Re: [PATCH] Add I/O hypercalls for i386 paravirt

Benjamin Herrenschmidt
2007-08-28T06:49:53Z

On Wed, 2007-08-22 at 16:25 +1000, Rusty Russell wrote:
> On Wed, 2007-08-22 at 08:34 +0300, Avi Kivity wrote:
> > Zachary Amsden wrote:
> > > This patch provides hypercalls for the i386 port I/O instructions,
> > > which vastly helps guests which use native-style drivers. For certain
> > > VMI workloads, this provides a performance boost of up to 30%. We
> > > expect KVM and lguest to be able to achieve similar gains on I/O
> > > intensive workloads.
> >
> > Won't these workloads be better off using paravirtualized drivers?
> > i.e., do the native drivers with paravirt I/O instructions get anywhere
> > near the performance of paravirt drivers?
>
> This patch also means I can kill off the emulation code in
> drivers/lguest/core.c, which is a real relief.

Hrm... how do you deal with X doing IOs ?

Ben.