On 08/27/13 11:44, Peeyush Gupta wrote:
> Hi,
>
Hi,
> I have been trying to find out CPU topology using libvirt.
> I understand that I can find out the number of cores/sockets/
> threads etc through getCapabilities() function. What I am wondering
> is that is there any function that can provide me the exact topology
> like how many sockets, how many sockets per core and number of
> threads per core, if applicable or may be info about numa cells.
> Is there any mechanism to achieve this?
libvirt-1.0.2 contains an extended output [1] in the capabilities XML that
closer describes the individual CPUs seen by libvirt. This data can then
be used to extract data about the host topology.
I'll try to find and add to examples a python script that can be used
to do the calculation from the data in the capabilities XML.
>
> Thanks,
>
> ~Peeyush Gupta
>
>
Peter
[1]:
commit 828820e2d371205d6a6061301165d58a1a92e611
Author: Peter Krempa <pkrempa@xxxxxxxxxx>
Date: Fri Jan 18 19:30:00 2013 +0100
schemas: Add schemas for more CPU topology information in the caps XML
This patch adds RNG schemas for adding more information in the topology
output of the NUMA section in the capabilities XML.
The added elements are designed to provide more information about the
placement and topology of the processors in the system to management
applications.
A demonstration of supported XML added by this patch:
<capabilities>
<host>
<topology>
<cells num='3'>
<cell id='0'>
<cpus num='4'> <!-- this is node with Hyperthreading -->
<cpu id='0' socket_id='0' core_id='0' siblings='0-1'/>
<cpu id='1' socket_id='0' core_id='0' siblings='0-1'/>
<cpu id='2' socket_id='0' core_id='1' siblings='2-3'/>
<cpu id='3' socket_id='0' core_id='1' siblings='2-3'/>
</cpus>
</cell>
<cell id='1'>
<cpus num='4'> <!-- this is node with modules (Bulldozer) -->
<cpu id='4' socket_id='0' core_id='2' siblings='4-5'/>
<cpu id='5' socket_id='0' core_id='3' siblings='4-5'/>
<cpu id='6' socket_id='0' core_id='4' siblings='6-7'/>
<cpu id='7' socket_id='0' core_id='5' siblings='6-7'/>
</cpus>
</cell>
<cell id='2'>
<cpus num='4'> <!-- this is a normal multi-core node -->
<cpu id='8' socket_id='1' core_id='0' siblings='8'/>
<cpu id='9' socket_id='1' core_id='1' siblings='9'/>
<cpu id='10' socket_id='1' core_id='2' siblings='10'/>
<cpu id='11' socket_id='1' core_id='3' siblings='11'/>
</cpus>
</cell>
</cells>
</topology>
</host>
</capabilities>
The socket_id field represents identification of the physical socket the
CPU is plugged in. This ID may not be identical to the physical socket
ID reported by the kernel.
The core_id identifies a core within a socket. Also this field may not
accurately represent physical ID's.
The core_id is guaranteed to be unique within a cell and a socket. There
may be duplicates between sockets. Only cores sharing core_id within one
cell and one socket can be considered as threads. Cores sharing core_id
within sparate cells are distinct cores.
The siblings field is a list of CPU id's the cpu id's the CPU is sibling
with - thus a thread. The list is in the cpuset format.
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