Need help with Core Isolation, Bridging, etc

General Discussion
1

Hi all,

I’m building a server to exclusively run Roon Server and am looking at doing the following:

a) Set a static CPU frequency (lower than what the CPU normally runs at). CPU is an Intel Xeon Gold 6138.

b) Setting up CPU Core Isolation / Affinity to have certain processes run on certain cores.

c) Bridge 2 ethernet ports on the server.

I would be grateful if someone could point me in the right direction to get this done.

Thanks,

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2

Hello and welcome to the forum.
To set a static CPU frequency you can change the CPU Governor in dietpi-config -> Performance Options -> CPU Governor to userspace and set a fixed frequency.

To setting up CPU affinity you can use the command taskset.
E.g. to run nvim only on core 0 and 1 you do:

taskset -c 0,1 nvim

This setting will not survive a reboot, so you would need to setup a startup script or a systemd service or something similiar, to apply this at boot.

For bridging ethernet ports you would need to edit /etc/network/interfaces. In this example we bridge eth0 and eth1 to br0:

iface eth0 inet manual
iface eth0 inet6 manual
iface eth1 inet manual
iface eth1 inet6 manual

auto br0
iface br0 inet static
    address 192.168.178.42
    netmask 255.255.255.0
    bridge_ports eth0 eth1

Then restart the network with sudo ifdown -a && sudo ifup -a.

Instead of using a static address you can of course also use DHCP. Tweak the values to your likings.

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3

This is brilliant. Thank you for your quick and detailed reply. I will try this tonight.

I’m a bit of a newbie so sorry for being a pain but could you please let me know how to do this:

“This setting will not survive a reboot, so you would need to setup a startup script or a systemd service or something similiar, to apply this at boot.”

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4

You can run dietpi-autostart and select the option 14: Custom script (background ...) and then edit the file /var/lib/dietpi/dietpi-autostart/custom.sh.

Add the following lines (in this example we set nvim to run just on core 0:

/usr/bin/taskset -c 0 nvim

Save the file and from now on at each reboot it will be executed.

5

Great, so if I had multiple cores to set, I would just add multiple lines?

/usr/bin/taskset -c 0 nvim
/usr/bin/taskset -c 1 abcd
/usr/bin/taskset -c 2 xyze

6

Exactly.

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7

Hi,
Installed Dietpi and managed to get the bridge working but had to run the following as well:

apt install bridge-utils
reboot
brctl addbr br0
brctl setfd br0 0
brctl addif br0 eth0 eth1

I’m now facing another issue. I have a USB drive plugged in to the PC and have mounted it. However, I am unable to access it from within Roon. It says ‘unauthorised’. I cant figure out how to set permissions to allow all users access.

Thank you.

8

What filesystem does the USB drive use?
Recommended way to access your music is to copy it into /mnt/dietpi_userdata/Music.
https://dietpi.com/docs/software/media/#__tabbed_17_3

Otherwise you need to adjust the permissions manually, like:

chmod 0755 /path/to/music
chown -R roonserver:root /path/to/music

Can you share also the logs:

journalctl -u roonserver
cat /var/log/roonserver
9

Thank you. That worked.
Is there a way to find and delete / disable unused processes?
I want only the minimum processes running.
Thanks

10

DietPi is already running a minimum of process by default. Usually processes added by user actions, configuration or software installations.

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