Re: Regression: can't apply frequency offsets above 1000ppm.
From: Nuno GonÃalves
Date: Thu Sep 03 2015 - 06:10:44 EST
The default chrony config from the debian package can't bring the
clock in sync because it doesn't do steps, and it starts 15 years in
the past. You had some other external help.
Assuming "all factory config" just make sure to disable timesyncd:
sudo systemctl disable systemd-timesyncd
And then reboot in a clean chrony state:
sudo systemctl stop chrony && sudo rm /var/lib/chrony/chrony.drift &&
You can also just cycle power to get back to year 2000, since the
beaglebone doesn't have a battery backed RTC.
After boot you can see this frequency estimates are allways very large
(usually from +-10.000...80.000):
debian@bbb1:~$ chronyc sourcestats
210 Number of sources = 4
Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev
ftp.claranet.pt 5 3 8 -40146.551 130300 -2720ms 61ms
a88-157-128-22.cpe.netcab 5 3 8 -35628.008 129339 -2393ms 68ms
a212-113-190-2.cpe.netcab 5 3 8 -45213.773 169140 -3057ms 63ms
mirrors.dominios.pt 5 3 8 -39615.191 99995.367 -2694ms 53ms
To have it perform normally try for example 3.16.3:
sudo apt-get install linux-image-3.16.3-bone6
On Thu, Sep 3, 2015 at 12:16 AM, John Stultz <john.stultz@xxxxxxxxxx> wrote:
> On Tue, Sep 1, 2015 at 6:14 PM, Nuno GonÃalves <nunojpg@xxxxxxxxx> wrote:
>> On Wed, Sep 2, 2015 at 2:03 AM, John Stultz <john.stultz@xxxxxxxxxx> wrote:
>>> On Tue, Sep 1, 2015 at 5:36 PM, Nuno GonÃalves <nunojpg@xxxxxxxxx> wrote:
>>>> On Tue, Sep 1, 2015 at 9:25 PM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
>>>>> On Tue, 1 Sep 2015, Nuno GonÃalves wrote:
>>>>>> There is a regression on the clock system since v3.16-rc5-111-g4396e05
>>>>>>  http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=4396e058c52e167729729cf64ea3dfa229637086
>>>>> That commit has absolutely nothing to do with NTP. I fear your bisect
>>>>> went down the wrong road somewhere.
>>>> You are right. It is v3.16-rc5-114-gdc49159:
>>>> I've triple checked it this time. Not sure where I did the mistake to
>>>> get it wrong by 3 commits.
>>> This commit is much more believable (though surprising as that change
>>> was found to greatly improve results for most uses).
>>> Can you provide any more details about how the problem is reproduced
>>> (kernel config, what userland images are you using, etc)? I've got a
>>> BBB myself so I can try to see whats going on.
>> I'm using a clean Debian image:
>> And just installing chrony from the feeds. With any kernel from 3.17
>> you'll have wrong estimates at chronyc sourcestats.
> Wrong estimates? Could you be more specific about what the failure
> you're seeing is here? The
> I installed the image above, which comes with a 4.1.6 kernel, and
> chrony seems to have gotten my BBB into ~1ms sync w/ servers over the
> internet fairly quickly (at least according to chronyc tracking).
> root@beaglebone:~# chronyc tracking
> Reference ID : 22.214.171.124 (time01.muskegonisd.org)
> Stratum : 3
> Ref time (UTC) : Wed Sep 2 23:07:05 2015
> System time : 0.001320852 seconds fast of NTP time
> Last offset : +0.001209910 seconds
> RMS offset : 0.002978454 seconds
> Frequency : 44.684 ppm fast
> Residual freq : +0.068 ppm
> Skew : 1.223 ppm
> Root delay : 0.073661 seconds
> Root dispersion : 0.021902 seconds
> Update interval : 518.3 seconds
> Leap status : Normal
> root@beaglebone:~# chronyc sourcestats
> 210 Number of sources = 4
> Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev
> 126.96.36.199 4 3 17m +1.593 30.515 +798us 802us
> unlawful.id.au 6 5 21m +1.080 2.312 +2731us 273us
> time.theplante.net 11 5 77m -0.536 0.915 -1165us 1044us
> time01.muskegonisd.org 4 3 25m +1.677 15.256 -342us 516us
> Can you send me your kernel config?
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