Ardupilot loop timings improvement

[Williangalvani]

Add to ArdupilotManager.py ardupilot launch cmdline: --cpu-affinity 3

Add to /boot/cmdline : isolcpus=3 nohz_full=3

ideas from here: https://www.suse.com/c/cpu-isolation-practical-example-part-5/

Moving the interrupts didn't seem to help.

This makes the last CPU exclusive for ardupilot. Preliminar tests looked decent, though not ground-breaking:

Before:

After:

For this to be implemented we need:

• [ ] Ardusub 4.1.1
• [ ] A way of changing command line depending on the firmware in ArdupilotManager.py
• [ ] A way of changing cmdline.txt

[patrickelectric]

@Williangalvani is this still a thing ?