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

From	Andy Lutomirski <luto@kernel.org>
Newsgroups	linux.kernel
Subject	Re: Skylake (XPS 13 9350) TSC is way off
Date	2015-12-03 01:10 +0100
Message-ID	<qBpDc-5UD-29@gated-at.bofh.it> (permalink)
References	<qBlSX-3wb-37@gated-at.bofh.it> <qBoxu-50H-55@gated-at.bofh.it> <qBp0t-5qO-1@gated-at.bofh.it> <qBpa9-5uf-1@gated-at.bofh.it> <qBpjQ-5xC-17@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

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

csiph-web