I am using qubes-os 4.2 on a bit dated laptop with an i5 cpu and only 8 GiB of RAM.
Because of the low RAM, I have chosen at installation to use sys-net also as sys-usb.
Now I noticed that nearly all my qubes are configured to be included in memory balancing except for sys-net. It has an initial and maximum of 425 MiB. This turns out to be regularly too low for smooth operation.
Now my question is: is there a (security) reason why it is defaulted like this? Is it a bad idea to put sys-net in memory balancing and/or give it more space?
If you were using sys-net just for networking then 425 MiB should be more than enough, but since you’re using it instead of having a sys-usb qube, I’d recommend increasing the memory to at least 800 MiB.
If you left swappiness at the default (60), it’s to be expected. The Linux kernel’s memory management is programmed in such a way that even with lots of extra memory you’ll expect some swap to be used if swappiness is not set to 10 or even 1.
“Free” does not include buffers/caches. After enough time on a Linux system that performs I/O, the “free” ram will always tend towards 0, as the unused memory gets used by caches and buffers, and that’s fully intended functionality that makes the OS faster. What you should probably be looking at is the “Available” value, as reported by free -h.