[Info-vax] clock problems with OpenVMS x86 on VirtualBox

[Johnny Billquist]

On 2023-05-13 02:16, Arne Vajhøj wrote:
> On 5/12/2023 1:30 PM, Simon Clubley wrote:
>> On 2023-05-12, Dave Froble <davef at tsoft-inc.com> wrote:
>>> On 5/12/2023 8:14 AM, Simon Clubley wrote:
>>>> That's going to make for some "interesting" real-time program 
>>>> behaviour... :-)
>>>
>>> Do you think any serious real time programmer will run a real time 
>>> task inside a
>>> VM?  I'm not a real time programmer, and I'd still not do that.
>>
>> As well as traditional real-time stuff (which I agree with you about 
>> BTW),
> 
> I would not want to do it on a type 2 hypervisor - there must be
> cases where what is happening on the host OS impact the performance
> of the guest OS.
> 
> But with a type 1 hypervisor and no over allocation of resources -
> would it be worse than running on bare metal?

For sure. You have no guarantee that you will get the CPU cycles when 
you need them. No matter what kind of hypervisor we're talking about, 
there is overhead in the host that can affect things way more than what 
might happen on bare metal.

   Johnny