[Ardour-Users] ardour3, netjack, bandwidth, xruns

[David Santamauro]

Happy new year ... if this isn't the appropriate list, direct to the 
right one, thanks.

I've started creating my orchestral template using ardour3 (on the 
master) and a slave. When I reach a certain number of tracks the xruns 
start piling up.

Master message(s):
Wed Jan  1 07:15:08 2014: NetMaster : overloaded, skipping receive from 
'nslave01'

... does this mean the master is overloaded?

The specs:
   - master is an 8-core/16GB RAM
   - slave is 4-core/16GB RAM

Both have Gb network interfaces and both are connected to a Gb switch.

ardour3 does take CPU slices but the master load avg is ~ 85% idle and 
DSP load < 20%.

Viewing network traffic using iptraf, I see total usage in the 45Mb/s 
(4% utilization) range for both master and slave -- clearly room to 
spare so I'm assuming there is some other bottleneck somewhere.

There are no xruns on the slave.

I guess the questions are:

   - are there hard limits on the number of tracks that can be used when 
using using jack over the network?

   - Is there a formula to figure out this out, e.g., is there a 
relationship between the size of the jack graph and data per cycle?

   - Are there settings (network or for jack_load netmanager) that would 
help this situation?

Both master and slave jackd versions are the same:

$ jackd -V
jackdmp 1.9.9.5

I've read this [1] and it appears there are two modes: sync and async. 
I'll try toggling this and see what happens.

... but any other help would be appreciated.

David

[1] http://trac.jackaudio.org/wiki/WalkThrough/User/NetJack2