NAME
viomb
- VirtIO memory ballooning driver
SYNOPSIS
virtio* at pci? dev ? function ?
viomb* at virtio?
DESCRIPTION
virtio(4)
defines an interface for efficient, standard, and extensible I/O between
the hypervisor and the virtual machine.
The
viomb
driver supports the virtio-compliant memory ballooning device.
Memory ballooning works as follows:
-
The host operator requests a guest to return some amount of memory to the host
(via e.g. Qemu monitor balloon command).
-
The hypervisor sends the request via VirtIO memory ballooning device.
-
The guest
viomb
driver requests allocation of that amount of physical memory from the
NetBSD
memory management system.
-
The
viomb
device tells the hypervisor the guest physical memory address of the
allocated memory via VirtIO memory ballooning device.
The sysctl node
hw.viomb.npages
shows the requested number of memory pages to return to the hypervisor, while
hw.viomb.actual
shows the actual number of memory pages that are already returned to the hypervisor.
SEE ALSO
virtio(4),
sysctl(8)
HISTORY
The
viomb
device driver appeared in
NetBSD6.0.
BUGS
The userland interface should be same as the Xen ballooning device.