1 /*
2 * Copyright (c) 2010, 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/concurrentMarkSweep/compactibleFreeListSpace.hpp"
27 #include "gc_implementation/concurrentMarkSweep/promotionInfo.hpp"
28 #include "oops/markOop.inline.hpp"
29 #include "oops/oop.inline.hpp"
30
31 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
32
33 /////////////////////////////////////////////////////////////////////////
34 //// PromotionInfo
35 /////////////////////////////////////////////////////////////////////////
36
37 void PromotionInfo::track(PromotedObject* trackOop) {
38 track(trackOop, oop(trackOop)->klass());
39 }
40
41 void PromotionInfo::track(PromotedObject* trackOop, Klass* klassOfOop) {
42 // make a copy of header as it may need to be spooled
43 markOop mark = oop(trackOop)->mark();
44 trackOop->clear_next();
45 if (mark->must_be_preserved_for_cms_scavenge(klassOfOop)) {
46 // save non-prototypical header, and mark oop
47 saveDisplacedHeader(mark);
48 trackOop->setDisplacedMark();
49 } else {
50 // we'd like to assert something like the following:
51 // assert(mark == markOopDesc::prototype(), "consistency check");
52 // ... but the above won't work because the age bits have not (yet) been
53 // cleared. The remainder of the check would be identical to the
54 // condition checked in must_be_preserved() above, so we don't really
55 // have anything useful to check here!
56 }
57 if (_promoTail != NULL) {
58 assert(_promoHead != NULL, "List consistency");
59 _promoTail->setNext(trackOop);
60 _promoTail = trackOop;
61 } else {
62 assert(_promoHead == NULL, "List consistency");
63 _promoHead = _promoTail = trackOop;
64 }
65 // Mask as newly promoted, so we can skip over such objects
66 // when scanning dirty cards
67 assert(!trackOop->hasPromotedMark(), "Should not have been marked");
68 trackOop->setPromotedMark();
69 }
70
71 // Save the given displaced header, incrementing the pointer and
72 // obtaining more spool area as necessary.
73 void PromotionInfo::saveDisplacedHeader(markOop hdr) {
74 assert(_spoolHead != NULL && _spoolTail != NULL,
75 "promotionInfo inconsistency");
76 assert(_spoolTail->bufferSize > _nextIndex, "Off by one error at tail?");
77 _spoolTail->displacedHdr[_nextIndex] = hdr;
78 // Spool forward
79 if (++_nextIndex == _spoolTail->bufferSize) { // last location in this block
80 // get a new spooling block
81 assert(_spoolTail->nextSpoolBlock == NULL, "tail should terminate spool list");
82 _splice_point = _spoolTail; // save for splicing
83 _spoolTail->nextSpoolBlock = getSpoolBlock(); // might fail
84 _spoolTail = _spoolTail->nextSpoolBlock; // might become NULL ...
85 // ... but will attempt filling before next promotion attempt
86 _nextIndex = 1;
87 }
88 }
89
90 // Ensure that spooling space exists. Return false if spooling space
91 // could not be obtained.
92 bool PromotionInfo::ensure_spooling_space_work() {
93 assert(!has_spooling_space(), "Only call when there is no spooling space");
94 // Try and obtain more spooling space
95 SpoolBlock* newSpool = getSpoolBlock();
96 assert(newSpool == NULL ||
97 (newSpool->bufferSize != 0 && newSpool->nextSpoolBlock == NULL),
98 "getSpoolBlock() sanity check");
99 if (newSpool == NULL) {
100 return false;
101 }
102 _nextIndex = 1;
103 if (_spoolTail == NULL) {
104 _spoolTail = newSpool;
105 if (_spoolHead == NULL) {
106 _spoolHead = newSpool;
107 _firstIndex = 1;
108 } else {
109 assert(_splice_point != NULL && _splice_point->nextSpoolBlock == NULL,
110 "Splice point invariant");
111 // Extra check that _splice_point is connected to list
112 #ifdef ASSERT
113 {
114 SpoolBlock* blk = _spoolHead;
115 for (; blk->nextSpoolBlock != NULL;
116 blk = blk->nextSpoolBlock);
117 assert(blk != NULL && blk == _splice_point,
118 "Splice point incorrect");
119 }
120 #endif // ASSERT
121 _splice_point->nextSpoolBlock = newSpool;
122 }
123 } else {
124 assert(_spoolHead != NULL, "spool list consistency");
125 _spoolTail->nextSpoolBlock = newSpool;
126 _spoolTail = newSpool;
127 }
128 return true;
129 }
130
131 // Get a free spool buffer from the free pool, getting a new block
132 // from the heap if necessary.
