Re: [Linuxptp-users] Expected throughput of the ptp4l

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

On Tue, Mar 17, 2015 at 05:28:45PM +0000, Chandra Mallela wrote:
> As for 'what is that supposed to achieve?', in ideal scenario, targeting 50pbb for CDMA is what I look at. I am further trying to analyze SyncE requirements from 1588 perspective, which seems too tough at this moment due to OS scheduling jitter itself.
> 
> Please correct me as appropriate and pour in your thoughts.

So 50 pbb means 50 nanoseconds.  That should be attainable with a more
moderate Sync rate, but it depends on your hardware time stamping
resolution, etc.

With SyncE, you need to hack ptp4l *not* to touch the frequency
adjustment.  I have some patches in the works for this, but you can
change the code yourself in the mean time.

Using SyncE and the default 1 Hz Sync, I have seen two nodes
synchronized to within 8 nanoseconds (the clock period of those
systems).

So, I really, truly don't see the need for 512 Syncs per second.  But
if you want run that rate, then you are going to have to optimize your
system, especially WRT to real time response, as I said before.

Thanks,
Richard