On Fri, Dec 03, 2010 at 11:40:27AM +0200, Avi Kivity wrote: > On 12/02/2010 09:14 PM, Chris Wright wrote: > >Perhaps it should be a VM level option. And then invert the notion. > >Create one idle domain w/out hlt trap. Give that VM a vcpu per pcpu > >(pin in place probably). And have that VM do nothing other than hlt. > >Then it's always runnable according to scheduler, and can "consume" the > >extra work that CFS wants to give away. > > What's the difference between this and the Linux idle threads? If we have 3 VMs and want to give them 25% each of a CPU, then having just idle thread would end up giving them 33%. One way of achieving 25% rate limit is to create a "dummy" or "filler" VM, and let it compete for resource, thus rate-limiting everyone to 25% in this case. Essentially we are tackling rate-limit problem by creating additional "filler" VMs/threads that will compete for resource, thus keeping in check how much cpu resource is consumed by "real" VMs. Admittedly not as neat as having a in-kernel support for rate-limit. - vatsa -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
