On 04/27/2017 06:27 PM, Philippe Gerum wrote: > 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. >
Btw, there is a validated port of kernel 4.1 to the RPI Zero available from git://git.xenomai.org/ipipe.git, vendors/beaglebone/ipipe-4.1. -- Philippe. _______________________________________________ Xenomai mailing list [email protected] https://xenomai.org/mailman/listinfo/xenomai
