Implementing iterative precopy migration podman containers, unable to capture only the dirty memory.

[rohanpadhye-cmd]

I am using the following commands:

sudo podman container checkpoint -R -e="/home/rohan/Desktop/Precopy migration/checkpoints/cp1.tar.gz" source2
sleep 1
sudo podman container checkpoint -R --pre-checkpoint -e="/home/rohan/Desktop/Precopy migration/checkpoints/predump1.tar.gz" source2
sleep 1
sudo podman container checkpoint -R -P -e="/home/rohan/Desktop/Precopy migration/checkpoints/predump2.tar.gz" source2
sleep 1
sudo podman container checkpoint -R -P -e="/home/rohan/Desktop/Precopy migration/checkpoints/predump3.tar.gz" source2
sleep 1
sudo podman container checkpoint --with-previous -R -e "/home/rohan/Desktop/Precopy migration/checkpoints/wpev3.tar.gz" source2
sleep 1

However, all the checkpoints are the same size (73.9 MB). I need the new checkpoints to capture only the dirty memory or changes since the last checkpoint or predump. What am I doing wrong?