[libvirt] [PATCH 2/3] conf: Initialize the pinning policy for vcpus

[Osier Yang]

On 2012年10月10日 23:34, Martin Kletzander wrote:
> On 10/10/2012 01:14 PM, Osier Yang wrote:
>> There are two branches to specifiy the pinning policy for vcpus.
>>
>> 1) def->cpuset:
>>
>>     <vcpu cpuset='0-10,^6'>6</vcpu>
>>
>> 2) def->cputune.vcpupins:
>>
>>     <cputune>
>>       <vcpupin vcpuid='1' cpuset='0-5'/>
>>     </cputune>
>>
>> def->cputune.vcpupins only maintains the pinning policy only for
>> vcpus have<vcpupin>  specified explictly, this works fine before
>
> s/explictly/explicitely/, but...
>
>> cgroup is widely used for domain. But since now cgroup uses
>> def->cputune.vcpupins to setup the cgroups for each vcpus thread,
>> it means the vcpus which doesn't has<vcpupin>  specified will
>> be ignored for cgroup setting.
>>
>
> ... anyway, I didn't quite get that for the first time. However IIUC for
> the second time I think it's enough to mention that in case there are
> both cpuset and cputune with vcpupin, we don't enforce the cpuset for
> vcpus not specified in the cputune.
>
> OK, maybe mine version is not that readable either :-)
>
>> To fix the problem, the patch initialize vcpupin for each vcpu
>> which doesn't has<vcpupin>  specified as def->cpuset.
>>
>> Problem example without this patch:
>>
>> 1. % virsh start dom
>> Domain dom started
>>
>>
>> 2. % virsh dumpxml dom
>> <vcpu placement='static' cpuset='3'>4</vcpu>
>>
>> 3. % virsh vcpuinfo dom
>> VCPU: 0
>> CPU: 0
>> State: running
>> CPU time: 8.3s
>> CPU Affinity: yyyyyyyy
>>
>> VCPU: 1
>> CPU: 4
>> State: running
>> CPU time: 2.4s
>> CPU Affinity: yyyyyyyy
>>
>> VCPU: 2
>> CPU: 0
>> State: running
>> CPU time: 4.1s
>> CPU Affinity: yyyyyyyy
>>
>> VCPU: 3
>> CPU: 1
>> State: running
>> CPU time: 2.8s
>> CPU Affinity: yyyyyyyy
>>
>

/me knocking the head.....

Never mind to ignore this set now, I made a pricinple mistake,
the "cpuset" for "<vcpupin>" should not inherit "cpuset" of "<vcpu>".
They are for different purposes. "cpuset" of "<vcpu>" is to set
the pinning policy for domain process, while "cpuset" of "<vcpupin>"
is to set the pinning policy for vcpu thread.

BTW, the new <emlatorpin> is conflicts with "cpuset" of "<vcpu>",
we just have too much XML tags for NUMA tuning. /sigh. But let's
settle down it later.

Regards,
Osier