获取机器当前CPU频率

拼搏现实的明天。 2022-05-19 00:16 184阅读 0赞

###                                         ** 获取机器当前CPU频率** ###

struct perf\_cpu\_info  
\{  
    int tsc;  
    int index;  
    int mhz;  
\};  
struct perf\_cpu\_info \*cpu\_list;

static unsigned long long native\_read\_tsc(void)  
\{  
    unsigned long long val;  
    asm volatile("rdtsc": "=A" (val));  
    return val;  
\}

unsigned int calibrate\_tsc(void)  
\{  
    unsigned long long val;  
    unsigned long long val2;  
    long long diff = 0;  
    int error = 0,cnt = 0;  
    unsigned long long min\_tsc = (unsigned long long) -1;  
    val = native\_read\_tsc();  
    do \{  
        usleep(4950);  
        val2 =native\_read\_tsc();  
        diff = val2 - val;  
        if (diff > 0) \{  
            min\_tsc = min\_tsc > diff?diff:min\_tsc;  
            error = 0;  
            cnt ++;  
        \}  
        if (error ++ > 6) return -1;  
        val = val2;  
    \} while(cnt < 3);

return min\_tsc / 5;  
\}

int aperfmperf\_mhz(unsigned int cpu, unsigned int tsc)  
\{  
    unsigned long long aperf = 0, aperf2 = 0;  
    unsigned long long mperf = 0, mperf2 = 0;

if (rdmsr\_on\_cpu(MSR\_IA32\_MPERF, cpu, &mperf) != 0)  
        return -1;

if (rdmsr\_on\_cpu(MSR\_IA32\_APERF, cpu, &aperf) != 0)  
        return -1;  
    usleep(99950);  
    if (rdmsr\_on\_cpu(MSR\_IA32\_MPERF, cpu, &mperf2) != 0)  
        return -1;

if (rdmsr\_on\_cpu(MSR\_IA32\_APERF, cpu, &aperf2) != 0)  
        return -1;

aperf = aperf2 - aperf;  
    mperf = mperf2 - mperf;  
    return tsc \* aperf / mperf / 1000;  
\}

void\* threadFun(void\* arg)  //arg  传递线程标号（自己定义）  
\{  
    cpu\_set\_t mask;  //CPU核的集合  
    cpu\_set\_t get;   //获取在集合中的CPU  
    struct perf\_cpu\_info \*perf = (struct perf\_cpu\_info \*)arg;

CPU\_ZERO(&mask);  
    CPU\_SET(perf->index, &mask);  
    if (sched\_setaffinity(0, sizeof(mask), &mask) == -1)  
    \{  
         printf("warning: could not set CPU affinity, continuing...\\n");  
    \}  
    perf->mhz = aperfmperf\_mhz(perf->index, perf->tsc);  
//    printf("cpu\[%d\] %d Mhz\\n", perf->index, perf->mhz);

return NULL;  
\}

int aperf\_get\_min\_freq\_mhz(int tsc)  
\{  
    int num=0;  
    int i;

num = sysconf(\_SC\_NPROCESSORS\_CONF);  //获取核数  
    pthread\_t thread\[num\];

cpu\_list = (struct perf\_cpu\_info\*)malloc(num \* sizeof (struct perf\_cpu\_info));  
    for(i=0;i<num;i++)  
    \{  
        cpu\_list\[i\].tsc = tsc;  
        cpu\_list\[i\].index = i;  
        pthread\_create(&thread\[i\],NULL,threadFun,(void\*)&cpu\_list\[i\]);  
    \}  
    unsigned int min = (unsigned int)(-1);  
    for(i=0; i< num; i++)  
    \{  
        pthread\_join(thread\[i\],NULL);//等待所有的线程结束，线程为死循环所以CTRL+C结束  
    \}  
    for(i=0; i< num; i++)  
    \{  
        min = cpu\_list\[i\].mhz < min ? cpu\_list\[i\].mhz : min;  
    \}

free(cpu\_list);  
    return min;  
\}