Isolcpus and Denver cores

I’ve just stumbled across similar issues to those outlined in this forum thread: Cannot enable denver cores for TX2 (Jetpack 4.4 DP)

I was able to get my TX2 NX to schedule processes on all 6 cores by replacing isolcpus=1-2 with isolcpus= in /boot/extlinux/extlinux.conf, which is good.

That being said, I have some questions resulting from reading that ^ thread.

  1. Is that change in /boot/extlinux/extlinux.conf going to be “undone” every time I run apt upgrade as mentioned in the thread? We are on L4T 32.6.1, has this behavior been patched?
  2. The release notes explaining the reason why the Denver cores are disabled by default are a little vague. What kind of workloads are negatively impacted by running on the denver cores? NN inference for example?

Thanks for the help!


No. By default we disable Denver cores. For enabling the cores, have to execute the steps:
Cannot enable denver cores for TX2 (Jetpack 4.4 DP) - #48 by WayneWWW

Yes, for heavy GPU loading with multi CUDA kernels. You may try to enable the cores and see if GPU engine provides target performance. If you don’t load GPU to 100% during most of time in your use-case, it should be fine to enable the cores.

@DaneLLL I have already successfully enabled the cores. My first question is about whether the change I made in ‘/boot/extlinux/extlinux.conf’ will be permanent and persist even if I apply OTA upgrades using ‘apt upgrade’. Comments in the thread I linked mention the Denver cores going back to being disabled after ‘apt upgrade’.

Our use case is fairly GPU heavy. We are using TensorRT to run NN inference on images at 30 fps. I’m not sure we’re loading the GPU to 100% at all times currently, but we aren’t far from it. Are you saying that by simply enabling the Denver cores the GPU performance may suffer? Or will GPU performance only be affected if a process using CUDA is scheduled on one of the Denver cores?

Since by default the cores are disabled. After apt upgrade, you would need to execute the steps manually again.

And the performance degrade is due to task switch between A57 and Denver cores. Better performance is to keep CPU hotplug mechanism to only A57 cores. And manually schedule tasks to the Denver cores. We run glmark2 in profiling the performance.

For checking GPU loading please run sudo tegrastats

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