Hi,

Please watch this 4-minute video at
http://www.youtube.com/watch?v=LbLaPpwNAx4

I have only started 3 HVM Linux guests with 1 GB ram each. I can't start the
4th HVM guest. If I attempt to start the 4th instance, it will crash dom0.

Are there anything in the xm dmesg output that could explain the low limit
to the number of VMs that I could start before dom0 becomes unresponsive?

Thank you.

-- 
Mr. Teo En Ming (Zhang Enming) Dip(Mechatronics) BEng(Hons)(Mechanical
Engineering)
Alma Maters:
(1) Singapore Polytechnic
(2) National University of Singapore
My Primary Blog: http://teo-en-ming-aka-zhang-enming.blogspot.com
My Secondary Blog: http://enmingteo.wordpress.com
My Youtube videos: http://www.youtube.com/user/enmingteo
Email: space.time.universe@gmail.com
Mobile Phone (Starhub Prepaid): +65-8369-2618
Street: Bedok Reservoir Road
Country: Singapore

On Mon, Nov 9, 2009 at 4:17 PM, Robert Dunkley <Robert@saq.co.uk> wrote:

> There seems to also be a limit imposed by CPU context switching. Ie. Once
> you have enough VMs trying to grab a cpu core things come to a standstill as
> the cpu spends most of its time switching rather than processing. The most
> common bottleneck I find is disk performance but this depends hugely on what
> your VMs are doing.
>
> -----Original Message-----
> From: xen-users-bounces@lists.xensource.com [mailto:
> xen-users-bounces@lists.xensource.com] On Behalf Of Moi meme
> Sent: 08 November 2009 13:02
> To: Mr. Teo En Ming (Zhang Enming)
> Cc: xen-devel@lists.xensource.com; xen-users@lists.xensource.com
> Subject: Re: [Xen-users] Max. PV and HVM Guests
>
> Hello,
>
> The maximum is a direct function of the available memory, every new
> machine "eats" some memory and when there is no more memory ......
> I had some servers (64bits, 2 quad core and 32Gb Ram) running 19 VM,
> 2003 server, 2000 Server,Fedora, Debian all in 32bits.
> In my own system I have tested with upto 10 VMs of 512M each without
> breaking the system.
>
> Regards
>
> JP Pozzi
>
> Le dimanche 08 novembre 2009 à 19:45 +0800, Mr. Teo En Ming (Zhang
> Enming) a écrit :
> > Hi,
> >
> > I have observed that there is a maximum limit to the number of PV or
> > HVM virtual machines you can start before dom0 hangs or crashes.
> >
> > For Fedora 11 Linux x86-64 PV guests, dom0 will crash when I start the
> > 7th instance. Max I can start is 6 without crashing.
> >
> > For CentOS 5.2 Linux x86-64 HVM guests, dom0 will crash when I start
> > the 4th instance. Max I can start is 3 without crashing.
> >
> > I have 6 GB of DDR2-800 with Intel Pentium Dual Core E6300 2.8 GHz on
> > Intel DQ45CB motherboard.
> >
> > Are the above limits reasonable considering the hardware
> > specifications of my computer?
> >
> > I am using Xen 3.5-unstable changeset 20143 with pv-ops dom0 kernels
> > 2.6.30-rc3, 2.6.31-rc6, 2.6.31.1, 2.6.31.4, and 2.6.31.5. My host
> > operating system is Fedora 11 Linux x86-64.
> >
> > --
> > Mr. Teo En Ming (Zhang Enming) Dip(Mechatronics) BEng(Hons)(Mechanical
> > Engineering)
> > Alma Maters:
> > (1) Singapore Polytechnic
> > (2) National University of Singapore
> > My Primary Blog: http://teo-en-ming-aka-zhang-enming.blogspot.com
> > My Secondary Blog: http://enmingteo.wordpress.com
> > My Youtube videos: http://www.youtube.com/user/enmingteo
> > Email: space.time.universe@gmail.com
> > Mobile Phone (Starhub Prepaid): +65-8369-2618
> > Street: Bedok Reservoir Road
> > Country: Singapore
> > _______________________________________________
> > Xen-users mailing list
> > Xen-users@lists.xensource.com
> > http://lists.xensource.com/xen-users
>
>
>
>
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