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comparison src/share/vm/gc_implementation/g1/heapRegionSeq.cpp @ 342:37f87013dfd8

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6711316: Open source the Garbage-First garbage collector Summary: First mercurial integration of the code for the Garbage-First garbage collector. Reviewed-by: apetrusenko, iveresov, jmasa, sgoldman, tonyp, ysr
author ysr
date Thu, 05 Jun 2008 15:57:56 -0700
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children 078b8a0d8d7c
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189:0b27f3512f9e 342:37f87013dfd8
1 /*
2 * Copyright 2001-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 #include "incls/_precompiled.incl"
26 #include "incls/_heapRegionSeq.cpp.incl"
27
28 // Local to this file.
29
30 static int orderRegions(HeapRegion** hr1p, HeapRegion** hr2p) {
31 if ((*hr1p)->end() <= (*hr2p)->bottom()) return -1;
32 else if ((*hr2p)->end() <= (*hr1p)->bottom()) return 1;
33 else if (*hr1p == *hr2p) return 0;
34 else {
35 assert(false, "We should never compare distinct overlapping regions.");
36 }
37 return 0;
38 }
39
40 HeapRegionSeq::HeapRegionSeq() :
41 _alloc_search_start(0),
42 // The line below is the worst bit of C++ hackery I've ever written
43 // (Detlefs, 11/23). You should think of it as equivalent to
44 // "_regions(100, true)": initialize the growable array and inform it
45 // that it should allocate its elem array(s) on the C heap. The first
46 // argument, however, is actually a comma expression (new-expr, 100).
47 // The purpose of the new_expr is to inform the growable array that it
48 // is *already* allocated on the C heap: it uses the placement syntax to
49 // keep it from actually doing any allocation.
50 _regions((ResourceObj::operator new (sizeof(GrowableArray<HeapRegion*>),
51 (void*)&_regions,
52 ResourceObj::C_HEAP),
53 100),
54 true),
55 _next_rr_candidate(0),
56 _seq_bottom(NULL)
57 {}
58
59 // Private methods.
60
61 HeapWord*
62 HeapRegionSeq::alloc_obj_from_region_index(int ind, size_t word_size) {
63 assert(G1CollectedHeap::isHumongous(word_size),
64 "Allocation size should be humongous");
65 int cur = ind;
66 int first = cur;
67 size_t sumSizes = 0;
68 while (cur < _regions.length() && sumSizes < word_size) {
69 // Loop invariant:
70 // For all i in [first, cur):
71 // _regions.at(i)->is_empty()
72 // && _regions.at(i) is contiguous with its predecessor, if any
73 // && sumSizes is the sum of the sizes of the regions in the interval
74 // [first, cur)
75 HeapRegion* curhr = _regions.at(cur);
76 if (curhr->is_empty()
77 && !curhr->is_reserved()
78 && (first == cur
79 || (_regions.at(cur-1)->end() ==
80 curhr->bottom()))) {
81 sumSizes += curhr->capacity() / HeapWordSize;
82 } else {
83 first = cur + 1;
84 sumSizes = 0;
85 }
86 cur++;
87 }
88 if (sumSizes >= word_size) {
89 _alloc_search_start = cur;
90 // Mark the allocated regions as allocated.
91 bool zf = G1CollectedHeap::heap()->allocs_are_zero_filled();
92 HeapRegion* first_hr = _regions.at(first);
93 for (int i = first; i < cur; i++) {
94 HeapRegion* hr = _regions.at(i);
95 if (zf)
96 hr->ensure_zero_filled();
97 {
98 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
99 hr->set_zero_fill_allocated();
100 }
101 size_t sz = hr->capacity() / HeapWordSize;
102 HeapWord* tmp = hr->allocate(sz);
103 assert(tmp != NULL, "Humongous allocation failure");
104 MemRegion mr = MemRegion(tmp, sz);
105 SharedHeap::fill_region_with_object(mr);
106 hr->declare_filled_region_to_BOT(mr);
107 if (i == first) {
108 first_hr->set_startsHumongous();
109 } else {
110 assert(i > first, "sanity");
111 hr->set_continuesHumongous(first_hr);
112 }
113 }
114 HeapWord* first_hr_bot = first_hr->bottom();
115 HeapWord* obj_end = first_hr_bot + word_size;
116 first_hr->set_top(obj_end);
117 return first_hr_bot;
118 } else {
119 // If we started from the beginning, we want to know why we can't alloc.
