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annotate src/share/vm/gc_implementation/concurrentMarkSweep/promotionInfo.cpp @ 1763:d6f45b55c972
4809552: Optimize Arrays.fill(...)
Reviewed-by: kvn
author | never |
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date | Fri, 27 Aug 2010 17:33:49 -0700 |
parents | be3f9c242c9d |
children | 179464550c7d |
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1521 | 1 /* |
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2 * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved. |
1521 | 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
1521 | 22 * |
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 guarantee((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; | |
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333 st->print_cr(" start & end indices: [" SIZE_FORMAT ", " SIZE_FORMAT ")", |
1521 | 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 } | |
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353 st->print_cr(" " SIZE_FORMAT " header spooling blocks", i); |
1521 | 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 } |