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. >
