zlacker

>>hugodu+(OP)
"Firecracker's RAM footprint starts low, but once a workload inside allocates RAM, Firecracker will never return it to the host system."

Firecracker has a balloon device you can inflate (ie: acquire as much memory inside the VM as possible) and then deflate... returning the memory to the host. You can do this while the VM is running.

https://github.com/firecracker-microvm/firecracker/blob/main...

>>rgbren+ig
The first footnote says If you squint hard enough, you'll find that Firecracker does support dynamic memory management with a technique called ballooning. However, in practice, it's not usable. To reclaim memory, you need to make sure that the guest OS isn't using it, which, for a general-purpose workload, is nearly impossible

>>paulv+Xk
Yeah it's pretty hard problem as you'd need to defragment physical memory (while fixing all the virtual-to-physical mappings) to make contiguous block to free