Hi all! I've been away for a while. Because I'm currently awaiting the delivery of an Organelle, I wanted to get my brain back into the Pd world.
Since about 2015 or so, my main performance instrument has been a Raspberry Pi 2b running this kernel: https://blog.emlid.com/raspberry-pi-real-time-kernel/
I'm interested in writing about my experiences here because in researching and preparing to use the Organelle, I ran into some newer Pi OS options that claim to have good realtime perf, etc. -- specifically Patchbox OS.
However, upon running it on my 2b, I immediately noticed that it was overall quite sluggish (just logging in and using the terminal via SSH was painful) and besides which, the audio produced was unusably distorted with my USB audio device (an ancient MAudio MobilePre) no matter what I set Jack/ALSA to use.
Contrast that with Wheezy running the PREEMPT kernel. I run quite heavy patches on multiple cores responding to accelerometer and gyrometer data coming in via a USB Wifi AP using a buffer size of 128 samples, 3 frames, at 44.1kHz seemingly effortlessly with no clicks or dropouts. Granular synths, FM synths, vocal processing with long delay lines, a few Freeverb instances.
Has anybody else used or compiled the kernel for more recent OS versions/Pi models and had similar luck? I'm interested in being able to compile kernels myself so I can see if the benefits carry over to newer Pi models and/or the Organelle (if necessary).
Maybe I'm just hamstrung from the start by using such an antiquated USB device with an antiquated Pi model, since the latencies are far better in any case when using a Hat-type interface, and I shouldn't worry about it so much.