bbb-webrtc-sfu (and mediasoup) are running in the CFS scheduler which
means it has to compete with (much) lower priority tasks like
presentation conversion, recording processing, [...]
Since it encompasses an RTC application which also handles audio, it
should be _at least_ on the same scheduling policy as FS/bbb-html5 - and
that should be safer now with mediasoup which has a lower footprint
(and generates lower CPU noise overall).
This commit puts bbb-webrtc-sfu in the FIFO scheduling policy (same as
bbb-html5). Also bumps bbb-html5 nice level up to 18 and sets SFU to
nice 19 (so bbb-html5 has some advantage when push comes to shove).
This can be improved further by using per-process priorities in SFU.
Ideally we'd want mediasoup audio workers and mcs-core to be the same
priority as FS (so higher than bbb-html5), but the rest of them
(video/screen workers) to be the same or lower than bbb-html5. For
future reference:
- https://github.com/bigbluebutton/bbb-webrtc-sfu/commit/3e245122dfa155ecb77b536eeadac1e4607cee
- 66d443d204
* fix unit name: the unit name on Ubuntu is `redis-server.service`
* services which need a working redis require both After= and Wants=
See the description in the `systemd.unit` man page.
