Messages in this thread | | | Date | Thu, 22 Jul 1999 01:13:53 +0200 | From | Ove Ewerlid <> | Subject | Re: [OFFTOPIC] Is Linux a Realtime-os? |
| |
John Alvord wrote: > > Rreal-time OS means that you can schedule tasks and they will be performed > at the time requested with a very small margin for error. That is not > Linux. There a Linux patch (largeish) called RTLiux which adds that > facility. Of course the tasks are not normal linux processes...
A real time OS is an OS that allows you to use the hardware to the limits! The road to the limits often involves modification of the OS it self (to fit custom needs). If you do not have the source code - this road is blocked. By this definition Linux is one of the few properly field tested RT OS's around. (do not take this too literally :-)
A custom "need" may be to deal with signal processing where algorithms do not tolerate 1-2 usec of interruptions*. E.g., cache flushes, bus contention and page table invalidation's are your enemies here - you can't deal with this efficiently and you have to resort to such exotic and expensive stuff as "real" signal processors in environments where you really should use that nice dual PIII with KNI as it is standing there anyway for various reasons.
In some areas, Linux with minor kernel hacks and creative user level hacks, fits the RT OS "glove" sooo nicely! It is simply amazingly funny to instrument a modern PC and push it to its hardware limits wrt RT using linux as the platform. Linux can accommodate "general purpose" and "heavily customized" under one hood very nicely indeed ...
Ove
* essentially means that you must lock _processors_ to specific tasks
-- Ove Ewerlid Ove.Ewerlid@syscon.uu.se or Ove.Ewerlid@signal.uu.se Phone: +46 70 666 23 63, Fax: +46 18 503 611, +46 18 555 096
- 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/
| |