2 * Copyright (C) 2015 Tim Mayberry <mojofunk@gmail.com>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19 #ifndef ARDOUR_DSP_LOAD_CALCULATOR_H
20 #define ARDOUR_DSP_LOAD_CALCULATOR_H
28 class DSPLoadCalculator {
32 , m_start_timestamp_us(0)
33 , m_stop_timestamp_us(0)
39 void set_max_time(double samplerate, uint32_t period_size) {
40 m_max_time_us = period_size * 1e6 / samplerate;
43 void set_max_time_us(uint64_t max_time_us) {
44 assert(max_time_us != 0);
45 m_max_time_us = max_time_us;
48 int64_t get_max_time_us() const { return m_max_time_us; }
50 void set_start_timestamp_us(int64_t start_timestamp_us)
52 m_start_timestamp_us = start_timestamp_us;
55 void set_stop_timestamp_us(int64_t stop_timestamp_us)
57 m_stop_timestamp_us = stop_timestamp_us;
59 /* querying the performance counter can fail occasionally (-1).
60 * Also on some multi-core systems, timers are CPU specific and not
61 * synchronized. We assume they differ more than a few milliseconds
62 * (4 * nominal cycle time) and simply ignore cases where the
63 * execution switches cores.
65 if (m_start_timestamp_us < 0 || m_stop_timestamp_us < 0 ||
66 m_start_timestamp_us > m_stop_timestamp_us ||
67 elapsed_time_us() > max_timer_error_us()) {
71 const float load = (float) elapsed_time_us() / (float)m_max_time_us;
72 if (load > m_dsp_load || load > 1.0) {
75 const float alpha = 0.2f * (m_max_time_us * 1e-6f);
76 m_dsp_load = std::min (1.f, m_dsp_load);
77 m_dsp_load += alpha * (load - m_dsp_load) + 1e-12;
81 int64_t elapsed_time_us()
83 return m_stop_timestamp_us - m_start_timestamp_us;
87 * @return a decimal value between 0.0 and 1.0 representing the percentage
88 * of time spent between start and stop in proportion to the max expected time
89 * in microseconds(us).
91 float get_dsp_load() const
93 assert (m_dsp_load >= 0.f); // since stop > start is assured this cannot happen.
94 return std::min (1.f, m_dsp_load);
98 * @return an unbound value representing the percentage of time spent between
99 * start and stop in proportion to the max expected time in microseconds(us).
100 * This is useful for cases to estimate overload (e.g. Dummy backend)
102 float get_dsp_load_unbound() const
104 assert (m_dsp_load >= 0.f);
109 * The maximum error in timestamp values that will be tolerated before the
110 * current dsp load sample will be ignored
112 int64_t max_timer_error_us() { return 4 * m_max_time_us; }
115 int64_t m_max_time_us;
116 int64_t m_start_timestamp_us;
117 int64_t m_stop_timestamp_us;
121 } // namespace ARDOUR
123 #endif // ARDOUR_DSP_LOAD_CALCULATOR_H