Early swap usage

Hello.

I'm using Kubuntu 19.10 and noticed that swap was used very early after starting the desktop, even if there's still RAM available (4Gb RAM, KDE Plasma Desktop). How can I troubleshoot what's causing this early use of swap ? isn't swap supposed to be used only if RAM is full ? can I do something about it ?

What does top or htop tell you about memory usage?

Please see imgur album here : https://imgur.com/a/ba7FR6j

Originally Posted by ychaouche isn't swap supposed to be used only if RAM is full ? can I do something about it ?

No and no.
Swap is a resource available to the memory management system to manage and balance as it sees fit. Many man years of effort by a bunch of very smart people have gone into the code.
Go find a real problem to worry about. If it really worries you, issue a swapoff/swapon.

Ah, this is good to know. The real problem that worries me is the system being slow after some time. I have linked this with swap usage because many times when system becomes unresponsive, I see one or two processes in "disk sleep" state, which means they are waiting for data from disk (could writes also be blocking ? dunno), which is why I thought maybe they are reading from the swap file (since the monitoring tools show swap usage). But after reading your post I assume swap is not an indicator of poor system health.

www.linuxatemyram.com will explain some details.

cat /proc/sys/vm/swappiness
60

You can change that.
https://wiki.archlinux.org/index.php/Swap#Swappiness

Look at your distros docs.