1 /*
2 * Copyright (c) 2011, 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_implementation/g1/g1CollectedHeap.inline.hpp"
27 #include "gc_implementation/g1/heapRegionRemSet.hpp"
28 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
29
30 uint FreeRegionList::_unrealistically_long_length = 0;
31
32 void HeapRegionSetBase::fill_in_ext_msg(hrs_ext_msg* msg, const char* message) {
33 msg->append("[%s] %s ln: %u cy: "SIZE_FORMAT,
34 name(), message, length(), total_capacity_bytes());
35 fill_in_ext_msg_extra(msg);
36 }
37
38 #ifndef PRODUCT
39 void HeapRegionSetBase::verify_region(HeapRegion* hr) {
40 assert(hr->containing_set() == this, err_msg("Inconsistent containing set for %u", hr->hrm_index()));
41 assert(!hr->is_young(), err_msg("Adding young region %u", hr->hrm_index())); // currently we don't use these sets for young regions
42 assert(hr->is_humongous() == regions_humongous(), err_msg("Wrong humongous state for region %u and set %s", hr->hrm_index(), name()));
43 assert(hr->is_free() == regions_free(), err_msg("Wrong free state for region %u and set %s", hr->hrm_index(), name()));
44 assert(!hr->is_free() || hr->is_empty(), err_msg("Free region %u is not empty for set %s", hr->hrm_index(), name()));
45 assert(!hr->is_empty() || hr->is_free(), err_msg("Empty region %u is not free for set %s", hr->hrm_index(), name()));
46 assert(hr->rem_set()->verify_ready_for_par_iteration(), err_msg("Wrong iteration state %u", hr->hrm_index()));
47 }
48 #endif
49
50 void HeapRegionSetBase::verify() {
51 // It's important that we also observe the MT safety protocol even
52 // for the verification calls. If we do verification without the
53 // appropriate locks and the set changes underneath our feet
54 // verification might fail and send us on a wild goose chase.
55 check_mt_safety();
56
57 guarantee(( is_empty() && length() == 0 && total_capacity_bytes() == 0) ||
58 (!is_empty() && length() > 0 && total_capacity_bytes() > 0) ,
59 hrs_ext_msg(this, "invariant"));
60 }
61
62 void HeapRegionSetBase::verify_start() {
63 // See comment in verify() about MT safety and verification.
64 check_mt_safety();
65 assert(!_verify_in_progress,
66 hrs_ext_msg(this, "verification should not be in progress"));
67
68 // Do the basic verification first before we do the checks over the regions.
69 HeapRegionSetBase::verify();
70
71 _verify_in_progress = true;
72 }
73
74 void HeapRegionSetBase::verify_end() {
75 // See comment in verify() about MT safety and verification.
76 check_mt_safety();
77 assert(_verify_in_progress,
78 hrs_ext_msg(this, "verification should be in progress"));
79
80 _verify_in_progress = false;
81 }
82
83 void HeapRegionSetBase::print_on(outputStream* out, bool print_contents) {
84 out->cr();
85 out->print_cr("Set: %s ("PTR_FORMAT")", name(), p2i(this));
86 out->print_cr(" Region Assumptions");
87 out->print_cr(" humongous : %s", BOOL_TO_STR(regions_humongous()));
88 out->print_cr(" free : %s", BOOL_TO_STR(regions_free()));
89 out->print_cr(" Attributes");
90 out->print_cr(" length : %14u", length());
91 out->print_cr(" total capacity : "SIZE_FORMAT_W(14)" bytes",
92 total_capacity_bytes());
93 }
94
95 HeapRegionSetBase::HeapRegionSetBase(const char* name, bool humongous, bool free, HRSMtSafeChecker* mt_safety_checker)
96 : _name(name), _verify_in_progress(false),
97 _is_humongous(humongous), _is_free(free), _mt_safety_checker(mt_safety_checker),
98 _count()
99 { }
100
101 void FreeRegionList::set_unrealistically_long_length(uint len) {
102 guarantee(_unrealistically_long_length == 0, "should only be set once");
103 _unrealistically_long_length = len;
104 }
105
106 void FreeRegionList::fill_in_ext_msg_extra(hrs_ext_msg* msg) {
107 msg->append(" hd: "PTR_FORMAT" tl: "PTR_FORMAT, p2i(_head), p2i(_tail));
108 }
109
110 void FreeRegionList::remove_all() {
111 check_mt_safety();
112 verify_optional();
113
114 HeapRegion* curr = _head;
115 while (curr != NULL) {
116 verify_region(curr);
117
118 HeapRegion* next = curr->next();
119 curr->set_next(NULL);
120 curr->set_prev(NULL);
121 curr->set_containing_set(NULL);
122 curr = next;
123 }
124 clear();
125
126 verify_optional();
127 }
128
129 void FreeRegionList::add_ordered(FreeRegionList* from_list) {
130 check_mt_safety();
131 from_list->check_mt_safety();
132
133 verify_optional();
134 from_list->verify_optional();
135
136 if (from_list->is_empty()) {
137 return;
138 }
139
140 #ifdef ASSERT
141 FreeRegionListIterator iter(from_list);
142 while (iter.more_available()) {
143 HeapRegion* hr = iter.get_next();
144 // In set_containing_set() we check that we either set the value
145 // from NULL to non-NULL or vice versa to catch bugs. So, we have
146 // to NULL it first before setting it to the value.
