1// SPDX-License-Identifier: GPL-2.0-or-later
2/*  cpufreq-bench CPUFreq microbenchmark
3 *
4 *  Copyright (C) 2008 Christian Kornacker <ckornacker@suse.de>
5 */
6
7#include <stdio.h>
8#include <unistd.h>
9#include <math.h>
10
11#include "config.h"
12#include "system.h"
13#include "benchmark.h"
14
15/* Print out progress if we log into a file */
16#define show_progress(total_time, progress_time)	\
17if (config->output != stdout) {				\
18	fprintf(stdout, "Progress: %02lu %%\r",		\
19		(progress_time * 100) / total_time);	\
20	fflush(stdout);					\
21}
22
23/**
24 * compute how many rounds of calculation we should do
25 * to get the given load time
26 *
27 * @param load aimed load time in ��s
28 *
29 * @retval rounds of calculation
30 **/
31
32unsigned int calculate_timespace(long load, struct config *config)
33{
34	int i;
35	long long now, then;
36	unsigned int estimated = GAUGECOUNT;
37	unsigned int rounds = 0;
38	unsigned int timed = 0;
39
40	if (config->verbose)
41		printf("calibrating load of %lius, please wait...\n", load);
42
43	/* get the initial calculation time for a specific number of rounds */
44	now = get_time();
45	ROUNDS(estimated);
46	then = get_time();
47
48	timed = (unsigned int)(then - now);
49
50	/* approximation of the wanted load time by comparing with the
51	 * initial calculation time */
52	for (i = 0; i < 4; i++) {
53		rounds = (unsigned int)(load * estimated / timed);
54		dprintf("calibrating with %u rounds\n", rounds);
55		now = get_time();
56		ROUNDS(rounds);
57		then = get_time();
58
59		timed = (unsigned int)(then - now);
60		estimated = rounds;
61	}
62	if (config->verbose)
63		printf("calibration done\n");
64
65	return estimated;
66}
67
68/**
69 * benchmark
70 * generates a specific sleep an load time with the performance
71 * governor and compares the used time for same calculations done
72 * with the configured powersave governor
73 *
74 * @param config config values for the benchmark
75 *
76 **/
77
78void start_benchmark(struct config *config)
79{
80	unsigned int _round, cycle;
81	long long now, then;
82	long sleep_time = 0, load_time = 0;
83	long performance_time = 0, powersave_time = 0;
84	unsigned int calculations;
85	unsigned long total_time = 0, progress_time = 0;
86
87	sleep_time = config->sleep;
88	load_time = config->load;
89
90	/* For the progress bar */
91	for (_round = 1; _round <= config->rounds; _round++)
92		total_time += _round * (config->sleep + config->load);
93	total_time *= 2; /* powersave and performance cycles */
94
95	for (_round = 0; _round < config->rounds; _round++) {
96		performance_time = 0LL;
97		powersave_time = 0LL;
98
99		show_progress(total_time, progress_time);
100
101		/* set the cpufreq governor to "performance" which disables
102		 * P-State switching. */
103		if (set_cpufreq_governor("performance", config->cpu) != 0)
104			return;
105
106		/* calibrate the calculation time. the resulting calculation
107		 * _rounds should produce a load which matches the configured
108		 * load time */
109		calculations = calculate_timespace(load_time, config);
110
111		if (config->verbose)
112			printf("_round %i: doing %u cycles with %u calculations"
113			       " for %lius\n", _round + 1, config->cycles,
114			       calculations, load_time);
115
116		fprintf(config->output, "%u %li %li ",
117			_round, load_time, sleep_time);
118
119		if (config->verbose)
120			printf("average: %lius, rps:%li\n",
121				load_time / calculations,
122				1000000 * calculations / load_time);
123
124		/* do some sleep/load cycles with the performance governor */
125		for (cycle = 0; cycle < config->cycles; cycle++) {
126			now = get_time();
127			usleep(sleep_time);
128			ROUNDS(calculations);
129			then = get_time();
130			performance_time += then - now - sleep_time;
131			if (config->verbose)
132				printf("performance cycle took %lius, "
133					"sleep: %lius, "
134					"load: %lius, rounds: %u\n",
135					(long)(then - now), sleep_time,
136					load_time, calculations);
137		}
138		fprintf(config->output, "%li ",
139			performance_time / config->cycles);
140
141		progress_time += sleep_time + load_time;
142		show_progress(total_time, progress_time);
143
144		/* set the powersave governor which activates P-State switching
145		 * again */
146		if (set_cpufreq_governor(config->governor, config->cpu) != 0)
147			return;
148
149		/* again, do some sleep/load cycles with the
150		 * powersave governor */
151		for (cycle = 0; cycle < config->cycles; cycle++) {
152			now = get_time();
153			usleep(sleep_time);
154			ROUNDS(calculations);
155			then = get_time();
156			powersave_time += then - now - sleep_time;
157			if (config->verbose)
158				printf("powersave cycle took %lius, "
159					"sleep: %lius, "
160					"load: %lius, rounds: %u\n",
161					(long)(then - now), sleep_time,
162					load_time, calculations);
163		}
164
165		progress_time += sleep_time + load_time;
166
167		/* compare the average sleep/load cycles  */
168		fprintf(config->output, "%li ",
169			powersave_time / config->cycles);
170		fprintf(config->output, "%.3f\n",
171			performance_time * 100.0 / powersave_time);
172		fflush(config->output);
173
174		if (config->verbose)
175			printf("performance is at %.2f%%\n",
176				performance_time * 100.0 / powersave_time);
177
178		sleep_time += config->sleep_step;
179		load_time += config->load_step;
180	}
181}
182