RE: [Xen-users] major slow down with xen implementation

["Ross S. W. Walker" <RWalker@xxxxxxxxxxxxx>]

Grant McWilliams wrote:
> 
> On Thu, Sep 25, 2008 at 10:16 AM, Javier Guerra <javier@xxxxxxxxxxx> wrote:
> 
>       On Thu, Sep 25, 2008 at 11:55 AM, Geoffrey 
> <lists@xxxxxxxxxxxxxxxxxxxxx> wrote:
>       > Can't para-virtualize.  Running 64bit on the hardware so as to get 
> access to
>       > the full 32GB memory.  Running 32bit virtuals, because we have a 
> third party
>       > app that won't run on 64bit.  I know...
>       
>       
>       it's not easy to write a 32bit app that won't run when the needed
>       libraries are there; but i guess you're already tired of analysing ldd
>       output.
> 
> I'd assume that you've tried providing the relevant 32 bit 
> libraries for the app but it's dangerous to assume anything 
> so I won't. You can get most
> 32 bit apps to run on 64 bit if you have both 32 bit and 64 
> bit libs available. I think it's worth the effort. But again 
> you've probably already gone down
> this route.  The overhead for HVM is quite a bit higher than PV. 
> 
> Also according to the Xensource wiki you can install a 32bit 
> PAE PV on a 64bit DomU Hypervisor with Xen 3.1 and greater.

Yes, and since RHEL Xen 3.0.3 is really the 3.1 hypervisor with
the 3.0.3 userland utils (don't ask) and since the RHEL kernels
are now all PAE you should be able to run your 32bit PV domU on
your 64bit dom0.

Plus with pyGrub boot loading you don't need to re-image to
try it out, hell if your using LVM you don't even need to
take your existing domU down to test, just snapshot it.

Install the Xen domU kernel in your HVM guest side-by-side with
your native kernel, make an LVM snapshot, create a PV config
for it and try to boot it (remember to console at boot so you
can choose the Xen kernel). If it doesn't work it will stop
right after the Xen 3.1 banner, if it does then you can plan
on switching to PV during the next maintenance period.

NOTE: Remember to either not allocate or attach to a loop
tap device the network interface of the test PV to prevent
duplicate IP addresses.

-Ross

______________________________________________________________________
This e-mail, and any attachments thereto, is intended only for use by
the addressee(s) named herein and may contain legally privileged
and/or confidential information. If you are not the intended recipient
of this e-mail, you are hereby notified that any dissemination,
distribution or copying of this e-mail, and any attachments thereto,
is strictly prohibited. If you have received this e-mail in error,
please immediately notify the sender and permanently delete the
original and any copy or printout thereof.


_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users