1 /*
2 * Copyright (c) 1999, 2020, 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 "memory/genCollectedHeap.hpp"
27 #include "memory/resourceArea.hpp"
28 #include "memory/threadLocalAllocBuffer.inline.hpp"
29 #include "memory/universe.inline.hpp"
30 #include "oops/oop.inline.hpp"
31 #include "runtime/thread.inline.hpp"
32 #include "utilities/copy.hpp"
33
34 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
35
36 // Thread-Local Edens support
37
38 // static member initialization
39 size_t ThreadLocalAllocBuffer::_max_size = 0;
40 unsigned ThreadLocalAllocBuffer::_target_refills = 0;
41 GlobalTLABStats* ThreadLocalAllocBuffer::_global_stats = NULL;
42
43 void ThreadLocalAllocBuffer::clear_before_allocation() {
44 _slow_refill_waste += (unsigned)remaining();
45 make_parsable(true); // also retire the TLAB
46 }
47
48 void ThreadLocalAllocBuffer::accumulate_statistics_before_gc() {
49 global_stats()->initialize();
50
51 for (JavaThread *thread = Threads::first(); thread != NULL; thread = thread->next()) {
52 thread->tlab().accumulate_statistics();
53 thread->tlab().initialize_statistics();
54 }
55
56 Universe::heap()->accumulate_statistics_all_gclabs();
57
58 // Publish new stats if some allocation occurred.
59 if (global_stats()->allocation() != 0) {
60 global_stats()->publish();
61 if (PrintTLAB) {
62 global_stats()->print();
63 }
64 }
65 }
66
67 void ThreadLocalAllocBuffer::accumulate_statistics() {
68 Thread* thread = myThread();
69 size_t capacity = Universe::heap()->tlab_capacity(thread);
70 size_t used = Universe::heap()->tlab_used(thread);
71
72 _gc_waste += (unsigned)remaining();
73 size_t total_allocated = _gclab ? thread->allocated_bytes_gclab() : thread->allocated_bytes();
74 size_t allocated_since_last_gc = total_allocated - _allocated_before_last_gc;
75 _allocated_before_last_gc = total_allocated;
76
77 if (PrintTLAB && (_number_of_refills > 0 || Verbose)) {
78 print_stats("gc");
79 }
80
81 if (_number_of_refills > 0) {
82 // Update allocation history if a reasonable amount of eden was allocated.
83 bool update_allocation_history = used > 0.5 * capacity;
84
85 if (update_allocation_history) {
86 // Average the fraction of eden allocated in a tlab by this
87 // thread for use in the next resize operation.
88 // _gc_waste is not subtracted because it's included in
89 // "used".
90 // The result can be larger than 1.0 due to direct to old allocations.
91 // These allocations should ideally not be counted but since it is not possible
92 // to filter them out here we just cap the fraction to be at most 1.0.
93 // Keep alloc_frac as float and not double to avoid the double to float conversion
94 float alloc_frac = MIN2(1.0f, allocated_since_last_gc / (float) used);
95 _allocation_fraction.sample(alloc_frac);
96 }
97 global_stats()->update_allocating_threads();
98 global_stats()->update_number_of_refills(_number_of_refills);
99 global_stats()->update_allocation(_number_of_refills * desired_size());
100 global_stats()->update_gc_waste(_gc_waste);
101 global_stats()->update_slow_refill_waste(_slow_refill_waste);
102 global_stats()->update_fast_refill_waste(_fast_refill_waste);
103
104 } else {
105 assert(_number_of_refills == 0 && _fast_refill_waste == 0 &&
106 _slow_refill_waste == 0 && _gc_waste == 0,
107 "tlab stats == 0");
108 }
109 global_stats()->update_slow_allocations(_slow_allocations);
110 }
111
112 // Fills the current tlab with a dummy filler array to create
113 // an illusion of a contiguous Eden and optionally retires the tlab.
114 // Waste accounting should be done in caller as appropriate; see,
115 // for example, clear_before_allocation().
