1 /*
2 * Copyright (c) 1999, 2017, 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 int ThreadLocalAllocBuffer::_reserve_for_allocation_prefetch = 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 assert(!ZapUnusedHeapArea || _reserve_for_allocation_prefetch > 0 ||
46 top() == NULL || *(intptr_t*)top() != 0, "overzeroing detected");
47 make_parsable(true); // also retire the TLAB
48 }
49
50 void ThreadLocalAllocBuffer::accumulate_statistics_before_gc() {
51 global_stats()->initialize();
52
53 for (JavaThread *thread = Threads::first(); thread != NULL; thread = thread->next()) {
54 thread->tlab().accumulate_statistics();
55 thread->tlab().initialize_statistics();
56 }
57
58 // Publish new stats if some allocation occurred.
59 if (global_stats()->allocation() != 0) {
60 global_stats()->publish();
61 global_stats()->print();
62 }
63 }
64
65 void ThreadLocalAllocBuffer::accumulate_statistics() {
66 Thread* thread = myThread();
67 size_t capacity = Universe::heap()->tlab_capacity(thread);
68 size_t used = Universe::heap()->tlab_used(thread);
69
70 _gc_waste += (unsigned)remaining();
71 size_t total_allocated = thread->allocated_bytes();
72 size_t allocated_since_last_gc = total_allocated - _allocated_before_last_gc;
73 _allocated_before_last_gc = total_allocated;
74
75 print_stats("gc");
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, bool zap) {
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 && zap);
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 log_trace(gc, tlab)("TLAB new size: thread: " INTPTR_FORMAT " [id: %2d]"
153 " refills %d alloc: %8.6f desired_size: " SIZE_FORMAT " -> " SIZE_FORMAT,
154 p2i(myThread()), myThread()->osthread()->thread_id(),
155 _target_refills, _allocation_fraction.average(), desired_size(), aligned_new_size);
156
157 set_desired_size(aligned_new_size);
158 set_refill_waste_limit(initial_refill_waste_limit());
159 }
160
161 void ThreadLocalAllocBuffer::initialize_statistics() {
162 _number_of_refills = 0;
163 _fast_refill_waste = 0;
164 _slow_refill_waste = 0;
165 _gc_waste = 0;
166 _slow_allocations = 0;
167 }
168
169 void ThreadLocalAllocBuffer::fill(HeapWord* start,
170 HeapWord* top,
171 size_t new_size) {
172 _number_of_refills++;
173 print_stats("fill");
174 assert(top <= start + new_size - alignment_reserve(), "size too small");
175 initialize(start, top, start + new_size - alignment_reserve());
176
177 // Reset amount of internal fragmentation
178 set_refill_waste_limit(initial_refill_waste_limit());
179 }
180
181 void ThreadLocalAllocBuffer::initialize(HeapWord* start,
182 HeapWord* top,
183 HeapWord* end) {
184 set_start(start);
185 set_top(top);
186 set_pf_top(top);
187 set_end(end);
188 invariants();
189 }
190
191 void ThreadLocalAllocBuffer::initialize() {
192 initialize(NULL, // start
193 NULL, // top
194 NULL); // end
195
196 set_desired_size(initial_desired_size());
197
198 // Following check is needed because at startup the main (primordial)
199 // thread is initialized before the heap is. The initialization for
200 // this thread is redone in startup_initialization below.
201 if (Universe::heap() != NULL) {
202 size_t capacity = Universe::heap()->tlab_capacity(myThread()) / HeapWordSize;
203 double alloc_frac = desired_size() * target_refills() / (double) capacity;
204 _allocation_fraction.sample(alloc_frac);
205 }
206
207 set_refill_waste_limit(initial_refill_waste_limit());
208
209 initialize_statistics();
210 }
211
212 void ThreadLocalAllocBuffer::startup_initialization() {
213
214 // Assuming each thread's active tlab is, on average,
215 // 1/2 full at a GC
216 _target_refills = 100 / (2 * TLABWasteTargetPercent);
217 _target_refills = MAX2(_target_refills, (unsigned)1U);
218
219 _global_stats = new GlobalTLABStats();
220
221 #ifdef COMPILER2
222 // If the C2 compiler is present, extra space is needed at the end of
223 // TLABs, otherwise prefetching instructions generated by the C2
224 // compiler will fault (due to accessing memory outside of heap).
225 // The amount of space is the max of the number of lines to
226 // prefetch for array and for instance allocations. (Extra space must be
227 // reserved to accommodate both types of allocations.)
