1 /*
2 * Copyright (c) 2001, 2012, 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 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTG1REFINE_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTG1REFINE_HPP
27
28 #include "memory/allocation.hpp"
29 #include "memory/cardTableModRefBS.hpp"
30 #include "runtime/thread.hpp"
31 #include "utilities/globalDefinitions.hpp"
32
33 // Forward decl
34 class ConcurrentG1RefineThread;
35 class G1RemSet;
36
37 class ConcurrentG1Refine: public CHeapObj<mtGC> {
38 ConcurrentG1RefineThread** _threads;
39 int _n_threads;
40 int _n_worker_threads;
41 /*
42 * The value of the update buffer queue length falls into one of 3 zones:
43 * green, yellow, red. If the value is in [0, green) nothing is
44 * done, the buffers are left unprocessed to enable the caching effect of the
45 * dirtied cards. In the yellow zone [green, yellow) the concurrent refinement
46 * threads are gradually activated. In [yellow, red) all threads are
47 * running. If the length becomes red (max queue length) the mutators start
48 * processing the buffers.
49 *
50 * There are some interesting cases (when G1UseAdaptiveConcRefinement
51 * is turned off):
52 * 1) green = yellow = red = 0. In this case the mutator will process all
53 * buffers. Except for those that are created by the deferred updates
54 * machinery during a collection.
55 * 2) green = 0. Means no caching. Can be a good way to minimize the
56 * amount of time spent updating rsets during a collection.
57 */
58 int _green_zone;
59 int _yellow_zone;
60 int _red_zone;
61
62 int _thread_threshold_step;
63
64 // Reset the threshold step value based of the current zone boundaries.
65 void reset_threshold_step();
66
67 // The cache for card refinement.
68 bool _use_cache;
69 bool _def_use_cache;
70
71 size_t _n_periods; // Used as clearing epoch
72
73 // An evicting cache of the number of times each card
74 // is accessed. Reduces, but does not eliminate, the amount
75 // of duplicated processing of dirty cards.
76
77 enum SomePrivateConstants {
78 epoch_bits = 32,
79 card_num_shift = epoch_bits,
80 epoch_mask = AllBits,
81 card_num_mask = AllBits,
82
83 // The initial cache size is approximately this fraction
84 // of a maximal cache (i.e. the size needed for all cards
85 // in the heap)
86 InitialCacheFraction = 512
87 };
88
89 const static julong card_num_mask_in_place =
90 (julong) card_num_mask << card_num_shift;
91
92 typedef struct {
93 julong _value; // | card_num | epoch |
94 } CardEpochCacheEntry;
95
96 julong make_epoch_entry(unsigned int card_num, unsigned int epoch) {
97 assert(0 <= card_num && card_num < _max_cards, "Bounds");
98 assert(0 <= epoch && epoch <= _n_periods, "must be");
99
100 return ((julong) card_num << card_num_shift) | epoch;
101 }
102
103 unsigned int extract_epoch(julong v) {
104 return (v & epoch_mask);
105 }
106
107 unsigned int extract_card_num(julong v) {
108 return (v & card_num_mask_in_place) >> card_num_shift;
109 }
110
111 typedef struct {
112 unsigned char _count;
113 unsigned char _evict_count;
114 } CardCountCacheEntry;
115
116 CardCountCacheEntry* _card_counts;
117 CardEpochCacheEntry* _card_epochs;
118
119 // The current number of buckets in the card count cache
120 size_t _n_card_counts;
121
122 // The number of cards for the entire reserved heap
123 size_t _max_cards;
124
125 // The max number of buckets for the card counts and epochs caches.
126 // This is the maximum that the counts and epochs will grow to.
127 // It is specified as a fraction or percentage of _max_cards using
128 // G1MaxHotCardCountSizePercent.
129 size_t _max_n_card_counts;
130
131 // Possible sizes of the cache: odd primes that roughly double in size.
132 // (See jvmtiTagMap.cpp).
133 enum {
134 MAX_CC_CACHE_INDEX = 15 // maximum index into the cache size array.
135 };
136
137 static size_t _cc_cache_sizes[MAX_CC_CACHE_INDEX];
138
139 // The index in _cc_cache_sizes corresponding to the size of
140 // _card_counts.