116 void ThreadLocalAllocBuffer::make_parsable(bool retire) {
117 if (end() != NULL) {
118 invariants();
119
120 if (retire) {
121 if (_gclab) {
122 myThread()->incr_allocated_bytes_gclab(used_bytes());
123 } else {
124 myThread()->incr_allocated_bytes(used_bytes());
125 }
126 }
127
128 CollectedHeap::fill_with_object(top(), hard_end(), retire);
129
130 if (retire || ZeroTLAB) { // "Reset" the TLAB
131 set_start(NULL);
132 set_top(NULL);
133 set_pf_top(NULL);
134 set_end(NULL);
135 }
136 }
137 assert(!(retire || ZeroTLAB) ||
138 (start() == NULL && end() == NULL && top() == NULL),
139 "TLAB must be reset");
140 }
141
142 void ThreadLocalAllocBuffer::resize_all_tlabs() {
143 if (ResizeTLAB) {
144 for (JavaThread *thread = Threads::first(); thread != NULL; thread = thread->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 if (PrintTLAB && Verbose) {
162 gclog_or_tty->print("TLAB new size: thread: " INTPTR_FORMAT " [id: %2d]"
163 " refills %d alloc: %8.6f desired_size: " SIZE_FORMAT " -> " SIZE_FORMAT "\n",
164 myThread(), myThread()->osthread()->thread_id(),
165 _target_refills, _allocation_fraction.average(), desired_size(), aligned_new_size);
166 }
167 set_desired_size(aligned_new_size);
168 set_refill_waste_limit(initial_refill_waste_limit());
169 }
170
171 void ThreadLocalAllocBuffer::initialize_statistics() {
172 _number_of_refills = 0;
173 _fast_refill_waste = 0;
174 _slow_refill_waste = 0;
175 _gc_waste = 0;
176 _slow_allocations = 0;
177 }
178
179 void ThreadLocalAllocBuffer::fill(HeapWord* start,
180 HeapWord* top,
181 size_t new_size) {
182 _number_of_refills++;
183 if (PrintTLAB && Verbose) {
184 print_stats("fill");
185 }
186 assert(top <= start + new_size - alignment_reserve(), "size too small");
187 initialize(start, top, start + new_size - alignment_reserve());
188
189 // Reset amount of internal fragmentation
190 set_refill_waste_limit(initial_refill_waste_limit());
191 }
192
193 void ThreadLocalAllocBuffer::initialize(HeapWord* start,
194 HeapWord* top,
195 HeapWord* end) {
196 set_start(start);
197 set_top(top);
198 set_pf_top(top);
199 set_end(end);
200 invariants();
201 }
202
203 void ThreadLocalAllocBuffer::initialize(bool gclab) {
204 _initialized = true;
205 _gclab = gclab;
206 initialize(NULL, // start
207 NULL, // top
208 NULL); // end
209
210 set_desired_size(initial_desired_size());
211
212 // Following check is needed because at startup the main
213 // thread is initialized before the heap is. The initialization for
214 // this thread is redone in startup_initialization below.
215 if (Universe::heap() != NULL) {
216 size_t capacity = Universe::heap()->tlab_capacity(myThread()) / HeapWordSize;
217 // Keep alloc_frac as float and not double to avoid the double to float conversion
218 float alloc_frac = desired_size() * target_refills() / (float) 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 // During jvm startup, the main thread is initialized
237 // before the heap is initialized. So reinitialize it now.
238 guarantee(Thread::current()->is_Java_thread(), "tlab initialization thread not Java thread");
239 Thread::current()->tlab().initialize(false);
240 if (UseShenandoahGC) {
241 Thread::current()->gclab().initialize(true);
242 }
243
244 if (PrintTLAB && Verbose) {
245 gclog_or_tty->print("TLAB min: " SIZE_FORMAT " initial: " SIZE_FORMAT " max: " SIZE_FORMAT "\n",
246 min_size(), Thread::current()->tlab().initial_desired_size(), max_size());
247 }
248 }
249
250 size_t ThreadLocalAllocBuffer::initial_desired_size() {
251 size_t init_sz = 0;
252
253 if (TLABSize > 0) {
254 init_sz = TLABSize / HeapWordSize;
255 } else if (global_stats() != NULL) {
256 // Initial size is a function of the average number of allocating threads.
