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/g1/g1CollectedHeap.inline.hpp"
27 #include "gc/g1/satbQueue.hpp"
28 #include "gc/shared/collectedHeap.hpp"
29 #include "memory/allocation.inline.hpp"
30 #include "oops/oop.inline.hpp"
31 #include "runtime/mutexLocker.hpp"
32 #include "runtime/safepoint.hpp"
33 #include "runtime/thread.hpp"
34 #include "runtime/vmThread.hpp"
35
36 void ObjPtrQueue::flush() {
37 // Filter now to possibly save work later. If filtering empties the
38 // buffer then flush_impl can deallocate the buffer.
39 filter();
40 flush_impl();
41 }
42
43 // Return true if a SATB buffer entry refers to an object that
44 // requires marking.
45 //
46 // The entry must point into the G1 heap. In particular, it must not
47 // be a NULL pointer. NULL pointers are pre-filtered and never
48 // inserted into a SATB buffer.
49 //
50 // An entry that is below the NTAMS pointer for the containing heap
51 // region requires marking. Such an entry must point to a valid object.
52 //
53 // An entry that is at least the NTAMS pointer for the containing heap
54 // region might be any of the following, none of which should be marked.
55 //
82 HeapRegion* region = heap->heap_region_containing_raw(entry);
83 assert(region != NULL, "No region for " PTR_FORMAT, p2i(entry));
84 if (entry >= region->next_top_at_mark_start()) {
85 return false;
86 }
87
88 assert(((oop)entry)->is_oop(true /* ignore mark word */),
89 "Invalid oop in SATB buffer: " PTR_FORMAT, p2i(entry));
90
91 return true;
92 }
93
94 // This method removes entries from a SATB buffer that will not be
95 // useful to the concurrent marking threads. Entries are retained if
96 // they require marking and are not already marked. Retained entries
97 // are compacted toward the top of the buffer.
98
99 void ObjPtrQueue::filter() {
100 G1CollectedHeap* g1h = G1CollectedHeap::heap();
101 void** buf = _buf;
102 size_t sz = _sz;
103
104 if (buf == NULL) {
105 // nothing to do
106 return;
107 }
108
109 // Used for sanity checking at the end of the loop.
110 debug_only(size_t entries = 0; size_t retained = 0;)
111
112 size_t i = sz;
113 size_t new_index = sz;
114
115 while (i > _index) {
116 assert(i > 0, "we should have at least one more entry to process");
117 i -= oopSize;
118 debug_only(entries += 1;)
119 void** p = &buf[byte_index_to_index((int) i)];
120 void* entry = *p;
121 // NULL the entry so that unused parts of the buffer contain NULLs
122 // at the end. If we are going to retain it we will copy it to its
123 // final place. If we have retained all entries we have visited so
124 // far, we'll just end up copying it to the same place.
125 *p = NULL;
126
127 if (requires_marking(entry, g1h) && !g1h->isMarkedNext((oop)entry)) {
128 assert(new_index > 0, "we should not have already filled up the buffer");
129 new_index -= oopSize;
130 assert(new_index >= i,
131 "new_index should never be below i, as we always compact 'up'");
132 void** new_p = &buf[byte_index_to_index((int) new_index)];
133 assert(new_p >= p, "the destination location should never be below "
134 "the source as we always compact 'up'");
135 assert(*new_p == NULL,
136 "we should have already cleared the destination location");
137 *new_p = entry;
138 debug_only(retained += 1;)
139 }
140 }
141
142 #ifdef ASSERT
143 size_t entries_calc = (sz - _index) / oopSize;
144 assert(entries == entries_calc, "the number of entries we counted "
145 "should match the number of entries we calculated");
146 size_t retained_calc = (sz - new_index) / oopSize;
147 assert(retained == retained_calc, "the number of retained entries we counted "
148 "should match the number of retained entries we calculated");
149 #endif // ASSERT
150
151 _index = new_index;
152 }
153
154 // This method will first apply the above filtering to the buffer. If
155 // post-filtering a large enough chunk of the buffer has been cleared
156 // we can re-use the buffer (instead of enqueueing it) and we can just
157 // allow the mutator to carry on executing using the same buffer
158 // instead of replacing it.
