rev 7799 : imported patch 8073466-remove-ratining-functionality-in-pargcallocbuffer
1 /* 2 * Copyright (c) 2001, 2015, 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 "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 ParGCAllocBuffer: 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 public: 52 // Initializes the buffer to be empty, but with the given "word_sz". 53 // Must get initialized with "set_buf" for an allocation to succeed. 54 ParGCAllocBuffer(size_t word_sz); 55 virtual ~ParGCAllocBuffer() {} 56 57 // Minimum PLAB size. 58 static const size_t min_size(); 59 // Maximum PLAB size. 60 static const size_t max_size(); 61 62 // If an allocation of the given "word_sz" can be satisfied within the 63 // buffer, do the allocation, returning a pointer to the start of the 64 // allocated block. If the allocation request cannot be satisfied, 65 // return NULL. 66 HeapWord* allocate(size_t word_sz) { 67 HeapWord* res = _top; 68 if (pointer_delta(_end, _top) >= word_sz) { 69 _top = _top + word_sz; 70 return res; 71 } else { 72 return NULL; 73 } 74 } 75 76 // Allocate the object aligned to "alignment_in_bytes". 77 HeapWord* allocate_aligned(size_t word_sz, unsigned short alignment_in_bytes); 78 79 // Undo the last allocation in the buffer, which is required to be of the 80 // "obj" of the given "word_sz". 81 void undo_allocation(HeapWord* obj, size_t word_sz) { 82 assert(pointer_delta(_top, _bottom) >= word_sz, "Bad undo"); 83 assert(pointer_delta(_top, obj) == word_sz, "Bad undo"); 84 _top = obj; 85 } 86 87 // The total (word) size of the buffer, including both allocated and 88 // unallocated space. 89 size_t word_sz() { return _word_sz; } 90 91 // Should only be done if we are about to reset with a new buffer of the 92 // given size. 93 void set_word_size(size_t new_word_sz) { 94 assert(new_word_sz > AlignmentReserve, "Too small"); 95 _word_sz = new_word_sz; 96 } 97 98 // The number of words of unallocated space remaining in the buffer. 99 size_t words_remaining() { 100 assert(_end >= _top, "Negative buffer"); 101 return pointer_delta(_end, _top, HeapWordSize); 102 } 103 104 bool contains(void* addr) { 105 return (void*)_bottom <= addr && addr < (void*)_hard_end; 106 } 107 108 // Sets the space of the buffer to be [buf, space+word_sz()). 109 virtual void set_buf(HeapWord* buf) { 110 _bottom = buf; 111 _top = _bottom; 112 _hard_end = _bottom + word_sz(); 113 _end = _hard_end - AlignmentReserve; 114 assert(_end >= _top, "Negative buffer"); 115 // In support of ergonomic sizing 116 _allocated += word_sz(); 117 } 118 119 // Flush allocation statistics into the given PLABStats supporting ergonomic 120 // sizing of PLAB's and retire the current buffer. 121 void flush_and_retire_stats(PLABStats* stats); 122 123 // Force future allocations to fail and queries for contains() 124 // to return false 125 void invalidate() { 126 _end = _hard_end; 127 _wasted += pointer_delta(_end, _top); // unused space 128 _top = _end; // force future allocations to fail 129 _bottom = _end; // force future contains() queries to return false 130 } 131 132 // Fills in the unallocated portion of the buffer with a garbage object and update 133 // statistics. 134 virtual void retire(); 135 136 void print() PRODUCT_RETURN; 137 }; 138 139 // PLAB book-keeping. 140 class PLABStats VALUE_OBJ_CLASS_SPEC { 141 size_t _allocated; // Total allocated 142 size_t _wasted; // of which wasted (internal fragmentation) 143 size_t _unused; // Unused in last buffer 144 size_t _desired_plab_sz;// Output of filter (below), suitably trimmed and quantized 145 AdaptiveWeightedAverage 146 _filter; // Integrator with decay 147 148 void reset() { 149 _allocated = 0; 150 _wasted = 0; 151 _unused = 0; 152 } 153 public: 154 PLABStats(size_t desired_plab_sz_, unsigned wt) : 155 _allocated(0), 156 _wasted(0), 157 _unused(0), 158 _desired_plab_sz(desired_plab_sz_), 159 _filter(wt) 160 { } 161 162 static const size_t min_size() { 163 return ParGCAllocBuffer::min_size(); 164 } 165 166 static const size_t max_size() { 167 return ParGCAllocBuffer::max_size(); 168 } 169 170 size_t desired_plab_sz() { 171 return _desired_plab_sz; 172 } 173 174 // Updates the current desired PLAB size. Computes the new desired PLAB size, 175 // updates _desired_plab_sz and clears sensor accumulators. 176 void adjust_desired_plab_sz(uint no_of_gc_workers); 177 178 void add_allocated(size_t v) { 179 Atomic::add_ptr(v, &_allocated); 180 } 181 182 void add_unused(size_t v) { 183 Atomic::add_ptr(v, &_unused); 184 } 185 186 void add_wasted(size_t v) { 187 Atomic::add_ptr(v, &_wasted); 188 } 189 }; 190 191 #endif // SHARE_VM_GC_IMPLEMENTATION_PARNEW_PARGCALLOCBUFFER_HPP --- EOF ---