tools/power/cpupower/bench/system.c

Source file repositories/reference/linux-study-clean/tools/power/cpupower/bench/system.c

File Facts

System
Linux kernel
Corpus path
tools/power/cpupower/bench/system.c
Extension
.c
Size
3630 bytes
Lines
180
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-or-later
/*  cpufreq-bench CPUFreq microbenchmark
 *
 *  Copyright (C) 2008 Christian Kornacker <ckornacker@suse.de>
 */

#include <stdio.h>
#include <time.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>

#include <sched.h>

#include <cpufreq.h>
#include <cpupower.h>

#include "config.h"
#include "system.h"

/**
 * returns time since epoch in µs
 *
 * @retval time
 **/

long long int get_time()
{
	struct timeval now;

	gettimeofday(&now, NULL);

	return (long long int)(now.tv_sec * 1000000LL + now.tv_usec);
}

/**
 * sets the cpufreq governor
 *
 * @param governor cpufreq governor name
 * @param cpu cpu for which the governor should be set
 *
 * @retval 0 on success
 * @retval -1 when failed
 **/

int set_cpufreq_governor(char *governor, unsigned int cpu)
{

	dprintf("set %s as cpufreq governor\n", governor);

	if (cpupower_is_cpu_online(cpu) != 1) {
		perror("cpufreq_cpu_exists");
		fprintf(stderr, "error: cpu %u does not exist\n", cpu);
		return -1;
	}

	if (cpufreq_modify_policy_governor(cpu, governor) != 0) {
		perror("cpufreq_modify_policy_governor");
		fprintf(stderr, "error: unable to set %s governor\n", governor);
		return -1;
	}

	return 0;
}

/**
 * sets cpu affinity for the process
 *
 * @param cpu cpu# to which the affinity should be set
 *
 * @retval 0 on success
 * @retval -1 when setting the affinity failed
 **/

int set_cpu_affinity(unsigned int cpu)
{
	cpu_set_t cpuset;

	CPU_ZERO(&cpuset);
	CPU_SET(cpu, &cpuset);

	dprintf("set affinity to cpu #%u\n", cpu);

	if (sched_setaffinity(getpid(), sizeof(cpu_set_t), &cpuset) < 0) {
		perror("sched_setaffinity");
		fprintf(stderr, "warning: unable to set cpu affinity\n");
		return -1;
	}

	return 0;

Annotation

Implementation Notes