Re: [Qemu-devel] [PATCH v3] Throttle-down guest when live migration does not converge.

[Chegu Vinod]

On 5/1/2013 8:40 AM, Paolo Bonzini wrote:
> > I shall make the suggested changes.
> > Appreciate your review feedback on this part of the change.
Hi Paolo.,

Thanks for taking a look (BTW, I accidentally left out the "RFC"  in the 
patch subject line...my bad!).
> Hi Vinod,
>
> I think unfortunately it is not acceptable to make this patch work only
> for KVM.  (It cannot work for Xen, but that's not a problem since Xen
> uses a different migration mechanism; but it should work for TCG).

Ok. I hadn't yet looked at TCG aspects etc. Will follow up offline...

> Unfortunately, as you noted the run_on_cpu callbacks currently run
> under the big QEMU lock.  We need to fix that first.  We have time
> for that during 1.6.

Ok.  Was under the impression that anytime a vcpu thread enters to do 
anything in qemu the BQL had to be held. So choose to go with 
run_on_cpu()  .  Will follow up offline on alternatives

"Holding" the vcpus in the host context (i.e. kvm module) itself is 
perhaps another way. Would need some handshakes (i.e. new ioctls ) with 
the kernel. Would that be acceptable way to proceed?

Thanks
Vinod

> Paolo
> .