[SystemSafety] What do we know about software reliability?
Derek M Jones
derek at knosof.co.uk
Wed Sep 16 03:05:06 CEST 2020
Hugues
> if A then
> do_nothing
> else
> fail --potentially hurt and kill people
> end if
>
> end
>
> The specification of the software is to do nothing;
> NB: I'm not asking if it is the best implementation, whatever the criteria are, but just : "is it reliable?"
The "if A then"
could be unreliable, in that a cosmic ray could flip its value.
There are research compilers that reduce the likelihood of a
cosmic ray altering the behavior of a program:
http://shape-of-code.coding-guidelines.com/2011/11/07/compiling-to-reduce-the-impact-of-soft-errors-on-program-output/
Circa 2011, 1-bit of a 4GB RAM had its value flipped roughly every 33
hours as a result of a cosmic ray hitting the upper atmosphere.
> regards,
>
> Hugues
>
>
> ----- Mail original -----
>> De: "Peter Bernard Ladkin" <ladkin at causalis.com>
>> À: systemsafety at lists.techfak.uni-bielefeld.de
>> Envoyé: Mardi 15 Septembre 2020 19:58:45
>> Objet: Re: [SystemSafety] What do we know about software reliability?
>>
>> Bev and I and Dewi have a colleague who poses the following question.
>>
>> "We have clients who have installed hundreds of [examples of our kit]
>> over the last ten years, and
>> have never seen any failure. They want to use it in further systems
>> that they build. What arguments
>> do we/they need to provide in order validly to justify such further
>> use?"
>>
>> So, what is the answer to that question?
>>
>> PBL
>>
>> Prof. Peter Bernard Ladkin, Bielefeld, Germany
>> Styelfy Bleibgsnd
>> Tel+msg +49 (0)521 880 7319 www.rvs-bi.de
>>
>>
>>
>>
>>
>>
>> _______________________________________________
>> The System Safety Mailing List
>> systemsafety at TechFak.Uni-Bielefeld.DE
>> Manage your subscription:
>> https://lists.techfak.uni-bielefeld.de/mailman/listinfo/systemsafety
> _______________________________________________
> The System Safety Mailing List
> systemsafety at TechFak.Uni-Bielefeld.DE
> Manage your subscription: https://lists.techfak.uni-bielefeld.de/mailman/listinfo/systemsafety
>
--
Derek M. Jones Evidence-based software engineering
tel: +44 (0)1252 520667 blog:shape-of-code.coding-guidelines.com
More information about the systemsafety
mailing list