Stop Using “Real Time” Wrong
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Stop Using “Real Time” Wrong
1–10 of 23 posts
Re: Stop Using “Real Time” Wrong
#2The author claims real time has nothing to do with response time. While response time is precisely the point of real time. If a system guarantees the response time of some action is always below a threshold it's real time.
Re: Stop Using “Real Time” Wrong
#3The author claims real time has nothing to do with response time. While response time is precisely the point of real time. If a system guarantees the response time of some action is always below a threshold it's real time.
> If a system guarantees the response time of some action is always below a threshold it's real time.
That's pretty much what the author said:
> Real time doesn’t mean instantaneous, or even as fast as possible, it means there’s a clear deadline in the system that the process must complete by a certain amount of time. That deadline need not be milliseconds. It can be weeks. In hard real time systems the system is verified in such a fashion that we can assume it’s impossible for the deadline to be violated. If the deadline is slipped the system is broken.
From what I got, the author's complaint is that most people who talk about "real-time" don't actually define, let alone guarantee such a threshold. Without it, the term becomes a marketing buzzword.
The actual definition is even more strict, implying a system cannot break the deadline because the time cost is completely deterministic and when you start a process you can already know the exact point in time the process finishes. That would rule out using any operations that have a nondeterministic time cost, such as dynamic scheduling or network requests.
Re: Stop Using “Real Time” Wrong
#4I always thought real time is "not interrupted".
Re: Stop Using “Real Time” Wrong
#5Real-Time. Consistency. High-Availability. Concurrency. Words with too many different meanings are not sufficient for describing softwares. I treat those words as marketing terms.
Re: Stop Using “Real Time” Wrong
#6I've seen real time to mean "must finish in x seconds or else fail" which means technically after x seconds you may simply exit the process, and the definition has been fulfilled.
Re: Stop Using “Real Time” Wrong
#7The author claims real time has nothing to do with response time. While response time is precisely the point of real time. If a system guarantees the response time of some action is always below a threshold it's real time.
> If a system guarantees the response time of some action is always below a threshold it's real time. That's pretty much what the author said: > Real time doesn’t mean instantaneous, or even as fast as possible, it means there’s a clear deadline in the system that the process must complete by a certain amount of time. That deadline need not be milliseconds. It can be weeks. In hard real time systems the system is ver…
You can make network request in real time. You just need the right kind of network (like AFDX )
Re: Stop Using “Real Time” Wrong
#8The author claims real time has nothing to do with response time. While response time is precisely the point of real time. If a system guarantees the response time of some action is always below a threshold it's real time.
> If a system guarantees the response time of some action is always below a threshold it's real time. That's pretty much what the author said: > Real time doesn’t mean instantaneous, or even as fast as possible, it means there’s a clear deadline in the system that the process must complete by a certain amount of time. That deadline need not be milliseconds. It can be weeks. In hard real time systems the system is ver…
I often heard the distinction between "soft" real time and "hard" real time, where "soft" essentially means "can be expected to meet the deadline" and "hard" means the real thing, i.e. "is guaranteed to meet the deadline".
Re: Stop Using “Real Time” Wrong
#9I always thought real time is "not interrupted".
Yeah, I would say "cannot be preempted", so the author is right it can be understood to mean different things. I've never heard of this "has a deadline that can't be broken definition" before.
Re: Stop Using “Real Time” Wrong
#10I always thought real time is "not interrupted".
I think of it as synchronous and continues.