1 /*
2 * Copyright (c) 2002, 2011, 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_implementation/parallelScavenge/parallelScavengeHeap.hpp"
27 #include "gc_implementation/parallelScavenge/psOldGen.hpp"
28 #include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp"
29 #include "gc_implementation/parallelScavenge/psScavenge.inline.hpp"
30 #include "gc_implementation/shared/mutableSpace.hpp"
31 #include "memory/memRegion.hpp"
32 #include "oops/oop.inline.hpp"
33 #include "oops/oop.psgc.inline.hpp"
34
35 PSPromotionManager** PSPromotionManager::_manager_array = NULL;
36 OopStarTaskQueueSet* PSPromotionManager::_stack_array_depth = NULL;
37 PSOldGen* PSPromotionManager::_old_gen = NULL;
38 MutableSpace* PSPromotionManager::_young_space = NULL;
39
40 void PSPromotionManager::initialize() {
41 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
42 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
43
44 _old_gen = heap->old_gen();
45 _young_space = heap->young_gen()->to_space();
46
47 assert(_manager_array == NULL, "Attempt to initialize twice");
48 _manager_array = NEW_C_HEAP_ARRAY(PSPromotionManager*, ParallelGCThreads+1 );
49 guarantee(_manager_array != NULL, "Could not initialize promotion manager");
50
51 _stack_array_depth = new OopStarTaskQueueSet(ParallelGCThreads);
52 guarantee(_stack_array_depth != NULL, "Cound not initialize promotion manager");
53
54 // Create and register the PSPromotionManager(s) for the worker threads.
55 for(uint i=0; i<ParallelGCThreads; i++) {
56 _manager_array[i] = new PSPromotionManager();
57 guarantee(_manager_array[i] != NULL, "Could not create PSPromotionManager");
58 stack_array_depth()->register_queue(i, _manager_array[i]->claimed_stack_depth());
59 }
60
61 // The VMThread gets its own PSPromotionManager, which is not available
62 // for work stealing.
63 _manager_array[ParallelGCThreads] = new PSPromotionManager();
64 guarantee(_manager_array[ParallelGCThreads] != NULL, "Could not create PSPromotionManager");
65 }
66
67 PSPromotionManager* PSPromotionManager::gc_thread_promotion_manager(int index) {
68 assert(index >= 0 && index < (int)ParallelGCThreads, "index out of range");
69 assert(_manager_array != NULL, "Sanity");
70 return _manager_array[index];
71 }
72
73 PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() {
74 assert(_manager_array != NULL, "Sanity");
75 return _manager_array[ParallelGCThreads];
76 }
77
78 void PSPromotionManager::pre_scavenge() {
79 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
80 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
81
82 _young_space = heap->young_gen()->to_space();
83
84 for(uint i=0; i<ParallelGCThreads+1; i++) {
85 manager_array(i)->reset();
86 }
87 }
88
89 void PSPromotionManager::post_scavenge() {
90 TASKQUEUE_STATS_ONLY(if (PrintGCDetails && ParallelGCVerbose) print_stats());
91 for (uint i = 0; i < ParallelGCThreads + 1; i++) {
92 PSPromotionManager* manager = manager_array(i);
93 assert(manager->claimed_stack_depth()->is_empty(), "should be empty");
94 manager->flush_labs();
95 }
96 }
97
98 #if TASKQUEUE_STATS
99 void
100 PSPromotionManager::print_taskqueue_stats(uint i) const {
101 tty->print("%3u ", i);
102 _claimed_stack_depth.stats.print();
103 tty->cr();
104 }
105
106 void
107 PSPromotionManager::print_local_stats(uint i) const {
108 #define FMT " " SIZE_FORMAT_W(10)
109 tty->print_cr("%3u" FMT FMT FMT FMT, i, _masked_pushes, _masked_steals,
110 _arrays_chunked, _array_chunks_processed);
111 #undef FMT
112 }
113
114 static const char* const pm_stats_hdr[] = {
115 " --------masked------- arrays array",
116 "thr push steal chunked chunks",
117 "--- ---------- ---------- ---------- ----------"
118 };
119
120 void
121 PSPromotionManager::print_stats() {
122 tty->print_cr("== GC Tasks Stats, GC %3d",
123 Universe::heap()->total_collections());
124
125 tty->print("thr "); TaskQueueStats::print_header(1); tty->cr();
126 tty->print("--- "); TaskQueueStats::print_header(2); tty->cr();
127 for (uint i = 0; i < ParallelGCThreads + 1; ++i) {
128 manager_array(i)->print_taskqueue_stats(i);
129 }
130
131 const uint hlines = sizeof(pm_stats_hdr) / sizeof(pm_stats_hdr[0]);
132 for (uint i = 0; i < hlines; ++i) tty->print_cr(pm_stats_hdr[i]);
133 for (uint i = 0; i < ParallelGCThreads + 1; ++i) {
134 manager_array(i)->print_local_stats(i);
135 }
136 }
137
138 void
139 PSPromotionManager::reset_stats() {
140 claimed_stack_depth()->stats.reset();
141 _masked_pushes = _masked_steals = 0;
142 _arrays_chunked = _array_chunks_processed = 0;
143 }
144 #endif // TASKQUEUE_STATS
145
146 PSPromotionManager::PSPromotionManager() {
147 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
148 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
149
150 // We set the old lab's start array.