120 return NULL;
121 }
122 }
123
124 void HeapRegionSeq::print_empty_runs(bool reserved_are_empty) {
125 int empty_run = 0;
126 int n_empty = 0;
127 bool at_least_one_reserved = false;
128 int empty_run_start;
129 for (int i = 0; i < _regions.length(); i++) {
130 HeapRegion* r = _regions.at(i);
131 if (r->continuesHumongous()) continue;
132 if (r->is_empty() && (reserved_are_empty || !r->is_reserved())) {
133 assert(!r->isHumongous(), "H regions should not be empty.");
134 if (empty_run == 0) empty_run_start = i;
135 empty_run++;
136 n_empty++;
137 if (r->is_reserved()) {
138 at_least_one_reserved = true;
139 }
140 } else {
141 if (empty_run > 0) {
142 gclog_or_tty->print(" %d:%d", empty_run_start, empty_run);
143 if (reserved_are_empty && at_least_one_reserved)
144 gclog_or_tty->print("(R)");
145 empty_run = 0;
146 at_least_one_reserved = false;
147 }
148 }
149 }
150 if (empty_run > 0) {
151 gclog_or_tty->print(" %d:%d", empty_run_start, empty_run);
152 if (reserved_are_empty && at_least_one_reserved) gclog_or_tty->print("(R)");
153 }
154 gclog_or_tty->print_cr(" [tot = %d]", n_empty);
155 }
156
157 int HeapRegionSeq::find(HeapRegion* hr) {
158 // FIXME: optimized for adjacent regions of fixed size.
159 int ind = hr->hrs_index();
160 if (ind != -1) {
161 assert(_regions.at(ind) == hr, "Mismatch");
162 }
163 return ind;
164 }
165
166
167 // Public methods.
168
169 void HeapRegionSeq::insert(HeapRegion* hr) {
170 if (_regions.length() == 0
171 || _regions.top()->end() <= hr->bottom()) {
172 hr->set_hrs_index(_regions.length());
173 _regions.append(hr);
174 } else {
175 _regions.append(hr);
176 _regions.sort(orderRegions);
177 for (int i = 0; i < _regions.length(); i++) {
178 _regions.at(i)->set_hrs_index(i);
179 }
180 }
181 char* bot = (char*)_regions.at(0)->bottom();
182 if (_seq_bottom == NULL || bot < _seq_bottom) _seq_bottom = bot;
183 }
184
185 size_t HeapRegionSeq::length() {
186 return _regions.length();
187 }
188
189 size_t HeapRegionSeq::free_suffix() {
190 size_t res = 0;
191 int first = _regions.length() - 1;
192 int cur = first;
193 while (cur >= 0 &&
194 (_regions.at(cur)->is_empty()
195 && !_regions.at(cur)->is_reserved()
196 && (first == cur
197 || (_regions.at(cur+1)->bottom() ==
198 _regions.at(cur)->end())))) {
199 res++;
200 cur--;
201 }
202 return res;
203 }
204
205 HeapWord* HeapRegionSeq::obj_allocate(size_t word_size) {
206 int cur = _alloc_search_start;
207 // Make sure "cur" is a valid index.
208 assert(cur >= 0, "Invariant.");
209 HeapWord* res = alloc_obj_from_region_index(cur, word_size);
210 if (res == NULL)
211 res = alloc_obj_from_region_index(0, word_size);
212 return res;
213 }
214
215 void HeapRegionSeq::iterate(HeapRegionClosure* blk) {
216 iterate_from((HeapRegion*)NULL, blk);
217 }
218
219 // The first argument r is the heap region at which iteration begins.
