28 #include "gc_implementation/shared/gcUtil.hpp"
29 #include "memory/allocation.hpp"
30 #include "runtime/atomic.hpp"
31 #include "utilities/globalDefinitions.hpp"
32
33 // Forward declarations.
34 class PLABStats;
35
36 // A per-thread allocation buffer used during GC.
37 class PLAB: public CHeapObj<mtGC> {
38 protected:
39 char head[32];
40 size_t _word_sz; // In HeapWord units
41 HeapWord* _bottom;
42 HeapWord* _top;
43 HeapWord* _end; // Last allocatable address + 1
44 HeapWord* _hard_end; // _end + AlignmentReserve
45 // In support of ergonomic sizing of PLAB's
46 size_t _allocated; // in HeapWord units
47 size_t _wasted; // in HeapWord units
48 char tail[32];
49 static size_t AlignmentReserve;
50
51 // Force future allocations to fail and queries for contains()
52 // to return false. Returns the amount of unused space in this PLAB.
53 size_t invalidate() {
54 _end = _hard_end;
55 size_t remaining = pointer_delta(_end, _top); // Calculate remaining space.
56 _top = _end; // Force future allocations to fail.
57 _bottom = _end; // Force future contains() queries to return false.
58 return remaining;
59 }
60
61 // Fill in remaining space with a dummy object and invalidate the PLAB. Returns
62 // the amount of remaining space.
63 size_t retire_internal();
64
65 public:
66 // Initializes the buffer to be empty, but with the given "word_sz".
67 // Must get initialized with "set_buf" for an allocation to succeed.
68 PLAB(size_t word_sz);
69 virtual ~PLAB() {}
70
71 // Minimum PLAB size.
72 static size_t min_size();
73 // Maximum PLAB size.
74 static size_t max_size();
75
76 // If an allocation of the given "word_sz" can be satisfied within the
77 // buffer, do the allocation, returning a pointer to the start of the
78 // allocated block. If the allocation request cannot be satisfied,
79 // return NULL.
80 HeapWord* allocate(size_t word_sz) {
81 HeapWord* res = _top;
82 if (pointer_delta(_end, _top) >= word_sz) {
83 _top = _top + word_sz;
84 return res;
85 } else {
86 return NULL;
87 }
88 }
89
90 // Allocate the object aligned to "alignment_in_bytes".
91 HeapWord* allocate_aligned(size_t word_sz, unsigned short alignment_in_bytes);
92
93 // Undo the last allocation in the buffer, which is required to be of the
94 // "obj" of the given "word_sz".
95 void undo_allocation(HeapWord* obj, size_t word_sz) {
96 assert(pointer_delta(_top, _bottom) >= word_sz, "Bad undo");
97 assert(pointer_delta(_top, obj) == word_sz, "Bad undo");
98 _top = obj;
99 }
100
101 // The total (word) size of the buffer, including both allocated and
102 // unallocated space.
103 size_t word_sz() { return _word_sz; }
104
105 // Should only be done if we are about to reset with a new buffer of the
106 // given size.
107 void set_word_size(size_t new_word_sz) {
108 assert(new_word_sz > AlignmentReserve, "Too small");
109 _word_sz = new_word_sz;
110 }
111
112 // The number of words of unallocated space remaining in the buffer.
113 size_t words_remaining() {
114 assert(_end >= _top, "Negative buffer");
115 return pointer_delta(_end, _top, HeapWordSize);
116 }
117
118 bool contains(void* addr) {
119 return (void*)_bottom <= addr && addr < (void*)_hard_end;
120 }
121
122 // Sets the space of the buffer to be [buf, space+word_sz()).
123 virtual void set_buf(HeapWord* buf) {
124 _bottom = buf;
129 // In support of ergonomic sizing
130 _allocated += word_sz();
131 }
132
133 // Flush allocation statistics into the given PLABStats supporting ergonomic
134 // sizing of PLAB's and retire the current buffer. To be called at the end of
135 // GC.
136 void flush_and_retire_stats(PLABStats* stats);
137
138 // Fills in the unallocated portion of the buffer with a garbage object and updates
139 // statistics. To be called during GC.
