Re: Skylake (XPS 13 9350) TSC is way off

From	John Stultz <john.stultz@linaro.org>
Newsgroups	linux.kernel
Subject	Re: Skylake (XPS 13 9350) TSC is way off
Date	2015-12-21 23:00 +0100
Message-ID	<qIgEP-3vy-45@gated-at.bofh.it> (permalink)
References	(2 earlier) <qBp0t-5qO-1@gated-at.bofh.it> <qBpa9-5uf-1@gated-at.bofh.it> <qBpjP-5xC-5@gated-at.bofh.it> <qBptw-5Bi-21@gated-at.bofh.it> <qI3Rg-40k-7@gated-at.bofh.it>
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On Mon, Dec 21, 2015 at 12:10 AM, Jon Masters <jonathan@jonmasters.org> wrote:
> On 12/2/15, 6:55 PM, John Stultz wrote:
>>
>> On Wed, Dec 2, 2015 at 3:42 PM, Andy Lutomirski <luto@kernel.org> wrote:
>
>
>>>> On a hunch, are you running chrony instead of ntpd?
>>>
>>>
>>> Yes, this is indeed chrony.
>>
>>
>> Ok. I'll have to look closer. The last time that message came up it
>> was in a report of a bug that chrony uncovered with the internal
>> correction being too slow. I know chrony is much more aggressive
>> compared to ntpd in tweaking the freq value for the initial converging
>> correction at startup, so maybe that along with something else is
>> causing us to get out of spec.
>
>
> Can you copy me on followup? I'm seeing similar behavior with chrony on
> recent kernels on a couple of different ARM server prototype systems.

A patch for this just landed in tip/timers/core and is pending for 4.5
http://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/commit/?id=ec02b076ceab63f99e5b3d80fd223d777266c236

thanks
-john
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Re: Skylake (XPS 13 9350) TSC is way off Jon Masters <jonathan@jonmasters.org> - 2015-12-21 09:20 +0100
  Re: Skylake (XPS 13 9350) TSC is way off John Stultz <john.stultz@linaro.org> - 2015-12-21 23:00 +0100

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