228 //
229 // Only SPARC-specific BIS instructions are known to fault. (Those
230 // instructions are generated if AllocatePrefetchStyle==3 and
231 // AllocatePrefetchInstr==1). To be on the safe side, however,
232 // extra space is reserved for all combinations of
233 // AllocatePrefetchStyle and AllocatePrefetchInstr.
234 //
235 // If the C2 compiler is not present, no space is reserved.
236
237 // +1 for rounding up to next cache line, +1 to be safe
238 int lines = MAX2(AllocatePrefetchLines, AllocateInstancePrefetchLines) + 2;
239 _reserve_for_allocation_prefetch = (AllocatePrefetchDistance + AllocatePrefetchStepSize * lines) /
240 (int)HeapWordSize;
241 #endif
242
243 // During jvm startup, the main (primordial) thread is initialized
244 // before the heap is initialized. So reinitialize it now.
245 guarantee(Thread::current()->is_Java_thread(), "tlab initialization thread not Java thread");
246 Thread::current()->tlab().initialize();
247
248 log_develop_trace(gc, tlab)("TLAB min: " SIZE_FORMAT " initial: " SIZE_FORMAT " max: " SIZE_FORMAT,
249 min_size(), Thread::current()->tlab().initial_desired_size(), max_size());
250 }
251
252 size_t ThreadLocalAllocBuffer::initial_desired_size() {
253 size_t init_sz = 0;
254
255 if (TLABSize > 0) {
256 init_sz = TLABSize / HeapWordSize;
257 } else if (global_stats() != NULL) {
258 // Initial size is a function of the average number of allocating threads.
259 unsigned nof_threads = global_stats()->allocating_threads_avg();
260
261 init_sz = (Universe::heap()->tlab_capacity(myThread()) / HeapWordSize) /
262 (nof_threads * target_refills());
263 init_sz = align_object_size(init_sz);
264 }
265 init_sz = MIN2(MAX2(init_sz, min_size()), max_size());
266 return init_sz;
267 }
268
269 void ThreadLocalAllocBuffer::print_stats(const char* tag) {
270 Log(gc, tlab) log;
271 if (!log.is_trace()) {
272 return;
273 }
274
275 Thread* thrd = myThread();
276 size_t waste = _gc_waste + _slow_refill_waste + _fast_refill_waste;
277 size_t alloc = _number_of_refills * _desired_size;
278 double waste_percent = alloc == 0 ? 0.0 :
279 100.0 * waste / alloc;
280 size_t tlab_used = Universe::heap()->tlab_used(thrd);
281 log.trace("TLAB: %s thread: " INTPTR_FORMAT " [id: %2d]"
282 " desired_size: " SIZE_FORMAT "KB"
283 " slow allocs: %d refill waste: " SIZE_FORMAT "B"
284 " alloc:%8.5f %8.0fKB refills: %d waste %4.1f%% gc: %dB"
285 " slow: %dB fast: %dB",
286 tag, p2i(thrd), thrd->osthread()->thread_id(),
287 _desired_size / (K / HeapWordSize),
288 _slow_allocations, _refill_waste_limit * HeapWordSize,
289 _allocation_fraction.average(),
290 _allocation_fraction.average() * tlab_used / K,
291 _number_of_refills, waste_percent,
292 _gc_waste * HeapWordSize,
293 _slow_refill_waste * HeapWordSize,
294 _fast_refill_waste * HeapWordSize);
295 }
296
297 void ThreadLocalAllocBuffer::verify() {
298 HeapWord* p = start();
299 HeapWord* t = top();
300 HeapWord* prev_p = NULL;
301 while (p < t) {
302 oop(p)->verify();
303 prev_p = p;
304 p += oop(p)->size();
305 }
306 guarantee(p == top(), "end of last object must match end of space");
307 }
308
309 Thread* ThreadLocalAllocBuffer::myThread() {
310 return (Thread*)(((char *)this) +
311 in_bytes(start_offset()) -
312 in_bytes(Thread::tlab_start_offset()));
313 }
314
315
316 GlobalTLABStats::GlobalTLABStats() :
317 _allocating_threads_avg(TLABAllocationWeight) {
318
319 initialize();
320
321 _allocating_threads_avg.sample(1); // One allocating thread at startup
322
323 if (UsePerfData) {
324
325 EXCEPTION_MARK;
326 ResourceMark rm;
327
328 char* cname = PerfDataManager::counter_name("tlab", "allocThreads");
329 _perf_allocating_threads =
330 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
331
332 cname = PerfDataManager::counter_name("tlab", "fills");
333 _perf_total_refills =
334 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