133 SpoolBlock* PromotionInfo::getSpoolBlock() {
134 SpoolBlock* res;
135 if ((res = _spareSpool) != NULL) {
136 _spareSpool = _spareSpool->nextSpoolBlock;
137 res->nextSpoolBlock = NULL;
138 } else { // spare spool exhausted, get some from heap
139 res = (SpoolBlock*)(space()->allocateScratch(refillSize()));
140 if (res != NULL) {
141 res->init();
142 }
143 }
144 assert(res == NULL || res->nextSpoolBlock == NULL, "postcondition");
145 return res;
146 }
147
148 void PromotionInfo::startTrackingPromotions() {
149 assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex,
150 "spooling inconsistency?");
151 _firstIndex = _nextIndex = 1;
152 _tracking = true;
153 }
154
155 #define CMSPrintPromoBlockInfo 1
156
157 void PromotionInfo::stopTrackingPromotions(uint worker_id) {
158 assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex,
159 "spooling inconsistency?");
160 _firstIndex = _nextIndex = 1;
161 _tracking = false;
162 if (CMSPrintPromoBlockInfo > 1) {
163 print_statistics(worker_id);
164 }
165 }
166
167 void PromotionInfo::print_statistics(uint worker_id) const {
168 assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex,
169 "Else will undercount");
170 assert(CMSPrintPromoBlockInfo > 0, "Else unnecessary call");
171 // Count the number of blocks and slots in the free pool
172 size_t slots = 0;
173 size_t blocks = 0;
174 for (SpoolBlock* cur_spool = _spareSpool;
175 cur_spool != NULL;
176 cur_spool = cur_spool->nextSpoolBlock) {
177 // the first entry is just a self-pointer; indices 1 through
178 // bufferSize - 1 are occupied (thus, bufferSize - 1 slots).
179 assert((void*)cur_spool->displacedHdr == (void*)&cur_spool->displacedHdr,
180 "first entry of displacedHdr should be self-referential");
181 slots += cur_spool->bufferSize - 1;
182 blocks++;
183 }
184 if (_spoolHead != NULL) {
185 slots += _spoolHead->bufferSize - 1;
186 blocks++;
187 }
188 gclog_or_tty->print_cr(" [worker %d] promo_blocks = " SIZE_FORMAT ", promo_slots = " SIZE_FORMAT,
189 worker_id, blocks, slots);
190 }
191
192 // When _spoolTail is not NULL, then the slot <_spoolTail, _nextIndex>
193 // points to the next slot available for filling.
194 // The set of slots holding displaced headers are then all those in the
195 // right-open interval denoted by:
196 //
197 // [ <_spoolHead, _firstIndex>, <_spoolTail, _nextIndex> )
198 //
199 // When _spoolTail is NULL, then the set of slots with displaced headers
200 // is all those starting at the slot <_spoolHead, _firstIndex> and
201 // going up to the last slot of last block in the linked list.
202 // In this latter case, _splice_point points to the tail block of
203 // this linked list of blocks holding displaced headers.
