[Jack-Devel] ardour3, netjack, bandwidth, xruns

Hi,

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

Goal is to use windows orchestral VSTi(s) whose required 'dongle' is on 
a windows machine.

   ardour3:midi-track-1 => slave:midi-input-1
   slave:audio-out-1    => ardour3:audio-track-in-1
   slave:audio-out-2    => ardour3:audio-track-in-2

Pretty simple, actually, but I'd like 48 channels of audio to come back 
from the slave.

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.

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

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