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RE: [Xen-devel] [PATCH] Disable Xen PowerNow! support on Opteron 2nd gen and earlier processors

  • To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>
  • From: "Langsdorf, Mark" <mark.langsdorf@xxxxxxx>
  • Date: Fri, 1 Feb 2008 10:39:56 -0600
  • Cc: Ian Pratt <Ian.Pratt@xxxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx
  • Delivery-date: Fri, 01 Feb 2008 08:56:19 -0800
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AchfqSS0Yzu1EMucEdyNUQAWy6hiGQAC1IswAA/P2j0ABsqr4AB6NDvwABlGPxsAAWGaZgABpF1vAKGkcSA=
  • Thread-topic: [Xen-devel] [PATCH] Disable Xen PowerNow! support on Opteron 2nd gen and earlier processors

> Changeset 16927 should fix the problem for you.

I'm getting about 5 "Time went backwards" messages a day right
now, which is a drastic improvement but still more than I'd 
like.  In three instances, the shadow time value does not

The weird thing is the cpu time values are always of the form:
0: xxxxxx7444952
1: yyyyyy7447746
2: yyyyyy7447746
3: yyyyyy7447746

the y values are usually but not always the same as x or
slightly higher.  When they are different, they differ
by 1000000, 2000000, or 3000000.

I suspect it is related to the fact that platform calibration
is only performed if smp_processor_id() == 0, but I can't
figure out why this is occurring.

-Mark Langsdorf
Operating System Research Center

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