[libvirt] [RFC] memory settings interface for containers

Dmitry Guryanov dguryanov at virtuozzo.com
Fri Nov 13 10:55:15 UTC 2015

On Thu, 2015-11-12 at 11:11 +0300, Nikolay Shirokovskiy wrote:
> Hi, everyone.
> I plan to add means to configure vz containers memory setting and have trouble
> getting it done thru libvirt interface. Looks like current interface fits good
> for vm memory managment but its not clear how to use it with containers. First
> let's take aside memory hotplugging which is obviously not suitable for
> containers. Then memory interface is represented by 2 parameters: total_memory
> and cur_balloon. For VMs total_memory can't be changed at runtime, cur_ballon
> can't be greater than total_memory. But for containers memory model is
> different. We have only one parameter and it can be changed for running 
> domains.

Not only one parameter, there are a lot of parameters, that can be tuned with
memory cgroup. But at least physical pages limit (memory.limit_in_bytes) and
swap pages (memory.memsw.limit_in_bytes) have sense.
>  So question is how to map this model to existing interface (it is
> unlikely to have a new interface for this case). I plan to make both
> parameters
> to have same meaning and be equal for containers and update virsh, API and xml
> model documentation accordingly.
> I'd be happy to hear core developers opinions on this topic.
Dmitry Guryanov

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