1 /*
2 * Copyright (c) 2001, 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.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc_implementation/g1/collectionSetChooser.hpp"
27 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
28 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
29 #include "memory/space.inline.hpp"
30
31 CSetChooserCache::CSetChooserCache() {
32 for (int i = 0; i < CacheLength; ++i)
33 _cache[i] = NULL;
34 clear();
35 }
36
37 void CSetChooserCache::clear() {
38 _occupancy = 0;
39 _first = 0;
40 for (int i = 0; i < CacheLength; ++i) {
41 HeapRegion *hr = _cache[i];
42 if (hr != NULL)
43 hr->set_sort_index(-1);
44 _cache[i] = NULL;
45 }
46 }
47
48 #ifndef PRODUCT
49 bool CSetChooserCache::verify() {
50 int index = _first;
51 HeapRegion *prev = NULL;
52 for (int i = 0; i < _occupancy; ++i) {
53 guarantee(_cache[index] != NULL, "cache entry should not be empty");
54 HeapRegion *hr = _cache[index];
55 guarantee(!hr->is_young(), "should not be young!");
56 if (prev != NULL) {
57 guarantee(prev->gc_efficiency() >= hr->gc_efficiency(),
58 "cache should be correctly ordered");
59 }
60 guarantee(hr->sort_index() == get_sort_index(index),
61 "sort index should be correct");
62 index = trim_index(index + 1);
63 prev = hr;
64 }
65
66 for (int i = 0; i < (CacheLength - _occupancy); ++i) {
67 guarantee(_cache[index] == NULL, "cache entry should be empty");
68 index = trim_index(index + 1);
69 }
70
71 guarantee(index == _first, "we should have reached where we started from");
72 return true;
73 }
74 #endif // PRODUCT
75
76 void CSetChooserCache::insert(HeapRegion *hr) {
77 assert(!is_full(), "cache should not be empty");
78 hr->calc_gc_efficiency();
79
80 int empty_index;
81 if (_occupancy == 0) {
82 empty_index = _first;
83 } else {
84 empty_index = trim_index(_first + _occupancy);
85 assert(_cache[empty_index] == NULL, "last slot should be empty");
86 int last_index = trim_index(empty_index - 1);
87 HeapRegion *last = _cache[last_index];
88 assert(last != NULL,"as the cache is not empty, last should not be empty");
89 while (empty_index != _first &&
90 last->gc_efficiency() < hr->gc_efficiency()) {
91 _cache[empty_index] = last;
92 last->set_sort_index(get_sort_index(empty_index));
93 empty_index = last_index;
94 last_index = trim_index(last_index - 1);
95 last = _cache[last_index];
96 }
97 }
98 _cache[empty_index] = hr;
99 hr->set_sort_index(get_sort_index(empty_index));
100
101 ++_occupancy;
102 assert(verify(), "cache should be consistent");
103 }
104
105 HeapRegion *CSetChooserCache::remove_first() {
106 if (_occupancy > 0) {
107 assert(_cache[_first] != NULL, "cache should have at least one region");
108 HeapRegion *ret = _cache[_first];
109 _cache[_first] = NULL;
110 ret->set_sort_index(-1);
111 --_occupancy;
112 _first = trim_index(_first + 1);
113 assert(verify(), "cache should be consistent");
114 return ret;
115 } else {
116 return NULL;
117 }
118 }
119
120 // this is a bit expensive... but we expect that it should not be called
121 // to often.
