Re: [Xen-users] Unable to instantiate additional guest domains

[Vittorio Cozzolino <vittorio.cozzolino@xxxxxxxxx>]

Thanks for the reply. I have changed the log level (loglvl=all) of Xen 
and rebooted the machine. Apparently, after rebooting, I managed to 
spawn up to 100 VMs without facing the error I mentioned in previous 
e-mail. When I run the command xl dmesg I don't see anything strange, 
all looks pretty normal. I will try to spawn even more VMs and I'll come 
back to you if the problem reappears.
Thanks again,

Vittorio

Il 21/06/2016 11:48, Wei Liu ha scritto:
> On Wed, Jun 15, 2016 at 10:41:33AM +0100, Vittorio Cozzolino wrote:
> > Hi,
> >
> > I'm currently running some stress tests to figure out how many PVs I can
> > squeeze into my server with Xen. The machine has 64 vcpus (32 physical) and
> > 128 GB RAM. My Domain-0 has 8 vcpus dedicated to it.
> >
> > My basic PV VM is a Linux Alpine DomU with the following settings:
> >
> >
> > # DomU settings
> > memory = 512
> > name = "tiny_alpine_51"
> > vcpus = 2
> > maxvcpus = 2
> >
> > I have reached the point where I have 50 PV of this kind booted and ready.
> > If I try to add more guests domains I receive the following error:
> >
> >
> > libxl: error: libxl_dom.c:301:libxl__build_pre: Couldn't set max vcpu count
> > libxl: error: libxl_create.c:1142:domcreate_rebuild_done: cannot (re-)build
> > domain: -3
> > libxl: error: libxl.c:1591:libxl__destroy_domid: non-existant domain 650
> > libxl: error: libxl.c:1549:domain_destroy_callback: unable to destroy guest
> > with domid 650
> > libxl: error: libxl.c:1476:domain_destroy_cb: destruction of domain 650
> > failed
> >
> > Can anyone help me understand the reason behind such message (machine limit
> > reached?) or how to tune my XEN hypervisor and avoid it?
> Hmm... I myself have tried to boot up 3000 VMs a few years back.  The
> VMs were quite small in terms of memory consumption at the time of my
> experiment but I don't think I encountered error like this.
>
> The call to set max vcpus involves allocating memory from xen heap.  Do
> you see anything interesting in "xl dmesg"?  You may want to increase
> xen's log level to get most information of out it.
>
> Wei.
>
> > Best regards,
> > Vittorio
> >
> >
> >
> > --
> > Vittorio Cozzolino, M.Eng.
> > Technische Universität München - Institut für Informatik
> > Office 01.05.051
> > Boltzmannstr. 3, 85748 Garching, Germany
> > Tel: +49 89 289-17356
> > http://www.cm.in.tum.de/en/research-group/vittorio-cozzolino
>
> > _______________________________________________
> > Xen-users mailing list
> > Xen-users@xxxxxxxxxxxxx
> > http://lists.xen.org/xen-users
--
Vittorio Cozzolino, M.Eng.
Technische Universität München - Institut für Informatik
Office 01.05.051
Boltzmannstr. 3, 85748 Garching, Germany
Tel: +49 89 289-17356
http://www.cm.in.tum.de/en/research-group/vittorio-cozzolino

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