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Re: BUG: credit=sched2 machine hang when using DRAKVUF


  • To: Jürgen Groß <jgross@xxxxxxxx>
  • From: Michał Leszczyński <michal.leszczynski@xxxxxxx>
  • Date: Sat, 24 Oct 2020 01:36:09 +0200 (CEST)
  • Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
  • Delivery-date: Fri, 23 Oct 2020 23:36:19 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
  • Thread-index: ehjKdI2aZ/NIQ0mvEFcfZJ714jsIjw==
  • Thread-topic: credit=sched2 machine hang when using DRAKVUF

----- 23 paź, 2020 o 6:47, Jürgen Groß jgross@xxxxxxxx napisał(a):

> On 23.10.20 00:59, Michał Leszczyński wrote:
>> Hello,
>> 
>> when using DRAKVUF against a Windows 7 x64 DomU, the whole machine hangs 
>> after a
>> few minutes.
>> 
>> The chance for a hang seems to be correlated with number of PCPUs, in this 
>> case
>> we have 14 PCPUs and hang is very easily reproducible, while on other 
>> machines
>> with 2-4 PCPUs it's very rare (but still occurring sometimes). The issue is
>> observed with the default sched=credit2 and is no longer reproducible once
>> sched=credit is set.
> 
> Interesting. Can you please share some more information?
> 
> Which Xen version are you using?

RELEASE-4.14

> 
> Is there any additional information in the dom0 log which could be
> related to the hang (earlier WARN() splats, Oopses, Xen related
> messages, hardware failure messages, ...?

I will try to find something out next week and will come back to you.

> 
> Can you please try to get backtraces of all cpus at the time of the
> hang?
> 
> It would help to know which cpu was the target of the call of
> smp_call_function_single(), so a disassembly of that function would
> be needed to find that information from the dumped registers.
> 
> I'm asking because I've seen a similar problem recently and I was
> rather suspecting a fifo event channel issue than the Xen scheduler,
> but your data suggests it could be the scheduler after all (if it is
> the same issue, of course).
> 
> 
> Juergen



 


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