From: "H. Peter Anvin" <hpa@zytor.com>
To: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: john stultz <johnstul@us.ibm.com>,
Brian Bloniarz <bmb@athenacr.com>, Ingo Molnar <mingo@elte.hu>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Andi Kleen <andi@firstfloor.org>,
Arjan van de Ven <arjan@infradead.org>,
Venkatesh Pallipadi <venki@google.com>,
chris.mason@oracle.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86: Export tsc related information in sysfs
Date: Mon, 24 May 2010 11:19:56 -0700 [thread overview]
Message-ID: <4BFAC34C.5020606@zytor.com> (raw)
In-Reply-To: <ce764b91-11b0-44a5-9cf9-96977652bbd5@default>
On 05/24/2010 11:13 AM, Dan Magenheimer wrote:
> Just wondering: If one were to put an ultra-precise scope on
> a processor, how far off would the calibrated value be? I'd
> imagine the process of calibrating one unknown crystal against
> a second crystal which has a known-but-not-highly-precise
> frequency, though good enough for most purposes, is not particularly
> accurate. In other words, maybe the stamped rate is more accurate
> than the calibrated rate anyway?
No. Not even close.
A spread-spectrum clock is inaccurate by entire percentage points.
A non-spread clock is typically ±50 ppm with typical consumer PC
oscillators, ±1 ppm with non-crappy but still cheap oscillators (e.g.
used in cell phones.)
-hpa
next prev parent reply other threads:[~2010-05-24 18:24 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-20 19:19 [PATCH] x86: Export tsc related information in sysfs Brian Bloniarz
2010-05-22 2:03 ` john stultz
2010-05-22 3:33 ` H. Peter Anvin
2010-05-24 18:13 ` Dan Magenheimer
2010-05-24 18:19 ` H. Peter Anvin [this message]
2010-05-24 18:51 ` john stultz
2010-05-24 20:20 ` H. Peter Anvin
2010-05-24 20:39 ` john stultz
2010-05-24 21:26 ` H. Peter Anvin
2010-05-24 22:04 ` Dan Magenheimer
2010-05-24 22:30 ` H. Peter Anvin
2010-05-24 22:49 ` john stultz
2010-05-24 23:16 ` Dan Magenheimer
2010-05-24 23:19 ` H. Peter Anvin
2010-05-24 23:30 ` john stultz
2010-05-24 23:42 ` Andi Kleen
2010-05-25 0:01 ` Dan Magenheimer
2010-05-25 0:07 ` H. Peter Anvin
2010-05-25 1:33 ` Brian Bloniarz
2010-05-26 0:16 ` Brian Bloniarz
2010-05-26 0:48 ` john stultz
2010-05-26 2:50 ` Brian Bloniarz
2010-05-26 12:35 ` Thomas Gleixner
2010-05-26 14:26 ` Dan Magenheimer
2010-05-26 14:41 ` Thomas Gleixner
2010-05-26 15:04 ` john stultz
2010-05-26 16:02 ` Brian Bloniarz
2010-05-26 16:25 ` john stultz
2010-05-26 18:24 ` H. Peter Anvin
2010-05-26 18:44 ` Brian Bloniarz
2010-05-26 18:51 ` H. Peter Anvin
2010-05-26 20:19 ` john stultz
2010-05-26 21:06 ` H. Peter Anvin
2010-05-26 19:49 ` john stultz
2010-05-26 20:22 ` Brian Bloniarz
2010-05-26 12:30 ` Thomas Gleixner
-- strict thread matches above, loose matches on Subject: below --
2010-05-15 1:40 Venkatesh Pallipadi
2010-05-15 9:57 ` Andi Kleen
2010-05-15 13:29 ` Dan Magenheimer
2010-05-15 16:48 ` Venkatesh Pallipadi
2010-05-15 19:14 ` Arjan van de Ven
2010-05-15 22:32 ` Dan Magenheimer
2010-05-16 5:43 ` Arjan van de Ven
2010-05-16 9:20 ` Thomas Gleixner
2010-05-16 16:42 ` Dan Magenheimer
2010-05-16 19:14 ` Thomas Gleixner
2010-05-17 1:31 ` Dan Magenheimer
2010-05-17 5:06 ` Arjan van de Ven
2010-05-18 9:58 ` Peter Zijlstra
2010-05-18 10:03 ` Peter Zijlstra
2010-05-18 11:25 ` Andi Kleen
2010-05-18 11:58 ` Peter Zijlstra
2010-05-18 15:13 ` Dan Magenheimer
2010-05-18 16:40 ` H. Peter Anvin
2010-05-18 16:52 ` Peter Zijlstra
2010-05-18 17:04 ` H. Peter Anvin
2010-05-18 17:49 ` Dan Magenheimer
2010-05-18 18:46 ` H. Peter Anvin
2010-05-18 19:00 ` Dan Magenheimer
2010-05-18 19:16 ` Dan Magenheimer
2010-05-18 19:26 ` H. Peter Anvin
2010-05-18 20:29 ` Dan Magenheimer
2010-05-18 20:34 ` H. Peter Anvin
2010-05-18 21:02 ` Dan Magenheimer
2010-05-18 21:13 ` Andi Kleen
2010-05-19 6:26 ` Peter Zijlstra
2010-05-17 10:20 ` Thomas Gleixner
2010-05-16 20:29 ` Arjan van de Ven
2010-05-17 10:26 ` Andi Kleen
2010-06-04 14:24 ` Pavel Machek
2010-05-15 22:45 ` Thomas Gleixner
2010-05-17 10:22 ` Andi Kleen
2010-05-17 15:23 ` Dan Magenheimer
2010-05-17 16:56 ` Andi Kleen
2010-05-17 22:36 ` Thomas Gleixner
2010-05-17 23:33 ` Dan Magenheimer
2010-05-18 0:00 ` Ingo Molnar
2010-05-18 0:02 ` Ingo Molnar
2010-05-15 12:35 ` Jaswinder Singh Rajput
2010-05-15 14:37 ` Venkatesh Pallipadi
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