Mercurial > hg > graal-compiler
annotate src/share/vm/interpreter/oopMapCache.hpp @ 1711:a6bff45449bc
6973570: OrderAccess::storestore() scales poorly on multi-socket x64 and sparc: cache-line ping-ponging
Summary: volatile store to static variable removed in favour of a volatile store to stack to avoid excessive cache coherency traffic; verified that the volatile store is not elided by any of our current compilers.
Reviewed-by: dholmes, dice, jcoomes, kvn
author | ysr |
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date | Tue, 10 Aug 2010 14:53:35 -0700 |
parents | c18cbe5936b8 |
children | f95d63e2154a |
rev | line source |
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0 | 1 /* |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
25 // A Cache for storing (method, bci) -> oopMap. | |
26 // The memory management system uses the cache when locating object | |
27 // references in an interpreted frame. | |
28 // | |
29 // OopMapCache's are allocated lazily per instanceKlass. | |
30 | |
31 // The oopMap (InterpreterOopMap) is stored as a bit mask. If the | |
32 // bit_mask can fit into two words it is stored in | |
33 // the _bit_mask array, otherwise it is allocated on the heap. | |
34 // For OopMapCacheEntry the bit_mask is allocated in the C heap | |
35 // because these entries persist between garbage collections. | |
36 // For InterpreterOopMap the bit_mask is allocated in | |
37 // a resource area for better performance. InterpreterOopMap | |
38 // should only be created and deleted during same garbage collection. | |
39 // | |
40 // If ENABBLE_ZAP_DEAD_LOCALS is defined, two bits are used | |
41 // per entry instead of one. In all cases, | |
42 // the first bit is set to indicate oops as opposed to other | |
43 // values. If the second bit is available, | |
44 // it is set for dead values. We get the following encoding: | |
45 // | |
46 // 00 live value | |
47 // 01 live oop | |
48 // 10 dead value | |
49 // 11 <unused> (we cannot distinguish between dead oops or values with the current oop map generator) | |
50 | |
51 | |
52 class OffsetClosure { | |
53 public: | |
54 virtual void offset_do(int offset) = 0; | |
55 }; | |
56 | |
57 | |
58 class InterpreterOopMap: ResourceObj { | |
59 friend class OopMapCache; | |
60 | |
61 public: | |
62 enum { | |
63 N = 2, // the number of words reserved | |
64 // for inlined mask storage | |
65 small_mask_limit = N * BitsPerWord, // the maximum number of bits | |
66 // available for small masks, | |
67 // small_mask_limit can be set to 0 | |
68 // for testing bit_mask allocation | |
69 | |
70 #ifdef ENABLE_ZAP_DEAD_LOCALS | |
71 bits_per_entry = 2, | |
72 dead_bit_number = 1, | |
73 #else | |
74 bits_per_entry = 1, | |
75 #endif | |
76 oop_bit_number = 0 | |
77 }; | |
78 | |
79 private: | |
80 methodOop _method; // the method for which the mask is valid | |
81 unsigned short _bci; // the bci for which the mask is valid | |
82 int _mask_size; // the mask size in bits | |
83 int _expression_stack_size; // the size of the expression stack in slots | |
84 | |
85 protected: | |
86 intptr_t _bit_mask[N]; // the bit mask if | |
87 // mask_size <= small_mask_limit, | |
88 // ptr to bit mask otherwise | |
89 // "protected" so that sub classes can | |
90 // access it without using trickery in | |
91 // methd bit_mask(). | |
92 #ifdef ASSERT | |
93 bool _resource_allocate_bit_mask; | |
94 #endif | |
95 | |
96 // access methods | |
97 methodOop method() const { return _method; } | |
98 void set_method(methodOop v) { _method = v; } | |
99 int bci() const { return _bci; } | |
