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

[Zachary Amsden]

Benjamin Herrenschmidt wrote:
> 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.
>   

We have an X driver that does minimal performance costing operations.  
As we should and will have for our other drivers.

Zach

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