Add support for free-page-reporting
The virtio-balloon device now has the ability to report free pages back to the hypervisor for reuse by other programs. This kernel feature allows for more stable and resource friendly systems.
The feature was added to upstream linux kernel v5.7
(from https://lwn.net/Articles/808807/)
This series provides an asynchronous means of reporting free guest pages to a hypervisor so that the memory associated with those pages can be dropped and reused by other processes and/or guests on the host. Using this it is possible to avoid unnecessary I/O to disk and greatly improve performance in the case of memory overcommit on the host.
This feature is available in QEMU and is enabled with free-page-reporting=on
default virt setting should be off but the user should be able to enable it.