_of_refills > 0) {
61 // Update allocation history if a reasonable amount of eden was allocated.
62 bool update_allocation_history = used > 0.5 * capacity;
63
64 if (update_allocation_history) {
65 // Average the fraction of eden allocated in a tlab by this
66 // thread for use in the next resize operation.
67 // _gc_waste is not subtracted because it's included in
68 // "used".
69 // The result can be larger than 1.0 due to direct to old allocations.
70 // These allocations should ideally not be counted but since it is not possible
71 // to filter them out here we just cap the fraction to be at most 1.0.
72 double alloc_frac = MIN2(1.0, (double) allocated_since_last_gc / used);
73 _allocation_fraction.sample(alloc_frac);
74 }
75
76 stats->update_fast_allocations(_number_of_refills,
77 _allocated_size,
78 _gc_waste,
79 _fast_refill_waste,
80 _slow_refill_waste);
81 } else {
82 assert(_number_of_refills == 0 && _fast_refill_waste == 0 &&
83 _slow_refill_waste == 0 && _gc_waste == 0,
84 "tlab stats == 0");
85 }
86
87 stats->update_slow_allocations(_slow_allocations);
88
89 reset_statistics();
90 }
91
92 void ThreadLocalAllocBuffer::insert_filler() {
93 assert(end() != NULL, "Must not be retired");
94 Fill::range(top(), hard_end());
95 }
96
97 void ThreadLocalAllocBuffer::make_parsable() {
98 if (end() != NULL) {
99 invariants();
100 if (ZeroTLAB) {
101 retire();
102 } else {
103 insert_filler();
104 }
105 }
106 }
107
108 void ThreadLocalAllocBuffer::retire(ThreadLocalAllocStats* stats) {
109 if (stats != NULL) {
110 accumulate_and_reset_statistics(stats);
111 }
112
113 if (end() != NULL) {
114 invariants();
115 thread()->incr_allocated_bytes(used_bytes());
116 insert_filler();
117 initialize(NULL, NULL, NULL);
118 }
119 }
120
121 void ThreadLocalAllocBuffer::retire_before_allocation() {
122 _slow_refill_waste += (unsigned int)remaining();
123 retire();
124 }
125
126 void ThreadLocalAllocBuffer::resize() {
127 // Compute the next tlab size using expected allocation amount
128 assert(ResizeTLAB, "Should not call this otherwise");
129 size_t alloc = (size_t)(_allocation_fraction.average() *
130 (Universe::heap()->tlab_capacity(thread()) / HeapWordSize));
131 size_t new_size = alloc / _target_refills;
132
133 new_size = MIN2(MAX2(new_size, min_size()), max_size());
134
135 size_t aligned_new_size = align_object_size(new_size);
136
137 log_trace(gc, tlab)("TLAB new size: thread: " INTPTR_FORMAT " [id: %2d]"
138 " refills %d alloc: %8.6f desired_size: " SIZE_FORMAT " -> " SIZE_FORMAT,
139 p2i(thread()), thread()->osthread()->thread_id(),
140 _target_refills, _allocation_fraction.average(), desired_size(), aligned_new_size);
141
142 set_desired_size(aligned_new_size);
143 set_refill_waste_limit(initial_refill_waste_limit());
144 }
145
146 void ThreadLocalAllocBuffer::reset_statistics() {
147 _number_of_refills = 0;
148 _fast_refill_waste = 0;
149 _slow_refill_waste = 0;
150 _gc_waste = 0;
151 _slow_allocations = 0;
152 _allocated_size = 0;
153 }
154
155 void ThreadLocalAllocBuffer::fill(HeapWord* start,
156 HeapWord* top,
157 size_t new_size) {
158 _number_of_refills++;
159 _allocated_size += new_size;
160 print_stats("fill");
161 assert(top <= start + new_size - alignment_reserve(), "size too small");
162
163 initialize(start, top, start + new_size - alignment_reserve());
164
165 // Reset amount of internal fragmentation
166 set_refill_waste_limit(initial_refill_waste_limit());
167 }
168
169 void ThreadLocalAllocBuffer::initialize(HeapWord* start,
170 HeapWord* top,
171 HeapWord* end) {
172 set_start(start);
173 set_top(top);
174 set_pf_top(top);
175 set_end(end);
176 set_allocation_end(end);
177 invariants();
178 }
179
180 void ThreadLocalAllocBuffer::initialize() {
181 initialize(NULL, // start
182 NULL, // top
183 NULL); // end
184
185 set_desired_size(initial_desired_size());
186
187 size_t capacity = Universe::heap()->tlab_capacity(thread()) / HeapWordSize;
188 double alloc_frac = desired_size() * target_refills() / (double) capacity;
189 _allocation_fraction.sample(alloc_frac);
190
191 set_refill_waste_limit(initial_refill_waste_limit());
192
193 reset_statistics();
194 }
195
196 void ThreadLocalAllocBuffer::startup_initialization() {
197 ThreadLocalAllocStats::initialize();
198
199 // Assuming each thread's active tlab is, on average,
200 // 1/2 full at a GC
201 _target_refills = 100 / (2 * TLABWasteTargetPercent);
202 // We need to set initial target refills to 2 to avoid a GC which causes VM
203 // abort during VM initialization.
