1 /*
2 * Copyright (c) 2010, 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.
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23 */
24
25 # include "incls/_precompiled.incl"
26 # include "incls/_promotionInfo.cpp.incl"
27
28 /////////////////////////////////////////////////////////////////////////
29 //// PromotionInfo
30 /////////////////////////////////////////////////////////////////////////
31
32
33 //////////////////////////////////////////////////////////////////////////////
34 // We go over the list of promoted objects, removing each from the list,
35 // and applying the closure (this may, in turn, add more elements to
36 // the tail of the promoted list, and these newly added objects will
37 // also be processed) until the list is empty.
38 // To aid verification and debugging, in the non-product builds
39 // we actually forward _promoHead each time we process a promoted oop.
40 // Note that this is not necessary in general (i.e. when we don't need to
41 // call PromotionInfo::verify()) because oop_iterate can only add to the
42 // end of _promoTail, and never needs to look at _promoHead.
43
44 #define PROMOTED_OOPS_ITERATE_DEFN(OopClosureType, nv_suffix) \
45 \
46 void PromotionInfo::promoted_oops_iterate##nv_suffix(OopClosureType* cl) { \
47 NOT_PRODUCT(verify()); \
48 PromotedObject *curObj, *nextObj; \
49 for (curObj = _promoHead; curObj != NULL; curObj = nextObj) { \
50 if ((nextObj = curObj->next()) == NULL) { \
51 /* protect ourselves against additions due to closure application \
52 below by resetting the list. */ \
53 assert(_promoTail == curObj, "Should have been the tail"); \
54 _promoHead = _promoTail = NULL; \
55 } \
56 if (curObj->hasDisplacedMark()) { \
57 /* restore displaced header */ \
58 oop(curObj)->set_mark(nextDisplacedHeader()); \
59 } else { \
60 /* restore prototypical header */ \
61 oop(curObj)->init_mark(); \
62 } \
63 /* The "promoted_mark" should now not be set */ \
64 assert(!curObj->hasPromotedMark(), \
65 "Should have been cleared by restoring displaced mark-word"); \
66 NOT_PRODUCT(_promoHead = nextObj); \
67 if (cl != NULL) oop(curObj)->oop_iterate(cl); \
68 if (nextObj == NULL) { /* start at head of list reset above */ \
69 nextObj = _promoHead; \
70 } \
71 } \
72 assert(noPromotions(), "post-condition violation"); \
73 assert(_promoHead == NULL && _promoTail == NULL, "emptied promoted list");\
74 assert(_spoolHead == _spoolTail, "emptied spooling buffers"); \
75 assert(_firstIndex == _nextIndex, "empty buffer"); \
76 }
77
78 // This should have been ALL_SINCE_...() just like the others,
79 // but, because the body of the method above is somehwat longer,
80 // the MSVC compiler cannot cope; as a workaround, we split the
81 // macro into its 3 constituent parts below (see original macro
82 // definition in specializedOopClosures.hpp).
83 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES_YOUNG(PROMOTED_OOPS_ITERATE_DEFN)
84 PROMOTED_OOPS_ITERATE_DEFN(OopsInGenClosure,_v)
85
86
87 // Return the next displaced header, incrementing the pointer and
88 // recycling spool area as necessary.
