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 "logging/log.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "memory/universe.inline.hpp"
31 #include "oops/oop.inline.hpp"
32 #include "runtime/thread.inline.hpp"
33 #include "utilities/copy.hpp"
34
35 // Thread-Local Edens support
36
37 // static member initialization
38 size_t ThreadLocalAllocBuffer::_max_size = 0;
39 unsigned ThreadLocalAllocBuffer::_target_refills = 0;
40 GlobalTLABStats* ThreadLocalAllocBuffer::_global_stats = NULL;
41
42 void ThreadLocalAllocBuffer::clear_before_allocation() {
43 _slow_refill_waste += (unsigned)remaining();
44 make_parsable(true); // also retire the TLAB
45 }
46
47 void ThreadLocalAllocBuffer::accumulate_statistics_before_gc() {
48 global_stats()->initialize();
49
50 for (JavaThread *thread = Threads::first(); thread != NULL; thread = thread->next()) {
51 thread->tlab().accumulate_statistics();
52 thread->tlab().initialize_statistics();
53 }
54
55 // Publish new stats if some allocation occurred.
56 if (global_stats()->allocation() != 0) {
57 global_stats()->publish();
58 global_stats()->print();
59 }
60 }
61
62 void ThreadLocalAllocBuffer::accumulate_statistics() {
63 Thread* thread = myThread();
64 size_t capacity = Universe::heap()->tlab_capacity(thread);
65 size_t used = Universe::heap()->tlab_used(thread);
66
67 _gc_waste += (unsigned)remaining();
68 size_t total_allocated = thread->allocated_bytes();
69 size_t allocated_since_last_gc = total_allocated - _allocated_before_last_gc;
70 _allocated_before_last_gc = total_allocated;
71
72 print_stats("gc");
73
74 if (_number_of_refills > 0) {
75 // Update allocation history if a reasonable amount of eden was allocated.
76 bool update_allocation_history = used > 0.5 * capacity;
77
78 if (update_allocation_history) {
79 // Average the fraction of eden allocated in a tlab by this
80 // thread for use in the next resize operation.
81 // _gc_waste is not subtracted because it's included in
82 // "used".
83 // The result can be larger than 1.0 due to direct to old allocations.
84 // These allocations should ideally not be counted but since it is not possible
85 // to filter them out here we just cap the fraction to be at most 1.0.
86 double alloc_frac = MIN2(1.0, (double) allocated_since_last_gc / used);
87 _allocation_fraction.sample(alloc_frac);
88 }
89 global_stats()->update_allocating_threads();
90 global_stats()->update_number_of_refills(_number_of_refills);
91 global_stats()->update_allocation(_number_of_refills * desired_size());
92 global_stats()->update_gc_waste(_gc_waste);
93 global_stats()->update_slow_refill_waste(_slow_refill_waste);
94 global_stats()->update_fast_refill_waste(_fast_refill_waste);
95
96 } else {
97 assert(_number_of_refills == 0 && _fast_refill_waste == 0 &&
98 _slow_refill_waste == 0 && _gc_waste == 0,
99 "tlab stats == 0");
100 }
101 global_stats()->update_slow_allocations(_slow_allocations);
102 }
103
104 // Fills the current tlab with a dummy filler array to create
105 // an illusion of a contiguous Eden and optionally retires the tlab.
106 // Waste accounting should be done in caller as appropriate; see,
107 // for example, clear_before_allocation().
