From:	"Alexei A. Frounze" <dummy_addressee AT hotmail DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Reading MSR (Athlon multiplier)
Date:	Thu, 18 Jan 2001 18:34:39 -0500
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"Lasse Kärkkäinen / Tronic" <tronic2 AT sci DOT fi DOT don'tSPAMmeBUTremoveTHIS> wrote
in message news:3a6775dd DOT 9880436 AT news DOT sci DOT fi...
> Yep. That's not a problem, because I'm develeloping a benchmark for
> DOS-use.

The thing is that if there is some code that executes upon timer interrupt
or another interrupt happens inbetween tick waiting loop and RDTSC, we have
an incorrect value. And the more code is there, the more error. This way, if
you have drivers like SMARTDRV, RTC may be useless until you flush the disk
cache completely. And this is worsen under windows by other things.

> What do you think, could I get more accurate times by using RTC
> (instead of Allegro's timer) and a bit longer period?
>
> Allegro's timer almost stops on alt-tab -switch to another window.

Don't do "Alt-Tab" :)

> I still need to read MSR, do you (or anyone else) happen to know how
> to?

I haven't used that thing yet. Just RDTSC. But you may want to read intel
architecture software developer's manual (3 volumes) available on intel
site.

Good Luck
--
Alexei A. Frounze
alexfru [AT] chat [DOT] ru
frounze [AT] ece [DOT] rochester [DOT] edu
http://alexfru.chat.ru
http://members.xoom.com/alexfru/
http://welcome.to/pmode/

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