151 _old_lab.set_start_array(old_gen()->start_array());
152
153 uint queue_size;
154 claimed_stack_depth()->initialize();
155 queue_size = claimed_stack_depth()->max_elems();
156
157 _totally_drain = (ParallelGCThreads == 1) || (GCDrainStackTargetSize == 0);
158 if (_totally_drain) {
159 _target_stack_size = 0;
160 } else {
161 // don't let the target stack size to be more than 1/4 of the entries
162 _target_stack_size = (uint) MIN2((uint) GCDrainStackTargetSize,
163 (uint) (queue_size / 4));
164 }
165
166 _array_chunk_size = ParGCArrayScanChunk;
167 // let's choose 1.5x the chunk size
168 _min_array_size_for_chunking = 3 * _array_chunk_size / 2;
169
170 reset();
171 }
172
173 void PSPromotionManager::reset() {
174 assert(stacks_empty(), "reset of non-empty stack");
175
176 // We need to get an assert in here to make sure the labs are always flushed.
177
178 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
179 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
180
181 // Do not prefill the LAB's, save heap wastage!
182 HeapWord* lab_base = young_space()->top();
183 _young_lab.initialize(MemRegion(lab_base, (size_t)0));
184 _young_gen_is_full = false;
185
186 lab_base = old_gen()->object_space()->top();
187 _old_lab.initialize(MemRegion(lab_base, (size_t)0));
188 _old_gen_is_full = false;
189
190 TASKQUEUE_STATS_ONLY(reset_stats());
191 }
192
193
194 void PSPromotionManager::drain_stacks_depth(bool totally_drain) {
195 totally_drain = totally_drain || _totally_drain;
196
197 #ifdef ASSERT
198 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
199 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
200 MutableSpace* to_space = heap->young_gen()->to_space();
201 MutableSpace* old_space = heap->old_gen()->object_space();
202 MutableSpace* perm_space = heap->perm_gen()->object_space();
203 #endif /* ASSERT */
204
205 OopStarTaskQueue* const tq = claimed_stack_depth();
206 do {
207 StarTask p;
208
209 // Drain overflow stack first, so other threads can steal from
210 // claimed stack while we work.
211 while (tq->pop_overflow(p)) {
212 process_popped_location_depth(p);
213 }
214
215 if (totally_drain) {
216 while (tq->pop_local(p)) {
217 process_popped_location_depth(p);
218 }
219 } else {
220 while (tq->size() > _target_stack_size && tq->pop_local(p)) {
221 process_popped_location_depth(p);
222 }
223 }
224 } while (totally_drain && !tq->taskqueue_empty() || !tq->overflow_empty());
225
226 assert(!totally_drain || tq->taskqueue_empty(), "Sanity");
227 assert(totally_drain || tq->size() <= _target_stack_size, "Sanity");
228 assert(tq->overflow_empty(), "Sanity");
229 }
230
231 void PSPromotionManager::flush_labs() {
232 assert(stacks_empty(), "Attempt to flush lab with live stack");
233
234 // If either promotion lab fills up, we can flush the
235 // lab but not refill it, so check first.
236 assert(!_young_lab.is_flushed() || _young_gen_is_full, "Sanity");
237 if (!_young_lab.is_flushed())
238 _young_lab.flush();
239
240 assert(!_old_lab.is_flushed() || _old_gen_is_full, "Sanity");
241 if (!_old_lab.is_flushed())
242 _old_lab.flush();
243
244 // Let PSScavenge know if we overflowed
245 if (_young_gen_is_full) {
246 PSScavenge::set_survivor_overflow(true);
247 }
248 }
249
250 //
251 // This method is pretty bulky. It would be nice to split it up
252 // into smaller submethods, but we need to be careful not to hurt
253 // performance.
