1 /*
2 * Copyright (c) 2001, 2019, 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 size_t min_byte_size,
49 size_t max_byte_size,
50 CardTableRS* remset) :
51 CardGeneration(rs, initial_byte_size, remset)
52 {
53 HeapWord* bottom = (HeapWord*) _virtual_space.low();
54 HeapWord* end = (HeapWord*) _virtual_space.high();
55 _the_space = new TenuredSpace(_bts, MemRegion(bottom, end));
56 _the_space->reset_saved_mark();
57 _shrink_factor = 0;
58 _capacity_at_prologue = 0;
59
60 _gc_stats = new GCStats();
61
62 // initialize performance counters
63
64 const char* gen_name = "old";
65 // Generation Counters -- generation 1, 1 subspace
66 _gen_counters = new GenerationCounters(gen_name, 1, 1,
67 min_byte_size, max_byte_size, &_virtual_space);
68
69 _gc_counters = new CollectorCounters("Serial full collection pauses", 1);
70
71 _space_counters = new CSpaceCounters(gen_name, 0,
72 _virtual_space.reserved_size(),
73 _the_space, _gen_counters);
74 }
75
76 void TenuredGeneration::gc_prologue(bool full) {
77 _capacity_at_prologue = capacity();
78 _used_at_prologue = used();
79 }
80
81 bool TenuredGeneration::should_collect(bool full,
82 size_t size,
83 bool is_tlab) {
84 // This should be one big conditional or (||), but I want to be able to tell
85 // why it returns what it returns (without re-evaluating the conditionals
86 // in case they aren't idempotent), so I'm doing it this way.
87 // DeMorgan says it's okay.
88 if (full) {
89 log_trace(gc)("TenuredGeneration::should_collect: because full");
90 return true;
91 }
92 if (should_allocate(size, is_tlab)) {
93 log_trace(gc)("TenuredGeneration::should_collect: because should_allocate(" SIZE_FORMAT ")", size);
94 return true;
95 }
96 // If we don't have very much free space.
97 // XXX: 10000 should be a percentage of the capacity!!!
98 if (free() < 10000) {
99 log_trace(gc)("TenuredGeneration::should_collect: because free(): " SIZE_FORMAT, free());
100 return true;
101 }
102 // If we had to expand to accommodate promotions from the young generation
103 if (_capacity_at_prologue < capacity()) {
104 log_trace(gc)("TenuredGeneration::should_collect: because_capacity_at_prologue: " SIZE_FORMAT " < capacity(): " SIZE_FORMAT,
105 _capacity_at_prologue, capacity());
106 return true;
107 }
108
109 return false;
110 }
111
112 void TenuredGeneration::compute_new_size() {
113 assert_locked_or_safepoint(Heap_lock);
114
115 // Compute some numbers about the state of the heap.
116 const size_t used_after_gc = used();
117 const size_t capacity_after_gc = capacity();
118
119 CardGeneration::compute_new_size();
120
121 assert(used() == used_after_gc && used_after_gc <= capacity(),
122 "used: " SIZE_FORMAT " used_after_gc: " SIZE_FORMAT
123 " capacity: " SIZE_FORMAT, used(), used_after_gc, capacity());
124 }
125
126 void TenuredGeneration::update_gc_stats(Generation* current_generation,
127 bool full) {
128 // If the young generation has been collected, gather any statistics
129 // that are of interest at this point.
130 bool current_is_young = GenCollectedHeap::heap()->is_young_gen(current_generation);
131 if (!full && current_is_young) {
132 // Calculate size of data promoted from the young generation
133 // before doing the collection.
134 size_t used_before_gc = used();
135
136 // If the young gen collection was skipped, then the
137 // number of promoted bytes will be 0 and adding it to the
138 // average will incorrectly lessen the average. It is, however,
139 // also possible that no promotion was needed.
