Mesa hm2/hm2_7i96s.0: error finishing read

That large of a latency spike is likely power management related

Are you sure all CPU frequency switching is disabled in the BIOS?

Yep double and tripple checked. Running normally the read.time is between 370k and 520k when it blips it goes to around 1.6M

I just booted up my other box deb10 cnc 2.8 and 4.19.0-17-rt-amd64 and its rock solid at about 500k ish. it is different hardware though so not really a fair test tomorrow i will try the exact hardware

bensttech wrote:

model name      : Intel(R) Celeron(R) CPU  J1900  @ 1.99GHz

FWIW if you search the forum for J1900 you'll see people have mixed results with that processor. Some people swear by them, and others (myself included) couldn't get it to work reliably. Not saying that is your issue, but figured it was worth mentioning nonetheless.

Thanks for the insight the strange thing is i have another machine same mainboard same FPGA card on 2.8 and its dead stable. i suspect its kernel driver related but it v frustrating

1.6M is close to 1 ms, you might try increasing the servo thread period to 1.5 or 2 ms

That would be a work around but i would like to get to the bottom of it as i know i have another machine running same mb and fpga card without issues on 2.8.