On 04/27/2017 06:09 PM, Adam Vaughan wrote: > Hi Gerber, > > I haven't tried Xenomai on the RPi in a few years (I've been working > on BeagleBone Xenomai lately), but I have experimented with Xenomai > 2.6 patches on the RPi 1 in the configuration you describe. > > There's more detail in section 7.5 in my dissertation [1], but I > strongly suggest checking that the USB driver isn't affecting your > overall system latency numbers under load. Under heavy USB Ethernet > usage with the FIQ turned off I measured system stalls of up to 15 > milliseconds under Xenomai with an oscilloscope. > > The only fix I had for this was to use PREEMPT_RT to lower the USB > driver thread priority. At the time, I couldn't get PREEMPT_RT > patches to cleanly apply to the available Xenomai kernel patches, so I > ended up just using PREEMPT_RT exclusively. This patch situation is > likely different these days.
I don't think any regular driver thread priority could interfere with the dual kernel operating in primary/real-time mode, that is actually a selling point of the pipelined IRQ architecture which decouples the regular kernel logic from the real-time core. Using the I-pipe tracer combined with the -f option from the latency test may give some hints about the issue. -- Philippe. _______________________________________________ Xenomai mailing list [email protected] https://xenomai.org/mailman/listinfo/xenomai
