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Re: [Xen-devel] Xen 4.5 random freeze question



On Wed, Nov 19, 2014 at 3:26 PM, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
> On 11/19/2014 12:40 PM, Andrii Tseglytskyi wrote:
>> Hi Julien,
>>
>> On Wed, Nov 19, 2014 at 2:23 PM, Julien Grall <julien.grall@xxxxxxxxxx> 
>> wrote:
>>> On 11/19/2014 12:17 PM, Stefano Stabellini wrote:
>>>> On Wed, 19 Nov 2014, Ian Campbell wrote:
>>>>> On Wed, 2014-11-19 at 11:42 +0000, Stefano Stabellini wrote:
>>>>>> So it looks like there is not actually anything wrong, is just that you
>>>>>> have too much inflight irqs? It should cause problems because in that
>>>>>> case GICH_HCR_UIE should be set and you should get a maintenance
>>>>>> interrupt when LRs become available (actually when "none, or only one,
>>>>>> of the List register entries is marked as a valid interrupt").
>>>>>>
>>>>>> Maybe GICH_HCR_UIE is the one that doesn't work properly.
>>>>>
>>>>> How much testing did this aspect get when the no-maint-irq series
>>>>> originally went in? Did you manage to find a workload which filled all
>>>>> the LRs or try artificially limiting the number of LRs somehow in order
>>>>> to provoke it?
>>>>>
>>>>> I ask because my intuition is that this won't happen very much, meaning
>>>>> those code paths may not be as well tested...
>>>>
>>>> I did test it by artificially limiting the number of LRs to 1.
>>>> However there have been many iterations of that series and I didn't run
>>>> this test at every iteration.
>>>
>>> am I the only to think this may not be related to this bug? All the LRs
>>> are full with IRQ of the same priority. So it's valid.
>>>
>>> As gic_restore_pending_irqs is called every time that we return to the
>>> guest. It could be anything else.
>>>
>>> It would be interesting to see why we are trapping all the time in Xen.
>>>
>>
>> I may perform any test if you have some specific scenario.
>
> I have no specific scenario in my mind :/.
>
> It looks like I'm able to reproduce it on my ARM board by the restricted
> the number of LRs to 1.
>

Do you mean that you got a hang with current xen/master branch ?

Regards,
Andrii

> I will investigate.
>
> Regards,
>
> --
> Julien Grall



-- 

Andrii Tseglytskyi | Embedded Dev
GlobalLogic
www.globallogic.com

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