147 hr->set_containing_set(NULL);
148 hr->set_containing_set(this);
149 }
150 #endif // ASSERT
151
152 if (is_empty()) {
153 assert(length() == 0 && _tail == NULL, hrs_ext_msg(this, "invariant"));
154 _head = from_list->_head;
155 _tail = from_list->_tail;
156 } else {
157 HeapRegion* curr_to = _head;
158 HeapRegion* curr_from = from_list->_head;
159
160 while (curr_from != NULL) {
161 while (curr_to != NULL && curr_to->hrm_index() < curr_from->hrm_index()) {
162 curr_to = curr_to->next();
163 }
164
165 if (curr_to == NULL) {
166 // The rest of the from list should be added as tail
167 _tail->set_next(curr_from);
168 curr_from->set_prev(_tail);
169 curr_from = NULL;
170 } else {
171 HeapRegion* next_from = curr_from->next();
172
173 curr_from->set_next(curr_to);
174 curr_from->set_prev(curr_to->prev());
175 if (curr_to->prev() == NULL) {
176 _head = curr_from;
177 } else {
178 curr_to->prev()->set_next(curr_from);
179 }
180 curr_to->set_prev(curr_from);
181
182 curr_from = next_from;
183 }
184 }
185
186 if (_tail->hrm_index() < from_list->_tail->hrm_index()) {
187 _tail = from_list->_tail;
188 }
189 }
190
191 _count.increment(from_list->length(), from_list->total_capacity_bytes());
192 from_list->clear();
193
194 verify_optional();
195 from_list->verify_optional();
196 }
197
198 void FreeRegionList::remove_starting_at(HeapRegion* first, uint num_regions) {
199 check_mt_safety();
200 assert(num_regions >= 1, hrs_ext_msg(this, "pre-condition"));
201 assert(!is_empty(), hrs_ext_msg(this, "pre-condition"));
202
203 verify_optional();
204 DEBUG_ONLY(uint old_length = length();)
205
206 HeapRegion* curr = first;
207 uint count = 0;
208 while (count < num_regions) {
209 verify_region(curr);
210 HeapRegion* next = curr->next();
211 HeapRegion* prev = curr->prev();
212
213 assert(count < num_regions,
214 hrs_err_msg("[%s] should not come across more regions "
215 "pending for removal than num_regions: %u",
216 name(), num_regions));
217
218 if (prev == NULL) {
219 assert(_head == curr, hrs_ext_msg(this, "invariant"));
220 _head = next;
221 } else {
222 assert(_head != curr, hrs_ext_msg(this, "invariant"));
223 prev->set_next(next);
224 }
225 if (next == NULL) {
226 assert(_tail == curr, hrs_ext_msg(this, "invariant"));
227 _tail = prev;
228 } else {
229 assert(_tail != curr, hrs_ext_msg(this, "invariant"));
230 next->set_prev(prev);
231 }
232 if (_last = curr) {
233 _last = NULL;
234 }
235
236 curr->set_next(NULL);
237 curr->set_prev(NULL);
238 remove(curr);
239
240 count++;
241 curr = next;
242 }
243
244 assert(count == num_regions,
245 hrs_err_msg("[%s] count: %u should be == num_regions: %u",
246 name(), count, num_regions));
247 assert(length() + num_regions == old_length,
248 hrs_err_msg("[%s] new length should be consistent "
249 "new length: %u old length: %u num_regions: %u",
250 name(), length(), old_length, num_regions));
251
252 verify_optional();
253 }
254
255 void FreeRegionList::verify() {
256 // See comment in HeapRegionSetBase::verify() about MT safety and
257 // verification.