254 //
255
256 oop PSPromotionManager::copy_to_survivor_space(oop o) {
257 assert(PSScavenge::should_scavenge(&o), "Sanity");
258
259 oop new_obj = NULL;
260
261 // NOTE! We must be very careful with any methods that access the mark
262 // in o. There may be multiple threads racing on it, and it may be forwarded
263 // at any time. Do not use oop methods for accessing the mark!
264 markOop test_mark = o->mark();
265
266 // The same test as "o->is_forwarded()"
267 if (!test_mark->is_marked()) {
268 bool new_obj_is_tenured = false;
269 size_t new_obj_size = o->size();
270
271 // Find the objects age, MT safe.
272 int age = (test_mark->has_displaced_mark_helper() /* o->has_displaced_mark() */) ?
273 test_mark->displaced_mark_helper()->age() : test_mark->age();
274
275 // Try allocating obj in to-space (unless too old)
276 if (age < PSScavenge::tenuring_threshold()) {
277 new_obj = (oop) _young_lab.allocate(new_obj_size);
278 if (new_obj == NULL && !_young_gen_is_full) {
279 // Do we allocate directly, or flush and refill?
280 if (new_obj_size > (YoungPLABSize / 2)) {
281 // Allocate this object directly
282 new_obj = (oop)young_space()->cas_allocate(new_obj_size);
283 } else {
284 // Flush and fill
285 _young_lab.flush();
286
287 HeapWord* lab_base = young_space()->cas_allocate(YoungPLABSize);
288 if (lab_base != NULL) {
289 _young_lab.initialize(MemRegion(lab_base, YoungPLABSize));
290 // Try the young lab allocation again.
291 new_obj = (oop) _young_lab.allocate(new_obj_size);
292 } else {
293 _young_gen_is_full = true;
294 }
295 }
296 }
297 }
298
299 // Otherwise try allocating obj tenured
300 if (new_obj == NULL) {
301 #ifndef PRODUCT
302 if (Universe::heap()->promotion_should_fail()) {
303 return oop_promotion_failed(o, test_mark);
304 }
305 #endif // #ifndef PRODUCT
306
307 new_obj = (oop) _old_lab.allocate(new_obj_size);
308 new_obj_is_tenured = true;
309
310 if (new_obj == NULL) {
311 if (!_old_gen_is_full) {
312 // Do we allocate directly, or flush and refill?
313 if (new_obj_size > (OldPLABSize / 2)) {
314 // Allocate this object directly
315 new_obj = (oop)old_gen()->cas_allocate(new_obj_size);
316 } else {
317 // Flush and fill
318 _old_lab.flush();
319
320 HeapWord* lab_base = old_gen()->cas_allocate(OldPLABSize);
321 if(lab_base != NULL) {
322 _old_lab.initialize(MemRegion(lab_base, OldPLABSize));
323 // Try the old lab allocation again.
324 new_obj = (oop) _old_lab.allocate(new_obj_size);
325 }
326 }
327 }
328
329 // This is the promotion failed test, and code handling.
330 // The code belongs here for two reasons. It is slightly
331 // different thatn the code below, and cannot share the
332 // CAS testing code. Keeping the code here also minimizes
333 // the impact on the common case fast path code.
334
335 if (new_obj == NULL) {
336 _old_gen_is_full = true;
337 return oop_promotion_failed(o, test_mark);
338 }
339 }
340 }
341
342 assert(new_obj != NULL, "allocation should have succeeded");
343
344 // Copy obj
345 Copy::aligned_disjoint_words((HeapWord*)o, (HeapWord*)new_obj, new_obj_size);
346
347 // Now we have to CAS in the header.
348 if (o->cas_forward_to(new_obj, test_mark)) {
349 // We won any races, we "own" this object.
350 assert(new_obj == o->forwardee(), "Sanity");
351
352 // Increment age if obj still in new generation. Now that
353 // we're dealing with a markOop that cannot change, it is
354 // okay to use the non mt safe oop methods.
355 if (!new_obj_is_tenured) {
356 new_obj->incr_age();
357 assert(young_space()->contains(new_obj), "Attempt to push non-promoted obj");
358 }
359
360 // Do the size comparison first with new_obj_size, which we
361 // already have. Hopefully, only a few objects are larger than
362 // _min_array_size_for_chunking, and most of them will be arrays.
363 // So, the is->objArray() test would be very infrequent.
