Re: problems running many guests

[Marcelo Tosatti <mtosatti@redhat.com>]

Hi Karl,

On Mon, May 05, 2008 at 08:40:22PM -0500, Karl Rister wrote:
> On Thursday 01 May 2008 7:16:53 pm Marcelo Tosatti wrote:
> > Does -no-kvm-irqchip or -no-kvm-pit makes a difference? If not, please
> > grab kvm_stat --once output when that happens.
> 
> Per some suggestions I have moved up to kvm-68 which is better, but still 
> having problems.  Replicating the problem with only one guest spinning has 
> proven quite difficult, but attempting to boot a large smp guest can reliably 
> recreate the problem.  Using -no-kvm-pit did not help the large guest 
> and -no-kvm-irqchip made it seize up even earlier with only 1 cpu spinning 
> instead of all of them.
> 
> >
> > Also run "readprofile -r ; readprofile -m System-map-of-guest.map" with the
> > host booted with "profile=kvm". Make sure all guests are running the same
> > kernel image.
> 
> I got this from a spinning 16-way guest with only 8 of the host CPUs online 
> and without either -no-kvm-irqchip or -no-kvm-pit:
> 
> [root@newcastle ~]# readprofile -r ; readprofile -m 
> karl/System.map-2.6.25-03591-g873c05f
>    101 native_read_tsc                            3.4828
>      1 read_persistent_clock                      0.0192
>     25 kvm_clock_read                             0.2660
>     95 getnstimeofday                             0.7252
>     13 update_wall_time                           0.0138
>      1 second_overflow                            0.0020
> readprofile: profile address out of range. Wrong map file?

KVM clock has known problems with SMP guests, please disable it for now.

Also disable LOCKDEP on the guest if it has more VCPU's than CPU's
available in the host.


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