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[Xen-devel] Snmp cpuRawIdle showing double

To: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-devel] Snmp cpuRawIdle showing double
From: Nathan March <nathan@xxxxxx>
Date: Tue, 05 Apr 2011 14:10:16 -0700
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Posted this to xen-users back in Oct
(http://www.gossamer-threads.com/lists/xen/users/186768), but just
confirmed that I'm still seeing this behavior on 4.1.

Polling the UCE-SNMP-MIB::ssCpuRawIdle counter results in a total that's
double the actual number of cpu's on the system, so for example:

nms ~ # snmpwalk -v 2c -c 'XXX' xen1 && sleep 60
&& snmpwalk -v 2c -c 'XXX' xen1
UCD-SNMP-MIB::ssCpuRawIdle.0 = Counter32: 1313274
UCD-SNMP-MIB::ssCpuRawIdle.0 = Counter32: 1324862

(1324862 - 1313274) / 6000 * 100 = 193%

This is polling a dom0 restricted to 1 core using "dom0_max_vcpus=1
dom0_vcpus_pin=true", both proc/cpuinfo and top show only 1 core.

I also see the issue on the domU's, the domU's are running a stock
kernel which does not exhibit this behavior on physical hardware.

This is using stock xen 4.1 with the xen/stable-2.6.32.x kernel, using
net-snmp 5.4.3-r6. Anyone have any insight here or info on how I might
be able to debug this further? I'm not even sure where to look beyond this.


- Nathan

Nathan March <nathan@xxxxxx>
Gossamer Threads Inc. http://www.gossamer-threads.com/
Tel: (604) 687-5804 Fax: (604) 687-5806

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