Re: Fwd: KVM and cpu limiting

[Srivatsa Vaddagiri <vatsa@in.ibm.com>]

> Is it possible to limit cpu usage be VM when using qemu+kvm?

Have you checked cpu controller?

	# mkdir /cpu_control
	# mount -t cgroup -o cpu none /cpu_control

	# cd /cpu_control
	# mkdir vm1
	# mkdir vm2

Then change vm{1,2}/cpu.shares to control how much proportion of CPU capacity
each VM gets. Basically, each vm is (soft-)limtied to:

	its allocated shares / total shares allocated for all VMs.

> I need one server to run a lot of VMs (much more than cpu cores I
> have). Each VM must have it's guaranted cpu time or time slice it must
> use.

This interface is more focused on limiting resource consumption rather than
guaranteeing certain minimum. By carefully controlling how many VMs are run on
the server and how many shares are allocated to each, this can be a good
alternative to provide some "minimum" resources to a VM. Its slightly inflexible
for guaranteeing "minimum" resource to a VM, but that's the best we have now.

> Is it possible to make such limits? Is it possible to modify
> /proc/cpuinfo of VMs?

Why do you want to modify /proc/cpuinfo of VMs?

- vatsa