Re: [gentoo-server] Toughts on Virtualization

[Hacking Networked Solutions - Gentoo List Subscriptions]

On Tue, 2012-04-10 at 07:28 +0700, Pandu Poluan wrote:
>
> On Apr 10, 2012 7:15 AM, "Hacking Network Solutions - Gentoo List
> Subscriptions" <gentoo.lists@××××××××××.uk> wrote:
> >
> > On Mon, 2012-04-09 at 19:32 +0300, Konstantin wrote:
> > >
> > > What kernel versions are you using for Dom0? Today I've tried to
> use
> > > sys-kernel/gentoo-sources-3.2.12 and couldn't find any backend
> driver
> > > support. Am I missed something? ;)
> > >
> >
> > Hi Konstantin,
> >
> > I use Xen with Gentoo for both Dom0 and DomU.
> >
> > The back-end driver support is well hidden in the menus,
> >
> > Device Drivers  --->  Xen driver support  --->  Backend driver
> support
> >
> > is required to show them.
> >
> > I have attached a working .config 3.2.12 for your convenience.
> >
> > My company also maintains a (still unfinished and now slightly out
> of
> > date unfortunately, but it is on my list of things to update)
> document
> > related to using Xen with Gentoo here:
> >
> >
> http://www.mad-hacking.net/documentation/linux/deployment/xen/index.xml
> >
>
> OMG! You're working there? Hats off to you guys, and max respect!
>
> I would never be able to deploy my Gentoo infrastructure had I not
> read this :
>
> http://www.mad-hacking.net/documentation/linux/deployment/buildserver/index.xml
>
Thank you for the kind words - it's always nice to know that we've been
able to help, especially with getting Gentoo more widely deployed in
production/corporate environments.

> > We also maintain ebuilds for the 4.0.2 branch of Xen in our overlay,
> > which can be installed with layman (hacking-gentoo).
> >
> > Maybe this will be of some help, I hope so - if you have any
> problems
> > with Xen feel free to ask me.
> >
> > If you have any issues with the docs/ebuilds please email me off
> list.
> >
>
> Not an issue, just an honest question: Does having Gentoo as Dom0
> significantly improve performance?
>
I wish I could say - unfortunately we've only ever used Gentoo as our
Dom0 distribution so have nothing to compare it against.

Theoretically, distributions which are specifically customised for use
as a Xen Dom0 _could_ be better from a performance standpoint as no
doubt there must be some optimisations which can be made that would not
be suitable for a more generic distribution.  

That said I would be very interested to know if any of them had actually
been optimised in said fashion and if the requirements to still run as
wide a range of software as possible on the Dom0 (equivalent to loads of
USE flags) on a wide range of similar processors (equivalent to very
generic CPU setting) actually hurts enough to still make Gentoo a better
choice.  

My _guess_ is that it would, although we're probably talking fractions
of a percent here not significant improvements unless the more generic
distributions pay a particularly heavy price for their CPU tolerance.

Max