159
160 bool ObjPtrQueue::should_enqueue_buffer() {
161 assert(_lock == NULL || _lock->owned_by_self(),
162 "we should have taken the lock before calling this");
163
164 // If G1SATBBufferEnqueueingThresholdPercent == 0 we could skip filtering.
165
166 // This method should only be called if there is a non-NULL buffer
167 // that is full.
168 assert(_index == 0, "pre-condition");
169 assert(_buf != NULL, "pre-condition");
170
171 filter();
172
173 size_t sz = _sz;
174 size_t all_entries = sz / oopSize;
175 size_t retained_entries = (sz - _index) / oopSize;
176 size_t perc = retained_entries * 100 / all_entries;
177 bool should_enqueue = perc > (size_t) G1SATBBufferEnqueueingThresholdPercent;
178 return should_enqueue;
179 }
180
181 void ObjPtrQueue::apply_closure_and_empty(SATBBufferClosure* cl) {
182 assert(SafepointSynchronize::is_at_safepoint(),
183 "SATB queues must only be processed at safepoints");
184 if (_buf != NULL) {
185 assert(_index % sizeof(void*) == 0, "invariant");
186 assert(_sz % sizeof(void*) == 0, "invariant");
187 assert(_index <= _sz, "invariant");
188 cl->do_buffer(_buf + byte_index_to_index((int)_index),
189 byte_index_to_index((int)(_sz - _index)));
190 _index = _sz;
191 }
192 }
193
194 #ifndef PRODUCT
195 // Helpful for debugging
196
197 void ObjPtrQueue::print(const char* name) {
198 print(name, _buf, _index, _sz);
199 }
200
201 void ObjPtrQueue::print(const char* name,
202 void** buf, size_t index, size_t sz) {
203 gclog_or_tty->print_cr(" SATB BUFFER [%s] buf: " PTR_FORMAT " "
204 "index: " SIZE_FORMAT " sz: " SIZE_FORMAT,
205 name, p2i(buf), index, sz);
206 }
207 #endif // PRODUCT
208
209 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
282 }
283
284 bool SATBMarkQueueSet::apply_closure_to_completed_buffer(SATBBufferClosure* cl) {
285 BufferNode* nd = NULL;
286 {
287 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
288 if (_completed_buffers_head != NULL) {
289 nd = _completed_buffers_head;
290 _completed_buffers_head = nd->next();
291 if (_completed_buffers_head == NULL) _completed_buffers_tail = NULL;
292 _n_completed_buffers--;
293 if (_n_completed_buffers == 0) _process_completed = false;
294 }
295 }
296 if (nd != NULL) {
297 void **buf = BufferNode::make_buffer_from_node(nd);
298 // Skip over NULL entries at beginning (e.g. push end) of buffer.
299 // Filtering can result in non-full completed buffers; see
300 // should_enqueue_buffer.
301 assert(_sz % sizeof(void*) == 0, "invariant");
302 size_t limit = ObjPtrQueue::byte_index_to_index((int)_sz);
303 for (size_t i = 0; i < limit; ++i) {
304 if (buf[i] != NULL) {
305 // Found the end of the block of NULLs; process the remainder.
