[libvirt PATCH 15/17] qemu: Add external_limit_manager config knob

[Daniel P. Berrangé]

On Mon, Mar 08, 2021 at 01:56:15PM +0100, Andrea Bolognani wrote:
> On Mon, 2021-03-08 at 10:52 +0000, Daniel P. Berrangé wrote:
> > On Fri, Mar 05, 2021 at 08:14:02PM +0100, Andrea Bolognani wrote:
> > > +# If enabled, libvirt will not attempt to change process limits (as
> > > +# configured with the max_processes, max_files and max_core settings
> > > +# below) itself but will instead expect an external entity to perform
> > > +# this task.
> > 
> > Can't users simply not set max_core, max_files, etc already ?
> 
> That works for things that are static and have a corresponding
> configuration option in qemu.conf, but the memory locking limit is
> dynamic, per-VM and needs to change as devices are added and removed
> from the guest.
> 
> > I think it is preferrable to have flags tailored specifically to
> > the individual limits, not a global flag. Otherwise you can end
> > up in a case where you want to disable the memory limits, but
> > keep the other limits set which is impossible with this global
> > flag.
> 
> Since what I'm interested in is the memory locking limit, I guess I
> could turn this into
> 
>   max_memlock_external = 1
> 
> or even
> 
>   max_memlock = "external"
> 
> with "dynamic" being the other accepted value, which would be the
> default and would behave as libvirt does today.
> 
> Do you think that would work better?

I think that would be better, as it has clearly defined scope which we
can maintain more accurately long term.


Regards,
Daniel
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