QNX. do some research on that OS. Long time ago I heard that it was a
real time OS and that programming and running programs on it was VERY
much more accurate than the standard INTEL. I don't really know what you
want... if you wan precission then this might be your solution... if you
dont... then try the bes aproximation possible and use it...
El jue, 12-06-2003 a las 03:38, Ray Olszewski escribió:
> At 08:17 PM 6/11/2003 -0400, Mark Hahn wrote:
> > > An i386 has a hardware timer that beats about 72 times per second, leaving
> >
> >well, it has several hardware counter/timers, but that setting
> >is not special (and isn't it only used by DOS?)
>
> Actually, I wrote that from memory (of timer limitations I encountered when
> programming in VB on Windows 2000), and I think I got the actual numbers wrong.
>
> > > me uncertain as to how accurate timings below 14 msec can be on this
> > > hardware using the kernel's internal timer.
> >
> >timers can be set MUCH faster than that.
>
> In principle, yes. usleep() timers can be *set* to 1 usec. That's not the
> question. The question is how *accurate* timers based on usleep() can be at
> low settings.
>
> This experiment says they are not very accurate. I changed Lee's loop to be:
>
> for(i = 0; i < 500; i++)
> {
> usleep(10);
> }
>
> Now 500 x 10 = 5000 usec, or 1/200 seconds. But the loop actually takes 10
> seconds to iterate. This implies that usleep() has a minimum delay of
> 10/500 seconds, or 20 msec, built into it (at least on my test system).
>
> My best guess is that this limitation derives either from the timer code in
> the Linux kernel or from the system hardware that code relies on.
>
>
>
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