1 /*
2 * Copyright (c) 2001, 2015, 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/gcTimer.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "memory/blockOffsetTable.inline.hpp"
30 #include "memory/cardGeneration.inline.hpp"
31 #include "memory/generationSpec.hpp"
32 #include "memory/genMarkSweep.hpp"
33 #include "memory/genOopClosures.inline.hpp"
34 #include "memory/space.hpp"
35 #include "memory/tenuredGeneration.inline.hpp"
36 #include "oops/oop.inline.hpp"
37 #include "runtime/java.hpp"
38 #include "utilities/macros.hpp"
39
40 TenuredGeneration::TenuredGeneration(ReservedSpace rs,
41 size_t initial_byte_size, int level,
42 GenRemSet* remset) :
43 CardGeneration(rs, initial_byte_size, level, remset)
44 {
45 HeapWord* bottom = (HeapWord*) _virtual_space.low();
46 HeapWord* end = (HeapWord*) _virtual_space.high();
47 _the_space = new TenuredSpace(_bts, MemRegion(bottom, end));
48 _the_space->reset_saved_mark();
49 _shrink_factor = 0;
50 _capacity_at_prologue = 0;
51
52 _gc_stats = new GCStats();
53
54 // initialize performance counters
55
56 const char* gen_name = "old";
57 GenCollectorPolicy* gcp = (GenCollectorPolicy*) GenCollectedHeap::heap()->collector_policy();
58
59 // Generation Counters -- generation 1, 1 subspace
60 _gen_counters = new GenerationCounters(gen_name, 1, 1,
61 gcp->min_old_size(), gcp->max_old_size(), &_virtual_space);
62
63 _gc_counters = new CollectorCounters("MSC", 1);
64
65 _space_counters = new CSpaceCounters(gen_name, 0,
66 _virtual_space.reserved_size(),
67 _the_space, _gen_counters);
68 }
69
70 void TenuredGeneration::gc_prologue(bool full) {
71 _capacity_at_prologue = capacity();
72 _used_at_prologue = used();
73 }
74
75 bool TenuredGeneration::should_collect(bool full,
76 size_t size,
77 bool is_tlab) {
78 // This should be one big conditional or (||), but I want to be able to tell
79 // why it returns what it returns (without re-evaluating the conditionals
80 // in case they aren't idempotent), so I'm doing it this way.
81 // DeMorgan says it's okay.
82 bool result = false;
83 if (!result && full) {
84 result = true;
85 if (PrintGC && Verbose) {
86 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
87 " full");
88 }
89 }
90 if (!result && should_allocate(size, is_tlab)) {
91 result = true;
92 if (PrintGC && Verbose) {
93 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
94 " should_allocate(" SIZE_FORMAT ")",
95 size);
96 }
97 }
98 // If we don't have very much free space.
99 // XXX: 10000 should be a percentage of the capacity!!!
100 if (!result && free() < 10000) {
101 result = true;
102 if (PrintGC && Verbose) {
103 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
104 " free(): " SIZE_FORMAT,
105 free());
106 }
107 }
108 // If we had to expand to accommodate promotions from younger generations
109 if (!result && _capacity_at_prologue < capacity()) {
110 result = true;
111 if (PrintGC && Verbose) {
112 gclog_or_tty->print_cr("TenuredGeneration::should_collect: because"
113 "_capacity_at_prologue: " SIZE_FORMAT " < capacity(): " SIZE_FORMAT,
114 _capacity_at_prologue, capacity());
115 }
116 }
117 return result;
118 }
119
120 void TenuredGeneration::compute_new_size() {
121 assert_locked_or_safepoint(Heap_lock);
122
123 // Compute some numbers about the state of the heap.
124 const size_t used_after_gc = used();
125 const size_t capacity_after_gc = capacity();
126
127 CardGeneration::compute_new_size();
128
129 assert(used() == used_after_gc && used_after_gc <= capacity(),
130 err_msg("used: " SIZE_FORMAT " used_after_gc: " SIZE_FORMAT
131 " capacity: " SIZE_FORMAT, used(), used_after_gc, capacity()));
132 }
133
134 void TenuredGeneration::update_gc_stats(int current_level,
135 bool full) {
136 // If the next lower level(s) has been collected, gather any statistics
137 // that are of interest at this point.
138 if (!full && (current_level + 1) == level()) {
139 // Calculate size of data promoted from the younger generations
140 // before doing the collection.
141 size_t used_before_gc = used();
142
143 // If the younger gen collections were skipped, then the
144 // number of promoted bytes will be 0 and adding it to the
145 // average will incorrectly lessen the average. It is, however,
146 // also possible that no promotion was needed.