257 unsigned nof_threads = global_stats()->allocating_threads_avg();
258
259 init_sz = (Universe::heap()->tlab_capacity(myThread()) / HeapWordSize) /
260 (nof_threads * target_refills());
261 init_sz = align_object_size(init_sz);
262 }
263 init_sz = MIN2(MAX2(init_sz, min_size()), max_size());
264 return init_sz;
265 }
266
267 void ThreadLocalAllocBuffer::print_stats(const char* tag) {
268 Thread* thrd = myThread();
269 size_t waste = _gc_waste + _slow_refill_waste + _fast_refill_waste;
270 size_t alloc = _number_of_refills * _desired_size;
271 double waste_percent = alloc == 0 ? 0.0 :
272 100.0 * waste / alloc;
273 size_t tlab_used = Universe::heap()->tlab_used(thrd);
274 gclog_or_tty->print("TLAB: %s %s thread: " INTPTR_FORMAT " [id: %2d]"
275 " desired_size: " SIZE_FORMAT "KB"
276 " slow allocs: %d refill waste: " SIZE_FORMAT "B"
277 " alloc:%8.5f %8.0fKB refills: %d waste %4.1f%% gc: %dB"
278 " slow: %dB fast: %dB\n",
279 tag, _gclab ? "gclab" : "tlab ", p2i(thrd), thrd->osthread()->thread_id(),
280 _desired_size / (K / HeapWordSize),
281 _slow_allocations, _refill_waste_limit * HeapWordSize,
282 _allocation_fraction.average(),
283 _allocation_fraction.average() * tlab_used / K,
284 _number_of_refills, waste_percent,
285 _gc_waste * HeapWordSize,
286 _slow_refill_waste * HeapWordSize,
287 _fast_refill_waste * HeapWordSize);
288 }
289
290 void ThreadLocalAllocBuffer::verify() {
291 HeapWord* p = start();
292 HeapWord* t = top();
293 HeapWord* prev_p = NULL;
294 while (p < t) {
295 oop(p)->verify();
296 prev_p = p;
297 p += oop(p)->size();
298 }
299 guarantee(p == top(), "end of last object must match end of space");
300 }
301
302 Thread* ThreadLocalAllocBuffer::myThread() {
303 ByteSize gclab_offset = Thread::gclab_start_offset();
304 ByteSize tlab_offset = Thread::tlab_start_offset();
305 ByteSize offs = _gclab ? gclab_offset : tlab_offset;
306 Thread* thread = (Thread*)(((char *)this) +
307 in_bytes(start_offset()) - in_bytes(offs));
308 #ifdef ASSERT
309 assert(this == (_gclab ? &thread->gclab() : &thread->tlab()), "must be");
310 #endif
311 return thread;
312 }
313
314 void ThreadLocalAllocBuffer::rollback(size_t size) {
315 HeapWord* old_top = top();
316 if (old_top != NULL) { // Pathological case: we accept that we can't rollback.