89 markOop PromotionInfo::nextDisplacedHeader() {
90 assert(_spoolHead != NULL, "promotionInfo inconsistency");
91 assert(_spoolHead != _spoolTail || _firstIndex < _nextIndex,
92 "Empty spool space: no displaced header can be fetched");
93 assert(_spoolHead->bufferSize > _firstIndex, "Off by one error at head?");
94 markOop hdr = _spoolHead->displacedHdr[_firstIndex];
95 // Spool forward
96 if (++_firstIndex == _spoolHead->bufferSize) { // last location in this block
97 // forward to next block, recycling this block into spare spool buffer
98 SpoolBlock* tmp = _spoolHead->nextSpoolBlock;
99 assert(_spoolHead != _spoolTail, "Spooling storage mix-up");
100 _spoolHead->nextSpoolBlock = _spareSpool;
101 _spareSpool = _spoolHead;
102 _spoolHead = tmp;
103 _firstIndex = 1;
104 NOT_PRODUCT(
105 if (_spoolHead == NULL) { // all buffers fully consumed
106 assert(_spoolTail == NULL && _nextIndex == 1,
107 "spool buffers processing inconsistency");
108 }
109 )
110 }
111 return hdr;
112 }
113
114 void PromotionInfo::track(PromotedObject* trackOop) {
115 track(trackOop, oop(trackOop)->klass());
116 }
117
118 void PromotionInfo::track(PromotedObject* trackOop, klassOop klassOfOop) {
119 // make a copy of header as it may need to be spooled
120 markOop mark = oop(trackOop)->mark();
121 trackOop->clearNext();
122 if (mark->must_be_preserved_for_cms_scavenge(klassOfOop)) {
123 // save non-prototypical header, and mark oop
124 saveDisplacedHeader(mark);
125 trackOop->setDisplacedMark();
126 } else {
127 // we'd like to assert something like the following:
128 // assert(mark == markOopDesc::prototype(), "consistency check");
129 // ... but the above won't work because the age bits have not (yet) been
130 // cleared. The remainder of the check would be identical to the
131 // condition checked in must_be_preserved() above, so we don't really
132 // have anything useful to check here!
133 }
134 if (_promoTail != NULL) {
135 assert(_promoHead != NULL, "List consistency");
136 _promoTail->setNext(trackOop);
137 _promoTail = trackOop;
138 } else {
139 assert(_promoHead == NULL, "List consistency");
140 _promoHead = _promoTail = trackOop;
141 }
142 // Mask as newly promoted, so we can skip over such objects
143 // when scanning dirty cards
144 assert(!trackOop->hasPromotedMark(), "Should not have been marked");
145 trackOop->setPromotedMark();
146 }
147
148 // Save the given displaced header, incrementing the pointer and
149 // obtaining more spool area as necessary.
150 void PromotionInfo::saveDisplacedHeader(markOop hdr) {
151 assert(_spoolHead != NULL && _spoolTail != NULL,
152 "promotionInfo inconsistency");
153 assert(_spoolTail->bufferSize > _nextIndex, "Off by one error at tail?");
154 _spoolTail->displacedHdr[_nextIndex] = hdr;
155 // Spool forward
156 if (++_nextIndex == _spoolTail->bufferSize) { // last location in this block
157 // get a new spooling block
158 assert(_spoolTail->nextSpoolBlock == NULL, "tail should terminate spool list");
159 _splice_point = _spoolTail; // save for splicing
160 _spoolTail->nextSpoolBlock = getSpoolBlock(); // might fail
161 _spoolTail = _spoolTail->nextSpoolBlock; // might become NULL ...
162 // ... but will attempt filling before next promotion attempt
163 _nextIndex = 1;
164 }
165 }
166
167 // Ensure that spooling space exists. Return false if spooling space
168 // could not be obtained.
169 bool PromotionInfo::ensure_spooling_space_work() {
170 assert(!has_spooling_space(), "Only call when there is no spooling space");
171 // Try and obtain more spooling space
172 SpoolBlock* newSpool = getSpoolBlock();
173 assert(newSpool == NULL ||
174 (newSpool->bufferSize != 0 && newSpool->nextSpoolBlock == NULL),
175 "getSpoolBlock() sanity check");
176 if (newSpool == NULL) {
177 return false;
178 }
179 _nextIndex = 1;
180 if (_spoolTail == NULL) {
181 _spoolTail = newSpool;
182 if (_spoolHead == NULL) {
183 _spoolHead = newSpool;
184 _firstIndex = 1;
185 } else {
186 assert(_splice_point != NULL && _splice_point->nextSpoolBlock == NULL,
187 "Splice point invariant");
188 // Extra check that _splice_point is connected to list
189 #ifdef ASSERT
190 {
191 SpoolBlock* blk = _spoolHead;
192 for (; blk->nextSpoolBlock != NULL;
193 blk = blk->nextSpoolBlock);
194 assert(blk != NULL && blk == _splice_point,
195 "Splice point incorrect");
196 }
197 #endif // ASSERT
198 _splice_point->nextSpoolBlock = newSpool;
199 }
200 } else {
201 assert(_spoolHead != NULL, "spool list consistency");
202 _spoolTail->nextSpoolBlock = newSpool;
203 _spoolTail = newSpool;
204 }
205 return true;
206 }
207
208 // Get a free spool buffer from the free pool, getting a new block
209 // from the heap if necessary.
