[Thinlinc-technical] Using fair share scheduling on ThinLinc agent hosts

[Björn Fischer]

Dear subscribers,

at our site we are currently experimenting with fair share scheduling on
ThinLinc agent hosts. Our approach still has some issues, but generally
it looks quite promising so that we would like to share our experience
with all of you. Any feedback on this topic is highly appreciated.

At the Center for Biotechnology (CeBiTec) at Bielefeld University we
provide scientist's desktops (internet and office applications, and
scientific applications) for researchers and teachers.

Formerly based on SunRay technology (using Solaris' FSS), we now use a
ThinLinc-4.9 setup with 5 VSM agents (each 56 Cores, 376GB RAM). Our
approach uses Ubuntu-18.04 on the bare metal and each VSM agent is
running inside an LXD-3.0 container, also with an Ubuntu-18.04 user
space. This setup works exceedingly well wrt migration and deployment
of agent hosts.

Usually, about 30 users share a single VSM agent host which handles
the load quite well -- as long as there is no firefox, thunderbird, or
similar process going berserk. It may also occur that an interactive
science app suddenly generates lots of load. These situations lead
to lags for all users on the system deteriorating the general user
experience.

In order to fix that problem we are experimenting with the fair share
scheduling feature of the Linux kernel which is controlled by the
cgroups API. With fair share scheduling enabled, a user can acquire all
CPU resources he/she wants as long as there is idle time on the system.
When CPU time is exhausted the scheduler splits CPU time equally across
all demanding users. In other words the user cannot single-handedly slow
down the whole system any more.

The deployment we have at hand right now seems to work quite well apart
from some issues with systemd.

Is anyone doing something similar?

If anyone is interested in technical details of our setup, or may
provide help with our systemd problems, please let me know.

Björn
-- 
CeBiTec -- Bioinformatics Resource Facility