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/g1CollectedHeap.inline.hpp"
27 #include "gc_implementation/g1/heapRegionSeq.hpp"
28 #include "memory/allocation.hpp"
29
30 // Local to this file.
31
32 static int orderRegions(HeapRegion** hr1p, HeapRegion** hr2p) {
33 if ((*hr1p)->end() <= (*hr2p)->bottom()) return -1;
34 else if ((*hr2p)->end() <= (*hr1p)->bottom()) return 1;
35 else if (*hr1p == *hr2p) return 0;
36 else {
37 assert(false, "We should never compare distinct overlapping regions.");
38 }
39 return 0;
40 }
41
42 HeapRegionSeq::HeapRegionSeq(const size_t max_size) :
43 _alloc_search_start(0),
44 // The line below is the worst bit of C++ hackery I've ever written
45 // (Detlefs, 11/23). You should think of it as equivalent to
46 // "_regions(100, true)": initialize the growable array and inform it
47 // that it should allocate its elem array(s) on the C heap.
48 //
49 // The first argument, however, is actually a comma expression
50 // (set_allocation_type(this, C_HEAP), 100). The purpose of the
51 // set_allocation_type() call is to replace the default allocation
52 // type for embedded objects STACK_OR_EMBEDDED with C_HEAP. It will
53 // allow to pass the assert in GenericGrowableArray() which checks
54 // that a growable array object must be on C heap if elements are.
55 //
56 // Note: containing object is allocated on C heap since it is CHeapObj.
57 //
58 _regions((ResourceObj::set_allocation_type((address)&_regions,
59 ResourceObj::C_HEAP),
60 (int)max_size),
61 true),
62 _next_rr_candidate(0),
63 _seq_bottom(NULL)
64 {}
65
66 // Private methods.
67
68 HeapWord*
69 HeapRegionSeq::alloc_obj_from_region_index(int ind, size_t word_size) {
70 assert(G1CollectedHeap::isHumongous(word_size),
71 "Allocation size should be humongous");
72 int cur = ind;
73 int first = cur;
74 size_t sumSizes = 0;
75 while (cur < _regions.length() && sumSizes < word_size) {
76 // Loop invariant:
77 // For all i in [first, cur):
78 // _regions.at(i)->is_empty()
79 // && _regions.at(i) is contiguous with its predecessor, if any
80 // && sumSizes is the sum of the sizes of the regions in the interval
81 // [first, cur)
82 HeapRegion* curhr = _regions.at(cur);
83 if (curhr->is_empty()
84 && (first == cur
85 || (_regions.at(cur-1)->end() ==
86 curhr->bottom()))) {
87 sumSizes += curhr->capacity() / HeapWordSize;
88 } else {
89 first = cur + 1;
90 sumSizes = 0;
91 }
92 cur++;
93 }
94 if (sumSizes >= word_size) {
95 _alloc_search_start = cur;
96 // Mark the allocated regions as allocated.
97 bool zf = G1CollectedHeap::heap()->allocs_are_zero_filled();
98 HeapRegion* first_hr = _regions.at(first);
99 for (int i = first; i < cur; i++) {
100 HeapRegion* hr = _regions.at(i);
101 if (zf)
102 hr->ensure_zero_filled();
103 {
104 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);
105 hr->set_zero_fill_allocated();
106 }
107 size_t sz = hr->capacity() / HeapWordSize;
108 HeapWord* tmp = hr->allocate(sz);
109 assert(tmp != NULL, "Humongous allocation failure");
110 MemRegion mr = MemRegion(tmp, sz);
111 CollectedHeap::fill_with_object(mr);
112 hr->declare_filled_region_to_BOT(mr);
113 if (i == first) {
114 first_hr->set_startsHumongous();
115 } else {
116 assert(i > first, "sanity");
117 hr->set_continuesHumongous(first_hr);
118 }
119 }
120 HeapWord* first_hr_bot = first_hr->bottom();
121 HeapWord* obj_end = first_hr_bot + word_size;
122 first_hr->set_top(obj_end);
123 return first_hr_bot;
124 } else {
125 // If we started from the beginning, we want to know why we can't alloc.
126 return NULL;
127 }
128 }
129
130 void HeapRegionSeq::print_empty_runs() {
131 int empty_run = 0;
132 int n_empty = 0;
133 int empty_run_start;
134 for (int i = 0; i < _regions.length(); i++) {
135 HeapRegion* r = _regions.at(i);
136 if (r->continuesHumongous()) continue;
137 if (r->is_empty()) {
138 assert(!r->isHumongous(), "H regions should not be empty.");
139 if (empty_run == 0) empty_run_start = i;
140 empty_run++;
141 n_empty++;
142 } else {
143 if (empty_run > 0) {
144 gclog_or_tty->print(" %d:%d", empty_run_start, empty_run);
145 empty_run = 0;
146 }
147 }
148 }
149 if (empty_run > 0) {
150 gclog_or_tty->print(" %d:%d", empty_run_start, empty_run);
151 }
152 gclog_or_tty->print_cr(" [tot = %d]", n_empty);
153 }
154
155 int HeapRegionSeq::find(HeapRegion* hr) {
156 // FIXME: optimized for adjacent regions of fixed size.
157 int ind = hr->hrs_index();
158 if (ind != -1) {
159 assert(_regions.at(ind) == hr, "Mismatch");
160 }
161 return ind;
162 }
163
164
165 // Public methods.
