tenuredGeneration.cpp revision 9727:f944761a3ce3 
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/genOopClosures.inline.hpp"
33#include "gc/shared/generationSpec.hpp"
34#include "gc/shared/space.hpp"
35#include "logging/log.hpp"
36#include "memory/allocation.inline.hpp"
37#include "oops/oop.inline.hpp"
38#include "runtime/java.hpp"
39#include "utilities/macros.hpp"
40#if INCLUDE_ALL_GCS
41#include "gc/cms/parOopClosures.hpp"
42#endif
43
44TenuredGeneration::TenuredGeneration(ReservedSpace rs,
45                                     size_t initial_byte_size,
46                                     CardTableRS* remset) :
47  CardGeneration(rs, initial_byte_size, remset)
48{
49  HeapWord* bottom = (HeapWord*) _virtual_space.low();
50  HeapWord* end    = (HeapWord*) _virtual_space.high();
51  _the_space  = new TenuredSpace(_bts, MemRegion(bottom, end));
52  _the_space->reset_saved_mark();
53  _shrink_factor = 0;
54  _capacity_at_prologue = 0;
55
56  _gc_stats = new GCStats();
57
58  // initialize performance counters
59
60  const char* gen_name = "old";
61  GenCollectorPolicy* gcp = GenCollectedHeap::heap()->gen_policy();
62  // Generation Counters -- generation 1, 1 subspace
63  _gen_counters = new GenerationCounters(gen_name, 1, 1,
64      gcp->min_old_size(), gcp->max_old_size(), &_virtual_space);
65
66  _gc_counters = new CollectorCounters("MSC", 1);
67
68  _space_counters = new CSpaceCounters(gen_name, 0,
69                                       _virtual_space.reserved_size(),
70                                       _the_space, _gen_counters);
71}
72
73void TenuredGeneration::gc_prologue(bool full) {
74  _capacity_at_prologue = capacity();
75  _used_at_prologue = used();
76}
77
78bool TenuredGeneration::should_collect(bool  full,
79                                       size_t size,
80                                       bool   is_tlab) {
81  // This should be one big conditional or (||), but I want to be able to tell
82  // why it returns what it returns (without re-evaluating the conditionals
83  // in case they aren't idempotent), so I'm doing it this way.
84  // DeMorgan says it's okay.
85  if (full) {
86    log_trace(gc)("TenuredGeneration::should_collect: because full");
87    return true;
88  }
89  if (should_allocate(size, is_tlab)) {
90    log_trace(gc)("TenuredGeneration::should_collect: because should_allocate(" SIZE_FORMAT ")", size);
91    return true;
92  }
93  // If we don't have very much free space.
94  // XXX: 10000 should be a percentage of the capacity!!!
95  if (free() < 10000) {
96    log_trace(gc)("TenuredGeneration::should_collect: because free(): " SIZE_FORMAT, free());
97    return true;
98  }
99  // If we had to expand to accommodate promotions from the young generation
100  if (_capacity_at_prologue < capacity()) {
101    log_trace(gc)("TenuredGeneration::should_collect: because_capacity_at_prologue: " SIZE_FORMAT " < capacity(): " SIZE_FORMAT,
102        _capacity_at_prologue, capacity());
103    return true;
104  }
105
106  return false;
107}
108
109void TenuredGeneration::compute_new_size() {
110  assert_locked_or_safepoint(Heap_lock);
111
112  // Compute some numbers about the state of the heap.
113  const size_t used_after_gc = used();
114  const size_t capacity_after_gc = capacity();
115
116  CardGeneration::compute_new_size();
117
118  assert(used() == used_after_gc && used_after_gc <= capacity(),
119         "used: " SIZE_FORMAT " used_after_gc: " SIZE_FORMAT
120         " capacity: " SIZE_FORMAT, used(), used_after_gc, capacity());
121}
122
123void TenuredGeneration::update_gc_stats(Generation* current_generation,
124                                        bool full) {
125  // If the young generation has been collected, gather any statistics
126  // that are of interest at this point.
127  bool current_is_young = GenCollectedHeap::heap()->is_young_gen(current_generation);
128  if (!full && current_is_young) {
129    // Calculate size of data promoted from the young generation
130    // before doing the collection.
131    size_t used_before_gc = used();
132
133    // If the young gen collection was skipped, then the
134    // number of promoted bytes will be 0 and adding it to the
135    // average will incorrectly lessen the average.  It is, however,
136    // also possible that no promotion was needed.
