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Re: [Xen-devel] Hypervisor crash(!) on xl cpupool-numa-split

  • To: Andre Przywara <andre.przywara@xxxxxxx>
  • From: Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>
  • Date: Thu, 10 Feb 2011 07:42:39 +0100
  • Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, "Diestelhorst, Stephan" <Stephan.Diestelhorst@xxxxxxx>
  • Delivery-date: Wed, 09 Feb 2011 22:43:18 -0800
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On 02/09/11 15:21, Juergen Gross wrote:
Andre, George,

What seems to be interesting: I think the problem did always occur when
a new cpupool was created and the first cpu was moved to it.

I think my previous assumption regarding the master_ticker was not too bad.
I think somehow the master_ticker of the new cpupool is becoming active
before the scheduler is really initialized properly. This could happen, if
enough time is spent between alloc_pdata for the cpu to be moved and the
critical section in schedule_cpu_switch().

The solution should be to activate the timers only if the scheduler is
ready for them.

George, do you think the master_ticker should be stopped in suspend_ticker
as well? I still see potential problems for entering deep C-States. I think
I'll prepare a patch which will keep the master_ticker active for the
C-State case and migrate it for the schedule_cpu_switch() case.

Okay, here is a patch for this. It ran on my 4-core machine without any
Andre, could you give it a try?


Juergen Gross                 Principal Developer Operating Systems
TSP ES&S SWE OS6                       Telephone: +49 (0) 89 3222 2967
Fujitsu Technology Solutions              e-mail: juergen.gross@xxxxxxxxxxxxxx
Domagkstr. 28                           Internet: ts.fujitsu.com
D-80807 Muenchen                 Company details: ts.fujitsu.com/imprint.html

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