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

Marcelo Tosatti
2010-12-03T18:14:09Z

On Fri, Dec 03, 2010 at 09:58:54AM -0800, Chris Wright wrote:
> * Srivatsa Vaddagiri (vatsa@linux.vnet.ibm.com) wrote:
> > On Fri, Dec 03, 2010 at 09:29:06AM -0800, Chris Wright wrote:
> > > That's what Marcelo's suggestion does w/out a fill thread.
> >
> > There's one complication though even with that. How do we compute the
> > real utilization of VM (given that it will appear to be burning 100% cycles)?
> > We need to have scheduler discount the cycles burnt post halt-exit, so more
> > stuff is needed than those simple 3-4 lines!
>
> Heh, was just about to say the same thing ;)

Probably yes. The point is, you get the same effect as with the
non-trapping hlt but without the complications on low-level VMX/SVM
code.

Even better if you can do it with fill thread idea.