On Mon, 2007-05-21 at 16:28 +0200, Gilles Chanteperdrix wrote: > Igor Plyatov wrote: > > Is it possible to get 10us results in Xenomai or not? > > Running a task with a period of 10us is usually considered a bit out of > the scope of Xenomai. Nevertheles, there were some recent improvements > on Xenomai trunk that might make this possible.
There have been significant improvements on the Adeos/x86 side too, especially in SMP, now that we use PDAs. > It would be interesting > if you tested this with trunk and tell us whether it works. > Figures are really to be considered wrt the underlying hw Xenomai runs on: achieving < 10us latency is currently a no-brainer in user-space on recent x86_64 boxen, kernel space exhibits sub-2 us latencies there with a 500 ns calibration value for the timer, which is quite good (it's a 2 way dual core AMD Opteron 285). Results on high-end embedded PPC hw are quite good too IIRC. It's often a matter of memory sub-system, added to the presence of internal perturbations when it comes to the Intel world, like SMM etc. For instance, my oldish Dual PIII 750 Mhz delivers < 20 us in kernel space, which is as good as what I get with a P4-based 2.4Ghz uniprocessor system. Also, hw optimizations for the average use case (i.e. desktop) tend to kill real-time performances on Intel boxen. > Also note that in order to get ultra-low latencies, you have to properly > calibrate the nucleus latency (/proc/xenomai/latency). > > > May be better to use only ADEOS functions for my task, is it faster then > > RTDM? > > Adeos has no notion of a "task", so, you would have to implement your > task in an interrupt handler, and yes, you would get better performance > (see for example the difference between latency -t 2 and latency -t 1). > > > What is the state of RTAI nowadays, is it still a live? > > Well, you are not asking on the right mailing list. Try RTAI mailing list. > -- Philippe. _______________________________________________ Xenomai-help mailing list [email protected] https://mail.gna.org/listinfo/xenomai-help
