Jail resource limits?

[Miroslav Lachman]

Greg Lewis wrote on 11/07/2019 05:43:
> Hi all,
> 
> I've been playing with limiting FreeBSD jail resources with both cpuset and
> rctl and I wondered if anyone knew of a way to tell from inside the jail
> what these limits are?
> 
> E.g. let's say I use cpuset to limit a jail to CPU0 and rctl to limit a jail
> to only using up to 4G of memory.  Can I then tell from a process running
> inside the jail that these limits are in place?  I tried dumping out
> sysctl -a and couldn't see anything that seemed to match up with the limits
> I put in place.  I haven't yet tried writing some code to call cpuset(2)
> to see if that works.
> 
> The reason I'm asking is that some software may make decisions based on the
> resources available and I'd like to have a way to accurately determine
> those resource limits for jailed processes.

cpuset called inside a jail will return available cores

# cpuset -g
pid -1 mask: 2, 3

I don't think it is possible to query rctl limits.

Maybe somebody else knows better.

Miroslav Lachman