108 void ThreadLocalAllocBuffer::make_parsable(bool retire) {
109 if (end() != NULL) {
110 invariants();
111
112 if (retire) {
113 myThread()->incr_allocated_bytes(used_bytes());
114 }
115
116 CollectedHeap::fill_with_object(top(), hard_end(), retire);
117
118 if (retire || ZeroTLAB) { // "Reset" the TLAB
119 set_start(NULL);
120 set_top(NULL);
121 set_pf_top(NULL);
122 set_end(NULL);
123 }
124 }
125 assert(!(retire || ZeroTLAB) ||
126 (start() == NULL && end() == NULL && top() == NULL),
127 "TLAB must be reset");
128 }
129
130 void ThreadLocalAllocBuffer::resize_all_tlabs() {
131 if (ResizeTLAB) {
132 for (JavaThread *thread = Threads::first(); thread != NULL; thread = thread->next()) {
133 thread->tlab().resize();
134 }
135 }
136 }
137
138 void ThreadLocalAllocBuffer::resize() {
139 // Compute the next tlab size using expected allocation amount
140 assert(ResizeTLAB, "Should not call this otherwise");
141 size_t alloc = (size_t)(_allocation_fraction.average() *
142 (Universe::heap()->tlab_capacity(myThread()) / HeapWordSize));
143 size_t new_size = alloc / _target_refills;
144
145 new_size = MIN2(MAX2(new_size, min_size()), max_size());
146
147 size_t aligned_new_size = align_object_size(new_size);
148
149 log_trace(gc, tlab)("TLAB new size: thread: " INTPTR_FORMAT " [id: %2d]"
150 " refills %d alloc: %8.6f desired_size: " SIZE_FORMAT " -> " SIZE_FORMAT,
151 p2i(myThread()), myThread()->osthread()->thread_id(),
152 _target_refills, _allocation_fraction.average(), desired_size(), aligned_new_size);
153
154 set_desired_size(aligned_new_size);
155 set_refill_waste_limit(initial_refill_waste_limit());
156 }
157
158 void ThreadLocalAllocBuffer::initialize_statistics() {
159 _number_of_refills = 0;
160 _fast_refill_waste = 0;
161 _slow_refill_waste = 0;
162 _gc_waste = 0;
163 _slow_allocations = 0;
164 }
165
166 void ThreadLocalAllocBuffer::fill(HeapWord* start,
167 HeapWord* top,
168 size_t new_size) {
169 _number_of_refills++;
170 print_stats("fill");
171 assert(top <= start + new_size - alignment_reserve(), "size too small");
172 initialize(start, top, start + new_size - alignment_reserve());
173
174 // Reset amount of internal fragmentation
175 set_refill_waste_limit(initial_refill_waste_limit());
176 }
177
178 void ThreadLocalAllocBuffer::initialize(HeapWord* start,
179 HeapWord* top,
180 HeapWord* end) {
181 set_start(start);
182 set_top(top);
183 set_pf_top(top);
184 set_end(end);
185 invariants();
186 }
187
188 void ThreadLocalAllocBuffer::initialize() {
189 initialize(NULL, // start
190 NULL, // top
191 NULL); // end
192
193 set_desired_size(initial_desired_size());
194
195 // Following check is needed because at startup the main (primordial)
196 // thread is initialized before the heap is. The initialization for
197 // this thread is redone in startup_initialization below.
198 if (Universe::heap() != NULL) {
199 size_t capacity = Universe::heap()->tlab_capacity(myThread()) / HeapWordSize;
200 double alloc_frac = desired_size() * target_refills() / (double) capacity;
201 _allocation_fraction.sample(alloc_frac);
202 }
203
204 set_refill_waste_limit(initial_refill_waste_limit());
205
206 initialize_statistics();
207 }
208
209 void ThreadLocalAllocBuffer::startup_initialization() {
210
211 // Assuming each thread's active tlab is, on average,
212 // 1/2 full at a GC
213 _target_refills = 100 / (2 * TLABWasteTargetPercent);
214 _target_refills = MAX2(_target_refills, (unsigned)1U);
215
216 _global_stats = new GlobalTLABStats();
217
218 // During jvm startup, the main (primordial) thread is initialized
219 // before the heap is initialized. So reinitialize it now.
