Re: [PATCH] kvm-vmx: add module parameter to avoid trapping HLT instructions (v2)

Chris Wright
2010-12-03T17:28:43Z

* Srivatsa Vaddagiri (vatsa@linux.vnet.ibm.com) wrote:
> On Thu, Dec 02, 2010 at 11:14:16AM -0800, 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.
>
> That's not sufficient. Lets we have 3 guests A, B, C that need to be
> rate limited to 25% on a single cpu system. We create this idle guest
> D that is 100% cpu hog as per above definition. Now when one of the
> guest is idle, what ensures that the idle cycles of A is given only
> to D and not partly to B/C?

Yeah, I pictured priorties handling this.