100 void set_bci(int v) { _bci = v; } | |
101 int mask_size() const { return _mask_size; } | |
102 void set_mask_size(int v) { _mask_size = v; } | |
103 int number_of_entries() const { return mask_size() / bits_per_entry; } | |
104 // Test bit mask size and return either the in-line bit mask or allocated | |
105 // bit mask. | |
106 uintptr_t* bit_mask() { return (uintptr_t*)(mask_size() <= small_mask_limit ? (intptr_t)_bit_mask : _bit_mask[0]); } | |
107 | |
108 // return the word size of_bit_mask. mask_size() <= 4 * MAX_USHORT | |
109 size_t mask_word_size() { | |
110 return (mask_size() + BitsPerWord - 1) / BitsPerWord; | |
111 } | |
112 | |
113 uintptr_t entry_at(int offset) { int i = offset * bits_per_entry; return bit_mask()[i / BitsPerWord] >> (i % BitsPerWord); } | |
114 | |
115 void set_expression_stack_size(int sz) { _expression_stack_size = sz; } | |
116 | |
117 #ifdef ENABLE_ZAP_DEAD_LOCALS | |
118 bool is_dead(int offset) { return (entry_at(offset) & (1 << dead_bit_number)) != 0; } | |
119 #endif | |
120 | |
121 // Lookup | |
122 bool match(methodHandle method, int bci) { return _method == method() && _bci == bci; } | |
123 bool is_empty(); | |
124 | |
125 // Initialization | |
126 void initialize(); | |
127 | |
128 public: | |
129 InterpreterOopMap(); | |
130 ~InterpreterOopMap(); | |
131 | |
132 // Copy the OopMapCacheEntry in parameter "from" into this | |
133 // InterpreterOopMap. If the _bit_mask[0] in "from" points to | |
134 // allocated space (i.e., the bit mask was to large to hold | |
135 // in-line), allocate the space from a Resource area. | |
136 void resource_copy(OopMapCacheEntry* from); | |
137 | |
138 void iterate_oop(OffsetClosure* oop_closure); | |
139 void oop_iterate(OopClosure * blk); | |
140 void oop_iterate(OopClosure * blk, MemRegion mr); | |
141 void verify(); | |
142 void print(); | |
143 | |
144 bool is_oop (int offset) { return (entry_at(offset) & (1 << oop_bit_number )) != 0; } | |
145 | |
146 int expression_stack_size() { return _expression_stack_size; } | |
147 | |
148 #ifdef ENABLE_ZAP_DEAD_LOCALS | |
149 void iterate_all(OffsetClosure* oop_closure, OffsetClosure* value_closure, OffsetClosure* dead_closure); | |
150 #endif | |
151 }; | |
152 | |
153 class OopMapCache : public CHeapObj { | |
154 private: | |
155 enum { _size = 32, // Use fixed size for now | |
156 _probe_depth = 3 // probe depth in case of collisions | |
157 }; | |
158 | |
159 OopMapCacheEntry* _array; | |
160 | |
161 unsigned int hash_value_for(methodHandle method, int bci); | |
162 OopMapCacheEntry* entry_at(int i) const; | |
163 | |
164 Mutex _mut; | |
165 | |
166 void flush(); | |
167 | |
168 public: | |
169 OopMapCache(); | |
170 ~OopMapCache(); // free up memory | |
171 | |
172 // flush cache entry is occupied by an obsolete method | |
173 void flush_obsolete_entries(); | |
174 | |
175 // Returns the oopMap for (method, bci) in parameter "entry". | |
176 // Returns false if an oop map was not found. | |
177 void lookup(methodHandle method, int bci, InterpreterOopMap* entry); | |
178 | |
179 // Compute an oop map without updating the cache or grabbing any locks (for debugging) | |
180 static void compute_one_oop_map(methodHandle method, int bci, InterpreterOopMap* entry); | |
181 | |
182 // Helpers | |
183 // Iterate over the entries in the cached OopMapCacheEntry's | |
184 void oop_iterate(OopClosure *blk); | |
185 void oop_iterate(OopClosure *blk, MemRegion mr); | |
186 void verify(); | |
187 | |
188 // Returns total no. of bytes allocated as part of OopMapCache's | |
189 static long memory_usage() PRODUCT_RETURN0; | |
190 }; |