| /* |
| * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #ifndef SHARE_VM_GC_CMS_ALLOCATIONSTATS_HPP |
| #define SHARE_VM_GC_CMS_ALLOCATIONSTATS_HPP |
| |
| #include "gc/shared/gcUtil.hpp" |
| #include "logging/log.hpp" |
| #include "memory/allocation.hpp" |
| #include "utilities/globalDefinitions.hpp" |
| #include "utilities/macros.hpp" |
| |
| class AllocationStats VALUE_OBJ_CLASS_SPEC { |
| // A duration threshold (in ms) used to filter |
| // possibly unreliable samples. |
| static float _threshold; |
| |
| // We measure the demand between the end of the previous sweep and |
| // beginning of this sweep: |
| // Count(end_last_sweep) - Count(start_this_sweep) |
| // + split_births(between) - split_deaths(between) |
| // The above number divided by the time since the end of the |
| // previous sweep gives us a time rate of demand for blocks |
| // of this size. We compute a padded average of this rate as |
| // our current estimate for the time rate of demand for blocks |
| // of this size. Similarly, we keep a padded average for the time |
| // between sweeps. Our current estimate for demand for blocks of |
| // this size is then simply computed as the product of these two |
| // estimates. |
| AdaptivePaddedAverage _demand_rate_estimate; |
| |
| ssize_t _desired; // Demand estimate computed as described above |
| ssize_t _coal_desired; // desired +/- small-percent for tuning coalescing |
| |
| ssize_t _surplus; // count - (desired +/- small-percent), |
| // used to tune splitting in best fit |
| ssize_t _bfr_surp; // surplus at start of current sweep |
| ssize_t _prev_sweep; // count from end of previous sweep |
| ssize_t _before_sweep; // count from before current sweep |
| ssize_t _coal_births; // additional chunks from coalescing |
| ssize_t _coal_deaths; // loss from coalescing |
| ssize_t _split_births; // additional chunks from splitting |
| ssize_t _split_deaths; // loss from splitting |
| size_t _returned_bytes; // number of bytes returned to list. |
| public: |
| void initialize(bool split_birth = false) { |
| AdaptivePaddedAverage* dummy = |
| new (&_demand_rate_estimate) AdaptivePaddedAverage(CMS_FLSWeight, |
| CMS_FLSPadding); |
| _desired = 0; |
| _coal_desired = 0; |
| _surplus = 0; |
| _bfr_surp = 0; |
| _prev_sweep = 0; |
| _before_sweep = 0; |
| _coal_births = 0; |
| _coal_deaths = 0; |
| _split_births = (split_birth ? 1 : 0); |
| _split_deaths = 0; |
| _returned_bytes = 0; |
| } |
| |
| AllocationStats() { |
| initialize(); |
| } |
| |
| // The rate estimate is in blocks per second. |
| void compute_desired(size_t count, |
| float inter_sweep_current, |
| float inter_sweep_estimate, |
| float intra_sweep_estimate) { |
| // If the latest inter-sweep time is below our granularity |
| // of measurement, we may call in here with |
| // inter_sweep_current == 0. However, even for suitably small |
| // but non-zero inter-sweep durations, we may not trust the accuracy |
| // of accumulated data, since it has not been "integrated" |
| // (read "low-pass-filtered") long enough, and would be |
| // vulnerable to noisy glitches. In such cases, we |
| // ignore the current sample and use currently available |
| // historical estimates. |
| assert(prev_sweep() + split_births() + coal_births() // "Total Production Stock" |
| >= split_deaths() + coal_deaths() + (ssize_t)count, // "Current stock + depletion" |
| "Conservation Principle"); |
| if (inter_sweep_current > _threshold) { |
| ssize_t demand = prev_sweep() - (ssize_t)count + split_births() + coal_births() |
| - split_deaths() - coal_deaths(); |
| assert(demand >= 0, |
| "Demand (" SSIZE_FORMAT ") should be non-negative for " |
| PTR_FORMAT " (size=" SIZE_FORMAT ")", |
| demand, p2i(this), count); |
| // Defensive: adjust for imprecision in event counting |
| if (demand < 0) { |
| demand = 0; |
| } |
| float old_rate = _demand_rate_estimate.padded_average(); |
| float rate = ((float)demand)/inter_sweep_current; |
| _demand_rate_estimate.sample(rate); |
| float new_rate = _demand_rate_estimate.padded_average(); |
| ssize_t old_desired = _desired; |
| float delta_ise = (CMSExtrapolateSweep ? intra_sweep_estimate : 0.0); |
| _desired = (ssize_t)(new_rate * (inter_sweep_estimate + delta_ise)); |
| log_trace(gc, freelist)("demand: " SSIZE_FORMAT ", old_rate: %f, current_rate: %f, " |
| "new_rate: %f, old_desired: " SSIZE_FORMAT ", new_desired: " SSIZE_FORMAT, |
| demand, old_rate, rate, new_rate, old_desired, _desired); |
| } |
| } |
| |
| ssize_t desired() const { return _desired; } |
| void set_desired(ssize_t v) { _desired = v; } |
| |
| ssize_t coal_desired() const { return _coal_desired; } |
| void set_coal_desired(ssize_t v) { _coal_desired = v; } |
| |
| ssize_t surplus() const { return _surplus; } |
| void set_surplus(ssize_t v) { _surplus = v; } |
| void increment_surplus() { _surplus++; } |
| void decrement_surplus() { _surplus--; } |
| |
| ssize_t bfr_surp() const { return _bfr_surp; } |
| void set_bfr_surp(ssize_t v) { _bfr_surp = v; } |
| ssize_t prev_sweep() const { return _prev_sweep; } |
| void set_prev_sweep(ssize_t v) { _prev_sweep = v; } |
| ssize_t before_sweep() const { return _before_sweep; } |
| void set_before_sweep(ssize_t v) { _before_sweep = v; } |
| |
| ssize_t coal_births() const { return _coal_births; } |
| void set_coal_births(ssize_t v) { _coal_births = v; } |
| void increment_coal_births() { _coal_births++; } |
| |
| ssize_t coal_deaths() const { return _coal_deaths; } |
| void set_coal_deaths(ssize_t v) { _coal_deaths = v; } |
| void increment_coal_deaths() { _coal_deaths++; } |
| |
| ssize_t split_births() const { return _split_births; } |
| void set_split_births(ssize_t v) { _split_births = v; } |
| void increment_split_births() { _split_births++; } |
| |
| ssize_t split_deaths() const { return _split_deaths; } |
| void set_split_deaths(ssize_t v) { _split_deaths = v; } |
| void increment_split_deaths() { _split_deaths++; } |
| |
| NOT_PRODUCT( |
| size_t returned_bytes() const { return _returned_bytes; } |
| void set_returned_bytes(size_t v) { _returned_bytes = v; } |
| ) |
| }; |
| |
| #endif // SHARE_VM_GC_CMS_ALLOCATIONSTATS_HPP |