On 12/05/2018 00:12, Michael S. Tsirkin wrote:
>> Maybe it's a better idea than overloading an option that is only
>> expected to control a CPUID bit.
> Well -realtime would be a bit confusing in that it enables mlock by
> default.
Currently, the only suboption of "-realtime" is mlock, which means that
the only three valid uses of it are
-realtime mlock=on
-realtime mlock=off
-realtime ''
We can change the default, I think. Only the third would change
meaning, and it's a slightly crazy way to use the option.
> From pure API point of view, hint-dedicated looks good since
> it seems to say "optimize for a dedicated host CPU" and
> it's a hint in that guests keep working if you violate this
> slightly once in a while.
>
> But I agree there's a problem: right now "kvm-" means "KVM PV"
> as opposed to e.g. HV enlightened gusts.
> So if you enable hyperv and also want to disable halt existing,
> what then? What should kvm-hint-dedicated=on do?
kvm-hint-dedicated=on only sets the CPUID bit, which Linux for example
uses that to disable pv spinlocks. "-realtime dedicated-cpus=on" only
disables the vmexits. You can use the two independently.
Thanks,
Paolo
> So how about a new hint-dedicated=on cpu flag? We can have that set
> kvm-hint-dedicated if kvm PV is enabled.
>
