1 /*
2 * Copyright (c) 2001, 2014, 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/satbQueue.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "memory/sharedHeap.hpp"
30 #include "oops/oop.inline.hpp"
31 #include "runtime/mutexLocker.hpp"
32 #include "runtime/thread.hpp"
33 #include "runtime/vmThread.hpp"
34
35 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
36
37 void ObjPtrQueue::flush() {
38 // The buffer might contain refs into the CSet. We have to filter it
39 // first before we flush it, otherwise we might end up with an
40 // enqueued buffer with refs into the CSet which breaks our invariants.
41 filter();
42 flush_impl();
43 }
44
45 // This method removes entries from an SATB buffer that will not be
46 // useful to the concurrent marking threads. An entry is removed if it
47 // satisfies one of the following conditions:
48 //
49 // * it points to an object outside the G1 heap (G1's concurrent
50 // marking only visits objects inside the G1 heap),
51 // * it points to an object that has been allocated since marking
52 // started (according to SATB those objects do not need to be
53 // visited during marking), or
54 // * it points to an object that has already been marked (no need to
55 // process it again).
56 //
57 // The rest of the entries will be retained and are compacted towards
58 // the top of the buffer. Note that, because we do not allow old
59 // regions in the CSet during marking, all objects on the CSet regions
60 // are young (eden or survivors) and therefore implicitly live. So any
61 // references into the CSet will be removed during filtering.
62
63 void ObjPtrQueue::filter() {
64 G1CollectedHeap* g1h = G1CollectedHeap::heap();
65 void** buf = _buf;
66 size_t sz = _sz;
67
68 if (buf == NULL) {
69 // nothing to do
70 return;
71 }
72
73 // Used for sanity checking at the end of the loop.
74 debug_only(size_t entries = 0; size_t retained = 0;)
75
76 size_t i = sz;
77 size_t new_index = sz;
78
79 while (i > _index) {
80 assert(i > 0, "we should have at least one more entry to process");
81 i -= oopSize;
82 debug_only(entries += 1;)
83 oop* p = (oop*) &buf[byte_index_to_index((int) i)];
84 oop obj = *p;
85 // NULL the entry so that unused parts of the buffer contain NULLs
86 // at the end. If we are going to retain it we will copy it to its
87 // final place. If we have retained all entries we have visited so
88 // far, we'll just end up copying it to the same place.
89 *p = NULL;
90
91 bool retain = g1h->is_obj_ill(obj);
92 if (retain) {
93 assert(new_index > 0, "we should not have already filled up the buffer");
94 new_index -= oopSize;
95 assert(new_index >= i,
96 "new_index should never be below i, as we alwaysr compact 'up'");
97 oop* new_p = (oop*) &buf[byte_index_to_index((int) new_index)];
98 assert(new_p >= p, "the destination location should never be below "
99 "the source as we always compact 'up'");
100 assert(*new_p == NULL,
101 "we should have already cleared the destination location");
102 *new_p = obj;
103 debug_only(retained += 1;)
104 }
105 }
106
107 #ifdef ASSERT
108 size_t entries_calc = (sz - _index) / oopSize;
109 assert(entries == entries_calc, "the number of entries we counted "
110 "should match the number of entries we calculated");
111 size_t retained_calc = (sz - new_index) / oopSize;
112 assert(retained == retained_calc, "the number of retained entries we counted "
113 "should match the number of retained entries we calculated");
114 #endif // ASSERT
115
116 _index = new_index;
117 }
118
119 // This method will first apply the above filtering to the buffer. If
120 // post-filtering a large enough chunk of the buffer has been cleared
121 // we can re-use the buffer (instead of enqueueing it) and we can just
122 // allow the mutator to carry on executing using the same buffer
169 cl->do_object(obj);
170 }
171 }
172 }
173
174 #ifndef PRODUCT
175 // Helpful for debugging
176
177 void ObjPtrQueue::print(const char* name) {
178 print(name, _buf, _index, _sz);
179 }
180
181 void ObjPtrQueue::print(const char* name,
182 void** buf, size_t index, size_t sz) {
183 gclog_or_tty->print_cr(" SATB BUFFER [%s] buf: "PTR_FORMAT" "
184 "index: "SIZE_FORMAT" sz: "SIZE_FORMAT,
185 name, buf, index, sz);
186 }
187 #endif // PRODUCT
188
189 #ifdef ASSERT
190 void ObjPtrQueue::verify_oops_in_buffer() {
191 if (_buf == NULL) return;
192 for (size_t i = _index; i < _sz; i += oopSize) {
193 oop obj = (oop)_buf[byte_index_to_index((int)i)];
194 assert(obj != NULL && obj->is_oop(true /* ignore mark word */),
195 "Not an oop");
196 }
197 }
198 #endif
199
200 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
