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

Srivatsa Vaddagiri
2010-12-03T11:57:57Z

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?

- vatsa