After watching Andrew Johnston amazing video tutorial (Thanks!), I realised I wasn´t using JACK correctly. There were lots of settings I wasn´t setting up correctly, but two stood up. First one was the Real time one. I can´t get that one to work on my machine. If I attempt to start JACK in real time, it fails, not sure why… I am using my integrated soundcard (unfortunately, until I upgrade my equipment), but I am not sure if that is the problem. Any ideas how to make that work?
The second one was setting JACKDMP up. I downloaded jackdmp and installed it, but when done, JACK would not work. I ended up having to uninstall it. Having said so, even if I use JACK through jackd, it seems to as if both CPUs were in use. I never see too big a difference between them. In other words, it never looks as if one is at 5% and the other one is at 95%. Is there a way to find out if both CPUs are in use aside from the system monitor?
RT setup does not require recompiling your kernel. It has to do with user’s privileges to run processes with the SCHED_FIFO scheduler bit. Normally, only root can do that but nowadays, the PAM security module allows others to do so. All you have to do is described in the discussion I mentioned above.
The kernel recompiling is for something called “complete preemption” which turns the kernel into near ideal real time system. The normal kernel is doing a good job nowadays (2.6.28 is quite good), even without the full complete preemption patch.
Jackmp (aka Jack2) makes no difference to CPU utilization for the most common audio configurations. Why? Because the most common ones involve serial audio data handling (e.g. from a software synthesis engine to a disk recorder) and the different JACK clients cannot be run in parallel.