220 // This operation runs fastest when r is NULL, or the heap region for
221 // which a HeapRegionClosure most recently returned true, or the
222 // heap region immediately to its right in the sequence. In all
223 // other cases a linear search is required to find the index of r.
224
225 void HeapRegionSeq::iterate_from(HeapRegion* r, HeapRegionClosure* blk) {
226
227 // :::: FIXME ::::
228 // Static cache value is bad, especially when we start doing parallel
229 // remembered set update. For now just don't cache anything (the
230 // code in the def'd out blocks).
231
232 #if 0
233 static int cached_j = 0;
234 #endif
235 int len = _regions.length();
236 int j = 0;
237 // Find the index of r.
238 if (r != NULL) {
239 #if 0
240 assert(cached_j >= 0, "Invariant.");
241 if ((cached_j < len) && (r == _regions.at(cached_j))) {
242 j = cached_j;
243 } else if ((cached_j + 1 < len) && (r == _regions.at(cached_j + 1))) {
244 j = cached_j + 1;
245 } else {
246 j = find(r);
247 #endif
248 if (j < 0) {
249 j = 0;
250 }
251 #if 0
252 }
253 #endif
254 }
255 int i;
256 for (i = j; i < len; i += 1) {
257 int res = blk->doHeapRegion(_regions.at(i));
258 if (res) {
259 #if 0
260 cached_j = i;
261 #endif
262 blk->incomplete();
263 return;
264 }
265 }
266 for (i = 0; i < j; i += 1) {
267 int res = blk->doHeapRegion(_regions.at(i));
268 if (res) {
269 #if 0
270 cached_j = i;
271 #endif
272 blk->incomplete();
273 return;
274 }
275 }
276 }
277
278 void HeapRegionSeq::iterate_from(int idx, HeapRegionClosure* blk) {
279 int len = _regions.length();
280 int i;
281 for (i = idx; i < len; i++) {
282 if (blk->doHeapRegion(_regions.at(i))) {
283 blk->incomplete();
284 return;
285 }
286 }
287 for (i = 0; i < idx; i++) {
288 if (blk->doHeapRegion(_regions.at(i))) {
289 blk->incomplete();
290 return;
291 }
292 }
293 }
294
295 MemRegion HeapRegionSeq::shrink_by(size_t shrink_bytes,
296 size_t& num_regions_deleted) {
297 assert(shrink_bytes % os::vm_page_size() == 0, "unaligned");
298 assert(shrink_bytes % HeapRegion::GrainBytes == 0, "unaligned");
299
300 if (_regions.length() == 0) {
301 num_regions_deleted = 0;
302 return MemRegion();
303 }
304 int j = _regions.length() - 1;
305 HeapWord* end = _regions.at(j)->end();
306 HeapWord* last_start = end;
307 while (j >= 0 && shrink_bytes > 0) {
308 HeapRegion* cur = _regions.at(j);
309 // We have to leave humongous regions where they are,
310 // and work around them.
311 if (cur->isHumongous()) {
312 return MemRegion(last_start, end);
313 }
314 cur->reset_zero_fill();
315 assert(cur == _regions.top(), "Should be top");
316 if (!cur->is_empty()) break;
317 shrink_bytes -= cur->capacity();
318 num_regions_deleted++;
319 _regions.pop();
320 last_start = cur->bottom();
321 // We need to delete these somehow, but can't currently do so here: if
322 // we do, the ZF thread may still access the deleted region. We'll
323 // leave this here as a reminder that we have to do something about
324 // this.
325 // delete cur;
326 j--;
327 }
328 return MemRegion(last_start, end);
329 }
330
331
332 class PrintHeapRegionClosure : public HeapRegionClosure {
333 public:
334 bool doHeapRegion(HeapRegion* r) {
335 gclog_or_tty->print(PTR_FORMAT ":", r);
336 r->print();
337 return false;
338 }
339 };
340
341 void HeapRegionSeq::print() {
342 PrintHeapRegionClosure cl;
343 iterate(&cl);
344 }