Am 2017-01-29 16:33, schrieb Alex Williamson:
On Sat, 28 Jan 2017 12:58:41 +0100
Thomas Lindroth <thomas.lindr...@gmail.com> wrote:
On 01/27/2017 04:52 PM, Alex Williamson wrote:
> vcpupin actually looks a little off though, just like on the host, the
> VM is going to enumerate cores then threads
Are you sure about that? Perhaps there is some numa trick I don't
understand but it looks like the guest is a regular 6 cores
with HT (<topology sockets='1' cores='6' threads='2'/>) and
for me setups like that results in a layouts like this in the
guest (qemu-2.8.0):
cat /proc/cpuinfo |grep "core id"
core id : 0
core id : 0
core id : 1
core id : 1
core id : 2
core id : 2
The ordering in the guest is threads then cores but for the
host it's the other way around
cat /proc/cpuinfo |grep "core id"
core id : 0
core id : 1
core id : 2
core id : 3
core id : 0
core id : 1
core id : 2
core id : 3
Cores then threads. So to get a 1:1 match I have to use
pinning like this which is similar to that numa setup.
<vcpupin vcpu='0' cpuset='1'/>
<vcpupin vcpu='1' cpuset='5'/>
<vcpupin vcpu='2' cpuset='2'/>
<vcpupin vcpu='3' cpuset='6'/>
<vcpupin vcpu='4' cpuset='3'/>
<vcpupin vcpu='5' cpuset='7'/>
<topology sockets='1' cores='3' threads='2'/>
Oh wow, maybe I'm completely off. I hadn't noticed the core-id
ordering in the VM, but indeed on my system the guest shows:
core id : 0
core id : 0
core id : 1
core id : 1
core id : 2
core id : 2
core id : 3
core id : 3
Any physical system I've seen has the ordering you show above,
enumerating cores then threads. Sorry Jan, maybe the way you had it
originally was optimal. Thanks,
Alex
Ah, good to know! I will change my config back to the original one.
I was curious how I could get this information on a Windows system.
After some googling I found coreinfo [1], which reports this:
Logical to Physical Processor Map:
**---------- Physical Processor 0 (Hyperthreaded)
--**-------- Physical Processor 1 (Hyperthreaded)
----**------ Physical Processor 2 (Hyperthreaded)
------**---- Physical Processor 3 (Hyperthreaded)
--------**-- Physical Processor 4 (Hyperthreaded)
----------** Physical Processor 5 (Hyperthreaded)
But I'm still having my memory allocation problem: Can someone confirm
that the numatune option actually works? I'm interested in the
Kernel/Qemu/Libvirt version.
Jan
[1] https://technet.microsoft.com/en-us/sysinternals/cc835722.aspx
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