Re: Counting the clock cycles

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From
Andrei Cojocaru <spinlock_lists@empirequest.com>
Date
17 Jul 2002 13:35:31
Subject
Re: Counting the clock cycles
Message-ID
005f01c22dd1$7be7d180$0300a8c0@fivehundred


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I am already synchronizing using xntp, that's not the problem. The problem is by some weird way the clock got out of sync by about 1hr during daylight switch on one of the computers I run, and I need a reliable way to get passage of time (I don't need date/time, just the passage of it) for different internal operations in the program.
----- Original Message -----
From: "Darren Pilgrim" <dmp@pantherdragon.org>
To: "Andrei Cojocaru" <spinlock_lists@empirequest.com>
Cc: "Cy Schubert - CITS Open Systems Group" <Cy.Schubert@uumail.gov.bc.ca>; <freebsd-hackers@FreeBSD.ORG>
Sent: Wednesday, July 17, 2002 14:25
Subject: Re: Counting the clock cycles


> Andrei Cojocaru wrote:
> >
> > doesn't fit my criteria since it changes, bah I'll just use
> > gettimeofday since it's a portable API and hope the computers I run
> > it on don't change their blocks by too much...
>
> If you're really worried about it, get a GPS device that can provide
> you with a PPS signal for use with ntpd. Then I'd say you could safely
> rely on the computer's clock being accurate.
>
> > From: "Cy Schubert - CITS Open Systems Group" <Cy.Schubert@uumail.gov.bc.ca>
> > > In message <00d501c22dc4$57d08b00$0200a8c0@twothousand>, "Andrei
> > > Cojocaru" writes:
> > > > I was asking around in #freebsdhelp on EFNet what the equivalent of
> > > > GetTickCount() in the Win32 API is in FreeBSD.
> > > >
> > > > I need a way to properly determine passage of time that is not affected if I
> > > > change the system clock for example. The only way I'm aware that you can do
> > > > that is by counting the number of clock cycles since system startup. What
> > > > function does that in FreeBSD? I'd also like a Linux way if possible. (that
> > > > is a way that will work across all UNIX clones). Thanks and please include
> > > > my email in the reply directly since I'm not signed up to this mailing list.
> > > > Thanks once again.
> > >
> > > How about time(3)?
>

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