Re: [systemd-devel] Parent slices and resource control

[Patrick Dimond]

On Mon, Jun 01, 2020 at 12:22:03PM +0200, Lennart Poettering wrote:
> Consider this tree:
> 
> -.slice
> `- foo.slice
> |  `- miau.service
> `- bar.slice
> |  `- bar-quux.slice
> |  |  `- daemon.service
> |  |  `- otherdaemon.service
> |  `- bar-uuu.slice
> | ` rumpel.service
> `- zzz.slice
>`- zzz-yyy.slice
>   `- wuff.service
> 
> And now you turn on memory accounting in daemon.service. This would
> then propagate up the three, so you get memory accounting on all its
> parents too: bar-quux.slice, bar.slice and -.slice. And you will get
> it turned on forthe units immediately in throse, i.e. also in
> otherdaemon.service, bar-uuu.slice, foo.slice, zzz.slice. However, it
> will not be turned on in: miau.service, rumpel.service, zzz-yyy.slice
> and wuff.service, since those are neither in the path to the root
> slice nor immediately inside any of those slices.
> 
> Makes sense?
> 
> Lennart
> 
> --
> Lennart Poettering, Berlin

Yes! The diagram really helped. 

I think including a diagram like that would be helpful for others too.
I'm not sure where it should live or what the process is, but I'd be 
happy to put in the work to make that happen.

Thanks,
Pat
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[systemd-devel] Parent slices and resource control

[Patrick Dimond]

Hi,
I was reading the documentation for systemd.resource-control and came
across this sentence under accounting settings.

"Note that turning on memory accounting for one unit will also 
implicitly turn it on for all units contained in the same slice 
and for all its parent slices and the units contained therein."

What exactly is a parent slice? 

>From systemd.slice
"Slices are organized hierarchically in a tree. The name of the slice
encodes the location in the tree. The name consists of a dash-separated
series of names, which describes the path to the slice from the root
slice. The root slice is named -.slice. Example: foo-bar.slice is a
slice that is located within foo.slice, which in turn is located in the
root slice -.slice."

Does turning on accounting in one slice or service end up turning it on
for everything? Does every slice exist under the root slice?

Thanks for helping me improve my understanding,
Pat
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