RE: [boost] Re: date_time high resolution clock for Win32

From: Reid Sweatman (drunkardswalk_at_[hidden])
Date: 2004-05-19 00:00:29

> -----Original Message-----
> From: boost-bounces_at_[hidden] 
> [mailto:boost-bounces_at_[hidden]] On Behalf Of Aaron W. 
> LaFramboise
> Sent: Tuesday, May 18, 2004 8:12 PM
> To: boost_at_[hidden]
> Subject: Re: [boost] Re: date_time high resolution clock for Win32
> 
> 
> Reid Sweatman wrote:
> 
> >Hardware is definitely involved, and it makes any method 
> based on the Time
> >Stamp Counter not nearly as accurate as you might think.  
> It's all been
> >hashed out here before, so rather than repeat it all, I'll 
> just give you the
> >reference.  Look back through the Boost Archives for 1999 
> for a thread
> >called "timer classes" with my name and that of Andy Glew 
> associated with
> >it, and you'll find some very interesting information 
> (mainly from Andy, who
> >was involved with the silicon design).  
> >
> >Reid Sweatman
> >  
> >
> I found the thread at 
> http://aspn.activestate.com/ASPN/Mail/Browse/Threaded/boost/11
> 37286 .  
> It is very informative; thank you for the information.
> 
> I also found an interesting URL by someone who has done some similar 
> research on timing in Windows, 
> http://www.wideman-one.com/gw/tech/dataacq/wintiming.htm.  
> Unfortunately, most of this is largely inapplicable in Boost.
> 
> It still seems to me that, despite its flaws, Intel's RDTSC combined 
> with a time source assumed to be relatively reliable, such as the system 
> clock, could yield a hybrid clock no worse than the primary system 
> clock  The improvement in accuracy might benefit some applications, and 
> probably wouldn't hurt.
> 
> In any case, there should be no illusions that any timer setup on 
> Windows will meet hard real-time constraints.  In fact, even if there 
> were some other timer available that did not share these problems, it is 
> quite likely it would not offer realistically improved performance 
> anyway due to Windows scheduling.  With whatever might be implemented 
> for Boost, this needs to be documented.

I agree, it can, and I've used it for most of my applications, including two
games.  So long as you don't have unrealistic expectations, it's quite
useful.

Reid Sweatman