306 cl->do_buffer(buf + i, limit - i);
307 break;
308 }
309 }
310 deallocate_buffer(buf);
311 return true;
312 } else {
313 return false;
314 }
315 }
316
317 #ifndef PRODUCT
318 // Helpful for debugging
319
320 #define SATB_PRINTER_BUFFER_SIZE 256
321
322 void SATBMarkQueueSet::print_all(const char* msg) {
|
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/g1/g1CollectedHeap.inline.hpp"
27 #include "gc/g1/satbQueue.hpp"
28 #include "gc/shared/collectedHeap.hpp"
29 #include "memory/allocation.inline.hpp"
30 #include "oops/oop.inline.hpp"
31 #include "runtime/mutexLocker.hpp"
32 #include "runtime/safepoint.hpp"
33 #include "runtime/thread.hpp"
34 #include "runtime/vmThread.hpp"
35
36 ObjPtrQueue::ObjPtrQueue(SATBMarkQueueSet* qset, bool permanent) :
37 // SATB queues are only active during marking cycles. We create
38 // them with their active field set to false. If a thread is
39 // created during a cycle and its SATB queue needs to be activated
40 // before the thread starts running, we'll need to set its active
41 // field to true. This is done in JavaThread::initialize_queues().
42 PtrQueue(qset, permanent, false /* active */)
43 { }
44
45 void ObjPtrQueue::flush() {
46 // Filter now to possibly save work later. If filtering empties the
47 // buffer then flush_impl can deallocate the buffer.
48 filter();
49 flush_impl();
50 }
51
52 // Return true if a SATB buffer entry refers to an object that
53 // requires marking.
54 //
55 // The entry must point into the G1 heap. In particular, it must not
56 // be a NULL pointer. NULL pointers are pre-filtered and never
57 // inserted into a SATB buffer.
58 //
59 // An entry that is below the NTAMS pointer for the containing heap
60 // region requires marking. Such an entry must point to a valid object.
61 //
62 // An entry that is at least the NTAMS pointer for the containing heap
63 // region might be any of the following, none of which should be marked.
64 //
91 HeapRegion* region = heap->heap_region_containing_raw(entry);
92 assert(region != NULL, "No region for " PTR_FORMAT, p2i(entry));
93 if (entry >= region->next_top_at_mark_start()) {
94 return false;
95 }
96
97 assert(((oop)entry)->is_oop(true /* ignore mark word */),
98 "Invalid oop in SATB buffer: " PTR_FORMAT, p2i(entry));
99
100 return true;
101 }
102
103 // This method removes entries from a SATB buffer that will not be
104 // useful to the concurrent marking threads. Entries are retained if
105 // they require marking and are not already marked. Retained entries
106 // are compacted toward the top of the buffer.
107
108 void ObjPtrQueue::filter() {
109 G1CollectedHeap* g1h = G1CollectedHeap::heap();
110 void** buf = _buf;
111
112 if (buf == NULL) {
113 // nothing to do
114 return;
115 }
116
117 // Used for sanity checking at the end of the loop.
118 DEBUG_ONLY(size_t entries = 0; size_t retained = 0;)
119
120 assert(_index <= _sz, "invariant");
121 void** limit = &buf[byte_index_to_index(_index)];
122 void** src = &buf[byte_index_to_index(_sz)];
123 void** dst = src;
124
125 while (limit < src) {
126 DEBUG_ONLY(entries += 1;)
127 --src;
128 void* entry = *src;
129 // NULL the entry so that unused parts of the buffer contain NULLs
130 // at the end. If we are going to retain it we will copy it to its
131 // final place. If we have retained all entries we have visited so
132 // far, we'll just end up copying it to the same place.
133 *src = NULL;
134
135 if (requires_marking(entry, g1h) && !g1h->isMarkedNext((oop)entry)) {
136 --dst;
137 assert(*dst == NULL, "filtering destination should be clear");
138 *dst = entry;
139 DEBUG_ONLY(retained += 1;);
140 }
141 }
142 size_t new_index = pointer_delta(dst, buf, 1);
143
144 #ifdef ASSERT
145 size_t entries_calc = (_sz - _index) / sizeof(void*);
146 assert(entries == entries_calc, "the number of entries we counted "
147 "should match the number of entries we calculated");
148 size_t retained_calc = (_sz - new_index) / sizeof(void*);
149 assert(retained == retained_calc, "the number of retained entries we counted "
150 "should match the number of retained entries we calculated");
151 #endif // ASSERT
152
153 _index = new_index;
154 }
155
156 // This method will first apply the above filtering to the buffer. If
157 // post-filtering a large enough chunk of the buffer has been cleared
158 // we can re-use the buffer (instead of enqueueing it) and we can just
159 // allow the mutator to carry on executing using the same buffer
160 // instead of replacing it.
