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