137    if (used_before_gc >= _used_at_prologue) {
138      size_t promoted_in_bytes = used_before_gc - _used_at_prologue;
139      gc_stats()->avg_promoted()->sample(promoted_in_bytes);
140    }
141  }
142}
143
144void TenuredGeneration::update_counters() {
145  if (UsePerfData) {
146    _space_counters->update_all();
147    _gen_counters->update_all();
148  }
149}
150
151bool TenuredGeneration::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const {
152  size_t available = max_contiguous_available();
153  size_t av_promo  = (size_t)gc_stats()->avg_promoted()->padded_average();
154  bool   res = (available >= av_promo) || (available >= max_promotion_in_bytes);
155
156  log_trace(gc)("Tenured: promo attempt is%s safe: available(" SIZE_FORMAT ") %s av_promo(" SIZE_FORMAT "), max_promo(" SIZE_FORMAT ")",
157    res? "":" not", available, res? ">=":"<", av_promo, max_promotion_in_bytes);
158
159  return res;
160}
161
162void TenuredGeneration::collect(bool   full,
163                                bool   clear_all_soft_refs,
164                                size_t size,
165                                bool   is_tlab) {
166  GenCollectedHeap* gch = GenCollectedHeap::heap();
167
168  // Temporarily expand the span of our ref processor, so
169  // refs discovery is over the entire heap, not just this generation
170  ReferenceProcessorSpanMutator
171    x(ref_processor(), gch->reserved_region());
172
173  STWGCTimer* gc_timer = GenMarkSweep::gc_timer();
174  gc_timer->register_gc_start();
175
176  SerialOldTracer* gc_tracer = GenMarkSweep::gc_tracer();
177  gc_tracer->report_gc_start(gch->gc_cause(), gc_timer->gc_start());
178
179  GenMarkSweep::invoke_at_safepoint(ref_processor(), clear_all_soft_refs);
180
181  gc_timer->register_gc_end();
182
183  gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
184}
185
186HeapWord*
187TenuredGeneration::expand_and_allocate(size_t word_size,
188                                       bool is_tlab,
189                                       bool parallel) {
190  assert(!is_tlab, "TenuredGeneration does not support TLAB allocation");
191  if (parallel) {
192    MutexLocker x(ParGCRareEvent_lock);
193    HeapWord* result = NULL;
194    size_t byte_size = word_size * HeapWordSize;
195    while (true) {
196      expand(byte_size, _min_heap_delta_bytes);
197      if (GCExpandToAllocateDelayMillis > 0) {
198        os::sleep(Thread::current(), GCExpandToAllocateDelayMillis, false);
199      }
200      result = _the_space->par_allocate(word_size);
201      if ( result != NULL) {
202        return result;
203      } else {
204        // If there's not enough expansion space available, give up.
205        if (_virtual_space.uncommitted_size() < byte_size) {
206          return NULL;
207        }
208        // else try again
209      }
210    }
211  } else {
212    expand(word_size*HeapWordSize, _min_heap_delta_bytes);
213    return _the_space->allocate(word_size);
214  }
215}
216
217bool TenuredGeneration::expand(size_t bytes, size_t expand_bytes) {
218  GCMutexLocker x(ExpandHeap_lock);
219  return CardGeneration::expand(bytes, expand_bytes);
220}
221
222size_t TenuredGeneration::unsafe_max_alloc_nogc() const {
223  return _the_space->free();
224}
225
226size_t TenuredGeneration::contiguous_available() const {
227  return _the_space->free() + _virtual_space.uncommitted_size();
228}
229
230void TenuredGeneration::assert_correct_size_change_locking() {
231  assert_locked_or_safepoint(ExpandHeap_lock);
232}
233
234// Currently nothing to do.
235void TenuredGeneration::prepare_for_verify() {}
236
237void TenuredGeneration::object_iterate(ObjectClosure* blk) {
238  _the_space->object_iterate(blk);
239}
240
241void TenuredGeneration::save_marks() {
242  _the_space->set_saved_mark();
243}
244
245void TenuredGeneration::reset_saved_marks() {
246  _the_space->reset_saved_mark();
247}
248
249bool TenuredGeneration::no_allocs_since_save_marks() {
250  return _the_space->saved_mark_at_top();
251}
252
253#define TenuredGen_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix)     \
254                                                                                \
255void TenuredGeneration::                                                        \
256oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) {                  \
257  blk->set_generation(this);                                                    \
258  _the_space->oop_since_save_marks_iterate##nv_suffix(blk);                     \
259  blk->reset_generation();                                                      \
260  save_marks();                                                                 \
261}
262
263ALL_SINCE_SAVE_MARKS_CLOSURES(TenuredGen_SINCE_SAVE_MARKS_ITERATE_DEFN)
264
265#undef TenuredGen_SINCE_SAVE_MARKS_ITERATE_DEFN
266
267void TenuredGeneration::gc_epilogue(bool full) {
268  // update the generation and space performance counters
269  update_counters();
270  if (ZapUnusedHeapArea) {
271    _the_space->check_mangled_unused_area_complete();
272  }
273}
274
275void TenuredGeneration::record_spaces_top() {
276  assert(ZapUnusedHeapArea, "Not mangling unused space");
277  _the_space->set_top_for_allocations();
278}
279
280void TenuredGeneration::verify() {
281  _the_space->verify();
282}
283
284void TenuredGeneration::print_on(outputStream* st)  const {
285  Generation::print_on(st);
286  st->print("   the");
287  _the_space->print_on(st);
288}
289