[etherlab-users] Syncing master to the reference slave: should I care?

[Mohsen Alizadeh Noghani]

Hello everyone.
In terms of choosing the reference clock in the network, there are two
options. In the first method, PC clock is chosen as the reference and
in the second one, slave 0's clock is the reference.
1- Syncing slave 0's clock to the master (application) time: this is
the method used by default by the EtherLab master.
2- Syncing master (application) time to slave 0: requires implementing
the synchronization algorithm by the user, as seen in "rtai_rtdm_dc"
example. This method boasts lower drift, as the slave's clock is more
stable.

However, in my experience, the latter method is more prone to master's
jitter, and thus less reliable during a long-term run (e.g. a 24h test
under stress).
My area of application is robot motion control.
The question is, using the first method, should I care about clock
drift? I feel that, even if all the clocks are drifting, as long as
they are synchronized with respect to each other, there shouldn't be
any issues.
Best,
Mohsen