Last edited 8 months ago

How to monitor the GCNANO GPU load

Applicable for STM32MP15x lines, STM32MP25x lines

1. Basic usage[edit source]

When a GPU-based animation is running on the display, the related GCNANO estimated GPU load can be monitored from the GCNANO driver level, by using the following command:

 (while true; do 
gpu1=$(cat /sys/kernel/debug/gc/idle); \
sleep 4; \
gpu2=$(cat /sys/kernel/debug/gc/idle); \
echo $gpu1 $gpu2 | tr -d '\n' | tr -d ',' | tr -d 'ns' | awk -F" " '{printf("gpu load %.0f%%\n", ($10-$2)*100/($10+$12+$14+$16-$2-$4-$6-$8))}'; \
done) &

The GCNANO estimated GPU load is then periodically output in the user console as a percentage "%":

gpu load 75%
gpu load 75%
gpu load 75%

2. Tips[edit source]

  • Stop monitoring the GPU load with the command "kill -9 `ps -o ppid= -C sleep`". This command may not work depending on your system configuration (busybox ps features, sh shell configuration...). Alternative method is to use the command "fg" followed by "CTRL+C" in your terminal.
  • Debugfs[1] configuration needs to be enabled in order to be able to monitor the GPU load from the debug directory "/sys/kernel/debug/gc".
  • Adjust the GPU load update period by modifying the "sleep" value (4 seconds in the above examples).
  • Use the dmesg[2] command "dmesg -n8" to mix both user and kernel console outputs.
  • The detailed calculation is: GPU load = (On-previous_On) / (Total-previous_Total) with Total=On+Off+Idle+Suspend, all variables coming from the command:
 cat /sys/kernel/debug/gc/idle
On:                2,071,009,284,477 ns
Off:              11,480,071,864,263 ns
Idle:                              0 ns
Suspend:           1,242,043,838,898 ns

3. References[edit source]