204 void PromotionInfo::verify() const {
205 // Verify the following:
206 // 1. the number of displaced headers matches the number of promoted
207 // objects that have displaced headers
208 // 2. each promoted object lies in this space
209 debug_only(
210 PromotedObject* junk = NULL;
211 assert(junk->next_addr() == (void*)(oop(junk)->mark_addr()),
212 "Offset of PromotedObject::_next is expected to align with "
213 " the OopDesc::_mark within OopDesc");
214 )
215 // FIXME: guarantee????
216 guarantee(_spoolHead == NULL || _spoolTail != NULL ||
217 _splice_point != NULL, "list consistency");
218 guarantee(_promoHead == NULL || _promoTail != NULL, "list consistency");
219 // count the number of objects with displaced headers
220 size_t numObjsWithDisplacedHdrs = 0;
221 for (PromotedObject* curObj = _promoHead; curObj != NULL; curObj = curObj->next()) {
222 guarantee(space()->is_in_reserved((HeapWord*)curObj), "Containment");
223 // the last promoted object may fail the mark() != NULL test of is_oop().
224 guarantee(curObj->next() == NULL || oop(curObj)->is_oop(), "must be an oop");
225 if (curObj->hasDisplacedMark()) {
226 numObjsWithDisplacedHdrs++;
227 }
228 }
229 // Count the number of displaced headers
230 size_t numDisplacedHdrs = 0;
231 for (SpoolBlock* curSpool = _spoolHead;
232 curSpool != _spoolTail && curSpool != NULL;
233 curSpool = curSpool->nextSpoolBlock) {
234 // the first entry is just a self-pointer; indices 1 through
235 // bufferSize - 1 are occupied (thus, bufferSize - 1 slots).
236 guarantee((void*)curSpool->displacedHdr == (void*)&curSpool->displacedHdr,
237 "first entry of displacedHdr should be self-referential");
238 numDisplacedHdrs += curSpool->bufferSize - 1;
239 }
240 guarantee((_spoolHead == _spoolTail) == (numDisplacedHdrs == 0),
241 "internal consistency");
242 guarantee(_spoolTail != NULL || _nextIndex == 1,
243 "Inconsistency between _spoolTail and _nextIndex");
244 // We overcounted (_firstIndex-1) worth of slots in block
245 // _spoolHead and we undercounted (_nextIndex-1) worth of
246 // slots in block _spoolTail. We make an appropriate
247 // adjustment by subtracting the first and adding the
248 // second: - (_firstIndex - 1) + (_nextIndex - 1)
249 numDisplacedHdrs += (_nextIndex - _firstIndex);
250 guarantee(numDisplacedHdrs == numObjsWithDisplacedHdrs, "Displaced hdr count");
251 }
252
253 void PromotionInfo::print_on(outputStream* st) const {
254 SpoolBlock* curSpool = NULL;
255 size_t i = 0;
256 st->print_cr(" start & end indices: [" SIZE_FORMAT ", " SIZE_FORMAT ")",
257 _firstIndex, _nextIndex);
258 for (curSpool = _spoolHead; curSpool != _spoolTail && curSpool != NULL;
259 curSpool = curSpool->nextSpoolBlock) {
260 curSpool->print_on(st);
261 st->print_cr(" active ");
262 i++;
263 }
264 for (curSpool = _spoolTail; curSpool != NULL;
265 curSpool = curSpool->nextSpoolBlock) {
266 curSpool->print_on(st);
267 st->print_cr(" inactive ");
268 i++;
269 }
270 for (curSpool = _spareSpool; curSpool != NULL;
271 curSpool = curSpool->nextSpoolBlock) {
272 curSpool->print_on(st);
273 st->print_cr(" free ");
274 i++;
275 }
276 st->print_cr(" " SIZE_FORMAT " header spooling blocks", i);
277 }
278
279 void SpoolBlock::print_on(outputStream* st) const {
280 st->print("[" PTR_FORMAT "," PTR_FORMAT "), " SIZE_FORMAT " HeapWords -> " PTR_FORMAT,
281 this, (HeapWord*)displacedHdr + bufferSize,
282 bufferSize, nextSpoolBlock);
283 }