[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

Re: [libvirt] virsh nodeinfo CPU detection questions



On 01/29/13 16:52, Scott Sullivan wrote:
I have a machine with four AMD Opteron(TM) 6272 processors:

http://www.amd.com/us/products/server/processors/6000-series-platform/6200/Pages/6200-series-processors.aspx#5


I use 'virsh nodeinfo' to determine the amount of physical CPUs, and CPU
cores. What values should I be looking at in the output of nodeinfo to
determine this? With 1.X libvirts the output values have changed from
0.9.4:

0.9.4:
[root host ~]# virsh nodeinfo
CPU model: x86_64
CPU(s): 64
CPU frequency: 2099 MHz
CPU socket(s): 4
Core(s) per socket: 8
Thread(s) per core: 2
NUMA cell(s): 1
Memory size: 24713980 kB
[root host28 ~]#

This version probably didn't detect the NUMA nodes correctly.


1.0.1:
[root host ~]# virsh nodeinfo
CPU model: x86_64
CPU(s): 64
CPU frequency: 2099 MHz
CPU socket(s): 1
Core(s) per socket: 8
Thread(s) per core: 2
NUMA cell(s): 4
Memory size: 24713980 KiB
[root host28 ~]#

As you can see, the CPU socket and NUMA cells values have changed in
these two versions, on the same machine. To get the physical CPU count,
is it safe to assume this?

Numa cell(s) X CPU Socket(s) == physical CPUs present

To detect the total physical count of processors (packages) you can't rely on this output.

You should refer to the recently added topology information in the capabilities XML (accessible through the command "virsh capabilities"). The NUMA topology section there holds information (specially "socket_id") that allow you to count the number of physical sockets on the machine.

Unfortunately, this output will be part of tomorrows release :)


However, I am not positive what formula I should use to determine the
CPU core count. On this processor, it has 16 cores. Would that mean I
can do this?

To determine the core count, you also need to refer to the information in capabilities. Unfortunately AMD processors (especially Bulldozer ones cannot be detected reliably with the code as it is now).


Core(s) per socket X Thread(s) per core: == CPU cores

Thanks in advance for clarifying.

--
libvir-list mailing list
libvir-list redhat com
https://www.redhat.com/mailman/listinfo/libvir-list


[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]