[Info-vax] And another one bites the dust....

[Arne Vajhøj]

On 2/16/2022 10:44 AM, Johnny Billquist wrote:
> On 2022-02-15 18:21, Bill Gunshannon wrote:
>> On 2/15/22 11:00, Jan-Erik Söderholm wrote:
>>> Den 2022-02-15 kl. 16:46, skrev Bill Gunshannon:
>>>> On 2/15/22 10:16, Dan Cross wrote:
>>>>> In article <j71r42Fh9vsU1 at mid.individual.net>,
>>>>> Bill Gunshannon  <bill.gunshannon at gmail.com> wrote:
>>>>>> Maybe, but the push seems to be for virtualization and I saw a number
>>>>>> of OpenVMS job announcements that seemed to be production floor systems
>>>>>> which probably can't virtualized.
>>>>>
>>>>> Why not?  There are reasons to virtualize systems on-prem.
>>>>
>>>> I guess it depends on how you actually communicate with the
>>>> devices on the floor.  When I think of production floor systems
>>>> I think of cables between running machines and computers.
>>>> Probably my PDP-11 past seeping through.
>>>
>>> Our VMS production support system only talks over the network.
>>> Could just as well be in a VM as on the current Alpha.
>>>
>>
>> I thought of that afterwards. I guess a  lot of it today is PLC's
>> talking to the bigger iron over the network.  But that just leaves
>> me wondering how one does realtime.
> 
> Throw lots of hardware resources as the problem, and pray. That's what I 
> usually see... Usually aided by the fact that a lot of situations isn't 
> hard realtime.

I would expect the real time characteristics to depend on the OS
and the execution environment (read: if you want good real time
characteristics then avoid GC) not virtualization vs non-virtualization.

Assuming a type 1 (bare metal) hypervisor and no over-commitment of
resources (aka number CPU's in VM's <= physical CPU's present), then
I don't see how virtualization should be a problem.

Arne