1 /*
2 * Copyright (c) 1999, 2015, 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 "memory/resourceArea.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 // Thread-Local Edens support
35
36 // static member initialization
37 size_t ThreadLocalAllocBuffer::_max_size = 0;
38 unsigned ThreadLocalAllocBuffer::_target_refills = 0;
39 GlobalTLABStats* ThreadLocalAllocBuffer::_global_stats = NULL;
40
41 void ThreadLocalAllocBuffer::clear_before_allocation() {
42 _slow_refill_waste += (unsigned)remaining();
43 make_parsable(true); // also retire the TLAB
44 }
45
46 void ThreadLocalAllocBuffer::accumulate_statistics_before_gc() {
47 global_stats()->initialize();
48
49 for (JavaThread *thread = Threads::first(); thread != NULL; thread = thread->next()) {
50 thread->tlab().accumulate_statistics();
51 thread->tlab().initialize_statistics();
52 }
53
54 // Publish new stats if some allocation occurred.
55 if (global_stats()->allocation() != 0) {
56 global_stats()->publish();
57 if (PrintTLAB) {
58 global_stats()->print();
59 }
60 }
61 }
62
63 void ThreadLocalAllocBuffer::accumulate_statistics() {
64 Thread* thread = myThread();
65 size_t capacity = Universe::heap()->tlab_capacity(thread);
66 size_t used = Universe::heap()->tlab_used(thread);
67
68 _gc_waste += (unsigned)remaining();
69 size_t total_allocated = thread->allocated_bytes();
70 size_t allocated_since_last_gc = total_allocated - _allocated_before_last_gc;
71 _allocated_before_last_gc = total_allocated;
72
73 if (PrintTLAB && (_number_of_refills > 0 || Verbose)) {
74 print_stats("gc");
75 }
76
77 if (_number_of_refills > 0) {
78 // Update allocation history if a reasonable amount of eden was allocated.
79 bool update_allocation_history = used > 0.5 * capacity;
80
81 if (update_allocation_history) {
82 // Average the fraction of eden allocated in a tlab by this
83 // thread for use in the next resize operation.
84 // _gc_waste is not subtracted because it's included in
85 // "used".
86 // The result can be larger than 1.0 due to direct to old allocations.
87 // These allocations should ideally not be counted but since it is not possible
88 // to filter them out here we just cap the fraction to be at most 1.0.
89 double alloc_frac = MIN2(1.0, (double) allocated_since_last_gc / used);
90 _allocation_fraction.sample(alloc_frac);
91 }
92 global_stats()->update_allocating_threads();
93 global_stats()->update_number_of_refills(_number_of_refills);
94 global_stats()->update_allocation(_number_of_refills * desired_size());
95 global_stats()->update_gc_waste(_gc_waste);
96 global_stats()->update_slow_refill_waste(_slow_refill_waste);
97 global_stats()->update_fast_refill_waste(_fast_refill_waste);
98
99 } else {
100 assert(_number_of_refills == 0 && _fast_refill_waste == 0 &&
101 _slow_refill_waste == 0 && _gc_waste == 0,
102 "tlab stats == 0");
103 }
104 global_stats()->update_slow_allocations(_slow_allocations);
105 }
106
107 // Fills the current tlab with a dummy filler array to create
108 // an illusion of a contiguous Eden and optionally retires the tlab.
109 // Waste accounting should be done in caller as appropriate; see,
110 // for example, clear_before_allocation().
111 void ThreadLocalAllocBuffer::make_parsable(bool retire) {
112 if (end() != NULL) {
113 invariants();
114
115 if (retire) {
116 myThread()->incr_allocated_bytes(used_bytes());
117 }
118
119 CollectedHeap::fill_with_object(top(), hard_end(), retire);
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 (JavaThread *thread = Threads::first(); thread != NULL; thread = thread->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 if (PrintTLAB && Verbose) {
153 gclog_or_tty->print("TLAB new size: thread: " INTPTR_FORMAT " [id: %2d]"
154 " refills %d alloc: %8.6f desired_size: " SIZE_FORMAT " -> " SIZE_FORMAT "\n",
155 p2i(myThread()), myThread()->osthread()->thread_id(),
156 _target_refills, _allocation_fraction.average(), desired_size(), aligned_new_size);
157 }
158 set_desired_size(aligned_new_size);
159 set_refill_waste_limit(initial_refill_waste_limit());
160 }
161
162 void ThreadLocalAllocBuffer::initialize_statistics() {
163 _number_of_refills = 0;
164 _fast_refill_waste = 0;
165 _slow_refill_waste = 0;
166 _gc_waste = 0;
167 _slow_allocations = 0;
168 }
169
170 void ThreadLocalAllocBuffer::fill(HeapWord* start,
171 HeapWord* top,
172 size_t new_size) {
173 _number_of_refills++;
174 if (PrintTLAB && Verbose) {
175 print_stats("fill");
176 }
177 assert(top <= start + new_size - alignment_reserve(), "size too small");
178 initialize(start, top, start + new_size - alignment_reserve());
179
180 // Reset amount of internal fragmentation
181 set_refill_waste_limit(initial_refill_waste_limit());
182 }
183
184 void ThreadLocalAllocBuffer::initialize(HeapWord* start,
185 HeapWord* top,
186 HeapWord* end) {
187 set_start(start);
188 set_top(top);
189 set_pf_top(top);
190 set_end(end);
191 invariants();
192 }
193
194 void ThreadLocalAllocBuffer::initialize() {
195 initialize(NULL, // start
196 NULL, // top
197 NULL); // end
198
199 set_desired_size(initial_desired_size());
200
201 // Following check is needed because at startup the main (primordial)
202 // thread is initialized before the heap is. The initialization for
203 // this thread is redone in startup_initialization below.