258 check_mt_safety();
259
260 // This will also do the basic verification too.
261 verify_start();
262
263 verify_list();
264
265 verify_end();
266 }
267
268 void FreeRegionList::clear() {
269 _count = HeapRegionSetCount();
270 _head = NULL;
271 _tail = NULL;
272 _last = NULL;
273 }
274
275 void FreeRegionList::print_on(outputStream* out, bool print_contents) {
276 HeapRegionSetBase::print_on(out, print_contents);
277 out->print_cr(" Linking");
278 out->print_cr(" head : "PTR_FORMAT, p2i(_head));
279 out->print_cr(" tail : "PTR_FORMAT, p2i(_tail));
280
281 if (print_contents) {
282 out->print_cr(" Contents");
283 FreeRegionListIterator iter(this);
284 while (iter.more_available()) {
285 HeapRegion* hr = iter.get_next();
286 hr->print_on(out);
287 }
288 }
289
290 out->cr();
291 }
292
293 void FreeRegionList::verify_list() {
294 HeapRegion* curr = _head;
295 HeapRegion* prev1 = NULL;
296 HeapRegion* prev0 = NULL;
297 uint count = 0;
298 size_t capacity = 0;
299 uint last_index = 0;
300
301 guarantee(_head == NULL || _head->prev() == NULL, "_head should not have a prev");
302 while (curr != NULL) {
303 verify_region(curr);
304
305 count++;
306 guarantee(count < _unrealistically_long_length,
307 hrs_err_msg("[%s] the calculated length: %u seems very long, is there maybe a cycle? curr: "PTR_FORMAT" prev0: "PTR_FORMAT" " "prev1: "PTR_FORMAT" length: %u",
308 name(), count, p2i(curr), p2i(prev0), p2i(prev1), length()));
309
310 if (curr->next() != NULL) {
311 guarantee(curr->next()->prev() == curr, "Next or prev pointers messed up");
312 }
313 guarantee(curr->hrm_index() == 0 || curr->hrm_index() > last_index, "List should be sorted");
314 last_index = curr->hrm_index();
315
316 capacity += curr->capacity();
317
318 prev1 = prev0;
319 prev0 = curr;
320 curr = curr->next();
321 }
322
323 guarantee(_tail == prev0, err_msg("Expected %s to end with %u but it ended with %u.", name(), _tail->hrm_index(), prev0->hrm_index()));
324 guarantee(_tail == NULL || _tail->next() == NULL, "_tail should not have a next");
325 guarantee(length() == count, err_msg("%s count mismatch. Expected %u, actual %u.", name(), length(), count));
326 guarantee(total_capacity_bytes() == capacity, err_msg("%s capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
327 name(), total_capacity_bytes(), capacity));
328 }
329
330 // Note on the check_mt_safety() methods below:
331 //
332 // Verification of the "master" heap region sets / lists that are
333 // maintained by G1CollectedHeap is always done during a STW pause and
334 // by the VM thread at the start / end of the pause. The standard
335 // verification methods all assert check_mt_safety(). This is
336 // important as it ensures that verification is done without
337 // concurrent updates taking place at the same time. It follows, that,
338 // for the "master" heap region sets / lists, the check_mt_safety()
339 // method should include the VM thread / STW case.
340
341 void MasterFreeRegionListMtSafeChecker::check() {
342 // Master Free List MT safety protocol:
343 // (a) If we're at a safepoint, operations on the master free list
344 // should be invoked by either the VM thread (which will serialize
345 // them) or by the GC workers while holding the
346 // FreeList_lock.
347 // (b) If we're not at a safepoint, operations on the master free
348 // list should be invoked while holding the Heap_lock.
349
350 if (SafepointSynchronize::is_at_safepoint()) {
351 guarantee(Thread::current()->is_VM_thread() ||
352 FreeList_lock->owned_by_self(), "master free list MT safety protocol at a safepoint");
353 } else {
354 guarantee(Heap_lock->owned_by_self(), "master free list MT safety protocol outside a safepoint");
355 }
356 }
357
358 void SecondaryFreeRegionListMtSafeChecker::check() {
359 // Secondary Free List MT safety protocol:
360 // Operations on the secondary free list should always be invoked
361 // while holding the SecondaryFreeList_lock.
