[Kimchi-devel] RFC: smt support

[Aline Manera]

Christy,

I added SMT support to 1.3 sprint 1.
Let me know if it works for you, otherwise I move it to sprint 2

https://github.com/kimchi-project/kimchi/wiki/Todo-1.3

On 07/03/2014 10:26 AM, Aline Manera wrote:
>
>
> On 07/02/2014 11:30 AM, Christy Perez wrote:
>>
>>
>>
>> On Wed, 2014-07-02 at 09:50 -0300, Paulo Ricardo Paz Vital wrote:
>>>>
>>>> On 07/01/2014 11:32 PM, Aline Manera wrote:
>>>>>
>>>>> On 06/26/2014 07:27 PM, Christy Perez wrote:
>>>>>> Quick poll for adding support for
>>>>>> <cpu>
>>>>>>       <topology sockets='1' cores='2' threads='1'/>
>>>>>> </cpu>
>>>>>>
>>>>>> I know it would be nice to let users add it on a per-vm basis, but
>>>>>> maybe
>>>>>> it might be something that we'd rather just leave in the template
>>>>>> only.
>>>>>> Having it in the template only seems simpler when thinking about UI
>>>>>> design, imo, but I'd love to hear what everyone else thinks.
>>>>>
>>>>> According to the reference
>>>>> https://www.ibm.com/developerworks/community/blogs/fe313521-2e95-46f2-817d-44a4f27eba32/entry/enabling_smt_on_powerkvm_guests?lang=en
>>>>>
>>>>>
>>>>> There are some restrictions to configure SMT what can not be intuitive
>>>>> for a Kimchi user.
>>>>>
>>>>> So I like the idea to keep it only on templates (at least for while)
>>>>> and see how Kimchi users react on that.
>>>>> We will need to properly add a logic to get the best pairs of
>>>>> cores/threads according to the vcpus number.
>>>>>
>>>>> In my mind, we should only add a check box on Template edit: "Enable
>>>>> SMT" if checked Kimchi knows what it needs to do when creating a VM
>>>>>
>> I'm fine with only on template edit. In the future, though, hopefully
>> we'll be adding maybe an "Advanced" sub-panel when creating templates
>> that lets users do things like this?
>>>
>
> Agree.
> This kind of info may be too complex for a Kimchi user
> I'd say to start only with the check box and in future (after getting
> feedbacks) add more details in the "Advanced" panel
>
>>> I think we can do something better! In addition to the check box, we can
>>> provide a combo box with the available choices for SMT. These values are
>>> static defined as SMT=1, SMT=2, SMT=4, or SMT=8.
>>>
>>> So, when the user select the SMT check box, the combo box make enable to
>>> user select one of these 4 options. Then, at the moment to write the
>>> XML, Kimchi backend do math to create the topology entry based on the
>>> SMT value and the number of processors defined.
>>>
>>> For example, if user sets a template to have 8 processors and SMT=4, the
>>> backend must create following entry on the XML file:
>>>
>> What if they set 7 processors? We could disable the SMT checkboxes if
>> their CPU # wasn't a multiple of anything. So we'll probably have to
>> come up with very good help/hint text for this.
>>
>> Or, if they select SMT, the CPU box becomes un-editable, and then
>> selecting one of the SMT options, the CPU count (in the un-editable
>> field) is updated so that they can understand what VCPU count they'll
>> end up before they click OK.
>>
>>> <vcpu>8</vcpu>
>>> <cpu>
>>> <topology sockets='1' cores='2' threads='4'/>
>>> </cpu>
>>>
>>> That's my 3 cents.
>>> Thanks and best regards,
>>> Paulo Vital
>>>
>>
>>
>
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