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