On Wed, May 16, 2018 at 08:13:37PM +0000, Matt Middendorf via Linuxptp-devel 
> I want to change the way the step threshold is used in pi.c. Currently the 
> servo gets unlocked and servo code is skipped.This will allow the clock to 
> step, which I don't want to happen. I changed the code to:
> Limit the master_offset to the range (+/-) of the threshold.Don't unlock the 
> servo.Process the limited master_offset with the servo.
> I have tested this code and it works great to remove jitter due to network 
> traffic.The value of the step threshold can easily be determined by 
> performing a baseline run. If modifying the existing could is frowned upon, a 
> new configuration parameter could be added called "max_offset" to perform the 
> same function.

Hm, that is an odd approach to deal with jitter. I suspect it would
work only with the PI servo and even in that case it doesn't make much
sense to me.

The servo itself is supposed to filter the noise in measurements. If
the jitter is large, the PI servo should be configured with smaller P
and I constants, like with SW timestamping for instance.

Have you tried that?

Miroslav Lichvar

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