204 _target_refills = MAX2(_target_refills, 2U);
205
206 #ifdef COMPILER2
207 // If the C2 compiler is present, extra space is needed at the end of
208 // TLABs, otherwise prefetching instructions generated by the C2
209 // compiler will fault (due to accessing memory outside of heap).
210 // The amount of space is the max of the number of lines to
211 // prefetch for array and for instance allocations. (Extra space must be
212 // reserved to accommodate both types of allocations.)
213 //
214 // Only SPARC-specific BIS instructions are known to fault. (Those
215 // instructions are generated if AllocatePrefetchStyle==3 and
216 // AllocatePrefetchInstr==1). To be on the safe side, however,
217 // extra space is reserved for all combinations of
218 // AllocatePrefetchStyle and AllocatePrefetchInstr.
219 //
220 // If the C2 compiler is not present, no space is reserved.
221
222 // +1 for rounding up to next cache line, +1 to be safe
223 if (is_server_compilation_mode_vm()) {
224 int lines = MAX2(AllocatePrefetchLines, AllocateInstancePrefetchLines) + 2;
225 _reserve_for_allocation_prefetch = (AllocatePrefetchDistance + AllocatePrefetchStepSize * lines) /
226 (int)HeapWordSize;
227 }
228 #endif
229
230 // During jvm startup, the main thread is initialized
231 // before the heap is initialized. So reinitialize it now.
232 guarantee(Thread::current()->is_Java_thread(), "tlab initialization thread not Java thread");
233 Thread::current()->tlab().initialize();
234
235 log_develop_trace(gc, tlab)("TLAB min: " SIZE_FORMAT " initial: " SIZE_FORMAT " max: " SIZE_FORMAT,
236 min_size(), Thread::current()->tlab().initial_desired_size(), max_size());
237 }
238
239 size_t ThreadLocalAllocBuffer::initial_desired_size() {
240 size_t init_sz = 0;
241
242 if (TLABSize > 0) {
243 init_sz = TLABSize / HeapWordSize;
244 } else {
245 // Initial size is a function of the average number of allocating threads.
246 unsigned int nof_threads = ThreadLocalAllocStats::allocating_threads_avg();
247
248 init_sz = (Universe::heap()->tlab_capacity(thread()) / HeapWordSize) /
249 (nof_threads * target_refills());
250 init_sz = align_object_size(init_sz);
251 }
252 init_sz = MIN2(MAX2(init_sz, min_size()), max_size());
253 return init_sz;
254 }
255
256 void ThreadLocalAllocBuffer::print_stats(const char* tag) {
257 Log(gc, tlab) log;
258 if (!log.is_trace()) {
259 return;
260 }
261
262 Thread* thrd = thread();
263 size_t waste = _gc_waste + _slow_refill_waste + _fast_refill_waste;
264 double waste_percent = percent_of(waste, _allocated_size);
265 size_t tlab_used = Universe::heap()->tlab_used(thrd);
266 log.trace("TLAB: %s thread: " INTPTR_FORMAT " [id: %2d]"
267 " desired_size: " SIZE_FORMAT "KB"
268 " slow allocs: %d refill waste: " SIZE_FORMAT "B"
269 " alloc:%8.5f %8.0fKB refills: %d waste %4.1f%% gc: %dB"
270 " slow: %dB fast: %dB",
271 tag, p2i(thrd), thrd->osthread()->thread_id(),
272 _desired_size / (K / HeapWordSize),
273 _slow_allocations, _refill_waste_limit * HeapWordSize,
274 _allocation_fraction.average(),
275 _allocation_fraction.average() * tlab_used / K,
276 _number_of_refills, waste_percent,
277 _gc_waste * HeapWordSize,
278 _slow_refill_waste * HeapWordSize,
279 _fast_refill_waste * HeapWordSize);
280 }
281
282 void ThreadLocalAllocBuffer::verify() {
283 HeapWord* p = start();
284 HeapWord* t = top();
285 HeapWord* prev_p = NULL;
286 while (p < t) {
287 oopDesc::verify(oop(p));
288 prev_p = p;
289 p += oop(p)->size();
290 }
291 guarantee(p == top(), "end of last object must match end of space");
292 }
293
294 void ThreadLocalAllocBuffer::set_sample_end() {
295 size_t heap_words_remaining = pointer_delta(_end, _top);
296 size_t bytes_until_sample = thread()->heap_sampler().bytes_until_sample();
297 size_t words_until_sample = bytes_until_sample / HeapWordSize;
