Re: AW: Re: AW: Re: AW: Re: Xen 3.4 strange behaviour as compared to Xen 3.3.1

[Carsten Schiers <carsten@schiers.de>]

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@eu.citrix.com] 
> 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@schiers.de> 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@eu.citrix.com]
>> 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@schiers.de> 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@eu.citrix.com]
>>> 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@schiers.de> 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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