161
162 bool ObjPtrQueue::should_enqueue_buffer() {
163 assert(_lock == NULL || _lock->owned_by_self(),
164 "we should have taken the lock before calling this");
165
166 // If G1SATBBufferEnqueueingThresholdPercent == 0 we could skip filtering.
167
168 // This method should only be called if there is a non-NULL buffer
169 // that is full.
170 assert(_index == 0, "pre-condition");
171 assert(_buf != NULL, "pre-condition");
172
173 filter();
174
175 size_t sz = _sz;
176 size_t all_entries = sz / sizeof(void*);
177 size_t retained_entries = (sz - _index) / sizeof(void*);
178 size_t perc = retained_entries * 100 / all_entries;
179 bool should_enqueue = perc > (size_t) G1SATBBufferEnqueueingThresholdPercent;
180 return should_enqueue;
181 }
182
183 void ObjPtrQueue::apply_closure_and_empty(SATBBufferClosure* cl) {
184 assert(SafepointSynchronize::is_at_safepoint(),
185 "SATB queues must only be processed at safepoints");
186 if (_buf != NULL) {
187 assert(_index % sizeof(void*) == 0, "invariant");
188 assert(_sz % sizeof(void*) == 0, "invariant");
189 assert(_index <= _sz, "invariant");
190 cl->do_buffer(_buf + byte_index_to_index(_index),
191 byte_index_to_index(_sz - _index));
192 _index = _sz;
193 }
194 }
195
196 #ifndef PRODUCT
197 // Helpful for debugging
198
199 void ObjPtrQueue::print(const char* name) {
200 print(name, _buf, _index, _sz);
201 }
202
203 void ObjPtrQueue::print(const char* name,
204 void** buf, size_t index, size_t sz) {
205 gclog_or_tty->print_cr(" SATB BUFFER [%s] buf: " PTR_FORMAT " "
206 "index: " SIZE_FORMAT " sz: " SIZE_FORMAT,
207 name, p2i(buf), index, sz);
208 }
209 #endif // PRODUCT
210
211 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
284 }
285
286 bool SATBMarkQueueSet::apply_closure_to_completed_buffer(SATBBufferClosure* cl) {
287 BufferNode* nd = NULL;
288 {
289 MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
290 if (_completed_buffers_head != NULL) {
291 nd = _completed_buffers_head;
292 _completed_buffers_head = nd->next();
293 if (_completed_buffers_head == NULL) _completed_buffers_tail = NULL;
294 _n_completed_buffers--;
295 if (_n_completed_buffers == 0) _process_completed = false;
296 }
297 }
298 if (nd != NULL) {
299 void **buf = BufferNode::make_buffer_from_node(nd);
300 // Skip over NULL entries at beginning (e.g. push end) of buffer.
301 // Filtering can result in non-full completed buffers; see
302 // should_enqueue_buffer.
303 assert(_sz % sizeof(void*) == 0, "invariant");
304 size_t limit = ObjPtrQueue::byte_index_to_index(_sz);
305 for (size_t i = 0; i < limit; ++i) {
306 if (buf[i] != NULL) {
307 // Found the end of the block of NULLs; process the remainder.
308 cl->do_buffer(buf + i, limit - i);
309 break;
310 }
311 }
312 deallocate_buffer(buf);
313 return true;
314 } else {
315 return false;
316 }
317 }
318
319 #ifndef PRODUCT
320 // Helpful for debugging
321
322 #define SATB_PRINTER_BUFFER_SIZE 256
323
324 void SATBMarkQueueSet::print_all(const char* msg) {
|