364 if (new_obj_size > _min_array_size_for_chunking &&
365 new_obj->is_objArray() &&
366 PSChunkLargeArrays) {
367 // we'll chunk it
368 oop* const masked_o = mask_chunked_array_oop(o);
369 push_depth(masked_o);
370 TASKQUEUE_STATS_ONLY(++_arrays_chunked; ++_masked_pushes);
371 } else {
372 // we'll just push its contents
373 new_obj->push_contents(this);
374 }
375 } else {
376 // We lost, someone else "owns" this object
377 guarantee(o->is_forwarded(), "Object must be forwarded if the cas failed.");
378
379 // Try to deallocate the space. If it was directly allocated we cannot
380 // deallocate it, so we have to test. If the deallocation fails,
381 // overwrite with a filler object.
382 if (new_obj_is_tenured) {
383 if (!_old_lab.unallocate_object((HeapWord*) new_obj, new_obj_size)) {
384 CollectedHeap::fill_with_object((HeapWord*) new_obj, new_obj_size);
385 }
386 } else if (!_young_lab.unallocate_object((HeapWord*) new_obj, new_obj_size)) {
387 CollectedHeap::fill_with_object((HeapWord*) new_obj, new_obj_size);
388 }
389
390 // don't update this before the unallocation!
391 new_obj = o->forwardee();
392 }
393 } else {
394 assert(o->is_forwarded(), "Sanity");
395 new_obj = o->forwardee();
396 }
397
398 #ifdef DEBUG
399 // This code must come after the CAS test, or it will print incorrect
400 // information.
401 if (TraceScavenge) {
402 gclog_or_tty->print_cr("{%s %s " PTR_FORMAT " -> " PTR_FORMAT " (" SIZE_FORMAT ")}",
403 PSScavenge::should_scavenge(&new_obj) ? "copying" : "tenuring",
404 new_obj->blueprint()->internal_name(), o, new_obj, new_obj->size());
405 }
406 #endif
407
408 return new_obj;
409 }
410
411 template <class T> void PSPromotionManager::process_array_chunk_work(
412 oop obj,
413 int start, int end) {
414 assert(start <= end, "invariant");
415 T* const base = (T*)objArrayOop(obj)->base();
416 T* p = base + start;
417 T* const chunk_end = base + end;
418 while (p < chunk_end) {
419 if (PSScavenge::should_scavenge(p)) {
420 claim_or_forward_depth(p);
421 }
422 ++p;
423 }
424 }
425
426 void PSPromotionManager::process_array_chunk(oop old) {
427 assert(PSChunkLargeArrays, "invariant");
428 assert(old->is_objArray(), "invariant");
429 assert(old->is_forwarded(), "invariant");
430
431 TASKQUEUE_STATS_ONLY(++_array_chunks_processed);
432
433 oop const obj = old->forwardee();
434
435 int start;
436 int const end = arrayOop(old)->length();
437 if (end > (int) _min_array_size_for_chunking) {
438 // we'll chunk more
439 start = end - _array_chunk_size;
440 assert(start > 0, "invariant");
441 arrayOop(old)->set_length(start);
442 push_depth(mask_chunked_array_oop(old));
443 TASKQUEUE_STATS_ONLY(++_masked_pushes);
444 } else {
445 // this is the final chunk for this array
446 start = 0;
447 int const actual_length = arrayOop(obj)->length();
448 arrayOop(old)->set_length(actual_length);
449 }
450
451 if (UseCompressedOops) {
452 process_array_chunk_work<narrowOop>(obj, start, end);
453 } else {
454 process_array_chunk_work<oop>(obj, start, end);
455 }
456 }
457
458 oop PSPromotionManager::oop_promotion_failed(oop obj, markOop obj_mark) {
459 assert(_old_gen_is_full || PromotionFailureALot, "Sanity");
460
461 // Attempt to CAS in the header.
462 // This tests if the header is still the same as when
463 // this started. If it is the same (i.e., no forwarding
464 // pointer has been installed), then this thread owns
465 // it.
466 if (obj->cas_forward_to(obj, obj_mark)) {
467 // We won any races, we "own" this object.
468 assert(obj == obj->forwardee(), "Sanity");
469
470 obj->push_contents(this);
471
472 // Save the mark if needed
473 PSScavenge::oop_promotion_failed(obj, obj_mark);
474 } else {
475 // We lost, someone else "owns" this object
476 guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed.");
477
478 // No unallocation to worry about.
479 obj = obj->forwardee();
480 }
481
482 #ifdef DEBUG
483 if (TraceScavenge) {
484 gclog_or_tty->print_cr("{%s %s 0x%x (%d)}",
485 "promotion-failure",
486 obj->blueprint()->internal_name(),
487 obj, obj->size());
488
489 }
490 #endif
491
492 return obj;
493 }