How to monitor the display framerate

When an animation is running on the display, the related framerate can be monitored from the display driver level thanks to the command:

Board $> (while true; do export fps=`cat /sys/kernel/debug/dri/0/state | grep fps -m1 | grep -o '[0-9]\+'`; echo display ${fps}fps; sleep 4; done) &

The display framerate is then periodically output in the user console in "fps" (frames per second):

display 50fps
display 50fps
display 50fps

Notes:

Stop monitoring the framerate with the command "kill -9 `ps -o ppid= -C sleep`".
Adjust the framerate update period by modifying the "sleep" value (4 seconds in the example).
Use the command "dmesg -n8" to mix both user and kernel console outputs.
调试文件系统(debugfs) configuration needs to be enabled.

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