335
336 cname = PerfDataManager::counter_name("tlab", "maxFills");
337 _perf_max_refills =
338 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
339
340 cname = PerfDataManager::counter_name("tlab", "alloc");
341 _perf_allocation =
342 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
343
344 cname = PerfDataManager::counter_name("tlab", "gcWaste");
345 _perf_gc_waste =
346 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
347
348 cname = PerfDataManager::counter_name("tlab", "maxGcWaste");
349 _perf_max_gc_waste =
350 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
351
352 cname = PerfDataManager::counter_name("tlab", "slowWaste");
353 _perf_slow_refill_waste =
354 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
355
356 cname = PerfDataManager::counter_name("tlab", "maxSlowWaste");
357 _perf_max_slow_refill_waste =
358 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
359
360 cname = PerfDataManager::counter_name("tlab", "fastWaste");
361 _perf_fast_refill_waste =
362 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
363
364 cname = PerfDataManager::counter_name("tlab", "maxFastWaste");
365 _perf_max_fast_refill_waste =
366 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes, CHECK);
367
368 cname = PerfDataManager::counter_name("tlab", "slowAlloc");
369 _perf_slow_allocations =
370 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
371
372 cname = PerfDataManager::counter_name("tlab", "maxSlowAlloc");
373 _perf_max_slow_allocations =
374 PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_None, CHECK);
375 }
376 }
377
378 void GlobalTLABStats::initialize() {
379 // Clear counters summarizing info from all threads
380 _allocating_threads = 0;
381 _total_refills = 0;
382 _max_refills = 0;
383 _total_allocation = 0;
384 _total_gc_waste = 0;
385 _max_gc_waste = 0;
386 _total_slow_refill_waste = 0;
387 _max_slow_refill_waste = 0;
388 _total_fast_refill_waste = 0;
389 _max_fast_refill_waste = 0;
390 _total_slow_allocations = 0;
391 _max_slow_allocations = 0;
392 }
393
394 void GlobalTLABStats::publish() {
395 _allocating_threads_avg.sample(_allocating_threads);
396 if (UsePerfData) {
397 _perf_allocating_threads ->set_value(_allocating_threads);
398 _perf_total_refills ->set_value(_total_refills);
399 _perf_max_refills ->set_value(_max_refills);
400 _perf_allocation ->set_value(_total_allocation);
401 _perf_gc_waste ->set_value(_total_gc_waste);
402 _perf_max_gc_waste ->set_value(_max_gc_waste);
403 _perf_slow_refill_waste ->set_value(_total_slow_refill_waste);
404 _perf_max_slow_refill_waste->set_value(_max_slow_refill_waste);
405 _perf_fast_refill_waste ->set_value(_total_fast_refill_waste);
406 _perf_max_fast_refill_waste->set_value(_max_fast_refill_waste);
407 _perf_slow_allocations ->set_value(_total_slow_allocations);
408 _perf_max_slow_allocations ->set_value(_max_slow_allocations);
409 }
410 }
411
412 void GlobalTLABStats::print() {
413 Log(gc, tlab) log;
414 if (!log.is_debug()) {
415 return;
416 }
417
418 size_t waste = _total_gc_waste + _total_slow_refill_waste + _total_fast_refill_waste;
419 double waste_percent = _total_allocation == 0 ? 0.0 :
420 100.0 * waste / _total_allocation;
421 log.debug("TLAB totals: thrds: %d refills: %d max: %d"
422 " slow allocs: %d max %d waste: %4.1f%%"
423 " gc: " SIZE_FORMAT "B max: " SIZE_FORMAT "B"
424 " slow: " SIZE_FORMAT "B max: " SIZE_FORMAT "B"
425 " fast: " SIZE_FORMAT "B max: " SIZE_FORMAT "B",
426 _allocating_threads,
427 _total_refills, _max_refills,
428 _total_slow_allocations, _max_slow_allocations,
429 waste_percent,
430 _total_gc_waste * HeapWordSize,
431 _max_gc_waste * HeapWordSize,
432 _total_slow_refill_waste * HeapWordSize,
433 _max_slow_refill_waste * HeapWordSize,
434 _total_fast_refill_waste * HeapWordSize,
435 _max_fast_refill_waste * HeapWordSize);
436 }