illumos gate

On hosts which are primarily intended to run bhyve VMs, it would be advantageous to set aside memory in a reservoir specifically meant for bhyve guest memory allocations. This would allow bhyve to quickly and confidently allocate memory for instances without any chance of the ARC (or other large consumers) to soak up free pages, forcing potentially lengthy reaping activity. Use of such a reservoir could be explicitly opt-in, where memory was added to the reservoir via a CLI utility, and bhyve instances were configured to allocate from it when starting. Alternatively, on systems which did not wish to dedicate memory to bhyve instances (particularly when they were not running), bhyve could make "transient" allocations which function similar to things today (where memory is scrounged from the freelist, and reaping from the ARC and kmem).