201 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
202 #endif // _MSC_VER
203
204 SATBMarkQueueSet::SATBMarkQueueSet() :
205 PtrQueueSet(), _closure(NULL), _par_closures(NULL),
206 _shared_satb_queue(this, true /*perm*/) { }
207
208 void SATBMarkQueueSet::initialize(Monitor* cbl_mon, Mutex* fl_lock,
209 int process_completed_threshold,
210 Mutex* lock) {
211 PtrQueueSet::initialize(cbl_mon, fl_lock, process_completed_threshold, -1);
212 _shared_satb_queue.set_lock(lock);
213 if (ParallelGCThreads > 0) {
214 _par_closures = NEW_C_HEAP_ARRAY(ObjectClosure*, ParallelGCThreads, mtGC);
215 }
216 }
217
218 void SATBMarkQueueSet::handle_zero_index_for_thread(JavaThread* t) {
219 DEBUG_ONLY(t->satb_mark_queue().verify_oops_in_buffer();)
220 t->satb_mark_queue().handle_zero_index();
221 }
222
223 #ifdef ASSERT
224 void SATBMarkQueueSet::dump_active_states(bool expected_active) {
225 gclog_or_tty->print_cr("Expected SATB active state: %s",
226 expected_active ? "ACTIVE" : "INACTIVE");
227 gclog_or_tty->print_cr("Actual SATB active states:");
228 gclog_or_tty->print_cr(" Queue set: %s", is_active() ? "ACTIVE" : "INACTIVE");
229 for (JavaThread* t = Threads::first(); t; t = t->next()) {
230 gclog_or_tty->print_cr(" Thread \"%s\" queue: %s", t->name(),
231 t->satb_mark_queue().is_active() ? "ACTIVE" : "INACTIVE");
232 }
233 gclog_or_tty->print_cr(" Shared queue: %s",
234 shared_satb_queue()->is_active() ? "ACTIVE" : "INACTIVE");
235 }
236
237 void SATBMarkQueueSet::verify_active_states(bool expected_active) {
238 // Verify queue set state
239 if (is_active() != expected_active) {
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1 /*
2 * Copyright (c) 2001, 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/satbQueue.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "memory/sharedHeap.hpp"
30 #include "oops/oop.inline.hpp"
31 #include "runtime/mutexLocker.hpp"
32 #include "runtime/thread.hpp"
33 #include "runtime/vmThread.hpp"
34
35 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
36
37 void ObjPtrQueue::flush() {
38 // Filter now to possibly save work later. If filtering empties the
39 // buffer then flush_impl can deallocate the buffer.
40 filter();
41 flush_impl();
42 }
43
44 // Return true if a SATB buffer entry refers to an object that
45 // requires marking.
46 //
47 // The entry must point into the G1 heap. In particular, it must not
48 // be a NULL pointer. NULL pointers are pre-filtered and never
49 // inserted into a SATB buffer.
50 //
51 // An entry that is below the NTAMS pointer for the containing heap
52 // region requires marking. Such an entry must point to a valid object.
53 //
54 // An entry that is at least the NTAMS pointer for the containing heap
55 // region might be any of the following, none of which should be marked.
56 //
57 // * A reference to an object allocated since marking started.
58 // According to SATB, such objects are implicitly kept live and do
59 // not need to be dealt with via SATB buffer processing.
60 //
61 // * A reference to a young generation object. Young objects are
62 // handled separately and are not marked by concurrent marking.
63 //
64 // * A stale reference to a young generation object. If a young
65 // generation object reference is recorded and not filtered out
66 // before being moved by a young collection, the reference becomes
67 // stale.
68 //
69 // * A stale reference to an eagerly reclaimed humongous object. If a
70 // humongous object is recorded and then reclaimed, the reference
71 // becomes stale.
72 //
73 // The stale reference cases are implicitly handled by the NTAMS
74 // comparison. Because of the possibility of stale references, buffer
75 // processing must be somewhat circumspect and not assume entries
76 // in an unfiltered buffer refer to valid objects.
77
78 inline bool requires_marking(const void* entry, G1CollectedHeap* heap) {
79 // Includes rejection of NULL pointers.
80 assert(heap->is_in_reserved(entry),
81 err_msg("Non-heap pointer in SATB buffer: " PTR_FORMAT, p2i(entry)));
82
83 HeapRegion* region = heap->heap_region_containing_raw(entry);
84 assert(region != NULL, err_msg("No region for " PTR_FORMAT, p2i(entry)));
85 if (entry >= region->next_top_at_mark_start()) {
86 return false;
87 }
88
89 assert(((oop)entry)->is_oop(true /* ignore mark word */),
90 err_msg("Invalid oop in SATB buffer: " PTR_FORMAT, p2i(entry)));
91
92 return true;
93 }
94
95 // This method removes entries from a SATB buffer that will not be
96 // useful to the concurrent marking threads. Entries are retained if
97 // they require marking and are not already marked. Retained entries
98 // are compacted toward the top of the buffer.