362
363 guarantee(SecondaryFreeList_lock->owned_by_self(), "secondary free list MT safety protocol");
364 }
365
366 void OldRegionSetMtSafeChecker::check() {
367 // Master Old Set MT safety protocol:
368 // (a) If we're at a safepoint, operations on the master old set
369 // should be invoked:
370 // - by the VM thread (which will serialize them), or
371 // - by the GC workers while holding the FreeList_lock, if we're
372 // at a safepoint for an evacuation pause (this lock is taken
373 // anyway when an GC alloc region is retired so that a new one
374 // is allocated from the free list), or
375 // - by the GC workers while holding the OldSets_lock, if we're at a
376 // safepoint for a cleanup pause.
377 // (b) If we're not at a safepoint, operations on the master old set
378 // should be invoked while holding the Heap_lock.
379
380 if (SafepointSynchronize::is_at_safepoint()) {
381 guarantee(Thread::current()->is_VM_thread()
382 || FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
383 "master old set MT safety protocol at a safepoint");
384 } else {
385 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
386 }
387 }
388
389 void HumongousRegionSetMtSafeChecker::check() {
390 // Humongous Set MT safety protocol:
391 // (a) If we're at a safepoint, operations on the master humongous
392 // set should be invoked by either the VM thread (which will
393 // serialize them) or by the GC workers while holding the
394 // OldSets_lock.
395 // (b) If we're not at a safepoint, operations on the master
396 // humongous set should be invoked while holding the Heap_lock.
397
398 if (SafepointSynchronize::is_at_safepoint()) {
399 guarantee(Thread::current()->is_VM_thread() ||
400 OldSets_lock->owned_by_self(),
401 "master humongous set MT safety protocol at a safepoint");
402 } else {
403 guarantee(Heap_lock->owned_by_self(),
404 "master humongous set MT safety protocol outside a safepoint");
405 }
406 }
407
408 void FreeRegionList_test() {
409 FreeRegionList l("test");
410
411 const uint num_regions_in_test = 5;
412 // Create a fake heap. It does not need to be valid, as the HeapRegion constructor
413 // does not access it.
414 MemRegion heap(NULL, num_regions_in_test * HeapRegion::GrainWords);
415 // Allocate a fake BOT because the HeapRegion constructor initializes
416 // the BOT.
417 size_t bot_size = G1BlockOffsetSharedArray::compute_size(heap.word_size());
418 HeapWord* bot_data = NEW_C_HEAP_ARRAY(HeapWord, bot_size, mtGC);
419 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(heap.word_size()));
420 G1RegionToSpaceMapper* bot_storage =
421 G1RegionToSpaceMapper::create_mapper(bot_rs,
422 os::vm_page_size(),
423 HeapRegion::GrainBytes,
424 G1BlockOffsetSharedArray::N_bytes,
425 mtGC);
426 G1BlockOffsetSharedArray oa(heap, bot_storage);
427 bot_storage->commit_regions(0, num_regions_in_test);
428
429 // Set up memory regions for the heap regions.
430 MemRegion mr0(heap.start(), HeapRegion::GrainWords);
431 MemRegion mr1(mr0.end(), HeapRegion::GrainWords);
432 MemRegion mr2(mr1.end(), HeapRegion::GrainWords);
433 MemRegion mr3(mr2.end(), HeapRegion::GrainWords);
434 MemRegion mr4(mr3.end(), HeapRegion::GrainWords);
435
436 HeapRegion hr0(0, &oa, mr0);
437 HeapRegion hr1(1, &oa, mr1);
438 HeapRegion hr2(2, &oa, mr2);
439 HeapRegion hr3(3, &oa, mr3);
440 HeapRegion hr4(4, &oa, mr4);
441 l.add_ordered(&hr1);
442 l.add_ordered(&hr0);
443 l.add_ordered(&hr3);
444 l.add_ordered(&hr4);
445 l.add_ordered(&hr2);
446 assert(l.length() == num_regions_in_test, "wrong length");
447 l.verify_list();
448
449 bot_storage->uncommit_regions(0, num_regions_in_test);
450 delete bot_storage;
451 FREE_C_HEAP_ARRAY(HeapWord, bot_data);
452 }