>> Does "hard" mean human life is involved? What about large sums of
>> money? (and define "large" too if that is the case)
>
> A hard real time constraint is one that must be met or the
> program fails. It is hard as in solid and inflexible.
Oh, like user-space Win-printer software. If the deadline is
not met, the printer will eject the paper with garbage on it.
> A soft realtime constraint is one that the operating environment
> must make a best effort to meet.
>
>> You could lose money at an exponential rate, 2**n $ for every
>> microsecond past your deadline.
>
> A soft real time constraint, in spite of the high motivation.
Ouch. By your definition, the distinction is worthless. I'd much
rather have a Win-printer fail than lose money at an exponential rate.
Well, maybe not quite. When the hard real-time process is delayed
too long, the kernel can just send it signal 9. That's not enough
of a distinction to care about.
Better questions might be:
1. What is the desired response time?
2. What level of reliability will you pay for?
That could be interpreted as "Are you willing to buy a commercial
system or hack the Linux kernel to improve the response time?".
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/