140 if (used_before_gc >= _used_at_prologue) {
141 size_t promoted_in_bytes = used_before_gc - _used_at_prologue;
142 gc_stats()->avg_promoted()->sample(promoted_in_bytes);
143 }
144 }
145 }
146
147 void TenuredGeneration::update_counters() {
148 if (UsePerfData) {
149 _space_counters->update_all();
150 _gen_counters->update_all();
151 }
152 }
153
154 bool TenuredGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const {
155 size_t available = max_contiguous_available();
156 size_t av_promo = (size_t)gc_stats()->avg_promoted()->padded_average();
157 bool res = (available >= av_promo) || (available >= max_promotion_in_bytes);
158
159 log_trace(gc)("Tenured: promo attempt is%s safe: available(" SIZE_FORMAT ") %s av_promo(" SIZE_FORMAT "), max_promo(" SIZE_FORMAT ")",
160 res? "":" not", available, res? ">=":"<", av_promo, max_promotion_in_bytes);
161
162 return res;
163 }
164
165 void TenuredGeneration::collect(bool full,
166 bool clear_all_soft_refs,
167 size_t size,
168 bool is_tlab) {
169 GenCollectedHeap* gch = GenCollectedHeap::heap();
170
171 // Temporarily expand the span of our ref processor, so
172 // refs discovery is over the entire heap, not just this generation
173 ReferenceProcessorSpanMutator
174 x(ref_processor(), gch->reserved_region());
175
176 STWGCTimer* gc_timer = GenMarkSweep::gc_timer();
177 gc_timer->register_gc_start();
178
179 SerialOldTracer* gc_tracer = GenMarkSweep::gc_tracer();
180 gc_tracer->report_gc_start(gch->gc_cause(), gc_timer->gc_start());
181
182 gch->pre_full_gc_dump(gc_timer);
183
184 GenMarkSweep::invoke_at_safepoint(ref_processor(), clear_all_soft_refs);
185
186 gch->post_full_gc_dump(gc_timer);
187
188 gc_timer->register_gc_end();
189
190 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
191 }
192
193 HeapWord*
194 TenuredGeneration::expand_and_allocate(size_t word_size,
195 bool is_tlab,
196 bool parallel) {
197 assert(!is_tlab, "TenuredGeneration does not support TLAB allocation");
198 if (parallel) {
199 MutexLocker x(ParGCRareEvent_lock);
200 HeapWord* result = NULL;
201 size_t byte_size = word_size * HeapWordSize;
202 while (true) {
203 expand(byte_size, _min_heap_delta_bytes);
204 if (GCExpandToAllocateDelayMillis > 0) {
205 os::naked_sleep(GCExpandToAllocateDelayMillis);
206 }
207 result = _the_space->par_allocate(word_size);
208 if ( result != NULL) {
209 return result;
210 } else {
211 // If there's not enough expansion space available, give up.
212 if (_virtual_space.uncommitted_size() < byte_size) {
213 return NULL;
214 }
215 // else try again
216 }
217 }
218 } else {
219 expand(word_size*HeapWordSize, _min_heap_delta_bytes);
220 return _the_space->allocate(word_size);
221 }
222 }
223
224 bool TenuredGeneration::expand(size_t bytes, size_t expand_bytes) {
225 GCMutexLocker x(ExpandHeap_lock);
226 return CardGeneration::expand(bytes, expand_bytes);
227 }
228
229 size_t TenuredGeneration::unsafe_max_alloc_nogc() const {
230 return _the_space->free();
231 }
232
233 size_t TenuredGeneration::contiguous_available() const {
234 return _the_space->free() + _virtual_space.uncommitted_size();
235 }
236
237 void TenuredGeneration::assert_correct_size_change_locking() {
238 assert_locked_or_safepoint(ExpandHeap_lock);
239 }
240
241 // Currently nothing to do.
242 void TenuredGeneration::prepare_for_verify() {}
243
244 void TenuredGeneration::object_iterate(ObjectClosure* blk) {
245 _the_space->object_iterate(blk);
246 }
247
248 void TenuredGeneration::save_marks() {
249 _the_space->set_saved_mark();
250 }
251
252 void TenuredGeneration::reset_saved_marks() {
253 _the_space->reset_saved_mark();
254 }
255
256 bool TenuredGeneration::no_allocs_since_save_marks() {
257 return _the_space->saved_mark_at_top();
258 }
259
260 void TenuredGeneration::gc_epilogue(bool full) {
261 // update the generation and space performance counters
262 update_counters();
263 if (ZapUnusedHeapArea) {
264 _the_space->check_mangled_unused_area_complete();
265 }
266 }
267
268 void TenuredGeneration::record_spaces_top() {
269 assert(ZapUnusedHeapArea, "Not mangling unused space");
270 _the_space->set_top_for_allocations();
271 }
272
273 void TenuredGeneration::verify() {
274 _the_space->verify();
275 }
276
277 void TenuredGeneration::print_on(outputStream* st) const {
278 Generation::print_on(st);
279 st->print(" the");
280 _the_space->print_on(st);
281 }