[Info-vax] The (now lost) future of Alpha.

[Arne Vajhøj]

On 8/6/2018 5:53 AM, Johnny Billquist wrote:
> On 2018-08-06 01:49, Arne Vajhøj wrote:
>> On 8/5/2018 7:28 PM, Johnny Billquist wrote:
>>> On 2018-08-04 00:28, Arne Vajhøj wrote:
>>>> C, C++ or Ada still provide easy HW access and
>>>> good real time characteristics, so they will
>>>> not go away.
>>>
>>> I might strongly disagree with this one. With C++, you have no idea 
>>> what happens when you do something in the language, making it 
>>> horrible for figuring out any sort of real time characteristics.
>>>
>>> Think classes, inheritance (even multiple inheritance), exceptions 
>>> and so on. You create an objects and you have no idea how much code 
>>> is executed, or how much memory is required. C++ is in general very 
>>> much depending on lots of memory, and a very dynamic memory 
>>> management model, which is horrible if we talk embedded and realtime 
>>> stuff.
>>>
>>> (But yes, I know C++ is being used by some people for those exact 
>>> environments anyway. I can just feel sorry for when, for some 
>>> surprising and unknown reason their devices do not work as expected.)
>>
>> Compared to languages that use GC then C++ is pretty good in this
>> regard.
>>
>> :-)
> 
> I would disagree. I'd say that is a dangerous thing to think or say, and 
> it sortof legitimizes the use of a bad language that have so much 
> uncontrolled things going on. Just because it don't use GC isn't enough 
> to make it predictable or good in this field. It isn't necessarily any 
> better just because it don't have one thing.

Some innocent looking C++ code may end up executing a lot of code.

But that should be in the 10 ns - 10 us range.

GC should be in the 5 ms - 250 ms range.

Several orders of magnitudes difference.

Arne