From: Arjan van de Ven <arjan@infradead.org>
To: markh@compro.net
Cc: "linux-os (Dick Johnson)" <linux-os@analogic.com>,
Jan Engelhardt <jengelh@medozas.de>,
"Kok, Auke" <auke-jan.h.kok@intel.com>,
"solsTiCe d'Hiver" <solstice.dhiver@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: PROBLEM: no cpu MHz in /proc/cpuinfo on 2.6.25.4-rt6
Date: Wed, 11 Jun 2008 14:28:40 -0700 [thread overview]
Message-ID: <20080611142840.47d65782@infradead.org> (raw)
In-Reply-To: <48503EB9.6000606@compro.net>
On Wed, 11 Jun 2008 17:08:09 -0400
Mark Hounschell <markh@compro.net> wrote:
> >
> > btw you also changed the problem from "what is the cpu frequency" to
> > "how usable is rdtsc for time". My entire point was that these
> > weren't related...
> >
> >
>
> If they are not the same how do you know at what rate the tsc is
> counting.
it's not ticking at the cpu frequency as general rule.
For current cpus, your best bet is to calibrate against some external
time source... it'll stay constant after that, unless you go to idle,
then it may or may not stop (or both). For older cpus it'll change with
frequency changes.
--
If you want to reach me at my work email, use arjan@linux.intel.com
For development, discussion and tips for power savings,
visit http://www.lesswatts.org
next prev parent reply other threads:[~2008-06-11 21:28 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-10 19:52 solsTiCe d'Hiver
2008-06-10 20:13 ` Arjan van de Ven
2008-06-10 20:42 ` Kok, Auke
2008-06-11 12:42 ` Jan Engelhardt
2008-06-11 13:36 ` Arjan van de Ven
2008-06-11 13:52 ` Jan Engelhardt
2008-06-11 13:58 ` Arjan van de Ven
2008-06-11 14:14 ` linux-os (Dick Johnson)
2008-06-11 15:10 ` Peter Zijlstra
2008-06-11 15:36 ` Arjan van de Ven
2008-06-11 16:59 ` Mark Hounschell
2008-06-11 17:44 ` Arjan van de Ven
2008-06-11 17:54 ` Mark Hounschell
2008-06-11 20:29 ` Arjan van de Ven
2008-06-11 20:37 ` Mark Hounschell
2008-06-11 20:55 ` Arjan van de Ven
2008-06-11 20:59 ` Mark Hounschell
2008-06-11 20:58 ` Arjan van de Ven
2008-06-11 21:08 ` Mark Hounschell
2008-06-11 21:28 ` Arjan van de Ven [this message]
2008-06-11 21:39 ` Chris Friesen
2008-06-11 23:08 ` Andi Kleen
2008-06-11 16:08 ` Ray Lee
2008-06-11 16:32 ` Arjan van de Ven
2008-06-11 12:40 ` Jan Engelhardt
2008-06-11 14:15 ` solsTiCe d'Hiver
2008-06-11 14:36 ` Jan Engelhardt
2008-06-11 15:35 ` solsTiCe d'Hiver
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