122 void CSetChooserCache::remove(HeapRegion *hr) {
123 assert(_occupancy > 0, "cache should not be empty");
124 assert(hr->sort_index() < -1, "should already be in the cache");
125 int index = get_index(hr->sort_index());
126 assert(_cache[index] == hr, "index should be correct");
127 int next_index = trim_index(index + 1);
128 int last_index = trim_index(_first + _occupancy - 1);
129 while (index != last_index) {
130 assert(_cache[next_index] != NULL, "should not be null");
131 _cache[index] = _cache[next_index];
132 _cache[index]->set_sort_index(get_sort_index(index));
133
134 index = next_index;
135 next_index = trim_index(next_index+1);
136 }
137 assert(index == last_index, "should have reached the last one");
138 _cache[index] = NULL;
139 hr->set_sort_index(-1);
140 --_occupancy;
141 assert(verify(), "cache should be consistent");
142 }
143
144 static inline int orderRegions(HeapRegion* hr1, HeapRegion* hr2) {
145 if (hr1 == NULL) {
146 if (hr2 == NULL) return 0;
147 else return 1;
148 } else if (hr2 == NULL) {
149 return -1;
150 }
151 if (hr2->gc_efficiency() < hr1->gc_efficiency()) return -1;
152 else if (hr1->gc_efficiency() < hr2->gc_efficiency()) return 1;
153 else return 0;
154 }
155
156 static int orderRegions(HeapRegion** hr1p, HeapRegion** hr2p) {
157 return orderRegions(*hr1p, *hr2p);
158 }
159
160 CollectionSetChooser::CollectionSetChooser() :
161 // The line below is the worst bit of C++ hackery I've ever written
162 // (Detlefs, 11/23). You should think of it as equivalent to
163 // "_regions(100, true)": initialize the growable array and inform it
164 // that it should allocate its elem array(s) on the C heap.
165 //
166 // The first argument, however, is actually a comma expression
167 // (set_allocation_type(this, C_HEAP), 100). The purpose of the
168 // set_allocation_type() call is to replace the default allocation
169 // type for embedded objects STACK_OR_EMBEDDED with C_HEAP. It will
170 // allow to pass the assert in GenericGrowableArray() which checks
171 // that a growable array object must be on C heap if elements are.
172 //
173 // Note: containing object is allocated on C heap since it is CHeapObj.
174 //
175 _markedRegions((ResourceObj::set_allocation_type((address)&_markedRegions,
176 ResourceObj::C_HEAP),
177 100),
178 true),
179 _curMarkedIndex(0),
180 _numMarkedRegions(0),
181 _unmarked_age_1_returned_as_new(false),
182 _first_par_unreserved_idx(0)
183 {}
184
185
186
187 #ifndef PRODUCT
188 bool CollectionSetChooser::verify() {
189 int index = 0;
190 guarantee(_curMarkedIndex <= _numMarkedRegions,
191 "_curMarkedIndex should be within bounds");
192 while (index < _curMarkedIndex) {
193 guarantee(_markedRegions.at(index++) == NULL,
194 "all entries before _curMarkedIndex should be NULL");
195 }
196 HeapRegion *prev = NULL;
197 while (index < _numMarkedRegions) {
198 HeapRegion *curr = _markedRegions.at(index++);
199 if (curr != NULL) {
200 int si = curr->sort_index();
201 guarantee(!curr->is_young(), "should not be young!");
202 guarantee(si > -1 && si == (index-1), "sort index invariant");
203 if (prev != NULL) {
204 guarantee(orderRegions(prev, curr) != 1, "regions should be sorted");
205 }
206 prev = curr;
207 }
208 }
209 return _cache.verify();
210 }
211 #endif
212
213 bool
214 CollectionSetChooser::addRegionToCache() {
215 assert(!_cache.is_full(), "cache should not be full");
216
217 HeapRegion *hr = NULL;
218 while (hr == NULL && _curMarkedIndex < _numMarkedRegions) {
219 hr = _markedRegions.at(_curMarkedIndex++);
220 }
221 if (hr == NULL)
222 return false;
223 assert(!hr->is_young(), "should not be young!");
224 assert(hr->sort_index() == _curMarkedIndex-1, "sort_index invariant");
225 _markedRegions.at_put(hr->sort_index(), NULL);
226 _cache.insert(hr);
227 assert(!_cache.is_empty(), "cache should not be empty");
228 assert(verify(), "cache should be consistent");
229 return false;
230 }
231
232 void
233 CollectionSetChooser::fillCache() {
234 while (!_cache.is_full() && addRegionToCache()) {
235 }
236 }
237
238 void
239 CollectionSetChooser::sortMarkedHeapRegions() {
240 guarantee(_cache.is_empty(), "cache should be empty");
241 // First trim any unused portion of the top in the parallel case.
