18,2 Gb RAM used after clean boot...who use that?


I have 32 GB RAM on my linux computer. After typing my password on session log in screen, I launched system monitoring and I discovered that 18,2 GB of RAM are used by Manjaro while no app has been launched. I have no app starting up on session start, so I was wondering how can I track it and see what can be saved.
According to system monitoring, the app which used the most RAM after my login is system monitoring with 104 Mb…
I know Linux tries to block the RAM to be able to use it, so we have the feeling that RAM is used, while it is only locked by the system. But why 18.2 GB over 32 GB and not locking the 32 GB in this case ?

‘top’ command does not show me anything suspicious.
‘free’ command just confirms that 18.2G are used and the rest is free so around 13Gb


Unused memory is wasted memory - the linux kernel will cache filesystem and /tmp is tmpfs which is ram.

zcache or zram will also use ram for storage and cache.

Your ram will be there when you need it - the more ram you have the more the system will use - after all you want a system as fast as it can possibly be - right?

My plasma system with a vivaldi open and 10 tabs - it doesn’t bother me

 $ free -h
               total        used        free      shared  buff/cache   available
Mem:            62Gi       6,1Gi        44Gi       108Mi        12Gi        56Gi
Swap:          8,8Gi          0B       8,8Gi

starting a windows vm

 $ free -h
               total        used        free      shared  buff/cache   available
Mem:            62Gi        22Gi        28Gi       111Mi        12Gi        39Gi
Swap:          8,8Gi          0B       8,8Gi
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Do you have a /swapfile ?
Nevermind, that was stupid of me.

My KDE system does not do what you’re saying yours is doing, so my question is what option have you selected for system restore? Could it be that your desktop is trying to restore where you left off when you logged out?

I’ve always found starting with an empty session works best for me.

Anyway this is what my memory looks like right now with various apps open: steam, vivaldi, thunderbird, konsole, system settings, ksysguard

free -h                                                                                                                 ✔ 
               total        used        free      shared  buff/cache   available
Mem:            31Gi       4.4Gi        21Gi       555Mi       6.5Gi        26Gi
Swap:           31Gi          0B        31Gi

Um, I don’t know where you got that, but that doesn’t make any sense at all. :face_with_raised_eyebrow:

As @linux-aarhus said, unused RAM is useless RAM. Therefore, the Linux kernel attempts to make optimal use of the available resources by caching and buffering, which allows for applications to open quicker and for their data to remain in memory as long as possible.

However, as soon as more RAM is needed, the kernel will release as much cache memory and flush as many buffers as necessary to accommodate whatever virtual memory the new process requires. And if necessary for the amount of virtual memory needed and you have a swap device, then the kernel will park some data on the swap device.

That’s all there is to it, really.

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With all respect, there is nothing in manjaro that can consume 18 GB RAM, so it is clearly some misconfiguration somewhere. Like zram setting, or tmpfs, or allocation for video card in bios…something like that.

What does free -h shows exactly?

Maybe try htop instead of top there you can sort the memory use

RAM isn’t like paper - it simply stores things temporarily. When I upgraded from 8 to 16GiB I noticed that shortly after boot, my RAM would be about 1/3 full after booting - but it’s not worth being worried unless you actually run out.

It’s like having a room filled with air and worrying there’s no space to get your friends in there…