Hi,
   We recently ported our application to Linux(4.19.25)/Xenomai from RTOS.
We have time critical routines in our application. This routine is run in
Xenomai user threads with the highest priority. We run each routine on a
core(Affinity to the CPU is set up for the threads). We have a RTDM driver
which triggers these routines. We are seeing a maximum/mean latency of
100/25 microseconds respectively from the interrupt assertion to running
the real time routine in Xenomai user thread. Our platform is i.MX6 (ARM
Cortex-A9 Quad Core) running at 996 MHz. Is that latency reasonable for
Xemonai? We are also seeing something strange. The execution time of the
real time routines is twice as long as it took on the RTOS. We are not
making any calls to the Linux inside these real time routines. The
execution time of the routine is 500 microseconds in Xenomai thread. But on
an RTOS running this routine in an interrupt context takes only 250
microseconds. What is the reason for this higher execution time? Is the
xenomai thread getting preempted by some timer irq? Is there a way to avoid
this preemption?

Rajesh

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