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

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From	Andy Lutomirski <luto@kernel.org>
Newsgroups	linux.kernel
Subject	Re: Skylake (XPS 13 9350) TSC is way off
Date	Thu, 03 Dec 2015 01:10:02 +0100
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On Wed, Dec 2, 2015 at 3:42 PM, John Stultz <john.stultz@linaro.org> wrote:
> On Wed, Dec 2, 2015 at 3:38 PM, John Stultz <john.stultz@linaro.org> wrote:
>> On Wed, Dec 2, 2015 at 3:25 PM, Andy Lutomirski <luto@kernel.org> wrote:
>>> In case it's at all useful, adjtimex -p says:
>>>
>>>          mode: 0
>>>        offset: 0
>>>     frequency: 135641
>>>      maxerror: 37498
>>>      esterror: 1532
>>>        status: 8192
>>> time_constant: 2
>>>     precision: 1
>>>     tolerance: 32768000
>>>          tick: 10000
>>>      raw time:  1449098317s 671243180us = 1449098317.671243180
>>>
>>> this suggests a rather small correction, so I really have no idea what
>>> "Adjusting tsc more than 11% (8039115 vs 7759462)" means.
>>>
>>> John, you wrote this code.  What does the error message mean?
>
> Also, is there a behavior issue you're seeing or is this just a
> concern about the warning? I assumed it was the first, but digging up
> the thread here I'm not sure I see any specific problems listed.

No, there's no actual problem I'm aware of other than the error
message.  Skylake's TSC is different from other chips, and this is
Skylake, and I was worried that something was wrong with the initial
calibration.  It seems like the initial calibration may be fine,
though.

--Andy
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Thread

Skylake (XPS 13 9350) TSC is way off Andy Lutomirski <luto@kernel.org> - 2015-12-02 21:10 +0100
  RE: Skylake (XPS 13 9350) TSC is way off "Brown, Len" <len.brown@intel.com> - 2015-12-03 00:00 +0100
    Re: Skylake (XPS 13 9350) TSC is way off Andy Lutomirski <luto@kernel.org> - 2015-12-03 00:30 +0100
      Re: Skylake (XPS 13 9350) TSC is way off John Stultz <john.stultz@linaro.org> - 2015-12-03 00:40 +0100
        Re: Skylake (XPS 13 9350) TSC is way off Andy Lutomirski <luto@kernel.org> - 2015-12-03 00:50 +0100
          Re: Skylake (XPS 13 9350) TSC is way off John Stultz <john.stultz@linaro.org> - 2015-12-03 01:00 +0100
        Re: Skylake (XPS 13 9350) TSC is way off John Stultz <john.stultz@linaro.org> - 2015-12-03 00:50 +0100
          Re: Skylake (XPS 13 9350) TSC is way off Andy Lutomirski <luto@kernel.org> - 2015-12-03 01:10 +0100
      RE: Skylake (XPS 13 9350) TSC is way off "Brown, Len" <len.brown@intel.com> - 2015-12-03 04:30 +0100

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