On Thu, Mar 16, 2017 at 12:14:31AM +0300, Vasiliy Tolstov wrote: > Hi. Does it possible to limit vm cpu speed for example to 1Ghz or 500Mhz ? > I need to simulate some hardware with specific cpu speed and test my > application inside this vm , i want to measure results from each test > and need constant cpu speed for testing (i need to run test not only > my notebook but on server too and want identical cpu speed inside vm) 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/ :| -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
