137 lines
3.9 KiB
C++
137 lines
3.9 KiB
C++
/*
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* Copyright (C) 2015-2019 Robin Gareus <robin@gareus.org>
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* Copyright (C) 2015 Tim Mayberry <mojofunk@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef ARDOUR_DSP_LOAD_CALCULATOR_H
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#define ARDOUR_DSP_LOAD_CALCULATOR_H
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#include <glib.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <cassert>
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#include <algorithm>
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namespace ARDOUR {
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class DSPLoadCalculator {
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public:
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DSPLoadCalculator()
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: m_max_time_us(0)
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, m_start_timestamp_us(0)
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, m_stop_timestamp_us(0)
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, m_alpha(0)
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, m_dsp_load(0)
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{
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m_calc_avg_load = NULL != g_getenv("ARDOUR_AVG_DSP_LOAD");
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}
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void reset () {
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m_dsp_load = 0;
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m_start_timestamp_us = 0;
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m_stop_timestamp_us = 0;
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}
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void set_max_time(double samplerate, uint32_t period_size) {
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m_max_time_us = period_size * 1e6 / samplerate;
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m_alpha = 0.2f * (m_max_time_us * 1e-6f);
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}
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void set_max_time_us(uint64_t max_time_us) {
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assert(max_time_us != 0);
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m_max_time_us = max_time_us;
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m_alpha = 0.2f * (m_max_time_us * 1e-6f);
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}
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int64_t get_max_time_us() const { return m_max_time_us; }
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void set_start_timestamp_us(int64_t start_timestamp_us) {
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m_start_timestamp_us = start_timestamp_us;
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}
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void set_stop_timestamp_us(int64_t stop_timestamp_us)
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{
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m_stop_timestamp_us = stop_timestamp_us;
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/* querying the performance counter can fail occasionally (-1).
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* Also on some multi-core systems, timers are CPU specific and not
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* synchronized. We assume they differ more than a few milliseconds
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* (4 * nominal cycle time) and simply ignore cases where the
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* execution switches cores.
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*/
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if (m_start_timestamp_us < 0 || m_stop_timestamp_us < 0 ||
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m_start_timestamp_us > m_stop_timestamp_us ||
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elapsed_time_us() > max_timer_error_us()) {
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return;
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}
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assert (m_max_time_us > 0);
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const float load = (float) elapsed_time_us() / (float)m_max_time_us;
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if ((m_calc_avg_load && load > .95f) || (!m_calc_avg_load && (load > m_dsp_load || load > 1.f))) {
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m_dsp_load = load;
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} else {
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m_dsp_load = std::min (1.f, m_dsp_load);
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m_dsp_load += m_alpha * (load - m_dsp_load) + 1e-12;
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}
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}
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int64_t elapsed_time_us()
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{
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return m_stop_timestamp_us - m_start_timestamp_us;
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}
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/**
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* @return a decimal value between 0.0 and 1.0 representing the percentage
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* of time spent between start and stop in proportion to the max expected time
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* in microseconds(us).
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*/
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float get_dsp_load() const
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{
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assert (m_dsp_load >= 0.f); // since stop > start is assured this cannot happen.
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return std::min (1.f, m_dsp_load);
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}
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/**
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* @return an unbound value representing the percentage of time spent between
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* start and stop in proportion to the max expected time in microseconds(us).
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* This is useful for cases to estimate overload (e.g. Dummy backend)
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*/
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float get_dsp_load_unbound() const
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{
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assert (m_dsp_load >= 0.f);
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return m_dsp_load;
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}
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/**
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* The maximum error in timestamp values that will be tolerated before the
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* current dsp load sample will be ignored
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*/
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int64_t max_timer_error_us() { return 4 * m_max_time_us; }
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private: // data
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bool m_calc_avg_load;
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int64_t m_max_time_us;
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int64_t m_start_timestamp_us;
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int64_t m_stop_timestamp_us;
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float m_alpha;
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float m_dsp_load;
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};
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} // namespace ARDOUR
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#endif // ARDOUR_DSP_LOAD_CALCULATOR_H
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