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 = (1e6 / samplerate) * period_size;
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 if (elapsed_time_us() > m_max_time_us) {
74 const float load = elapsed_time_us() / (float)m_max_time_us;
75 if (load > m_dsp_load) {
78 const float alpha = 0.2f * (m_max_time_us * 1e-6f);
79 m_dsp_load = m_dsp_load + alpha * (load - m_dsp_load) + 1e-12;
84 int64_t elapsed_time_us()
86 return m_stop_timestamp_us - m_start_timestamp_us;
90 * @return a decimal value between 0.0 and 1.0 representing the percentage
91 * of time spent between start and stop in proportion to the max expected time
92 * in microseconds(us).
94 float get_dsp_load() const
96 if (m_dsp_load > m_max_time_us) {
99 if (m_dsp_load < 0.0f) {
106 * The maximum error in timestamp values that will be tolerated before the
107 * current dsp load sample will be ignored
109 int64_t max_timer_error_us() { return 4 * m_max_time_us; }
112 int64_t m_max_time_us;
113 int64_t m_start_timestamp_us;
114 int64_t m_stop_timestamp_us;
118 } // namespace ARDOUR
120 #endif // ARDOUR_DSP_LOAD_CALCULATOR_H