298
299 if (heap_words_remaining > words_until_sample) {
300 HeapWord* new_end = _top + words_until_sample;
301 set_end(new_end);
302 _bytes_since_last_sample_point = bytes_until_sample;
303 } else {
304 _bytes_since_last_sample_point = heap_words_remaining * HeapWordSize;
305 }
306 }
307
308 Thread* ThreadLocalAllocBuffer::thread() {
309 return (Thread*)(((char*)this) + in_bytes(start_offset()) - in_bytes(Thread::tlab_start_offset()));
310 }
311
312 void ThreadLocalAllocBuffer::set_back_allocation_end() {
313 _end = _allocation_end;
314 }
315
316 HeapWord* ThreadLocalAllocBuffer::hard_end() {
317 return _allocation_end + alignment_reserve();
318 }
319
320 PerfVariable* ThreadLocalAllocStats::_perf_allocating_threads;
321 PerfVariable* ThreadLocalAllocStats::_perf_total_refills;
322 PerfVariable* ThreadLocalAllocStats::_perf_max_refills;
323 PerfVariable* ThreadLocalAllocStats::_perf_total_allocations;
324 PerfVariable* ThreadLocalAllocStats::_perf_total_gc_waste;
325 PerfVariable* ThreadLocalAllocStats::_perf_max_gc_waste;
326 PerfVariable* ThreadLocalAllocStats::_perf_total_slow_refill_waste;
327 PerfVariable* ThreadLocalAllocStats::_perf_max_slow_refill_waste;
328 PerfVariable* ThreadLocalAllocStats::_perf_total_fast_refill_waste;
329 PerfVariable* ThreadLocalAllocStats::_perf_max_fast_refill_waste;
330 PerfVariable* ThreadLocalAllocStats::_perf_total_slow_allocations;
331 PerfVariable* ThreadLocalAllocStats::_perf_max_slow_allocations;
332 AdaptiveWeightedAverage ThreadLocalAllocStats::_allocating_threads_avg(0);
333
334 static PerfVariable* create_perf_variable(const char* name, PerfData::Units unit, TRAPS) {
335 ResourceMark rm;
336 return PerfDataManager::create_variable(SUN_GC, PerfDataManager::counter_name("tlab", name), unit, THREAD);
337 }
338
339 void ThreadLocalAllocStats::initialize() {
340 _allocating_threads_avg = AdaptiveWeightedAverage(TLABAllocationWeight);
341 _allocating_threads_avg.sample(1); // One allocating thread at startup
342
343 if (UsePerfData) {
344 EXCEPTION_MARK;
345 _perf_allocating_threads = create_perf_variable("allocThreads", PerfData::U_None, CHECK);
346 _perf_total_refills = create_perf_variable("fills", PerfData::U_None, CHECK);
347 _perf_max_refills = create_perf_variable("maxFills", PerfData::U_None, CHECK);
348 _perf_total_allocations = create_perf_variable("alloc", PerfData::U_Bytes, CHECK);
349 _perf_total_gc_waste = create_perf_variable("gcWaste", PerfData::U_Bytes, CHECK);
350 _perf_max_gc_waste = create_perf_variable("maxGcWaste", PerfData::U_Bytes, CHECK);
351 _perf_total_slow_refill_waste = create_perf_variable("slowWaste", PerfData::U_Bytes, CHECK);
352 _perf_max_slow_refill_waste = create_perf_variable("maxSlowWaste", PerfData::U_Bytes, CHECK);
353 _perf_total_fast_refill_waste = create_perf_variable("fastWaste", PerfData::U_Bytes, CHECK);
354 _perf_max_fast_refill_waste = create_perf_variable("maxFastWaste", PerfData::U_Bytes, CHECK);
355 _perf_total_slow_allocations = create_perf_variable("slowAlloc", PerfData::U_None, CHECK);
356 _perf_max_slow_allocations = create_perf_variable("maxSlowAlloc", PerfData::U_None, CHECK);
357 }
358 }
359
360 ThreadLocalAllocStats::ThreadLocalAllocStats() :
361 _allocating_threads(0),
362 _total_refills(0),
363 _max_refills(0),
364 _total_allocations(0),
365 _total_gc_waste(0),
366 _max_gc_waste(0),
367 _total_fast_refill_waste(0),
368 _max_fast_refill_waste(0),
369 _total_slow_refill_waste(0),
370 _max_slow_refill_waste(0),
371 _total_slow_allocations(0),
372 _max_slow_allocations(0) {}
373
374 unsigned int ThreadLocalAllocStats::allocating_threads_avg() {
375 return MAX2((unsigned int)(_allocating_threads_avg.average() + 0.5), 1U);
376 }
377
378 void ThreadLocalAllocStats::update_fast_allocations(unsigned int refills,
379 size_t allocations,
