Investigate how to manage builds using VMs

We most likely want to run our builds inside of VMs. However, a lot of builds will require vasts amounts of memory. If we give a lot of memory to all our VMs, we won't have enough memory for many builds at all. As such, we should investigate how to share VM memory or whether we can use KSM. Another pursuit is a shared memory device.

See also: https://www.qemu.org/docs/master/system/devices/ivshmem.html and https://www.reddit.com/r/linuxquestions/comments/u3fs09/what_is_enable_shared_memory_option_in/jpbs8il/

changed the description

changed milestone to %0 - Proof of Concept

added needmust scopefeature labels

added buildbtwpoc label

assigned to @svenstaro

added statusin-progress label

For the record. It may be worth enabling free-page-reporting, which I just did for our existing custom gitlab runner (infrastructure@87a54893).

Thanks for mentioning this! This is already part of my experiments :)

For the record, here's the tool Sven is building for creating VMs and running things inside them. It will be called inside a small custom runner executor.