166
167 void HeapRegionSeq::insert(HeapRegion* hr) {
168 assert(!_regions.is_full(), "Too many elements in HeapRegionSeq");
169 if (_regions.length() == 0
170 || _regions.top()->end() <= hr->bottom()) {
171 hr->set_hrs_index(_regions.length());
172 _regions.append(hr);
173 } else {
174 _regions.append(hr);
175 _regions.sort(orderRegions);
176 for (int i = 0; i < _regions.length(); i++) {
177 _regions.at(i)->set_hrs_index(i);
178 }
179 }
180 char* bot = (char*)_regions.at(0)->bottom();
181 if (_seq_bottom == NULL || bot < _seq_bottom) _seq_bottom = bot;
182 }
183
184 size_t HeapRegionSeq::length() {
185 return _regions.length();
186 }
187
188 size_t HeapRegionSeq::free_suffix() {
189 size_t res = 0;
190 int first = _regions.length() - 1;
191 int cur = first;
192 while (cur >= 0 &&
193 (_regions.at(cur)->is_empty()
194 && (first == cur
195 || (_regions.at(cur+1)->bottom() ==
196 _regions.at(cur)->end())))) {
197 res++;
198 cur--;
199 }
200 return res;
201 }
202
203 HeapWord* HeapRegionSeq::obj_allocate(size_t word_size) {
204 int cur = _alloc_search_start;
205 // Make sure "cur" is a valid index.
206 assert(cur >= 0, "Invariant.");
207 HeapWord* res = alloc_obj_from_region_index(cur, word_size);
208 if (res == NULL)
209 res = alloc_obj_from_region_index(0, word_size);
210 return res;
211 }
212
213 void HeapRegionSeq::iterate(HeapRegionClosure* blk) {
214 iterate_from((HeapRegion*)NULL, blk);
215 }
216
217 // The first argument r is the heap region at which iteration begins.
218 // This operation runs fastest when r is NULL, or the heap region for
219 // which a HeapRegionClosure most recently returned true, or the
220 // heap region immediately to its right in the sequence. In all
221 // other cases a linear search is required to find the index of r.
222
223 void HeapRegionSeq::iterate_from(HeapRegion* r, HeapRegionClosure* blk) {
224
225 // :::: FIXME ::::
226 // Static cache value is bad, especially when we start doing parallel
227 // remembered set update. For now just don't cache anything (the
228 // code in the def'd out blocks).
229
230 #if 0
231 static int cached_j = 0;
232 #endif
233 int len = _regions.length();
234 int j = 0;
235 // Find the index of r.
236 if (r != NULL) {
237 #if 0
238 assert(cached_j >= 0, "Invariant.");
239 if ((cached_j < len) && (r == _regions.at(cached_j))) {
240 j = cached_j;
241 } else if ((cached_j + 1 < len) && (r == _regions.at(cached_j + 1))) {
242 j = cached_j + 1;
243 } else {
244 j = find(r);
245 #endif
246 if (j < 0) {
247 j = 0;
248 }
249 #if 0
250 }
251 #endif
252 }
253 int i;
254 for (i = j; i < len; i += 1) {
255 int res = blk->doHeapRegion(_regions.at(i));
256 if (res) {
257 #if 0
258 cached_j = i;
259 #endif
260 blk->incomplete();
261 return;
262 }
263 }
264 for (i = 0; i < j; i += 1) {
265 int res = blk->doHeapRegion(_regions.at(i));
266 if (res) {
267 #if 0
268 cached_j = i;
269 #endif
270 blk->incomplete();
271 return;
272 }
273 }
274 }
275
276 void HeapRegionSeq::iterate_from(int idx, HeapRegionClosure* blk) {
277 int len = _regions.length();
278 int i;
279 for (i = idx; i < len; i++) {
280 if (blk->doHeapRegion(_regions.at(i))) {
281 blk->incomplete();
282 return;
283 }
284 }
285 for (i = 0; i < idx; i++) {
286 if (blk->doHeapRegion(_regions.at(i))) {
287 blk->incomplete();
288 return;
289 }
290 }
291 }
292
293 MemRegion HeapRegionSeq::shrink_by(size_t shrink_bytes,
294 size_t& num_regions_deleted) {
295 assert(shrink_bytes % os::vm_page_size() == 0, "unaligned");
296 assert(shrink_bytes % HeapRegion::GrainBytes == 0, "unaligned");
297
298 if (_regions.length() == 0) {
299 num_regions_deleted = 0;
300 return MemRegion();
301 }
302 int j = _regions.length() - 1;
303 HeapWord* end = _regions.at(j)->end();
304 HeapWord* last_start = end;
305 while (j >= 0 && shrink_bytes > 0) {
306 HeapRegion* cur = _regions.at(j);
307 // We have to leave humongous regions where they are,
308 // and work around them.
309 if (cur->isHumongous()) {
310 return MemRegion(last_start, end);
311 }
312 assert(cur == _regions.top(), "Should be top");
313 if (!cur->is_empty()) break;
314 cur->reset_zero_fill();
315 shrink_bytes -= cur->capacity();
316 num_regions_deleted++;
317 _regions.pop();
318 last_start = cur->bottom();
319 // We need to delete these somehow, but can't currently do so here: if
320 // we do, the ZF thread may still access the deleted region. We'll
321 // leave this here as a reminder that we have to do something about
322 // this.
323 // delete cur;
324 j--;
325 }
326 return MemRegion(last_start, end);
327 }
328
329
330 class PrintHeapRegionClosure : public HeapRegionClosure {
331 public:
332 bool doHeapRegion(HeapRegion* r) {
333 gclog_or_tty->print(PTR_FORMAT ":", r);
334 r->print();
335 return false;
336 }
337 };
338
339 void HeapRegionSeq::print() {
340 PrintHeapRegionClosure cl;
341 iterate(&cl);
342 }