[PD] PD and latency on kernel 2.6.14.2-lsm

Christian Klippel ck at mamalala.de
Sat Nov 19 11:28:34 CET 2005


Am Samstag 19 November 2005 09:09 schrieb IOhannes m zmölnig:
[...snip...]
>
> no, the most important thing is, that they have a maximum latency aka
> "deadline" that must not be exceeded.
>
> > also, see here: http://en.wikipedia.org/wiki/Real-time_computing
>
> quoting this artile:
>
> "It is important to note that hard versus soft real-time does not
> necessarily relate to the length of time available. A machine may
> overheat if a processor does not turn on cooling within 15 minutes (hard
> real-time). On the other hand, a network interface card may lose
> buffered data if it is not read within a fraction of a second, but the
> data can be resent over the network if needed, without affecting a
> critical operation, perhaps without a delay noticeable to the user."
>

ah, ok. then i was wrong.
my understanding of realtime vs. hard realtime was always that realtime is 
like: to process an hour of audio, it needs an hour. but its uncertain when 
it is done. whereas under hard realtime i understood that things get 
processed as fast as possible within a guaranteed time. i was not thinking 
about when the result of that is sent, that can be done later. but the 
processing/capture (aquisition) of the data is "immediate". and latency for 
me means the time difference between the incomming event and the resulting 
outgoing event. so yes, a hard realtime thing can have a long latency....

but we never stop to learn, me included ;)

>
>
> but then i am no real time specialist.
>

me neither ... ;)

> mfg.adr
> IOhannes
>

greetings,

chris





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