Skip site navigation (1)Skip section navigation (2)
Date:      Tue, 01 May 2001 02:08:07 -0700
From:      Terry Lambert <tlambert2@mindspring.com>
To:        Mike Smith <msmith@FreeBSD.ORG>
Cc:        Terry Lambert <tlambert@primenet.com>, Rolf Neugebauer <neugebar@dcs.gla.ac.uk>, freebsd-alpha@FreeBSD.ORG
Subject:   Re: determine cycle counter frequency in user space
Message-ID:  <3AEE7CF7.69D87D5F@mindspring.com>
References:  <200104302157.f3ULvvv02259@mass.dis.org>

next in thread | previous in thread | raw e-mail | index | archive | help
Mike Smith wrote:
> Use time_second for coarse timing requirements.

[ ... ]

> The cycle counter can't be relied on.  Get this through your
> thick head.  The clock frequency on many Alpha systems is
> unstable, and on most PCs, it can change out from under you
> with no warning.

[ ... ]

> Hardware sucks; what can I say?  You can't do this usefully
> in userspace; stop trying and go buy some real timing hardware
> if you actually care.

Sorry; I didn't get this message in time.

Unfortunately, my code is now working with ~90uS accuracy,
+/- 90uS.

I'll try to be more dilligent in keeping up with my email
from now on... ;-).

-- Terry

To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-alpha" in the body of the message




Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?3AEE7CF7.69D87D5F>