From: "Alexei A. Frounze" <dummy_addressee AT hotmail DOT com>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Any comments about using RDTSC to sync code ?
Date: Sun, 1 Apr 2001 00:45:53 -0500
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

"Tom St Denis" <tomstdenis AT yahoo DOT com> wrote in message
news:O1zx6.177142$p66 DOT 52247228 AT news3 DOT rdc1 DOT on DOT home DOT com...
>
> "Eduardo TUDA Lorenzetti Pellini" <dochell AT MailAndNews DOT com> wrote in
message
> news:3ACABB23 AT MailAndNews DOT com...
> >
> > The second problem is that (i think) PC hardware don't have any
> > stabilization
> > method for the CPU internal clock (Xtal voltage and temperature
> regulation).
> > So i think that the CPU clock may vary, but i don't know how much.
>
> Typically it's about 10%.  My athlon 1200mhz runs at "supposedly" 1211mhz
> according to various programs.

"Vary at runtime" is not a difference between the average CPU speed and the
label sticked on the chip...

> Using RDTSC to sync programs is a bad idea since RDTSC may take a variable
> amount of cycles to complete.

Why?

Good Luck
--
Alexei A. Frounze
alexfru [AT] chat [DOT] ru
http://alexfru.chat.ru
http://members.xoom.com/alexfru/
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