CPU Usage using stella_vslam system

[albertarla]

Hi all,

I'm working in a project using stella_vslam with ros2. For that project I have a node that is publishing a camera_image topic, then I have a Component Manager that executes multiple components running stella_vslam (in multiple threads). The feed_image of stella_vslam is called inside the image callback.

If running 3 or 4 components the cpus usage is around the 60% of average and I'm receiving the images at 30fps as expected. After this point, if I start increasing the number of component being executed the fps received starts dropping. The thing is that the CPU is not at it's limit.

Actual behaviour

As an example the results I'm getting are the following:

• 1 Component being run -> 30fps -> CPU 55%
• 2 Components being run -> 30fps -> CPU 55.5%
• ...
• 6 Components being run -> 20fps -> CPU 60%
• ...
• 8 Components being run -> 15fps -> CPU 70%
• ...
• 15 Components being run -> 4fps -> CPU 80%

Expected behaviour

I would expect that before decreasing the fps received in the components the CPU usage would increase, As an example the results I would expect are the following:

• 1 Component being run -> 30fps -> CPU 55%
• 2 Components being run -> 30fps -> CPU 55.5%
• ...
• 6 Components being run -> 30fps -> CPU 75%
• ...
• 8 Components being run -> 30fps -> CPU 90%
• ...
• 15 Components being run -> 10fps -> CPU 95%

Question

So, the question is if there is something in stella_vslam that limits the use of the CPU or something similar?