Mesa hm2/hm2_7i96s.0: error finishing read

My test machine exhibits the latency issue on 5.18 kernels and not on 6.0 kernels
so something significant has changed (I have not tried 5.19 yet)

(plus I have tried most of the 5.x range)

I did a bit of basic research and there are a number of tuning parameters for the TCP stack so I wondered if ethernet on Bookworm et all could be improved by chaning some flags. I think a lot can be changed just by editing some text files.

Unfortunately most are written around inproving preformance in a server room.

This article talks about the challenges of usint the TCP stack with real time comms (and preempt_rt
ntrs.nasa.gov/api/citations/20200002393/...oads/20200002393.pdf

This one is interesting too and discusses some of the available flags and how to set them.
cromwell-intl.com/open-source/performance-tuning/tcp.html

Maybe somebody who knows a bit more thanI could explore. I guess a good start would be to compare Debian 10 TCP flags with Debian 12 ones.

 

The Mesa cards use UDP though (according to e.g. the 7i92 manual), so I'm not sure TCP settings are relevant? Maybe there are settings that affect both protocols.

arvidb wrote:

The Mesa cards use UDP though (according to e.g. the 7i92 manual), so I'm not sure TCP settings are relevant? Maybe there are settings that affect both protocols.

That may have been a poor choice of words. Should be networking stack, the nasa document above refers to UDP as well as TCP.

So in an attempt to recover from updating my Realtek drivers and losing the PCIe network card I tried to install Debian 11.4 and the screen went garbled...

Currently I'm not working on mesact until I get my dev PC back up and working so I can test configuration files on the 7i96S.

Burning Debian 11.5 to a SD card now with DD so I'll see in a while if I can install that and get back the PCIe network card.

JT

The 5.19.0-1-rt-amd64 kernal does not fix the error finishing read issue.

JT

JT wrote:

The 5.19.0-1-rt-amd64 kernal does not fix the error finishing read issue.

JT

Thats kinda what PCW said. He found you need to go to the 6.0 kernel but it needs to be compiled. If you look over on kernel.org it is right on the bleeding edge (19 September). I did see it will become the 5.20 kernel somewhere but not sure about that. I'm not 100% sure how  kernel releases are managed.... 

mirrors.edge.kernel.org/pub/linux/kernel/projects/rt/

Have you tried these (Intel only) kernel settings?

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash intel_idle.max_cstate=1 processor.max_cstate=1 idle=poll i915.enable_dc=0"

These seem to have helped on my Elite 800G1

PCW wrote:

My test machine exhibits the latency issue on 5.18 kernels and not on 6.0 kernels
so something significant has changed (I have not tried 5.19 yet)

(plus I have tried most of the 5.x range)

Not sure if this will work but the 6.0 preempt_rt kernel is now in debian experimental. I have not tested but this but:
add the following to /etc/apt/sources.list then:
reboot, hold breath and see if the network latency is resolved....
experimental only has the kernel packages in it
ref: packages.debian.org/experimental/kernel/  

you might also need the linux-headers. After installing the image

oops I forgot
sudo apt update
after edding sources.list