Re: [libvirt] [Qemu-devel] pvpanic plans?
On Thu, Aug 22, 2013 at 03:09:06PM -0500, Anthony Liguori wrote:
Paolo Bonzini <pbonzini(a)redhat.com> writes:
> Also, a virtio watchdog device makes little sense, IMHO. PV makes sense
> if emulation has insufficient performance, excessive CPU usage, or
> excessive complexity. We already have both an ISA and a PCI watchdog,
> and they serve their purpose wonderfully.
Neither of which actually work with modern versions of Windows FWIW.
Correct, although someone could write a driver!
Plus emulated watchdogs do not take into account steal time or
overcommit in general. I've seen multiple cases where a naive watchdog
has a problem in the field when the system is under heavy load.
The watchdog devices in qemu run on guest time. However the watchdog
*daemon* inside the guest probably does behave badly as you describe.
Changing the device model isn't going to help this, but it would
definitely make sense to fix the daemon (although I don't know how --
is steal time exposed to guests?)
I don't necessarily think a virtio-watchdog is a bad idea. For one
thing it'd mean we would have a watchdog device that works on ARM.
Rich.
--
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