On Thu, Mar 16, 2017 at 12:14:31AM +0300, Vasiliy Tolstov wrote: You can set how much time the VM gets (i.e. limit it), but I'm not sure to what extent will that guarantee stable speed. Unfortunately, there is no way to tell QEMU what the frequency should be in the guest either. I don't think it's possible in KVM. You could, _theoretically_, pin the domain to a specific physical CPUs, and force a specific frequency of those pCPUs using cpufreq. If you are concerned with the speeds, you should also make sure you expose exactly the same CPU model to the guest. Anyway, I would be very careful with interpreting the results in any case. Martin P.S.: I always wondered if I could somehow tell QEMU to advertise slower frequency to the guest. I would even have some use cases for that, I think. If somebody knows, tell me ;)

16 Мар 2017 г. 13:18 пользователь "Daniel P. Berrange" <berrange(a)redhat.com&gt; написал: On Thu, Mar 16, 2017 at 12:14:31AM +0300, Vasiliy Tolstov wrote: There's no way to do this at a KVM or libvirt level. The host kernel will always auto-scale CPU frequency according to the load placed on them by the guest OS (and other processes). To get a fixed frequency,and predictable benchmark results you would have to first use CPUAffinity in systemd.conf (or equiv) to ensure no other OS processes run on a particular chosen CPU. Then strictly bind the guest vCPU to that host CPU. Finally you would have to use sysfs to set the scaling_max_freq/min_freq to contrl what speed your host CPUs ran at. Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://entangle-photo.org -o- http://search.cpan.org/~danberr/ :| Thanks! Next question, does it possible to provide constant speed for vps in case of cloud service? For example user buy vps with 500mhz or 1ghz and pay for guaranteed resource? Weights not very useful because I can't guarantee that each vps have needed processor time...