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