242 if (_first_par_unreserved_idx > 0) {
243 if (G1PrintParCleanupStats) {
244 gclog_or_tty->print(" Truncating _markedRegions from %d to %d.\n",
245 _markedRegions.length(), _first_par_unreserved_idx);
246 }
247 assert(_first_par_unreserved_idx <= _markedRegions.length(),
248 "Or we didn't reserved enough length");
249 _markedRegions.trunc_to(_first_par_unreserved_idx);
250 }
251 _markedRegions.sort(orderRegions);
252 assert(_numMarkedRegions <= _markedRegions.length(), "Requirement");
253 assert(_numMarkedRegions == 0
254 || _markedRegions.at(_numMarkedRegions-1) != NULL,
255 "Testing _numMarkedRegions");
256 assert(_numMarkedRegions == _markedRegions.length()
257 || _markedRegions.at(_numMarkedRegions) == NULL,
258 "Testing _numMarkedRegions");
259 if (G1PrintParCleanupStats) {
260 gclog_or_tty->print_cr(" Sorted %d marked regions.", _numMarkedRegions);
261 }
262 for (int i = 0; i < _numMarkedRegions; i++) {
263 assert(_markedRegions.at(i) != NULL, "Should be true by sorting!");
264 _markedRegions.at(i)->set_sort_index(i);
265 if (G1PrintRegionLivenessInfo > 0) {
266 if (i == 0) gclog_or_tty->print_cr("Sorted marked regions:");
267 if (i < G1PrintRegionLivenessInfo ||
268 (_numMarkedRegions-i) < G1PrintRegionLivenessInfo) {
269 HeapRegion* hr = _markedRegions.at(i);
270 size_t u = hr->used();
271 gclog_or_tty->print_cr(" Region %d: %d used, %d max live, %5.2f%%.",
272 i, u, hr->max_live_bytes(),
273 100.0*(float)hr->max_live_bytes()/(float)u);
274 }
275 }
276 }
277 if (G1PolicyVerbose > 1)
278 printSortedHeapRegions();
279 assert(verify(), "should now be sorted");
280 }
281
282 void
283 printHeapRegion(HeapRegion *hr) {
284 if (hr->isHumongous())
285 gclog_or_tty->print("H: ");
286 if (hr->in_collection_set())
287 gclog_or_tty->print("CS: ");
288 gclog_or_tty->print_cr("Region " PTR_FORMAT " (%s%s) "
289 "[" PTR_FORMAT ", " PTR_FORMAT"] "
290 "Used: " SIZE_FORMAT "K, garbage: " SIZE_FORMAT "K.",
291 hr, hr->is_young() ? "Y " : " ",
292 hr->is_marked()? "M1" : "M0",
293 hr->bottom(), hr->end(),
294 hr->used()/K, hr->garbage_bytes()/K);
295 }
296
297 void
298 CollectionSetChooser::addMarkedHeapRegion(HeapRegion* hr) {
299 assert(!hr->isHumongous(),
300 "Humongous regions shouldn't be added to the collection set");
301 assert(!hr->is_young(), "should not be young!");
302 _markedRegions.append(hr);
303 _numMarkedRegions++;
304 hr->calc_gc_efficiency();
305 }
306
307 void
308 CollectionSetChooser::
309 prepareForAddMarkedHeapRegionsPar(size_t n_regions, size_t chunkSize) {
310 _first_par_unreserved_idx = 0;
311 size_t max_waste = ParallelGCThreads * chunkSize;
312 // it should be aligned with respect to chunkSize
313 size_t aligned_n_regions =
314 (n_regions + (chunkSize - 1)) / chunkSize * chunkSize;
315 assert( aligned_n_regions % chunkSize == 0, "should be aligned" );
316 _markedRegions.at_put_grow((int)(aligned_n_regions + max_waste - 1), NULL);
317 }
318
319 jint
320 CollectionSetChooser::getParMarkedHeapRegionChunk(jint n_regions) {
321 jint res = Atomic::add(n_regions, &_first_par_unreserved_idx);
322 assert(_markedRegions.length() > res + n_regions - 1,
