1 /*
2 * Copyright (c) 2001, 2013, 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_PARNEW_PARGCALLOCBUFFER_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_PARNEW_PARGCALLOCBUFFER_HPP
27
28 #include "memory/allocation.hpp"
29 #include "memory/blockOffsetTable.hpp"
30 #include "memory/threadLocalAllocBuffer.hpp"
31 #include "utilities/globalDefinitions.hpp"
32
33 // Forward decl.
34
35 class PLABStats;
36
37 // A per-thread allocation buffer used during GC.
38 class ParGCAllocBuffer: public CHeapObj<mtGC> {
39 protected:
40 char head[32];
41 size_t _word_sz; // in HeapWord units
42 HeapWord* _bottom;
43 HeapWord* _top;
44 HeapWord* _end; // last allocatable address + 1
45 HeapWord* _hard_end; // _end + AlignmentReserve
46 bool _retained; // whether we hold a _retained_filler
47 MemRegion _retained_filler;
48 // In support of ergonomic sizing of PLAB's
49 size_t _allocated; // in HeapWord units
50 size_t _wasted; // in HeapWord units
51 char tail[32];
52 static size_t FillerHeaderSize;
53 static size_t AlignmentReserve;
54
55 // Flush the stats supporting ergonomic sizing of PLAB's
56 // Should not be called directly
57 void flush_stats(PLABStats* stats);
58
59 public:
60 // Initializes the buffer to be empty, but with the given "word_sz".
61 // Must get initialized with "set_buf" for an allocation to succeed.
62 ParGCAllocBuffer(size_t word_sz);
63
64 static const size_t min_size() {
65 return ThreadLocalAllocBuffer::min_size();
66 }
67
68 static const size_t max_size() {
69 return ThreadLocalAllocBuffer::max_size();
70 }
71
72 // If an allocation of the given "word_sz" can be satisfied within the
73 // buffer, do the allocation, returning a pointer to the start of the
74 // allocated block. If the allocation request cannot be satisfied,
75 // return NULL.
76 HeapWord* allocate(size_t word_sz) {
77 HeapWord* res = _top;
78 if (pointer_delta(_end, _top) >= word_sz) {
79 _top = _top + word_sz;
80 return res;
81 } else {
82 return NULL;
83 }
84 }
85
86 // Undo the last allocation in the buffer, which is required to be of the
87 // "obj" of the given "word_sz".
88 void undo_allocation(HeapWord* obj, size_t word_sz) {
89 assert(pointer_delta(_top, _bottom) >= word_sz, "Bad undo");
90 assert(pointer_delta(_top, obj) == word_sz, "Bad undo");
91 _top = obj;
92 }
93
94 // The total (word) size of the buffer, including both allocated and
95 // unallocted space.
96 size_t word_sz() { return _word_sz; }
97
98 // Should only be done if we are about to reset with a new buffer of the
99 // given size.
100 void set_word_size(size_t new_word_sz) {
101 assert(new_word_sz > AlignmentReserve, "Too small");
102 _word_sz = new_word_sz;
103 }
104
105 // The number of words of unallocated space remaining in the buffer.
106 size_t words_remaining() {
107 assert(_end >= _top, "Negative buffer");
108 return pointer_delta(_end, _top, HeapWordSize);
109 }
110
111 bool contains(void* addr) {
112 return (void*)_bottom <= addr && addr < (void*)_hard_end;
113 }
114
115 // Sets the space of the buffer to be [buf, space+word_sz()).
116 void set_buf(HeapWord* buf) {
117 _bottom = buf;
118 _top = _bottom;
119 _hard_end = _bottom + word_sz();
120 _end = _hard_end - AlignmentReserve;
121 assert(_end >= _top, "Negative buffer");
122 // In support of ergonomic sizing
123 _allocated += word_sz();
124 }
125
126 // Flush the stats supporting ergonomic sizing of PLAB's
127 // and retire the current buffer.
128 void flush_stats_and_retire(PLABStats* stats, bool end_of_gc, bool retain) {
129 // We flush the stats first in order to get a reading of
130 // unused space in the last buffer.
131 if (ResizePLAB) {
132 flush_stats(stats);
133
134 // Since we have flushed the stats we need to clear
135 // the _allocated and _wasted fields. Not doing so
136 // will artifically inflate the values in the stats
137 // to which we add them.
138 // The next time we flush these values, we will add
139 // what we have just flushed in addition to the size
140 // of the buffers allocated between now and then.
