Use RT-kernel on Jetson Thor DevKit

[kepts]

Hello,
Currently, I am testing RT-kernel using Jetson Thor Devkit, and the system version is R38.2.1. Recompile and burn the system after enabling rt-kernel based on the official instruction manual.KernelCustomization.html
Load the CPU throughstress and test it through cyclictest.

sudo cyclictest -t14 -p95 -a0-13 -m -i200 -D1800 -q -h1000 --policy fifo

The same method and the same instructions, but when looking at the data, it seems that the latency is higher when rt-kernel is applied. I don’t know if there’s something wrong, but I can see that the kernel is indeed rt-kernel.

Looking forward to your reply. Thank you.

[DaneLLL]

Hi,
For information, so you set up like this:
Jetson orin AGX PREEMPT-RT RT-test - #3 by DaneLLL

And non-RT kernel is worse than RT kernel?

[kepts]

Hello！

The following is non-RT kernel:

The following is RT kernel:

It seems that RT-kernel is not very stable after being enabled.

@DaneLLL

And non-RT kernel is worse than RT kernel?

For chart, RT kernel is worse than non-RT kernel.

[kangqi236]

Hi,

I also encountered the same problem. After applying the RT patch, the /proc/version does not have the PREEMPT_RT flag, and the kernel configuration options about PREEMPT are as follows:

CONFIG_PREEMPT_NONE_BUILD=y
CONFIG_PREEMPT_NONE=y

CONFIG_PREEMPT_VOLUNTARY is not set

CONFIG_PREEMPT is not set

CONFIG_PREEMPT_DYNAMIC is not set

CONFIG_HAVE_PREEMPT_DYNAMIC=y
CONFIG_HAVE_PREEMPT_DYNAMIC_KEY=y

CONFIG_PREEMPTIRQ_DELAY_TEST is not set

[kepts]

Hello,
Is there any progress on this issue now?

[kepts]

Hello，
I applied the RT-kernel patch via OTA and then tested it. I found that the effect was obvious and much better than that of the non-RT kernel.

However, when checking the l4t-rt package, it was found that only the R38.2.0 version was available. Could it be that there are still issues with the RT-kernel in R38.2.1?

And I do indeed need to apply the RT-kernel patch through the kernel, rather than via OTA!
Please take a look at this question as soon as possible and give a reply.

Thank you!

[DaneLLL]

Hi,
The issue is known and we are checking it. Will have further improvement in next Jetpack 7 release.

[kepts]

OK! Thank you very much!
Looking forward to the release and verification of the next version!

[DaneLLL]

Hi,
Please refer to the steps to enable RT kernel on AGX Thor developer kit:

Installing Real-Time Kernel — NVIDIA Jetson Linux Developer Guide

You may also try the manual steps:
Jetson AGX Thor FAQ

[kepts]

Hello,
Currently, following the guide step by step to enable the Real-Time kernel under JetPack 7.1, but the result remains the same as before. The Real-Time kernel updated via OTA performs as expected in actual tests, as shown in the figure below.

However, the Real-Time kernel compiled from source does not perform as desired.

Could you please help identify what the issue might be?

[DaneLLL]

Hi,
Please ensure you follow the steps:
R38.4.0 实时内核在接显示器之后 上下电会卡住 - #6 by DaneLLL

And confirm nvidia.ko is built with preempt_rt enabled.

[kepts]

Great! Just modified the generic_rt_build.shscript as suggested in the post, recompiled, flashed, and tested again — and it’s working now! I’ll continue further verification, but thank you so much!