On Wed, Jun 01, 2022 at 10:59:17AM +0200, Paolo Bonzini wrote: > On 6/1/22 09:57, Vitaly Kuznetsov wrote: > > > > I'll bite... What's ludicrous about wanting to run a guest at a lower CPU freq to minimize observable change in whatever workload it is running? > > > Well, the right API is cpufreq, there's no need to make it a KVM > > > functionality. > > KVM may probably use the cpufreq API to run each vCPU at the desired > > frequency: I don't quite see how this can be done with a VMM today when > > it's not a 1-vCPU-per-1-pCPU setup. > > True, but then there's also a policy issue, in that KVM shouldn't be allowed > to *bump* the frequency if userspace would ordinarily not have access to the > cpufreq files in sysfs. So, when using schedutil (which requires intel_pstate in passive mode), then there's the option to use per-task uclamps which are somewhat complicated but also affect cpufreq.
