VM Feature Identification: Difference between revisions
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== MODE DETECTION == |
== MODE DETECTION == |
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The output of the <pre>dmesg</pre> command contains many useful bits of information about the processor mode: |
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From dmesg: |
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=== HVM === |
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If your VM is either HVM or PVHVM, look for: |
If your VM is either HVM or PVHVM, look for: |
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</pre> |
</pre> |
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=== PV === |
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If your VM is PV or PVH, look for: |
If your VM is PV or PVH, look for: |
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<pre> |
<pre> |
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[ 0.000000] Booting paravirtualized kernel on Xen |
[ 0.000000] Booting paravirtualized kernel on Xen |
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</pre> |
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This message indicates that PV timers are in use: |
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<pre> |
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[ 0.000000] Xen: using vcpuop timer interface |
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</pre> |
</pre> |
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Revision as of 16:40, 13 October 2014
When you control your own hypervisor, you are aware of the features you are using, since you have configured the system and the VMs. However, if you are using a service provider for your hosting or cloud, you need to do some detective work to determine the hypervisor mode and features employed.
MODE DETECTION
The output of the
dmesg
command contains many useful bits of information about the processor mode:
HVM
If your VM is either HVM or PVHVM, look for:
[ 0.000000] Hypervisor detected: Xen HVM
PV
If your VM is PV or PVH, look for:
[ 0.000000] Booting paravirtualized kernel on Xen
This message indicates that PV timers are in use:
[ 0.000000] Xen: using vcpuop timer interface
REFERENCES
- A truly great article by Brendan Gregg