204 if (Universe::heap() != NULL) {
205 size_t capacity = Universe::heap()->tlab_capacity(myThread()) / HeapWordSize;
206 double alloc_frac = desired_size() * target_refills() / (double) capacity;
207 _allocation_fraction.sample(alloc_frac);
208 }
209
210 set_refill_waste_limit(initial_refill_waste_limit());
211
212 initialize_statistics();
213 }
214
215 void ThreadLocalAllocBuffer::startup_initialization() {
216
217 // Assuming each thread's active tlab is, on average,
218 // 1/2 full at a GC
219 _target_refills = 100 / (2 * TLABWasteTargetPercent);
220 _target_refills = MAX2(_target_refills, (unsigned)1U);
221
222 _global_stats = new GlobalTLABStats();
223
224 // During jvm startup, the main (primordial) thread is initialized
225 // before the heap is initialized. So reinitialize it now.
226 guarantee(Thread::current()->is_Java_thread(), "tlab initialization thread not Java thread");
227 Thread::current()->tlab().initialize();
228
229 if (PrintTLAB && Verbose) {
230 gclog_or_tty->print("TLAB min: " SIZE_FORMAT " initial: " SIZE_FORMAT " max: " SIZE_FORMAT "\n",
231 min_size(), Thread::current()->tlab().initial_desired_size(), max_size());
232 }
233 }
234
235 size_t ThreadLocalAllocBuffer::initial_desired_size() {
236 size_t init_sz = 0;
237
238 if (TLABSize > 0) {
239 init_sz = TLABSize / HeapWordSize;
240 } else if (global_stats() != NULL) {
241 // Initial size is a function of the average number of allocating threads.
242 unsigned nof_threads = global_stats()->allocating_threads_avg();
243
244 init_sz = (Universe::heap()->tlab_capacity(myThread()) / HeapWordSize) /
245 (nof_threads * target_refills());
246 init_sz = align_object_size(init_sz);
247 }
248 init_sz = MIN2(MAX2(init_sz, min_size()), max_size());
249 return init_sz;
250 }
251
252 void ThreadLocalAllocBuffer::print_stats(const char* tag) {
253 Thread* thrd = myThread();
254 size_t waste = _gc_waste + _slow_refill_waste + _fast_refill_waste;
255 size_t alloc = _number_of_refills * _desired_size;
256 double waste_percent = alloc == 0 ? 0.0 :
257 100.0 * waste / alloc;
258 size_t tlab_used = Universe::heap()->tlab_used(thrd);
259 gclog_or_tty->print("TLAB: %s thread: " INTPTR_FORMAT " [id: %2d]"
260 " desired_size: " SIZE_FORMAT "KB"
261 " slow allocs: %d refill waste: " SIZE_FORMAT "B"
262 " alloc:%8.5f %8.0fKB refills: %d waste %4.1f%% gc: %dB"
263 " slow: %dB fast: %dB\n",
264 tag, p2i(thrd), thrd->osthread()->thread_id(),
265 _desired_size / (K / HeapWordSize),
266 _slow_allocations, _refill_waste_limit * HeapWordSize,
267 _allocation_fraction.average(),
268 _allocation_fraction.average() * tlab_used / K,
269 _number_of_refills, waste_percent,
270 _gc_waste * HeapWordSize,
271 _slow_refill_waste * HeapWordSize,
272 _fast_refill_waste * HeapWordSize);
273 }
274
275 void ThreadLocalAllocBuffer::verify() {
276 HeapWord* p = start();
277 HeapWord* t = top();
278 HeapWord* prev_p = NULL;
279 while (p < t) {
280 oop(p)->verify();
281 prev_p = p;
282 p += oop(p)->size();
283 }
284 guarantee(p == top(), "end of last object must match end of space");
285 }
286
287 Thread* ThreadLocalAllocBuffer::myThread() {
288 return (Thread*)(((char *)this) +
289 in_bytes(start_offset()) -
290 in_bytes(Thread::tlab_start_offset()));
291 }
292
293
294 GlobalTLABStats::GlobalTLABStats() :
295 _allocating_threads_avg(TLABAllocationWeight) {
296
297 initialize();
298
299 _allocating_threads_avg.sample(1); // One allocating thread at startup
300
301 if (UsePerfData) {
302
303 EXCEPTION_MARK;
304 ResourceMark rm;
305
306 char* cname = PerfDataManager::counter_name("tlab", "allocThreads");
307 _perf_allocating_threads =
308 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
309
310 cname = PerfDataManager::counter_name("tlab", "fills");
311 _perf_total_refills =