317 set_top(old_top - size);
318 }
319 }
320
321
322 GlobalTLABStats::GlobalTLABStats() :
323 _allocating_threads_avg(TLABAllocationWeight) {
324
325 initialize();
326
327 _allocating_threads_avg.sample(1); // One allocating thread at startup
328
329 if (UsePerfData) {
330
331 EXCEPTION_MARK;
332 ResourceMark rm;
333
334 char* cname = PerfDataManager::counter_name("tlab", "allocThreads");
335 _perf_allocating_threads =
336 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
337
338 cname = PerfDataManager::counter_name("tlab", "fills");
339 _perf_total_refills =
340 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
341
342 cname = PerfDataManager::counter_name("tlab", "maxFills");
343 _perf_max_refills =
344 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
345
346 cname = PerfDataManager::counter_name("tlab", "alloc");
347 _perf_allocation =
348 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
349
350 cname = PerfDataManager::counter_name("tlab", "gcWaste");
351 _perf_gc_waste =
352 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
353
354 cname = PerfDataManager::counter_name("tlab", "maxGcWaste");
355 _perf_max_gc_waste =
356 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
357
358 cname = PerfDataManager::counter_name("tlab", "slowWaste");
359 _perf_slow_refill_waste =
360 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
361
362 cname = PerfDataManager::counter_name("tlab", "maxSlowWaste");
363 _perf_max_slow_refill_waste =
364 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
365
366 cname = PerfDataManager::counter_name("tlab", "fastWaste");
367 _perf_fast_refill_waste =
368 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
369
370 cname = PerfDataManager::counter_name("tlab", "maxFastWaste");
371 _perf_max_fast_refill_waste =
372 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
373
374 cname = PerfDataManager::counter_name("tlab", "slowAlloc");
375 _perf_slow_allocations =
376 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
377
378 cname = PerfDataManager::counter_name("tlab", "maxSlowAlloc");
379 _perf_max_slow_allocations =
380 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
381 }
382 }
383
384 void GlobalTLABStats::initialize() {
385 // Clear counters summarizing info from all threads
386 _allocating_threads = 0;
387 _total_refills = 0;
388 _max_refills = 0;
389 _total_allocation = 0;
390 _total_gc_waste = 0;
391 _max_gc_waste = 0;
392 _total_slow_refill_waste = 0;
393 _max_slow_refill_waste = 0;
394 _total_fast_refill_waste = 0;
395 _max_fast_refill_waste = 0;
396 _total_slow_allocations = 0;
397 _max_slow_allocations = 0;
398 }
399
400 void GlobalTLABStats::publish() {
401 _allocating_threads_avg.sample(_allocating_threads);
402 if (UsePerfData) {
403 _perf_allocating_threads ->set_value(_allocating_threads);
404 _perf_total_refills ->set_value(_total_refills);
405 _perf_max_refills ->set_value(_max_refills);
406 _perf_allocation ->set_value(_total_allocation);
407 _perf_gc_waste ->set_value(_total_gc_waste);
408 _perf_max_gc_waste ->set_value(_max_gc_waste);
409 _perf_slow_refill_waste ->set_value(_total_slow_refill_waste);
410 _perf_max_slow_refill_waste->set_value(_max_slow_refill_waste);
411 _perf_fast_refill_waste ->set_value(_total_fast_refill_waste);
412 _perf_max_fast_refill_waste->set_value(_max_fast_refill_waste);
413 _perf_slow_allocations ->set_value(_total_slow_allocations);
414 _perf_max_slow_allocations ->set_value(_max_slow_allocations);
415 }
416 }
417
418 void GlobalTLABStats::print() {
419 size_t waste = _total_gc_waste + _total_slow_refill_waste + _total_fast_refill_waste;
420 double waste_percent = _total_allocation == 0 ? 0.0 :
421 100.0 * waste / _total_allocation;
422 gclog_or_tty->print("TLAB totals: thrds: %d refills: %d max: %d"
423 " slow allocs: %d max %d waste: %4.1f%%"
424 " gc: " SIZE_FORMAT "B max: " SIZE_FORMAT "B"
425 " slow: " SIZE_FORMAT "B max: " SIZE_FORMAT "B"
426 " fast: " SIZE_FORMAT "B max: " SIZE_FORMAT "B\n",
427 _allocating_threads,
428 _total_refills, _max_refills,
429 _total_slow_allocations, _max_slow_allocations,
430 waste_percent,
431 _total_gc_waste * HeapWordSize,
432 _max_gc_waste * HeapWordSize,
433 _total_slow_refill_waste * HeapWordSize,
434 _max_slow_refill_waste * HeapWordSize,
435 _total_fast_refill_waste * HeapWordSize,
436 _max_fast_refill_waste * HeapWordSize);
437 }