ubilinux and PREEMPT_RT kernel support

machinekodermachinekoder Posts: 14New Member

It would be great if ubilinux would support a PREEMPT_RT patched kernel. Upstream Debian comes with an RT kernel, so it wouldn't be hard to compile one for ubilinux as well.

I'm also willing to do this myself. Can you please confirm that these instructions work for ubilinux: https://wiki.up-community.org/Compile_ubilinux_kernel_from_source

Also, which kernel patch version is the current is the kernel on branch upboard-4.9? So I can select the correct RT patch.

Comments

  • Jesse KaukonenJesse Kaukonen Posts: 41New Member ✭✭

    The kernel is 4.9.65, and I've used those instructions without issues.

  • ccaldeccalde Posts: 199New Member, Emutex mod

    Hi @machinekoder ,

    The instructions are working properly for Ubilinux kernel.

    Cheers!

  • machinekodermachinekoder Posts: 14New Member

    Thanks, the instructions work great to build a kernel for upstream Debian:

    uname -a
    Linux upsquared 4.9.45-rt57-upboard-rt+ #1 SMP PREEMPT RT Thu Aug 9 12:02:41 CEST 2018 x86_64 GNU/Linux

    Applying the RT patches worked perfectly, I only had to manually modify one file afterward.

    @Jesse Kaukonen The pach level seems to be 4.9.45 in my case.

  • DCleriDCleri Posts: 548Administrator, AAEON admin

    Great machinekoder!

    Can you share a link to the source code/configuration on github so we could add to the wiki?

  • machinekodermachinekoder Posts: 14New Member

    I've created a description on my blog: https://machinekoder.com/compiling-an-rt-kernel-for-the-up-suared/

    However, the RT performance I get out of the Up^2 isn't really good so far. cyclic test gets me a latency of about 150us, even after tuning various kernel parameters. We have seen similar behavior with some wifi cards on other systems. I don't have a wifi card in my setup, but there might some other hardware causing problems. Does anyone know if there is another peripheral that could cause problems with RT latency on the Up^2?

  • eduncan911eduncan911 Posts: 157Administrator, Moderator admin
    edited October 7

    @machinekoder said:
    I've created a description on my blog: https://machinekoder.com/compiling-an-rt-kernel-for-the-up-suared/

    However, the RT performance I get out of the Up^2 isn't really good so far. cyclic test gets me a latency of about 150us, even after tuning various kernel parameters. We have seen similar behavior with some wifi cards on other systems. I don't have a wifi card in my setup, but there might some other hardware causing problems. Does anyone know if there is another peripheral that could cause problems with RT latency on the Up^2?

    Taking a look at the UP^2 block diagram:

    I would start to disable a number if components to see what might be causing the blocking calls, though there isn't much.

    Maybe try disabling the Realtek NICs over PCIe; but, does PCIe cause blocking in kernel threads?

    The GPIO header uses several paths for the FPGA. However, I am not sure it can be completely disabled with the GPIO settings in the bios.

    Besides those, there is not much left that are not native to the chipset.

    Eric Duncan - UP Evangelist - My thoughts are of my own free will

    Answered? Please remember to mark the posted answered to highlight it for future visitors!

Sign In or Register to comment.