From: Mark Hounschell <markh@compro.net>
To: Arjan van de Ven <arjan@infradead.org>
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 17:08:09 -0400 [thread overview]
Message-ID: <48503EB9.6000606@compro.net> (raw)
In-Reply-To: <20080611135828.29f6a7d7@infradead.org>
Arjan van de Ven wrote:
> On Wed, 11 Jun 2008 16:37:38 -0400
> Mark Hounschell <markh@compro.net> wrote:
>
>>> Mark
>>>
>> Ok, what would one use besides the tsc to take a fast high-res time
>> stamp in a kernel module that could also be used in user land (same
>> time source) to for instance calculate the the time between an event
>> in the kernel to an event in user land?
>>
>> do_gettimeofday / gettimeofday are not really acceptable.
>
>
> 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.
But back to "how usable is rdtsc for time", is there a
clock_gettime(CLOCK_MONOTONIC, &time) equivalent that can be used in the kernel?
Mark
next prev parent reply other threads:[~2008-06-11 21:09 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-10 19:52 PROBLEM: no cpu MHz in /proc/cpuinfo on 2.6.25.4-rt6 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 [this message]
2008-06-11 21:28 ` Arjan van de Ven
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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