210 SpoolBlock* PromotionInfo::getSpoolBlock() {
211 SpoolBlock* res;
212 if ((res = _spareSpool) != NULL) {
213 _spareSpool = _spareSpool->nextSpoolBlock;
214 res->nextSpoolBlock = NULL;
215 } else { // spare spool exhausted, get some from heap
216 res = (SpoolBlock*)(space()->allocateScratch(refillSize()));
217 if (res != NULL) {
218 res->init();
219 }
220 }
221 assert(res == NULL || res->nextSpoolBlock == NULL, "postcondition");
222 return res;
223 }
224
225 void PromotionInfo::startTrackingPromotions() {
226 assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex,
227 "spooling inconsistency?");
228 _firstIndex = _nextIndex = 1;
229 _tracking = true;
230 }
231
232 #define CMSPrintPromoBlockInfo 1
233
234 void PromotionInfo::stopTrackingPromotions(uint worker_id) {
235 assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex,
236 "spooling inconsistency?");
237 _firstIndex = _nextIndex = 1;
238 _tracking = false;
239 if (CMSPrintPromoBlockInfo > 1) {
240 print_statistics(worker_id);
241 }
242 }
243
244 void PromotionInfo::print_statistics(uint worker_id) const {
245 assert(_spoolHead == _spoolTail && _firstIndex == _nextIndex,
246 "Else will undercount");
247 assert(CMSPrintPromoBlockInfo > 0, "Else unnecessary call");
248 // Count the number of blocks and slots in the free pool
249 size_t slots = 0;
250 size_t blocks = 0;
251 for (SpoolBlock* cur_spool = _spareSpool;
252 cur_spool != NULL;
253 cur_spool = cur_spool->nextSpoolBlock) {
254 // the first entry is just a self-pointer; indices 1 through
255 // bufferSize - 1 are occupied (thus, bufferSize - 1 slots).
256 assert((void*)cur_spool->displacedHdr == (void*)&cur_spool->displacedHdr,
257 "first entry of displacedHdr should be self-referential");
258 slots += cur_spool->bufferSize - 1;
259 blocks++;
260 }
261 if (_spoolHead != NULL) {
262 slots += _spoolHead->bufferSize - 1;
263 blocks++;
264 }
265 gclog_or_tty->print_cr(" [worker %d] promo_blocks = %d, promo_slots = %d ",
266 worker_id, blocks, slots);
267 }
268
269 // When _spoolTail is not NULL, then the slot <_spoolTail, _nextIndex>
270 // points to the next slot available for filling.
271 // The set of slots holding displaced headers are then all those in the
272 // right-open interval denoted by:
273 //
274 // [ <_spoolHead, _firstIndex>, <_spoolTail, _nextIndex> )
275 //
276 // When _spoolTail is NULL, then the set of slots with displaced headers
277 // is all those starting at the slot <_spoolHead, _firstIndex> and
278 // going up to the last slot of last block in the linked list.
279 // In this lartter case, _splice_point points to the tail block of
280 // this linked list of blocks holding displaced headers.
