1 /* |
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2 * Copyright 2001-2005 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
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20 * CA 95054 USA or visit www.sun.com if you need additional information or |
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21 * have any questions. |
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22 * |
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23 */ |
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24 |
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25 class AllocationStats VALUE_OBJ_CLASS_SPEC { |
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26 // A duration threshold (in ms) used to filter |
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27 // possibly unreliable samples. |
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28 static float _threshold; |
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29 |
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30 // We measure the demand between the end of the previous sweep and |
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31 // beginning of this sweep: |
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32 // Count(end_last_sweep) - Count(start_this_sweep) |
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33 // + splitBirths(between) - splitDeaths(between) |
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34 // The above number divided by the time since the start [END???] of the |
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35 // previous sweep gives us a time rate of demand for blocks |
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36 // of this size. We compute a padded average of this rate as |
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37 // our current estimate for the time rate of demand for blocks |
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38 // of this size. Similarly, we keep a padded average for the time |
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39 // between sweeps. Our current estimate for demand for blocks of |
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40 // this size is then simply computed as the product of these two |
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41 // estimates. |
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42 AdaptivePaddedAverage _demand_rate_estimate; |
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43 |
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44 ssize_t _desired; // Estimate computed as described above |
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45 ssize_t _coalDesired; // desired +/- small-percent for tuning coalescing |
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46 |
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47 ssize_t _surplus; // count - (desired +/- small-percent), |
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48 // used to tune splitting in best fit |
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49 ssize_t _bfrSurp; // surplus at start of current sweep |
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50 ssize_t _prevSweep; // count from end of previous sweep |
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51 ssize_t _beforeSweep; // count from before current sweep |
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52 ssize_t _coalBirths; // additional chunks from coalescing |
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53 ssize_t _coalDeaths; // loss from coalescing |
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54 ssize_t _splitBirths; // additional chunks from splitting |
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55 ssize_t _splitDeaths; // loss from splitting |
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56 size_t _returnedBytes; // number of bytes returned to list. |
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57 public: |
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58 void initialize() { |
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59 AdaptivePaddedAverage* dummy = |
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60 new (&_demand_rate_estimate) AdaptivePaddedAverage(CMS_FLSWeight, |
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61 CMS_FLSPadding); |
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62 _desired = 0; |
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63 _coalDesired = 0; |
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64 _surplus = 0; |
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65 _bfrSurp = 0; |
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66 _prevSweep = 0; |
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67 _beforeSweep = 0; |
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68 _coalBirths = 0; |
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69 _coalDeaths = 0; |
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70 _splitBirths = 0; |
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71 _splitDeaths = 0; |
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72 _returnedBytes = 0; |
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73 } |
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74 |
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75 AllocationStats() { |
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76 initialize(); |
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77 } |
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78 // The rate estimate is in blocks per second. |
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79 void compute_desired(size_t count, |
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80 float inter_sweep_current, |
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81 float inter_sweep_estimate) { |
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82 // If the latest inter-sweep time is below our granularity |
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83 // of measurement, we may call in here with |
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84 // inter_sweep_current == 0. However, even for suitably small |
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85 // but non-zero inter-sweep durations, we may not trust the accuracy |
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86 // of accumulated data, since it has not been "integrated" |
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87 // (read "low-pass-filtered") long enough, and would be |
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88 // vulnerable to noisy glitches. In such cases, we |
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89 // ignore the current sample and use currently available |
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90 // historical estimates. |
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91 if (inter_sweep_current > _threshold) { |
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92 ssize_t demand = prevSweep() - count + splitBirths() - splitDeaths(); |
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93 float rate = ((float)demand)/inter_sweep_current; |
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94 _demand_rate_estimate.sample(rate); |
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95 _desired = (ssize_t)(_demand_rate_estimate.padded_average() |
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96 *inter_sweep_estimate); |
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97 } |
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98 } |
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99 |
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100 ssize_t desired() const { return _desired; } |
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101 ssize_t coalDesired() const { return _coalDesired; } |
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102 void set_coalDesired(ssize_t v) { _coalDesired = v; } |
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103 |
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104 ssize_t surplus() const { return _surplus; } |
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105 void set_surplus(ssize_t v) { _surplus = v; } |
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106 void increment_surplus() { _surplus++; } |
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107 void decrement_surplus() { _surplus--; } |
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108 |
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109 ssize_t bfrSurp() const { return _bfrSurp; } |
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110 void set_bfrSurp(ssize_t v) { _bfrSurp = v; } |
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111 ssize_t prevSweep() const { return _prevSweep; } |
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112 void set_prevSweep(ssize_t v) { _prevSweep = v; } |
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113 ssize_t beforeSweep() const { return _beforeSweep; } |
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114 void set_beforeSweep(ssize_t v) { _beforeSweep = v; } |
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115 |
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116 ssize_t coalBirths() const { return _coalBirths; } |
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117 void set_coalBirths(ssize_t v) { _coalBirths = v; } |
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118 void increment_coalBirths() { _coalBirths++; } |
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119 |
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120 ssize_t coalDeaths() const { return _coalDeaths; } |
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121 void set_coalDeaths(ssize_t v) { _coalDeaths = v; } |
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122 void increment_coalDeaths() { _coalDeaths++; } |
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123 |
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124 ssize_t splitBirths() const { return _splitBirths; } |
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125 void set_splitBirths(ssize_t v) { _splitBirths = v; } |
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126 void increment_splitBirths() { _splitBirths++; } |
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127 |
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128 ssize_t splitDeaths() const { return _splitDeaths; } |
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129 void set_splitDeaths(ssize_t v) { _splitDeaths = v; } |
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130 void increment_splitDeaths() { _splitDeaths++; } |
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131 |
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132 NOT_PRODUCT( |
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133 size_t returnedBytes() const { return _returnedBytes; } |
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134 void set_returnedBytes(size_t v) { _returnedBytes = v; } |
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135 ) |
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136 }; |
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