1 /* |
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2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. |
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8 * |
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9 * This code is distributed in the hope that it will be useful, but WITHOUT |
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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12 * version 2 for more details (a copy is included in the LICENSE file that |
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13 * accompanied this code). |
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14 * |
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15 * You should have received a copy of the GNU General Public License version |
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16 * 2 along with this work; if not, write to the Free Software Foundation, |
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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18 * |
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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. |
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22 * |
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23 */ |
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24 |
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25 #include "precompiled.hpp" |
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26 #include "gc_implementation/shared/parGCAllocBuffer.hpp" |
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27 #include "memory/threadLocalAllocBuffer.hpp" |
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28 #include "oops/arrayOop.hpp" |
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29 #include "oops/oop.inline.hpp" |
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30 |
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31 size_t ParGCAllocBuffer::min_size() { |
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32 // Make sure that we return something that is larger than AlignmentReserve |
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33 return align_object_size(MAX2(MinTLABSize / HeapWordSize, (uintx)oopDesc::header_size())) + AlignmentReserve; |
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34 } |
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35 |
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36 size_t ParGCAllocBuffer::max_size() { |
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37 return ThreadLocalAllocBuffer::max_size(); |
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38 } |
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39 |
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40 ParGCAllocBuffer::ParGCAllocBuffer(size_t desired_plab_sz_) : |
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41 _word_sz(desired_plab_sz_), _bottom(NULL), _top(NULL), |
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42 _end(NULL), _hard_end(NULL), _allocated(0), _wasted(0) |
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43 { |
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44 // ArrayOopDesc::header_size depends on command line initialization. |
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45 AlignmentReserve = oopDesc::header_size() > MinObjAlignment ? align_object_size(arrayOopDesc::header_size(T_INT)) : 0; |
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46 assert(min_size() > AlignmentReserve, |
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47 err_msg("Minimum PLAB size " SIZE_FORMAT" must be larger than alignment reserve " SIZE_FORMAT" " |
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48 "to be able to contain objects", min_size(), AlignmentReserve)); |
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49 } |
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50 |
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51 // If the minimum object size is greater than MinObjAlignment, we can |
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52 // end up with a shard at the end of the buffer that's smaller than |
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53 // the smallest object. We can't allow that because the buffer must |
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54 // look like it's full of objects when we retire it, so we make |
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55 // sure we have enough space for a filler int array object. |
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56 size_t ParGCAllocBuffer::AlignmentReserve; |
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57 |
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58 void ParGCAllocBuffer::flush_and_retire_stats(PLABStats* stats) { |
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59 // Retire the last allocation buffer. |
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60 size_t unused = retire_internal(); |
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61 |
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62 // Now flush the statistics. |
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63 stats->add_allocated(_allocated); |
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64 stats->add_wasted(_wasted); |
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65 stats->add_unused(unused); |
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66 |
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67 // Since we have flushed the stats we need to clear the _allocated and _wasted |
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68 // fields in case somebody retains an instance of this over GCs. Not doing so |
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69 // will artifically inflate the values in the statistics. |
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70 _allocated = 0; |
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71 _wasted = 0; |
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72 } |
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73 |
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74 void ParGCAllocBuffer::retire() { |
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75 _wasted += retire_internal(); |
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76 } |
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77 |
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78 size_t ParGCAllocBuffer::retire_internal() { |
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79 size_t result = 0; |
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80 if (_top < _hard_end) { |
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81 CollectedHeap::fill_with_object(_top, _hard_end); |
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82 result += invalidate(); |
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83 } |
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84 return result; |
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85 } |
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86 |
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87 // Compute desired plab size and latch result for later |
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88 // use. This should be called once at the end of parallel |
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89 // scavenge; it clears the sensor accumulators. |
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90 void PLABStats::adjust_desired_plab_sz(uint no_of_gc_workers) { |
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91 assert(ResizePLAB, "Not set"); |
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92 |
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93 assert(is_object_aligned(max_size()) && min_size() <= max_size(), |
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94 "PLAB clipping computation may be incorrect"); |
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95 |
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96 if (_allocated == 0) { |
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97 assert(_unused == 0, |
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98 err_msg("Inconsistency in PLAB stats: " |
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99 "_allocated: "SIZE_FORMAT", " |
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100 "_wasted: "SIZE_FORMAT", " |
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101 "_unused: "SIZE_FORMAT, |
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102 _allocated, _wasted, _unused)); |
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103 |
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104 _allocated = 1; |
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105 } |
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106 double wasted_frac = (double)_unused / (double)_allocated; |
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107 size_t target_refills = (size_t)((wasted_frac * TargetSurvivorRatio) / TargetPLABWastePct); |
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108 if (target_refills == 0) { |
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109 target_refills = 1; |
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110 } |
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111 size_t used = _allocated - _wasted - _unused; |
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112 size_t recent_plab_sz = used / (target_refills * no_of_gc_workers); |
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113 // Take historical weighted average |
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114 _filter.sample(recent_plab_sz); |
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115 // Clip from above and below, and align to object boundary |
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116 size_t new_plab_sz = MAX2(min_size(), (size_t)_filter.average()); |
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117 new_plab_sz = MIN2(max_size(), new_plab_sz); |
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118 new_plab_sz = align_object_size(new_plab_sz); |
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119 // Latch the result |
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120 if (PrintPLAB) { |
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121 gclog_or_tty->print(" (plab_sz = " SIZE_FORMAT" desired_plab_sz = " SIZE_FORMAT") ", recent_plab_sz, new_plab_sz); |
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122 } |
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123 _desired_plab_sz = new_plab_sz; |
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124 |
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125 reset(); |
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126 } |
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127 |
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128 #ifndef PRODUCT |
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129 void ParGCAllocBuffer::print() { |
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130 gclog_or_tty->print_cr("parGCAllocBuffer: _bottom: " PTR_FORMAT " _top: " PTR_FORMAT |
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131 " _end: " PTR_FORMAT " _hard_end: " PTR_FORMAT ")", |
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132 p2i(_bottom), p2i(_top), p2i(_end), p2i(_hard_end)); |
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133 } |
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134 #endif // !PRODUCT |
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