147 if (used_before_gc >= _used_at_prologue) {
148 size_t promoted_in_bytes = used_before_gc - _used_at_prologue;
149 gc_stats()->avg_promoted()->sample(promoted_in_bytes);
150 }
151 }
152 }
153
154 void TenuredGeneration::update_counters() {
155 if (UsePerfData) {
156 _space_counters->update_all();
157 _gen_counters->update_all();
158 }
159 }
160
161 bool TenuredGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const {
162 size_t available = max_contiguous_available();
163 size_t av_promo = (size_t)gc_stats()->avg_promoted()->padded_average();
164 bool res = (available >= av_promo) || (available >= max_promotion_in_bytes);
165 if (PrintGC && Verbose) {
166 gclog_or_tty->print_cr(
167 "Tenured: promo attempt is%s safe: available("SIZE_FORMAT") %s av_promo("SIZE_FORMAT"),"
168 "max_promo("SIZE_FORMAT")",
169 res? "":" not", available, res? ">=":"<",
170 av_promo, max_promotion_in_bytes);
171 }
172 return res;
173 }
174
175 void TenuredGeneration::collect(bool full,
176 bool clear_all_soft_refs,
177 size_t size,
178 bool is_tlab) {
179 GenCollectedHeap* gch = GenCollectedHeap::heap();
180
181 SpecializationStats::clear();
182 // Temporarily expand the span of our ref processor, so
183 // refs discovery is over the entire heap, not just this generation
184 ReferenceProcessorSpanMutator
185 x(ref_processor(), gch->reserved_region());
186
187 STWGCTimer* gc_timer = GenMarkSweep::gc_timer();
188 gc_timer->register_gc_start();
189
190 SerialOldTracer* gc_tracer = GenMarkSweep::gc_tracer();
191 gc_tracer->report_gc_start(gch->gc_cause(), gc_timer->gc_start());
192
193 GenMarkSweep::invoke_at_safepoint(_level, ref_processor(), clear_all_soft_refs);
194
195 gc_timer->register_gc_end();
196
197 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
198
199 SpecializationStats::print();
200 }
201
202 HeapWord*
203 TenuredGeneration::expand_and_allocate(size_t word_size,
204 bool is_tlab,
205 bool parallel) {
206 assert(!is_tlab, "TenuredGeneration does not support TLAB allocation");
207 if (parallel) {
208 MutexLocker x(ParGCRareEvent_lock);
209 HeapWord* result = NULL;
210 size_t byte_size = word_size * HeapWordSize;
211 while (true) {
212 expand(byte_size, _min_heap_delta_bytes);
213 if (GCExpandToAllocateDelayMillis > 0) {
214 os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false);
215 }
216 result = _the_space->par_allocate(word_size);
217 if ( result != NULL) {
218 return result;
219 } else {
220 // If there's not enough expansion space available, give up.
221 if (_virtual_space.uncommitted_size() < byte_size) {
222 return NULL;
223 }
224 // else try again
225 }
226 }
227 } else {
228 expand(word_size*HeapWordSize, _min_heap_delta_bytes);
229 return _the_space->allocate(word_size);
230 }
231 }
232
233 bool TenuredGeneration::expand(size_t bytes, size_t expand_bytes) {
234 GCMutexLocker x(ExpandHeap_lock);
235 return CardGeneration::expand(bytes, expand_bytes);
236 }
237
238 size_t TenuredGeneration::unsafe_max_alloc_nogc() const {
239 return _the_space->free();
240 }
241
242 size_t TenuredGeneration::contiguous_available() const {
243 return _the_space->free() + _virtual_space.uncommitted_size();
244 }
245
246 void TenuredGeneration::assert_correct_size_change_locking() {
247 assert_locked_or_safepoint(ExpandHeap_lock);
248 }
249
250 // Currently nothing to do.
251 void TenuredGeneration::prepare_for_verify() {}
252
253 void TenuredGeneration::object_iterate(ObjectClosure* blk) {
254 _the_space->object_iterate(blk);
255 }
256
257 void TenuredGeneration::save_marks() {
258 _the_space->set_saved_mark();
259 }
260
261 void TenuredGeneration::reset_saved_marks() {
262 _the_space->reset_saved_mark();
263 }
264
265 bool TenuredGeneration::no_allocs_since_save_marks() {
266 return _the_space->saved_mark_at_top();
267 }
268
269 #define TenuredGen_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
270 \
271 void TenuredGeneration:: \
272 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \
273 blk->set_generation(this); \
274 _the_space->oop_since_save_marks_iterate##nv_suffix(blk); \
275 blk->reset_generation(); \
276 save_marks(); \
277 }
278
279 ALL_SINCE_SAVE_MARKS_CLOSURES(TenuredGen_SINCE_SAVE_MARKS_ITERATE_DEFN)
280
281 #undef TenuredGen_SINCE_SAVE_MARKS_ITERATE_DEFN
282
283 void TenuredGeneration::gc_epilogue(bool full) {
284 // update the generation and space performance counters
285 update_counters();
286 if (ZapUnusedHeapArea) {
287 _the_space->check_mangled_unused_area_complete();
288 }
289 }
290
291 void TenuredGeneration::record_spaces_top() {
292 assert(ZapUnusedHeapArea, "Not mangling unused space");
293 _the_space->set_top_for_allocations();
294 }
295
296 void TenuredGeneration::verify() {
297 _the_space->verify();
298 }
299
300 void TenuredGeneration::print_on(outputStream* st) const {
301 Generation::print_on(st);
302 st->print(" the");
303 _the_space->print_on(st);
304 }