RE: [GD-Windows] More timer fun!

[Tom F. <to...@mu...>]

There's the fourth method that someone suggested - set up a silent sound of
known length, and play it on your sound card. And have a notification at the
end of each cycle. And now you have a medium-term calibrator for
timeGetTime()'s slow drifts. Very very hacky, but suprisingly accurate, even
on cheapo sound cards.

Of course, many of them don't support notifications, so...


Tom Forsyth - purely hypothetical Muckyfoot bloke.

This email is the product of your deranged imagination,
and does not in any way imply existence of the author.

> -----Original Message-----
> From: Jon Watte [mailto:hp...@mi...]
> Sent: 02 September 2002 19:56
> To: Grills, Jeff; gam...@li...
> Subject: RE: [GD-Windows] More timer fun! 
> 
> 
> 
> > and that we can apparently fix this within our games with 
> enough work,
> > Microsoft should integrate fixes for this into their current and 
> > past OS's.
> 
> QueryPerformanceCounter() is slow enough already (on the order of 1 
> microsecond because of the bus transaction involved). Fixing it is 
> decidedly non-trivial, and, at a minimum, requires doubling the cost 
> of calling it. I think most people who use these functions would 
> rather not take the additional cost hit.
> 
> RDTSC doesn't skip, that I've heard of. It's absolutely the right 
> thing to use for profiling and similar measurements. The only 
> weakness of it is that it may not measure wall-clock time accurately 
> on laptops (that use TimeStep CPUs). I'm prepared to live with that 
> on a local scale, and to use an unholy heuristic trio of 
> QPC/timeGetTime()/RDTSC for keeping track of wallclock time on a 
> global scale.
> 
> Cheers,
> 
> 				/ h+
> 
> 
> 
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