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Long story short, i want my VM have dedicated CPU and it has to be
1-0-1 map. because i am running VoIP application and i need CPU
dedicate to guest VM.  what i should do?

On Tue, Dec 15, 2015 at 12:34 PM, Arne Wiebalck <Arne.Wiebalck at cern.ch> wrote:
> Thanks for clarifying the terminology, Chris, that’s helpful!
>
> My two points about performance were:
> - without overcommit, an instance confined in a NUMA node does not profit from 1-to-1 pinning (at least from what we saw);
> - an instance spanning multiple NUMA nodes needs to be aware of the topology (and our instances fulfil your condition for this).
>
> Cheers,
>  Arne
>
>
>> On 15 Dec 2015, at 18:19, Chris Friesen <chris.friesen at windriver.com> wrote:
>>
>> If you specify "vcpu_pin_set=2,3,6,7" in /etc/nova/nova.conf then nova will limit the VMs to run on that subset of host CPUs.  This involves pinning from libvirt, but isn't really considered a "dedicated" instance in nova.
>>
>> By default, instances that can run on all of the allowed host CPUs are considered "non-dedicated", "shared", or "floating" because the vCPUs are not mapped one-to-one with a single host CPU.  For these instances the CPU overcommit value determines how many vCPUs can run on a single host CPU.
>>
>> If an instance specifies a cpu_policy of "dedicated", then each vCPU is mapped one-to-one with a single host CPU.  This is known as a "pinned" or "dedicated" instance.
>>
>> The performance differences between the two come into play when there is contention.  By default a non-dedicated vCPU can have 16x overcommit, so there can be 16 vCPUs trying to run on a single host CPU.  In contrast, a dedicated vCPU gets a whole host CPU all to itself.
>>
>> As for the guest being aware of the underlying NUMA topology, this isn't possible when the number of vCPUs in the instance isn't a multiple of the number of hyperthreads in a host core.  The problem is that qemu doesn't have a way to specify cores with varying numbers of threads.
>>
>> Chris
>>
>> On 12/15/2015 10:50 AM, Arne Wiebalck wrote:
>>> What was configured was pinning to a set and that is reflected, no? Or is that not referred to as “pinning”?
>>> Anyway, for performance we didn’t see a difference between 1:1 pinning and confining (?) the vCPUs to a
>>> a set as long as the instance is aware of the underlying NUMA topology.
>>>
>>> Cheers,
>>>  Arne
>>>
>>>
>>>> On 15 Dec 2015, at 17:11, Chris Friesen <chris.friesen at windriver.com> wrote:
>>>>
>>>> Actually no, I don't think that's right.  When pinning is enabled each vCPU will be affined to a single host CPU.  What is showing below is what I would expect if the instance was using non-dedicated CPUs.
>>>>
>>>> To the original poster, you should be using
>>>>
>>>> 'hw:cpu_policy': 'dedicated'
>>>>
>>>> in your flavor extra-specs to enable CPU pinning.  And you should enable the NUMATopologyFilter scheduler filter.
>>>>
>>>> Chris
>>>>
>>>>
>>>>
>>>> On 12/15/2015 09:23 AM, Arne Wiebalck wrote:
>>>>> The pinning seems to have done what you asked for, but you probably
>>>>> want to confine your vCPUs to NUMA nodes.
>>>>>
>>>>> Cheers,
>>>>>  Arne
>>>>>
>>>>>
>>>>>> On 15 Dec 2015, at 16:12, Satish Patel <satish.txt at gmail.com> wrote:
>>>>>>
>>>>>> Sorry forgot to reply all :)
>>>>>>
>>>>>> This is what i am getting
>>>>>>
>>>>>> [root at compute-1 ~]# virsh vcpupin instance-00000043
>>>>>> VCPU: CPU Affinity
>>>>>> ----------------------------------
>>>>>>   0: 2-3,6-7
>>>>>>   1: 2-3,6-7
>>>>>>
>>>>>>
>>>>>> Following numa info
>>>>>>
>>>>>> [root at compute-1 ~]# numactl --hardware
>>>>>> available: 2 nodes (0-1)
>>>>>> node 0 cpus: 0 3 5 6
>>>>>> node 0 size: 2047 MB
>>>>>> node 0 free: 270 MB
>>>>>> node 1 cpus: 1 2 4 7
>>>>>> node 1 size: 2038 MB
>>>>>> node 1 free: 329 MB
>>>>>> node distances:
>>>>>> node   0   1
>>>>>>  0:  10  20
>>>>>>  1:  20  10
>>>>>>
>>>>>> On Tue, Dec 15, 2015 at 8:36 AM, Arne Wiebalck <Arne.Wiebalck at cern.ch> wrote:
>>>>>>> The pinning we set up goes indeed into the <cputune> block:
>>>>>>>
>>>>>>> —>
>>>>>>> <vcpu placement='static'>32</vcpu>
>>>>>>>  <cputune>
>>>>>>>    <shares>32768</shares>
>>>>>>>    <vcpupin vcpu='0' cpuset='0-7,16-23'/>
>>>>>>>    <vcpupin vcpu='1' cpuset='0-7,16-23'/>
>>>>>>>    …
>>>>>>> <—
>>>>>>>
>>>>>>> What does “virsh vcpupin <domain>” give for your instance?
>>>>>>>
>>>>>>> Cheers,
>>>>>>> Arne
>>>>>>>
>>>>>>>
>>>>>>>> On 15 Dec 2015, at 13:02, Satish Patel <satish.txt at gmail.com> wrote:
>>>>>>>>
>>>>>>>> I am running JUNO version with qemu-kvm-ev-2.1.2-23.el7_1.9.1.x86_64
>>>>>>>> on CentOS7.1
>>>>>>>>
>>>>>>>> I am trying to configure CPU pinning because my application is cpu
>>>>>>>> hungry. this is what i did.
>>>>>>>>
>>>>>>>> in /etc/nova/nova.conf
>>>>>>>>
>>>>>>>> vcpu_pin_set=2,3,6,7
>>>>>>>>
>>>>>>>>
>>>>>>>> I have created aggregated host with pinning=true and created flavor
>>>>>>>> with pinning, after that when i start VM on Host following this i can
>>>>>>>> see in guest
>>>>>>>>
>>>>>>>> ...
>>>>>>>> ...
>>>>>>>> <vcpu placement='static' cpuset='2-3,6-7'>2</vcpu>
>>>>>>>> ...
>>>>>>>> ...
>>>>>>>>
>>>>>>>> But i am not seeing any <cputune> info.
>>>>>>>>
>>>>>>>> Just want to make sure does my pinning working correctly or something
>>>>>>>> is wrong. How do i verify my pinning config is correct?
>>>>>>>>
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>>>>>>>
>>>>>>> --
>>>>>>> Arne Wiebalck
>>>>>>> CERN IT
>>>>>>>
>>>>>
>>>>> --
>>>>> Arne Wiebalck
>>>>> CERN IT
>>>>>
>>>>> _______________________________________________
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>>>>>
>>>>
>>>>
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>>>
>>> --
>>> Arne Wiebalck
>>> CERN IT
>>>
>>
>
> --
> Arne Wiebalck
> CERN IT
>
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