Open orgua opened 1 year ago
latest tests show that asking for kernel-time already takes ~ 300ns on BB Black - which explains the amplitude of the oscillation. Nevertheless this can be optimized with the proper tuning-variables.
the new BB AI 64 only takes 30 ns to get the timestamp.
Update: using a realtime-kernel (-rt) allows for improved timing, important kernel sync routines can also switch to HRTIMER_MODE_ABS_HARD
, while _HARD
is not available on normal 4.19.94-ti-r74
. Downside: higher overall load for normal processed (also shepherd-sheep)
The SPI - Chip select (CS) delay between two nodes is oscillating with ~ 0.2 Hz -> see this picture
PTP shows stable sync so the problem must be after that.
Current progress is documented here