Fwd: System partitioning question

Fwd: System partitioning question

[Mj Embd]

I have dual core ARM v7 ve system. I am trying to run xen on it.
>From a conceptual level if I have to run 2 os (VM) on xen, then in
effect there would 3 VMs running
2 guest os's for my purpose and the dom0.

How would 3 VM's run on two cores ?
Is it possible to affine cores in xen ?

==
Thanks

Re: Fwd: System partitioning question

[Gordan Bobic]

On 10/27/2013 09:17 AM, Mj Embd wrote:
> I have dual core ARM v7 ve system. I am trying to run xen on it.
>  From a conceptual level if I have to run 2 os (VM) on xen, then in
> effect there would 3 VMs running
> 2 guest os's for my purpose and the dom0.
>
> How would 3 VM's run on two cores ?
> Is it possible to affine cores in xen ?

If it is anything like x86, then you can overbook cores - Xen will 
manage what gets to run fairly. You can also specify how many cores you 
want dom0 to use and pin them, as well as specifying how many and which 
cores domU should run on.

Gordan

Re: Fwd: System partitioning question

[Mj Embd]

In my use case VM;s don't have any physical device, all are owned by dom0.
[keyboard, network] I am planning vnc to view the ubuntu's running in VM's
So I have to pin 1st core for dom0 and on second core my actual VM's
would  run ?
Would you think it would be a feasible solution in terms of latency ?


On Sun, Oct 27, 2013 at 3:03 PM, Gordan Bobic <gordan@bobich.net> wrote:
> On 10/27/2013 09:17 AM, Mj Embd wrote:
>>
>> I have dual core ARM v7 ve system. I am trying to run xen on it.
>>  From a conceptual level if I have to run 2 os (VM) on xen, then in
>> effect there would 3 VMs running
>> 2 guest os's for my purpose and the dom0.
>>
>> How would 3 VM's run on two cores ?
>> Is it possible to affine cores in xen ?
>
>
> If it is anything like x86, then you can overbook cores - Xen will manage
> what gets to run fairly. You can also specify how many cores you want dom0
> to use and pin them, as well as specifying how many and which cores domU
> should run on.
>
> Gordan
>



-- 
-mj

Re: Fwd: System partitioning question

[Gordan Bobic]

It doesn't matter - any VM can run on any CPU core and none require a 
dedicated CPU core. If your application is such that you are concerned 
about latency, the chances are that no virtualization solution is going 
to be good enough. Otherwise don't worry about it.

Gordan

On 10/27/2013 10:40 AM, Mj Embd wrote:
> In my use case VM;s don't have any physical device, all are owned by dom0.
> [keyboard, network] I am planning vnc to view the ubuntu's running in VM's
> So I have to pin 1st core for dom0 and on second core my actual VM's
> would  run ?
> Would you think it would be a feasible solution in terms of latency ?
>
>
> On Sun, Oct 27, 2013 at 3:03 PM, Gordan Bobic <gordan@bobich.net> wrote:
>> On 10/27/2013 09:17 AM, Mj Embd wrote:
>>>
>>> I have dual core ARM v7 ve system. I am trying to run xen on it.
>>>   From a conceptual level if I have to run 2 os (VM) on xen, then in
>>> effect there would 3 VMs running
>>> 2 guest os's for my purpose and the dom0.
>>>
>>> How would 3 VM's run on two cores ?
>>> Is it possible to affine cores in xen ?
>>
>>
>> If it is anything like x86, then you can overbook cores - Xen will manage
>> what gets to run fairly. You can also specify how many cores you want dom0
>> to use and pin them, as well as specifying how many and which cores domU
>> should run on.
>>
>> Gordan
>>
>
>
>

Re: Fwd: System partitioning question

[Ian Campbell]

On Sun, 2013-10-27 at 19:27 +0000, Gordan Bobic wrote:
> It doesn't matter - any VM can run on any CPU core and none require a 
> dedicated CPU core. If your application is such that you are concerned 
> about latency, the chances are that no virtualization solution is going 
> to be good enough. Otherwise don't worry about it.

Actually, given the presence of sEDF and the arinc653 schedulers (both
of which have RT properties) and the simplicity of the ARM interrupt
injection path I think Xen on ARM is probably not in too bad a shape for
a soft-ish RT system, at least as a starting point for
testing/measuring/improving etc. It depends on the specific requirements
of course.

Also remember that through cpupools you can split the physical CPUs into
RT and non-RT pools, each with their own scheduler and assign domains to
the appropriate pool.

Ian.