99
100 void ObjPtrQueue::filter() {
101 G1CollectedHeap* g1h = G1CollectedHeap::heap();
102 void** buf = _buf;
103 size_t sz = _sz;
104
105 if (buf == NULL) {
106 // nothing to do
107 return;
108 }
109
110 // Used for sanity checking at the end of the loop.
111 debug_only(size_t entries = 0; size_t retained = 0;)
112
113 size_t i = sz;
114 size_t new_index = sz;
115
116 while (i > _index) {
117 assert(i > 0, "we should have at least one more entry to process");
118 i -= oopSize;
119 debug_only(entries += 1;)
120 void** p = &buf[byte_index_to_index((int) i)];
121 void* entry = *p;
122 // NULL the entry so that unused parts of the buffer contain NULLs
123 // at the end. If we are going to retain it we will copy it to its
124 // final place. If we have retained all entries we have visited so
125 // far, we'll just end up copying it to the same place.
126 *p = NULL;
127
128 if (requires_marking(entry, g1h) && !g1h->isMarkedNext((oop)entry)) {
129 assert(new_index > 0, "we should not have already filled up the buffer");
130 new_index -= oopSize;
131 assert(new_index >= i,
132 "new_index should never be below i, as we alwaysr compact 'up'");
133 void** new_p = &buf[byte_index_to_index((int) new_index)];
134 assert(new_p >= p, "the destination location should never be below "
135 "the source as we always compact 'up'");
136 assert(*new_p == NULL,
137 "we should have already cleared the destination location");
138 *new_p = entry;
139 debug_only(retained += 1;)
140 }
141 }
142
143 #ifdef ASSERT
144 size_t entries_calc = (sz - _index) / oopSize;
145 assert(entries == entries_calc, "the number of entries we counted "
146 "should match the number of entries we calculated");
147 size_t retained_calc = (sz - new_index) / oopSize;
148 assert(retained == retained_calc, "the number of retained entries we counted "
149 "should match the number of retained entries we calculated");
150 #endif // ASSERT
151
152 _index = new_index;
153 }
154
155 // This method will first apply the above filtering to the buffer. If
156 // post-filtering a large enough chunk of the buffer has been cleared
157 // we can re-use the buffer (instead of enqueueing it) and we can just
158 // allow the mutator to carry on executing using the same buffer
205 cl->do_object(obj);
206 }
207 }
208 }
209
210 #ifndef PRODUCT
211 // Helpful for debugging
212
213 void ObjPtrQueue::print(const char* name) {
214 print(name, _buf, _index, _sz);
215 }
216
217 void ObjPtrQueue::print(const char* name,
218 void** buf, size_t index, size_t sz) {
219 gclog_or_tty->print_cr(" SATB BUFFER [%s] buf: "PTR_FORMAT" "
220 "index: "SIZE_FORMAT" sz: "SIZE_FORMAT,
221 name, buf, index, sz);
222 }
223 #endif // PRODUCT
224
225 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
226 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
227 #endif // _MSC_VER
228
229 SATBMarkQueueSet::SATBMarkQueueSet() :
230 PtrQueueSet(), _closure(NULL), _par_closures(NULL),
231 _shared_satb_queue(this, true /*perm*/) { }
232
233 void SATBMarkQueueSet::initialize(Monitor* cbl_mon, Mutex* fl_lock,
234 int process_completed_threshold,
235 Mutex* lock) {
236 PtrQueueSet::initialize(cbl_mon, fl_lock, process_completed_threshold, -1);
237 _shared_satb_queue.set_lock(lock);
238 if (ParallelGCThreads > 0) {
239 _par_closures = NEW_C_HEAP_ARRAY(ObjectClosure*, ParallelGCThreads, mtGC);
240 }
241 }
242
243 void SATBMarkQueueSet::handle_zero_index_for_thread(JavaThread* t) {
244 t->satb_mark_queue().handle_zero_index();
245 }
246
247 #ifdef ASSERT
248 void SATBMarkQueueSet::dump_active_states(bool expected_active) {
249 gclog_or_tty->print_cr("Expected SATB active state: %s",
250 expected_active ? "ACTIVE" : "INACTIVE");
251 gclog_or_tty->print_cr("Actual SATB active states:");
252 gclog_or_tty->print_cr(" Queue set: %s", is_active() ? "ACTIVE" : "INACTIVE");
253 for (JavaThread* t = Threads::first(); t; t = t->next()) {
254 gclog_or_tty->print_cr(" Thread \"%s\" queue: %s", t->name(),
255 t->satb_mark_queue().is_active() ? "ACTIVE" : "INACTIVE");
256 }
257 gclog_or_tty->print_cr(" Shared queue: %s",
258 shared_satb_queue()->is_active() ? "ACTIVE" : "INACTIVE");
259 }
260
261 void SATBMarkQueueSet::verify_active_states(bool expected_active) {
262 // Verify queue set state
263 if (is_active() != expected_active) {
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