cpufrequency.c

cpufrequency.c

#include <errno.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>

#include <sys/sysctl.h>

int main() {
    static const char* NAMES[3] = {
        "hw.cpufrequency",
        "hw.cpufrequency_min",
        "hw.cpufrequency_max",
    };
    for (int i = 0; i < 3; ++i) {
        int64_t value = -1;
        size_t len = sizeof(value);
        printf("%s: ", NAMES[i]);
        if (0 == sysctlbyname(NAMES[i], &value, &len, NULL, 0)) {
            printf("%lld\n", (long long)value);
        } else if (ENOENT == errno) {
            printf("error: 'unknown value'\n");
        } else {
            printf("error: '%s'\n", strerror(errno));
        }
    }
    return 0;
}