accurate timing in linux?

Everything Unix Technical

Started by colinisinhere August 29, 2005 02:23 AM

3 comments, last by Generic Guest 19 years, 3 months ago

colinisinhere

Author

100

August 29, 2005 02:23 AM

I looked into how timing can be done in linux/unix and I ran into this function:


unsigned int getMilliSeconds() {
    struct timeb tb;
    ftime(&tb);
    return tb.time * 1000 + tb.millitm;
}

Is there a more accurate way of achiving this?

markr

1,692

August 29, 2005 03:59 AM

According to the man page,

Quote:
This function is obsolete. Don't use it. If the time in seconds suffices, time(2) can be used; gettimeofday(2) gives microseconds; clock_gettime(3) gives nanoseconds but is not yet widely available.

gettimeofday is normally the preferred function. It's accurate to 1us on most systems, which is typically enough for games.

Mark

NicoDeLuciferi

168

August 29, 2005 10:32 AM

like markr said, gettimeofday is the function for you.

like so:

double getAccurateTimeInSeconds(){  struct timeval tm;  struct timezone tz;  gettimeofday(&tm, &tz);  return (double)(tm.tv_sec) + ((double)(tm.tv_usec) * 0.000001);}