312 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
313
314 cname = PerfDataManager::counter_name("tlab", "maxFills");
315 _perf_max_refills =
316 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
317
318 cname = PerfDataManager::counter_name("tlab", "alloc");
319 _perf_allocation =
320 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
321
322 cname = PerfDataManager::counter_name("tlab", "gcWaste");
323 _perf_gc_waste =
324 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
325
326 cname = PerfDataManager::counter_name("tlab", "maxGcWaste");
327 _perf_max_gc_waste =
328 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
329
330 cname = PerfDataManager::counter_name("tlab", "slowWaste");
331 _perf_slow_refill_waste =
332 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
333
334 cname = PerfDataManager::counter_name("tlab", "maxSlowWaste");
335 _perf_max_slow_refill_waste =
336 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
337
338 cname = PerfDataManager::counter_name("tlab", "fastWaste");
339 _perf_fast_refill_waste =
340 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
341
342 cname = PerfDataManager::counter_name("tlab", "maxFastWaste");
343 _perf_max_fast_refill_waste =
344 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
345
346 cname = PerfDataManager::counter_name("tlab", "slowAlloc");
347 _perf_slow_allocations =
348 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
349
350 cname = PerfDataManager::counter_name("tlab", "maxSlowAlloc");
351 _perf_max_slow_allocations =
352 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
353 }
354 }
355
356 void GlobalTLABStats::initialize() {
357 // Clear counters summarizing info from all threads
358 _allocating_threads = 0;
359 _total_refills = 0;
360 _max_refills = 0;
361 _total_allocation = 0;
362 _total_gc_waste = 0;
363 _max_gc_waste = 0;
364 _total_slow_refill_waste = 0;
365 _max_slow_refill_waste = 0;
366 _total_fast_refill_waste = 0;
367 _max_fast_refill_waste = 0;
368 _total_slow_allocations = 0;
369 _max_slow_allocations = 0;
370 }
371
372 void GlobalTLABStats::publish() {
373 _allocating_threads_avg.sample(_allocating_threads);
374 if (UsePerfData) {
375 _perf_allocating_threads ->set_value(_allocating_threads);
376 _perf_total_refills ->set_value(_total_refills);
377 _perf_max_refills ->set_value(_max_refills);
378 _perf_allocation ->set_value(_total_allocation);
379 _perf_gc_waste ->set_value(_total_gc_waste);
380 _perf_max_gc_waste ->set_value(_max_gc_waste);
381 _perf_slow_refill_waste ->set_value(_total_slow_refill_waste);
382 _perf_max_slow_refill_waste->set_value(_max_slow_refill_waste);
383 _perf_fast_refill_waste ->set_value(_total_fast_refill_waste);
384 _perf_max_fast_refill_waste->set_value(_max_fast_refill_waste);
385 _perf_slow_allocations ->set_value(_total_slow_allocations);
386 _perf_max_slow_allocations ->set_value(_max_slow_allocations);
387 }
388 }
389
390 void GlobalTLABStats::print() {
391 size_t waste = _total_gc_waste + _total_slow_refill_waste + _total_fast_refill_waste;
392 double waste_percent = _total_allocation == 0 ? 0.0 :
393 100.0 * waste / _total_allocation;
394 gclog_or_tty->print("TLAB totals: thrds: %d refills: %d max: %d"
395 " slow allocs: %d max %d waste: %4.1f%%"
396 " gc: " SIZE_FORMAT "B max: " SIZE_FORMAT "B"
397 " slow: " SIZE_FORMAT "B max: " SIZE_FORMAT "B"
398 " fast: " SIZE_FORMAT "B max: " SIZE_FORMAT "B\n",
399 _allocating_threads,
400 _total_refills, _max_refills,
401 _total_slow_allocations, _max_slow_allocations,
402 waste_percent,
403 _total_gc_waste * HeapWordSize,
404 _max_gc_waste * HeapWordSize,
405 _total_slow_refill_waste * HeapWordSize,
406 _max_slow_refill_waste * HeapWordSize,
407 _total_fast_refill_waste * HeapWordSize,
408 _max_fast_refill_waste * HeapWordSize);
409 }