Fedora xen - Feb 2007 - Re: HVM Performance and PV drivers

On Thursday 08 February 2007 10:08am, Jim Klein wrote: 
> Anyone been able to get the PV drivers from Xensource to work on an 
> FC6 created HVM. Performance is rather sluggish, even on 64bit, 
> without these, yet they don''t seem to want to work here. Or, 
> alternatively, is Red Hat working on their own? The HVM IO is really 
> a bit too slow for most production use without them. 

On Thu, 8 Feb 2007 11:26am, Lamont Peterson wrote: 
> I don''t believe that you can do this. 
> 
>But, I''m wondering what OS you''re trying to run on the HVM
DomU. If it''s
>Linux, use a paravirtualized DomU. You''ll get much better
performance
>(especially on things like I/O). 
> 
>HVM adds some emulation overhead and, thus, is slower than PV. HVM is only 
>necessary to run an OS for which no paravirtualized kernel is available. 
>-- 
>Lamont Peterson <lamont@gurulabs.com> 
>Senior Instructor 
>Guru Labs, L.C. [ http://www.GuruLabs.com/ ] 
All my Linux guests are PV (been running Xen in production for 7 months - far
longer in testing.) I''m talking about Windows guests, which is why I
would need PV drivers to work. Am running 64bit Dom0 to alleviate some of the
pain, but I/O is still too slow for anything but lightweight applications.
We''re a RHEL shop, so would prefer to use RHEL as a base over XenSource
Commercial, but it looks like I may have to go that route if noone else is
working on PV drivers for Windows guests.

-- 
Jim Klein 
Director Information Services & Technology 
LPIC1, CNA/CNE 4-6, RHCT/RHCE 
Saugus Union School District 
http://www.saugus.k12.ca.us 

"Finis Origine Pendet"

On Thu, Feb 08, 2007 at 09:40:50PM -0800, Jim Klein
wrote:
> 
> On Thursday 08 February 2007 10:08am, Jim Klein wrote: 
> > Anyone been able to get the PV drivers from Xensource to work on an 
> > FC6 created HVM. Performance is rather sluggish, even on 64bit, 
> > without these, yet they don''t seem to want to work here. Or, 
> > alternatively, is Red Hat working on their own? The HVM IO is really 
> > a bit too slow for most production use without them. 
> 
> 
> On Thu, 8 Feb 2007 11:26am, Lamont Peterson wrote: 
> > I don''t believe that you can do this. 
> > 
> >But, I''m wondering what OS you''re trying to run on
the HVM DomU. If it''s
> >Linux, use a paravirtualized DomU. You''ll get much better
performance
> >(especially on things like I/O). 
> > 
> >HVM adds some emulation overhead and, thus, is slower than PV. HVM is
only
> >necessary to run an OS for which no paravirtualized kernel is
available.
> >-- 
> >Lamont Peterson <lamont@gurulabs.com> 
> >Senior Instructor 
> >Guru Labs, L.C. [ http://www.GuruLabs.com/ ] 
> 
> All my Linux guests are PV (been running Xen in production for 7 months -
far longer
> in testing.) I''m talking about Windows guests, which is why I
would need PV drivers to work.
> Am running 64bit Dom0 to alleviate some of the pain, but I/O is still too
slow for anything
> but lightweight applications. We''re a RHEL shop, so would prefer
to use RHEL as a base over
> XenSource Commercial, but it looks like I may have to go that route if
noone else is working
> on PV drivers for Windows guests. 
> 
Interesting point is the fact that Novell will ship Windows PV drivers in
SLES 10 SP1 when it''s released in May 2007..

-- Pasi