On 04/07/2012 07:33 AM, Anisha Kaul wrote: > Greetings, > > From here: http://www.xenomai.org/index.php/Xenomai:Roadmap#Xenomai_3_FAQ > > Quote: >> the target hardware platform has limited horsepower, and/or you want the >> real-time job to put the smallest possible overhead on your system. This is >> where dual kernels are usually better than a native preemption system. > > > Preempt_rt does preempt the whole Linux. In what way does preempting > Linux put load on the system?
I think you are misunderstanding what preempt_rt is, preempt_rt does not preempt linux, preempt_rt is simply linux modified, when a linux kernel patched with preempt_rt runs, nothing else than linux runs, so nothing preempts the whole linux. This is achieved by means which have a global overhead on the whole system. The exact means are described on the rt wiki FAQ: https://rt.wiki.kernel.org/articles/f/r/e/Frequently_Asked_Questions_7407.html Note the answer to FAQ 3, which explains that improving latencies is a trade off, and means degrading the average performances of the system. That is the overhead we are talking about. -- Gilles. _______________________________________________ Xenomai-help mailing list Xenomai-help@gna.org https://mail.gna.org/listinfo/xenomai-help
