Re: strange nonmonotonic behavior of gettimeoftheday

[Manfred Spraul]

>
> on AMD K6, VIA Technologies VT 82C586, Compaq Presario XL119. 
> [snip]
> gives following result on box in question 
> root@******:# ./clo 
> Leap found: -1687 msec 
> and prints nothing on all other my boxes. 

Perhaps APM or SMI problems?
Could you run the attached program?

--
        Manfred
#include <stdio.h>
#include <sys/time.h>
#include <unistd.h>
#include <time.h>

static unsigned long long get_tsc(void)
{
        unsigned long v1;
        unsigned long v2;
        __asm__ __volatile__(
                "rdtsc\n\t"
                : "=a" (v1), "=d" (v2));
        return (((unsigned long long)v2)<<32)+v1;
}

int main(int argc, char** argv)
{
        unsigned long long t1;
        unsigned long long t2;

        printf("RDTSC tester\n");
        t1 = get_tsc();
        for(;;) {
                t2 = get_tsc();
                if(t1 > t2) {
                        printf("tsc jumped backwards: from %lld to %lld.\n",
                                        t1, t2);
                }
#if 0
                printf("diff is %lld-%lld=%d.\n",t2,t1,t2-t1);
#endif
                t1 = t2;
        
        }
        return 1;
}