Linux在操作系统下实时定时器posix_timer
其实Linux还有一种高精度定时器，即posix_timer.原则上，它也可以用于变频rdtsc指令，因为CPU我们也知道频率，内核也知道变频。
下面是我的timer_create例子在编译时应添加rt库，这是linux的realtime库：
gcc -o test test.c
#include
#include
#include
#include
#include
#define rdtsc(low,high) __asm__ __volatile__("rdtsc" : "=a" (low),"=d" (high))
timer_t tt;
void handler (int sig,siginfo_t * extra,void *cruft)
...{
static last_i=0;
unsigned int i,j;
rdtsc(i,j);
printf ("time:%u,%u,[%u] %uHZ ",j,i,i-last_i,(i-last_i)*10/1000000);
last_i = i;
}
int main ()
...{
int i=0;
sigset_t sigset;
sigfillset (&sigset);
sigdelset (&sigset,SIGRTMIN);
sigprocmask (SIG_SETMASK,&sigset,NULL);
struct sigaction sa;
sigfillset (&sa.sa_mask);
sa.sa_flags = SA_SIGINFO;
sa.sa_sigaction = handler;
if (sigaction (SIGRTMIN,&sa,NULL) < 0)
...{
perror ("sigaction failed ");
exit (-1);
}
struct sigevent timer_event;
struct itimerspec timer;
timer.it_interval.tv_sec = 0;
timer.it_interval.tv_nsec = 100 * 1000 * 1000;
timer.it_value = timer.it_interval;
timer_event.sigev_notify = SIGEV_SIGNAL;
timer_event.sigev_signo = SIGRTMIN;
timer_event.sigev_value.sival_ptr = (void *) &tt;
if (timer_create (CLOCK_REALTIME,&timer_event,&tt) < 0)
...{
perror ("timer_create failed");
exit (-1);
}
if (timer_settime (tt,0,&timer,NULL) < 0)
...{
perror ("timer_settime failed");
exit (-1);
}
while (i < 10)
...{
pause ();
}
return 0;
}
输出结果：
time:166081,1934350847,[1934350847] 2163HZ
time:166081,2120528291,[186177444] 1861HZ
time:166081,2306679576,[186151285] 1861HZ
time:166081,2494695630,[188016054] 1880HZ
time:166081,2680865389,[186169759] 1861HZ
time:166081,2867018473,[186153084] 1861HZ
time:166081,3053152230,[186133757] 1861HZ
time:166081,3239309935,[186157705] 1861HZ
time:166081,3425467261,[186157326] 1861HZ
time:166081,3611639266,[186172005] 1861HZ
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