On Tue, Apr 9, 2019 at 5:52 AM Dario Lesca d.lesca@solinos.it wrote:
On a i7+16Gb+SSD notebook of a my friend I have install Fedora 29 workstation (all work fine! ... thank to all!) and into qemu/kvm/libvirtd via virt-manager I have install a win10pro with all virtio driver (disk, network, ecc..).
After few days my friend say me that the win10 is slow and less efficient than same installation on another PC with VirtualBox. He told me "virtualbox is better and faster"
What backing storage is the VM using? qcow2, raw, LVM? If it's a file, what filesystem is it on?
It's worth experimenting with the virtio disk "cache mode" setting, in virt-manager under advanced > performance options. I use unsafe, which is bad advice to give because it really is not safe if there's a crash, good chance the guest filesystem is toast. But it's a lot faster. And I consider my VM's throwaway. There may be another cache setting that's not so dangerous but also doesn't penalize like the default. I think what you want is cache=writeback if it's a file, and cache=none if it's LVM. I would say test both and pick the one with better performance.
https://doc.opensuse.org/documentation/leap/virtualization/html/book.virt/ch...
Note that some of the cache modes must be paired with a specific IO mode, e.g. unsafe only works with threads.