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A.M.
Associate III
March 13, 2023
Question

How to run OpenStLinux with boot arguments like skew_tick? On STM32MP15.

  • March 13, 2023
  • 0 replies
  • 965 views

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.

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