281 void PromotionInfo::verify() const {
282 // Verify the following:
283 // 1. the number of displaced headers matches the number of promoted
284 // objects that have displaced headers
285 // 2. each promoted object lies in this space
286 debug_only(
287 PromotedObject* junk = NULL;
288 assert(junk->next_addr() == (void*)(oop(junk)->mark_addr()),
289 "Offset of PromotedObject::_next is expected to align with "
290 " the OopDesc::_mark within OopDesc");
291 )
292 // FIXME: guarantee????
293 guarantee(_spoolHead == NULL || _spoolTail != NULL ||
294 _splice_point != NULL, "list consistency");
295 guarantee(_promoHead == NULL || _promoTail != NULL, "list consistency");
296 // count the number of objects with displaced headers
297 size_t numObjsWithDisplacedHdrs = 0;
298 for (PromotedObject* curObj = _promoHead; curObj != NULL; curObj = curObj->next()) {
299 guarantee(space()->is_in_reserved((HeapWord*)curObj), "Containment");
300 // the last promoted object may fail the mark() != NULL test of is_oop().
301 guarantee(curObj->next() == NULL || oop(curObj)->is_oop(), "must be an oop");
302 if (curObj->hasDisplacedMark()) {
303 numObjsWithDisplacedHdrs++;
304 }
305 }
306 // Count the number of displaced headers
307 size_t numDisplacedHdrs = 0;
308 for (SpoolBlock* curSpool = _spoolHead;
309 curSpool != _spoolTail && curSpool != NULL;
310 curSpool = curSpool->nextSpoolBlock) {
311 // the first entry is just a self-pointer; indices 1 through
312 // bufferSize - 1 are occupied (thus, bufferSize - 1 slots).
313 guarantee((void*)curSpool->displacedHdr == (void*)&curSpool->displacedHdr,
314 "first entry of displacedHdr should be self-referential");
315 numDisplacedHdrs += curSpool->bufferSize - 1;
316 }
317 guarantee((_spoolHead == _spoolTail) == (numDisplacedHdrs == 0),
318 "internal consistency");
319 guarantee(_spoolTail != NULL || _nextIndex == 1,
320 "Inconsistency between _spoolTail and _nextIndex");
321 // We overcounted (_firstIndex-1) worth of slots in block
322 // _spoolHead and we undercounted (_nextIndex-1) worth of
323 // slots in block _spoolTail. We make an appropriate
324 // adjustment by subtracting the first and adding the
325 // second: - (_firstIndex - 1) + (_nextIndex - 1)
326 numDisplacedHdrs += (_nextIndex - _firstIndex);
327 guarantee(numDisplacedHdrs == numObjsWithDisplacedHdrs, "Displaced hdr count");
328 }
329
330 void PromotionInfo::print_on(outputStream* st) const {
331 SpoolBlock* curSpool = NULL;
332 size_t i = 0;
333 st->print_cr(" start & end indices: [" SIZE_FORMAT ", " SIZE_FORMAT ")",
334 _firstIndex, _nextIndex);
335 for (curSpool = _spoolHead; curSpool != _spoolTail && curSpool != NULL;
336 curSpool = curSpool->nextSpoolBlock) {
337 curSpool->print_on(st);
338 st->print_cr(" active ");
339 i++;
340 }
341 for (curSpool = _spoolTail; curSpool != NULL;
342 curSpool = curSpool->nextSpoolBlock) {
343 curSpool->print_on(st);
344 st->print_cr(" inactive ");
345 i++;
346 }
347 for (curSpool = _spareSpool; curSpool != NULL;
348 curSpool = curSpool->nextSpoolBlock) {
349 curSpool->print_on(st);
350 st->print_cr(" free ");
351 i++;
352 }
353 st->print_cr(" " SIZE_FORMAT " header spooling blocks", i);
354 }
355
356 void SpoolBlock::print_on(outputStream* st) const {
357 st->print("[" PTR_FORMAT "," PTR_FORMAT "), " SIZE_FORMAT " HeapWords -> " PTR_FORMAT,
358 this, (HeapWord*)displacedHdr + bufferSize,
359 bufferSize, nextSpoolBlock);
360 }