140 virtual void retire();
141
142 void print() PRODUCT_RETURN;
143 };
144
145 // PLAB book-keeping.
146 class PLABStats VALUE_OBJ_CLASS_SPEC {
147 size_t _allocated; // Total allocated
148 size_t _wasted; // of which wasted (internal fragmentation)
149 size_t _unused; // Unused in last buffer
150 size_t _desired_plab_sz;// Output of filter (below), suitably trimmed and quantized
151 AdaptiveWeightedAverage
152 _filter; // Integrator with decay
153
154 void reset() {
155 _allocated = 0;
156 _wasted = 0;
157 _unused = 0;
158 }
159 public:
160 PLABStats(size_t desired_plab_sz_, unsigned wt) :
161 _allocated(0),
162 _wasted(0),
163 _unused(0),
164 _desired_plab_sz(desired_plab_sz_),
165 _filter(wt)
166 { }
167
168 static const size_t min_size() {
169 return PLAB::min_size();
170 }
171
172 static const size_t max_size() {
173 return PLAB::max_size();
174 }
175
176 size_t desired_plab_sz() {
177 return _desired_plab_sz;
178 }
179
180 // Updates the current desired PLAB size. Computes the new desired PLAB size,
181 // updates _desired_plab_sz and clears sensor accumulators.
182 void adjust_desired_plab_sz(uint no_of_gc_workers);
183
184 void add_allocated(size_t v) {
185 Atomic::add_ptr(v, &_allocated);
186 }
187
188 void add_unused(size_t v) {
189 Atomic::add_ptr(v, &_unused);
190 }
191
192 void add_wasted(size_t v) {
193 Atomic::add_ptr(v, &_wasted);
194 }
195 };
196
197 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_PLAB_HPP
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28 #include "gc_implementation/shared/gcUtil.hpp"
29 #include "memory/allocation.hpp"
30 #include "runtime/atomic.hpp"
31 #include "utilities/globalDefinitions.hpp"
32
33 // Forward declarations.
34 class PLABStats;
35
36 // A per-thread allocation buffer used during GC.
37 class PLAB: public CHeapObj<mtGC> {
38 protected:
39 char head[32];
40 size_t _word_sz; // In HeapWord units
41 HeapWord* _bottom;
42 HeapWord* _top;
43 HeapWord* _end; // Last allocatable address + 1
44 HeapWord* _hard_end; // _end + AlignmentReserve
45 // In support of ergonomic sizing of PLAB's
46 size_t _allocated; // in HeapWord units
47 size_t _wasted; // in HeapWord units
48 size_t _undo_wasted;
49 char tail[32];
50 static size_t AlignmentReserve;
51
52 // Force future allocations to fail and queries for contains()
53 // to return false. Returns the amount of unused space in this PLAB.
54 size_t invalidate() {
55 _end = _hard_end;
56 size_t remaining = pointer_delta(_end, _top); // Calculate remaining space.
57 _top = _end; // Force future allocations to fail.
58 _bottom = _end; // Force future contains() queries to return false.
59 return remaining;
60 }
61
62 // Fill in remaining space with a dummy object and invalidate the PLAB. Returns
63 // the amount of remaining space.
64 size_t retire_internal();
65
66 void add_undo_waste(HeapWord* obj, size_t word_sz);
67
68 // Undo the last allocation in the buffer, which is required to be of the
69 // "obj" of the given "word_sz".
70 void undo_last_allocation(HeapWord* obj, size_t word_sz);
71
72 public:
73 // Initializes the buffer to be empty, but with the given "word_sz".
74 // Must get initialized with "set_buf" for an allocation to succeed.
75 PLAB(size_t word_sz);
76 virtual ~PLAB() {}
77
78 // Minimum PLAB size.
79 static size_t min_size();
80 // Maximum PLAB size.
81 static size_t max_size();
82
83 // If an allocation of the given "word_sz" can be satisfied within the
84 // buffer, do the allocation, returning a pointer to the start of the
85 // allocated block. If the allocation request cannot be satisfied,
86 // return NULL.
