Re: [RFC PATCH 0/7] sched: cpufreq: Remove magic margins

Daniel Bristot de Oliveira
2023-09-08T12:52:48Z

On 9/7/23 15:45, Lukasz Luba wrote:
>>>> RT literatur mostly methinks. Replacing WCET with a statistical model of
>>>> sorts is not uncommon, the argument goes that not everybody will have
>>>> their worst case at the same time and lows and highs can commonly cancel
>>>> out and this way we can cram a little more on the system.
>>>>
>>>> Typically this is proposed in the context of soft-realtime systems.
>>>
>>> Thanks Peter, I will dive into some books...
>>
>> I would look at academic papers, not sure any of that ever made it to
>> books, Daniel would know I suppose.
>
> Good hint, thanks!

The key-words that came to my mind are:

- mk-firm, where you accept m tasks will make their deadline
every k execution - like, because you run too long.
- mixed criticality with pWCET (probabilistic execution time) or
average execution time + an sporadic tail execution time for
the low criticality part.

mk-firm smells like 2005's.. mixed criticality as 2015's..present.

You will probably find more papers than books. Read the papers
as a source for inspiration... not necessarily as a definitive
solution. They generally proposed too restrictive task models.

-- Daniel