Re: AW: Re: AW: Re: AW: Re: [Xen-devel] Xen 3.4 strange behaviour as compared to Xen 3.3.1

[Carsten Schiers <carsten@xxxxxxxxxx>]

By the way: in the forum of my favorite distro (c't Server), I found 
another guy with exactly
the same problem. 3.3.1 working, 3.4 no stepping up.

BR,
Carsten.

Carsten Schiers schrieb:
> No it's the kernel of Xen 3.4.0 with the same config. I will try later 
> with the 
> older kernel, which is the one of 06.04.2009 (I have not realy 
> understood the
> tagging or versioning of the Xen kernel). The other combination would be 
> Xen 3.3.1
> with the latest kernel. That's how we narrow it down to hypervisor vs. 
> kernel.
> As I use cpufreq=dom0-kernel and enable cpufreq modules in 
> drivers/cpufreq/Kconfig,
> I guess it should use the hypercall for idle time. But to double check, 
> I generated
> load in dom0. No difference. It simply doesn't step upwards. The kernel 
> with cpufreq
> debugging is enabled. I will also try it, maybe it's loging something 
> usefull.
> BR,
> Carsten.
>
> -----Ursprüngliche Nachricht-----
> Von: Keir Fraser [mailto:keir.fraser@xxxxxxxxxxxxx] 
> Gesendet: Samstag, 30. Mai 2009 11:30
> An: Carsten Schiers; xen-devel
> Betreff: Re: AW: Re: AW: Re: [Xen-devel] Xen 3.4 strange behaviour as 
> compared to Xen 3.3.1
> Are you using the exact same dom0 kernel as before, when it worked? One
> theory would be that dom0 is looking at its own idle stats, and it 
> probably
> is pretty idle. So then it steps down the CPUs and keeps them down. When 
> you
> work the CPUs, are you working dom0 hard?
>
>  -- Keir
>
> On 30/05/2009 07:59, "Carsten Schiers" <carsten@xxxxxxxxxx> wrote:
>
>   
> > Sorry, it's lowest frequency (1.0 out of 1.0, 1.8, 2.0, and 2.1 GHz).
> > When booting,
> > the CPU will be at 2.1 GHz, when switching the governor from 
> >     
> performance
>   
> > to ondemand,
> > this one will set it to 1.0 GHz, where it's sort of fixed. I can set 
> >     
> it
>   
> > manually with
> > cpufreq-set when switching to userspace governor, though.
> >
> > So my guess is that the ondemand governor donesn't get te right
> > information about idle
> > time though the according hypercall. I recompiled with CPUFREQ DEBUG
> > set. But as said
> > earlier, I don't have that much knowledge about how to debug kernels.
> >
> > BR,
> > Carsten.
> >
> > -----Ursprüngliche Nachricht-----
> > Von: Keir Fraser [mailto:keir.fraser@xxxxxxxxxxxxx]
> > Gesendet: Freitag, 29. Mai 2009 23:31
> > An: Carsten Schiers; xen-devel
> > Betreff: Re: AW: Re: [Xen-devel] Xen 3.4 strange behaviour as compared
> > to Xen 3.3.1
> >
> > Is lowest p-state lowest or highest frequency/voltage?
> >
> >  -- Keir
> >
> > On 29/05/2009 17:47, "Carsten Schiers" <carsten@xxxxxxxxxx> wrote:
> >
> >     
> > > Thanks Keir, I tried it out but there is no difference. And by the
> > >       
> > way:
> >     
> > > it
> > > is in lowest p-state and doesn't come up, even if under heavy load.
> > >       
> > Hmm.
> >     
> > > BR,
> > > Carsten.
> > >
> > > -----Ursprüngliche Nachricht-----
> > > Von: Keir Fraser [mailto:keir.fraser@xxxxxxxxxxxxx]
> > > Gesendet: Freitag, 29. Mai 2009 17:02
> > > An: Carsten Schiers; xen-devel
> > > Betreff: Re: [Xen-devel] Xen 3.4 strange behaviour as compared to Xen
> > > 3.3.1
> > >
> > > On 29/05/2009 15:03, "Carsten Schiers" <carsten@xxxxxxxxxx> wrote:
> > >
> > >       
> > > >   - as already reported, ondemand manager in dom0-kernel doesn't
> > > >         
> > step,
> >     
> > > > manual
> > > >     setting works so it seems a bit like the communication between
> > > >         
> > > dom0
> > >       
> > > > and
> > > >     hypervisor regarding idle time is not working
> > > >         
> > > Could be an interaction with C-state support, preferring deep sleep 
> > >       
> to
>   
> > > running at lower voltage/frequency? You could try no-cpuidle on Xen's
> > > command line at boot time and see if that changes things.
> > >
> > >  -- Keir
> > >
> > >       
> > > >   - all beside one domu use Xen 3.4.0 kernel, the one who uses it's
> > > > customized
> > > >     kernel won't start up as first domu. It simply hangs and this
> > > > prevents also
> > > >     all other domus (I all auto start them, no save/restore) don't
> > > >         
> > > come
> > >       
> > > > up. When
> > > >     I start the chain with a different one and this (with the
> > > >         
> > > different
> > >       
> > > > kernel)
> > > >     is started as #2 or #3, not problem
> > > >
> > > >   - one domu is for vdr with three dvb pci cards passed trough. This
> > > > one, when
> > > >     started as the first one, will cause xentop to show 20% load.
> > > >         
> > When
> >     
> > > > restarted
> > > >     or started as #2, the load is like with 3.3.1 at roughly 3-5%.
> > > >         
> > >       
> >     
>
>
>
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