[time-nuts] PTPv2 grandmaster with a Z3805A?

Mike S mikes at flatsurface.com
Tue Aug 20 12:16:00 EDT 2013


On 8/20/2013 11:40 AM, Wojciech Owczarek wrote:
> I would recommend the TSC time source: lowest read overhead.
>
> All three have different behaviours - different (cold start) frequency
> offset and different drift rates once stabilised and then left drifting.

By default, the tsc is calibrated at each boot, which means that timing 
will likely change (and ntp drift values will be off) each time you boot.

There's a linux kernel command line option which will fix that and 
provide consistency between boots, something like  "clocksource=tsc 
tsc_khz=2410988". The exact value depends on how fast the processor is 
clocked.


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