1 /*
2 * Copyright (c) 2001, 2013, 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/shared/collectorCounters.hpp"
27 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "memory/blockOffsetTable.inline.hpp"
30 #include "memory/generation.inline.hpp"
31 #include "memory/generationSpec.hpp"
32 #include "memory/space.hpp"
33 #include "memory/tenuredGeneration.hpp"
34 #include "oops/oop.inline.hpp"
35 #include "runtime/java.hpp"
36 #include "utilities/macros.hpp"
37
38 TenuredGeneration::TenuredGeneration(ReservedSpace rs,
39 size_t initial_byte_size, int level,
40 GenRemSet* remset) :
41 OneContigSpaceCardGeneration(rs, initial_byte_size,
42 level, remset, NULL)
43 {
44 HeapWord* bottom = (HeapWord*) _virtual_space.low();
45 HeapWord* end = (HeapWord*) _virtual_space.high();
46 _the_space = new TenuredSpace(_bts, MemRegion(bottom, end));
47 _the_space->reset_saved_mark();
48 _shrink_factor = 0;
49 _capacity_at_prologue = 0;
50
51 _gc_stats = new GCStats();
52
53 // initialize performance counters
54
55 const char* gen_name = "old";
56
57 // Generation Counters -- generation 1, 1 subspace
58 _gen_counters = new GenerationCounters(gen_name, 1, 1, &_virtual_space);
59
60 _gc_counters = new CollectorCounters("MSC", 1);
61
62 _space_counters = new CSpaceCounters(gen_name, 0,
63 _virtual_space.reserved_size(),
64 _the_space, _gen_counters);
65 #if INCLUDE_ALL_GCS
66 if (UseParNewGC) {
67 typedef ParGCAllocBufferWithBOT* ParGCAllocBufferWithBOTPtr;
68 _alloc_buffers = NEW_C_HEAP_ARRAY(ParGCAllocBufferWithBOTPtr,
69 ParallelGCThreads, mtGC);
70 if (_alloc_buffers == NULL)
71 vm_exit_during_initialization("Could not allocate alloc_buffers");
72 for (uint i = 0; i < ParallelGCThreads; i++) {
73 _alloc_buffers[i] =
74 new ParGCAllocBufferWithBOT(OldPLABSize, _bts);
75 if (_alloc_buffers[i] == NULL)
76 vm_exit_during_initialization("Could not allocate alloc_buffers");
77 }
78 } else {
79 _alloc_buffers = NULL;
80 }
81 #endif // INCLUDE_ALL_GCS
82 }
83
84
85 const char* TenuredGeneration::name() const {
86 return "tenured generation";
87 }
88
89 void TenuredGeneration::gc_prologue(bool full) {
90 _capacity_at_prologue = capacity();
91 _used_at_prologue = used();
92 if (VerifyBeforeGC) {
93 verify_alloc_buffers_clean();
94 }
95 }
96
97 void TenuredGeneration::gc_epilogue(bool full) {
98 if (VerifyAfterGC) {
99 verify_alloc_buffers_clean();
100 }
101 OneContigSpaceCardGeneration::gc_epilogue(full);
102 }
103
104
105 bool TenuredGeneration::should_collect(bool full,
106 size_t size,
107 bool is_tlab) {
108 // This should be one big conditional or (||), but I want to be able to tell
109 // why it returns what it returns (without re-evaluating the conditionals
110 // in case they aren't idempotent), so I'm doing it this way.
111 // DeMorgan says it's okay.
112 bool result = false;
113 if (!result && full) {
114 result = true;
115 if (PrintGC && Verbose) {
116 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
117 " full");
118 }
119 }
120 if (!result && should_allocate(size, is_tlab)) {
121 result = true;
122 if (PrintGC && Verbose) {
123 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
124 " should_allocate(" SIZE_FORMAT ")",
125 size);
126 }
127 }
128 // If we don't have very much free space.
129 // XXX: 10000 should be a percentage of the capacity!!!
130 if (!result && free() < 10000) {
131 result = true;
132 if (PrintGC && Verbose) {
133 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
134 " free(): " SIZE_FORMAT,
135 free());
136 }
137 }
138 // If we had to expand to accomodate promotions from younger generations
139 if (!result && _capacity_at_prologue < capacity()) {
140 result = true;
141 if (PrintGC && Verbose) {
142 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
143 "_capacity_at_prologue: " SIZE_FORMAT " < capacity(): " SIZE_FORMAT,
144 _capacity_at_prologue, capacity());
145 }
146 }
147 return result;
148 }
149
150 void TenuredGeneration::collect(bool full,
151 bool clear_all_soft_refs,
152 size_t size,
153 bool is_tlab) {
154 retire_alloc_buffers_before_full_gc();
155 OneContigSpaceCardGeneration::collect(full, clear_all_soft_refs,
156 size, is_tlab);
157 }
158
159 void TenuredGeneration::compute_new_size() {
160 assert_locked_or_safepoint(Heap_lock);
161
162 // Compute some numbers about the state of the heap.
163 const size_t used_after_gc = used();
164 const size_t capacity_after_gc = capacity();
165
166 CardGeneration::compute_new_size();
167
168 assert(used() == used_after_gc && used_after_gc <= capacity(),
169 err_msg("used: " SIZE_FORMAT " used_after_gc: " SIZE_FORMAT
170 " capacity: " SIZE_FORMAT, used(), used_after_gc, capacity()));
171 }
172 void TenuredGeneration::update_gc_stats(int current_level,
173 bool full) {
174 // If the next lower level(s) has been collected, gather any statistics
175 // that are of interest at this point.
