V4L2 camera limitations on Verdin iMX8MP

[ToradexAI]

Hi, I’m the Toradex AI Assistant. The Toradex Support team will follow up with you shortly!

Did you like my answer?

---

Hello Aljoscha,

Thank you for reaching out to the community with your question. It sounds like you’re encountering a performance bottleneck when using the v4l2 driver in your C++ application compared to command line tools like v4l2-ctl or GStreamer. Let’s explore some potential areas to investigate:

1. Memory Mapping and Access:

   • Since you’re using mmap, ensure that the memory is correctly aligned and that your access patterns are optimized for the CPU cache. The high CPU usage suggests that the memory copying process might be inefficient. Consider exploring alternatives to std::memcpy() that could better utilize the CPU’s capabilities.

2. CPU and Cache Optimization:

   • You’ve already tried manual cache invalidation and prefetching, which is great. Double-check that these operations are correctly implemented, as incorrect cache handling can degrade performance. Additionally, while you’ve used -march=archv8-a+simd and -mtune=cortex-a53, experimenting with different compiler flags or combinations might yield better results.

3. Driver and Kernel Considerations:

   • Verify that the v4l2 driver and kernel are optimally configured for your use case. Sometimes, driver settings or kernel parameters can impact performance. Ensure you have the latest updates or patches for the driver that might address performance issues.

4. Benchmarking and Profiling:

   • Use profiling tools to identify where the bottlenecks occur in your application. This can provide insights into whether the issue is with memory copying, CPU usage, or another part of the process.

Given the complexity of the issue, a combination of these approaches might be necessary to achieve the desired performance. If the problem persists, further investigation into the specific interactions between your application and the v4l2 driver may be required.

I hope these suggestions help you improve the performance of your application.

Best regards,
Toradex AI Assistant

Please, also check if these links can help you solve your problem:

USB Camera inconsistent framerate

I have bought a usb camera with uvc drivers so it is plug and play on the mallow carrier board which we are using. I am noticing though when i run the camera, i get large scale fluctuations on my loop timings. The camera seems to jog between 25fps to 17fps. The loop is doing a bunch of other things, but when i run the script on a csi camera, i get a consistent 22 fps output. This is all done in python using opencv. Any ideas on what could be causing this? tdx-info output Software summary Boot…

https://www.nxp.com/docs/en/user-guide/IMX-MACHINE-LEARNING-UG.pdf.