Re: [LAU] What exactly is JACK DSP % usage ?

On Tue, February 23, 2016 8:32 am, Jonathan Brickman wrote: I don't think that follows. That seems to me that you are asking if since you have a lot of processing going on, would adding additional overhead help. If you have multiple processing chains that do not depend on one another, then using jack2 may help, it can take advantage of multiple processor cores. I don't know if that would help with the two yoshimi instances or not, but since you do not appear to be CPU limited, then probably not. Real time operation is often more about overhead, the minimum amount of time it takes for the OS to switch between user mode and kernel mode, the time it takes the scheduler to determine the next process to run, the amount of time it takes the kernel to read the current state of the interrupt controller and call interrupt handlers, things like that. A lot of those things take fixed amounts of time, so the best thing you can do for a given system is to try to do them less often, i.e. larger buffers. For given hardware you may be able to change the system behavior by modifying firmware settings, like turning off hyperthreading/SMT, or changing power saving features. Probably those are documented in some wiki somewhere, but I can't find it on the jackaudio.org wiki at the moment. Of course you have to start by making sure that the OS runs the real-time tasks first, and does not perform general OS housekeeping tasks when there is real-time work to be done. That is the point of the -RT kernel patches and to a lesser extent the low-latency config option in the unpatched kernel tree. -- Chris Caudle