[Engine-devel] CPU Pinning @engine

[Doron Fediuck]

On 21/05/12 11:01, Dor Laor wrote:
> 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).
I'll check it with UI guys (AFAIK engine UI has no pop-ups).
Also, I prefer safe than sorry. So start with a safe working pinning for pinned-to-host VMs, and then push the envelope.

> 
>>
>>>
>>>>
>>>>>> 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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>>>>
>>
>>
> 


-- 

/d

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