87 HeapWord* allocate(size_t word_sz) {
88 HeapWord* res = _top;
89 if (pointer_delta(_end, _top) >= word_sz) {
90 _top = _top + word_sz;
91 return res;
92 } else {
93 return NULL;
94 }
95 }
96
97 // Allocate the object aligned to "alignment_in_bytes".
98 HeapWord* allocate_aligned(size_t word_sz, unsigned short alignment_in_bytes);
99
100 // Undo any allocation in the buffer, which is required to be of the
101 // "obj" of the given "word_sz".
102 void undo_allocation(HeapWord* obj, size_t word_sz);
103
104 // The total (word) size of the buffer, including both allocated and
105 // unallocated space.
106 size_t word_sz() { return _word_sz; }
107
108 size_t waste() { return _wasted; }
109 size_t undo_waste() { return _undo_wasted; }
110
111 // Should only be done if we are about to reset with a new buffer of the
112 // given size.
113 void set_word_size(size_t new_word_sz) {
114 assert(new_word_sz > AlignmentReserve, "Too small");
115 _word_sz = new_word_sz;
116 }
117
118 // The number of words of unallocated space remaining in the buffer.
119 size_t words_remaining() {
120 assert(_end >= _top, "Negative buffer");
121 return pointer_delta(_end, _top, HeapWordSize);
122 }
123
124 bool contains(void* addr) {
125 return (void*)_bottom <= addr && addr < (void*)_hard_end;
126 }
127
128 // Sets the space of the buffer to be [buf, space+word_sz()).
129 virtual void set_buf(HeapWord* buf) {
130 _bottom = buf;
135 // In support of ergonomic sizing
136 _allocated += word_sz();
137 }
138
139 // Flush allocation statistics into the given PLABStats supporting ergonomic
140 // sizing of PLAB's and retire the current buffer. To be called at the end of
141 // GC.
142 void flush_and_retire_stats(PLABStats* stats);
143
144 // Fills in the unallocated portion of the buffer with a garbage object and updates
145 // statistics. To be called during GC.
146 virtual void retire();
147
148 void print() PRODUCT_RETURN;
149 };
150
151 // PLAB book-keeping.
152 class PLABStats VALUE_OBJ_CLASS_SPEC {
153 size_t _allocated; // Total allocated
154 size_t _wasted; // of which wasted (internal fragmentation)
155 size_t _undo_wasted; // of which wasted on undo (is not used for calculation of PLAB size)
156 size_t _unused; // Unused in last buffer
157 size_t _desired_plab_sz;// Output of filter (below), suitably trimmed and quantized
158 AdaptiveWeightedAverage
159 _filter; // Integrator with decay
160
161 void reset() {
162 _allocated = 0;
163 _wasted = 0;
164 _undo_wasted = 0;
165 _unused = 0;
166 }
167 public:
168 PLABStats(size_t desired_plab_sz_, unsigned wt) :
169 _allocated(0),
170 _wasted(0),
171 _undo_wasted(0),
172 _unused(0),
173 _desired_plab_sz(desired_plab_sz_),
174 _filter(wt)
175 { }
176
177 static const size_t min_size() {
178 return PLAB::min_size();
179 }
180
181 static const size_t max_size() {
182 return PLAB::max_size();
183 }
184
185 size_t desired_plab_sz() {
186 return _desired_plab_sz;
187 }
188
189 // Updates the current desired PLAB size. Computes the new desired PLAB size,
190 // updates _desired_plab_sz and clears sensor accumulators.
191 void adjust_desired_plab_sz(uint no_of_gc_workers);
192
193 void add_allocated(size_t v) {
194 Atomic::add_ptr(v, &_allocated);
195 }
196
197 void add_unused(size_t v) {
198 Atomic::add_ptr(v, &_unused);
199 }
200
201 void add_wasted(size_t v) {
202 Atomic::add_ptr(v, &_wasted);
203 }
204
205 void add_undo_wasted(size_t v) {
206 Atomic::add_ptr(v, &_undo_wasted);
207 }
208 };
209
210 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_PLAB_HPP
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