[Engine-devel] CPU Pinning @engine

[Dor Laor]

On 05/21/2012 10:58 AM, Doron Fediuck wrote:
> On 21/05/12 01:45, Andrew Cathrow wrote:
>>
>>
>> ----- Original Message -----
>>> From: "Doron Fediuck"<dfediuck at redhat.com>
>>> To: dlaor at redhat.com
>>> Cc: engine-devel at ovirt.org
>>> Sent: Sunday, May 20, 2012 5:49:08 PM
>>> Subject: Re: [Engine-devel] CPU Pinning @engine
>>>
>>> On 20/05/12 21:41, Dor Laor wrote:
>>>> On 05/17/2012 11:15 PM, Doron Fediuck wrote:
>>>>> On 17/05/12 20:28, Ayal Baron wrote:
>>>>>> "Live migration will not be supported for such VM's."
>>>>>>
>>>>>> Migration will work on homogeneous clusters so this should not be
>>>>>> enforced (not limited to VMs which are pinned to host) just give
>>>>>> a warning.
>>>>>>
>>>>> I agree, but if we wish to ping vCPUx to pCPUy in host a, we
>>>>> cannot ensure to have the same in host b,
>>>>> since it may have pCPUy too busy, so performance will degrade.
>>>>> Also, I hope you saw my general comment
>>>>
>>>> Performance may degrade on any migration to loaded host regardless
>>>> of pinning.
>>>>
>>>> There is not need to forbid migration. Instead, the SLA assurance
>>>> policy should verify the dedicated resources and match the target
>>>> w/ the guarantee and decide according to this.
>>>>
>>> Thanks for the input.
>>> We may start with migration blocked in a configurable manner, so
>>> people who wish migrate to work
>>> will simply set the relevant configuration key.
>>> As for looking for a matched CPU, will add it as p2.
>>
>> We shouldn't block migration
>> If a user wants to not migrate a cpu pinned VM then let them use the non-migratable flag in the UI.
>>
> We're not blocking migration, we're allowing pinning (for now) only for non-migrative VM's.
> For p2 we'll verify destination host has the relevant pinning capacity, which will allow
> pinning for migrative VM's as well.


IMHO the order should be the opposite - if the user likes to migrate a 
pinned VM, let him (you can pop some message if you like).

>
>>
>>>
>>>>> about starting with a humble solution and gradually improving. In
>>>>> this context (auto)numa can help us,
>>>>> so we better do numa than handle migration for basic mode, risking
>>>>> performance issues.
>>>>>
>>>>>>
>>>>>> ----- Original Message -----
>>>>>>> From: "Doron Fediuck"<dfediuck at redhat.com>
>>>>>>> To: engine-devel at ovirt.org
>>>>>>> Sent: Thursday, May 17, 2012 2:42:46 PM
>>>>>>> Subject: [Engine-devel] CPU Pinning @engine
>>>>>>>
>>>>>>> Hi All,
>>>>>>> Currently the VDSM has a CPU pinning hook.
>>>>>>> We'd like to add better support of it into the engine itself.
>>>>>>> Here's a design draft to cover it:
>>>>>>> http://www.ovirt.org/wiki/Features/Design/cpu-pinning
>>>>>>>
>>>>>>> Please review and comment if needed.
>>>>>>>
>>>>>>> Thanks!
>>>>>>> --
>>>>>>>
>>>>>>> /d
>>>>>>>
>>>>>>> Never say "OOPS!" always say "Ah, Interesting!"
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>>>>>>>
>>>>>> _______________________________________________
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>>>>>
>>>>>
>>>>
>>>
>>>
>>> --
>>>
>>> /d
>>>
>>> Never say "OOPS!" always say "Ah, Interesting!"
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>
>