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_CMS_ALLOCATIONSTATS_HPP 26 #define SHARE_VM_GC_CMS_ALLOCATIONSTATS_HPP 27 28 #include "gc/shared/gcUtil.hpp" 29 #include "logging/log.hpp" 30 #include "memory/allocation.hpp" 31 #include "utilities/globalDefinitions.hpp" 32 #include "utilities/macros.hpp" 33 34 class AllocationStats VALUE_OBJ_CLASS_SPEC { 35 // A duration threshold (in ms) used to filter 36 // possibly unreliable samples. 37 static float _threshold; 38 39 // We measure the demand between the end of the previous sweep and 40 // beginning of this sweep: 41 // Count(end_last_sweep) - Count(start_this_sweep) 42 // + split_births(between) - split_deaths(between) 43 // The above number divided by the time since the end of the 44 // previous sweep gives us a time rate of demand for blocks 45 // of this size. We compute a padded average of this rate as 46 // our current estimate for the time rate of demand for blocks 47 // of this size. Similarly, we keep a padded average for the time 48 // between sweeps. Our current estimate for demand for blocks of 49 // this size is then simply computed as the product of these two 50 // estimates. 51 AdaptivePaddedAverage _demand_rate_estimate; 52 53 ssize_t _desired; // Demand estimate computed as described above 54 ssize_t _coal_desired; // desired +/- small-percent for tuning coalescing 55 56 ssize_t _surplus; // count - (desired +/- small-percent), 57 // used to tune splitting in best fit 58 ssize_t _bfr_surp; // surplus at start of current sweep 59 ssize_t _prev_sweep; // count from end of previous sweep 60 ssize_t _before_sweep; // count from before current sweep 61 ssize_t _coal_births; // additional chunks from coalescing 62 ssize_t _coal_deaths; // loss from coalescing 63 ssize_t _split_births; // additional chunks from splitting 64 ssize_t _split_deaths; // loss from splitting 65 size_t _returned_bytes; // number of bytes returned to list. 66 public: 67 void initialize(bool split_birth = false) { 68 AdaptivePaddedAverage* dummy = 69 new (&_demand_rate_estimate) AdaptivePaddedAverage(CMS_FLSWeight, 70 CMS_FLSPadding); 71 _desired = 0; 72 _coal_desired = 0; 73 _surplus = 0; 74 _bfr_surp = 0; 75 _prev_sweep = 0; 76 _before_sweep = 0; 77 _coal_births = 0; 78 _coal_deaths = 0; 79 _split_births = (split_birth ? 1 : 0); 80 _split_deaths = 0; 81 _returned_bytes = 0; 82 } 83 84 AllocationStats() { 85 initialize(); 86 } 87 88 // The rate estimate is in blocks per second. 89 void compute_desired(size_t count, 90 float inter_sweep_current, 91 float inter_sweep_estimate, 92 float intra_sweep_estimate) { 93 // If the latest inter-sweep time is below our granularity 94 // of measurement, we may call in here with 95 // inter_sweep_current == 0. However, even for suitably small 96 // but non-zero inter-sweep durations, we may not trust the accuracy 97 // of accumulated data, since it has not been "integrated" 98 // (read "low-pass-filtered") long enough, and would be 99 // vulnerable to noisy glitches. In such cases, we 100 // ignore the current sample and use currently available 101 // historical estimates. 102 assert(prev_sweep() + split_births() + coal_births() // "Total Production Stock" 103 >= split_deaths() + coal_deaths() + (ssize_t)count, // "Current stock + depletion" 104 "Conservation Principle"); 105 if (inter_sweep_current > _threshold) { 106 ssize_t demand = prev_sweep() - (ssize_t)count + split_births() + coal_births() 107 - split_deaths() - coal_deaths(); 108 assert(demand >= 0, 109 "Demand (" SSIZE_FORMAT ") should be non-negative for " 110 PTR_FORMAT " (size=" SIZE_FORMAT ")", 111 demand, p2i(this), count); 112 // Defensive: adjust for imprecision in event counting 113 if (demand < 0) { 114 demand = 0; 115 } 116 float old_rate = _demand_rate_estimate.padded_average(); 117 float rate = ((float)demand)/inter_sweep_current; 118 _demand_rate_estimate.sample(rate); 119 float new_rate = _demand_rate_estimate.padded_average(); 120 ssize_t old_desired = _desired; 121 float delta_ise = (CMSExtrapolateSweep ? intra_sweep_estimate : 0.0); 122 _desired = (ssize_t)(new_rate * (inter_sweep_estimate + delta_ise)); 123 log_trace(gc, freelist)("demand: " SSIZE_FORMAT ", old_rate: %f, current_rate: %f, " 124 "new_rate: %f, old_desired: " SSIZE_FORMAT ", new_desired: " SSIZE_FORMAT, 125 demand, old_rate, rate, new_rate, old_desired, _desired); 126 } 127 } 128 129 ssize_t desired() const { return _desired; } 130 void set_desired(ssize_t v) { _desired = v; } 131 132 ssize_t coal_desired() const { return _coal_desired; } 133 void set_coal_desired(ssize_t v) { _coal_desired = v; } 134 135 ssize_t surplus() const { return _surplus; } 136 void set_surplus(ssize_t v) { _surplus = v; } 137 void increment_surplus() { _surplus++; } 138 void decrement_surplus() { _surplus--; } 139 140 ssize_t bfr_surp() const { return _bfr_surp; } 141 void set_bfr_surp(ssize_t v) { _bfr_surp = v; } 142 ssize_t prev_sweep() const { return _prev_sweep; } 143 void set_prev_sweep(ssize_t v) { _prev_sweep = v; } 144 ssize_t before_sweep() const { return _before_sweep; } 145 void set_before_sweep(ssize_t v) { _before_sweep = v; } 146 147 ssize_t coal_births() const { return _coal_births; } 148 void set_coal_births(ssize_t v) { _coal_births = v; } 149 void increment_coal_births() { _coal_births++; } 150 151 ssize_t coal_deaths() const { return _coal_deaths; } 152 void set_coal_deaths(ssize_t v) { _coal_deaths = v; } 153 void increment_coal_deaths() { _coal_deaths++; } 154 155 ssize_t split_births() const { return _split_births; } 156 void set_split_births(ssize_t v) { _split_births = v; } 157 void increment_split_births() { _split_births++; } 158 159 ssize_t split_deaths() const { return _split_deaths; } 160 void set_split_deaths(ssize_t v) { _split_deaths = v; } 161 void increment_split_deaths() { _split_deaths++; } 162 163 NOT_PRODUCT( 164 size_t returned_bytes() const { return _returned_bytes; } 165 void set_returned_bytes(size_t v) { _returned_bytes = v; } 166 ) 167 }; 168 169 #endif // SHARE_VM_GC_CMS_ALLOCATIONSTATS_HPP