176 if (!full && (current_level + 1) == level()) {
177 // Calculate size of data promoted from the younger generations
178 // before doing the collection.
179 size_t used_before_gc = used();
180
181 // If the younger gen collections were skipped, then the
182 // number of promoted bytes will be 0 and adding it to the
183 // average will incorrectly lessen the average. It is, however,
184 // also possible that no promotion was needed.
185 if (used_before_gc >= _used_at_prologue) {
186 size_t promoted_in_bytes = used_before_gc - _used_at_prologue;
187 gc_stats()->avg_promoted()->sample(promoted_in_bytes);
188 }
189 }
190 }
191
192 void TenuredGeneration::update_counters() {
193 if (UsePerfData) {
194 _space_counters->update_all();
195 _gen_counters->update_all();
196 }
197 }
198
199
200 #if INCLUDE_ALL_GCS
201 oop TenuredGeneration::par_promote(int thread_num,
202 oop old, markOop m, size_t word_sz) {
203
204 ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num];
205 HeapWord* obj_ptr = buf->allocate(word_sz);
206 bool is_lab = true;
207 if (obj_ptr == NULL) {
208 #ifndef PRODUCT
209 if (Universe::heap()->promotion_should_fail()) {
210 return NULL;
211 }
212 #endif // #ifndef PRODUCT
213
214 // Slow path:
215 if (word_sz * 100 < ParallelGCBufferWastePct * buf->word_sz()) {
216 // Is small enough; abandon this buffer and start a new one.
217 size_t buf_size = buf->word_sz();
218 HeapWord* buf_space =
219 TenuredGeneration::par_allocate(buf_size, false);
220 if (buf_space == NULL) {
221 buf_space = expand_and_allocate(buf_size, false, true /* parallel*/);
222 }
223 if (buf_space != NULL) {
224 buf->retire(false, false);
225 buf->set_buf(buf_space);
226 obj_ptr = buf->allocate(word_sz);
227 assert(obj_ptr != NULL, "Buffer was definitely big enough...");
228 }
229 };
230 // Otherwise, buffer allocation failed; try allocating object
231 // individually.
232 if (obj_ptr == NULL) {
233 obj_ptr = TenuredGeneration::par_allocate(word_sz, false);
234 if (obj_ptr == NULL) {
235 obj_ptr = expand_and_allocate(word_sz, false, true /* parallel */);
236 }
237 }
238 if (obj_ptr == NULL) return NULL;
239 }
240 assert(obj_ptr != NULL, "program logic");
241 Copy::aligned_disjoint_words((HeapWord*)old, obj_ptr, word_sz);
242 oop obj = oop(obj_ptr);
243 // Restore the mark word copied above.
244 obj->set_mark(m);
245 return obj;
246 }
247
248 void TenuredGeneration::par_promote_alloc_undo(int thread_num,
249 HeapWord* obj,
250 size_t word_sz) {
251 ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num];
252 if (buf->contains(obj)) {
253 guarantee(buf->contains(obj + word_sz - 1),
254 "should contain whole object");
255 buf->undo_allocation(obj, word_sz);
256 } else {
257 CollectedHeap::fill_with_object(obj, word_sz);
258 }
259 }
260
261 void TenuredGeneration::par_promote_alloc_done(int thread_num) {
262 ParGCAllocBufferWithBOT* buf = _alloc_buffers[thread_num];
263 buf->retire(true, ParallelGCRetainPLAB);
264 }
265
266 void TenuredGeneration::retire_alloc_buffers_before_full_gc() {
267 if (UseParNewGC) {
268 for (uint i = 0; i < ParallelGCThreads; i++) {
269 _alloc_buffers[i]->retire(true /*end_of_gc*/, false /*retain*/);
270 }
271 }
272 }
273
274 // Verify that any retained parallel allocation buffers do not
275 // intersect with dirty cards.
276 void TenuredGeneration::verify_alloc_buffers_clean() {
277 if (UseParNewGC) {
278 for (uint i = 0; i < ParallelGCThreads; i++) {
279 _rs->verify_aligned_region_empty(_alloc_buffers[i]->range());
280 }
281 }
282 }
283
284 #else // INCLUDE_ALL_GCS
285 void TenuredGeneration::retire_alloc_buffers_before_full_gc() {}
286 void TenuredGeneration::verify_alloc_buffers_clean() {}
287 #endif // INCLUDE_ALL_GCS
288
289 bool TenuredGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const {
290 size_t available = max_contiguous_available();
291 size_t av_promo = (size_t)gc_stats()->avg_promoted()->padded_average();
292 bool res = (available >= av_promo) || (available >= max_promotion_in_bytes);
293 if (PrintGC && Verbose) {
294 gclog_or_tty->print_cr(
295 "Tenured: promo attempt is%s safe: available("SIZE_FORMAT") %s av_promo("SIZE_FORMAT"),"
296 "max_promo("SIZE_FORMAT")",
297 res? "":" not", available, res? ">=":"<",
298 av_promo, max_promotion_in_bytes);
299 }
300 return res;
301 }