On Thu, Dec 02, 2021 at 06:01:03PM +0100, Tim Wiederhake wrote: > This was introduced recently in QEMU, see > https://bugzilla.redhat.com/show_bug.cgi?id=1982165: > > Bus locks disrupts overall performance since it blocks all other cores > (which must wait for the bus lock to be released before their memory > operations). > > For VMM, it can detect every bus lock acquired by guest VMs and induces > a VM exit. So VMM can count the number/frequency of bus lock and take > some throttling action or just kill the guest. NB this feedback is not directed at you, but rather the requester of this feature. This request is awful as it exists today. The bugs and upstream commit provide little to no information for apps or libvirt to make sensible decisions on. We shouldn't expose this in libvirt until someone can explain sensible usage policy for applications and why QEMU isn't just setting a sensible value in the machine type by default, given this is claimed to be an important guest denial of service mitigation.. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