141 _allocated = 0;
142 _wasted = 0;
143 }
144 // Retire the last allocation buffer.
145 retire(end_of_gc, retain);
146 }
147
148 // Force future allocations to fail and queries for contains()
149 // to return false
150 void invalidate() {
151 assert(!_retained, "Shouldn't retain an invalidated buffer.");
152 _end = _hard_end;
153 _wasted += pointer_delta(_end, _top); // unused space
154 _top = _end; // force future allocations to fail
155 _bottom = _end; // force future contains() queries to return false
156 }
157
158 // Fills in the unallocated portion of the buffer with a garbage object.
159 // If "end_of_gc" is TRUE, is after the last use in the GC. IF "retain"
160 // is true, attempt to re-use the unused portion in the next GC.
161 void retire(bool end_of_gc, bool retain);
162
163 void print() PRODUCT_RETURN;
164 };
165
166 // PLAB stats book-keeping
167 class PLABStats VALUE_OBJ_CLASS_SPEC {
168 size_t _allocated; // total allocated
169 size_t _wasted; // of which wasted (internal fragmentation)
170 size_t _unused; // Unused in last buffer
171 size_t _used; // derived = allocated - wasted - unused
172 size_t _desired_plab_sz;// output of filter (below), suitably trimmed and quantized
173 AdaptiveWeightedAverage
174 _filter; // integrator with decay
175
176 public:
177 PLABStats(size_t desired_plab_sz_, unsigned wt) :
178 _allocated(0),
179 _wasted(0),
180 _unused(0),
181 _used(0),
182 _desired_plab_sz(desired_plab_sz_),
183 _filter(wt)
184 {
185 size_t min_sz = min_size();
186 size_t max_sz = max_size();
187 size_t aligned_min_sz = align_object_size(min_sz);
188 size_t aligned_max_sz = align_object_size(max_sz);
189 assert(min_sz <= aligned_min_sz && max_sz >= aligned_max_sz &&
190 min_sz <= max_sz,
191 "PLAB clipping computation in adjust_desired_plab_sz()"
192 " may be incorrect");
193 }
194
195 static const size_t min_size() {
196 return ParGCAllocBuffer::min_size();
197 }
198
199 static const size_t max_size() {
200 return ParGCAllocBuffer::max_size();
201 }
202
203 size_t desired_plab_sz() {
204 return _desired_plab_sz;
205 }
206
207 void adjust_desired_plab_sz(uint no_of_gc_workers);
208 // filter computation, latches output to
209 // _desired_plab_sz, clears sensor accumulators
210
211 void add_allocated(size_t v) {
212 Atomic::add_ptr(v, &_allocated);
213 }
214
215 void add_unused(size_t v) {
216 Atomic::add_ptr(v, &_unused);
217 }
218
219 void add_wasted(size_t v) {
220 Atomic::add_ptr(v, &_wasted);
221 }
222 };
223
224 class ParGCAllocBufferWithBOT: public ParGCAllocBuffer {
225 BlockOffsetArrayContigSpace _bt;
226 BlockOffsetSharedArray* _bsa;
227 HeapWord* _true_end; // end of the whole ParGCAllocBuffer
228
229 static const size_t ChunkSizeInWords;
230 static const size_t ChunkSizeInBytes;
231 HeapWord* allocate_slow(size_t word_sz);
232
233 void fill_region_with_block(MemRegion mr, bool contig);
234
235 public:
236 ParGCAllocBufferWithBOT(size_t word_sz, BlockOffsetSharedArray* bsa);
237
238 HeapWord* allocate(size_t word_sz) {
239 HeapWord* res = ParGCAllocBuffer::allocate(word_sz);
240 if (res != NULL) {
241 _bt.alloc_block(res, word_sz);
242 } else {
243 res = allocate_slow(word_sz);
244 }
245 return res;
246 }
247
248 void undo_allocation(HeapWord* obj, size_t word_sz);
249
250 void set_buf(HeapWord* buf_start) {
251 ParGCAllocBuffer::set_buf(buf_start);
252 _true_end = _hard_end;
253 _bt.set_region(MemRegion(buf_start, word_sz()));
254 _bt.initialize_threshold();
255 }
256
257 void retire(bool end_of_gc, bool retain);
258
259 MemRegion range() {
260 return MemRegion(_top, _true_end);
261 }
262 };
263
264 #endif // SHARE_VM_GC_IMPLEMENTATION_PARNEW_PARGCALLOCBUFFER_HPP