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)	\
17 if (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 µs
28  *
29  * @retval rounds of calculation
30  **/
31 
32 unsigned 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 
78 void 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