Re: [Linuxptp-users] issues with mixed software timestamp / hardware timestamp setup

[Richard C. <ric...@gm...>]

On Fri, Feb 08, 2019 at 08:22:31PM +0100, Frank Dekervel wrote:
> What i observe is:
> 
>    - the computers with hardware timestamps do sync fine
>    - the embedded system claims to be in sync with the other computers (eg
>    when i do pmc -u -b 0 'GET TIME_STATUS_NP'  the master_offset is less
>    than 100usec on the embedded system and on the other computers too)
>    - however, the clocks are totally not in sync (more than a minute apart
>    as reported by "date")

Be careful here.  The `date` command compares the systems clocks, but
the ubuntu system clock is not necessarily synchronized with the HW
clock in the MAC. 

>    - phc2sys is running on the ubuntu trusty computers but not on the
>    embedded system.

But with what arguments?  Which PTP clock is the master in your setup?

> My question is: what could be the cause of a low master_offset but still no
> clocks in sync ?

I guess that the ubuntu system time is simply independent of the
ubuntu PHC time.

> Also, we have setup monitoring to send alerts when time is not in sync,
> based on the output of "GET TIME_STATUS_NP". is this the right output to
> monitor ?

Yes, or you can monitor CURRENT_DATA_SET.offsetFromMaster

HTH,
Richard