A confusing problem about jetson tx2, ros_camera, HDMI screen, jtop command

Hi, I am using jetson TX2 to transport image from three usb camera via ROS. I installed ros package uvc_camera. My jetson is on a robot, and I want to control it by SSH.
I rewrote the roslaunch file to create three nodes and different image topics, then I tested it with a HDMI screen connected ,nothing went wrong, I can see three cameras’ image on master computer. But the second I unplugged HDMI, jetson’s teminal logged error"select timeout in grab", and all topics showed no new message.
After many times of searching and trial, I find without HDMI screen, if I run jtop (which monitors jetson’s states) first, and then run roslaunch, it works too. I also find after jtop command, the network latency between jetson and ros master computer changes from 280ms to 20ms! But this change doesn’t happen with plugging and unplugging of screen.
Above is the problem I met and what I found confusing. I guess the plugging of HDMI screen and jtop command may activate some kind of clock mode or some powerful working mode? Thank you for your opinion.

Hao

@WayneWWW
Could you help to check this topic if can give advice?

Thanks

Hi,

Did you see any clk being pull up if you run tegrastats with HDMI connected?