380 size_t gc_waste,
381 size_t fast_refill_waste,
382 size_t slow_refill_waste) {
383 _allocating_threads += 1;
384 _total_refills += refills;
385 _max_refills = MAX2(_max_refills, refills);
386 _total_allocations += allocations;
387 _total_gc_waste += gc_waste;
388 _max_gc_waste = MAX2(_max_gc_waste, gc_waste);
389 _total_fast_refill_waste += fast_refill_waste;
390 _max_fast_refill_waste = MAX2(_max_fast_refill_waste, fast_refill_waste);
391 _total_slow_refill_waste += slow_refill_waste;
392 _max_slow_refill_waste = MAX2(_max_slow_refill_waste, slow_refill_waste);
393 }
394
395 void ThreadLocalAllocStats::update_slow_allocations(unsigned int allocations) {
396 _total_slow_allocations += allocations;
397 _max_slow_allocations = MAX2(_max_slow_allocations, allocations);
398 }
399
400 void ThreadLocalAllocStats::update(const ThreadLocalAllocStats& other) {
401 _allocating_threads += other._allocating_threads;
402 _total_refills += other._total_refills;
403 _max_refills = MAX2(_max_refills, other._max_refills);
404 _total_allocations += other._total_allocations;
405 _total_gc_waste += other._total_gc_waste;
406 _max_gc_waste = MAX2(_max_gc_waste, other._max_gc_waste);
407 _total_fast_refill_waste += other._total_fast_refill_waste;
408 _max_fast_refill_waste = MAX2(_max_fast_refill_waste, other._max_fast_refill_waste);
409 _total_slow_refill_waste += other._total_slow_refill_waste;
410 _max_slow_refill_waste = MAX2(_max_slow_refill_waste, other._max_slow_refill_waste);
411 _total_slow_allocations += other._total_slow_allocations;
412 _max_slow_allocations = MAX2(_max_slow_allocations, other._max_slow_allocations);
413 }
414
415 void ThreadLocalAllocStats::reset() {
416 _allocating_threads = 0;
417 _total_refills = 0;
418 _max_refills = 0;
419 _total_allocations = 0;
420 _total_gc_waste = 0;
421 _max_gc_waste = 0;
422 _total_fast_refill_waste = 0;
423 _max_fast_refill_waste = 0;
424 _total_slow_refill_waste = 0;
425 _max_slow_refill_waste = 0;
426 _total_slow_allocations = 0;
427 _max_slow_allocations = 0;
428 }
429
430 void ThreadLocalAllocStats::publish() {
431 if (_total_allocations == 0) {
432 return;
433 }
434
435 _allocating_threads_avg.sample(_allocating_threads);
436
437 const size_t waste = _total_gc_waste + _total_slow_refill_waste + _total_fast_refill_waste;
438 const double waste_percent = percent_of(waste, _total_allocations);
439 log_debug(gc, tlab)("TLAB totals: thrds: %d refills: %d max: %d"
440 " slow allocs: %d max %d waste: %4.1f%%"
441 " gc: " SIZE_FORMAT "B max: " SIZE_FORMAT "B"
442 " slow: " SIZE_FORMAT "B max: " SIZE_FORMAT "B"
443 " fast: " SIZE_FORMAT "B max: " SIZE_FORMAT "B",
444 _allocating_threads, _total_refills, _max_refills,
445 _total_slow_allocations, _max_slow_allocations, waste_percent,
446 _total_gc_waste * HeapWordSize, _max_gc_waste * HeapWordSize,
447 _total_slow_refill_waste * HeapWordSize, _max_slow_refill_waste * HeapWordSize,
448 _total_fast_refill_waste * HeapWordSize, _max_fast_refill_waste * HeapWordSize);
449
450 if (UsePerfData) {
451 _perf_allocating_threads ->set_value(_allocating_threads);
452 _perf_total_refills ->set_value(_total_refills);
453 _perf_max_refills ->set_value(_max_refills);
454 _perf_total_allocations ->set_value(_total_allocations);
455 _perf_total_gc_waste ->set_value(_total_gc_waste);
456 _perf_max_gc_waste ->set_value(_max_gc_waste);
457 _perf_total_slow_refill_waste ->set_value(_total_slow_refill_waste);
458 _perf_max_slow_refill_waste ->set_value(_max_slow_refill_waste);
459 _perf_total_fast_refill_waste ->set_value(_total_fast_refill_waste);
460 _perf_max_fast_refill_waste ->set_value(_max_fast_refill_waste);
461 _perf_total_slow_allocations ->set_value(_total_slow_allocations);
462 _perf_max_slow_allocations ->set_value(_max_slow_allocations);
463 }
464 }