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Re: [Xen-devel] [PATCH 2 of 2] Avoid vcpu migration of paused vcpus

  • To: Keir Fraser <keir@xxxxxxx>
  • From: Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>
  • Date: Fri, 23 Mar 2012 09:17:50 +0100
  • Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Jan Beulich <JBeulich@xxxxxxxx>
  • Delivery-date: Fri, 23 Mar 2012 08:18:03 +0000
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On 03/22/2012 12:20 PM, Keir Fraser wrote:
On 22/03/2012 10:22, "Juergen Gross"<juergen.gross@xxxxxxxxxxxxxx>  wrote:

On 03/22/2012 11:12 AM, Keir Fraser wrote:
Your original patch didn't touch this code. Was that an omission in the
original version? On reflection I prefer your original patch to this new
approach. I'll apply it if you still believe your original patch is complete
and correct as it stands.
I like my second patch more :-)

It covers more cases, not just poweroff. In hibernate case no vcpu pinnings
will be lost. Today all vcpus pinned to a cpu other than 0 will lose their
pinnings at cpu offlining. At reactivation those pinnings will not be
restored automatically. My patch will cover that by checking availability
of the cpus after reactivation.

Poweroff (which was my primary concern) works with both versions. I did not
test other ACPI state changes with either version, but would expect better
results in hibernate case with my second approach.
How about the attached patch? Which is similar to your original patch except
I added the global state variable, and I added a check for it to
cpu_disable_scheduler(). It's nice and small. :-)

Would you mind putting it in 4.1, too?


Juergen Gross                 Principal Developer Operating Systems
PDG 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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