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[Xen-devel] CPU Usage Discrepancies

  • To: xen-devel@xxxxxxxxxxxxxxxxxxx
  • From: "Pradeep Vincent" <pradeep.vincent@xxxxxxxxx>
  • Date: Fri, 2 Mar 2007 15:42:48 -0800
  • Delivery-date: Fri, 02 Mar 2007 15:41:57 -0800
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  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>

I see serious discrepancies between Cpu usage as reported by /proc/stat on Xen3
virts and Cpu usage as reported by the hypervisor via "xm" tool
(cpu_time). The problem exists on Intel and AMD platforms - 1 Vcpu and
multiple Vcpu slots - 1 Physical CPU and multiple Physical CPU hosts.

The skew is pronounced with workloads that "sleep-wake-sleep-wake" at
a high frequency while workloads that hog the CPU don't exhibit this
problem as much.

Anybody seen this ? Any insights ?

http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=882 has all the details.

- Pradeep Vincent

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