Messages in this thread | | | Date | Thu, 22 Jul 1999 17:59:43 -0400 | From | Raul Miller <> | Subject | Re: real-time threaded IO with low latency (audio) |
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David Olofson <audiality@swipnet.se> wrote: > I think this whole discussion is beginning to get confused by different > definitions of "real time". (Not the first time...) Basically, there are > two kinds: > > 1) Soft real time > * Typically ms precision timing. > * No guaranteed deadlines. > > 2) Hard real time > * Usually significantly better than ms precision > * Guaranteed deadlines.
Maybe three kinds, see: http://hegel.ittc.ukans.edu/projects/kurt
<QUOTE> Some types of processing (eg. multimedia) do not fit well into the hard or soft real-time categories. The periodic requests made by multimedia applications are sensitive to variations in timing. As such, they are not well served by the loose guarantees provided by soft real-time systems. Hard real-time systems are often faced with providing guarantees at the expense of providing services. Thus, while they can meet the timing requirements of a multimedia application, many times they cannot meet it's other service requirements. For example, real-time processes running under RTLinux have no access to any of the Linux services.
A purely binary distinction between hard and soft real-time is clearly not acceptable for all applications. Many applications have requirements spanning a continuum between the two. ... </QUOTE>
[With supposedly a demo where a modified xanim performs better on a loaded system.]
-- Raul
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