system.c

  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 <time.h>
  9#include <sys/time.h>
 10#include <sys/types.h>
 11#include <unistd.h>
 12
 13#include <sched.h>
 14
 15#include <cpufreq.h>
 16#include <cpupower.h>
 17
 18#include "config.h"
 19#include "system.h"
 20
 21/**
 22 * returns time since epoch in µs
 23 *
 24 * @retval time
 25 **/
 26
 27long long int get_time()
 28{
 29	struct timeval now;
 30
 31	gettimeofday(&now, NULL);
 32
 33	return (long long int)(now.tv_sec * 1000000LL + now.tv_usec);
 34}
 35
 36/**
 37 * sets the cpufreq governor
 38 *
 39 * @param governor cpufreq governor name
 40 * @param cpu cpu for which the governor should be set
 41 *
 42 * @retval 0 on success
 43 * @retval -1 when failed
 44 **/
 45
 46int set_cpufreq_governor(char *governor, unsigned int cpu)
 47{
 48
 49	dprintf("set %s as cpufreq governor\n", governor);
 50
 51	if (cpupower_is_cpu_online(cpu) != 1) {
 52		perror("cpufreq_cpu_exists");
 53		fprintf(stderr, "error: cpu %u does not exist\n", cpu);
 54		return -1;
 55	}
 56
 57	if (cpufreq_modify_policy_governor(cpu, governor) != 0) {
 58		perror("cpufreq_modify_policy_governor");
 59		fprintf(stderr, "error: unable to set %s governor\n", governor);
 60		return -1;
 61	}
 62
 63	return 0;
 64}
 65
 66/**
 67 * sets cpu affinity for the process
 68 *
 69 * @param cpu cpu# to which the affinity should be set
 70 *
 71 * @retval 0 on success
 72 * @retval -1 when setting the affinity failed
 73 **/
 74
 75int set_cpu_affinity(unsigned int cpu)
 76{
 77	cpu_set_t cpuset;
 78
 79	CPU_ZERO(&cpuset);
 80	CPU_SET(cpu, &cpuset);
 81
 82	dprintf("set affinity to cpu #%u\n", cpu);
 83
 84	if (sched_setaffinity(getpid(), sizeof(cpu_set_t), &cpuset) < 0) {
 85		perror("sched_setaffinity");
 86		fprintf(stderr, "warning: unable to set cpu affinity\n");
 87		return -1;
 88	}
 89
 90	return 0;
 91}
 92
 93/**
 94 * sets the process priority parameter
 95 *
 96 * @param priority priority value
 97 *
 98 * @retval 0 on success
 99 * @retval -1 when setting the priority failed
100 **/
101
102int set_process_priority(int priority)
103{
104	struct sched_param param;
105
106	dprintf("set scheduler priority to %i\n", priority);
107
108	param.sched_priority = priority;
109
110	if (sched_setscheduler(0, SCHEDULER, &param) < 0) {
111		perror("sched_setscheduler");
112		fprintf(stderr, "warning: unable to set scheduler priority\n");
113		return -1;
114	}
115
116	return 0;
117}
118
119/**
120 * notifies the user that the benchmark may run some time
121 *
122 * @param config benchmark config values
123 *
124 **/
125
126void prepare_user(const struct config *config)
127{
128	unsigned long sleep_time = 0;
129	unsigned long load_time = 0;
130	unsigned int round;
131
132	for (round = 0; round < config->rounds; round++) {
133		sleep_time +=  2 * config->cycles *
134			(config->sleep + config->sleep_step * round);
135		load_time += 2 * config->cycles *
136			(config->load + config->load_step * round) +
137			(config->load + config->load_step * round * 4);
138	}
139
140	if (config->verbose || config->output != stdout)
141		printf("approx. test duration: %im\n",
142		       (int)((sleep_time + load_time) / 60000000));
143}
144
145/**
146 * sets up the cpu affinity and scheduler priority
147 *
148 * @param config benchmark config values
149 *
150 **/
151
152void prepare_system(const struct config *config)
153{
154	if (config->verbose)
155		printf("set cpu affinity to cpu #%u\n", config->cpu);
156
157	set_cpu_affinity(config->cpu);
158
159	switch (config->prio) {
160	case SCHED_HIGH:
161		if (config->verbose)
162			printf("high priority condition requested\n");
163
164		set_process_priority(PRIORITY_HIGH);
165		break;
166	case SCHED_LOW:
167		if (config->verbose)
168			printf("low priority condition requested\n");
169
170		set_process_priority(PRIORITY_LOW);
171		break;
172	default:
173		if (config->verbose)
174			printf("default priority condition requested\n");
175
176		set_process_priority(PRIORITY_DEFAULT);
177	}
178}
179