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_us(uint64_t max_time_us) {
40 assert(max_time_us != 0);
41 m_max_time_us = max_time_us;
44 int64_t get_max_time_us() const { return m_max_time_us; }
46 void set_start_timestamp_us(int64_t start_timestamp_us)
48 m_start_timestamp_us = start_timestamp_us;
51 void set_stop_timestamp_us(int64_t stop_timestamp_us)
53 m_stop_timestamp_us = stop_timestamp_us;
55 /* querying the performance counter can fail occasionally (-1).
56 * Also on some multi-core systems, timers are CPU specific and not
57 * synchronized. We assume they differ more than a few milliseconds
58 * (4 * nominal cycle time) and simply ignore cases where the
59 * execution switches cores.
61 if (m_start_timestamp_us < 0 || m_stop_timestamp_us < 0 ||
62 m_start_timestamp_us > m_stop_timestamp_us ||
63 elapsed_time_us() > max_timer_error()) {
67 if (elapsed_time_us() > m_max_time_us) {
70 const float load = elapsed_time_us() / (float)m_max_time_us;
71 if (load > m_dsp_load) {
74 const float alpha = 0.2f * (m_max_time_us * 1e-6f);
75 m_dsp_load = m_dsp_load + alpha * (load - m_dsp_load) + 1e-12;
80 int64_t elapsed_time_us()
82 return m_stop_timestamp_us - m_start_timestamp_us;
86 * @return a decimal value between 0.0 and 1.0 representing the percentage
87 * of time spent between start and stop in proportion to the max expected time
88 * in microseconds(us).
90 float get_dsp_load() const
92 if (m_dsp_load > m_max_time_us) {
95 if (m_dsp_load < 0.0f) {
102 int64_t max_timer_error () { return 4 * m_max_time_us; }
105 int64_t m_max_time_us;
106 int64_t m_start_timestamp_us;
107 int64_t m_stop_timestamp_us;
111 } // namespace ARDOUR
113 #endif // ARDOUR_DSP_LOAD_CALCULATOR_H