220 guarantee(Thread::current()->is_Java_thread(), "tlab initialization thread not Java thread");
221 Thread::current()->tlab().initialize();
222
223 log_develop(gc, tlab)("TLAB min: " SIZE_FORMAT " initial: " SIZE_FORMAT " max: " SIZE_FORMAT,
224 min_size(), Thread::current()->tlab().initial_desired_size(), max_size());
225 }
226
227 size_t ThreadLocalAllocBuffer::initial_desired_size() {
228 size_t init_sz = 0;
229
230 if (TLABSize > 0) {
231 init_sz = TLABSize / HeapWordSize;
232 } else if (global_stats() != NULL) {
233 // Initial size is a function of the average number of allocating threads.
234 unsigned nof_threads = global_stats()->allocating_threads_avg();
235
236 init_sz = (Universe::heap()->tlab_capacity(myThread()) / HeapWordSize) /
237 (nof_threads * target_refills());
238 init_sz = align_object_size(init_sz);
239 }
240 init_sz = MIN2(MAX2(init_sz, min_size()), max_size());
241 return init_sz;
242 }
243
244 void ThreadLocalAllocBuffer::print_stats(const char* tag) {
245 LogHandle(gc, tlab) log;
246 if (!log.is_trace()) {
247 return;
248 }
249
250 Thread* thrd = myThread();
251 size_t waste = _gc_waste + _slow_refill_waste + _fast_refill_waste;
252 size_t alloc = _number_of_refills * _desired_size;
253 double waste_percent = alloc == 0 ? 0.0 :
254 100.0 * waste / alloc;
255 size_t tlab_used = Universe::heap()->tlab_used(thrd);
256 log.trace("TLAB: %s thread: " INTPTR_FORMAT " [id: %2d]"
257 " desired_size: " SIZE_FORMAT "KB"
258 " slow allocs: %d refill waste: " SIZE_FORMAT "B"
259 " alloc:%8.5f %8.0fKB refills: %d waste %4.1f%% gc: %dB"
260 " slow: %dB fast: %dB",
261 tag, p2i(thrd), thrd->osthread()->thread_id(),
262 _desired_size / (K / HeapWordSize),
263 _slow_allocations, _refill_waste_limit * HeapWordSize,
264 _allocation_fraction.average(),
265 _allocation_fraction.average() * tlab_used / K,
266 _number_of_refills, waste_percent,
267 _gc_waste * HeapWordSize,
268 _slow_refill_waste * HeapWordSize,
269 _fast_refill_waste * HeapWordSize);
270 }
271
272 void ThreadLocalAllocBuffer::verify() {
273 HeapWord* p = start();
274 HeapWord* t = top();
275 HeapWord* prev_p = NULL;
276 while (p < t) {
277 oop(p)->verify();
278 prev_p = p;
279 p += oop(p)->size();
280 }
281 guarantee(p == top(), "end of last object must match end of space");
282 }
283
284 Thread* ThreadLocalAllocBuffer::myThread() {
285 return (Thread*)(((char *)this) +
286 in_bytes(start_offset()) -
287 in_bytes(Thread::tlab_start_offset()));
288 }
289
290
291 GlobalTLABStats::GlobalTLABStats() :
292 _allocating_threads_avg(TLABAllocationWeight) {
293
294 initialize();
295
296 _allocating_threads_avg.sample(1); // One allocating thread at startup
297
298 if (UsePerfData) {
299
300 EXCEPTION_MARK;
301 ResourceMark rm;
302
303 char* cname = PerfDataManager::counter_name("tlab", "allocThreads");
304 _perf_allocating_threads =
305 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
306
307 cname = PerfDataManager::counter_name("tlab", "fills");
308 _perf_total_refills =
309 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
310
311 cname = PerfDataManager::counter_name("tlab", "maxFills");
312 _perf_max_refills =
313 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
314
315 cname = PerfDataManager::counter_name("tlab", "alloc");
316 _perf_allocation =
317 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
318
319 cname = PerfDataManager::counter_name("tlab", "gcWaste");
320 _perf_gc_waste =
