Re: [Xen-users] x64 hvm linux very slow on a x64 xen host

[Matthieu Patou <mat+Informatique.xen@xxxxxxxxx>]

On 20/01/2010 13:23, Pasi Kärkkäinen wrote:
> On Wed, Jan 20, 2010 at 01:06:32PM +0300, Matthieu Patou wrote:
>    
> > On 20/01/2010 12:47, Pasi Kärkkäinen wrote:
> >      
> > > On Wed, Jan 20, 2010 at 11:30:37AM +0300, Matthieu Patou wrote:
> > >
> > >        
> > > > Hello,
> > > >
> > > > I'm trying to use Fedora x64 on a xen x64 host in hvm mode and the domU
> > > > is _very_ slow.
> > > > I am wondering if there is any tunning possible ?
> > > >
> > > >
> > > >          
> > > You'd have to pv-on-hvm drivers to get good IO performance.
> > >
> > >        
> > Where can I get them ?
> >
> >      
> What Fedora version are you using? What kernel?
>    
So it's an install from the live cd of Fedora 12 x64.
>    
> > > Other (easier) option is to use Fedora PV guest, instead of HVM.
> > >
> > >
> > >        
> > Yeah I'm thinking about converting my image to PV but I was just
> > wondering why is so slow ...
> > Note that fedora i386 do not look so slow on the same xen x64 host
> >
> >      
> Yeah that's weird..
>
> Did you measure Xen cpu usage with "xm top" in dom0?
>
>    
Not yet i'll retry soon. I'll let you know.
> What's using the CPU?
> Is there any load on dom0? Check with "top".
>
> How did you measure the HVM guest is slow?
>
>    
Because compiling samba 4 in this host takes ages although in fedora 386 
with the same code the speed is way better.
Matthieu.

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