141 int _cache_size_index;
142
143 bool _expand_card_counts;
144
145 const jbyte* _ct_bot;
146
147 jbyte** _hot_cache;
148 int _hot_cache_size;
149 int _n_hot;
150 int _hot_cache_idx;
151
152 int _hot_cache_par_chunk_size;
153 volatile int _hot_cache_par_claimed_idx;
154
155 // Needed to workaround 6817995
156 CardTableModRefBS* _ct_bs;
157 G1CollectedHeap* _g1h;
158
159 // Helper routine for expand_card_count_cache().
160 // The arrays used to hold the card counts and the epochs must have
161 // a 1:1 correspondence. Hence they are allocated and freed together.
162 // Returns true if the allocations of both the counts and epochs
163 // were successful; false otherwise.
164 bool allocate_card_count_cache(size_t n,
165 CardCountCacheEntry** counts,
166 CardEpochCacheEntry** epochs);
167
168 // Expands the arrays that hold the card counts and epochs
169 // to the cache size at index. Returns true if the expansion/
170 // allocation was successful; false otherwise.
171 bool expand_card_count_cache(int index);
172
173 // hash a given key (index of card_ptr) with the specified size
174 static unsigned int hash(size_t key, size_t size) {
175 return (unsigned int) (key % size);
176 }
177
178 // hash a given key (index of card_ptr)
179 unsigned int hash(size_t key) {
180 return hash(key, _n_card_counts);
181 }
182
183 unsigned int ptr_2_card_num(jbyte* card_ptr) {
184 return (unsigned int) (card_ptr - _ct_bot);
185 }
186
187 jbyte* card_num_2_ptr(unsigned int card_num) {
188 return (jbyte*) (_ct_bot + card_num);
189 }
190
191 // Returns the count of this card after incrementing it.
192 jbyte* add_card_count(jbyte* card_ptr, int* count, bool* defer);
193
194 // Returns true if this card is in a young region
195 bool is_young_card(jbyte* card_ptr);
196
197 public:
198 ConcurrentG1Refine();
199 ~ConcurrentG1Refine();
200
201 void init(); // Accomplish some initialization that has to wait.
202 void stop();
203
204 void reinitialize_threads();
205
206 // Iterate over the conc refine threads
207 void threads_do(ThreadClosure *tc);
208
209 // If this is the first entry for the slot, writes into the cache and
210 // returns NULL. If it causes an eviction, returns the evicted pointer.
211 // Otherwise, its a cache hit, and returns NULL.
212 jbyte* cache_insert(jbyte* card_ptr, bool* defer);
213
214 // Process the cached entries.
215 void clean_up_cache(int worker_i, G1RemSet* g1rs, DirtyCardQueue* into_cset_dcq);
216
217 // Set up for parallel processing of the cards in the hot cache
218 void clear_hot_cache_claimed_index() {
219 _hot_cache_par_claimed_idx = 0;
220 }
221
222 // Discard entries in the hot cache.
223 void clear_hot_cache() {
224 _hot_cache_idx = 0; _n_hot = 0;
225 }
226
227 bool hot_cache_is_empty() { return _n_hot == 0; }
228
229 bool use_cache() { return _use_cache; }
230 void set_use_cache(bool b) {
231 if (b) _use_cache = _def_use_cache;
232 else _use_cache = false;
233 }
234
235 void clear_and_record_card_counts();
236
237 static int thread_num();
238
239 void print_worker_threads_on(outputStream* st) const;
240
241 void set_green_zone(int x) { _green_zone = x; }
242 void set_yellow_zone(int x) { _yellow_zone = x; }
243 void set_red_zone(int x) { _red_zone = x; }
244
245 int green_zone() const { return _green_zone; }
246 int yellow_zone() const { return _yellow_zone; }
247 int red_zone() const { return _red_zone; }
248
249 int total_thread_num() const { return _n_threads; }
250 int worker_thread_num() const { return _n_worker_threads; }
251
252 int thread_threshold_step() const { return _thread_threshold_step; }
253 };
254
255 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTG1REFINE_HPP