DDP, find_unused_parameters and manual optimisation

[DinoMan]

I am running my model on multiple GPUs and because it is a GAN I use manual optimisation. I initially got a warning to set find_unused_parameters to False since no unused params were found. I did this but then got another warning saying that manual optimisation does not support this. Can someone please explain why this happens. What the hit of setting find_unused_parameters to True is and if there is a solution (or workaround) so that I can set find_unused_parameters to False and continue to use manual optimisation.