What causes systemctl set-property very often?

Ask Fedora
1

I snapshot my /etc every day. One thing I notice is there are frequent changes, almost every week on an average but sometimes more or less frequently, in files like the following, for all the users. This system was Fedora 41, and upgraded to Fedora 42 around November 20. But these changes keep happening in both Fedora 41 and 42.

systemd/system.control/user\<user id\>-.slice.d/

  1. 50-IOWeight.conf : CPUWeight oscillates between 500 and 100.
  2. 50-MemoryMin.conf : MemoryMin oscillates between 0 and 262144000
  3. 50-IOWeight.conf : IOWeight oscillates between 500 and 100

etc. I don’t change these files, and I don’t explicitly call systemctl set-property. I don’t make any changes that I suspect of causing these changes. I do use the system, so something is implicitly doing this.

My Fedora usage summary : I use Gnome, a few virtual machines in virt-manager, install new software using dnf. The “Power Mode” in Gnome status bar is always “Performance”, so this should not be caused by it. I am not sure if any of this is related to system.control, I am just trying to give hints to informed people here who can educate me about this. I use pretty standard software , a huge majority from Fedora repositories.

If there is no famous process that does this, how should I investigate ? I can setup an inotify trigger for this, but it will still not tell me who is doing it.

2

I wonder if there is a tool running that is “tuning” your system for you?

3

Yes, “tuning” is the right word for something that might try this. Do you have any examples ?

Generally I don’t like software that is “intelligent”, or “thinks” on its own - but I might have installed something like that in ignorance.

I need an alarm to tell me whenever any process tries to edit these files - but I can’t think of anything that can do it.

4

You may be able to use the inotifywait tool to see what is going on.
I’ve not tried using the tool. found it via web search, but it looks close to what you need.

Let’s us know how you get on tracking this issue down.

5

If you can’t figure this out otherwise, here’s a heavyweight solution. Install the systemtap package. Run sudo stap-prep. Put this in a file named, say, etc.stp, replacing user id with the correct value:

probe vfs.write
{
  if (pathname == "/etc/systemd/system.control/user-\<user id\>.slice.d/50-CPUWeight.conf")
    printf("50-CPUWeight.conf written by %s (pid %d, uid %d)\n", execname(), pid(), uid())
}

Run sudo stap etc.stp. Come back later and see if it has printed anything. Press Ctrl-C to exit from stap when you are done.

1 Like
6

Wow! Thanks a lot. This seems extremely powerful.

7

That file should be generated by uresourced as stated in the comment inside the file.