Re: [Xen-users] Running Xen 2.0 for Counter Strike: Source

[Ralph Passgang <ralph@xxxxxxxxxxxxx>]

Am Mittwoch, 15. Februar 2006 15:58 schrieb Bart van den Heuvel:
> The choice for Xen 2 was mostly because of a network issue discussed in
> this list some time ago (by Falko Timme). I believe this issue is still
> open.
> http://lists.xensource.com/archives/html/xen-users/2006-01/msg00504.html

don't know, never experience something like that on my xen3 debian machines.

> I have a question open in this list about upgrading. I would like to give
> 3 a go offcourse. However i would hate the idea to do a complete clean
> reinstall of Debian.

That shouldn't be needed in the most cases.

> Is there somekind of hint on upgrading from 2 to 3? 
> Using the .deb packages i figure that i would just move all the 2.0 stuff
> of the system and install the .deb packs overwriting the prior install of
> 2.0.8 from source.

yes, you should remove all old 2.0 stuff from your system and then install the 
xen3 packages. typing "apt-get install xen" should be enough if you have 
added the correct lines to your sources.list.

then if you want to compile your own kernel I would suggest taking a look at:
 http://www.debian-administration.org/articles/320

otherwise also install the "linux-xen0-2.6" package. there will be some hints 
that gets shown on installation. just the regular stuff like updating grub's 
menu.list, generating an initrd and copying the modules to the domU 
filesystems.

that should be all... if you want to downgrade again, then you would have to 
remove the packages again and install old 2.0.7 or 2.0.8 packages (or 
recompile it from source again).

there are just some things that have really changes. I think "xen-br0" was the 
default bridge name in xen2 and in xen3 it's "xenbr0". Also you shouldn't use 
"nics = X" and the vcpu/cpu syntax has changed a bit. I think that's it. 

> Hahaa lots of questions :-)

If you don't want to compile your own kernel for xen3, then I guess upgrading 
is not taking as long as if you just would recompile your xen2 kernel 
again :)

>
> Gr,
>
> Bart
>
> > Why don't you try xen3? Even if there is no performance benefit, it would
> > help
> > you to stay up2date with the recent development. But maybe even xen3
> > solves
> > some performance issues without the need for further tweaking.
> >
> > you are using debian? I would suggest taking a look at the following
> > post:
> > http://lists.xensource.com/archives/html/xen-users/2006-01/msg00641.html
> >
> > --Ralph
> >
> > Am Mittwoch, 15. Februar 2006 14:40 schrieb Bart van den Heuvel:
> >> Only changed the 100 hz setting to 1000 hz and turned Big mem support
> >> (4gb) on for both the dom0 and domU kernels. I configured the virtual
> >> machine to have 1000mb memory, it only used 830 meg or so without the
> >> big
> >> mem option.
> >> That's viseble in the graph at the bottom of
> >> http://core.zokahn.com/cs-01/
> >>
> >> 75 fps is not a big deal! other systems run with 200 - 500 fps but it's
> >> a
> >> start! And if my players are happy...
> >>
> >> I will still try and boot to a normal debian kernel and run the same
> >> gameservers (they can run on the same machine) and test the difference
> >> between the Xen and the Normal world.
> >>
> >> Gr,
> >>
> >> Bart
> >>
> >> > Did you change anything else to get this or only to 1000HZ?
> >> >
> >> > John
> >> >
> >> > -----Original Message-----
> >> > From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
> >> > [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Bart van
> >>
> >> den
> >>
> >> Heuvel
> >>
> >> > Sent: Wednesday, February 15, 2006 6:17 AM
> >> > To: Ernst Bachmann
> >> > Cc: xen-users@xxxxxxxxxxxxxxxxxxx
> >> > Subject: Re: [Xen-users] Running Xen 2.0 for Counter Strike: Source
> >> >
> >> > Ernst,
> >> >
> >> > I see what you mean, if your thougts prove to be true than vserver
> >>
> >> would
> >>
> >> be more of an option, i would hate to leave xen the concept is very
> >> attractive.
> >>
> >> > Now that i look at my graphs again I see a very different picture!
> >> >
> >> > Please check http://core.zokahn.com/cs-01/
> >> >
> >> > FPS is way up! I must be going MAD....
> >> >
> >> > Thanks!
> >> >
> >> > Bart
> >> >
> >> >> On Wednesday 15 February 2006 10:37, Bart van den Heuvel wrote:
> >> >>> I have recompiled the kernels, both dom0 and domU. Counterstrike
> >> >
> >> > comes
> >> >
> >> >>> in
> >> >>> a compiled form (silly enterprises still do that :-)
> >> >>>
> >> >>> All is wel and i got the change to compile in the bigmem option! So
> >> >
> >> > i'm
> >> >
> >> >>> very happy there. I can now use more mem for my virtual servers...
> >> >
> >> > But
> >> >
> >> >>> thats where the happyness stops!
> >> >>>
> >> >>> Instead of a performance upgrade fps is now steady on 1, so the 1000
> >> >
> >> > hz
> >> >
> >> >>> options made the fps value go from 50 to 1 instead of a higher
> >>
> >> value.
> >>
> >> >>> I'm running like this for a few hours... Maybe more inspiration will
> >> >>> come to me.
> >> >>
> >> >> The HZ Value sets how often timer interrups occur, so instead of
> >>
> >> interrupting
> >>
> >> >> work 250 times a second, you now interrupt it 1000 times.
> >> >>
> >> >> I guess timer interrupts in xen are more expensive than on plain
> >> >
> >> > linux,
> >> >
> >> >> since
> >> >> they also involve the hypervisor (correct me if I'm wrong here)
> >> >>
> >> >> if three domains use the same cpu, xen needs to switch the running
> >> >
> >> > domain
> >> >
> >> >> 3000
> >> >> times a second, I guess you waste a lot of cycles there.
> >> >>
> >> >> Another reason (wild guess) could be: the hypervisor still generates
> >>
> >> interrupts at 250HZ, but now the domU kernel now expects them coming
> >>
> >> > at
> >> >
> >> >> 1000Hz, hence the internal timing of the kernel is way off, resulting
> >> >
> >> > of
> >> >
> >> >> the
> >> >> timing source of your CS server working only on full seconds now => 1
> >>
> >> frame
> >>
> >> >> per second max...
> >> >>
> >> >> For applications requiring short response time, a "lesser"
> >> >
> >> > virtualization
> >> >
> >> >> method, like linux-vserver, might provide much better performance.
> >> >>
> >> >> /Ernst
> >> >>
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> >> >
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> >> >
> >> >
> >> >
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