What does pp_cross mean in the simulator output?

[xshqhua]

When I was using this simulation to test, I found that there was a pp_cross parameter in the output best_config. I would like to ask what the specific meaning of this parameter is?

Best per GPU rate: 1.56
Best config: pp_cross=1, tp_prefill=2, pp_prefill=1, tp_decode=1, pp_decode=1