323 "Should already have been expanded");
324 return res - n_regions;
325 }
326
327 void
328 CollectionSetChooser::setMarkedHeapRegion(jint index, HeapRegion* hr) {
329 assert(_markedRegions.at(index) == NULL, "precondition");
330 assert(!hr->is_young(), "should not be young!");
331 _markedRegions.at_put(index, hr);
332 hr->calc_gc_efficiency();
333 }
334
335 void
336 CollectionSetChooser::incNumMarkedHeapRegions(jint inc_by) {
337 (void)Atomic::add(inc_by, &_numMarkedRegions);
338 }
339
340 void
341 CollectionSetChooser::clearMarkedHeapRegions(){
342 for (int i = 0; i < _markedRegions.length(); i++) {
343 HeapRegion* r = _markedRegions.at(i);
344 if (r != NULL) r->set_sort_index(-1);
345 }
346 _markedRegions.clear();
347 _curMarkedIndex = 0;
348 _numMarkedRegions = 0;
349 _cache.clear();
350 };
351
352 void
353 CollectionSetChooser::updateAfterFullCollection() {
354 G1CollectedHeap* g1h = G1CollectedHeap::heap();
355 clearMarkedHeapRegions();
356 }
357
358 void
359 CollectionSetChooser::printSortedHeapRegions() {
360 gclog_or_tty->print_cr("Printing %d Heap Regions sorted by amount of known garbage",
361 _numMarkedRegions);
362
363 DEBUG_ONLY(int marked_count = 0;)
364 for (int i = 0; i < _markedRegions.length(); i++) {
365 HeapRegion* r = _markedRegions.at(i);
366 if (r != NULL) {
367 printHeapRegion(r);
368 DEBUG_ONLY(marked_count++;)
369 }
370 }
371 assert(marked_count == _numMarkedRegions, "must be");
372 gclog_or_tty->print_cr("Done sorted heap region print");
373 }
374
375 void CollectionSetChooser::removeRegion(HeapRegion *hr) {
376 int si = hr->sort_index();
377 assert(si == -1 || hr->is_marked(), "Sort index not valid.");
378 if (si > -1) {
379 assert(_markedRegions.at(si) == hr, "Sort index not valid." );
380 _markedRegions.at_put(si, NULL);
381 } else if (si < -1) {
382 assert(_cache.region_in_cache(hr), "should be in the cache");
383 _cache.remove(hr);
384 assert(hr->sort_index() == -1, "sort index invariant");
385 }
386 hr->set_sort_index(-1);
387 }
388
389 // if time_remaining < 0.0, then this method should try to return
390 // a region, whether it fits within the remaining time or not
391 HeapRegion*
392 CollectionSetChooser::getNextMarkedRegion(double time_remaining,
393 double avg_prediction) {
394 G1CollectedHeap* g1h = G1CollectedHeap::heap();
395 G1CollectorPolicy* g1p = g1h->g1_policy();
396 fillCache();
397 if (_cache.is_empty()) {
398 assert(_curMarkedIndex == _numMarkedRegions,
399 "if cache is empty, list should also be empty");
400 return NULL;
401 }
402
403 HeapRegion *hr = _cache.get_first();
404 assert(hr != NULL, "if cache not empty, first entry should be non-null");
405 double predicted_time = g1h->predict_region_elapsed_time_ms(hr, false);
406
407 if (g1p->adaptive_young_list_length()) {
408 if (time_remaining - predicted_time < 0.0) {
409 g1h->check_if_region_is_too_expensive(predicted_time);
410 return NULL;
411 }
412 } else {
413 if (predicted_time > 2.0 * avg_prediction) {
414 return NULL;
415 }
416 }
417
418 HeapRegion *hr2 = _cache.remove_first();
419 assert(hr == hr2, "cache contents should not have changed");
420
421 return hr;
422 }