[boost] Re: timer classes

From: Reid Sweatman (reids_at_[hidden])
Date: 1999-07-01 15:05:34

Well, the classes I've been using for my own stuff aren't templates, so
they're not generic.  If that's not a problem, I don't mind showing them.
They're a couple of years old, and need a bit of work (particularly a method
for determining system clock speed, which at present is a parameter).  I've
been meaning to add in something like Intel's clock-speed determiner, but
never had the time.

> -----Original Message-----
> From: Beman Dawes [mailto:beman_at_[hidden]]
> Sent: Thursday, July 01, 1999 12:48 PM
> To: boost_at_[hidden]; 'boost_at_[hidden]'
> Subject: [boost] Re: timer classes
> 
> 
> At 11:37 AM 7/1/99 -0700, Reid Sweatman wrote:
> 
> >Just a minor cavil from someone who does most of his programming on
> Wintel
> >platforms:  the C and system timer functions aren't very reliable,
> because
> >they're at the mercy of the time-share schemes (which are different
> in every
> >version of Windows), and don't return very reliable numbers.  On
> Pentium and
> >better Intel processors, though, the Time-stamp instructions are
> available,
> >which directly read an _Int64 counter in the CPU that counts cycles
> since
> >start-up or reset.  The only inaccuracies in using these
> instructions are
> >those associated with the function-call overhead, assuming you've
> handled
> >thread-locking and such correctly.  Admittedly, this only works on a
> subset
> >of one brand of processor, but realistically it accounts for a large
> chunk
> >of market share.  I'd rather see such a version of the
> implementation layer
> >for Pentium systems than one that uses the standard system calls.
> 
> I never doubted that a timer implementation based on <ctime> isn't
> going to be very accurate on some platforms; the current
> implementation can be viewed as the default when nothing better is
> available.  So please do contribute better implementations for
> particular hardware and/or compilers.  Here is your chance to get
> your picture posted on the boost web site!
> 
> --Beman
> 
> 
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