I build the OpenStLinux from the ST Yocto project and added the Preempt_RT patch to make the kernel "real-time". ( uname -a correctly report PREEMP_RT kernel).
After this, I am checking real-time capabilities with the rt-tests utilities.
When calling
root@stm32mp1-rt:/boot# cyclictest --mlockall -t -a --priority=99 --interval=200 --distance=0 -l 0
WARN: stat /dev/cpu_dma_latency failed: No such file or directory
policy: fifo: loadavg: 4.69 2.97 2.01 3/243 7436
T: 0 ( 7207) P:99 I:200 C: 511845 Min: 15 Act: 30 Avg: 27 Max: 909
T: 1 ( 7208) P:99 I:200 C: 511534 Min: 15 Act: 39 Avg: 31 Max: 462
I get too high jitter.
I am wondering if tuning a bit the kernel could help:
skew_tick=1
idle=poll
...
But OpenStLinux has no grub bootloader.
