[systemd-devel] [HEADSUP] cgroup changes

Lennart Poettering lennart at poettering.net
Fri Jun 21 13:10:08 PDT 2013

On Fri, 21.06.13 12:59, Kok, Auke-jan H (auke-jan.h.kok at intel.com) wrote:

> > http://lists.freedesktop.org/archives/systemd-devel/2013-June/011388.html
> >
> > Here's an update and a bit on the bigger picture:
> Thanks for doing this - I am really looking forward to seeing this all
> take shape, and I hope to be able to leverage this in the future :^)
> All the points below are great, and problems that I've encountered in
> the past have all hinted towards this being the right way forward.
> #2 below has my interest - when you have some ideas about how the API
> will look I'd like to review it and match against our use cases...

Point #2 is precisely about not having APIs for this... ;-)

So, in the future, when you have some service, and that service wants to
alter some cgroup resource limits for itself (let's say: set its own cpu
shares value to 1500), this is what should happen: the service should
use a call like sd_pid_get_unit() to get its own unit name, and then use
dbus to invoke SetCPUShares(1500) for that service. systemd will then do
the rest. (*)


(*) to make this even simpler we have been thinking of defining a new
"virtual" bus object path /org/freedesktop/systemd1/self/ or so which
will always points to the callers own unit. This would be similar to
/proc/self/ which also points to its own PID dir for each
process... With that in place you could then set any resource setting
you want with a single bus method call.

Lennart Poettering - Red Hat, Inc.

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