4:53 a.m.
On 21/05/12 11:16, Yaniv Kaul wrote:
On 05/21/2012 11:08 AM, Doron Fediuck wrote:
> 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(a)redhat.com>
>>>>> To: dlaor(a)redhat.com
>>>>> Cc: engine-devel(a)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.
Safe is letting the user migrate. It may or may not succeed (I'd worry it may put a
host into Error state - I hope we've removed this state).
This is a pure
speculation. If I'm pinning a specific VM to a specific host, and its vCPUS into
specific pCPUs,
how can live migration be considered a safe thing? If I pinned to host, this is a
violation of my request. Now, let's say
I didn't pin to host, but I ask for specific vCPUS pinning into specific pCPUs. For
now, there's no guarantee the destination
host will have a relevant CPU capacity (maybe even topology), so CPU pinning may not work,
which is also a violation of
my request. Is live migration really the safe thing to do here??? Why not alert me so I
could manually migrate to where I think
is better?
Having that said, I'm reminding you the somewhere earlier in this thread I wrote
we'll make the constraint of cpu pinning
allowed only on pinned-to-host VMs configurable, so people who wish to walk on wild side,
can give it a go.
Sorry is when you wish you had done so initially. ;-)
In this
case, I disagree as this is configurable.
Y.
>
>>>>>>> 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(a)redhat.com>
>>>>>>>>> To: engine-devel(a)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!"
>>>>>>>>> _______________________________________________
>>>>>>>>> Engine-devel mailing list
>>>>>>>>> Engine-devel(a)ovirt.org
>>>>>>>>> http://lists.ovirt.org/mailman/listinfo/engine-devel
>>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> Engine-devel mailing list
>>>>>>>> Engine-devel(a)ovirt.org
>>>>>>>> http://lists.ovirt.org/mailman/listinfo/engine-devel
>>>>>>>
>>>>>
>>>>> --
>>>>>
>>>>> /d
>>>>>
>>>>> Never say "OOPS!" always say "Ah, Interesting!"
>>>>> _______________________________________________
>>>>> Engine-devel mailing list
>>>>> Engine-devel(a)ovirt.org
>>>>> http://lists.ovirt.org/mailman/listinfo/engine-devel
>>>>>
>>>
>
--
/d
Why doesn't DOS ever say "EXCELLENT command or filename!"