321 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
322
323 cname = PerfDataManager::counter_name("tlab", "maxGcWaste");
324 _perf_max_gc_waste =
325 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
326
327 cname = PerfDataManager::counter_name("tlab", "slowWaste");
328 _perf_slow_refill_waste =
329 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
330
331 cname = PerfDataManager::counter_name("tlab", "maxSlowWaste");
332 _perf_max_slow_refill_waste =
333 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
334
335 cname = PerfDataManager::counter_name("tlab", "fastWaste");
336 _perf_fast_refill_waste =
337 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
338
339 cname = PerfDataManager::counter_name("tlab", "maxFastWaste");
340 _perf_max_fast_refill_waste =
341 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
342
343 cname = PerfDataManager::counter_name("tlab", "slowAlloc");
344 _perf_slow_allocations =
345 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
346
347 cname = PerfDataManager::counter_name("tlab", "maxSlowAlloc");
348 _perf_max_slow_allocations =
349 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
350 }
351 }
352
353 void GlobalTLABStats::initialize() {
354 // Clear counters summarizing info from all threads
355 _allocating_threads = 0;
356 _total_refills = 0;
357 _max_refills = 0;
358 _total_allocation = 0;
359 _total_gc_waste = 0;
360 _max_gc_waste = 0;
361 _total_slow_refill_waste = 0;
362 _max_slow_refill_waste = 0;
363 _total_fast_refill_waste = 0;
364 _max_fast_refill_waste = 0;
365 _total_slow_allocations = 0;
366 _max_slow_allocations = 0;
367 }
368
369 void GlobalTLABStats::publish() {
370 _allocating_threads_avg.sample(_allocating_threads);
371 if (UsePerfData) {
372 _perf_allocating_threads ->set_value(_allocating_threads);
373 _perf_total_refills ->set_value(_total_refills);
374 _perf_max_refills ->set_value(_max_refills);
375 _perf_allocation ->set_value(_total_allocation);
376 _perf_gc_waste ->set_value(_total_gc_waste);
377 _perf_max_gc_waste ->set_value(_max_gc_waste);
378 _perf_slow_refill_waste ->set_value(_total_slow_refill_waste);
379 _perf_max_slow_refill_waste->set_value(_max_slow_refill_waste);
380 _perf_fast_refill_waste ->set_value(_total_fast_refill_waste);
381 _perf_max_fast_refill_waste->set_value(_max_fast_refill_waste);
382 _perf_slow_allocations ->set_value(_total_slow_allocations);
383 _perf_max_slow_allocations ->set_value(_max_slow_allocations);
384 }
385 }
386
387 void GlobalTLABStats::print() {
388 LogHandle(gc, tlab) log;
389 if (!log.is_debug()) {
390 return;
391 }
392
393 size_t waste = _total_gc_waste + _total_slow_refill_waste + _total_fast_refill_waste;
394 double waste_percent = _total_allocation == 0 ? 0.0 :
395 100.0 * waste / _total_allocation;
396 log.debug("TLAB totals: thrds: %d refills: %d max: %d"
397 " slow allocs: %d max %d waste: %4.1f%%"
398 " gc: " SIZE_FORMAT "B max: " SIZE_FORMAT "B"
399 " slow: " SIZE_FORMAT "B max: " SIZE_FORMAT "B"
400 " fast: " SIZE_FORMAT "B max: " SIZE_FORMAT "B",
401 _allocating_threads,
402 _total_refills, _max_refills,
403 _total_slow_allocations, _max_slow_allocations,
404 waste_percent,
405 _total_gc_waste * HeapWordSize,
406 _max_gc_waste * HeapWordSize,
407 _total_slow_refill_waste * HeapWordSize,
408 _max_slow_refill_waste * HeapWordSize,
409 _total_fast_refill_waste * HeapWordSize,
410 _max_fast_refill_waste * HeapWordSize);
411 }